JP2002222761A - Illuminating optical device and aligner provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminating optical device which can change the conditions of illumination almost continuously without substantially losing the quantity of light in a wave front split optical integrator. SOLUTION: An illuminating optical device for illuminating a surface (M) to be irradiated on the basis of a luminous flux from a light source (1) is provided with a wave front split optical integrator (6), which is arranged in an optical path between the light source and the surface to be irradiated and has a multitude of two-dimensionally arranged microscopic lens elements, and a light-leading optical system (7) arranged in an optical path between the optical integrator and the surface to be irradiated. A prescribed shape of a secondary light source, which is used as a virtual image, is formed at the position of the incident surface of the optical integrator via a relay optical system (5).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical apparatus and an exposure apparatus provided with the illumination optical apparatus. The present invention relates to an illumination optical device suitable for an exposure apparatus.

[0002]

2. Description of the Related Art In a typical exposure apparatus of this kind,
The light beam emitted from the light source enters the fly-eye lens via the relay optical system, and forms a secondary light source including a large number of light sources on the rear focal plane. The light beam from the secondary light source is restricted via an aperture stop arranged near the rear focal plane of the fly-eye lens, and then enters the condenser lens. The aperture stop limits the shape or size of the secondary light source to a desired shape or size according to a desired illumination condition (exposure condition).

A light beam condensed by a condenser lens illuminates a mask on which a predetermined pattern is formed in a superimposed manner. Light transmitted through the pattern of the mask forms an image on the wafer via the projection optical system. Thus, on the wafer,
The mask pattern is projected and exposed (transferred). The pattern formed on the mask is highly integrated, and it is indispensable to obtain a uniform illuminance distribution on the wafer in order to accurately transfer the fine pattern onto the wafer.

In recent years, illumination coherency σ (σ) has been changed by changing the size of the aperture (light transmitting portion) of an aperture stop arranged on the exit side of a fly-eye lens.
Value = aperture stop diameter / pupil diameter of projection optical system, or σ value = exit side numerical aperture of illumination optical system / incident side numerical aperture of projection optical system)
Attention has been focused on technologies that change the temperature. In addition, by setting the shape of the opening of the aperture stop arranged on the emission side of the fly-eye lens to a ring shape or a four-hole shape (that is, a quadrupole shape), the secondary light source formed by the fly-eye lens is formed. Attention has been paid to a technology for improving the depth of focus and the resolving power of a projection optical system by limiting the shape to an annular shape or a quadrupole shape.

By the way, if the σ value is changed by changing only the size of the aperture of the aperture stop without changing the size of the secondary light source formed by the fly-eye lens, light loss occurs in the aperture stop. . Therefore, for example, by changing the focal length of the relay optical system, the size of the secondary light source formed by the fly-eye lens is changed, and in conjunction with the change in the size of the secondary light source, the aperture of the aperture stop is changed. Techniques for changing the size have been proposed. In this case, as the focal length of the relay optical system changes, the numerical aperture of the light beam incident on the fly-eye lens changes. In addition, when performing deformed illumination in which the shape of the secondary light source is limited to an annular shape or a quadrupolar shape, it is not possible to manufacture a variable stop for continuously changing the annular or quadrupolar secondary light source. It was not easy. Further, in order to prevent uneven illumination, it is necessary to irradiate the entirety of the entrance surface of each lens element of the fly-eye lens overlapping the opening of the variable stop with illumination light.

[0006]

In the prior art as described above, a large number of light sources discretely formed on the rear focal plane of the fly-eye lens constitute a secondary light source. In this case, when the numerical aperture of the light beam incident on the fly-eye lens becomes relatively small due to the change in the focal length of the relay optical system, the size of each light source formed is reduced, and the overall area of the secondary light source is reduced. , The ratio of the area occupied by a large number of light sources decreases. As a result, even if the size of the aperture of the aperture stop is changed continuously, the size of the secondary light source limited by the aperture stop changes discontinuously (stepwise).

On the other hand, if the numerical aperture of the light beam incident on the fly-eye lens becomes relatively large in accordance with the change in the focal length of the relay optical system, a light quantity loss occurs in each lens element constituting the fly-eye lens. Further, in the related art, it is not practical to continuously change the shape of the secondary light source during deformed illumination because it is difficult to manufacture a variable stop. Further, in the prior art, the incidence surface of the fly-eye lens needs to be illuminated sufficiently large in order to prevent the occurrence of illumination unevenness. As described above, in the conventional technique, there is a disadvantage that the illumination condition cannot be changed almost continuously without substantially losing the light amount in the fly-eye lens as the wavefront division type optical integrator.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides an illumination optical apparatus capable of changing illumination conditions almost continuously without substantial loss of light quantity in a wavefront splitting optical integrator. And an exposure apparatus provided with the illumination optical device. Further, the present invention provides a method of manufacturing a micro device capable of manufacturing a good micro device under a good lighting condition using an exposure apparatus capable of changing a lighting condition almost continuously. The purpose is to:

[0009]

According to a first aspect of the present invention, there is provided an illumination optical apparatus for illuminating a surface to be illuminated based on a light beam from a light source. Arranged in the optical path between the irradiation surface and the optical integrator of the wavefront division type having a large number of two-dimensionally arrayed minute lens elements, in the optical path between the optical integrator and the irradiated surface An illumination optical device, comprising: a light guide optical system disposed therein; and a secondary light source having a predetermined shape as a virtual image is formed at a position of an incident surface of the optical integrator.

[0010] According to a preferred aspect of the first invention, the maximum incident angle of the light beam incident on the optical integrator is such that the exit surface of the optical integrator is 60%.
It is set to be illuminated at the above ratio.

According to a preferred aspect of the first invention,
A light beam conversion element disposed in an optical path between the light source and the optical integrator to convert a substantially parallel light beam from the light source into a light beam having a predetermined cross-sectional shape or a light beam having a predetermined light intensity distribution; Is disposed in an optical path between the light beam conversion element and the optical integrator, and forms the secondary light source as a virtual image at the incident surface position of the optical integrator based on the light beam passing through the light beam conversion element. And a relay optical system.

In this case, the light beam conversion element is disposed near a front focal plane of the relay optical system, and an exit surface position of the optical integrator is disposed near a rear focal plane of the relay optical system. The exit surface of the optical integrator is disposed approximately optically conjugate with the light beam conversion element via the relay optical system, and the incident surface of the optical integrator is disposed via the light guide optical system and the optical integrator. It is preferable that they are arranged almost optically conjugate with the surface to be irradiated. In this case, the relay optical system is configured as a variable power optical system having a variable focal length in order to change the overall size of the secondary light source formed as a virtual image at the position of the incident surface of the optical integrator. Is preferred.

[0013] Further, the size of the light emitting portion of the light beam converting element is d, the focal length of the relay optical system is fr, so that the exit surface of the optical integrator is illuminated at a ratio of 80% or more. The focal length of each microlens element constituting the optical integrator is represented by fe.
And when the size of each minute lens element is de, d
It is preferable to satisfy the condition of> 0.8 · (fr / fe) de. In this case, it is preferable to include a light emitting portion changing unit for changing the size d of the light emitting portion of the light beam conversion element. Further, in this case, the light emitting portion changing means has an afocal zoom lens arranged on the light source side of the light beam conversion element and for adjusting a size of a cross section of the light beam incident on the light beam conversion element. Is preferred.

According to a preferred aspect of the first invention, the light source is disposed in an optical path between the light source and the optical integrator, and converts the substantially parallel light beam from the light source into a light beam having a predetermined sectional shape or a predetermined light beam. A light beam conversion element for converting the light beam into a light beam having a light intensity distribution, and a light beam conversion element disposed in an optical path between the light beam conversion element and the optical integrator to guide the light beam via the light beam conversion element to a predetermined surface. A first relay optical system, a light beam diverging element positioned on the predetermined surface to diverge the light beam incident through the first relay optical system, and an optical path between the light beam diverging element and the optical integrator A second relay optical system arranged inside the optical system to optically substantially conjugate the light diverging element and the exit surface position of the optical integrator Having.

In this case, the light beam conversion element is provided with the first
It is preferable that the luminous flux diverging element is disposed near a front focal plane of the relay optical system, and that the light diverging element is disposed near a rear focal plane of the first relay optical system. In this case, in order to change the overall size of the secondary light source formed as a virtual image at the position of the incident surface of the optical integrator, the first relay optical system is a variable power optical system having a variable focal length. Preferably, it is configured.

Further, the maximum exit angle of the light beam emitted from the light beam diverging element is set to θb, and the imaging magnification of the second relay optical system is set so that the light exit surface of the optical integrator is illuminated at a ratio of 80% or more. β, the focal length of each minute lens element constituting the optical integrator is fe, and the size of each minute lens element is d.
e, θb> 0.8 · sin ^-1 (| β | · de /
It is preferable that the condition of fe) is satisfied. In this case, in order to suppress a change in the maximum emission angle θb of the light beam emitted from the light beam diverging element due to a change in the focal length of the first relay optical system, the maximum incident angle θa of the light beam incident on the light beam diverging element is , Is preferably set substantially smaller than the maximum emission angle θb. These light beam conversion elements and light beam diverging elements preferably include a diffractive optical element, a micro prism array, or a micro fly's eye lens. Further, it is preferable that the incident surface of the optical integrator is substantially optically conjugate with the irradiated surface.

According to a second aspect of the present invention, there is provided the illumination optical device according to the first aspect, and a projection optical system for projecting and exposing a mask pattern set on the surface to be irradiated onto a photosensitive substrate. An exposure apparatus is provided.

In a third aspect of the present invention, an exposure step of exposing the pattern of the mask onto the photosensitive substrate by the exposure apparatus of the second invention, and a developing step of developing the photosensitive substrate exposed in the exposure step And a method for manufacturing a microdevice.

[0019]

DETAILED DESCRIPTION OF THE INVENTION In a typical embodiment of the invention,
A substantially parallel light beam from a light source such as an excimer laser light source is converted into, for example, a circular light beam through a diffractive optical element as a light beam conversion element. The circular luminous flux formed through the diffractive optical element passes through the relay optical system and the optical integrator itself, and enters a circular image as a virtual image at the incident surface position of a wavefront splitting optical integrator such as a fly-eye lens. Form a secondary light source. The light beam from the circular secondary light source circularly illuminates an irradiated surface such as a mask via the light guide optical system.

As described above, in the present invention, unlike the prior art in which a large number of light sources discretely formed on the rear focal plane of the fly-eye lens constitute a secondary light source, the light source is disposed on the entrance surface of the fly-eye lens. A secondary light source as a surface light source having a predetermined shape is formed as a virtual image. Therefore, if the exit surface of the fly-eye lens is illuminated at a predetermined ratio, the illumination condition can be changed almost continuously without substantial loss of light amount in the fly-eye lens.

Therefore, in the exposure apparatus incorporating the illumination optical device of the present invention, the illumination condition can be changed almost continuously without substantial loss of the light amount in the fly-eye lens. Thus, a good microdevice can be manufactured with high throughput.

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of an exposure apparatus including an illumination optical device according to the first embodiment of the present invention. FIG. 2 is an enlarged view schematically showing a main part configuration from a diffractive optical element to an illumination field stop (mask blind) in the exposure apparatus of FIG. In FIG. 1, the Z axis is along the normal direction of the wafer W which is a photosensitive substrate, the Y axis is in the direction parallel to the plane of FIG. The X axis is set in each direction.

The exposure apparatus shown in FIG. 1 uses, for example, 248 nm (Kr) as a light source 1 for supplying exposure light (illumination light).
F) or an excimer laser light source for supplying light having a wavelength of 193 nm (ArF). A substantially parallel light beam emitted from the light source 1 along the Z direction has a rectangular cross section elongated in the X direction, and enters a beam expander 2 including a pair of lenses 2a and 2b. Each lens 2a and 2b is in the plane of the paper of FIG. 1 (in the YZ plane).
Has a negative refractive power and a positive refractive power, respectively. Therefore, the light beam incident on the beam expander 2 is enlarged in the plane of FIG. 1 and shaped into a light beam having a predetermined rectangular cross section.

A substantially parallel light beam passing through a beam expander 2 as a shaping optical system is deflected in the Y direction by a bending mirror 3 and then enters a diffractive optical element (DOE) 4. The diffractive optical element 4 is formed, for example, by forming a step having a pitch of about the wavelength of exposure light (illumination light) on a glass substrate, and has an action of diffracting an incident beam to a desired angle. Specifically, the diffractive optical element 4 converts a rectangular incident light beam into a circular light beam centered on the optical axis AX.

A light beam passing through a diffractive optical element 4 serving as a light beam converting element passes through a relay optical system 5 to a fly-eye lens 6 serving as a wavefront splitting optical integrator.
Incident on. The fly-eye lens 6 is formed by arranging a large number of lens elements having a positive refractive power vertically and horizontally and densely. Each lens element is configured such that the rear focal plane substantially coincides with the exit plane, and the front focal plane substantially coincides with the entrance plane.

Further, as shown in FIG.
Are arranged so that the front focal plane of the optical element 4 coincides with the diffraction plane of the diffractive optical element 4, and the rear focal plane of the relay optical system 5 coincides with the exit plane position of the fly-eye lens 6. Therefore, a circular far-field pattern is formed by the relay optical system 5 at the exit surface position of the fly-eye lens 6. In this specification, the exit surface and the exit surface position are clearly distinguished. In FIG. 2, the diffractive optical element 4 as a light beam converting element and the exit surface of the fly-eye lens 6 are conjugate, and the diffractive optical element 4 forms an image on the exit surface of the fly-eye lens 6. On the other hand, the position of the exit surface of the fly-eye lens 6 is located at the rear focal point of the relay optical system 5. As a result, light is condensed at the center of the fly-eye lens 6 as shown in FIG. That is, in the example of FIG. 2, the exit surface 6a of the fly-eye lens 6 itself is not located at the rear focal point of the relay optical system 5, but the exit surface position of the fly-eye lens 6 is located at the rear focal position of the relay optical system 5. It is in. Here, the fly-eye lens 6
In consideration of the refractive index n of each lens element, the thickness (length along the optical axis) of each lens element is represented by t.
A far field pattern is formed at a position of t / n from the incident surface of the fly-eye lens 6. Further, since the diffractive optical element 4 as a light beam converting element is located at the front focal position of the relay optical system 5, the light beam illuminating the fly-eye lens 6 is basically a telecentric light beam.

The light beam that has passed through the fly-eye lens 6 illuminates the mask blind 8 as an illumination field stop through a condenser lens 7 in a superimposed manner. Here, as shown in FIG. 2, the front focal plane of the condenser lens 7 and the incident plane position of the fly-eye lens 6 coincide, and the rear focal plane of the condenser lens 7 and the mask blind 8 coincide. Are located. Then, the diffractive optical element 4
And the exit surface of the fly-eye lens 6 are arranged optically conjugate via the relay optical system 5. Also,
The entrance surface of the fly-eye lens 6 and the mask blind 8 are optically conjugate via a condenser lens 7. In this specification, the incident surface and the incident surface position are clearly distinguished. When the parallel light beam indicated by the broken line in FIG. 2 is traced backward from the mask blind 8 side, this parallel light beam is not the incident surface of the fly-eye lens 6 but the fly-eye lens 6 Focus on the center of That is, in the example of FIG. 2, the incident surface 6b of the fly-eye lens 6 itself is not at the front focal point of the condenser lens 7,
The incident surface position of the fly-eye lens 6 is at the front focal position of the condenser lens 7.

Therefore, a predetermined light intensity distribution is formed on the exit surface of the fly-eye lens 6, as shown by the solid line portion 6a in FIG. As a result, as shown by a broken line portion 6b in FIG. 2, the incident surface position of the fly-eye lens 6 is seen from the condenser lens 7 as if a secondary light source having a circular shape was formed. In other words, a circular secondary light source 6b as a virtual image is formed at the entrance surface position of the fly-eye lens 6. Hereinafter, this point will be described with reference to FIG.

In FIG. 3, it is assumed that one point of the light source is formed at the center point B of the exit surface of the lens element e1 on the upper side in the figure. In this case, when the light ray is traced, the light is seen from the condenser lens 7 as if the light is emitted from the center point A of the incident surface of the lens element e1. On the other hand, it is assumed that one point of the light source is formed at a point B ′ deviating from the center point of the exit surface of the lens element e2 on the lower side in the figure. Also in this case, when the ray is traced, the lens element e
The light can be seen from the condenser lens 7 as if light is emitted from a point A ′ opposite to the point B ′ on the incident surface 2.

Further, as described above, the incident surface of the fly-eye lens 6 is arranged optically conjugate with the mask blind 8, but considering the corresponding three points a, b and c, the point B It can be seen that the light incident on A and B 'exits at the same angle from points A and A'. That is, a circular secondary light source as a virtual image is formed at the position of the incident surface of the fly-eye lens 6 corresponding to the light intensity distribution formed on the exit surface of the fly-eye lens 6. For this reason,
The position of the incident surface of the fly-eye lens 6 is set as the surface on which the secondary light source is formed, and the mask blind 8 may be illuminated via the condenser lens 7. In addition, from FIG.
Is formed at the center of the lens element of the fly-eye lens 6. Therefore, in consideration of laser resistance, the fly-eye lens 6 is divided into
It is preferable to position the laser focal point between the divided lens elements.

The light beam passing through the rectangular opening (light transmitting portion) of the mask blind 8 is condensed by the imaging optical system 9 and then superimposed on the mask M on which a predetermined pattern is formed. Light up. Thus, the imaging optical system 9 forms an image of the rectangular opening of the mask blind 8 on the mask M. The light flux transmitted through the pattern of the mask M forms an image of the mask pattern on the wafer W as a photosensitive substrate via the projection optical system PL. Thus, the projection optical system P
By performing collective exposure or scan exposure while driving and controlling the wafer W two-dimensionally on a plane (XY plane) orthogonal to the optical axis AX of L, the pattern of the mask M is sequentially formed in each exposure area of the wafer W. Exposed. Here, the incident surface of the fly-eye lens 6 is almost optically conjugate with the mask and the mask conjugate surface (mask blind 8, wafer W) as the surface to be irradiated, and no illumination unevenness occurs here. .

In the batch exposure, a so-called step
According to the AND-repeat method, the mask pattern is collectively exposed to each exposure region of the wafer. In this case, the shape of the illumination area on the mask M is a rectangular shape close to a square, and the cross-sectional shape of each lens element of the fly-eye lens 6 is also a rectangular shape close to a square. On the other hand, in scan exposure, according to a so-called step-and-scan method, a mask pattern is scanned and exposed on each exposure region of a wafer while the mask and wafer are relatively moved with respect to a projection optical system. In this case, the shape of the illumination area on the mask M is such that the ratio of the short side to the long side is, for example, 1: 3.
, And the cross-sectional shape of each lens element of the fly-eye lens 6 is also similar to this.

Here, it is important when printing a fine pattern that the flatness of the circular shape (light source shape) of the illuminating light beam incident on the irradiated surface (mask surface and wafer surface) is about 1% or less. . Further, it is desirable to avoid as much as possible that the shape of the illumination light flux varies depending on the incident position on the surface to be irradiated. Therefore, in FIG. 3, the entire area between the point B on the exit surface of the upper end lens element e1 and the point B ′ on the exit surface of the lower lens element e2 constituting the fly-eye lens 6 is completely ( That is, it is desirable that the light be fully illuminated.

On the other hand, in order to change the illumination conditions, the focal length of the relay optical system 5 is changed, and the fly-eye lens 6 is changed.
What is necessary is just to change the size of the circular secondary light source (virtual image) formed on the incident surface of. However, in this case, when the NA (numerical aperture) of the light beam incident on the fly-eye lens 6 decreases with a change in the focal length of the relay optical system 5, the exit surface of the fly-eye lens 6 is not completely illuminated. Even if the size of the secondary light source is continuously changed, the change in the shape of the light source (and, consequently, the change in the illumination condition) is discontinuous.

As described above, in order to continuously change the shape of the light source, it is desirable that the entire exit surface of the fly-eye lens 6 is illuminated. However, in practice, if the exit surface of the fly-eye lens 6 is illuminated at a rate of 60% or more, preferably at a rate of 80% or more, the shape of the light source is changed almost continuously, and the illumination condition is almost changed. It can be changed continuously. In order for the exit surface of the fly-eye lens 6 to be illuminated at a ratio of 80% or more, the following conditional expressions (1) and (2) must be satisfied.

D1> 0.8 · (fr / fe) de1 (1) d2> 0.8 · (fr / fe) de2 (2) where d1 is the X-direction of the light emitting portion of the diffractive optical element 4. Where d2 is the size of the light emitting portion of the diffractive optical element 4 in the Z direction. Also, fr is the focal length of the relay optical system 5, and fe is the focal length of each lens element of the fly-eye lens 6. Further, de1 is the size of each lens element in the X direction, and de2 is the size of each lens element in the Z direction.

Referring to conditional expressions (1) and (2),
It is understood that the cross-sectional shape of the light beam incident on the diffractive optical element 4 and the cross-sectional shape of each lens element are preferably similar. For example, when the illumination area of the mask is elongated due to the scanning exposure, that is, when the cross-sectional shape of the lens element is elongated, the conditional expressions along the longitudinal direction among the conditional expressions (1) and (2) are important. become.

Here, as described above, in order to continuously change the size of the secondary light source, it is necessary to change the focal length of the relay optical system 5 continuously. However, if the focal length fr of the relay optical system 5 changes, the conditional expressions (1) and (2) cannot be satisfied, and the light source shape may not be able to be changed almost continuously. In this case, for example, as shown in a modification of FIG.
1, the focal length fr of the relay optical system 5 is changed and the magnification of the afocal zoom lens 11 is changed so as to always satisfy the conditional expressions (1) and (2). Size of light emitting part (d1 × d2)
Is desirably changed.

FIGS. 5 to 7 are views showing a circular secondary light source as a virtual image formed on the incident surface of the fly-eye lens. Here, FIG. 5 shows the smallest circular secondary light source in a so-called small σ state. Also, FIG.
The largest circular secondary light source in a so-called large σ state is shown. FIG. 6 shows a circular secondary light source having an intermediate size in a so-called middle σ state.

As described above, in the first embodiment, unlike the prior art in which a large number of light sources discretely formed on the rear focal plane of the fly-eye lens constitute a secondary light source, the fly-eye lens 6 A secondary light source as a circular surface light source is formed as a virtual image on the incident surface. Therefore, if the exit surface of the fly-eye lens 6 is illuminated at a predetermined ratio, for example, a ratio of 80% or more, it is possible to substantially continuously change the illumination condition without substantially losing the light amount in the fly-eye lens 6. Can be.

Specifically, in the first embodiment, by changing the focal length fr of the relay optical system 5 so as to always satisfy the conditional expressions (1) and (2), the fly-eye lens 6 is substantially changed. The value of σ in circular illumination, and thus the illumination conditions, can be changed almost continuously without loss of light quantity. Also, in the first embodiment, unlike the related art, an aperture stop for limiting the secondary light source is not required.

In the first embodiment, the diffractive optical element 4
Instead of, for example, European Patent Publication No.
A micro prism array disclosed in FIGS. 23 to 28 of the publication, a micro fly's eye lens disclosed in FIG. 2 of the publication, and the like can also be used. Further, in the first embodiment, the present invention is described by taking the case of circular illumination as an example. However, instead of the diffractive optical element 4, a diffractive optical element for annular illumination or a quadrupole illumination is used. By forming an annular secondary light source or quadrupolar secondary light source, deformed illumination such as annular illumination or quadrupole illumination can also be performed. These points are the same in other embodiments described later.

FIG. 8 is a view schematically showing a main configuration of an exposure apparatus provided with an illumination optical device according to a second embodiment of the present invention. FIG. 8 does not show a portion from the light source 1 to the bending mirror 3 in FIG. 1 and a portion from the condenser lens 7 to the wafer W in FIG. That is, the second embodiment has a form in which the diffractive optical element 4 and the relay optical system 5 in the first embodiment are replaced by the first diffractive optical element 20 and the second relay optical system 24. Hereinafter, the second embodiment will be described focusing on the differences from the first embodiment.

In the second embodiment, a substantially parallel light beam from the light source 1 enters the first diffractive optical element 20. The first diffractive optical element 20 has the same function as the diffractive optical element 4 in the first embodiment. Therefore, the first diffractive optical element 2
The light beam emitted with a predetermined angular distribution from 0 passes through the first relay optical system 21 having the same function as the relay optical system 5 in the first embodiment, and the second diffractive optic positioned at the rear focal plane. A circular light intensity distribution is formed on the element 22. The light beam passing through the second diffractive optical element 22 as the light beam diverging element is incident on the fly-eye lens 6 via the second relay optical system 24 having a fixed focal length after being restricted by the aperture stop 23.

Here, the second diffractive optical element 22 and the exit surface position of the fly-eye lens 6 are optically conjugate via a second relay optical system 24. In other words, the second
The light emitting portion of the diffractive optical element 22 is configured to form an image at the exit surface position of the fly-eye lens 6 via the second relay optical system 24. Therefore, in the second embodiment, similarly to the first embodiment, a circular secondary light source as a virtual image is formed at the position of the incident surface of the fly-eye lens 6.
In the second embodiment, since the first diffractive optical element 20 as the light beam converting element is located at the front focal position of the first relay optical system 21, the second diffractive optical element 22 as the light beam diverging element is telecentrically illuminated. . Since the second relay optical system 24 is telecentric toward the fly-eye lens 6 (both sides are telecentric in this embodiment), the light from the second diffractive optical element 22 illuminates the fly-eye lens 6 with telecentric illumination.

In the second embodiment, in order for the entire exit surface of the fly-eye lens 6 to be illuminated densely, the maximum incident angle of the light beam incident on the fly-eye lens 6 along the X direction is required. θc1 and the maximum incident angle θc2 along the Z direction must satisfy the following conditional expressions (3) and (4), respectively. sin (θc1)> de1 / (2 · fe) (3) sin (θc2)> de2 / (2 · fe) (4) Here, as described above, de1 is the size of each lens element in the X direction. And de2 is the size of each lens element in the Z direction. Fe is the focal length of each lens element of the fly-eye lens 6.

In actuality, as described above, the exit surface of the fly-eye lens 6 has a ratio of 60% or more, preferably 80%.
When the light is illuminated at a ratio of not less than%, the shape of the light source can be changed almost continuously, and the lighting conditions can be changed almost continuously. In order to illuminate the exit surface of the fly-eye lens 6 at a ratio of 80% or more in the second embodiment,
The maximum emission angle θb1 along the X direction and the maximum emission angle θb2 along the Z direction of the light beam emitted from the second diffractive optical element 22 need to satisfy the following conditional expressions (5) and (6).

Θb1> 0.8 · sin ⁻¹ (| β | · de1 / fe) (5) θb2> 0.8 · sin ⁻¹ (| β | · de2 / fe) (6) where β is , The imaging magnification of the second relay optical system 24.

In the case of the second embodiment, when the focal length of the first relay optical system 21 is changed to change the illumination condition, the maximum incident angle θa of the light beam incident on the second diffractive optical element 22 also changes. I will. As a result, the second diffractive optical element 2
2, the maximum exit angle θb from the second diffractive optical element 22 also changes, and it may not always be possible to satisfy the conditional expressions (5) and (6). In this case, by suppressing the variation of the maximum incident angle θa due to the change in the focal length of the first relay optical system 21, that is, by suppressing the value of the maximum incident angle θa itself, the variation of the maximum exit angle θb is reduced. It is preferable to suppress.

That is, in the second embodiment, to change the illumination condition almost continuously by changing the focal length of the first relay optical system 21 while always satisfying the conditional expressions (5) and (6), It is preferable to satisfy the following conditional expression (7). θa <(１ ／) · θb (7) In order to more reliably change the illumination condition almost continuously, the coefficient of θb on the right side of the conditional expression (7) is set to 1/5.
It is preferable to set

Further, in the second embodiment, an afocal zoom lens as shown in FIG. A configuration for adjusting the diameter of the incident light beam is also possible. With this configuration, regardless of the change in the focal length of the first relay optical system 21, the second diffractive optical element 22
The maximum incident angle θa to the second diffractive optical element 22 is kept constant, and the maximum exit angle θb from the second diffractive optical element 22 is kept constant.
Conditional expressions (5) and (6) can always be satisfied.

Further, in FIG. 8, the second relay optical system 24
Although the absolute value of the imaging magnification β is shown to be larger than 1, this is not a necessary condition for the second embodiment.
The optimum imaging magnification β of the second relay optical system 24 is determined by the divergence performance of the second diffractive optical element 22. Therefore, the absolute value of the imaging magnification β of the second relay optical system 24 becomes |
β | = 1 or | β | <1.

Further, in the second embodiment, a micro prism array, a fly-eye lens, or the like can be used instead of the second diffractive optical element 22. As shown in FIG. 9, in the case of the modification in which the fly-eye lens 25 is used instead of the second diffractive optical element 22, the fly-eye lens 2 when the exit surface of the fly-eye lens 25 is illuminated at the maximum incident angle θa
5 depends only on the shape parameters of the fly-eye lens 25.

That is, in the modification of the second embodiment shown in FIG. 9, since the maximum exit angle θb does not vary depending on the maximum incident angle θa, the conditional expressions (5) and (6)
The illumination condition can be changed almost continuously by changing the focal length of the first relay optical system 21 while always satisfying the above conditions. In this case, the fly-eye lens 25 is not necessarily required.
It is not necessary that the exit surface of the device be fully illuminated.

Further, in the second embodiment, a so-called axicon is arranged in the optical path between the first relay optical system 21 and the second diffractive optical element 22 to perform annular illumination, quadrupole illumination, and the like. You can also. In this case, the axicon is constituted by a pair of conical prisms (cone-convex prism and conical-concave prism), and by changing the distance between them, the width (difference between the outer diameter and the inner diameter) of the annular secondary light source is made constant. It is possible to change the overall size of the secondary light source while maintaining it. As the axicon, for example, the axicon disclosed in FIG. 43 of European Patent Publication No. 1014196 can be used.

The axicon is composed of a pair of pyramid prisms (a square pyramid convex prism and a regular square pyramid concave prism), and the distance between the prisms is changed so that the size of the four light sources constituting the quadrupole secondary light source is changed. Can be changed while the overall size of the secondary light source is maintained. In this case, by changing the focal length of the first relay optical system 21, it is needless to say that the whole of the annular or quadrupolar secondary light source can be similarly enlarged or reduced. Absent.

FIG. 10 is a view schematically showing a configuration of a main part of an exposure apparatus provided with an illumination optical device according to a third embodiment of the present invention. In FIG. 10, a portion from the light source 1 to the bending mirror 3 in FIG. 1 and a portion from the condenser lens 7 to the wafer W in FIG. 1 are omitted. That is, in the third embodiment, the afocal zoom lens 30 and the second relay optical system 32 are provided in the optical path between the bending mirror 3 and the diffractive optical element 4 in the first embodiment. Hereinafter, the third embodiment will be described focusing on the differences from the first embodiment.

In the third embodiment, after a substantially parallel light beam from the light source 1 is shaped into a cross section of a desired size via the afocal zoom lens 30, the second diffractive optical element 3
Incident on 1. Here, the afocal zoom lens 30
Includes a cylindrical lens, the aspect ratio of the rectangular cross section of the light beam incident on the second diffractive optical element 31 can be changed. The light beam emitted in a circular shape (ring shape or four-point shape) via the second diffractive optical element 31
A circular (ring-shaped or four-point) light intensity distribution is formed on the pupil plane of the relay optical system 32.

In this way, the diffractive optical element 4 is illuminated with a circular (ring or four-point) angular distribution. As described above, the diffractive optical element 4 has an action of radiating an incident light beam in a circular shape. Therefore, the light beam having passed through the diffractive optical element 4 passes through the relay optical system 5 and then becomes, for example, a light intensity distribution based on a convolution of a circle (ring or four points) and a circle, that is, a circular shape (ring-shaped or quadrupolar). ) Light intensity distribution is formed. In other words, a circular (annular or quadrupole) secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6.

In the third embodiment, the second relay optical system 32
, Or by changing the focal length of the relay optical system 5, the overall size of the circular secondary light source can be changed. In addition, by changing the imaging magnification of the second relay optical system 32, the width of the annular secondary light source (or the size of the four light sources constituting the quadrupole secondary light source) was kept constant. The overall size of the secondary light source can be changed as it is. Further, by changing the focal length of the relay optical system 5, the whole of the annular (or quadrupole) secondary light source can be similarly enlarged or reduced.

However, when the imaging magnification of the second relay optical system 32 or the focal length of the relay optical system 5 is changed, the numerical aperture of the light beam incident on the fly-eye lens 6 (the angle θc in FIG. Changes). As a result, the exit surface of the fly-eye lens 6 is not illuminated at a sufficient ratio, and the illumination condition cannot be changed almost continuously. Therefore, in the third embodiment, the magnification of the afocal zoom lens 30 is changed to adjust the diameter of the light beam incident on the second diffractive optical element 31, and the maximum incident angle θc of the light beam incident on the fly-eye lens 6 is finally determined. By setting to a desired value, the exit surface of the fly-eye lens 6 can always be illuminated at a sufficient ratio, and the illumination condition can be changed almost continuously.

In the third embodiment, instead of the second diffractive optical element 31, for example, European Patent Publication No. 10
It is also possible to use a micro prism array disclosed in FIGS. 23 to 28 of JP-A No. 14196, a micro fly's eye lens disclosed in FIG. When a micro fly's eye lens is used instead of the second diffractive optical element 31, the cross-sectional shape of each lens element is set to a regular hexagon in order to effectively use the amount of light, and a large number of these regular hexagonal lens elements are closely packed. It is preferable to configure by filling. Further, the second diffractive optical element 31 has a very small DO.
It may be an aggregate of E-lenses, or may be one in which the phase is appropriately arranged and the diffracted light distribution has a desired distribution.

Hereinafter, more specific embodiments will be described. FIG. 11 is a view schematically showing a configuration of an exposure apparatus including an illumination optical device according to the fourth embodiment of the present invention. The fourth embodiment has a configuration similar to that of the second embodiment, except that a micro fly's eye lens (micro lens array: micro fly's eye) 40 and The point that the afocal zoom lens 41 is provided is basically different from the second embodiment. Hereinafter, the fourth embodiment will be described focusing on the differences from the second embodiment. In FIG. 11, the illumination optical device is set to perform annular illumination.

In the fourth embodiment, a substantially parallel light beam emitted from the light source 1 is incident on the micro fly's eye lens 40 for annular illumination through the beam expander 2 and the bending mirror 3. Micro fly eye lens 40
Is an optical element composed of a large number of fine hexagonal microlenses having positive refracting power arranged vertically and horizontally and densely. Generally, a micro fly's eye lens is formed by, for example, performing an etching process on a parallel flat glass plate to form a micro lens group. In FIG. 11, the number of micro lenses constituting the micro fly's eye lens 40 is shown to be much smaller than the actual number for the sake of clarity.

The light beam incident on the micro fly's eye lens 40 is two-dimensionally divided by a large number of minute lenses.
One light source is formed on the rear focal plane of each microlens. Light beams from a number of light sources formed on the rear focal plane of the micro fly's eye lens 40 become divergent light beams each having a regular hexagonal cross section and enter the afocal zoom lens 41. As described above, the micro fly's eye lens 40 constitutes an angle beam forming unit for converting the beam from the light source 1 into a beam having a plurality of angle components with respect to the optical axis AX.

The micro fly's eye lens 40 for annular illumination is configured to be insertable into and removable from the illumination optical path, and is switchable with the micro fly's eye lens 40a for quadrupole illumination. The configuration and operation of the micro fly's eye lens 40a for quadrupole illumination will be described later. The afocal zoom lens 41 is configured so that the magnification can be continuously changed within a predetermined range while maintaining an afocal system (a non-focus optical system).

Here, the micro fly's eye lens 40 for annular illumination and the micro fly's eye lens 4 for quadrupole illumination
0a, and the retreat of the micro fly's eye lenses 40 and 40a from the illumination optical path is performed by the control system 51.
This is performed by the first drive system 52 that operates based on the command from The magnification change of the afocal zoom lens 41 is performed by a second drive system 53 that operates based on a command from the control system 51.

The light beam having passed through the afocal zoom lens 41 enters the first diffractive optical element 20a for annular illumination. At this time, the divergent light beams from the respective light sources formed on the rear focal plane of the micro fly's eye lens 40 converge on the diffraction surface of the first diffractive optical element 20a while maintaining a regular hexagonal cross section. That is, the afocal zoom lens 41 optically couples the rear focal plane of the micro fly's eye lens 40 and the first diffractive optical element 20a. The numerical aperture of the light beam condensed on one point on the first diffractive optical element 20a changes depending on the magnification of the afocal zoom lens 41.

The first diffractive optical element 20 for annular illumination
“a” is configured to be freely inserted into and removed from the illumination optical path, and is configured to be switchable between the first diffractive optical element 20b for quadrupole illumination and the first diffractive optical element 20c for circular illumination. 4
The configuration and operation of the first diffractive optical element 20b for polar illumination and the first diffractive optical element 20c for circular illumination will be described later. Here, the first diffractive optical element 20a for annular illumination
The switching between the first diffractive optical element 20b for quadrupole illumination and the first diffractive optical element 20c for circular illumination is performed by the control system 5.
This is performed by the third drive system 54 that operates based on the command from the first drive system 1.

The first diffractive optical element 20a for annular illumination is
When a parallel light beam having a rectangular cross section is incident, it is a light beam conversion element for forming a ring-shaped light intensity distribution in the far field (Fraunhofer diffraction region). The light beam having passed through the first diffractive optical element 20a is incident on the second diffractive optical element 22 via the first relay optical system 21 functioning as a zoom lens. Here, the first diffractive optical element 20 a is arranged near the front focal position of the first relay optical system 21, and the second diffractive optical element 22 is arranged near the rear focal position of the first relay optical system 21. I have.
In other words, the first relay optical system 21 arranges the first diffractive optical element 20a and the second diffractive optical element 22 substantially in a Fourier transform relationship.

Therefore, as described above, when a parallel light beam having a rectangular cross section centered on the optical axis AX enters the first diffractive optical element 20a, the rear focal position of the first relay optical system 21, that is, The second diffractive optical element 22 has a ring-shaped light intensity distribution centered on the optical axis AX. However, actually, as described above, the divergent light beams from the respective light sources formed on the rear focal plane of the micro fly's eye lens 40 converge on the first diffractive optical element 20a while maintaining the regular hexagonal cross section. I do. In other words, the first
A light beam having a large number of angle components is incident on the diffractive optical element 20a, and the incident angle is defined by a light beam range of a regular hexagonal pyramid.

Accordingly, the light beam having passed through the first diffractive optical element 20a is convolved with the ring and the regular hexagon around the optical axis AX onto the second diffractive optical element 22 via the first relay optical system 21. , That is, a ring-shaped (annular) light intensity distribution centered on the optical axis AX. The size (outer diameter) of this annular light intensity distribution
Varies depending on the focal length of the first relay optical system 21. The change in the focal length of the first relay optical system 21 is as follows.
Fourth drive system 5 that operates based on a command from control system 51
5 is performed.

The second diffractive optical element 2 as a light diverging element
After being limited by an aperture stop 23 provided close to the second diffractive optical element 22, the light beam passing through the second eye 2 enters the fly-eye lens 6 via a second relay optical system 24 having a fixed focal length. I do. Here, the second diffractive optical element 22
The position of the fly-eye lens 6 and the exit surface are optically conjugate via the second relay optical system 24. In other words, the light emission portion of the second diffractive optical element 22 is configured to form an image at the exit surface position of the fly-eye lens 6 via the second relay optical system 24. Thus, an annular secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6.

The aperture stop 23 is a turret substrate (rotating plate: rotatable about a predetermined axis parallel to the optical axis AX).
(Not shown in FIG. 1). The turret substrate has a plurality of annular aperture stops having annular apertures (light transmitting portions) having different shapes (annular ratios) and sizes (outer diameters). A plurality of 4-pole aperture stops having quadrupole apertures having different diameters and a plurality of circular aperture stops having circular apertures having different sizes (outer diameters) are provided along the circumferential direction. I have. The turret substrate is configured to be rotatable around an axis parallel to the optical axis AX passing through the center point. Therefore, by rotating the turret substrate, one aperture stop selected from many aperture stops can be positioned in the illumination optical path. The rotation of the turret substrate is performed by a fifth drive system 56 that operates based on a command from the control system 51.

In FIG. 1, since a ring-shaped light intensity distribution is formed on the second diffractive optical element 22, a single annular aperture stop selected from a plurality of annular aperture stops is used as the aperture stop 23. ing. However, without being limited to the turret type aperture stop, for example, a slide type aperture stop may be adopted, or an aperture stop capable of appropriately changing the size and shape of the light transmission region may be provided in the illumination optical path. It may be fixedly attached to. Further, instead of a plurality of circular aperture stops, an iris stop capable of continuously changing the circular aperture diameter can be provided.

The light beam having passed through the fly-eye lens 6 illuminates the mask blind 8 as an illumination field stop through a condenser lens 7 in a superimposed manner. The light flux passing through the rectangular opening (light transmitting portion) of the mask blind 8 irradiates the mask M in a superimposed manner after receiving the light-condensing action of the imaging optical system 9. The light beam transmitted through the pattern of the mask M forms an image of the mask pattern on the wafer W via the projection optical system PL. A variable aperture stop for defining the numerical aperture of the projection optical system PL is provided on the entrance pupil plane of the projection optical system PL. This is done by the system 57.

In the fourth embodiment, when the magnification of the afocal zoom lens 41 changes, the center height (outside diameter (diameter)) of the annular secondary light source as a virtual image formed at the incident surface position of the fly-eye lens 6 Of the median value between the diameter and the inner diameter (diameter)
2) does not change, but only its width (１ ／ of the difference between the outer diameter and the inner diameter) changes. That is, by changing the magnification of the afocal zoom lens 41, both the size (outer diameter) of the annular secondary light source and the annular ratio (inner / outer diameter) can be changed.

When the focal length of the first relay optical system 21 changes, both the center height and its width change without changing the ring ratio of the ring-shaped secondary light source. That is, by changing the focal length of the first relay optical system 21, it is possible to change the outer diameter of the annular secondary light source without changing the annular ratio. As described above, by appropriately changing the magnification of the afocal zoom lens 41 and the focal length of the first relay optical system 21, the outer diameter and the annular ratio of the annular secondary light source can be independently changed. it can.

Next, a micro fly's eye lens 40a for quadrupole illumination is set in the illumination optical path instead of the micro fly's eye lens 40 for annular illumination, and the first diffractive optical element 20a for annular illumination is set in the illumination optical path. Instead, quadrupole illumination obtained by setting the first diffractive optical element 20b for quadrupole illumination in the illumination optical path will be described. The micro fly's eye lens 40a is composed of a large number of square shaped micro lenses having a positive refracting power arranged vertically and horizontally and densely. Therefore, the light beams from the respective light sources formed on the rear focal plane of the micro fly's eye lens 40a become divergent light beams each having a square cross section and enter the afocal zoom lens 41.

The light beam having passed through the afocal zoom lens 41 is incident on the first diffractive optical element 20b for quadrupole illumination. At this time, the divergent light beams from the respective light sources formed on the rear focal plane of the micro fly's eye lens 40a converge on the first diffractive optical element 20b while maintaining a square cross section. The first diffractive optical element 20b for quadrupole illumination has its far field (Fraunhofer diffraction region) centered on the optical axis AX in a far field (Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section centered on the optical axis AX is incident. A four-point light intensity distribution is formed. Note that a square formed by connecting these four points is a square centered on the optical axis AX.

Accordingly, the light beam having passed through the first diffractive optical element 20 b is convoluted with the four points centered on the optical axis AX and the square on the second diffractive optical element 22 via the first relay optical system 21. , That is, a quadrupolar light intensity distribution centered on the optical axis AX (consisting of four square-shaped surface light sources). Second diffractive optical element 2
The luminous flux passing through 2 forms a quadrupolar secondary light source as a virtual image at the incident surface position of the fly-eye lens 6 via the second relay optical system 24. Micro fly eye lens 40
To the micro fly's eye lens 40a and the first diffractive optical element 20a to the first diffractive optical element 20b
Switching from the annular aperture stop to the four-pole aperture stop is performed in response to the switch to the aperture stop.

The size and shape of the quadrupolar secondary light source can be defined in the same manner as the annular secondary light source.
That is, the diameter of a circle circumscribing the four surface light sources constituting the quadrupole secondary light source is defined as an outer diameter, and the diameter of a circle circumscribing the four surface light sources is defined as an inner diameter. By changing the magnification of the afocal zoom lens 41 in the same manner as in the case of the annular illumination, both the outer diameter and the annular ratio of the quadrupolar secondary light source can be changed. Further, by changing the focal length of the first relay optical system 21, the outer diameter of the quadrupole secondary light source can be changed without changing the annular ratio. As a result, the afocal zoom lens 41
By appropriately changing the magnification and the focal length of the first relay optical system 21, the outer diameter and the annular ratio of the quadrupole secondary light source can be independently changed.

Next, both the micro fly's eye lenses 40 and 40a are retracted from the illumination optical path, and the first diffractive optical element 20c for circular illumination is set in the illumination optical path instead of the first diffractive optical element 20a or 20b. The circular illumination obtained by this will be described. In this case, a substantially parallel light beam having a rectangular cross section enters the afocal zoom lens 41 along the optical axis AX. The light beam incident on the afocal zoom lens 41 is enlarged or reduced in accordance with the magnification, and the light beam having a rectangular cross section remains along the optical axis AX as the afocal zoom lens 4.
1 and is incident on the first diffractive optical element 20c.

Here, the first diffractive optical element 2 for circular illumination
0c forms a circular light intensity distribution centered on the optical axis AX in the far field (Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section centered on the optical axis AX is incident. Therefore, the light beam having passed through the first diffractive optical element 20c is transmitted to the first relay optical system 21.
A circular light intensity distribution centered on the optical axis AX is formed on the second diffractive optical element 22 through the optical path. The light beam passing through the second diffractive optical element 22 passes through the second relay optical system 24,
A circular secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6.

In accordance with the retreat of the micro fly's eye lenses 40 and 40a from the illumination optical path and the setting of the first diffractive optical element 20c for circular illumination to the illumination optical path, an annular aperture stop (or a quadrupole aperture) is required. (Aperture) to a circular aperture stop. However, in this case, since the circular light intensity distribution is formed almost exactly on the second diffractive optical element 22, the setting of the circular aperture stop on the illumination optical path can be omitted. And the afocal zoom lens 41
By appropriately changing the magnification or the focal length of the first relay optical system 21, the size (outer diameter) of the circular secondary light source can be changed.

Alternatively, circular illumination can be performed by setting the micro fly's eye lens 40a for quadrupole illumination in the illumination optical path and retracting the first diffractive optical elements 20a to 20c from the illumination optical path. Note that, in accordance with the setting of the micro fly's eye lens 40a on the illumination optical path and the retreat of the first diffractive optical elements 20a to 20c from the illumination optical path, the annular aperture stop (or quadrupole aperture stop) is changed to a circular aperture stop. Is switched. In this case, the luminous flux from each light source formed on the rear focal plane of the micro fly's eye lens 40 a passes through the afocal zoom lens 41 and the first relay optical system 21 to the second diffractive optical element 22.
A square light intensity distribution is formed thereon.

The light beam passing through the second diffractive optical element 22 is restricted via a circular aperture stop,
A circular secondary light source as a virtual image is formed at the position of the incident surface of the fly-eye lens 6 via the light source 4. Also in this case, the magnification of the afocal zoom lens 41 or the first
By appropriately changing the focal length of the relay optical system 21, the size (outer diameter) of the circular secondary light source can be changed.

Hereinafter, the switching operation of the illumination condition in the fourth embodiment will be specifically described. First, the step and repeat method or the step and
Information about various masks to be sequentially exposed according to the scanning method is input to the control system 51 via input means 50 such as a keyboard. The control system 51 stores information such as an optimum line width (resolution) and a depth of focus for various masks in an internal memory unit. 6 supplies an appropriate control signal to the drive system 57.

That is, when zonal illumination is performed under the optimum resolution and depth of focus, the first driving system 52 controls the control system 51.
The micro fly's eye lens 40 of the annular illumination is positioned in the illumination optical path based on the instruction from. Further, the third drive system 54 positions the first diffractive optical element 20a for annular illumination in the illumination optical path based on a command from the control system 51. Then, in order to obtain an annular secondary light source having a desired size (outer diameter) and annular ratio at the incident surface position of the fly-eye lens 6, the second drive system 53 is based on a command from the control system 51. The magnification of the afocal zoom lens 41 is set, and the fourth drive system 55 sets the focal length of the first relay optical system 21 based on a command from the control system 51. Further, in order to restrict the light beam from the second diffractive optical element 22 to an annular shape, the fifth drive system 56 rotates the turret based on a command from the control system 51 to move a desired annular aperture stop in the illumination optical path. Position to. In addition, the sixth drive system 57 drives the variable aperture stop of the projection optical system PL based on a command from the control system 51 as necessary.

Further, if necessary, the magnification of the afocal zoom lens 41 is changed by the second drive system 53, and the focal length of the first relay optical system 21 is changed by the fourth drive system 55. The size and annular ratio of the annular secondary light source formed at the entrance surface position of the fly-eye lens 6 can be changed as appropriate. in this case,
The turret is rotated in accordance with the change in the size of the annular secondary light source and the annular ratio, and an annular aperture stop having a desired size and annular ratio is selected and positioned in the illumination optical path. Thus, various annular illuminations can be performed by appropriately changing the size and annular ratio of the annular secondary light source.

When quadrupole illumination is performed under the optimum resolution and depth of focus, the first drive system 52 moves the micro fly's eye lens 40a for quadrupole illumination in the illumination optical path based on a command from the control system 51. Position to. Further, the third drive system 54 positions the first diffractive optical element 20b for quadrupole illumination in the illumination optical path based on a command from the control system 51. 4 having a desired size (outer diameter) and shape (ring zone ratio) at the incident surface position of the fly-eye lens 6
In order to obtain a polar secondary light source, the second drive system 53 is controlled by the afocal zoom lens 4 based on a command from the control system 51.
A magnification of 1 is set, and the fourth drive system 55 sets the focal length of the first relay optical system 21 based on a command from the control system 51. Further, in order to restrict the light beam from the second diffractive optical element 22 to a quadrupole shape, the fifth drive system 56 rotates the turret based on a command from the control system 51 to move a desired quadrupole aperture stop to the illumination optical path. Position inside. In addition, the sixth drive system 57 drives the variable aperture stop of the projection optical system PL based on a command from the control system 51 as necessary.

Further, if necessary, the magnification of the afocal zoom lens 41 is changed by the second drive system 53, and the focal length of the first relay optical system 21 is changed by the fourth drive system 55. The size and shape of the quadrupole secondary light source formed at the position of the incident surface of the fly-eye lens 6 can be appropriately changed. In this case, 4
The turret rotates according to the change in size and shape of the polar secondary light source, and a quadrupole aperture stop having a desired size and shape is selected and positioned in the illumination light path. Thus, various quadrupole illuminations can be performed by appropriately changing the size and shape of the quadrupole secondary light source.

Further, when performing ordinary circular illumination under the optimum resolution and depth of focus, the first drive system 52 retracts the micro fly's eye lenses 40 and 40a from the illumination optical path based on a command from the control system 51. Then, the third drive system 54 positions the first diffractive optical element 20c for circular illumination in the illumination optical path based on a command from the control system 51. Alternatively, the first drive system 52 positions the micro fly's eye lens 40a in the illumination optical path based on a command from the control system 51, and the third drive system 54 controls the first diffractive optical element based on the command from the control system 51. 20a to 20c are retracted from the illumination light path. Then, in order to obtain a circular secondary light source having a desired size (outer diameter) at the incident surface position of the fly-eye lens 6, the second drive system 53 uses the afocal zoom based on a command from the control system 51. The magnification of the lens 41 is set, and the fourth drive system 55 sets the focal length of the first relay optical system 21 based on a command from the control system 51. Also,
The fifth drive system 56 rotates the turret based on a command from the control system 51, and positions a desired circular aperture stop in the illumination optical path. In addition, the sixth drive system 57 drives the variable aperture stop of the projection optical system PL based on a command from the control system 51 as necessary.

Further, if necessary, the magnification of the afocal zoom lens 41 is changed by the second drive system 53, and the focal length of the first relay optical system 21 is changed by the fourth drive system 55. The size of the circular secondary light source formed at the position of the incident surface of the fly-eye lens 6 can be appropriately changed. In this case, the turret rotates according to the change in the size of the circular secondary light source, and a circular aperture stop having an opening of a desired size is selected and positioned in the illumination light path. Thus, various circular illuminations can be performed by appropriately changing the σ value. When the first diffractive optical element 20c for circular illumination is used, a circular light intensity distribution is formed almost exactly on the second diffractive optical element 22 as described above. The setting for can be omitted.

In the fourth embodiment, quadrupole illumination is performed using the micro fly's eye lens 40a formed of a square micro lens, but the micro fly's eye lens 40 formed of a regular hexagonal micro lens is used. To provide quadrupole illumination.

FIG. 12 is a view schematically showing a configuration of an exposure apparatus provided with an illumination optical device according to the fifth embodiment of the present invention. The fifth embodiment has a configuration similar to that of the fourth embodiment, except that the positional relationship between the micro fly's eye lens 40 and the first diffractive optical element 20 is opposite to that of the fourth embodiment. Hereinafter, the fifth embodiment will be described focusing on the differences from the fourth embodiment. In FIG. 12, the illumination optical device is set to perform annular illumination.

In the fifth embodiment, a substantially parallel light beam emitted from a light source 1 is transmitted through a beam expander 2 and a bending mirror 3 to a first diffractive optical element 2 for annular illumination.
0a. The first diffractive optical element 20a has a function of forming a ring-shaped light intensity distribution in the far field when a parallel light beam having a rectangular cross section is incident. The first diffractive optical element 20a is configured to be freely inserted into and removed from the illumination optical path, and the first diffractive optical element 2 for quadrupole illumination.
Switching between the first diffractive optical element 20c for 0b and the circular illumination is performed by a drive system 58 that operates based on a command from the control system 51.

The substantially parallel light beam incident on the first diffractive optical element 20a is incident on the afocal zoom lens 41, and forms a ring-shaped light intensity distribution on its pupil plane. The light from this ring-shaped light intensity distribution is emitted as a substantially parallel light beam from the afocal zoom lens 41 and enters the micro fly's eye lens 40 composed of regular hexagonal minute lenses. The afocal zoom lens 41 maintains the first diffractive optical element 20a and the entrance surface of the micro fly's eye lens 40 in an optically almost conjugate relationship, while maintaining an afocal system (afocal optical system). It is configured such that the magnification can be continuously changed within a predetermined range.

Thus, the micro fly's eye lens 40
A light beam enters from an oblique direction substantially symmetrically with respect to the optical axis AX. The light beam incident on the micro fly's eye lens 40 is two-dimensionally divided by a large number of regular hexagonal minute lenses, and one ring-shaped light source is formed on the rear focal plane of each minute lens. The micro fly's eye lens 40 is configured to be freely inserted into and removed from the illumination optical path, and the focal length of the micro lens is different from that of the micro fly's eye lens 40.
0b. Switching between the micro fly's eye lens 40 and the micro fly's eye lens 40b is performed by a drive system 59 that operates based on a command from the control system 51.

Light beams from a number of ring-shaped light sources formed on the rear focal plane of the micro fly's eye lens 40
The second diffractive optical element 22 is illuminated in a superimposed manner via the relay optical system 21. The first relay optical system 21 is a zoom lens capable of continuously changing the focal length within a predetermined range, and substantially includes a rear focal plane of the micro fly's eye lens 40 and the second diffractive optical element 22. Is related to the Fourier transform. Therefore, the second diffractive optical element 2
On 2, a light intensity distribution based on the convolution of the ring and the regular hexagon, that is, a ring-shaped light intensity distribution centered on the optical axis AX is formed.

The size (outer diameter) of this annular light intensity distribution
Varies depending on the focal length of the first relay optical system 21. The light beam having passed through the second diffractive optical element 22 is incident on the fly-eye lens 6 via the second relay optical system 24 after being restricted by the annular aperture stop 23. Thus, an annular secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6.

In the fifth embodiment, by changing the magnification of the afocal zoom lens 41, the outer diameter and the annular ratio can be changed without changing the width of the annular secondary light source. In addition, by changing the focal length of the first relay optical system 21, it is possible to change only the outer diameter of the secondary light source in the annular shape without changing the annular ratio. Therefore, the afocal zoom lens 4
By appropriately changing the magnification of 1 and the focal length of the first relay optical system 21, the outer diameter and the annular ratio of the annular secondary light source can be independently changed.

In the fifth embodiment, the half angle (diffraction angle) α of the opening angle of the light beam emitted from the first diffractive optical element 20a is set to be micro, in order to achieve both compactness and ensuring good optical performance. The angle is set to be larger than the maximum emission angle β of the light beam emitted from each light source formed by the fly-eye lens 40. Hereinafter, this point will be briefly described. First, according to a practical numerical example, the half angle (diffraction angle) α of the opening angle of the light beam emitted from the first diffractive optical element 20a is set within a range of, for example, 4 to 7 degrees.
This is because, when α is larger than, for example, 7 degrees, it becomes difficult to manufacture the first diffractive optical element 20a, and the transmittance tends to decrease.

If α is larger than, for example, 7 degrees, the diameter of the afocals zoom lens 41 increases, and the size of the apparatus increases. Further, when α becomes larger than, for example, 7 degrees, it is necessary to set the focal length of the first relay optical system 21 small in order to keep the outer diameter of the annular secondary light source at a predetermined value. The required F-number of the optical system 21 becomes too small, and it becomes difficult to manufacture the first relay optical system 21. Conversely, if α is smaller than 4 degrees, for example, it is necessary to set the focal length of the first relay optical system 21 large in order to keep the outer diameter of the annular secondary light source at a predetermined value. The overall length of the relay optical system 21 is increased, and the size of the device is increased.

On the other hand, the maximum emission angle β of the light beam emitted from each light source formed by the micro fly's eye lens 40
According to a practical numerical example, is set, for example, within the range of 1 to 3 degrees. This is because β is 3
If it becomes larger than the degree, the micro fly's eye lens 40
This is because it is necessary to set the focal length of each microlens small, so that it becomes difficult to provide a required curvature to each microlens, and it becomes difficult to manufacture the micro fly's eye lens 40.

If β is larger than 3 degrees, for example, the focal length of the first relay optical system 21 must be set small to keep the outer diameter of the annular secondary light source at a predetermined value. The required F-number of the first relay optical system 21 becomes too small, and it becomes difficult to manufacture the first relay optical system 21. Conversely, if β is smaller than 1 degree, for example, it is necessary to set the focal length of the first relay optical system 21 large in order to keep the outer diameter of the annular secondary light source at a predetermined value. The overall length of the relay optical system 21 is increased, and the size of the device is increased. Also in the quadrupole illumination and the circular illumination described later, the half angle (diffraction angle) α of the opening angle of the light beam emitted from the first diffractive optical element and the maximum emission of the light beam emitted from each light source formed by the micro fly's eye lens It is preferable to satisfy the relationship with the angle β.

The micro fly's eye lens 40
Are set such that the annular ratio of the secondary light source can be continuously changed, for example, in the range of 1/2 to 2/3. On the other hand, the focal length of each micro lens of the micro fly's eye lens 40b is set such that the annular ratio of the secondary light source can be continuously changed, for example, in the range of 2/3 to 3/4. I have. Therefore, in the state of FIG. 12 in which the micro fly's eye lens 40 is set in the illumination light path, it is possible to continuously change the annular ratio of the secondary light source over a range of, for example, 1/2 to 2/3. It is. When the micro fly's eye lens 40b is set in the illumination optical path instead of the micro fly's eye lens 40, the annular ratio of the secondary light source is continuously changed over a range of, for example, 2/3 to 3/4. Becomes possible. Thus, in the fifth embodiment, it is possible to continuously change the annular ratio of the secondary light source over a range of, for example, 1/2 to 3/4.

Next, the first diffractive optical element 20 for annular illumination
The quadrupole illumination obtained by setting the first diffractive optical element 20b for quadrupole illumination in the illumination optical path instead of a will be briefly described. In this case, the first diffractive optical element 20b
, Form a four-point light intensity distribution on the pupil plane of the afocal zoom lens 41. The light from the four-point light intensity distribution is emitted from the afocal zoom lens 41 as a substantially parallel light flux, and enters the micro fly's eye lens 40 (or 40b). Thus, one four-point light source is formed on the rear focal plane of each microlens of the micro fly's eye lens 40 (or 40b).

The micro fly's eye lens 40 (or 4
0b) Light beams from a number of four-point light sources formed on the rear focal plane are convoluted into four points and a regular hexagon on the second diffractive optical element 22 via the first relay optical system 21. , That is, a quadrupolar light intensity distribution centered on the optical axis AX (consisting of four regular hexagonal surface light sources). The light beam having passed through the second diffractive optical element 22 is restricted by the 4-pole aperture stop, and then enters the fly-eye lens 6 via the second relay optical system 24. Thus, a quadrupole secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6.

In quadrupole illumination, as in the case of annular illumination,
By changing the magnification of the afocal zoom lens 41, both the outer diameter and the annular ratio can be changed without changing the width of the quadrupole secondary light source. Further, by changing the focal length of the first relay optical system 21, it is possible to change only the outer diameter of the quadrupole secondary light source without changing the annular ratio. Therefore,
By appropriately changing the magnification of the afocal zoom lens 41 and the focal length of the first relay optical system 21, the outer diameter and the annular ratio of the quadrupole secondary light source can be independently changed.

Next, the first diffractive optical element 20a or 20
The circular illumination obtained by setting the first diffractive optical element 20c for circular illumination in the illumination optical path instead of b will be described. In this case, the substantially parallel light beam incident on the first diffractive optical element 20c forms a circular light intensity distribution on the pupil plane of the afocal zoom lens 41. Light from the circular light intensity distribution is emitted from the afocal zoom lens 41 as a substantially parallel light flux, and enters the micro fly's eye lens 40 (or 40b). Thus, one circular light source is formed on the rear focal plane of each microlens of the micro fly's eye lens 40 (or 40b).

The micro fly's eye lens 40 (or 4
0b) Light beams from a large number of circular light sources formed on the rear focal plane are formed on the second diffractive optical element 22 via the first relay optical system 21 based on the convolution of a circle and a regular hexagon. A light intensity distribution, that is, a circular light intensity distribution centered on the optical axis AX is formed. Second diffractive optical element 22
After being limited by the circular aperture stop,
The light enters the fly-eye lens 6 via the second relay optical system 24. Thus, a circular secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6. In the circular illumination, the size (outer diameter) of the circular secondary light source can be changed by appropriately changing the focal length of the first relay optical system 21.

FIG. 13 is a view schematically showing a configuration of an exposure apparatus provided with an illumination optical device according to the sixth embodiment of the present invention. The sixth embodiment has a configuration similar to that of the fourth embodiment, but is basically different from the fourth embodiment only in the configuration between the folding mirror 3 and the first relay optical system 21. Hereinafter, the sixth embodiment will be described by focusing on the differences from the fourth embodiment. In FIG. 13, the illumination optical device is set to perform annular illumination.

In the sixth embodiment, a substantially parallel light beam emitted from the light source 1 is transmitted through the beam expander 2 and the bending mirror 3 to the first diffractive optical element 6 for annular illumination.
0a. When a parallel light beam having a rectangular cross section is incident, the first diffractive optical element 60a has a light intensity distribution in an annular shape (not a ring shape but an annular shape having a predetermined width) in its far field (Fraunhofer diffraction region). Has the function of forming The first diffractive optical element 60a is configured to be freely inserted into and removed from the illumination optical path, and is configured to be switchable between the first diffractive optical element 60b for quadrupole illumination and the first diffractive optical element 60c for circular illumination. ing. Switching between the first diffractive optical elements 60a, 60b, and 60c is performed by a drive system 65 that operates based on a command from the control system 51.

The light beam passing through the first diffractive optical element 60a is
The light enters the afocal lens 61. The afocal lens 61 has a front focal position and a first diffractive optical element 60a.
Are substantially coincident with each other, and the rear focal position is substantially coincident with the position of the predetermined surface 63 indicated by the broken line in the figure. here,
The position of the predetermined surface 63 is a position where the first diffractive optical elements 20a to 20c are installed in the fourth embodiment.

Therefore, the substantially parallel light beam incident on the first diffractive optical element 60a forms an orbicular light intensity distribution on the pupil plane of the afocal lens 61, and then becomes almost parallel light beam and exits from the afocal lens 61. Is done. In the optical path between the front lens group 61a and the rear lens group 61b of the afocal lens 61, a pair of prism members 62 are provided.
a and 62b are arranged, and the detailed configuration and operation thereof will be described later. Hereinafter, in order to simplify the description, the basic configuration and operation of the sixth embodiment will be described, ignoring the operation of the pair of prism members 62a and 62b.

The light beam passing through the afocal lens 61 is
Through the first relay optical system 21, the second diffractive optical element 22
Incident on. Here, the position of the predetermined surface 63 is arranged near the front focal position of the first relay optical system 21, and the second diffractive optical element 22 is arranged near the rear focal position of the first relay optical system 21. . In other words, the first relay optical system 2
Reference numeral 1 denotes an arrangement in which the predetermined surface 63 and the second diffractive optical element 22 are substantially arranged in a Fourier transform relationship, and thus the pupil plane of the afocal lens 61 and the second diffractive optical element 22 are optically substantially conjugated. are doing.

Therefore, on the second diffractive optical element 22, as in the pupil plane of the afocal lens 61, the optical axis AX
And a ring-shaped light intensity distribution centered at. The size (outer diameter) of this annular light intensity distribution changes depending on the focal length of the first relay optical system 21. The light beam having passed through the second diffractive optical element 22 is incident on the fly-eye lens 6 via the second relay optical system 24 after being restricted by the annular aperture stop 23. Thus, an annular secondary light source as a virtual image is formed at the incident surface position of the fly-eye lens 6.

In the sixth embodiment, as described above, a pair of prism members 62a is provided in the optical path between the front lens group 61a and the rear lens group 61b of the afocal lens 61.
And 62b are disposed. The conical axicon 62 includes, in order from the light source side, a first prism member 62a having a flat surface facing the light source side and a concave conical refraction surface facing the mask side, and a convex conical shape facing the mask side and facing the light source side. Second prism member 62 with a refracting surface facing
b. Then, the first prism member 6
The concave conical refraction surface 2a and the convex conical refraction surface of the second prism member 62b are formed complementarily so as to be able to abut each other.

The first prism member 62a and the second prism member 62a
At least one of the prism members 62b is configured to be movable along the optical axis AX.
The distance between the concave conical refracting surface 2a and the convex conical refracting surface of the second prism member 62b is configured to be variable. The change in the interval between the conical axicons 62 is performed by a drive system 66 that operates based on a command from the control system 51. In addition,
In FIG. 13, a first prism member 62a having a concave conical refracting surface and a second prism member 62b having a convex conical refracting surface are arranged in this order from the light source side, but the arrangement order is reversed. You can also.

Here, when the concave conical refracting surface of the first prism member 62a and the convex conical refracting surface of the second prism member 62b are in contact with each other, the conical axicon 62 functions as a parallel plane plate, There is no effect on the formed annular secondary light source. However, when the concave conical refracting surface of the first prism member 62a and the convex conical refracting surface of the second prism member 62b are separated, the conical axicon 62
Functions as a so-called beam expander. Therefore, with the change of the interval of the conical axicon 62,
The angle of the light beam incident on the predetermined surface 63 changes. That is,
The conical axicon 62 constitutes an incident angle changing element for changing the incident angle of the incident light beam on the predetermined surface 63.

As a result, the outer and inner diameters of the annular secondary light source formed as a virtual image at the incident surface position of the fly-eye lens 6 change without changing. Thus, in the sixth embodiment, by changing the interval between the conical axicons 62, it is possible to change the outer diameter and the zone ratio without changing the width of the annular secondary light source. In addition, by changing the focal length of the first relay optical system 21, it is possible to change only the outer diameter of the secondary light source in the annular shape without changing the annular ratio. Therefore, the interval between the conical axicon 62 and the first relay optical system 2
By appropriately changing the focal length of 1, the outer diameter and the annular ratio of the annular secondary light source can be independently changed.

Next, the first diffractive optical element 60 for annular illumination is used.
The quadrupole illumination obtained by setting the first diffractive optical element 60b for quadrupole illumination in the illumination optical path instead of a will be briefly described. In this case, the first diffractive optical element 60b
After forming a quadrupolar light intensity distribution on the pupil plane of the afocal lens 61, the substantially parallel light beam incident on the afocal lens 61 is emitted from the afocal lens 61 as a substantially parallel light beam. The light beam having passed through the afocal lens 61 forms a quadrupole light intensity distribution about the optical axis AX on the second diffractive optical element 22 via the first relay optical system 21. The light beam passing through the second diffractive optical element 22 is restricted by a quadrupole aperture stop, and then passes through a second relay optical system 24 to a quadrupolar secondary as a virtual image at the incident surface position of the fly-eye lens 6. Form a light source.

Thus, in the quadrupole illumination of the sixth embodiment,
By changing the interval of the conical axicon 62, 4
The outer diameter and annular ratio can be changed without changing the width of the polar secondary light source. Further, by changing the focal length of the first relay optical system 21, it is possible to change only the outer diameter of the quadrupole secondary light source without changing the annular ratio. Therefore, the conical axicon 6
By appropriately changing the interval of 2 and the focal length of the first relay optical system 21, the outer diameter and the annular ratio of the quadrupole secondary light source can be independently changed.

Further, the first diffractive optical element 6 for annular illumination
The circular illumination obtained by setting the first diffractive optical element 60c for circular illumination in the illumination optical path instead of the first diffractive optical element 60b for 0a or quadrupole illumination will be briefly described. In this case, the substantially parallel light beam incident on the first diffractive optical element 60c forms a circular light intensity distribution on the pupil plane of the afocal lens 61, and then emerges from the afocal lens 61 as a substantially parallel light beam. .

The light beam passing through the afocal lens 61 is
Through the first relay optical system 21, the second diffractive optical element 22
Then, a circular light intensity distribution centered on the optical axis AX is formed. The light beam passing through the second diffractive optical element 22 is restricted by a circular aperture stop, and then, through a second relay optical system 24, a circular secondary light source as a virtual image is provided at the incident surface position of the fly-eye lens 6. Form. In the circular illumination, the size (outer diameter) of the circular secondary light source can be changed by changing the focal length of the first relay optical system 21.

FIG. 14 is a diagram schematically showing the configuration of an exposure apparatus provided with an illumination optical device according to the seventh embodiment of the present invention. The seventh embodiment has a configuration similar to that of the sixth embodiment, but is basically different from the sixth embodiment only in that a pair of V-groove axicons are set in place of the conical axicon. Hereinafter, the seventh embodiment will be described by focusing on the differences from the sixth embodiment. In FIG. 14, the illumination optical device is set to perform annular illumination.

In the seventh embodiment, a substantially parallel light beam emitted from the light source 1 passes through the beam expander 2, the bending mirror 3, and the first diffractive optical element 60a for annular illumination, and the pupil of the afocal lens 61. After forming an annular light intensity distribution on the surface, the light is emitted from the afocal lens 61 as a substantially parallel light flux. In the optical path between the front lens group 61a and the rear lens group 61b of the afocal lens 61, a pair of prism members 71a and 71
b, and a second V-groove axicon 7 composed of a pair of prism members 72a and 72b.
2, and its detailed configuration and operation will be described later.

The light beam passing through the afocal lens 61 is
Through the first relay optical system 21, the second diffractive optical element 22
Then, an annular light intensity distribution centered on the optical axis AX is formed. The luminous flux passing through the second diffractive optical element 22 is restricted by the annular aperture stop 23, and then, through the second relay optical system 24, at the position of the incident surface of the fly-eye lens 6, the annular image as a virtual image is formed. The next light source is formed. Note that, similarly to the sixth embodiment, when the focal length of the first relay optical system 21 changes, only the outer diameter of the secondary light source in a ring shape changes without changing the ring ratio.

FIG. 15 is a diagram schematically showing the configuration of the first V-groove axicon and the second V-groove axicon arranged in the optical path of the afocal lens. 14 and 15
As shown in the figure, in the optical path of the afocal lens 61,
A first V-groove axicon 71 and a second V-groove axicon 72 are arranged in this order from the light source side. The first V-groove axicon 71 has a first prism member 71a having a flat surface facing the light source and a concave refraction surface facing the mask, and a first prism member 71a having a flat refraction surface facing the mask side and the light source side. And two prism members 71b. The concave refraction surface of the first prism member 71a is composed of two planes, and the line of intersection extends along the X direction.

The convex refracting surface of the second prism member 71b is
It is formed complementary to the concave refraction surface of the first prism member 71a, in other words, so as to be able to contact the concave refraction surface of the first prism member 71a. That is, the convex refraction surface of the second prism member 71b is also composed of two planes,
The intersection line extends along the X direction. Further, at least one of the first prism member 71a and the second prism member 71b is configured to be movable along the optical axis AX,
The distance between the concave refraction surface of the first prism member 71a and the convex refraction surface of the second prism member 71b is configured to be variable. The change in the interval between the first V-groove axicons 71 is performed by a drive system 75 that operates based on a command from the control system 51.

On the other hand, the second V-groove axicon 72 is a first V-groove axicon 72 having a flat surface facing the light source and a concave refraction surface facing the mask side.
It is composed of a prism member 72a and a second prism member 72b with a flat surface facing the mask side and a convex refracting surface facing the light source side. The concave refraction surface of the first prism member 72a is composed of two planes, and the line of intersection extends along the Z direction. The convex refraction surface of the second prism member 72b is formed complementary to the concave refraction surface of the first prism member 72a. That is, the convex refraction surface of the second prism member 72b is also composed of two planes, and the line of intersection extends along the Z direction. Further, at least one of the first prism member 72a and the second prism member 72b is configured to be movable along the optical axis AX, and the concave refraction surface of the first prism member 72a and the convex refraction surface of the second prism member 72b. Is configured to be variable. The change in the interval between the second V-groove axicons 72 is performed by a drive system 76 that operates based on a command from the control system 51.

Here, when the opposing concave refraction surface and convex refraction surface are in contact with each other, the first V-groove axicon 71 and the second V-groove axicon 72 function as parallel plane plates, and the formed annular zone is formed. Has no effect on the secondary light source. However, when the concave refraction surface and the convex refraction surface are separated from each other, the first V-groove axicon 71 functions as a parallel plane plate along the X direction, but functions as a beam expander along the Z direction. Further, the second V-groove axicon 72, when the concave refraction surface and the convex refraction surface are separated from each other,
It functions as a plane parallel plate along the direction, but functions as a beam expander along the X direction. That is,
First V-groove axicon 71 and second V-groove axicon 72
Constitutes an aspect ratio changing element that changes the aspect ratio of the incident light beam in order to change the incident angle of the incident light beam on the predetermined surface 63 along the predetermined direction.

Accordingly, although the angle of incidence of the light beam incident on the predetermined surface 63 along the X direction does not change with the change in the distance between the first V-groove axicons 71, the angle of the light beam incident on the predetermined surface 63 along the Z direction does not change. The incident angle changes. As a result, as shown in FIG. 16A, the four quarter-arc surface light sources 81 to 84 constituting the annular secondary light source do not move in the X direction but move in the Z direction. That is, when the distance between the first V-groove axicons 71 increases, the surface light sources 81 and 8
2 moves in the + Z direction, and the surface light sources 83 and 84 move in the -Z direction.

On the other hand, with the change in the distance between the second V-groove axicons 72, the angle of incidence of the light beam incident on the predetermined surface 63 along the Z direction does not change.
The angle of incidence along the direction changes. As a result, FIG.
As shown in (b), the surface light sources 81 to 84 do not move in the Z direction but move in the X direction. That is, when the interval between the second V-groove axicons 72 increases, the surface light sources 81 and 83 move in the −X direction, and the surface light sources 82 and 84 move to the + X direction.
Move in the direction.

Further, when the interval between the first V-groove axicon 71 and the interval between the second V-groove axicon 72 both change, the incident angle of the light beam incident on the predetermined surface 63 along the X direction and the incident angle along the Z direction are both changed. Change. As a result, as shown in FIG.
Moves in the Z and X directions. That is, the first V
Spacing of groove axicon 71 and second V-groove axicon 72
Are increased, the surface light source 81 moves in the + Z direction and the −X direction, and the surface light source 82 moves in the + Z direction and the + X direction.
The surface light source 83 moves in the −Z direction and the −X direction, and the surface light source 84 moves in the −Z direction and the + X direction. Thus, a quadrupole secondary light source including four independent arc-shaped surface light sources can be formed.

As in the case of the sixth embodiment, by setting the first diffractive optical element 60b for quadrupole illumination in the illumination optical path instead of the first diffractive optical element 60a for annular illumination, the annular illumination is achieved. It can be performed. In this case, when the distance between the first V-groove axicons 71 increases, as shown in FIG. 17A, four surface light sources 85 to 85 constituting a quadrupole secondary light source are formed.
Of the 88, the surface light sources 85 and 86 move in the + Z direction, and the surface light sources 87 and 88 move in the -Z direction.

On the other hand, when the distance between the second V-groove axicons 72 increases, the surface light sources 85 and 87 move in the −X direction, and the surface light sources 86 and 88 move + as shown in FIG.
Move in X direction. Further, when the distance between the first V-groove axicon 71 and the distance between the second V-groove axicons 72 both increase, as shown in FIG.
The surface light source 86 moves in the + Z direction and the + X direction, and the surface light source 87 moves in the −Z direction and the −X direction.
Moving in the X direction, the surface light source 88 moves in the −Z direction and the + X direction.

Further, similarly to the sixth embodiment, a first diffractive optical element 60c for circular illumination is replaced by a first diffractive optical element 60c for circular illumination instead of the first diffractive optical element 60a for annular illumination or the first diffractive optical element 60b for quadrupole illumination. Circular illumination can be performed by setting in the illumination optical path. In this case, the first V-groove axicon 7
When the interval of 1 is increased, as shown in FIG. 18A, four quarter-circular surface light sources 89 constituting a circular secondary light source
a to 89d, the surface light sources 89a and 89b have + Z
, And the surface light sources 89c and 89d move in the −Z direction.

On the other hand, when the distance between the second V-groove axicons 72 increases, the surface light sources 89a and 89c move in the -X direction as shown in FIG.
9d moves in the + X direction. Further, when the distance between the first V-groove axicon 71 and the distance between the second V-groove axicon 72 both increase, as shown in FIG.
9a moves in the + Z direction and the -X direction, and the surface light source 89b
Moves in the + Z direction and the + X direction, and the surface light source 89 c
The surface light source 89d moves in the Z direction and the −X direction, and moves in the −Z direction and the + X direction. In this way, a quadrupole secondary light source composed of four independent quadrangular surface light sources can be formed.

In the seventh embodiment, a first V-groove axicon 71 functioning as a beam expander along the Z direction and a second V-groove axicon 72 functioning as a beam expander along the X direction are arranged in order from the light source side. Although they are arranged, the arrangement order can be reversed. In the first V-groove axicon 71 and the second V-groove axicon 72, a first prism member having a concave conical refracting surface and a second prism having a convex conical refracting surface are arranged in this order from the light source side. However, the arrangement order can be reversed.

In the seventh embodiment, each of the first V-groove axicon 71 and the second V-groove axicon 72 is composed of a pair of prism members. However, the present invention is not limited to this, and as shown in FIG. The second prism member 71b of the first V-groove axicon 71 and the second V-groove axicon 7
A prism member 73 in which the second first prism member 72a is integrated can also be used. In this case, at least two of the first prism member 71a of the first V-groove axicon 71, the integrated prism member 73, and the second prism member 72b of the second V-groove axicon 72 are connected to the optical axis AX.
Along the first V-groove axicon 7
1 and the distance between the second V-groove axicons 72 can be independently changed.

Further, in the seventh embodiment, a pair of V-groove axicons 71 and 72 are arranged in the optical path of the afocal lens 61.
The conical axicon 62 according to the sixth embodiment may be provided in the optical path between the second lens unit 61 and the rear lens group 61b of the afocal lens 61. Thus, also in the seventh embodiment, similarly to the sixth embodiment, by appropriately changing the interval between the conical axicons 62 and the focal length of the first relay optical system 21, a secondary light source having an annular or quadrupolar shape is obtained. The outer diameter and the annular ratio can be independently changed.

In this case, the second V-groove axicon 71
A prism member 73 obtained by integrating the prism member 71b and the first prism member 72a of the second V-groove axicon 72 is used, and the second prism member 72b of the second V-groove axicon 72 and the first prism member 62a of the conical axicon 62 Can be used as the prism member 74 (not shown). Then, the first V-groove axicon 71
A first prism member 71a, an integrated prism member 73,
Integrated prism member 74 and conical axicon 6
By moving at least three members of the second second prism members 62b along the optical axis AX, the distance between the first V-groove axicon 71, the distance between the second V-groove axicons 72, and the distance between the conical axicons 62 are independently set. Can be changed.

In the sixth and seventh embodiments, the afocal lens 61 and the first relay optical system 21 are used.
Although the optical member is not arranged in the optical path between them, a modified example in which the micro fly's eye lens is arranged at the position of the predetermined surface 63 is also possible. In this modified example, the rear focal position of the afocal lens 61 and the incident surface of the micro fly's eye lens substantially coincide, and the front focal position of the first relay optical system 21 substantially coincides with the exit surface of the micro fly's eye lens. Is set to As the first diffractive optical element for annular illumination (for quadrupole illumination), a diffractive optical element that forms a ring-like (four-point) light intensity distribution in the far field is used.

Here, when the cross-sectional shape of each micro lens constituting the micro fly's eye lens is a regular hexagon, the second diffractive optical element 22 applies light based on a convolution of a ring (four points) and a regular hexagon. An intensity distribution, that is, an annular (quadrupole) light intensity distribution centered on the optical axis AX is formed. The light beam passing through the second diffractive optical element 22 is restricted by the annular aperture stop 23 (quadruple aperture stop),
Through the second relay optical system 24, an annular (quadrupole) secondary light source as a virtual image is formed at the entrance surface position of the fly-eye lens 6. In this modification, the afocal zoom lens 41 according to the fourth and fifth embodiments can be used instead of the afocal lens 61.

Next, adjustment operations for optimizing the illumination characteristics of the illumination optical device of each embodiment will be described. Here, as the illumination characteristics of the illumination optical device,
Variations in the illuminance distribution of the exposure light in the illumination area on the mask M (and, consequently, the exposure area on the wafer W) (hereinafter, referred to as “illuminance unevenness”), and the amount of collapse of the telecentricity of the exposure light on the mask M (hereinafter, “ Lighting telecentric ”). This is because these two illumination characteristics have the greatest influence on the image projected by the projection optical system PL and the photoresist on the wafer W.

The illuminance unevenness is defined as a primary component (referred to as an “inclination component”) relating to the position of the exposure area in the non-scanning direction (a direction perpendicular to the scanning direction), and a second component relating to the position.
It is divided into a next component (this is called an “irregular component”). Here, the illuminance unevenness component in the scanning direction is not particularly adjusted because it is averaged by the scanning exposure. The unevenness component of uneven illuminance is a component that is symmetric with respect to the optical axis (axially symmetric component)
It is. In addition, the illumination telecentric is used for the illumination area (exposure area).
A tilt component (shift component) corresponding to an average tilt angle of the exposure light in the X direction and the Y direction, and a magnification corresponding to an average tilt angle of the exposure light in the radial direction with respect to the optical axis of the exposure light. Separate into ingredients.

First, in order to measure uneven illuminance, a glass substrate on which no pattern is formed is set in place of the mask M. Then, the exposure area is irradiated with exposure light,
The light receiving unit of the uneven illuminance sensor scans in a non-scanning direction on a surface corresponding to the exposure area of the wafer W, and captures a detection signal of the uneven illuminance sensor. Instead of a glass substrate on which no pattern is formed, a region of the mask M where a pattern is not formed, or a region of an evaluation mark plate described later where an evaluation mark is not formed may be used. Thus, based on the obtained detection signal curve, the inclination component and the unevenness component of the illuminance unevenness can be obtained.

On the other hand, in order to measure the illumination telecentricity, an evaluation mark plate is installed at the position of the mask M, and a scanning plate of the aerial image measurement system is installed near a surface corresponding to the exposure area of the wafer W. Then, the focus position of the scanning plate is set to the projection optical system P.
The image plane (best focus position) with respect to L is set higher by + δ (δ is preset within a range in which a predetermined resolution can be obtained), irradiation of exposure light is started, and an evaluation mark on an evaluation mark plate is set. Is projected on the wafer stage. In this state, the image of the evaluation mark is scanned in the X direction and the Y direction by the opening pattern of the scanning plate, and the obtained detection signals are processed, thereby calculating the positions of the images in the X direction and the Y direction. .

Next, the focus position of the scanning plate is set lower than the best focus position by -δ, and the positions of the evaluation mark image in the X direction and the Y direction are similarly obtained using the aerial image measurement system. In this way, the tilt component of the illumination telecentric can be obtained from the average shift amount of the image of the evaluation mark with respect to the change amount of the focus position of the scanning plate. Further, the magnification component of the illumination telecentric can be obtained from the average shift amount of the evaluation mark image in the radial direction.

In each of the above embodiments, when switching the illumination conditions, the illuminance unevenness and the illumination telecentricity are measured as necessary. Here, the switching of the illumination condition means switching between annular illumination, quadrupole illumination, and circular illumination, and the size (outer diameter) or shape (annular zone ratio) of the secondary light source in annular illumination or quadrupole illumination. ), The size (outer diameter) of the secondary light source in the circular illumination, and the like. By measuring the illuminance unevenness, a slope component (a primary component) of the illuminance unevenness and a concavo-convex component (a secondary component) of the illuminance unevenness are calculated. In addition, by measuring the illumination telecentric, a tilt component (shift component) of the illumination telecentric and a magnification component of the illumination telecentric are calculated.

Next, it is determined whether or not each of the calculated illuminance unevenness and the illumination telecentric component is within an allowable range. If any of the components is out of the allowable range, an adjusting operation is performed. Specifically, when the tilt component of the illuminance unevenness exceeds the allowable range, some of the lenses or the lens groups constituting the condenser lens 7 are tilted (tilted) with respect to the optical axis AX. Adjusts the tilt component of uneven illuminance. If the unevenness component of the illuminance unevenness exceeds the allowable range, a density filter plate (predetermined transmittance distribution) arranged near the conjugate plane of the mask M in the optical path between the condenser lens 7 and the mask blind 8 Is rotated around the optical axis AX to adjust the unevenness component of the uneven illuminance.

Further, when the tilt component of the illumination telecentric lens is outside the allowable range, some of the lenses or lens groups constituting the condenser lens 7 are two-dimensionally moved along a plane perpendicular to the optical axis AX. By shifting (moving) the object, the tilt component of the illumination telecentric is adjusted. When the magnification component of the illumination telecentric is outside the allowable range, a method of adjusting the magnification component of the illumination telecentric by moving the fly-eye lens 6 along the optical axis AX can be considered in light of the related art.

However, in each of the above embodiments, unlike the prior art in which the secondary light source is formed at the rear focal position of the fly-eye lens 6, the secondary light source as a virtual image is located at the incident surface position of the fly-eye lens 6. Is formed. As a result, even if only the fly-eye lens 6 is moved along the optical axis AX, the magnification component of the illumination telecentric cannot be adjusted. Therefore, in the second to seventh embodiments, the magnification component of the illumination telecentric is adjusted by moving the second diffractive optical element 22 and the fly-eye lens 6 along the optical axis AX. In the first embodiment, the diffractive optical element 4
By moving both the fly-eye lens 6 and the fly-eye lens 6 along the optical axis AX, the magnification component of the illumination telecentric is adjusted.

More specifically, when the second relay optical system 24 (relay optical system 5) has the same magnification, the second diffractive optical element 22 (diffractive optical element 4) and the fly-eye lens 6 are integrated. To adjust the magnification component of the illumination telecentric. When the second relay optical system 24 (relay optical system 5) is not the same magnification, the second relay optical system 24
The magnification component of the illumination telecentric is adjusted by moving the second diffractive optical element 22 (diffractive optical element 4) and the fly-eye lens 6 by a predetermined amount in accordance with the magnification of the (relay optical system 5).

After that, the illuminance unevenness and the illumination telecentricity are re-measured, and it is determined whether or not each of the measured illuminance unevenness and the illumination telecentric component is within the allowable range. If any component is out of the allowable range, the above-described adjustment operation is repeated. On the other hand, when all components fall within the allowable range, the adjustment operation ends. By automating the above-described measurement operation and adjustment operation, when the same illumination condition is set next, the measurement and adjustment of the illumination characteristics are completed in a very short time based on the stored adjustment data. can do.

In each of the above embodiments, for example, a micro fly's eye lens can be used instead of the second diffractive optical element 22 (or the diffractive optical element 4). In this case, when the number of wavefront divisions is increased by setting the size of each microlens element constituting the micro fly's eye lens to be small, the spatial coherency of two lights passing through two adjacent microlens elements becomes high. As a result, speckle interference fringes occur on the mask M and the wafer W, and the uniformity of the illuminance distribution deteriorates. Therefore, in each of the above-described embodiments, by forming a micro fly's eye lens with two types of minute lens elements having different optical thicknesses along the optical axis AX, the illuminance distribution caused by the speckle-like interference fringes can be made uniform. The deterioration of the property can be suppressed well.

FIG. 20 is a diagram showing a main configuration of a micro fly's eye lens composed of two types of micro lens elements having different optical thicknesses along the optical axis AX. Specifically, in the micro fly's eye lens 90 used in place of the second diffractive optical element 22 (or the diffractive optical element 4),
There are two types such that the phase difference between the light passing through the small lens element 90a having a small optical thickness and the light passing through the small lens element 90b having a large optical thickness is 180 degrees in the fly-eye lens 6. Micro lens elements 90a and 90
The difference in the optical thickness of b can be set.

For example, an ArF excimer laser light source is used as the light source 1 and the same optical material (quartz or fluorite) is used for each microlens element constituting the micro fly's eye lens 90.
Is used, the difference between the thicknesses of the two types of microlens elements is set to about 0.2 μm or an odd multiple thereof (3 ×, 5 ×,...). In some cases, by using optical materials having different refractive indices (single optical material or composite optical material) for the two types of micro lens elements constituting the micro fly's eye lens 90, the thickness of each micro lens element can be increased. Even if the thickness is set to be constant, a desired optical thickness difference can be secured between the two types of microlens elements.

FIG. 21 is a view showing an example of the arrangement of two types of micro lens elements constituting the micro fly's eye lens of FIG. In FIG. 21, a hatched portion indicates a microlens element 90a having a small optical thickness, and a blank portion indicates a microlens element 90b having a large optical thickness. FIG.
In the arrangement example of (a), the microlens elements having the same optical thickness are mutually aligned along four directions of each horizontal direction, each vertical direction, and each diagonal direction (right-up diagonal direction and left-up diagonal direction). The number of adjacent combinations and the number of adjacent microlens elements having different optical thicknesses are the same.

Here, light passing through two adjacent microlens elements having the same optical thickness forms speckle-shaped interference fringes on the mask M and the wafer W which are surfaces to be irradiated. On the other hand, light passing through two adjacent microlens elements having different optical thicknesses also has an optical path length difference substantially shorter than the temporal coherence distance (for example, 1/1 of the temporal coherence distance).
Since only 0 or less optical path length difference is provided, speckle interference fringes are formed on the mask M and the wafer W. However, light passing through two adjacent microlens elements having the same optical thickness, that is, speckle interference fringes formed by light having the same phase, and light passing through two adjacent microlens elements having different optical thicknesses. The phase is shifted from light, that is, speckle interference fringes formed by light having the opposite phase.

As a result, two speckle-like interference fringes having different phases overlap each other and cancel each other, so that the contrast of the combined interference fringe is reduced. In particular, FIG.
According to the arrangement example shown in (a), as described above, a combination in which minute lens elements having the same optical thickness are adjacent to each other and a combination in which minute lens elements having different optical thicknesses are adjacent to each other are 4 The number is the same along the direction. Therefore, it is possible to effectively suppress the deterioration of the uniformity of the illuminance distribution caused by the speckle-like interference fringes by making the most of the canceling action of the two speckle-like interference fringes having different phases.

On the other hand, in the arrangement example of FIG. 21B, a combination in which minute lens elements having the same optical thickness are adjacent to each other and a combination in which minute lens elements having different optical thicknesses are adjacent to each other are in four directions. Although the number is not the same along any of the directions, it is fairly uniform along each direction as a whole. Therefore, in the case of the arrangement example of FIG. 21B, similarly to the case of the arrangement example of FIG. 21A, the speckle interference is performed by using the canceling action of two speckle interference fringes having different phases from each other. Deterioration of the uniformity of the illuminance distribution caused by the stripes can be suppressed well.

In the case of the arrangement example of FIG. 21B, the entire arrangement pattern is very regular and simple, and the manufacture of the micro fly's eye lens 90 is easy. In addition,
Although illustration is omitted, two types of microlens elements having different optical thicknesses are arranged at random, so that FIG.
As in the case of the arrangement example of FIG. 21A and the arrangement example of FIG. 21B, the illuminance distribution caused by the speckle interference fringes is utilized by using the canceling action of two speckle interference fringes having different phases from each other. Can be favorably suppressed from being deteriorated.

In the above description, one micro fly's eye lens 90 is used in place of the second diffractive optical element 22 (or the diffractive optical element 4), but a pair of micro fly's eye lenses 90 are spaced apart along the optical axis AX. Micro fly's eye lens can also be used. In this case, only the micro fly's eye lens on the light source side may constitute the phase difference imparting means, only the micro fly's eye lens on the mask side may constitute the phase difference imparting means, or both micro fly's eye lenses may constitute the phase difference imparting means. The phase difference providing means may be constituted by the cooperation of the lenses.

In the above description, the micro fly's eye lens constitutes the phase difference providing means. However, a cover glass is arranged on the light source side or the mask side, and the cover glass and the mask side arranged on the light source side are arranged. , Or both cover glasses may constitute the phase difference imparting means. For example, when the phase difference providing means is constituted by one cover glass disposed on the light source side or the mask side, the cover glass includes a first group of minute regions through which the first group of light beams pass, and a second group of the second group. The second through which the light beam passes
The first group of minute regions and the second group of minute regions have different optical thicknesses along the optical axis. In other words, the cover glass is formed as a so-called phase plate. According to this aspect, the phase difference providing means can be configured by another phase plate arranged in the illumination optical path.

Further, in the above description, the micro fly's eye lens is composed of two types of micro lens elements having different optical thicknesses. However, the number of types of micro lens elements constituting the micro fly's eye lens is 3 More than one can be set. Therefore, also in the phase plate, three or more types of minute regions having different optical thicknesses can be formed. In this case, the multiple light sources formed by the micro fly's eye lens have a first to third light source groups,
The same amount between the first group and the second group, between the first group and the third group, and between the third group and the second group. The micro fly's eye lens has three types of micro lenses having different optical thicknesses so as to provide only a phase difference (a phase difference of 120 degrees), and the phase plate has three types of micro lenses having different optical thicknesses. It is desirable to have a configuration having a region. At this time, the maximum value of the optical path length difference in the entire micro fly's eye lens given by the difference in optical thickness of the three types of microlenses is 1/10 or less of the temporal coherence length of the light beam. It is even more preferred. Similarly, the maximum value of the optical path length difference of the entire phase plate, which is given by the fact that the optical thicknesses of the three types of micro regions are different in the phase plate, is 1/1 / the temporal coherence length of the light beam. More preferably, it is 10 or less.

In the above description, the micro fly's eye lens is constituted by two kinds of minute lens elements having different optical thicknesses. However, the two kinds of minute lens elements have different focal lengths. Can also be set. In this case, the light passing through the microlens element having a relatively long focal length and the light passing through the microlens element having a relatively short focal length require the size of the illumination area formed on the mask M that is the irradiation surface. Will be different. As a result, it is possible to control the illuminance distribution around the illumination area via a plurality of types of microlens elements having different focal lengths.

Further, in the above description, the micro fly's eye lens is constituted by two kinds of minute lens elements having different optical thicknesses, but the two kinds of minute lens elements have incident surfaces of different sizes from each other. It can be set as follows. In this case, since the entrance surface of the micro lens element constituting the micro fly's eye lens is arranged optically conjugate with the irradiated surface, light passing through the micro lens element having a relatively large entrance surface and light of the entrance surface The size of the illumination area formed on the mask M, which is the surface to be illuminated, differs from the light passing through the relatively small microlens element. As a result, it is possible to control the illuminance distribution around the illumination area via a plurality of types of microlens elements having incident surfaces of different sizes.

In the above description, a micro fly's eye lens is used instead of the second diffractive optical element 22 (or the diffractive optical element 4). However, the same applies to the case where a Fresnel lens type diffractive optical element is used. In some cases, the uniformity of the illuminance distribution may be deteriorated due to the speckle interference fringes.
In this case, the Fresnel lens type diffractive optical element itself may constitute the phase difference providing means, or a cover glass may be disposed on the light source side or the mask side, and the cover glass disposed on the light source side and disposed on the mask side. The phase difference providing means may be constituted by the cover glass or both cover glasses.

In the exposure apparatus according to each of the above embodiments,
A mask (reticle) is illuminated by an illumination optical device (illumination step), and a transfer pattern formed on the mask is exposed on a photosensitive substrate using a projection optical system (exposure step), thereby forming a micro device (semiconductor element). , An imaging element, a liquid crystal display element, a thin-film magnetic head, etc.). Hereinafter, an example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of each embodiment will be described with reference to the flowchart in FIG. Will be explained.

First, in step 301 of FIG.
A metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the l lot of wafers. Then, step 30
In 3, using the exposure apparatus of each embodiment, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of the lot through the projection optical system.
Thereafter, in Step 304, after the photoresist on the wafer of the lot is developed, Step 3
At 05, a circuit pattern corresponding to the pattern on the mask is formed in each shot region on each wafer by performing etching on the wafer of the lot using the resist pattern as a mask. Thereafter, a device such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer and the like. According to the above-described semiconductor device manufacturing method, a semiconductor device having an extremely fine circuit pattern can be obtained with good throughput.

In the exposure apparatus of each embodiment, a predetermined pattern (circuit pattern,
By forming an electrode pattern or the like, a liquid crystal display element as a microdevice can be obtained. Hereinafter, an example of the technique at this time will be described with reference to the flowchart in FIG. In FIG. 23, in a pattern forming step 401, a so-called photolithography step of transferring and exposing a pattern of a mask onto a photosensitive substrate (a glass substrate coated with a resist or the like) using the exposure apparatus of each embodiment is executed. By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate is subjected to various steps such as a developing step, an etching step, and a reticle peeling step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step 402.

Next, in the color filter forming step 402, three colors corresponding to R (Red), G (Green), and B (Blue)
Many sets of dots are arranged in a matrix,
Alternatively, a color filter in which a plurality of sets of three stripe filters of R, G, and B are arranged in the horizontal scanning line direction is formed. Then, after the color filter forming step 402, a cell assembling step 403 is performed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like. In the cell assembling step 403, for example, a liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern forming step 401 and the color filter obtained in the color filter forming step 402, and a liquid crystal panel (liquid crystal cell) is formed. ) To manufacture.

Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display device, a liquid crystal display device having an extremely fine circuit pattern can be obtained with high throughput.

In each of the embodiments described above, the fly-eye lens 6 is formed by integrating a large number of lens elements. However, a micro fly-eye lens can be used instead of the fly-eye lens 6. . The micro fly's eye lens has a plurality of minute lens surfaces provided in a matrix on a light transmitting substrate by a method such as etching. Although there is substantially no functional difference between the fly-eye lens and the micro fly-eye lens in forming a plurality of light source images, the size of the aperture of one element lens (micro lens) is extremely small. The micro fly's eye lens is advantageous in that it can be manufactured, the manufacturing cost can be greatly reduced, and the thickness in the optical axis direction can be extremely reduced.

In each of the above embodiments, the present invention has been described by taking the projection exposure apparatus having the illumination optical device as an example. However, the present invention is applied to a general illumination optical apparatus for illuminating a surface to be illuminated other than a mask. It is clear that the invention can be applied. Incidentally, a detailed description of the diffractive optical element that can be used in the present invention can be found in US Pat.
No. 0,300 and the like. In each of the above embodiments, since the incident surface of the fly-eye lens 6 is optically substantially conjugate to the surface to be irradiated, the optical member whose transmittance has been adjusted to the incident surface of the fly-eye lens 6 or a position near the incident surface. The illumination unevenness at the surface to be irradiated and / or at a position conjugate with the surface to be irradiated can be corrected. Such an optical member may be one in which the density changes continuously or one in which the transmittance is controlled by the number of dots. Such an optical member is disclosed in, for example, US Pat. No. 5,615,047 and
No. 54417 and U.S. Pat. No. 6,049,374.

In each of the above embodiments, a KrF excimer laser (wavelength: 248 nm) or A
wavelength of 1 such as rF excimer laser (wavelength: 193 nm)
Since the exposure light having a wavelength of 80 nm or more is used, the diffractive optical element can be formed of, for example, quartz glass. When a wavelength of 200 nm or less is used as the exposure light, the diffractive optical element is made of fluorite, quartz glass doped with fluorine, quartz glass doped with fluorine and hydrogen, a structure determination temperature of 1200 K or less and an OH group. Quartz glass having a concentration of 1000 ppm or more, quartz glass having a structure determination temperature of 1200 K or less and a hydrogen molecule concentration of 1 × 10 ¹⁷ molecules / cm ³ or more, a structure determination temperature of 1200 K or less and a chlorine concentration of 50 ppm or less. Quartz glass, structure determination temperature is 1200K or less and hydrogen molecule concentration is 1 × 1
0 ¹⁷ molecules / cm ³ or more and chlorine concentration of 50 ppm
It is preferable to use a material selected from the following group of quartz glass.

The structure determination temperature is 1200 K or less and
OH group concentration over 1000ppm
No. 2,770,224 filed by the present applicant.
And the structure determination temperature is 1200K or less.
And the hydrogen molecule concentration is 1 × 10 ¹⁷molecules / cm^ThreeAbove
Some quartz glass, the structure determination temperature is 1200K or less and
Quartz glass having a chlorine concentration of 50 ppm or less, and its structure
Determined temperature is 1200K or less and hydrogen molecule concentration is 1 × 1
0¹⁷molecules / cm^ThreeAbove and chlorine concentration is 50ppm
The following quartz glass is patented by the present applicant.
No. 2,936,138.

[0181]

As described above, in the illumination optical apparatus of the present invention, a secondary light source having a predetermined shape as a virtual image is formed at the position of the incident surface of the wavefront splitting optical integrator. Is illuminated at a predetermined ratio, the illumination condition can be changed almost continuously without substantial loss of light amount in the optical integrator.

Therefore, in the exposure apparatus incorporating the illumination optical device of the present invention, the illumination condition can be changed almost continuously without substantial loss of the light amount in the optical integrator, so that under the favorable illumination condition, And a good microdevice can be manufactured with high throughput.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of an exposure apparatus including an illumination optical device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view schematically showing a main part configuration from a diffractive optical element to an illumination field stop (mask blind) in the exposure apparatus of FIG.

FIG. 3 is a diagram illustrating that a circular secondary light source as a virtual image is formed on the incident surface of a fly-eye lens in the first embodiment.

FIG. 4 is a diagram schematically showing a configuration of a modification of the first embodiment.

FIG. 5 is a view showing a circular secondary light source as a virtual image formed on the incident surface of the fly-eye lens, and shows the smallest circular secondary light source in a so-called small σ state.

FIG. 6 is a diagram showing a circular secondary light source as a virtual image formed on an incident surface of a fly-eye lens, showing a circular secondary light source having an intermediate size in a so-called middle σ state. ing.

FIG. 7 is a diagram showing a circular secondary light source as a virtual image formed on the incident surface of the fly-eye lens, and shows the largest circular secondary light source in a so-called large σ state.

FIG. 8 is a diagram schematically showing a main configuration of an exposure apparatus including an illumination optical device according to a second embodiment of the present invention.

FIG. 9 is a diagram schematically showing a configuration of a modification of the second embodiment.

FIG. 10 is a view schematically showing a main configuration of an exposure apparatus including an illumination optical device according to a third embodiment of the present invention.

FIG. 11 is a diagram schematically illustrating a configuration of an exposure apparatus including an illumination optical device according to a fourth embodiment of the present invention.

FIG. 12 is a diagram schematically illustrating a configuration of an exposure apparatus including an illumination optical device according to a fifth embodiment of the present invention.

FIG. 13 is a view schematically showing a configuration of an exposure apparatus including an illumination optical device according to a sixth embodiment of the present invention.

FIG. 14 is a diagram schematically illustrating a configuration of an exposure apparatus including an illumination optical device according to a seventh embodiment of the present invention.

FIG. 15 is a diagram schematically showing a configuration of a first V-groove axicon and a second V-groove axicon arranged in an optical path of an afocal lens.

FIG. 16 is a diagram illustrating the operation of the first V-groove axicon and the second V-groove axicon in annular illumination.

FIG. 17 is a diagram illustrating the operation of the first V-groove axicon and the second V-groove axicon in quadrupole illumination.

FIG. 18 is a diagram illustrating the operation of the first V-groove axicon and the second V-groove axicon in circular illumination.

FIG. 19 is a view showing a form in which the second prism member of the first V-groove axicon and the first prism member of the second V-groove axicon are integrated.

FIG. 20 is a diagram showing a main configuration of a micro fly's eye lens including two types of microlens elements having different optical thicknesses along an optical axis AX.

FIG. 21 is a diagram showing an example of the arrangement of two types of micro lens elements constituting the micro fly's eye lens of FIG. 20;

FIG. 22 is a flowchart of a method for obtaining a semiconductor device as a micro device.

FIG. 23 is a flowchart of a method for obtaining a liquid crystal display element as a micro device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 4 Diffractive optical element 6 Fly-eye lens 7 Condenser lens 8 Mask blind (illumination field stop) 9 Imaging optical system 11 Afocal zoom lens 20 First diffractive optical element 21 First relay optical system 22 Second diffractive optical element 24 Second relay optical system 40 Micro fly-eye lens 41 Afocal zoom lens 50 Input means 51 Control system 52 to 57 Drive system 61 Afocal lens 62 Conical axicon 71, 72 V-groove axicon M Mask PL Projection optical system W Wafer

Continuation of the front page (72) Inventor Osamu Yatsu 3-2-3 Marunouchi, Chiyoda-ku, Tokyo Nikon Corporation F term (reference) 2H052 BA02 BA07 BA09 BA12 5F046 CB13 CB27

Claims (24)

[Claims] An illumination optical device for illuminating a surface to be illuminated based on a light beam from a light source, wherein the illumination optical device is arranged in an optical path between the light source and the surface to be illuminated,
A wavefront splitting type optical integrator having a large number of two-dimensionally arrayed minute lens elements; and a light guiding optical system arranged in an optical path between the optical integrator and the irradiated surface. An illumination optical device, wherein a secondary light source having a predetermined shape as a virtual image is formed at an incident surface position of an integrator. 2. The optical system according to claim 1, wherein a maximum incident angle of the light beam incident on the optical integrator is set such that an exit surface of the optical integrator is illuminated at a ratio of 60% or more. Illumination optics. 3. A light source having a predetermined cross-sectional shape or a predetermined light intensity distribution, which is disposed in an optical path between the light source and the optical integrator to convert a substantially parallel light beam from the light source into a light beam having a predetermined cross-sectional shape. A light beam converting element; and a light beam converting element disposed in an optical path between the light beam converting element and the optical integrator. The illumination optical device according to claim 1, further comprising a relay optical system for forming a secondary light source. 4. The light beam conversion element is disposed near a front focal plane of the relay optical system, and an exit surface position of the optical integrator is disposed near a rear focal plane of the relay optical system. An exit surface of the optical integrator is disposed almost optically conjugate with the light beam conversion element via the relay optical system, and an incident surface of the optical integrator is disposed on the light receiving surface via the light guide optical system and the optical integrator. The illumination optical device according to claim 3, wherein the illumination optical device is arranged substantially optically conjugate with the irradiation surface. 5. The relay optical system is configured as a variable power optical system having a variable focal length in order to change the overall size of the secondary light source formed as a virtual image at the position of the incident surface of the optical integrator. The illumination optical device according to claim 4, wherein: 6. The size of a light emitting portion of the light beam conversion element is set to d, and the focal length of the relay optical system is set to fr so that an emission surface of the optical integrator is illuminated at a ratio of 80% or more. The focal length of each microlens element constituting the optical integrator is fe,
The illumination optical device according to claim 4, wherein a condition of d> 0.8 · (fr / fe) de is satisfied, where the size of each minute lens element is de. 7. The size d of a light emitting portion of the light beam converting element
7. The illumination optical device according to claim 6, further comprising a light emitting portion changing means for changing the light emission portion. 8. The light-emitting portion changing means includes an afocal zoom lens arranged on a light source side of the light beam conversion element and for adjusting a size of a cross section of a light beam incident on the light beam conversion element. The illumination optical device according to claim 7, wherein: 9. The illumination optical device according to claim 3, wherein the light beam conversion element includes a diffractive optical element, a micro prism array, or a micro fly's eye lens. 10. The light beam converting element and the optical integrator are moved along a reference optical axis in order to adjust a magnification component of an illumination telecentric according to switching of illumination conditions. The illumination optical device according to claim 1. 11. A light source which is disposed in an optical path between the light source and the optical integrator to convert a substantially parallel light beam from the light source into a light beam having a predetermined cross-sectional shape or a light beam having a predetermined light intensity distribution. A first relay optical system that is disposed in an optical path between the light beam conversion element and the optical integrator and guides a light beam passing through the light beam conversion element to a predetermined surface; A light beam diverging element for diverging a light beam incident through the first relay optical system; and a light beam diverging element disposed in an optical path between the light beam diverging element and the optical integrator. And a second relay optical system that optically substantially conjugates the position of the exit surface of the optical integrator with the position of the optical integrator. 3. The illumination optical device according to 2. 12. The light beam converting element is arranged near a front focal plane of the first relay optical system, and the light diverging element is arranged near a rear focal plane of the first relay optical system. 12. The method according to claim 11, wherein
3. The illumination optical device according to claim 1. 13. The first relay optical system may be a variable magnification optical system having a variable focal length in order to change the overall size of the secondary light source formed as a virtual image at the position of the incident surface of the optical integrator. The illumination optical device according to claim 12, wherein the illumination optical device is configured. 14. A maximum exit angle of an emitted light beam from the light beam diverging element is set to θb, and an image forming magnification of the second relay optical system is set so that an output surface of the optical integrator is illuminated at a ratio of 80% or more. β, the focal length of each microlens element constituting the optical integrator is fe, and the size of each microlens element is de, θb> 0.8 · sin ⁻¹ (| β | · de / fe 12. The method according to claim 12, wherein the following condition is satisfied.
4. The illumination optical device according to 3. 15. A maximum incident angle of a light beam incident on the light beam diverging element in order to suppress a change in a maximum light emitting angle θb of the light beam from the light beam diverging element due to a change in a focal length of the first relay optical system. The illumination optical device according to claim 14, wherein θa is set substantially smaller than the maximum emission angle θb. 16. The illumination according to claim 11, wherein the light beam converting element and the light beam diverging element include a diffractive optical element, a micro prism array, or a micro fly's eye lens. Optical device. 17. A light beam conversion device which is disposed in an optical path between the light source and the light beam conversion device and converts a light beam from the light source into a light beam having a plurality of angle components with respect to a reference optical axis. 17. An image forming apparatus according to claim 11, further comprising an angle light beam forming means for making the light beam incident on the light source.
Item 15. The illumination optical device according to Item 1. 18. A light beam conversion device that is disposed in an optical path between the light beam conversion element and the first relay optical system and condenses a light beam from the light beam conversion element, and is substantially symmetric with respect to a reference optical axis from an oblique direction. A first optical system for causing light to enter a second predetermined surface; and an incident surface arranged near the second predetermined surface, the first
A second optical integrator of a wavefront division type for forming a large number of light sources based on a light beam from the optical system, wherein the numerical aperture of the light beam emitted from the light beam conversion element is the second numerical value.
The illumination optical device according to any one of claims 11 to 16, wherein a numerical aperture of a light beam from the multiple light sources formed by an optical integrator is set to be larger than the numerical aperture. 19. A light beam conversion element disposed in an optical path between the light beam conversion element and the first relay optical system for condensing a light beam from the light beam conversion element and obliquely symmetrically with respect to a reference optical axis. A first optical system for causing light to enter a second predetermined surface from a first optical system; and an incident angle changing element disposed in an optical path of the first optical system for changing an incident angle of an incident light beam on the second predetermined surface. The illumination optical device according to any one of claims 11 to 16, comprising: 20. The incident angle changing element includes an aspect ratio changing element for changing an aspect ratio of the incident light beam in order to change an incident angle of the incident light beam on the second predetermined surface along a predetermined direction. 20. The illumination optical device according to claim 19, wherein: 21. The optical system according to claim 11, wherein the luminous flux diverging element and the optical integrator are moved along a reference optical axis in order to adjust a magnification component of the illumination telecentric according to switching of illumination conditions. The illumination optical device according to claim 1. 22. Multi-light source forming means for forming a plurality of light sources based on the light beams from the light sources; a first group of light beams forming at least a first group of light sources among the plurality of light sources; By providing an optical path length difference that is substantially shorter than the temporal coherence distance of light between the second group of light beams forming the group of light sources, the first group of light beams and the second group of light beams The illumination optical device according to any one of claims 1 to 21, further comprising: a phase difference providing unit configured to provide a predetermined phase difference with the light beam. 23. The illumination optical device according to claim 1, further comprising: a projection optical system for projecting and exposing a mask pattern set on the surface to be irradiated onto a photosensitive substrate. An exposure apparatus, comprising: 24. An exposure step of exposing the pattern of the mask onto the photosensitive substrate by the exposure apparatus according to claim 23, and a developing step of developing the photosensitive substrate exposed in the exposure step. A method for manufacturing a micro device, comprising: