JP2002057098A - Illumination optical device, aligner comprising the same, and method for fabricating microdevice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical device in which the size can be reduced while suppressing coherence of a light source, an aligner comprising the illumination optical device, and a method for fabricating a microdevice comprising the aligner. SOLUTION: Coherent light from a light source 10 is split by a half-mirror 21 and one part advances through an optical integrator system 40. The other part advances on a circulation optical path having an optical path length difference shorter than the coherence distance of the coherent light. It is then split again by the half-mirror 21 and the process is repeated. A deflection element 23 is a transparent optical element for deflecting light in a specified direction. Lights having a specified optical path length difference and a specified deflection angle and advancing through the optical integrator system 40 are mixed and passed through a light introduction system 30 before illuminating a reticle 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device used for manufacturing micro devices such as a semiconductor device, a liquid crystal display device, an imaging device, a CCD device, and a thin film magnetic head by a lithography process. The present invention relates to an exposure apparatus provided with the same, and a method for manufacturing a micro device using the exposure apparatus.

[0002]

2. Description of the Related Art In an illumination optical apparatus used for manufacturing the above-described device, a laser beam is usually used as a light source. Since laser light has good coherence, interference fringes and speckles are likely to be generated on the surface to be irradiated, and uniform illumination may not be obtained. For this reason, in the conventional apparatus, the optical path is divided and an optical path length difference greater than the coherence distance of the light source light is given to reduce the coherence of the light source light. An example is disclosed in
-198759. Also,
The light emitted from the optical path is deflected every time the optical path makes one round by using a mirror or the like, and averaging is performed to reduce speckle on the irradiated surface. An example is disclosed in JP-A-11-312631.

[0003]

The coherence length is mainly determined by the wavelength and the half-width of the wavelength, and differs depending on the type of laser and the half-width of the wavelength. For example, in the case of an excimer laser having a wavelength of 248 nm and a wavelength half width of 0.6 pm, the temporal coherence length is about 200 mm. In order to divide the optical path and provide an optical path length difference larger than such a distance, an optical system having a predetermined size or more is required. Further, if a plurality of optical paths for providing such an optical path difference are to be provided, the size of the apparatus itself is inevitably increased. From such a point, there is a first problem that providing an optical path length difference larger than the coherent distance becomes an obstacle in realizing miniaturization of the device.

Further, in order to provide a predetermined optical path difference between the optical paths divided into a plurality of optical paths, each optical member constituting an optical system for providing the optical path difference is configured with high accuracy, and The optical member needs to be set with high accuracy. However, due to these constraints, it is difficult to manufacture each optical member constituting the optical system for providing an optical path difference in a short time, and it is difficult to adjust the setting of each optical member. There is a second problem that it is difficult to assemble the optical system to be provided.

The present invention has been made in view of such a problem. A first object of the first invention is to solve the first problem and to solve the problem of light source interference. It is an object of the present invention to provide an illumination optical device capable of realizing the miniaturization of the device while reducing the performance, an exposure device provided with the illumination optical device, and a method for manufacturing a micro device using the exposure device.

A second object according to a second invention is to solve the second problem and reduce the problem of coherence, and to provide an illumination optical device which is easy to manufacture and the illumination optical device. An exposure apparatus provided with: and a method for manufacturing a micro device using the exposure apparatus.

[0007]

In order to solve the above-mentioned problems, the present invention provides a light source for supplying coherent light and a plurality of divided light sources for dividing the coherent light. An optical delay system for generating light and providing an optical path length difference shorter than the coherent distance of the coherent light between the plurality of split lights, and a light guide system for guiding light from the optical delay system to a surface to be irradiated And an illumination optical device having: By employing an optical delay system that gives an optical path length difference shorter than the coherent distance of the light source light, the size of the device can be reduced. At this time, when n is an integer equal to or greater than zero, the n-th divided light and the n-th divided light traveling on the next longest optical path after the n-th divided light are used.
It is preferable that an optical path length difference from the + 1st split light is set shorter than the coherent distance of the coherent light. Further, as described in claim 3, the optical delay system includes:
It is preferable to have a transmission type deflection element for deflecting incident light. This eliminates the need for conventional deflection mirrors and adjustment of the deflection mirrors, thereby facilitating the work. The light emitted from the split optical path is deflected by the transmission type deflection element, and speckle on the surface to be irradiated can be reduced. As the transmissive element, an element utilizing refraction or diffraction can be considered.

According to another aspect of the present invention, as described in claim 4, a light source for supplying coherent light, a plurality of divided lights generated by dividing the coherent light and a plurality of divided lights are generated. An optical delay system for providing a predetermined optical path length difference between the split light beams; and a light guide system for guiding light from the optical delay system to a surface to be illuminated, wherein the optical delay system transmits light that deflects incident light. There is provided an illumination optical device having a mold deflection element. Thereby, the adjustment of the optical delay system can be made much easier, and the device can be manufactured in a short time. In this case, it is preferable that the transmission type deflection element is an element having a different optical path length depending on a portion. As the transmission type deflection element, for example, a diffractive optical element or the like can be considered. Then, when λ is the wavelength of the coherent light as described in claim 6,
The transmission type deflection element may be configured to have a portion where the optical path length difference is larger than λ / 10, or the transmission type deflection element may have a plurality of optical path lengths different from each other. If it has a part and the size of the part is less than or equal to の of the spatial coherence of the coherent light, the wavefront of the transmitted light can be effectively displaced.

According to another aspect of the present invention, the optical delay system includes a light splitting means for splitting the coherent light to generate the plurality of split lights, and mixing the plurality of split lights. A light mixing means for guiding the light to the light guide system may be provided. At this time, as described in claim 9, the light splitting means has a light splitting surface also serving as the light mixing means, and the optical delay system re-divides the light split by the light splitting surface. A circular optical path forming unit having a plurality of deflecting surfaces for forming a circular optical path returning to the light splitting surface, wherein each of the deflecting surfaces in the circular optical path forming unit is set so as to provide the optical path length difference; It is preferred that The device configuration can be simplified by using both the light splitting means and the light mixing means. According to another aspect of the present invention, the optical delay system includes a reflecting surface and a light dividing surface disposed to face the reflecting surface, and the reflecting surface and the light dividing surface are arranged such that the reflecting surface and the light The light may be arranged so as to provide an optical path length difference shorter than the coherent distance between the split light beams from the light splitting surface toward the light guide system by performing multiple reflections with the splitting surface. By using multiple reflections, space can be saved. In this case, as described in claim 11,
The reflecting surface and the light splitting surface may be arranged non-parallel, and further, as described in claim 12, the optical delay system is provided between the reflecting surface and the light splitting surface. You may comprise so that it may further comprise the arrange | positioned deflection element.

Further, according to another aspect of the present invention, as described in claim 13, a light source for supplying coherent light, a light source for dividing the coherent light to generate a plurality of divided lights, and An optical delay system for providing a predetermined optical path length difference between the plurality of split light beams; and a light guide system for guiding light from the optical delay system to a surface to be illuminated. There is provided an illumination optical device including a reflection type deflection element capable of adjusting a deflection angle and a transmission type optical element for diffusing or diffracting light. As the transmission type optical element, for example, a phase plate having an optical path length irregularly different depending on a portion can be considered. By using such a transmission type optical element, the wavefront of the transmitted light can be changed irregularly, and even if the precision of the angle adjustment of the reflection type deflection element is loosened, the coherency of the light source light remains the same as before. Can be reduced. In this case, if the predetermined optical path length difference is configured to be shorter than the coherent distance of the coherent light, the size of the apparatus can be reduced.

According to a fifteenth aspect of the present invention, in the above light guide system, an optical integrator system for generating a secondary light source is provided for uniformly irradiating the irradiated surface. Preferably, the integrator system is configured to form 10,000 or more light source images on the secondary light source. By forming a large number of light source images, unnecessary interference fringes can be reduced. As an element constituting the optical integrator system, for example, a fly-eye lens can be considered. According to another aspect of the present invention, as described in claim 16, an illumination optical system comprising the illumination optical device according to any one of claims 1 to 15, and a mask having a predetermined pattern. An exposure apparatus, comprising: a mask holding means for setting a pattern on the irradiation surface; a projection optical system for projecting a pattern image of the mask onto a photosensitive substrate; and a substrate holding means for holding the photosensitive substrate. Is provided. Further, according to another aspect of the present invention, as in claim 17, claim 16
8. A method for manufacturing a micro device using the exposure apparatus according to claim 7, wherein a step of applying a photosensitive material on the photosensitive substrate and an image of the pattern of the mask on the photosensitive substrate via the projection optical system. And a step of developing the photosensitive material on the photosensitive substrate.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description and the accompanying drawings, components having substantially the same functions and configurations are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a configuration diagram of an exposure apparatus according to a first embodiment of the present invention. Light source (light source unit) 1
0, an optical delay system 20, a light guide system (illumination optical system) 30, and a reticle 60. The light guide system 30 includes an optical integrator system 40 and a condenser optical system 50. Here, the light source 10 as a light source unit is, for example, Kr
F excimer laser (oscillation wavelength: 248 nm), ArF excimer laser (oscillation wavelength: 193 nm), or F ₂
A laser (oscillation wavelength: 158 nm) can be used, but any light source that supplies coherent light can be used. In addition, the light beam incident on the optical path between the light source 10 and the optical delay system 20 or the optical path between the optical delay system 20 and the light guide system (illumination optical system) 30 has a desired size and sectional shape. It is also possible to arrange a beam shaping system for converting the beam into a possessed light beam, a relay system for routing an optical path, and the like.

Each of the above-described optical systems is not limited to being composed only of a refractive optical element, but may be composed of a combination of a refractive optical element and a reflective optical element, or may be composed of only a reflective optical element. It is possible.

The light source 10 is a light source that supplies coherent light. Light emitted from the light source 10 enters the optical delay system 20. The optical delay system 20 includes a half mirror 2 functioning as an amplitude division type light division member (amplitude division type partial reflection mirror).
1, a reflecting mirror 22a, 22b, 22c, 22d, and a deflecting element 23. Here, the half mirror 21 has a predetermined reflectance and a predetermined transmittance, and divides the light into transmitted light and reflected light at a predetermined ratio. The transmittance of the half mirror 21 is not limited to 50%, and the transmittance of the half mirror 21 is preferably smaller than the reflectance of the half mirror 21. Reflection mirrors 22a, 22
b, 22c and 22d are set to deflect incident light in a predetermined direction to form a circulating optical path. The optical path length d of the orbiting optical path is configured to be shorter than the temporal coherence length Lc of the light from the light source 10. The deflecting element 23 is a transmission type optical element having a function of deflecting light in a predetermined direction, as will be described later in detail.

The light from the light source first enters the optical delay system 20,
The light enters the half mirror 21 and is split into transmitted light and reflected light. The transmitted light travels to the optical integrator system 40. The reflected light enters the circulating optical path, is deflected by the deflecting element 23 in the circulating optical path, reenters the half mirror 21, and is further divided into reflected light and transmitted light. The reflected light generated by the further division is mixed along the same optical path with the light transmitted through the half mirror 21 first, and proceeds to the optical integrator system 40. The transmitted light that has been split further travels along the optical path in the optical delay system 20 again, enters the half mirror 21, is further split into reflected light and transmitted light, and the same as described above is repeated.

Light incident on the optical integrator system 40 is transmitted to the first integrator 41 and the relay optical system 4.
2. The light enters the second integrator 43 in this order. Here, the first integrator 41 and the second integrator 43 are composed of an aggregate of many lens elements, and form a secondary light source image on the emission side. Unnecessary interference fringes on the irradiated surface are reduced as the number of light source images increases. In the present embodiment, the configuration is such that 10,000 or more light source images are formed. Thereafter, the light from the light source image enters the condenser optical system 50, illuminates the reticle conjugate surface 52 with the first lens group 51, and illuminates the reticle 60, which is the irradiated surface, with the second lens group 53 almost uniformly. . Then, the predetermined pattern formed on the reticle 60 is imaged on the photosensitive substrate W (a wafer or the like) by the projection optical system PL, and the predetermined pattern image of the reticle 60 is exposed on the substrate W.

Here, reticle 60 is held on reticle stage RS, and substrate W is held on substrate stage WS. The reticle conjugate plane 52 has a reticle 60
A reticle blind (field stop) RB having a predetermined rectangular opening is set in order to define an illumination area on the upper side (or an exposure area on the substrate W). The size of the opening may be variable. Therefore, the second lens group 53 functions as an imaging optical system that forms an image of the opening of the reticle blind RB on the reticle 60.

The first integrator 41 and the second integrator 43 are members of each type, for example,
A fly-eye lens formed by an aggregate of a large number of lens elements, a micro fly-eye lens, a Fresnel lens or a diffractive optical element formed by an aggregate of a large number of microlenses, an internal reflection type rod integrator (an internal reflection type integrator) (A prism member, an internal reflection type hollow member, etc.). The first integrator 41 and the second integrator 43 may be constituted by members of the same type, or may be constituted by combining members of different types.

Particularly, in recent years, in order to improve the original resolution and depth of focus of the projection optical system PL, the shape of the secondary light source is formed into a ring shape or a multipolar shape decentered from the center, that is, a so-called ring shape. Strip lighting and multi-pole lighting are attracting attention. To cope with this, for example, the first integrator 41 may be provided with a function of converting the light into an annular light flux. Therefore, for example, the first integrator 41 includes an integrator element for normal illumination having a circular secondary light source shape, an integrator element for annular illumination having a secondary light source annular shape, and a secondary light source shape. And a multipole illumination integrator element having a multipole shape. If one of the integrator elements is inserted into the optical path, the desired illumination corresponding to the optimum reticle pattern to be exposed can be selectively performed. Can be done.

If the relay optical system 42 disposed between the two integrators is constituted by a variable power optical system, the size of the secondary light source is made variable and the coherence factor (σ
Value (the ratio of the size of the secondary light source formed on the pupil of the projection optical system to the size of the pupil of the projection optical system) may be variable.

Hereinafter, the optical delay system will be described in detail.
The half mirror 2 emits the light source and does not pass through the optical path at all.
Light passing through 1 and proceeding to the optical integrator system 40 is defined as L0. Light emitted from the light source and reflected by the half mirror 21 to make one round of the orbital optical path and then proceeding to the optical integrator system 40 is defined as L1. The light emitted from the light source and reflected by the half mirror 21 makes one round of the orbiting optical path, passes through the half mirror 21 and makes one round of the orbiting optical path, that is, light that travels to the optical integrator system 40 after making two rounds of the orbiting optical path. Is L2. Similarly, the circulating optical path has three rounds,
Zhou,. . . , N-turned light, L3, L4,. . . , Ln
And Since the optical path length of the orbiting optical path is d, L1 and L1
2, L2 and L3,. . . , Ln-1 and Ln are all d, which is shorter than the coherence length Lc of the source light.

For the sake of simplicity, consider the case where Lc / 2 <d <Lc. L1 and L2, L2 and L3,. . . Since the light path length difference between the light sets whose optical path length difference differs by one round is shorter than Lc, these light sets interfere with each other. However, L1 and L
3, L2 and L4, L3 and L5,. . . , The optical path length difference of a set of light beams whose optical path length differences differ by two rounds is 2d, and L
Since they are longer than c, these light sets do not interfere. Similarly, the optical path length difference of light whose optical path length difference differs by three or more rounds is also Lc.
Because they are longer, these light sets do not interfere. Therefore,
Interference occurs only in a set of lights whose optical path length difference differs by one round, and the other sets of light do not interfere. Interference of a set of lights having a difference in optical path length for one round can be regarded as pseudo intra-beam interference, which has occurred in the conventional apparatus, but is considered to be no problem in practical use. Have been.

Here, light effective as illumination light will be considered. Since the light is split into transmitted light and reflected light by the half mirror 21 every time the optical path makes one rotation, the light after L2 is reduced in amount by the light transmitted by the half mirror 21.
That is, L2, L3, L4,. . . , Ln in this order. Light with too little light is ineffective as illumination light. Thus, in principle, light travels along an infinite round optical path, but the light that is actually effective as illumination light is light that travels a finite number of round optical paths.

The finite number of times depends on the performance and specifications of the components of the apparatus, but it depends largely on the reflectance of the half mirror 21. By properly setting the reflectance of the half mirror 21, the types of light effective as illumination light can be increased. For example, while the light from L0 to L3 is effective in the related art, the light from L0 to L7 is made effective by setting the reflectance of the half mirror 21. As a result, the speckle pattern can be averaged using eight types of light, whereas the average of the speckle pattern is conventionally performed using four types of light.

Therefore, even when the circulating optical path length is set shorter than the coherent distance, the reflectance of the half mirror 21 is set well, and the number of types of light effective as illumination light is increased. Can be reduced. Since there is no need to make the orbiting optical path longer than the coherent distance, the size of the device can be easily reduced. Here, for the sake of simplicity, the case where Lc / 2 <d <Lc has been described, but the present invention is not limited to this, and the present invention can be applied to the case where d <Lc.

Next, the deflection element 23 will be described. Here, the deflection element 23 is a diffractive optical element having a rectangular cross section as shown in FIG. The optical paths A and B have different optical path lengths, and the optical path length difference h is configured to be larger than λ / 10. In addition, the size D of the rectangular portion is the light source 1
It is configured to be equal to or less than 1/2 of the magnitude of the spatial coherence of zero. Thus, the light incident on the deflecting element 23 is effectively displaced in the wavefront and emitted at a predetermined angle according to the law of diffraction. That is, the light incident on the deflection element 23 is deflected. Here, when the deflecting element 23 is composed of a diffractive optical element having a periodic pitch, D is half the pitch of the diffractive optical element.
Is composed of random pattern elements, D is half the average pitch of the random pattern elements.

Therefore, the light emitted from the light source is emitted from the optical delay system 20 at a predetermined angle every time the light travels around the optical path. From this, the optical integrator system 4
Since the light incident on 0 is inclined, the speckle on the irradiated surface shifts, and the contrast of the speckle pattern can be reduced. Conventionally, speckle shift is performed by deflecting light by tilting a mirror, and fine adjustment of the mirror angle is required. However, in the present embodiment, the adjustment of the light deflection angle is performed by the pitch of the diffractive optical elements of the deflection element 23. When performing alignment as an initial setting of the apparatus, the direction of travel of light is adjusted and confirmed with the deflecting element 23 removed, and then the deflecting element 23 may be set at a predetermined position. By using the element having the pitch set at the time of design and manufacture, the complicated operation of finely adjusting the mirror angle in the related art is not required, and the effect that the desired light deflection angle can be easily set can be obtained.

FIG. 3 shows a cross-sectional shape of another example of the deflection element 23. Here, the deflection element is a blaze-shaped (sawtooth-shaped) diffractive optical element 231. For this element,
Since almost 100% of the incident light becomes diffracted light, the light can be efficiently deflected. As shown in FIG. 3, the blazed diffractive optical element is not limited to one having a flat slope, but may have a curved (curved) slope.

FIG. 4 shows a sectional shape of still another example of the deflection element 23. Here, the deflecting element is constituted by a wedge-shaped prism 232, and deflects light not by diffraction but by refraction. This device has an advantage that it is much easier to manufacture than the above two devices.

FIG. 5 shows an example of an optical delay system according to the second embodiment of the present invention. In the present embodiment, only the optical delay system is different from the first embodiment, so only the optical delay system will be described below. Here, a polarization beam splitter 2 is used instead of the half mirror 21 as a means for splitting and mixing light.
4 is used. In this example, the light source 10 and the optical delay system 20
.Lambda. / 2 plate 26a is further disposed between
Lens 25a, 25b, λ / 2 plate 2
6a and 26b are further arranged. The optical path length d of the circulating optical path is configured to be shorter than the coherence length Lc of the light from the light source 10.

First, the light emitted from the light source 10 passes through the λ / 2 plate 26a. By rotating the λ / 2 plate 26a, light can be brought into a predetermined polarization state. afterwards,
The light enters the polarizing beam splitter 24, where the P-polarized light and the S-
The light is split into polarized light, and transmitted and reflected respectively. Reflected S
The polarized light goes to the optical integrator system 40. The transmitted P-polarized light travels along the circulating optical path, passes through the lens 25a, is deflected by the deflecting element 23, and passes through the lens 25b. Then, the light enters the λ / 2 plate 26b, whereby the polarization state changes. The light again enters the polarization beam splitter 24, is again divided into P-polarized light and S-polarized light, and the same is repeated. Thus, similarly to the case where the half mirror 21 is used, the division of the light and the traveling of the circulating optical path of the divided light are performed.

Here, the two lenses (25a, 25b) arranged in the orbiting optical path constitute an image-forming optical system. For example, the light splitting point almost at the center position of the deflection beam splitter 24 is set to P1. Assuming that a point substantially at the center position of the deflecting element is P2, the lens 25a (first relay optical system) forms an image of the point P1 on the point P2, and the lens 25b (second relay optical system) sets the point P2 on the point P2. An image is formed on P1. Therefore, the imaging optical systems (25a, 25b) re-image the polarization splitting surface (light splitting surface) of the polarizing beam splitter (light splitting member) 24 via the orbiting optical path. In other words, the imaging optical system (25a, 25b) includes the polarization splitting surface (light splitting surface) of the polarizing beam splitter (light splitting member) 24 and the polarizing beam splitter (light splitting member) via the orbiting optical path.
Twenty-four polarization splitting surfaces (light splitting surfaces) are optically conjugated.

At this time, it is preferable that the image forming magnification of the image forming optical system (25a, 25b) is the same.
More preferably, the imaging magnification of each of the lens 5a (first relay optical system) and the lens 25b (second relay optical system) is the same. However, the imaging magnification of the lens 25a (first relay optical system) and the lens 25b (second relay optical system) does not necessarily have to be equal, and the imaging optical systems (25a,
If the imaging magnification of 5b) becomes equal, the lens 25a (first
Relay optical system) and lens 25b (second relay optical system)
Can be set arbitrarily. For example, if the imaging magnification of the lens 25a (first relay optical system) is two times, the imaging magnification of the lens 25b (second relay optical system) is one.
/ 2 times.

The imaging optical systems (25a, 25b)
It goes without saying that the present invention is not limited to this example but can be applied to the examples shown in FIGS. 1 to 4 and the examples described below. With the above-described imaging optical systems (25a, 25b), an optical system for preventing interference fringes that does not greatly affect the performance even if an angle shift occurs can be configured. Therefore, even when a light source having a large divergence angle is used, the beam does not blur due to the divergence angle.

In the first embodiment, the half mirror 21
By setting the reflectance, the coherence of the light source was reduced.
In the present embodiment, the ratio between the reflected light and the transmitted light can be changed by rotating the λ / 2 plates 26a and 26b and the polarization beam splitter 24, and the same effect as in the first embodiment can be obtained. Can be In addition, when a half mirror is used, the reflectance of the half mirror is fixed, so that the reflectance cannot be adjusted after installation. However, in the present embodiment, the ratio between the reflected light and the transmitted light is fixed. Instead, they can be easily changed. Therefore, the present invention can be applied to trial use, and can be optimized in actual use.
For example, it is possible to flexibly cope with a change in conditions such as a change in a light source to be used, and the configuration has a high degree of freedom.

FIG. 6 shows an example of an optical delay system according to the third embodiment of the present invention. In the present embodiment, only the optical delay system is different from the first embodiment, so only the optical delay system will be described below. Here, the reflection mirror 2 of the first embodiment is used.
2b, a tilt mirror 27 and a random phase plate 28 are arranged instead of the deflection element 23. The tilt mirror 27 is a mirror that can deflect light and adjust its deflection angle. Here, the tilt mirror 27 is provided so as to be two-dimensionally tiltable as shown in FIG. 6. For example, the operator can adjust the tilt direction and tilt direction of the tilt mirror 27 via a mechanical tilting mechanism (tilting device) TS. The tilt amount can be adjusted. The random phase plate 28 is an optical element having a portion whose optical path length is irregularly different. FIG. 7 shows a cross-sectional shape of one example.

The light traveling in the optical path of the optical delay system is deflected by the tilt mirror 27 and emitted from the optical delay system. At this time, the light is diffused or diffracted by the random phase plate 28. Since the random phase plate 28 has portions having irregularly different optical path lengths, the diffusion or diffraction action is not uniform and irregular. Therefore, the coherency of the finally obtained illuminating light can be reduced as before, without making the accuracy of adjusting the deflection angle of the tilt mirror 27 strict as in the conventional case. Therefore, according to the present embodiment, an effect is obtained that the adjustment of the tilt mirror 27 for light deflection becomes easy. Although FIG. 6 shows an example in which one tilt mirror is provided, it goes without saying that a plurality of tilt mirrors may be provided.

FIG. 8 shows an example of an optical delay system according to the fourth embodiment of the present invention. In the present embodiment, only the optical delay system is different from the first embodiment, so only the optical delay system will be described below. In the present embodiment, a multi-beam optical system using multiple reflection is adopted as an optical delay system. Here, as shown in the figure, the traveling direction of light emitted from the light source 10 is defined as the z direction, the upward direction perpendicular to the plane of the drawing is defined as the y direction, and the direction perpendicular to the drawing is defined as the x direction.

The light emitted from the light source 10 enters a multi-beam optical system 29 which is an optical delay system. Multi-beam optical system 29
Are the total reflection mirror (reflection surface) 29a and the total reflection mirror 2
Partial reflection mirror (light dividing surface) 29 arranged opposite to 9a
b, and the light incident on the multi-beam optical system 29 is
As will be described in detail later, the beam is converted into a beam group including a number of parallel beams arranged in the y direction. Thereafter, the effective diameter of the beam group in the y direction is reduced by the reduction system 31.
The light enters the diffusion plate 33 via the depolarizing prism 32.
The divergent light from the diffusion plate 33 proceeds to the optical integrator system 41, and thereafter, the operation is the same as in the first embodiment. Further, an arrangement in which the optical system after the diffusion plate 33 is the same as in the first embodiment is also possible. That is, it is also possible to remove the diffusion plate 33 and the optical integrator system 41 in FIG. 8 and to arrange a micro fly's eye lens, a Fresnel lens, a diffractive optical element, and a rod-type integrator instead. However, in this arrangement, it is desirable to design so that the division unit of each of the above elements is smaller than the diameter of each beam constituting the incident multi-beam. This design is possible because each of the above elements can have a very small unit of division. Also, similarly to the first embodiment, by giving the element a function of generating annular illumination or multipolar illumination, it is possible to implement modified illumination.

Next, the multi-beam optical system 29 will be described in detail with reference to FIG. The multi-beam optical system 29 has a total reflection mirror 29a and a partial reflection mirror 29b, which are inclined by an angle θ with respect to the y direction, are substantially parallel to each other, and are arranged so that their reflection surfaces face each other. ing. The light T0 incident on the multi-beam optical system 29 along the y direction is split into transmitted light and reflected light by the partial reflection mirror 29b, the transmitted light T1 proceeds to the reduction system 31, and the reflected light travels to the total reflection mirror 29a. . Then, the light reflected by the total reflection mirror 29a goes to the partial reflection mirror 29b again, and is further divided into the transmitted light T2 and the reflected light. The transmitted light T2 travels to the reduction system 31, and the reflected light travels to the total reflection mirror 29a. The same is repeated below.
The light that has entered the multi-beam optical system 29 is multiple-reflected between the total reflection mirror 29a and the partial reflection mirror 29b, so that a plurality of beams T with a predetermined optical path length difference are provided.
, Tn. Here, since the total reflection mirror 29a and the partial reflection mirror 29b are arranged so as to be inclined with respect to the y direction, the outgoing beam is a group of many parallel beams arranged at substantially equal intervals in the y direction. Becomes In the figure, for simplicity, only a few beams are shown, and the remaining beams are omitted.
9a and the thickness of the partial reflection mirror 29b are neglected.

Here, assuming that the distance between the mirrors is d, the optical path length difference between the adjacent beams Ti and Ti-1 is about 2d.
This 2d is configured to be shorter than the temporal coherence length Lc of light. Thus, by arranging the two components of the total reflection mirror 29a and the partial reflection mirror 29b, the light from the light source 10 can be divided into a plurality of lights and a predetermined optical path length difference can be provided.

Therefore, according to the present embodiment, since a large number of beams having different optical path lengths overlap, the state of the wavefront changes for each optical path length difference depending on the degree of the overlap, and on average within the beam cross section. Is reduced in spatial coherence. That is, interference light unnecessary for the exposure apparatus can be eliminated. Also, space in the optical axis direction can be saved. Further, this embodiment has advantages that the configuration is simple and the number of parts is small as compared with the other embodiments described above.

Next, a first modification of the present embodiment shown in FIG. 10 will be described. In this modification, the relative angle between the total reflection mirror 29a and the partial reflection mirror 29b in FIG. 9 is slightly shifted from the parallel direction by an angle α in the direction shown in FIG. As a result, the output beams are not parallel but have an angle with each other, and the adjacent beams Ti and Ti
The interval in the y direction of -1 decreases as i increases, and as a result, the effective diameter of the beam group in the y direction decreases. Therefore, in this modification, in addition to the effect of reducing the coherence, the effect of saving space in the y direction can be obtained. In order to adjust the angle α, for example, a total reflection mirror 2 is formed by an elastic member such as a spring.
9a is urged, and the piezo element is abutted from the opposite side.
Fine adjustment can be performed by appropriately applying a voltage to the piezo element. Alternatively, a micrometer may be used instead of the piezo element. Coarse adjustment may be performed by moving the entire mirror. FIG. 10 is a schematic diagram in which the angles of the light rays and the like are emphasized. In addition, for the sake of simplicity, only a few beams are shown in the figure, the remaining beams are omitted, and the thicknesses of the total reflection mirror 29a and the partial reflection mirror 29b are ignored.

Next, a second modification of the embodiment shown in FIG. 11 will be described. In this modification, as shown in FIG. 9, the distance between the total reflection mirror 29a and the partial reflection mirror 29b is adjusted and arranged almost in parallel with d, and then the total reflection mirror 29 is set.
The deflecting element 23 is inserted between a and the partial reflection mirror 29b. As the deflection element to be inserted, a rectangular diffractive optical element 23 shown in FIG. 2, a blazed diffractive optical element 231 shown in FIG. 3, or a wedge-shaped prism 232 shown in FIG. 4 can be used. . The light is deflected by the deflecting element 23, and the effective diameter of the beam group in the y direction can be reduced as in the first modification. Therefore, in this modification, in addition to the effect of reducing the coherence, the effect of saving space in the y direction can be obtained. In the case of this modification, the adjustment of the total reflection mirror 29a and the partial reflection mirror 29b is facilitated. In particular, when a diffractive optical element is inserted, the wavefront shape changes with each reflection, which is effective for reducing the spatial coherence. Note that, for simplicity, the thickness of the total reflection mirror 29a and the partial reflection mirror 29b is ignored, and the diffractive optical element 23 is schematically illustrated.

Next, a third modification of the embodiment shown in FIG. 12 will be described. In this modification, a total reflection mirror 2 is used instead of inserting the deflection element 23 in the second modification.
A rectangular diffractive optical element 230 is previously provided on the reflection surface 9a. The light is deflected by the diffractive optical element 230, and the effective diameter of the beam group in the y direction can be reduced as in the first modification. Therefore, in this modification, the wavefront shape changes at each reflection, so that the spatial coherence is reduced and the effect of saving space in the y direction is obtained.
In addition, by integrating the total reflection mirror 29a and the diffractive optical element 230 as a deflecting element, the number of components can be reduced as compared with the second modification, and manufacture and adjustment are easy.
The diffractive optical element 230 is not limited to the total reflection mirror 29a but may be provided on the partial reflection mirror 29b. In the figure, for the sake of simplicity, the thicknesses of the total reflection mirror 29a and the partial reflection mirror 29b are ignored, and the diffraction optical element 2
30 is schematically drawn.

Next, an exposure apparatus according to a fifth embodiment of the present invention will be described with reference to FIG. In the example shown in FIG. 13, the optical delay system 20 shown in FIG. 1 is increased by one to further reduce the interference fringes and speckles generated on the reticle and the substrate. Example shown in FIG. 1 and FIG.
Is different between the laser light source 101 such as an excimer laser and the first integrator 171, the depolarizer 103, the relay optical system 102, and the first optical delay unit 1.
04, the second optical delay unit 105, and the beam expander 106. In addition, depolarizer 1
Numeral 03 cancels the influence of the polarized light from the laser light source 101, and is disclosed in, for example, JP-A-11-174365 and JP-A-11-312631.

The laser light from the laser light source 101 passes through a mirror M1, a depolarizer 103, a mirror M2, a relay optical system 102, and a mirror M3 in that order by an optical delay system including two optical delay units (104, 105). A delay action is provided.

Here, the respective optical members constituting the first optical delay unit 104 are predetermined such that the optical path length difference of the laser light applied in the first optical delay unit 104 is longer than the coherence length Lc of the laser light. And the second
Each optical member constituting the second optical delay unit 105 is similar to the optical delay system 20 of FIG. 1 so that the optical path length difference of the laser light provided in the optical delay unit 105 is shorter than the coherence length Lc of the laser. Are arranged in a predetermined relationship. As a result, the second optical delay unit 105 can be made much more compact. Alternatively, the optical path length difference of the laser light provided in the first optical delay unit 104 is configured to be shorter than the coherent distance of the laser light, and the optical path length difference of the laser light applied in the second optical delay unit 105 is provided. May be longer than the coherent distance Lc of the laser beam. Alternatively, it goes without saying that the optical delay unit (104, 105) may be configured such that the optical path length difference of the laser light applied is shorter than the coherence length Lc of the laser light. Note that the optical delay system may be configured to include three or more optical delay units. In this case, the depolarizer 103 can be omitted.

The laser light passing through the optical delay systems (104, 105) is supplied to a mirror M4, a beam expander 106 as a beam shaping optical system, mirrors (M6, M7), an optical integrator system 107, and a condenser optical system 108. The reticle 109 is uniformly illuminated through the reticle 109, and a slit-shaped illumination area is formed on the reticle 109, for example. The partial pattern of the reticle 109 illuminated in a slit shape is projected and exposed on a substrate 111 such as a wafer via a projection optical system 110. In this case, the reticle 109
Is held by a reticle stage (not shown), and the substrate 111 is held by a substrate stage (not shown). The reticle 109 and the substrate 111 are moved in a predetermined direction (the short direction of the slit-shaped illumination area) via the reticle stage and the substrate stage. )
The pattern on the entire surface of the reticle 109 is transferred and exposed on the substrate 111 via the projection optical system 110 by moving the substrate.

The optical integrator system 10
7 has a first integrator 171 and a second integrator 172. In FIG. 13, each integrator (1
71 and 172) are shown as fly-eye lenses, but they may be formed as micro fly-eye lenses, diffractive optical elements, or internal reflection type rod-shaped optical members. Optical integrator system 10
7 and a condenser optical system 108, mirrors (M8, M9) for deflecting the optical path are arranged inside the optical system 107. The mirror M8 inside the optical integrator system 107 is
In order to prevent interference fringes and speckles generated on the reticle 109 and the substrate 111 together with the optical delay systems (104, 105), it is constituted by a vibrating mirror (galvano mirror) that scans reflected light with a very small amount.

The present invention can be applied to each type of illumination optical system for exposure.
1014196A2 (release date: June 28, 2000)
Can be applied to the device disclosed in US Pat. European Patent Publication E
The device disclosed in P1014196A2 includes an orbicular ratio variable optical system that continuously varies an orbicular ratio in orbicular illumination,
Variable optical system for continuously varying the illumination σ value, and further comprises a combination of a plurality of microlens arrays, diffractive optical elements, prisms, fly-eye lenses, glass rods and the like. In the above-mentioned European Patent Publication, the optical delay system (20, 29, 10
4, 105) are the optical path between the light source 1 in FIG. 1 and the interchangeable microlens array (4, 40), and the optical path between the light source 1 and the axicon prism (6, 6a) in FIG. 16 and the diffractive optical element (6b,
6c), the optical path between the light source 1 and the diffractive optical element 6b in FIG. 21, the optical path between the light source 1 and the axicon prism (6, 6a) in FIG. 22, and the light source 601 in FIG. FIG. 2 shows an optical path between the optical element and the diffractive optical element 604.
9, optical elements (751 to 751) replaceable with the light source 701.
756), a diffractive optical element (1004, 1004b, 10) that can be replaced with the light source 1001 in FIG.
04c).

The optical delay system of the present invention (20, 29, 1)
04, 105) is also applicable to the apparatus disclosed in Japanese Patent Application Laid-Open No. 11-271719 (publication date: October 8, 1999). In the device disclosed in Japanese Patent Application Laid-Open No. 11-271719, for example, as shown in FIG.
A variable zone ratio system 3 that imparts the function of converting the exposure light into an annular light beam having a predetermined annular ratio, and the function of converting the exposure light into a quadrupolar light beam and adjusts the position of the quadrupolar light beam. It has a configuration including a possible quadrupole beam variable system 4 and an optical integrator (such as an internal reflection type integrator). In Japanese Unexamined Patent Application Publication No. 11-271719, the optical delay system (20, 29, 104, 105) of the present invention is shown in FIG.
In the optical path or the like between the light source 1 and the orbicular zone ratio variable system 3.

FIG. 14 is a flowchart showing an example of an operation when manufacturing a micro device using the exposure apparatus having the illumination optical device according to each embodiment of the present invention described above. First, in step 101, a metal film is deposited on one lot of wafers. Next Step 10
In 2, the photoresist is applied on the metal film on the wafer of the lot. Thereafter, in step 103, the reticle (60, 10
9) The pattern image is sequentially exposed and transferred to each shot area on the wafer (W, 111) of the lot through the projection system. Thereafter, in step 104, the photoresist on the one lot wafer is developed, and in step 105, the pattern on the reticle 60 is etched by etching the one lot wafer using the resist pattern as a mask. Is formed in each shot area on each wafer. Thereafter, by forming a circuit pattern on a further upper layer, a device such as a semiconductor element having an extremely fine circuit is manufactured.

Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and it is obvious that the technical scope of the present invention is not limited thereto. It is understood that it belongs to.

[0056]

As described in detail above, according to the present invention, the illumination optical device and the illumination optical device which can reduce the coherence of the light source and reduce the size of the device can be provided as in the prior art. Exposure apparatus can be provided. Furthermore, the complicated work of finely adjusting the mirror angle, which was conventionally required, is not required, and the desired light deflection angle can be easily set.
An illumination optical device which is easy to manufacture and an exposure apparatus having the illumination optical device can be provided. According to another aspect of the present invention, it is possible to provide a method for manufacturing a micro device using the exposure apparatus.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a cross-sectional shape of the deflection element according to the embodiment of the present invention.

FIG. 3 is a diagram showing a cross-sectional shape of the deflection element according to the embodiment of the present invention.

FIG. 4 is a diagram showing a cross-sectional shape of the deflection element according to the embodiment of the present invention.

FIG. 5 is a configuration diagram of an optical delay system according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of an optical delay system according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a cross-sectional shape of the transmission optical element according to the embodiment of the present invention.

FIG. 8 is a configuration diagram of an optical delay system according to a fourth embodiment of the present invention.

FIG. 9 is a diagram illustrating the principle of an optical delay system according to a fourth embodiment of the present invention.

FIG. 10 is a diagram illustrating a first modification of the fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating a second modification of the fourth embodiment of the present invention.

FIG. 12 is a diagram illustrating a third modification of the fourth embodiment of the present invention.

FIG. 13 is a configuration diagram of an exposure apparatus according to a fifth embodiment of the present invention.

FIG. 14 is a flowchart illustrating an example of a method for manufacturing a micro device according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 light source 20 optical delay system 21 half mirror 23 deflecting element 24 polarizing beam splitter 25 a, 25 b lens 26 a, 26 b λ / 2 plate 27 tilt mirror 28 random phase plate 29 multi-beam optical system 30 light guide system 40 optical integrator system 50 condenser optical Series 60 reticle

Claims (17)

[Claims] 1. A light source for supplying coherent light, an optical path length shorter than a coherent distance of the coherent light between the plurality of split lights and a plurality of split lights generated by dividing the coherent light. An illumination optical device, comprising: an optical delay system for providing a difference; and a light guide system for guiding light from the optical delay system to a surface to be irradiated. 2. An optical path length difference between an n-th divided light and an (n + 1) -th divided light traveling on an optical path next to the n-th divided light, where n is an integer equal to or greater than zero. The illumination optical device according to claim 1, wherein the distance is set shorter than the coherent distance of the coherent light. 3. The optical delay system according to claim 1, further comprising a transmission type deflection element for deflecting incident light.
Or the illumination optical device according to 2. 4. A light source that supplies coherent light, an optical delay system that divides the coherent light to generate a plurality of divided lights, and provides a predetermined optical path length difference between the plurality of divided lights; A light guide system for guiding light from the optical delay system to a surface to be illuminated, wherein the optical delay system includes a transmission type deflection element for deflecting incident light. 5. The illumination optical device according to claim 3, wherein the transmission type deflection element is an element having a different optical path length depending on a portion. 6. The transmission type deflection element according to claim 5, wherein when λ is the wavelength of the coherent light, the transmission type deflection element has a portion where an optical path length difference is larger than λ / 10. Illumination optics. 7. The transmission type deflecting element has a plurality of portions having different optical path lengths, and the size of the portions is not more than の of the spatial coherence of the coherent light. The illumination optical device according to any one of claims 3 to 6, wherein: 8. The optical delay system, comprising: a light splitting unit that splits the coherent light to generate the plurality of split lights;
The illumination optical device according to any one of claims 1 to 7, further comprising a light mixing unit that mixes the plurality of divided lights and guides the split light to the light guide system. 9. The light splitting means has a light splitting surface which also serves as the light mixing means, and the optical delay system returns the light split by the light splitting surface to the light splitting surface again. And a circular optical path forming means having a plurality of deflecting surfaces, wherein each deflecting surface in the circular optical path forming means is set to give the optical path length difference. An illumination optical device according to claim 8. 10. The optical delay system includes a reflecting surface and a light splitting surface facing the reflecting surface, wherein the reflecting surface and the light splitting surface are located between the reflecting surface and the light splitting surface. 2. The multi-reflecting device according to claim 1, wherein an optical path length difference shorter than the coherent distance is provided between split light beams from the light splitting surface toward the light guide system.
The illumination optical device according to any one of items 1 to 7. 11. The illumination optical device according to claim 10, wherein the reflection surface and the light dividing surface are arranged non-parallel. 12. The illumination optical device according to claim 10, wherein the optical delay system further includes a deflection element disposed between the reflection surface and the light division surface. 13. A light source for providing coherent light,
An optical delay system that splits the coherent light to generate a plurality of split light beams and imparts a predetermined optical path length difference between the plurality of split light beams, and a light guide that guides light from the optical delay system to a surface to be irradiated. An illumination optical device, comprising: an optical system, wherein the optical delay system includes a reflective deflecting element capable of deflecting light and adjusting a deflection angle, and a transmission optical element for diffusing or diffracting light. 14. The illumination optical device according to claim 13, wherein the predetermined optical path length difference is shorter than a coherent distance of the coherent light. 15. The light guide system has an optical integrator system for generating a secondary light source in order to uniformly illuminate the irradiation surface, and the optical integrator system includes the secondary light source. 15. The image forming apparatus according to claim 1, wherein 10,000 or more light source images are formed on the substrate.
Item 15. The illumination optical device according to Item 1. 16. An illumination optical system comprising the illumination optical device according to any one of claims 1 to 15, a mask holding means for setting a mask having a predetermined pattern on the surface to be irradiated, and a mask holding means for setting the mask. An exposure apparatus comprising: a projection optical system for projecting a pattern image onto a photosensitive substrate; and substrate holding means for holding the photosensitive substrate. 17. A method for manufacturing a micro device using the exposure apparatus according to claim 16, wherein a step of applying a photosensitive material on the photosensitive substrate and a step of applying the projection optical system on the photosensitive substrate are performed. A method of projecting an image of the pattern of the mask through a mask, and a step of developing the photosensitive material on the photosensitive substrate.