Illumination method, illumination apparatus and projection exposure apparatus

We claim:

1. A projection exposure apparatus comprising:

a light source for emitting a light beam for exposure;

an illumination optical system comprising optical fiber bundle portion including a plurality of bundled optical fibers having an entrance plane to which a light beam emitted from said exposing light source is incident, and a little optical fiber bundle portion including a plurality of little optical fiber bundles respectively having an outgoing plane; and

a projection exposure system for projecting a light beam passing through said illumination optical system and transmitting a mask or a reticle onto an object to be exposed as a pattern image of the mask or the reticle.

2. A projection exposure apparatus according to claim 1, further comprising control means for controlling relative positions of the outgoing planes of said little optical fiber bundles.

3. A projection exposure apparatus according to claim 1, further comprising a converging optical system for converging a light beam emitted from said exposing light source on the entrance side of the optical fibers in said illumination optical system.

4. A projection exposure apparatus according to claim 1, further comprising a mirror on the entrance side of the optical fibers in said illumination optical system.

5. A projection exposure apparatus according to claim 3, wherein said mirror is formed of a cylindrical mirror.

6. A projection exposure apparatus according to claim 1, wherein said converging optical system of said illumination optical system has an optical element for inputting a ring-shaped light beam on the entrance plane of said optical fiber bundle portion.

7. A projection exposure apparatus according to claim 1, wherein said exposing light source comprises a laser light source.

8. A projection exposure apparatus according to claim 1, wherein at least part of the entrance plane of the optical fiber bundle portion in said illumination optical system comprises a plurality of segments, wherein incident angles of the respective segments are different from each other with respect to the incident direction of a light beam, thereby providing a desired directivity to light beams exiting from the outgoing planes of the little optical fiber bundles.

9. A projection exposure apparatus according to claim 1 or 7, wherein optical path lengths of the optical fibers in said illumination optical system are made different to reduce the coherency of an illuminating light beam.

10. An illumination method comprising the steps of:

converging a light beam emitted from a light source;

passing the converged light beam through an optical fiber bundle formed by a plurality of optical fibers;

branching the light beam and passing the branched light beams through a plurality of branched little optical fiber bundles each having a little optical fiber bundle; and

emitting the light beams from respective outgoing planes of the plurality of little optical fiber bundles, the relative positions of which are controllable.

11. An illumination apparatus comprising:

an illuminating light source;

a converging optical system for converging the illuminating light emitted from said light source into a desired area;

optical fiber means comprising an optical fibre bundle portion to which the illuminating light converged by said converging optical system is incident and a plurality of little fiber bundle portions branched from said optical fiber bundle portion; and

control means for controlling relative positions of outgoing planes of the little optical fiber bundle portions of said optical fibers.

12. A projection exposure apparatus comprising:

an exposing light source;

an illumination optical system for irradiating a mask or a reticle with a light beam emitted from said exposing light source including:

optical fiber means comprising an optical fiber bundle portion including a plurality of optical fibers and having an entrance plane from which a light beam emitted from said exposing light source enters, and a little optical fiber bundle portion including a plurality of little optical fiber bundles each having an outgoing plane; and

a converging and diverging optical system for converging particular angle components of an incident light beam exiting from said optical fiber means and diverging the converged components; and

a projection optical system for projecting a light beam passing through said illumination optical system and transmitting a mask or a reticle onto an object to be exposed as a pattern image of the mask or the reticle.

13. A projection exposure apparatus according to claim 12, wherein said illumination optical system further comprises control means for controlling relative positions of the outgoing planes of said little optical fiber bundle portion.

14. A projection exposure apparatus according to claim 12, wherein the outgoing end of the optical fiber means in said illumination optical system is in an optically conjugated relationship with the entrance plane of said converging and diverging optical system.

15. A projection exposure apparatus according to claim 12, further comprising optically modifying means for modifying a light beam incident to said optical fiber means in said illumination optical system by refraction or reflection.

16. A projection exposure apparatus according to claim 12, further comprising optically modifying means for modifying a light beam incident to said converging and diverging optical system in said illumination optical system by refraction or reflection.

17. A projection exposure apparatus according to claim 15, wherein said optical fiber means has such a numerical aperture that an illuminating light beam having an inclination modified by the optically modifying means can sufficiently transmit said converging and diverging optical system.

18. A projection exposure apparatus according to claim 16, wherein said optical fiber means has such a numerical aperture that an illuminating light beam having an inclination modified by the optically modifying means can sufficiently transmit said converging and diverging optical system.

19. A projection exposure apparatus according to claim 12, further comprising optical means for establishing the relationship of Keller illumination or optical infinity between the outgoing plane of said optical fiber means in said illumination optical system and the entrance plane of said converging and diverging optical system.

20. A projection exposure apparatus according to claim 19, further comprising modifying means for modifying the diameter of light beams exiting from said optical fiber means in said illumination optical system to lead the light beam into said converging and diverging optical system.

21. A projection exposure apparatus according to claim 19, further comprising optically modifying means for modifying a light beam incident to said converging and diverging optical system in said illumination optical system by refraction or reflection.

22. A projection exposure apparatus according to claim 12, 13, 14, 16, 18, 19, 20 or 21, wherein said converging and diverging optical system is formed by a rod lens.

23. A projection exposure method comprising the steps of:

leading a light beam emitted from an exposing light source into an entrance plane of optical fiber means including an optical fiber bundle portion formed by a plurality of bundled optical fibers having said entrance plane, and a little optical fiber bundle portion formed by a plurality of little optical fiber bundles branched from said optical fiber bundle portion and each having an outgoing plane;

converging particular angle components of light beams exiting from said outgoing planes of said optical fiber means and diverging the converged components by a converging and diverging optical system, and irradiating a mask or a reticle with the light beam through said converging and diverging optical system; and

projecting the light beam transmitting the mask or the reticle onto an object to be exposed as a pattern image of the mask or the reticle.

24. An illumination optical apparatus comprising:

a light source;

optical fiber means including an optical fiber bundle portion formed by a plurality of bundles optical fibers having an entrance plane to which a light beam emitted from said light source is incident, and a little optical fiber bundle portion formed by a plurality of little optical fiber bundles branched from said optical fiber bundle portion and each having an outgoing plane; and

a converging and diverging optical system for converging particular angle components of a light beam exiting from said optical fiber means and entering thereinto and diverging the converged components.

25. An illumination optical apparatus according to claim 24, further comprising control means for controlling relative positions of the outgoing planes of said little optical fiber bundle portion.

26. An illumination optical apparatus according to claim 24, wherein the outgoing end of said optical fiber means and the entrance plane of said converging and diverging optical system are in an optically conjugated relationship.

27. An illumination optical apparatus according to claim 24, further comprising optically modifying means for modifying a light beam entering into said optical fiber means by refraction or reflection.

28. An illumination optical apparatus according to claim 24, further comprising optical modifying means for modifying a light beam entering into said converging and diverging optical system.

29. An illumination optical apparatus according to claim 24 further comprising optical means for establishing the relationship of Keller illumination or optical infinity between the outgoing plane of said optical fiber means in said illumination optical system and the entrance plane of said converging and diverging optical system.

30. An illumination optical apparatus according to claim 29, further comprising modifying means for modifying the diameter of a light beam exiting from said optical fiber means to pass the light beam into said converging and diverging optical system.

31. An illumination optical apparatus according to claim 29, further comprising optically modifying means for modifying a light beam incident to said converging and diverging optical system by refraction or reflection.

32. A projection exposure apparatus according to claim 24, wherein said converging and diverging optical system is formed by a rod lens.

Description Submit all comments and votes

BACKGROUND OF THE INVENTION

The present invention relates to methods and apparatus for exposure illumination for use in projection exposure apparatus for producing semiconductor chips, and more particularly, to projection exposure apparatus, illumination methods and illumination apparatus which control the directivity of illuminating light in accordance with the size and shape of a pattern to be exposed or detected as well as the kind of a mask, a reticle or a wafer, so as to allow a pattern to be exposed or detected in an appropriate condition.

Patterns of semiconductor integrated circuits tending to be increasingly fine have advanced to an extent that the pattern width approaches to the wavelength of light. Although exposing methods using X-rays or electron rays in place of light beams have been developed, these methods are inferior in mass productivity as compared with the light exposing method which allows a large number of integrated circuit chips to be exposed for a short time, particularly for producing memories and so on which are in great demand, and therefore encounter difficulties in mass-producing inexpensive memories. In such circumstances, techniques have been developed in recent years for providing a mask or a reticle used in a conventional i-line reduction projection exposure apparatus (i-line stepper) with a phase shift portion so as to significantly improve the resolution of a pattern as compared with a conventionally used normal reticle. Further, a technique, as described in JP-A-61-91662, has been developed for improving the resolution of patterns, even without employing such a special reticle, by forming an ring-shaped light beam for illuminating a reticle on an entrance pupil of a reduction projection lens so as to have high spatial frequency spectrum of the light transmitting the reticle pass through an entrance pupil of an imaging lens for exposure.

When a method of improving the resolution of patterns as described above is to be employed, if a conventionally used semiconductor exposure apparatus (i-line stepper) is used as it is, a problem arises that a so-called .sigma. value indicative of the illumination directivity of a light beam illuminating a reticle (.sigma.=the ratio of extension of illuminating light on a pupil of an imaging lens for exposure to the diameter of the pupil of the lens) does not coincide with the .sigma. value indicative of the illumination directivity optimal to the resolution improving method.

SUMMARY OF THE INVENTION

To solve the above problem inherent to the prior art, it is an object of the present invention to provide projection exposure apparatus, illumination methods and illumination apparatus which are capable of readily selecting and controlling illuminating light optimal to each of various resolution improving methods and utilizing exposing light emitted from an exposing light source without wasting it.

Specifically, the present invention provides a projection exposure apparatus which is characterized by comprising a light source for emitting a light beam for exposure; an illumination optical system comprising optical fiber bundle portion including a plurality of bundled optical fibers having an entrance plane to which a light beam emitted from the exposing light source is incident, and a little optical fiber bundle portion including a plurality of little optical fiber bundles respectively having an outgoing plane; and a projection exposure system for projecting a light beam passing through the illumination optical system and transmitting a mask or a reticle onto an object to be exposed as a pattern image of the mask or the reticle.

It is also an object of the present invention to provide a projection exposure apparatus which is characterized by comprising a light source for emitting a light beam for exposure; an illumination optical system for irradiating a mask or a reticle with a light beam emitted from the exposing light source including optical fiber means comprising an optical fiber bundle portion including a plurality of optical fibers and having an entrance plane from which the light beam emitted from the exposing light source enters and a little optical fiber bundle portion including a plurality of little optical fiber bundles each having an outgoing plane, and a converging and diverging optical system for converging particular angle components of an incident light beam exiting from the optical fiber means and diverging the converged components; and a projection optical system for projecting a light beam passing through the illumination optical system and transmitting a mask or a reticle onto an object to be exposed as a pattern image of the mask or the reticle.

To achieve the above object, the present invention provides a projection exposure apparatus which is characterized by comprising a light source for emitting a light beam for exposure; an illumination optical system for irradiating a mask or a reticle with a light beam emitted from the exposing light source including optical fiber means comprising an optical fiber bundle portion including a plurality of optical fibers and having an entrance plane from which a light beam emitted from the exposing light source enters and a little optical fiber bundle portion including a plurality of little optical fiber bundles each having an outgoing plane; and a projection optical system for projecting a light beam passing through the illumination optical system and transmitting a mask or a reticle onto an object to be exposed as a pattern image of the mask or the reticle. More specifically, the projection exposure apparatus of the present invention is so constructed that a light beam emitted from the light source is converged to enter into an entrance plane on one side of the optical fiber bundle portion comprising a plurality of bundled optical fibers, and this optical fiber bundle portion is branched into a little optical fiber bundle portion comprising a plurality of little bundles of optical fibers. Further, when an object to be exposed such as a mask or a reticle is irradiated with light beams exiting from the plurality of little optical fiber bundles, the plurality of little optical fiber bundles are constructed such that relative positions of outgoing planes thereof are controllable.

By disposing a cylindrical mirror which has a symmetrical axis parallel to the normal of the entrance end plane of the optical fiber bundle portion and a mirror surface having a high reflectivity with respect to a light beam for exposure in the vicinity of the entrance plane such that the symmetry axis substantially coincides with the center of the outer shape of the entrance end plane, a light beam emitted from the light source can be led, in a ring shape, into the entrance end plane of the optical fiber bundle. Alternatively, by disposing, in the vicinity of the entrance end plane, a transparent member having a rotatory symmetry axis parallel to the normal of this entrance end plane and a concave cross-section, cut by a plane including this normal, which is substantially defined by straight lines, a light beam emitted from the light source can also be made to enter, in a ring shape, into the entrance end plane of the optical fiber bundle. This ring-shaped illuminating light can be obtained from the outgoing planes of the little optical fiber bundles by preventing light beams from entering into a central portion of the entrance plane of the optical fiber bundle. Further, these cylindrical mirror and the transparent member having a concave cross-section defined by straight lines can be automatically inserted into the vicinity of the entrance end plane of the optical fiber bundle and removed therefrom.

In the above structure, for a light source such as an excimer laser which emits a light beam with a high coherency and directivity, the lengths of the respective optical fibers constituting the optical fiber bundle are made different in accordance with the coherency between respective positions of the cross-section of a laser beam, to vary the optical paths, reduce the coherency of an irradiating light beam obtained from the outgoing end, and provide a uniform illuminating light beam. Also, when a laser beam with a high directivity is to enter into the entrance end plane of the optical fiber bundle, this entrance end plane is divided into a plurality of segments such that each segment has a different incident angle with respect to an entering laser beam, thereby making it possible to provide an irradiating light beam exiting from the outgoing end of the optical fiber bundle with a desired directivity required to particular illumination.

More specifically, the present invention is characterized by converging a light beam emitted from a light source to enter into one end plane of an optical fiber bundle formed by a plurality of bundled optical fibers, controlling relative positions of end planes of a plurality of little optical fiber bundles which are formed on the opposite side of the optical fiber bundle, and irradiating an object to be illuminated with light beams exiting from the plurality of little optical fiber bundles. The present invention is also characterized in that the number of the plurality of little optical fiber bundles is selected to be five or more, their end planes are positioned in a desired plane, and movement of the end planes caused by the control of the relative positions is made along the desired plane. The present invention is also characterized by simultaneously controlling the relative positions of the plurality of little optical fiber bundles by a single driving system. The present invention is also characterized in that the relative positions of the respective end planes of the little optical fiber bundles are similarly changed by the control of the relative positions of the plurality of little optical fiber bundles. The present invention is also characterized in that the relative positions of the end planes of the little optical fiber bundles are radially changed around a point on a plane formed by the end planes of the plurality of little optical fiber bundles by the control of the relative positions of the plurality of little optical fiber bundles. The present invention is also characterized in that the entrance end plane of the optical fiber bundle, which is one end plane thereof, has a circular or polygonal outer shape, and a cylindrical mirror which has a symmetry axis parallel to the normal of this entrance end plane and a mirror surface having a high reflectivity with respect to a light beam for exposure is disposed in the vicinity of the entrance end plane such that the symmetry axis thereof substantially coincides with the center of the outer shape of the entrance end plane of the optical fiber bundle, whereby a light beam emitted from the light source is formed in a ring shape and enters into the entrance end plane of the optical fiber bundle with a high light utilizing efficiency. The present invention is also characterized in that the cylindrical mirror can be automatically inserted in the vicinity of the entrance end plane of the optical fiber bundle and removed therefrom. The present invention is also characterized in that the entrance end plane, which is one end plane of the optical fiber bundle, has a circular or polygonal outer shape, and a transparent member, having a rotatory symmetry axis parallel to the normal of this entrance end plane and a concave cross-section, cut by a plane including this normal, which is substantially defined by straight lines, is disposed in the vicinity of the entrance end plane, whereby a light beam emitted from the light source is formed in a ring shape and enters into the entrance end plane of the optical fiber bundle with a high light utilizing efficiency. The present invention is also characterized in that the transparent member can be automatically inserted in the vicinity of the entrance and plane of the optical fiber bundle and removed thereform. The present invention is also characterized in that on the entrance end plane which is one end plane of the optical fiber bundle, a space between light transmitting portions of the respective optical fibers is filled with a high reflective material to reduce heat generation caused by the absorption of light incident to the entrance end plane. The present invention is also characterized in that the entrance end plane, which is one end plane of the optical fiber bundle, has the shape of light transmitting portions of the respective optical fibers made different from the shape of light emitting portions on the outgoing end plane of the respective optical fibers. The present invention is also characterized in that a laser light source is employed as a light source, and a light beam emitted from the laser light source, after providing the light beam with a desired beam diameter, is led into one end plane of the optical fiber bundle formed by a plurality of bundles optical fibers. The present invention is also characterized in that the lengths of the respective optical fibers constituting the optical fiber bundle are made different in accordance with the coherency of a laser beam emitted from the laser light source on the entrance end plane of the optical fiber bundle, so as to reduce the coherency of an illuminating light beam obtained from the outgoing end to achieve the uniformity of illumination. The present invention is also characterized in that after the optical paths have been changed in respective parts within the beam cross-section in accordance with the coherency between respective positions on the beam cross-section of a laser beam emitted from the laser light source, light beams from the respective parts are led into the optical fiber bundle. The present invention also provides an illumination method, wherein after a laser beam emitted from the laser light source is provided with a desired beam diameter, one end plane of an optical fiber bundle formed by a plurality of bundled optical fibers is inserted in the optical path, and a laser beam exiting from the opposite end plane of the optical fiber bundle is employed for illumination, which is characterized in that the entrance end plane of the optical fiber bundle comprises a plurality of portions, and the respective portions are constructed such that the angle formed by the normal of the entrance end plane with the entrance direction of the laser beam, i.e., the incident angle varies in the respective portions, whereby the exiting light beam from the outgoing end plane is provided with a desired light directivity for illumination.

Further, to achieve the above objects, the present invention establishes, in the projection exposure apparatus, optically conjugated relationship between the outgoing end of the optical fiber means in the illumination optical system and the entrance plane of the converging and diverging optical system.

Further, to achieve the above objects, the present invention provides the projection exposure apparatus with optically modifying means for modifying a light beam incident to the optical fiber bundle in the illumination optical system by refraction or reflection.

Further, to achieve the above objects, the present invention provides the projection exposure apparatus with optically modifying means for modifying a light beam incident to the converging and diverging optical system in the illumination optical system by refraction or reflection.

Further, to achieve the above objects, the optical fiber in the projection exposure apparatus has such a numerical aperture (NA) that an illuminating light beam having an inclination modified by the optically modifying means can sufficiently transmit the converging and diverging optical system.

Further, to achieve the above objects, the converging and diverging optical system in the projection exposure apparatus has such a numerical aperture (NA) that an illuminating light beam having an inclination modified by the optically modifying means can sufficiently transmit the converging and diverging optical system.

Further, to achieve the above objects, the present invention provides the projection exposure apparatus with optical means for establishing the relationship of Keller illumination or optical infinity between the outgoing plane of the optical fiber in the illumination optical system and the entrance plane of the converging and diversing optical system.

Further, to achieve the above objects, the present invention provides a projection exposure method comprising the steps of: leading a light beam emitted from an exposing light source into an entrance plane of optical fiber means including an optical fiber bundle portion formed by a plurality of bundled optical fibers having the entrance plane, and a little optical fiber bundle portion formed by a plurality of little optical fiber bundles branched from the optical fiber bundle portion and each having an outgoing plane; converging particular angle components of light beams exiting from the outgoing planes of the optical fiber means and diverging the converged components by a converging and diverging optical system, and irradiating a mask or a reticle with the light beam through the converging and diverging optical system; and projecting the light beam transmitting the mask or the reticle onto an object to be exposed as a pattern image of the mask or the reticle.

Further, to achieve the above object, the present invention provides an illumination optical apparatus comprising: a light source; optical fiber means including an optical fiber bundle portion formed by a plurality of bundles optical fibers having an entrance plane to which a light beam emitted from the light source is incident, and a little optical fiber bundle portion formed by a plurality of little optical fiber bundles which are branched from the optical fiber bundle portion and each have an outgoing plane; and a converging and diverging optical system for converging particular angle components of a light beam exiting or emitting from the optical fiber means and entering thereinto and diverging the converged components.

The above-mentioned means can readily provides illumination with a relatively high directivity, i.e., a small .sigma. value suitable for a phase shift reticle, ring-shaped illumination for forming a high resolution pattern by a normal reticle, or illumination with a conventional directivity. The above-mentioned means, when employed, allows a light beam emitted from the light source to irradiate an object to be exposed with a high light utilizing efficiency.

When an excimer laser or the like is to be employed in future for reducing exposure wavelength to attend to patterns drawn with thinner line widths, the above-mentioned methods readily solve problems of ununiform illumination due to the coherency and directivity of the laser, thereby making it possible to readily realize a variety of illumination with little waste of light also in an excimer laser stepper.

Thus, the present invention can be implemented in an illumination system for use in exposure, test, display and so on of patterns to readily provide optimal illumination in the relationship between the shape and size of a particular pattern to be exposed, tested or displayed and optical systems used for such exposure, testing and display purposes in a relatively simple structure as well as to easily modify the optimal illumination in accordance with changes in the optical systems. In this manner, illuminating light of a conventional fixed illumination system need not be partially shielded, and a desired illumination directivity and illuminating light distribution can be realized without decreasing the light utilizing efficiency, thereby providing an exposure apparatus or a testing apparatus presenting a improved throughput. Also, in a display unit, a clear display can be accomplished or a light source with a smaller power is sufficient for the same brightness as before.

The above-mentioned means can readily provides illumination with relatively high directivity, i.e., a small .sigma. value suitable for a phase shift reticle, ring-shaped illumination for forming a high resolution pattern by a normal reticle, or illumination with a conventional directivity. Further, the above-mentioned means, when employed, allows a light beam emitted from the light source to irradiate an object to be exposed with a high light utilizing efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an exemplary optical system of an exposure illumination apparatus employing a mercury lamp as a light source for use in a projection exposure apparatus according to a first embodiment of the present invention;

FIG. 2 is illustrates a mechanism for changing relative positions of little optical fiber bundles of an illumination apparatus according to the present invention;

FIGS. 3A-3D illustrate positions of little optical fiber bundles in the mechanism for changing relative positions of little optical fiber bundles;

FIGS. 4A and 4B show how a variety of illumination methods are realized by a projection exposure apparatus employing an illumination optical system according to the present invention;

FIGS. 5A and 5B illustrate a projection exposure apparatus comprising the illumination optical system according to the present invention;

FIG. 6 is illustrates a first example for realizing an illuminating beam in a ring in an illumination apparatus for use in a projection exposure apparatus or the like based on the first embodiment of the present invention;

FIGS. 7A and 7B illustrate the example of FIG. 6 in greater detail;

FIG. 8 illustrates a second example for realizing an illuminating beam in a ring in an illumination apparatus for use in a projection exposure apparatus based on the first embodiment of the present invention;

FIGS. 9A and 9B illustrate the example of FIG. 8 in greater detail;

FIGS. 10A and 10B illustrate an embodiment of an illumination apparatus for use in a projection exposure apparatus or the like based on the first embodiment of the present invention which has optical diverging optical parts on outgoing ends of little optical fiber bundles;

FIGS. 11A and 11B show, by way of example, how the diameter of an optical fiber is changed;

FIGS. 12A and 12B are plan views of optical fiber entrance ends where a high reflective material is used between adjacent optical fibers;

FIGS. 13A and 13B illustrate the first embodiment which employs a laser as a light source;

FIGS. 14A-14E illustrate the relationship between an entrance end and an outgoing end of optical fibers in the embodiment which employs a laser as a light source;

FIG. 15 illustrates the embodiment which employs two optical fiber bundles;

FIGS. 16A-16D are cross-sectional views of optical paths in the embodiment of FIG. 15;

FIGS. 17A-17D show how outgoing ends of little optical fiber bundles of the present invention are changed by the mechanism for changing relative positions of little optical fiber bundles;

FIGS. 18A-18C show how outgoing ends of other little optical fiber bundles of the present invention are changed by the mechanism for changing relative positions of little optical fiber bundles;

FIG. 19 illustrates a second case of the embodiment which employs a laser as a light source;

FIGS. 20A-20C illustrate cross-sectional views of light paths in the embodiment of FIG. 19;

FIG. 21 illustrates a third case of the embodiment of an illumination apparatus which employs a laser as a light source;

FIGS. 22A-22F illustrates cross-sectional views of light paths in the embodiment of FIG. 21;

FIGS. 23A-23F illustrate incident angles of a light beam entering an optical fiber and outgoing angles (conditions of diverging light beams) for showing the principles of the embodiments shown in FIGS. 21 and 22A-2F;

FIGS. 24A and 24B illustrate an embodiment of a reduction projection exposure apparatus based on the first embodiment of the present invention, wherein a variable filter is mounted on the position of the entrance pupil of a reduction exposure lens;

FIG. 25 illustrates an embodiment of a pattern testing apparatus to which an illumination apparatus of the present invention is applied;

FIG. 26 illustrates a projection exposure apparatus which comprises the exposure illumination system based on a second embodiment of the present invention;

FIGS. 27A-27D are diagrams for explaining several cases where relative positions of the little optical fiber bundles shown in FIG. 26 are changed;

FIG. 28 illustrates a projection exposure apparatus which comprises the exposure illumination system based on the second embodiment of the present invention;

FIG. 29 illustrates a projection exposure apparatus which comprises an illumination modifying means based on the second embodiment of the present invention;

FIGS. 30A-30F illustrate examples of illumination modifying means utilizing reflection according to the second embodiment of the present invention;

FIGS. 31A-31F illustrate examples of illumination modifying means utilizing refraction according to the second embodiment of the present invention;

FIGS. 32A and 32B are explanatory diagrams for showing the rationalization of a rod lens according to the second embodiment of the present invention; and

FIG. 33 illustrates a projection exposure apparatus which comprises an illumination modifying means based on the second embodiment of the present invention;

FIG. 34 illustrates a projection exposure apparatus which comprises an illumination modifying means based on the second embodiment of the present invention;

FIGS. 35A and 35B illustrate an illumination modifying means employing a lens based on the second embodiment of the present invention; and

FIG. 36 illustrates a projection exposure apparatus which comprises the illumination modifying means based on the second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will hereinafter be described in detail based on the accompanying drawings.

To begin with, a first embodiment of the present invention will be explained with reference to FIGS. 1-25.

FIG. 4A illustrates an exposure illumination optical system in a projection exposure apparatus. An i-line beam em