JP3277589B2 - Projection exposure apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus used for forming a fine pattern such as a semiconductor integrated circuit and a liquid crystal device.

[0002]

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

[0003] An optical integrator (fly-eye integrator, lot-type integrator, optical fiber, or the like) is used in an illumination optical system for illuminating the reticle. Almost uniform. A fly-eye integrator (fly-eye lens) is a lens group in which several tens of single lens elements having the same shape are arranged in a plane perpendicular to the optical axis of the illumination optical system. When uniformizing the intensity distribution using a fly-eye lens, the reticle side focal plane (exit plane side)
And the reticle surface (pattern surface) are substantially connected by a Fourier transform relationship, and the reticle-side focal plane and the light source-side focal surface (incident surface side) are also connected by a Fourier transform relationship. Therefore, the pattern surface of the reticle and the light-source-side focal plane of the fly-eye lens (more precisely, the light-source-side focal plane of each lens element of the fly-eye lens) are connected in an imaging relationship (conjugate relationship). For this reason, on the reticle, the illumination light from each lens element (secondary light source image) of the fly-eye lens is added (superimposed) by passing through a condenser lens or the like, and is averaged, thereby averaging the illuminance on the reticle. It is possible to improve the property.

The reticle-side focal plane (emission plane) of the fly-eye lens is an optical Fourier transform plane with respect to the reticle pattern plane, and each position of the lens element within this emission plane is a reticle. Corresponds to the incident angle of the illumination light flux from each element to the pattern surface (accurately, its sine). Therefore, by providing an aperture stop near the exit surface, it is possible to limit the incident angle range of the illumination light beam with respect to the reticle pattern. In the conventional apparatus, the shape of the aperture stop (σ stop) is a circular transmitting portion centered on the optical axis. The ratio between the range of the angle of incidence of the illumination light beam on the reticle pattern determined by the radius of the circular aperture and the numerical aperture on the reticle side of the projection optical system is generally called a coherence factor (σ value).

[0005] Recently, in order to improve the resolution and the depth of focus, the annular illumination method and the modified light source method have attracted attention. The annular illumination method is described in, for example, Japanese Patent Application Laid-Open No. 61-9166.
As disclosed in Japanese Patent Application Laid-Open No. 2 (1993) -176, an optical Fourier transform surface for a reticle pattern in an illumination optical system (for example, an exit surface of a fly-eye lens) or a stop having a ring-shaped light transmitting portion in the vicinity thereof ( A ring stop) is arranged to block the illumination light flux near the optical axis of the illumination optical system. The deformed light source method is, for example, a diaphragm having a Fourier transform surface or at least one light transmitting portion eccentric from the optical axis of the illumination optical system in the vicinity thereof, as disclosed in the Fall Meeting of the Japan Society of Applied Physics, 1991. (Deformation light source aperture) is arranged to irradiate the reticle pattern with the illumination light beam inclined.

[0006]

A conventional annular stop includes a circular light-shielding portion having a radius r ₂ (<r ₁ ) in a circular transmission portion having a radius r ₁ centered on the optical axis of the illumination optical system. Is merely provided. Further, the deformed light source stop is merely a cross-shaped light-shielding portion formed on a glass substrate. On the other hand, a fly-eye lens is formed by arranging a plurality of lenses each having a square or rectangular shape. In general, a projection exposure apparatus employs so-called Koehler illumination, which forms an image of a light source such as a mercury lamp on the exit surface of a fly-eye lens (optical Fourier transform surface of a reticle pattern). Therefore, what acts as a secondary light source on the exit surface of the fly-eye lens is a discrete light source image formed only at the center of each element, and the entire exit surface does not emit light uniformly. Absent.

When the annular secondary stop as described above is provided in such a discrete secondary light source, some of a plurality of secondary light source images (corresponding to each lens element) are transmitted through the aperture of the stop and blocked. It overlaps the boundary with the part. This means that the secondary light source image near the boundary is shielded by the aperture or conversely transmitted depending on the mounting (setting) accuracy of the aperture to the fly-eye lens. That is, it may be an unstable factor such as variation in the amount of illumination light. In particular, when the annular stop is provided, there is a problem that the number of effective lens elements (secondary light sources that can pass through the annular stop) is reduced, and the effect of equalizing the illuminance on the reticle is reduced.

Further, in the projection exposure apparatus, not only the annular illumination method but also a conventional illumination method depending on the reticle pattern (fineness, periodicity, etc.), that is, a method of setting a circular transmitting portion on the exit surface of the fly-eye lens ( In the following, this is also called a normal illumination method). Therefore, when switching between the annular illumination method and the normal illumination method is used, at least two types of apertures need to be interchangeably disposed with respect to the exit surface of the fly-eye lens. And durability) must be extremely strict.

The shape of the illumination range (illumination field) on the reticle by the illumination light beam is generally rectangular so as to match the shape of the semiconductor chip to be formed on the wafer. Therefore, the shape of each element of the fly-eye lens is often rectangular (rectangular). When the annular stop as described above is applied to a fly-eye lens in which a plurality of rectangular elements are arranged, the axial direction on the short side (short direction) and the axial direction on the long side of each element of the fly-eye lens (short direction) The number of effective (not shielded by the aperture) secondary light sources (light source images) differs in the longitudinal direction). As a result, the line width (light amount distribution) of the transferred image differs between the vertical direction and the horizontal direction (corresponding to the longitudinal direction and the lateral direction of the element) of the reticle pattern to be exposed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the mounting (setting) accuracy in the illumination optical system may be low, and a line width difference occurs between the vertical and horizontal directions of the transferred image. It is an object of the present invention to provide a higher-performance projection exposure apparatus having no aperture.

[0011]

According to the present invention, a plurality of light source images are formed on a Fourier transform plane with respect to a pattern plane of a mask (R) in an illumination optical system or on a plane in the vicinity thereof. A fly-eye integrator (7) for limiting illumination light passing through the Fourier transform surface to an annular zone centered on the optical axis (AX) of the illumination optical system, and a first pattern (14a) in the annular zone An aperture member (30) for partially shielding or dimming a plurality of light source images is provided so that the number of light source images contributing to the resolution of the second pattern (14b) is equal to the number of light source images contributing to the resolution of the second pattern (14b). I did it. Further, the shape of the light transmitting portion (or the light blocking portion) of the aperture member is determined according to the arrangement of a plurality of optical elements constituting the fly-eye integrator.

[0012]

According to the present invention, the first extending members extending in directions orthogonal to each other are provided.
Since the number of light source images contributing to the resolution of each of the pattern and the second pattern is the same, the line width (light amount distribution) of the transferred image between the first pattern and the second pattern can be substantially matched. Focusing on the fact that what acts as a secondary light source within the focal plane on the exit side of the fly-eye integrator is a discrete light source image formed at the center of each optical element, The shape of the stop member (σ stop, annular stop, deformed light source stop) arranged in the vicinity is determined by the arrangement of a plurality of optical elements constituting the fly-eye lens, that is, the discrete shape formed on the exit surface of the fly-eye lens. It is determined according to the arrangement of the appropriate light source images (secondary light sources formed on the exit surfaces of the elements). For this reason, it is possible to determine the shape of the stop member so that each light source image does not overlap near the boundary between the light shielding portion and the light transmitting portion of the light shielding member.

[0013]

FIG. 1 shows a schematic configuration of a projection exposure apparatus according to an embodiment of the present invention. An illumination light beam 3 emitted from a light source 1 such as a mercury lamp is reflected and focused by an elliptical mirror 2, and a bending mirror 5 is provided. Through the input lens systems 4 and 6 to become a substantially parallel light beam and enter the fly-eye lens 7. here,
The respective incident side surfaces of the plurality of lens elements 7a constituting the fly-eye lens 7 are substantially conjugate (image-forming relationship) with the pattern surface of the reticle R. Further, an image (secondary light source) of the light source 1 is formed on the emission side surface of each lens element 7a, and the emission side surface of the fly-eye lens 7 is optically related to the pattern surface of the reticle R by the Fourier transform. Has become. In this embodiment, the aperture member 8 is provided near the exit surface of the fly-eye lens 7. The specific shape of the aperture member 8 will be described later. In addition, the fly-eye lens 7 has an optical axis A from the exit surface of each lens element 7a.
An image of the light source 1 may be formed in a plane separated by a predetermined distance in the X direction. By the way, the diaphragm member 8 is a holding member (eg, turret plate, slider, etc.) 1 together with the diaphragm member 9.
0, and is disposed in the illumination optical path so as to be exchangeable by the drive system 10a. Further, the number (type) of apertures to be fixed to the holding member 10 may be arbitrary, and the plurality of apertures are arranged, for example, in a turret shape.

The light beam 13 transmitted through the stop 8 (light transmitting portions 8a and 8b) illuminates the pattern 14 of the reticle R via the condenser lens group 11 and the mirror 12. The light transmitted and diffracted through the pattern 14 is projected onto the projection optical system 15.
To form an image of the pattern 14 on the wafer 16. The wafer 16 is placed on a stage 17 that can be moved two-dimensionally by a motor 18.

In FIG. 1, the reticle pattern 14 and the exit surface of the fly-eye lens 7 are optically Fourier-transformed, that is, the diaphragm 8 is substantially Fourier-transformed with the reticle pattern 14. Therefore, each position of the light transmitting portions 8a and 8b in the plane of the stop 8 is
This corresponds to the angle of incidence θ of the illumination light beam 13 on the reticle pattern 14.

The main control system 20 determines the most suitable (optimal) diaphragm for the reticle pattern 14 based on the type of the reticle, the fineness (line width, pitch), periodicity, etc. of the reticle pattern, by using the drive system 10a. Placed in the illumination light path through (setting)
In addition, it controls the whole apparatus. Although not shown,
The main control system 20 reads a barcode pattern on the reticle R by a barcode reader, and sets an optimum aperture based on the information. It should be noted that an optimum aperture for the reticle pattern may be written in the barcode pattern. Alternatively, the main control system 20 stores (retrieved in advance) the reticle name and the corresponding illumination condition, compares the reticle name described in the bar code pattern with the above stored contents, and determines the optimum reticle pattern. The illumination condition may be determined, and the aperture most suited to the condition may be selected (set).

Before describing the specific configuration of the aperture member suitable for the apparatus of FIG. 1, an aperture member applied to a conventional apparatus will be described with reference to FIG. FIG. 6 is a diagram of the exit side surface of the fly-eye lens 7 as viewed from the reticle side (the optical axis direction of the illumination optical system). As shown in FIG. 6, the fly-eye lens 7 has a plurality of rectangular lens elements 7a arranged in a row in the horizontal direction (X direction) and six in the vertical direction (Y direction). The lens elements are not arranged at the corners), and a total of 44 lens elements are configured. At this time, the image Li of the light source 1
(Black circles in the figure) are formed at the center of each element 7a. Further, in FIG. 6, a normal (conventional) circular diaphragm (σ diaphragm having a circular aperture) 25 is attached to the fly-eye lens 7 having the above configuration. Although not shown, the outside of the circular stop 25 is a light shielding portion.

By the way, in the area (broken line) A in FIG.
The zero lens element (light source image Li) is particularly effective for resolving a fine pattern (hereinafter, referred to as a vertical pattern) formed to extend in the Y direction on the reticle R. On the other hand, the 14 lens elements (light source images) in the area (two-dot chain line) B are effective for resolving a fine pattern (hereinafter, referred to as a horizontal pattern) formed extending on the reticle R in the X direction. It is. Further, the light source image Li in the area A is invalid (does not contribute to the resolution) in the resolution of the horizontal pattern, and the light source image Li in the area B is invalid in the resolution of the vertical pattern. . This relationship will be described with reference to FIGS.

[0019] In FIG. 7 (A), (corresponding to the region A, the light source image exactly in the area D _V is) two partial areas (hatched portion) D _V in the diaphragm 25, in FIG. 7 (B) This is effective for the fine reticle pattern (vertical direction pattern) 14a shown. Further, two partial regions (hatched portions) D in FIG.
_H (corresponding to region B) is effective for the fine reticle pattern (horizontal pattern) 14b shown in FIG. Furthermore, when including the aspect both fine reticle pattern 14c as shown in FIG. 9 (B), contained in both of the regions D _H in the region D _V and 8 in FIG. 7 (A) (A) The four partial regions (hatched portions) D _VH (the light source image inside) are particularly effective.

However, in the conventional circular diaphragm 25 shown in FIG. 6, the number of light source images (secondary light sources) Li included in the area A is ten, and the number of light source images included in the area B is ten. It will be 14 pieces. As a result, the number of light source images that contribute to the formation (resolution) of the vertical direction pattern (1 in the area A).
0, and 10 in the area opposite to the area A (left side in the drawing) with the center of the fly-eye lens 7 interposed therebetween, for a total of 20 pieces.
And the number of light source images contributing to the formation of the horizontal pattern (a total of 28, i.e., 14 in area B and 14 on the opposite side (upper side in the paper)). For this reason, for example, in the transferred image of the reticle pattern 14c shown in FIG. 9B, the image light amounts (that is, line widths) of the vertical pattern and the horizontal pattern are different.

Next, a specific configuration of the aperture member according to the embodiment of the present invention will be described with reference to FIG. FIG.
The configuration (arrangement) of the fly-eye lens 7 shown in (A) and (B) is the same as that shown in FIG. First, FIG.
In (A), a diaphragm used as a σ diaphragm (aperture stop) in the illumination optical system will be described. This stop is the same as the stop 9 shown in FIG. FIG. 2 (A)
The stop 9 shown in FIG. 6 shields only four light source images Li in the region B that contributes to the formation of the horizontal pattern, compared to the stop 25 in FIG. Further, aperture 9 (light transmitting portion 9a)
Was made to follow the shape of each element of the fly-eye lens 7. In other words, the boundary (edge) between the light-shielding portion (hatched portion) and the light transmitting portion 9a in the stop 9 is made substantially along the boundary between the elements. As a result,
The number of light source images in the peripheral portion of the light transmitting portion 9a, that is, the number of light source images in the area A (dotted line) and the number of light source images in the area (two-dot chain line) B are both 1
There are no lines, and there is no line width difference between the vertical pattern and the horizontal pattern.

In FIG. 2A, the light source images contributing to the formation of the horizontal pattern are not only those in the area B but also an area B symmetrical with respect to the center of the fly-eye lens 7 (upper side in the drawing). Since the light source images in the region B ′ also contribute similarly, only four light source images in the region B ′ are shielded from light, and the number thereof is set to ten. Further, it is desirable that the number of light source images to be shielded in the regions B and B ′ be the same, and that the positions thereof be symmetrical with respect to the center of the fly-eye lens 7. This is exactly the same for the region A. In FIG. 2A, the shape of the stop 9 is determined so as to be vertically symmetric and left-right symmetric in the plane of the paper. The aperture 9 may be one in which an opening is formed by hollowing out a metal plate by etching or the like, or one in which a light-shielding layer is formed of chrome or the like on a transparent substrate (a glass substrate such as quartz). As the σ stop, in addition to the stop 9 in FIG. 2A, the stops 37 and 38 as shown in FIGS. 11A and 11B.
May be used, and by integrally fixing them to the holding member 10, the σ value of the illumination optical system can be easily changed. The conditions for forming the apertures 37 and 38 are exactly the same as those for the aperture 9.

Next, the annular diaphragm will be described with reference to FIG. In FIG. 2B, the stop 30 has a rectangular light-shielding portion 30a near the center of the fly-eye lens 7 (optical axis of the illumination optical system), and a total of 16 lens elements in 4 rows and 4 rows (Light source image Li) was shielded.
Further, the light-shielding portion 30a has a shape following the boundary between the lens elements of the fly-eye lens 7. At this time, the number of light source images in the area A effective for forming the vertical pattern
The number of light source images in the area B effective for forming the horizontal pattern is 10 each (20 in total).
Accordingly, there is no line width difference between the vertical pattern and the horizontal pattern. On the other hand, in the conventional annular stop 26 as shown in FIG. 10A, the number of light source images in the area A is eight and the number of light source images in the area B is ten due to the circular light shielding portion 26a. Thus, a line width difference occurs between the vertical pattern and the horizontal pattern. By the way, the effect of improving the resolution and the depth of focus by the annular illumination method can be obtained by shielding the illumination light flux near the optical axis in the exit surface of the fly-eye lens 7 (optical Fourier transform surface of the reticle pattern). Things. Therefore, even if the stop 30 shown in FIG. 2B is used, the effect of improving the resolution and the depth of focus can be obtained in exactly the same manner as a normal annular stop.

In the conventional annular diaphragm 27 as shown in FIG. 10B, depending on the diameter (the inner diameter and the outer diameter of the annular light transmitting portion), the circular light blocking portion 27a and the light transmitting portion may be separated. The light source images of some lens elements may overlap the boundary. Therefore, depending on the mounting (setting) accuracy of the annular stop 27 with respect to the fly-eye lens 7, the illuminance on the reticle surface or the like greatly changes due to a slight shift of the annular stop 27, and it becomes difficult to control the exposure amount. Occurs. This problem also occurs in the circular diaphragm 25 shown in FIG. 6 in exactly the same manner. However, in the circular diaphragm 25, the number of lens elements (light source images) in the transmission portion is large, and is alleviated to some extent by the averaging effect. On the other hand, in the annular stop 27 in FIG. 10B, a considerable number of lens elements are hidden (shielded) by the circular light-shielding portion 27a, so that the influence of the mounting accuracy becomes more remarkable.

As described above, in the σ stop and the annular stop shown in FIGS. 2A and 2B, the shape of the light shielding portion is determined according to the shape of each lens element, and the shape of the light shielding portion and the light transmitting portion is determined. The light source image by the lens element was prevented from overlapping any part on the boundary line. Therefore, even if the accuracy of attaching the stop to the fly-eye lens 7 is poor, the illuminance on the reticle surface does not fluctuate, and the time required for exchanging a plurality of stops can be reduced. Note that the size of the light-shielding portion (or light-transmitting portion), that is, the number of light source images to be shielded, is uniquely determined according to the σ value, the orbicular zone ratio (ratio between the inner diameter and the outer diameter), and the like.

In the above embodiment, a fly-eye lens composed of rectangular lens elements having eight rows and six rows is used. However, the shape and arrangement of the fly-eye lens, the shape of each element, etc. It may be something.
FIG. 2 also shows the shape of the stop (light-shielding portion or light transmitting portion).
Any shape other than the above may be used, as long as the shape follows the arrangement and shape of each element of the fly-eye lens (boundary between elements). Further, although not shown in FIG. 1, the stop may be arranged other than near the exit surface of the fly-eye lens 7, for example, near its conjugate plane (optical Fourier transform plane of the reticle pattern). Further, it may be arranged near the incident side surface of the fly-eye lens 7.

By the way, the annular diaphragm 3 shown in FIG.
In the case of 0, an illuminating light beam near the optical axis is shielded by the light-shielding portion 30a. Therefore, a diaphragm having a light-shielding portion 30a made of chrome or the like on a substrate (glass substrate such as quartz) transparent to the illumination wavelength is used. . Alternatively, as shown in FIG. 3, an aperture 32 formed by hollowing out four light transmitting portions (openings) in a metal plate by etching or the like may be used. In the stop 32, a light shielding unit 32a for shielding the illumination light flux near the optical axis is provided.
However, here, it is connected and fixed to the aperture main body (light shielding portion 32c) by four support portions 32b. At this time, the support portion 32b is also formed according to the arrangement (shape) of the lens elements of the fly-eye lens 7 so as not to overlap with the light source image Li (do not shield light). Further, the light shielding portion 32c for defining the outer diameter of the annular opening is also a light shielding portion 3c for defining the inner diameter of the annular opening.
2a (corresponding to the light-shielding portion 30a of the diaphragm 30 in FIG. 2B)
Similarly to the above, the shape was determined according to the shape of each lens element, so that the light source image did not overlap the boundary line with the opening. Also, the number of light source images contributing to the formation of the vertical pattern and the horizontal pattern in the stop 32 is 10 (20 in total). In addition, by preparing a plurality of diaphragms having different sizes of the light shielding portions 32a and 32c from each other, and changing the number of light source images Li to be shielded by appropriately changing the diaphragms, the inner diameter, the outer diameter, and the The value corresponding to the annular ratio can be changed.

Further, in FIGS. 2B and 3, the annular illumination is realized by one stop, but as shown in FIG.
The plurality of diaphragms 33 and 34 may be arranged very close to each other, and annular illumination may be realized by overlapping the light blocking portions of the respective diaphragms. At this time, the conditions for forming the apertures 33 and 34 are exactly the same as those for the apertures 30 and 32 and the like, and the light-shielding portions are formed in accordance with the shape of each element so that the light source image does not overlap the boundary between the light-shielding portion and the light transmitting portion. Has formed. The aperture 33 is used to set the outer diameter of the annular illumination,
Numeral 4 designates the inner diameter, and both are formed following the shape of each lens element. The outer diameter stop 33 has a large opening inside, and the inner diameter stop 34 has a light blocking portion 34a for blocking the illumination light flux near the optical axis.
The apertures 33 and 34 may be arranged separately in the vicinity of the exit surface of the fly-eye lens 7 and in the vicinity of its conjugate surface. The number of apertures may be three or more. Further, by configuring the diaphragms 33 and 34 to be independently replaceable with a plurality of diaphragms, it becomes possible to easily change the inner diameter, the outer diameter, and the annular ratio of the annular illumination.

Further, as a diaphragm exchange mechanism, any system including a system in which a plurality of diaphragms are fixed to a turret plate and the turret plate is rotated to exchange the diaphragm, or a system using a slider as shown in FIG. You may adopt it. In FIG. 5, two sets of sliders 35 and 36 are arranged very close to each other, and three apertures 35A to 35C on the slider 35 are σ apertures or outer diameter apertures for annular illumination. On the other hand, the stop 36A on the slider 36 allows the light source images of all the lens elements of the fly-eye lens 7 to pass through the light transmitting portion, and the remaining two 36
Reference numerals B and 36C denote inner-diameter apertures for annular illumination. For example, when the stop 36A and each of the stops 35A to 35C are combined, the σ value of the illumination optical system can be changed, and the stop 35A and the stop 3
Combination with each of 6B and 36C, or diaphragm 35B
The combination of the aperture and the stop 36C makes it possible to easily change the inner diameter and the outer diameter (and the annular ratio) of the annular illumination. The number of apertures fixed to one slider may be any number, but the number is particularly limited to two or three. Are arranged very close to the exit surface of the fly-eye lens 7 or are separately arranged in the vicinity of the conjugate plane thereof, whereby the exchange mechanism can be made smaller than in the case where a turret plate is used. The apertures fixed to the slider may be the apertures shown in FIGS.

In the above embodiment, the present invention is applied to the orbital aperture and the σ
The case where the present invention is applied to the aperture has been described.
The same effect can be obtained by applying the present invention to a diaphragm through which the illumination light flux passes only through the four regions D _VH shown in FIG. This type of diaphragm is a diaphragm (effective for the oblique illumination method) that can be expected to have higher resolution and a larger depth of focus than the annular illumination, and an example thereof is shown in FIG.
As shown in FIG. 12, even at the stop 39, a light-shielding portion is formed in accordance with the shape and arrangement of each element so that the light source image Li does not overlap the boundary line between the light-shielding portion and the light transmitting portion. Also in the modified light source stop 39 in FIG. 12, the number of light source images that contribute to the formation of the vertical pattern and the horizontal pattern is 10 (20 in total). The aperture 40 shown in FIG. 13A is also the same as that shown in FIG. 12, but shows an example in which each light transmitting portion is formed following the shape of each element over the entire area. Note that the distance between the optical axis of the illumination optical system (the center of the fly-eye lens 7) and each center position of the four light transmitting portions (the center of gravity of the light amount distribution) is determined by the fineness (line width, pitch, etc.) of the reticle pattern. It is determined according to. Therefore, in the oblique illumination method, it is desirable to prepare a plurality of apertures (39, 40, etc.) having different distances from each other and to arrange an optimal aperture in the optical path according to the fineness of the reticle pattern. Further, the apertures 39 and 40 are particularly effective when the reticle pattern is a two-dimensional periodic pattern, and for a one-dimensional periodic pattern, the direction of the periodicity is as shown in FIG. A stop 8 having two light transmitting portions 8a and 8b corresponding to the above may be used. The stop 8 is the same as that shown in FIG.

By the way, instead of the diaphragms 39 and 40, two diaphragms as shown in FIG. 14 may be combined and used as a diaphragm. In FIG. 14, the rotating body 4
Each of 1,42, and a plurality of light shielding widths are different (in the figure two) and the light shielding blade WG _1, WG ₂ and WG _3, WG ₄ of provided together, the lens element by a combination of these light shielding blade , The number of light source images can be changed, and the position of the center of gravity of each of the four transmission regions (light amount distribution) with respect to the optical axis of the illumination optical system can be changed.
Since the light source image outside the fly-eye lens 7 cannot be shielded in the above configuration, the diaphragms (for example, the diaphragms 9, 37, and 38 shown in FIGS. It is desirable to dispose it near the exit surface of the eye lens 7. Further, each of the apertures shown in FIGS. 2B, 3 and 4 is cross-shaped (or H-shaped) around the optical axis of the illumination optical system.
), The diaphragm 3 can be used
Light shielding can be performed in exactly the same manner as in 9, 40 (or the aperture 8). Further, the σ value can be changed in the vicinity of each of the exit surfaces of the four (or two) fly-eye lenses,
A plurality of σ-stops (9, 37, 38) may be arranged so as to be exchangeable.

Incidentally, an annular diaphragm 31 as shown in FIG. 15 may be used. The diaphragm 31 shields a total of 12 lens elements (light source images Li) with a cross-shaped light-shielding portion 31a, and determines the shape of the light-shielding portion 31a according to the boundary between the lens elements of the fly-eye lens 7. However, aperture 3
In No. 1, the number of light source images contributing to the formation of the vertical pattern and the horizontal pattern is different. For this reason, a line width difference may occur between the vertical pattern and the horizontal pattern depending on the reticle pattern. However, compared to the annular diaphragm 30 of FIG. Is obtained. Further, when the number of lens elements (light source images Li) effective (not shielded by the aperture) is significantly reduced by the aperture member, the arrangement of the fly-eye lens itself is adjusted to the light transmitting portion. For example, by optimizing the arrangement of the lens elements constituting the fly-eye lens 7, that is, the even arrangement or the odd arrangement, a light source image (secondary light source image) effective for each of the vertical pattern and the horizontal pattern
Should be equal. In optimizing the arrangement of the lens elements, the evenness (even arrangement or odd arrangement) may be different between the vertical direction and the horizontal direction.

In the above description, the light blocking portions (3
0a to 32a, 34a) may be used as the light reduction unit. Further, the aperture member of the present invention may be a variable aperture using a liquid crystal display element, an electrochromic element, or the like. Further, in the apparatus of FIG. 1, only one set of fly-eye lenses is arranged, but two sets of fly-eye lenses may be arranged in series as disclosed in, for example, JP-A-63-66553. . In this case, the aperture member according to the present invention may be disposed on either the entrance side or the exit side of the first-stage (light source side) fly-eye lens or the second-stage (reticle side) fly-eye lens. When the stop member is arranged near the exit side surface of the second-stage fly-eye lens, a plurality of (corresponding to the number of lens elements of the first-stage fly-eye lens) formed on the exit surface of each lens element. 3
The next light source is light-shielded (or dimmed) in element units just like the previous embodiment. The exposure light source 1 of the projection exposure apparatus shown in FIG. 1 may use a harmonic such as an excimer laser, a metal vapor laser or a YAG laser, an X-ray, or the like, other than a mercury lamp. Although FIG. 1 shows an example in which the modified light source aperture 8 and the σ aperture 9 are exchanged, any aperture may be arranged on the holding member 10.

[0034]

As described above, according to the present invention, since a deformed diaphragm shape corresponding to the arrangement of each optical element constituting the fly-eye type integrator is employed, the mounting accuracy of the diaphragm can be reduced, and a plurality of diaphragms can be provided. In the case where the aperture is replaced and used, an effect is obtained that the accuracy of the reproduction of the mounting position accompanying the replacement may be low. Further, the present invention can also prevent a line width difference between a fine vertical line and a fine horizontal line, which has conventionally been a problem particularly in an annular diaphragm.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a configuration of a diaphragm suitable for the apparatus shown in FIG.

FIG. 3 is a diagram showing a modification of the stop shown in FIG. 2;

FIG. 4 is a view showing a modification of the stop shown in FIG. 2;

FIG. 5 is a diagram showing an example of an aperture changing mechanism in the apparatus shown in FIG.

FIG. 6 is a diagram showing a configuration of a σ stop used in a conventional apparatus.

FIG. 7 illustrates the principle of the present invention.

FIG. 8 illustrates the principle of the present invention.

FIG. 9 illustrates the principle of the present invention.

FIG. 10 is a diagram showing a configuration of an annular stop used in a conventional apparatus.

FIG. 11 is a diagram showing a modification of the σ stop suitable for the apparatus shown in FIG. 1;

FIG. 12 is a diagram showing a configuration of a stop for inclined illumination suitable for the apparatus shown in FIG. 1;

FIG. 13 is a diagram showing a configuration of a stop for inclined illumination suitable for the apparatus shown in FIG. 1;

FIG. 14 is a view showing a modification of the stop shown in FIG. 12;

FIG. 15 is a view showing a modification of the annular stop shown in FIG. 2;

[Explanation of symbols]

 7 Fly-eye lens 8, 9, 30-34, 37-40 aperture

Claims (24)

(57) [Claims] 1. A projection exposure apparatus comprising: an illumination optical system that irradiates illumination light from a light source onto a mask; and a projection optical system that forms and projects an image of a pattern of the mask on a photosensitive substrate. A plurality of light sources are formed on a Fourier transform surface or a vicinity surface thereof with respect to the pattern surface of the mask, and a plurality of optics whose end surface shapes are rectangular.
An illuminance having a fly-eye type integrator composed of elements , wherein the number of light source images contributing to the resolution of the first pattern and the number of light source images contributing to the resolution of the first pattern and the second pattern extending in directions perpendicular to each other in the pattern are the same A projection exposure apparatus comprising a uniformizing member. 2. The method according to claim 1, wherein the contribution to the resolution is based on a condition that the line widths of the transferred images of the first pattern and the second pattern are substantially equal. Projection exposure equipment. 3. A projection exposure apparatus comprising: an illumination optical system for irradiating illumination light from a light source onto a mask; and a projection optical system for forming and projecting an image of a pattern of the mask on a photosensitive substrate. A plurality of light sources are formed on a Fourier transform surface or a vicinity surface thereof with respect to the pattern surface of the mask, and a plurality of optics whose end surface shapes are rectangular.
A plurality of light source images each having a fly-eye type integrator composed of elements , wherein a first pattern and a second pattern extending in a direction orthogonal to each other in the pattern have substantially equal line widths of transferred images. A projection exposure apparatus, comprising an illuminance uniformizing member for distributing light. 4. The illuminance equalizing member can change at least one of a size and a shape of a region where the plurality of light source images are distributed according to a pattern to be transferred onto the photosensitive substrate. The projection exposure apparatus according to claim 1. 5. The illumination device according to claim 1, wherein the illuminance equalizing member distributes a plurality of light source images in an annular zone centered on an optical axis of the illumination optical system. The projection exposure apparatus according to claim 1. 6. The projection exposure apparatus according to claim 5, wherein the illuminance uniforming member can change an inner diameter, an outer diameter, or an annular ratio of the annular zone. 7. The illuminance equalizing member may include a plurality of light source images in a plurality of local regions decentered from the optical axis, the distance from the optical axis of the illumination optical system being determined according to the fineness of the pattern. The projection exposure apparatus according to any one of claims 1 to 4, wherein 8. The projection exposure apparatus according to claim 7, wherein the illuminance equalizing member can change a distance of each of the local regions with respect to an optical axis of the illumination optical system. 9. The illuminance equalizing member distributes a plurality of light source images in a predetermined area centered on the optical axis of the illumination optical system, and determines the number of the light source images in a peripheral portion in the predetermined area. The projection exposure apparatus according to claim 1, wherein the first pattern and the second pattern are substantially equal. 10. A projection exposure apparatus comprising: an illumination optical system that irradiates illumination light from a light source onto a mask; and a projection optical system that forms and projects an image of a pattern of the mask on a photosensitive substrate. A secondary light source is formed on the Fourier transform plane with respect to the pattern plane of the mask or a plane in the vicinity thereof
And a plurality of optical elements whose end faces are rectangular.
A first pattern and a second pattern extending in a direction orthogonal to each other in the pattern and having the same contribution of the secondary light source to the resolution of the first pattern and the second pattern. A projection exposure apparatus comprising a uniformizing member. 11. The first light source as a contribution of the secondary light source.
11. The projection exposure apparatus according to claim 10, wherein a line width of a transfer image between the pattern and the second pattern is substantially equal. 12. The projection exposure apparatus according to claim 10, wherein the illuminance equalizing member distributes the secondary light source in a position other than near the optical axis of the illumination optical system. 13. The illuminance equalizing member includes two strip-shaped light-shielding portions or dimming portions that are orthogonal to the optical axis of the illumination optical system and have different widths. The projection exposure apparatus according to any one of claims 8 and 12. 14. The projection exposure apparatus according to claim 13, wherein the light-shielding part or the light-reducing part is defined along a direction in which the first and second patterns extend. 15. An illumination range on the mask by the illumination optical system is rectangular, and the plurality of optical elements of the fly-eye integrator are provided.
Each is a rectangle corresponding to the illumination range
It is a projection exposure apparatus according to any one of claims 1 to 14, characterized in. 16. The projection according to claim 1, wherein the illuminance equalizing member has a stop member arranged on an entrance surface or an exit surface of the fly-eye integrator. Exposure equipment. 17. The shape of the aperture member is defined according to an arrangement of a plurality of optical elements constituting the fly-eye integrator.
7. The projection exposure apparatus according to 6. 18. A mask is illuminated via an optical integrator forming a secondary light source with illumination light from the light source,
In the projection exposure method for transferring an image of a pattern of the mask onto a photosensitive substrate, the optical integrator may have an end face having a rectangular shape.
A first pattern and a second pattern extending in a direction orthogonal to each other in the pattern, wherein the secondary light source contributes to the resolution of the first and second patterns in a similar manner. Projection exposure method. 19. The projection exposure method according to claim 18, wherein in the secondary light source, the number of light source images that contribute to the resolution of the first pattern and that of the second pattern are substantially equal. 20. The first light source as a contribution of the secondary light source.
20. The projection exposure method according to claim 18, wherein a line width of a transfer image between the pattern and the second pattern is substantially equal. 21. The secondary light source is distributed on a Fourier transform plane with respect to a pattern plane of the mask in an illumination optical system including the optical integrator or on a plane near the Fourier transform plane other than near its optical axis. 18-2
0. The projection exposure method according to any one of 0. 22. The secondary light source is characterized in that its shape is defined by two band-shaped light-shielding portions or light-reducing portions that are orthogonal to the optical axis of the illumination optical system and have different widths. A projection exposure method according to claim 21. 23. The projection exposure method according to claim 13, wherein the light shielding portion or the light reducing portion is defined along a direction in which the first and second patterns extend. 24. The illumination range on the mask by the illumination optical system is rectangular , and the plurality of optical elements of the optical integrator are provided.
Each point is a rectangle corresponding to the illumination range.
24. The projection exposure method according to claim 22 , wherein the light-shielding portion or the light-reducing portion is defined along a longitudinal direction and a lateral direction of the optical element.