Illuminating apparatus

The present invention relates to an illuminating apparatus for illuminating an illuminated object in an arcuate pattern and, more particularly, to an illuminating apparatus suitably applicable to exposure apparatus suitably used in transferring a circuit pattern on a photomask (mask or reticle) through a reflection type imaging apparatus onto a substrate such as a wafer by the mirror projection method, for example of an X-ray optical system. The illuminating apparatus of the present invention can illuminate the illuminated surface in an arcuate pattern with uniform intensity. Exposure apparatus provided with the illuminating apparatus of the present invention can obtain an image with uniform exposure over the entire arcuate surface as the illuminated surface, so that the pattern on the mask located on the illuminated surface can be accurately transferred with high throughput onto the substrate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an illuminating apparatus for illuminating 
an object to be illuminated in an arcuate pattern, and more particularly, 
the invention relates to an illuminating apparatus suitably applicable to 
exposure apparatus for transferring a circuit pattern on a photomask (mask 
or reticle) through a reflection-type imaging apparatus onto a substrate 
such as a wafer by the mirror projection method, for example an X-ray 
optical system. 
2. Related Background Art 
In exposure in conventional semiconductor fabrication, the circuit pattern 
formed on a surface of the photomask (hereinafter referred to as a mask) 
as the object plane is projected to be transferred through the imaging 
apparatus onto the substrate such as a wafer (hereinafter referred to as a 
substrate). When exposure light is, for example, X-rays, the imaging 
apparatus is composed of reflecting mirrors and only an arcuate best image 
region off the axis of an imaging optical system is utilized, thereby 
projection-transferring only an arcuate region on the mask onto the wafer. 
Further, the entire circuit pattern on the mask is transferred onto the 
wafer while moving the mask and wafer in a certain fixed direction. 
This scan type exposure has advantages of relatively high throughput and 
high resolution. 
For exposure of this type, there have been demands to develop an 
illumination optical system that can illuminate the entire arcuate region 
on the mask in a uniform manner and with a constant numerical aperture 
(NA), and the applicant of this application proposed the illumination 
optical system that could uniformly illuminate the mask in an arcuate 
pattern, in Japanese Patent Application No. 4-242486 (Japanese Patent 
Application Laid-Open No. 6-97047). 
FIG. 5 and FIG. 6 show the optical system as described in the Japanese 
Patent Application No. 4-242486. In the drawings, PA represents a 
parabola, the origin is located at the vertex O of the parabola PA, the Y 
axis is taken along the axis of symmetry Ax.sub.0 of the parabola passing 
through the vertex O, and the X axis is taken along an axis being 
perpendicular to the axis of symmetry Ax.sub.0 (hereinafter referred to as 
the Y axis) and passing through the vertex O. 
As shown in FIG. 5, a meridional cross section of a special reflecting 
mirror 3 is a part of the parabola PA, and this special reflecting mirror 
3 consists of a part of a parabolic-toric body of rotation obtained by 
rotating the parabola about a base axis Ax.sub.1 (an axis perpendicular to 
the symmetry axis Y) passing through a position Y.sub.0 that is a 
predetermined distance along the symmetry axis Y from the vertex O. 
Namely, as shown in FIG. 6, the special reflecting mirror 3 is an arcuate 
region that is a part of a belt zone between two latitudes 31, 32, of the 
parabolic-toric body of rotation. 
The function of the special reflecting mirror 3 as to light beams in the 
meridional direction is described by reference to FIG. 5. Here, the light 
beams in the meridional direction mean those in the plane including the 
base axis Ax.sub.1 of the special reflecting mirror 3 (i.e., in the 
meridional plane), while light beams in the sagittal direction mean those 
in a plane (the sagittal plane) perpendicular to the meridional plane. 
Supposing an unrepresented optical system forms a light source image (or 
light source) 1 of a predetermined size at a predetermined position on the 
base axis Ax.sub.1, beams from an arbitrary point on the light source 
image (or light source) 1 are converted into parallel beams by a 
converging or condensing function of the special reflecting mirror 3. 
For example, beams from the center a of the light source image (or light 
source) 1 are converted into parallel beams by the special reflecting 
mirror 3 to illuminate a region BA.sub.0 of an illuminated surface 
normally thereto, but beams from a lower point b of the light source image 
(or light source) 1 are converted into parallel beams by the special 
reflecting mirror 3 to obliquely illuminate the region BA.sub.0 of the 
illuminated surface from the upper right. Further, beams from an upper 
point c on the light source image (or the light source) 1 are converted 
into parallel beams by the special reflecting mirror 3 to obliquely 
illuminate the region BA.sub.0 of the illuminated surface from the upper 
left. 
As described, the beams from the respective points on the light source 
image (or light source) 1 are converted into the parallel beams by the 
special reflecting mirror 3 to uniformly illuminate the region BA.sub.0 of 
the illuminated surface in a superimposed manner. 
Checking the numerical aperture in the meridional direction by the special 
reflecting mirror 3 in this case, the parallel beams from the light source 
image (or light source) 1 parallel to the optical axis AX.sub.20 (the 
beams represented by the solid lines) are converged by the special 
reflecting mirror 3 at the center on the region BA.sub.0 of the 
illuminated surface under a numerical aperture NA.sub.M 
(=sin.theta..sub.M), and the parallel beams from the light source image 
(or light source) 1 having a divergent angle .epsilon..sub.1 relative to 
the optical axis AX.sub.20 (the beams represented by the dashed lines) are 
converged by the special reflecting mirror 3 at the left edge on the 
region BA.sub.0 of the illuminated surface under the numerical aperture 
NA.sub.M. Further, the parallel beams from the light source image (or 
light source) 1 having a divergent angle .epsilon..sub.2 
(=.epsilon..sub.1), which is symmetric in direction with the divergent 
angle .epsilon..sub.1 but equal in angle to the divergent angle 
.epsilon..sub.1, are converged by the special reflecting mirror 3 at the 
right edge on the region BA.sub.0 of the illuminated surface under the 
numerical aperture NA.sub.M. The optical axis AX.sub.20 is bent 90 degrees 
by the special reflecting mirror 3. 
It is thus understood that parallel beams having an arbitrary divergent 
angle from the light source image (or light source) 1 are converged under 
the constant numerical aperture NA.sub.M at any position in the meridional 
direction on the region BA.sub.0 of the illuminated surface and that the 
principal rays (p.sub.a, p.sub.b, p.sub.c) of the parallel beams from the 
light source image (or light source) 1 are always parallel to the optical 
axis Ax.sub.20 while maintaining the telecentricity. 
The function of the special reflecting mirror 3 in the sagittal direction 
is next described referring to FIG. 6. Parallel beams 21 from the light 
source image (or light source) 1 formed on the base axis Ax.sub.1 are 
converged by the special reflecting mirror 3 on the region BA.sub.0 of the 
illuminated surface, and parallel beams 22 from the light source image (or 
light source) 1, outgoing at a divergent angle .phi. from the parallel 
beams 21, are converged by the special reflecting mirror 3 on a region 
BA.sub.1 of the illuminated surface. 
Here, let us check beams in the sagittal direction out of the beams from 
the light source image (or light source) 1 forming the region BA.sub.1 of 
the illuminated surface. Similarly to the case of FIG. 5, parallel beams 
having an arbitrary divergent angle from the light source image (or light 
source) 1 are converged under the constant numerical aperture NA.sub.M at 
any position in the meridional direction on the region BA.sub.1 of the 
illuminated surface and the principal rays of the parallel beams from the 
light source image (or light source) 1 are always parallel to the optical 
axis Ax.sub.21 while maintaining the telecentricity. 
Therefore, when the parallel beams from the light source image (or light 
source) 1 formed on the base axis Ax.sub.1 are outgoing radially in 
directions toward the arc of the special reflecting mirror 3 (or in 
directions towards the latitudes 31, 32 of the parabolic-toric body of 
rotation), an arcuate illumination region BF is formed in a state where 
the telecentricity is maintained. 
The arcuate illumination region BF corresponds to the illuminated surface, 
and the light source image or light source is located at infinity with 
respect to the illuminated surface. Here, a projection optical system 
telecentric on the entrance side is provided below the illuminated 
surface, and a light source image is formed at the position of the 
entrance pupil of the projection optical system. It is thus understood 
that the illuminated surface is illuminated under the so-called Kohler 
illumination. 
In the above illuminating apparatus, the light source image (or light 
source) 1 formed on the base axis Ax.sub.1 is produced, for example, by an 
optical integrator. In order to construct an optical system in the short 
wavelength region including X-rays etc., all elements in the optical 
system must be reflection type members. Therefore, the optical integrator 
used in the short wavelength region must be of a reflection type. 
An example of the reflection type optical integrator is a fly's eye mirror 
in which a plurality of curved surface mirrors are arranged in a 
two-dimensional array, as shown in FIG. 8A. The plurality of curved 
surface mirrors are concave surface mirrors, for example as shown in the 
cross section of FIG. 8B (which is a cross section along e-e' of FIG. 8A). 
Such a fly's eye mirror forms the light source image (or light source) in 
which fine light sources 9 are arranged in a two-dimensional array (FIG. 
8C). 
Here is described a case where the above illumination optical system (as 
disclosed in Japanese Patent Application No. 4-242486) is applied to a 
soft X-ray exposure apparatus, by reference to FIGS. 7A and 7B. FIG. 7A 
shows a cross section in the meridional direction, of the illumination 
optical system. Although the drawings show a transmission type optical 
system in order to facilitate the description, the optical system is of a 
reflection type in fact. 
X-rays diverging from an X-ray source (an example of the light source in a 
light source system) 4 are converted into parallel beams by the reflecting 
mirror 5 and the reflection type optical integrator 2 forms the light 
source image (or light source) composed of the plurality of fine light 
sources 9. Further, X-rays diverging from the light source image (or light 
source) are converted into parallel beams by the special reflecting mirror 
3 to illuminate the illuminated surface BF. 
In this case, a divergent angle .theta..sub.i1 of the X-rays diverging from 
the light source image (or light source) is determined by a width L.sub.1 
of the illuminated region and a distance between the light source image 
(or light source) and the special reflecting mirror 3. For example, 
supposing L.sub.1 is 2 mm and the distance is 120 mm, the divergent angle 
.theta..sub.i1 is about 1.degree.. 
Next described using FIG. 7B is a cross section in the sagittal direction, 
of the illumination optical system. X-rays diverging from the X-ray source 
4 are converted into parallel beams by the reflecting mirror 5, and the 
reflection type optical integrator 2 forms the light source image (or 
light source) composed of the plurality of fine light sources 9. Further, 
X-rays diverging from the light source image (or light source) are 
converted into parallel beams by the special reflecting mirror 3 to 
illuminate the illuminated surface BF. 
In this case, a divergent angle .theta..sub.i2 of the X-rays diverging from 
the light source image (or light source) is determined by a width L.sub.2 
of the illuminated region and a distance between the light source image 
(or light source) and the special reflecting mirror 3. For example, 
supposing L.sub.2 is 2 mm and the distance is 120 mm, the divergent angle 
.theta..sub.i2 is about 60.degree.. 
Therefore, in such a case, the reflection type optical integrator needs to 
be constructed to have largely different divergent angles in the sagittal 
direction and in the meridional direction. 
An example of the reflection type optical integrator having such largely 
different divergent angles is a fly's eye mirror as shown in FIG. 9A. A 
plurality of curved surface mirrors constituting the fly's eye mirror each 
are, for example, a rectangular part cut out from a spherical mirror. 
Cross sections thereof are those as shown in FIG. 9B1 and FIG. 9B2. Here, 
FIG. 9B1 is a cross section along f-f' in FIG. 9A, and FIG. 9B2 a cross 
section along g-g' in FIG. 9A. 
The light source image (or light source) formed by such a fly's eye mirror, 
however, includes different numbers of fine light sources 9 in the 
meridional direction and in the sagittal direction, as shown in FIG. 9C. 
Such a difference in the number of fine light sources 9 depending upon the 
direction will generally cause directional variations of resolution of 
exposure apparatus, which is thus not preferable. 
It is conceivable in this case that the directional variations can be 
decreased by increasing the number of fine light sources, but the size of 
the curved surface mirrors constituting the fly's eye mirror must be 
decreased in order to increase the number of secondary light sources, 
which makes them hard to produce. 
If the reflection type optical integrator is composed of a plurality of 
fly's eye mirrors, the number of fine light sources in the meridional 
direction can be made equal to that in the sagittal direction. However, 
because the reflectivity of a reflecting mirror is low in the soft X-ray 
region, there occurs a problem that the overall X-ray reflectivity of the 
whole illumination optical system is considerably lowered where the 
plurality of fly's eye mirrors are used as the reflection type optical 
integrator. The throughput of the exposure apparatus also decreases 
thereby. 
As described above, there are problems with use of the fly's eye mirror. 
Then, in order to largely differentiate the divergent angle in the sagittal 
direction from that in the meridional direction, the reflection type 
optical integrator can be constructed in such an arrangement that two or 
more reflecting mirrors, in each of which a plurality of cylindrical 
mirrors are integrally aligned, for example as shown in FIG. 14, are set 
perpendicular to each other as shown in FIG. 15, whereby the divergent 
angle in the sagittal direction can be made largely different from that in 
the meridional direction. 
Namely, when the integrator 4a and integrator 4b converge X-rays in the 
meridional direction and in the sagittal direction, respectively, and when 
their focus positions are arranged to fall on the light source image (or 
light source), the light source image (or light source) 1 is formed with 
different divergent angles between in the meridional direction and in the 
sagittal direction. 
Incidentally, as shown in FIG. 16 and FIG. 23, checking parallel beams in 
the sagittal direction (in directions on the plane of the drawing) as to 
X-rays 2 outgoing (output) from the light source image (or light source) 1 
formed by the optical integrator, and defining the diameter of parallel 
beams at an exit angle of 0.degree., 21 (in the case of FIG. 16) or 24 (in 
the case of FIG. 23), as P(0)=q, a diameter of parallel beams 23 at an 
exit angle of .theta. is given as P(.theta.)=q.multidot.cos.theta.. Thus, 
the beam diameter P(.theta.) in a direction on the plane of the drawing 
becomes smaller as the exit angle .theta. increases. 
Thus, the cross section of parallel beams 21, 24 at the exit angle of 
0.degree. becomes nearly circular as shown in FIG. 17A or FIG. 24A, 
whereas the cross section of parallel beams 23, 26 at the exit angle of 
.theta. becomes elliptic with the major axis of P(0) in the meridional 
direction and the minor axis of P(.theta.) in the sagittal direction, as 
shown in FIG. 17B or FIG. 24B. 
As a result, a converging state of the converging beams after the parallel 
beams 21, 24 at the exit angle of 0.degree. are subjected to the 
converging function by the special reflecting mirror 3 is such that the 
beams are converged in a circular cone spanning an always equal angle 
.theta. at converging point p.sub.1 in the arcuate illumination region BF 
formed on the illuminated surface; whereas, a converging state of the 
converging beams after the parallel beams 23, 26 at the exit angle of 
.theta. are subjected to the converging function by the special reflecting 
mirror 3 is such that the beams are converged in an elliptic cone to form 
a converging point p.sub.2 in the arcuate illumination region BF on the 
illuminated surface (FIG. 18 or FIG. 25). 
This results in a problem that the angle spanned by the converging beams at 
the converging point p.sub.2 in the radial direction R at the converging 
point p.sub.2 is equal to that of the converging beams of the above 
parallel beams 21, 24 whereas the angle spanned by the converging beams at 
the converging point p.sub.2 in the tangent direction T at the converging 
point p.sub.2 is smaller (cos.theta. times smaller) than that in the 
radial direction R at the converging point p.sub.2. This problem becomes 
especially significant for parallel beams outgoing at a greater exit angle 
.theta. in the sagittal direction. 
When an illuminated object is illuminated by such an illuminating apparatus 
to converge the parallel beams in different cross sections and when an 
image thereof is formed by an imaging apparatus, the resolution thereof 
generally becomes nonuniform in the image plane. This is caused because 
part of the illuminated object is illuminated under such a condition that 
it does not satisfy the numerical aperture required by the imaging optical 
system. 
In more detail, if a numerical aperture of illumination light in the 
portion which is illuminated by the parallel beams at the exit angle of 
0.degree. in the arcuate illumination region is set to be approximately 
equal to that of the imaging apparatus, a numerical aperture of 
illumination light in a portion illuminated by parallel beams at large 
exit angles in the arcuate illumination region becomes smaller than the 
numerical aperture of the imaging apparatus. This results in a problem 
that an image can be obtained only at a lower resolution in this portion. 
In order to avoid such a problem, the numerical aperture of illumination 
light in the portion illuminated by the parallel beams at largest exit 
angles in the arcuate illumination region may be set to be approximately 
equal to the numerical aperture of the imaging apparatus. In this case, 
the portion illuminated by the parallel beams at relatively small exit 
angles is illuminated under a larger numerical aperture than the numerical 
aperture of the imaging apparatus, but excessive illumination light can be 
removed by a slit or the like provided in the imaging apparatus. An image 
with a uniform resolution can be attained accordingly by illuminating the 
illuminated object by such an illuminating apparatus. 
Incidentally, when the illuminated object is illuminated by the above 
illuminating apparatus, the diameter of beams 23 contributing to image 
formation out of the parallel beams 26 of the exit angle .theta. (beam 
diameter p(.theta.)) becomes p.sub.1 (.theta.) (equal to p(.phi.)) as 
shown in FIG. 26, which is smaller than the beam diameter p(.theta.) of 
the parallel beams 26. This means that X-rays outside the beam diameter 
p.sub.1 (.theta.) are eliminated by the imaging apparatus. 
If the optical integrator has a uniform reflectivity, the X-ray intensity 
of each parallel beams of the beams diameter p.sub.1 (.theta.), which are 
beams of substantial illumination light, differs depending upon .theta., 
because the X-ray intensity of the parallel beams of the beam diameter 
p(.theta.) is constant. Namely, the illuminated surface is not illuminated 
in a substantially uniform intensity, thus causing illumination 
variations. 
As described above, the arrangement using two or more reflecting mirrors in 
each of which a plurality of cylindrical mirrors are aligned also has 
problems. 
SUMMARY OF THE INVENTION 
It is, therefore, a first object of the present invention to provide an 
illuminating apparatus which can be produced more easily than heretofore 
and which does not greatly lower the X-ray reflectivity, solving the 
problems caused in the use of the fly's eye mirror. 
It is a second object of the present invention to provide a 
high-performance illuminating apparatus which has a much higher 
illumination efficiency than heretofore and which can make the numerical 
aperture in the illumination region formed in an arcuate shape 
approximately uniform irrespective of an illumination position, solving 
the problems caused in the use of two or more reflecting mirrors in each 
of which a plurality of cylindrical mirrors as described above are 
aligned, and to provide an exposure apparatus provided with the 
illuminating apparatus. 
To achieve the objects, a first aspect of the present invention is an 
illuminating apparatus comprising, at least, a light source system for 
forming a light source image of a predetermined size, and a condensing 
optical system for condensing beams from the light source system to 
illuminate an illuminated object. 
The light source system has a light source portion for supplying parallel 
beams, and a reflection type optical integrator for forming a plurality of 
light source images from the parallel beams from the light source portion; 
the reflection type optical integrator is provided with a reflecting 
surface for effecting the critical illumination in the meridional 
direction of the condensing optical system and a reflecting surface for 
effecting the Kohler illumination in the sagittal direction thereof; 
the condensing optical system has a special reflecting mirror for 
converting the beams from the light source image into parallel beams to 
illuminate the illuminated object in an arcuate pattern; and 
the special reflecting mirror is constructed of a part of a parabolic-toric 
body of rotation obtained by rotating a parabola about a base axis normal 
to a symmetric axis of the parabola and passing through a position that is 
a predetermined distance along the symmetry axis of the parabola from the 
vertex of the parabola. 
Further, a second aspect of the present invention is an illuminating 
apparatus comprising, at least, light source system for forming a light 
source image of a predetermined size, and a condensing optical system for 
condensing beams from the light source system to illuminate an illuminated 
object. 
The light source system has a light source portion for supplying parallel 
beams, and a reflection type optical integrator for forming a plurality of 
light source images from the parallel beams from the light source portion; 
the reflection type optical integrator is so arranged that a plurality of 
cylindrical reflecting surfaces are continuously and integrally formed 
only in one direction, so that there are formed reflecting surfaces for 
effecting the critical illumination in the meridional direction of the 
condensing optical system and reflecting surfaces for effecting the Kohler 
illumination in the sagittal direction thereof; 
the condensing optical system has a special reflecting mirror for 
converting the beams from the light source image into parallel beams to 
illuminate the illuminated object in an arcuate pattern; and 
the special reflecting mirror is constructed of a part of a parabolic-toric 
body of rotation obtained by rotating a parabola about a base axis normal 
to a symmetric axis of the parabola and passing through a position that is 
a predetermined distance along the symmetry axis of the parabola from the 
vertex of the parabola. 
Further, a third aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the second aspect of the invention, an X-ray reflecting multilayer film is 
provided on the reflecting surfaces of the reflection type optical 
integrator and the special reflecting mirror. 
Further, a fourth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the third aspect of the invention, the X-ray reflecting multilayer film is 
formed from a lamination of a plurality of alternate layers of either one 
combination selected from combinations of molybdenum/silicon, 
molybdenum/silicon compound, ruthenium/silicon, ruthenium/silicon 
compound, rhodium/silicon, and rhodium/silicon compound. 
Further, a fifth aspect of the present invention is an illuminating 
apparatus comprising, at least, a light source system for forming a light 
source image of a predetermined size, and a condensing optical system for 
condensing beams from the light source system to illuminate an illuminated 
object. 
The light source system has a light source portion for supplying parallel 
beams, and an optical integrator provided with a reflecting region and a 
non-reflecting region, for forming a plurality of light source images from 
the parallel beams from the light source portion; 
the condensing optical system has a special reflecting mirror for 
converting the beams from the light source image into parallel beams to 
illuminate the illuminated object in an arcuate pattern; and 
the special reflecting mirror is constructed of a part of a parabolic-toric 
body of rotation obtained by rotating a parabola about a base axis normal 
to a symmetric axis of the parabola and passing through a position that is 
a predetermined distance along the symmetry axis of the parabola from the 
vertex of the parabola. 
Further, a sixth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the fifth aspect of invention, the reflecting region of the optical 
integrator is formed from an X-ray reflecting multilayer film. 
Further, a seventh aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the sixth aspect of the invention, the X-ray reflecting multilayer film is 
formed from a lamination of a plurality of alternate layers of either one 
combination selected from combinations of molybdenum/silicon, 
molybdenum/silicon compound, ruthenium/silicon, ruthenium/silicon 
compound, rhodium/silicon, and rhodium/silicon compound. 
Further, an eighth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the sixth aspect of the invention, the non-reflecting region of the 
optical integrator is formed from an X-ray absorbing film. 
Further, a ninth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the eighth aspect of the invention, the X-ray absorbing film is made of 
nickel, silver, cadmium, cobalt, copper, iron, indium, nickel, platinum, 
antimony, tin, tellurium, or zinc, or a substance containing either one as 
a main ingredient. 
Further, a tenth aspect of the present invention is an illuminating 
apparatus comprising, at least, a light source system for forming a light 
source image of a predetermined size, and a condensing optical system for 
condensing beams from the light source system to illuminate an illuminated 
object. 
The light source system has a light source portion for supplying parallel 
beams, and a reflection type optical integrator for forming a plurality of 
light source images from the parallel beams from the light source portion; 
the condensing optical system has a special reflecting mirror for 
converting the beams from the light source image into parallel beams to 
illuminate the illuminated object in an arcuate pattern; 
the special reflecting mirror is constructed of a part of a parabolic-toric 
body of rotation obtained by rotating a parabola about a base axis normal 
to a symmetric axis of the parabola and passing through a position a 
predetermined distance that is along the symmetry axis of the parabola 
from the vertex of the parabola; and 
a desired X-ray reflectivity distribution is provided in a reflecting 
surface of the optical integrator and/or the special reflecting mirror. 
Further, an eleventh aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the tenth aspect of the invention, the desired X-ray reflectivity 
distribution is provided so as to make a value of R.sub.1 
(.theta.).multidot.R.sub.2 (.theta.)/cos.theta. constant or nearly 
constant, where .theta. is an exit angle of X-rays outgoing from a 
reflecting surface of the optical integrator, R.sub.1 (.theta.) a 
reflectivity on the reflecting mirror in that case, and R.sub.2 (.theta.) 
a reflectivity when the X-rays outgoing at the exit angle .theta. from the 
reflecting surface are reflected by the special reflecting mirror. 
Further, a twelfth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
eleventh aspect of the invention, the desired X-ray reflectivity 
distribution is provided by forming an X-ray reflecting multilayer film 
having an in-plane distribution of period lengths, on the reflecting 
surface of the optical integrator and/or the special reflecting mirror. 
Further, a thirteenth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
eleventh aspect of the invention, the desired X-ray reflectivity 
distribution is provided by forming an X-ray reflecting multilayer film 
having an in-plane distribution of period numbers, on the reflecting 
surface of the optical integrator and/or the special reflecting mirror. 
Further, a fourteenth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the eleventh aspect of the invention, the desired X-ray reflectivity 
distribution is provided by forming an X-ray reflecting multilayer film 
and an X-ray absorbing film thereon having a film thickness distribution, 
on the reflecting surface of the optical integrator and/or the special 
reflecting mirror. 
Further, a fifteenth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the fourteenth aspect of the invention, the X-ray reflecting multilayer 
film is formed from a lamination of a plurality of alternate layers of one 
combination selected from combinations of molybdenum/silicon, 
molybdenum/silicon compound, ruthenium/silicon, ruthenium/silicon 
compound, rhodium/silicon, and rhodium/silicon compound. 
Further, a sixteenth aspect of the present invention is an illuminating 
apparatus arranged in such a manner that in the illuminating apparatus of 
the fourteenth aspect of the invention, the X-ray absorbing film is made 
of silicon, beryllium, zirconium, boron, carbon, or molybdenum, or a 
substance containing one as a main ingredient. 
FIG. 1 shows an optical system of illuminating apparatus (an example) 
according to the present invention (first to fourth aspects) and is a 
cross section in the meridional direction, of the light source portion 1', 
reflection type optical integrator 2, light source image (or light source) 
1, and special reflecting mirror (condensing optical system) 3. 
As shown in FIG. 5, the cross section in the meridional direction, of the 
special reflecting mirror 3 forms a part of parabola PA and the special 
reflecting mirror 3 is constructed of a part of a parabolic-toric body of 
rotation obtained by rotating the parabola about the base axis Ax.sub.1 
(the axis perpendicular to the symmetry axis Y) passing a position Y.sub.0 
apart a predetermined distance along the symmetry axis Y from the vertex 
O. Namely, as shown in FIG. 6, the special reflecting mirror 3 is formed 
in an arcuate shape constructed of a part of a belt region between two 
latitudes 31, 32 of the parabolic-toric body of rotation. 
The light source portion 1' supplies parallel beams or nearly parallel 
beams, which are incident to the reflection type optical integrator 2. The 
reflection type optical integrator 2 is provided with reflecting surfaces 
for effecting the critical illumination in the meridional direction and 
reflecting surfaces for effecting the Kohler illumination in the sagittal 
direction. 
This reflection type optical integrator 2 is so arranged, as shown in FIG. 
3A and FIG. 3B (the cross section-along d-d' in FIG. 3A), that, for 
example, cylindrical reflecting surfaces (an example of curved surface 
mirrors) are continuously and integrally formed only in one direction. 
Namely, the reflection type optical integrator 2 according to the present 
invention is simpler in structure than the conventional reflection type 
optical integrator using the fly's eye mirror. Further, the reflecting 
surfaces do not have to be made so small as in the fly's eye mirror in 
order to overcome the directional variations of resolution in the exposure 
apparatus. Therefore, the reflection type optical integrator 2 according 
to the present invention (the first to fourth aspects) is easy to produce. 
In addition, because the reflection type optical integrator 2 according to 
the present invention (the first to fourth aspects) includes a plurality 
of reflecting surfaces integrally formed, it has no such problem that the 
overall X-ray reflectivity of the entire illumination optical system is 
greatly lowered as in the case of using a plurality of fly's eye mirrors 
as the reflection type optical integrator. 
The reflection type optical integrator 2 converges or condenses the 
parallel beams incident thereto in linear patterns in the sagittal 
direction on the base axis Ax.sub.1. Therefore, the light source image (or 
light source) 1 consisting of an assemblage of linear light sources 9 is 
formed in the number corresponding to the number of the cylindrical 
reflecting surfaces (an example of curved surface mirrors) in the 
converged place (FIG. 3C). 
The beams from the light source image (or light source) 1 thus formed are 
reflected and converged by the special reflecting mirror 3, whereby the 
illuminated surface is illuminated in an arcuate pattern. 
The optical system of the illuminating apparatus according to the present 
invention (the first to fourth aspects) is described by reference to FIGS. 
2A and 2B. Although FIGS. 2A and 2B show a transmission type optical 
system in order to facilitate the description, the optical system is of 
the reflection type in fact. 
FIG. 2A shows a cross section in the meridional direction, of the optical 
system of the illuminating apparatus. X-rays diverging from the X-ray 
source 4 are converted into parallel beams by the reflecting mirror 5 etc. 
to enter the reflection type optical integrator (not shown). Here, because 
the reflection type optical integrator has no converging effect on the 
beams in the meridional direction, the parallel beams are output in 
parallel in the meridional direction from the reflection type optical 
integrator. 
The X-rays output in the meridional direction from the reflection type 
optical integrator are converged by the special reflecting mirror 3 to 
illuminate the illuminated surface BF. In this case, the parallel beams 
incident to the special reflecting mirror 3 are converged at a point on 
the illuminated surface BF. 
Namely, the X-rays diverging from a point on the X-ray source 4 are 
converged through the optical system at a point on the illuminated surface 
BF in the meridional direction (cross section). Therefore, the illuminated 
surface is illuminated under the critical illumination in the meridional 
direction (in the direction of the radius of the arc of the arcuate 
illuminated surface BF; in the direction parallel to the Ax.sub.0 axis) so 
as to satisfy the uniformity of the numerical aperture. 
The uniformity of intensity in the meridional direction will be disturbed 
if a spatial intensity distribution of the X-ray source 4 is not uniform. 
Nevertheless, because the mask and wafer are moved in one direction in the 
exposure apparatus, the non uniformity of intensity distribution will be 
overcome in the moving direction. In other words, the non uniformity of 
intensity distribution in the meridional direction can be overcome by 
making the moving direction coincident with the meridional direction. 
Therefore, fully satisfactory illumination is made by the critical 
illumination in the meridional direction of the illuminated surface BF. 
A width (meridional width) L.sub.1 of the illumination light on the 
illuminated surface BF is determined by a size L.sub.3 of the X-ray source 
4 and a magnification in the meridional direction, of the illumination 
optical system (FIG. 2A). In the case of a synchrotron radiation (SR) or 
laser plasma X-ray source (LPX), which are typical soft X-ray sources, the 
size of the radiation source is about 1 mm or less. Therefore, insofar as 
the magnification of the illumination optical system is not increased too 
much, the width L.sub.1 can be kept fully small and a spatial, optical 
loss can also be kept fully small. 
Next described referring to FIG. 2B is a state in the sagittal direction of 
the optical system of the illuminating apparatus according to the present 
invention (the first to fourth aspects). FIG. 2B shows a cross section in 
the sagittal direction, of the optical system of the illuminating 
apparatus. 
The X-rays diverging from the X-ray source 4 are converted into parallel 
beams by the reflecting mirror 5 to be incident on the reflection type 
optical integrator 2. Since the reflection type optical integrator 2 has 
the converging effect on the beams in the sagittal direction, it forms the 
light source image (or light source) composed of a plurality of fine light 
sources (linear light sources) 9 in the sagittal direction. This light 
source image (or light source) is an array of linear, fine light sources 9 
arranged in the sagittal direction, as shown in FIG. 3C. 
X-rays diverging in the sagittal direction from the light source image (or 
light source) consisting of the plurality of fine light sources (linear 
light sources) 9 are converted into parallel beams by the special 
reflecting mirror 3 to illuminate the illuminated surface BF. Namely, the 
illuminated surface BF is illuminated under the Kohler illumination in the 
sagittal direction so that the both uniformities of the numerical aperture 
and the illumination intensity are satisfied simultaneously. 
The reflecting surfaces constituting the reflection type optical integrator 
according to the present invention (the first to fourth aspects) may be 
either concave surfaces or convex surfaces. When the reflecting surfaces 
are concave surfaces, the light source image (or light source) 1 is formed 
on the output side of the reflecting surfaces. Therefore, the light source 
image (or light source) 1 can be formed on the base axis Ax.sub.1 by 
placing the reflection type optical integrator 2 on the left side of the 
base axis Ax.sub.1 on the plane of FIG. 1. When the reflecting surfaces 
are convex surfaces, the light source image (or light source) 1 is formed 
on the opposite side to the output side of the reflective surfaces. 
Therefore, the light source image (or light source) 1 can be formed on the 
base axis Ax.sub.1 by placing the reflection type optical integrator 2 on 
the right side of the base axis Ax.sub.1 on the plane of FIG. 1. 
It is preferred that the reflective surfaces of the reflection type optical 
integrator and the special reflecting mirror according to the present 
invention (the first to third aspects) be formed from an X-ray reflecting 
multilayer film (the fourth aspect). The X-ray reflecting multilayer film 
is preferably formed from a lamination of a plurality of alternate layers 
of one combination selected from combinations of molybdenum/silicon, 
molybdenum/silicon compound, ruthenium/silicon, ruthenium/silicon 
compound, rhodium/silicon, and rhodium/silicon compound (this arrangement 
is particularly preferable in the case of X-rays with a wavelength of 
about 13 nm). 
As described above, the reflection type optical integrator according to the 
present invention (the first to fourth aspects) is easier to produce than 
the conventional integrators and free of a great decrease in X-ray 
reflectivity. 
With the illuminating apparatus provided with such a reflection type 
optical integrator, the illuminated surface is illuminated under the 
critical illumination in the meridional direction while satisfying the 
uniformity of numerical aperture. Further, the illuminated surface is 
illuminated under the Kohler illumination in the sagittal direction while 
simultaneously satisfying the uniformities of numerical aperture and 
illumination intensity. 
Namely, the illuminated surface can be illuminated in an arcuate pattern 
with uniform intensity by the illuminating apparatus (the first to fourth 
aspects) of the present invention. Thus, the exposure apparatus provided 
with the illuminating apparatus of the present invention (the first to 
fourth aspects) can obtain an image with uniform exposure over the entire 
arcuate surface as the illuminated surface, so that a pattern on the mask 
located on the illuminated surface can be accurately transferred with high 
throughput onto the substrate. 
As shown in FIG. 5, the cross section in the meridional direction, of the 
special reflecting mirror 3 according to the present invention (the fifth 
to ninth aspects) is a part of parabola PA, and this special reflecting 
mirror 3 consists of a part of a parabolic-toric body of rotation obtained 
by rotating the parabola about the base axis Ax.sub.1 (an axis 
perpendicular to the symmetry axis Y) passing a position Y.sub.0 apart a 
predetermined distance along the symmetry axis Y from the vertex O. 
Namely, as shown in FIG. 6, the special reflecting mirror 3 has an arcuate 
shape composed of a part of a belt region between two latitudes 31, 32 of 
the parabolic-toric body of rotation. 
FIG. 10 shows an example of the illuminating apparatus according to the 
present invention (the fifth to ninth aspects) and is a partial cross 
section in the sagittal direction, of the light source image (or light 
source) 1 and the special reflecting mirror (an example of the condensing 
optical system) 3. Here, parallel beams 21, 22, 23 outgoing (output) from 
the light source image (or light source) 1 are arranged so that beam 
diameters thereof all become equal to (or approximately equal to) each 
other. In detail, when output from a portion of the light source image (or 
light source) where the sagittal width is q(0), in the light source image 
(or light source) 1, the parallel beams 21 at the exit angle of 0.degree. 
form a bundle of beams of a width p(0). 
Also, when output from a portion of the light source image (or light 
source) where the sagittal width is q(.phi.), in the light source image 
(or light source) 1, the parallel beams 23 outgoing at an angle .phi. form 
a bundle of beams of a width p(.phi.). 
Further, when output from a portion of the light source image (or light 
source) where the sagittal width is q(.theta.), in the light source image 
(or light source) 1, the parallel beams 22 outgoing at an angle .theta. 
form a bundle of beams of a width p(.theta.). 
Then the sagittal widths q(0), q(.theta.), q(.phi.) of the portions of the 
light source image (or light source) are determined so that the widths of 
the parallel beams p(0), p(.theta.), p(.phi.) become equal (or 
approximately equal) to each other. 
The following describes the light source image (or light source) 1 
satisfying the above condition. First, point light sources located between 
the center 0 of the light source image (or light source) 1 and a point 
S.sub.2 located at a distance of q(0)/2 in the sagittal direction from the 
center 0 emit light (for example, X-rays etc.) with a diverging angle 
2.phi.. Point light sources outside it, i.e., between the point S.sub.2 
and a point S.sub.1 at a distance of q(.phi.)/2 in the sagittal direction 
from the center 0 of the light source image (or light source), emit light 
(for example, X-rays etc.) with an angle between the exit angle .theta. 
and the exit angle .phi., where .theta. is an arbitrary angle satisfying 
0&lt;.theta.&lt;.phi.. 
The illuminating apparatus according to the present invention (the fifth to 
ninth aspects) is further described in more detail using the partial cross 
section of the optical integrator (an example of the optical integrator 
according to the present aspects) of FIG. 11. FIG. 11 shows a partial 
cross section in the sagittal plane, of the optical integrator 4. 
FIG. 11 shows only a half of the optical integrator 4, assuming the optical 
integrator 4 is symmetric with respect to the symmetry axis A.sub.0. 
Further, FIG. 11 shows only some of a plurality of curved surface 
reflecting mirrors (hereinafter referred to as curved surface mirrors) 
constituting the optical integrator 4 in order to facilitate the 
description. Namely, actual applications often include a lot of curved 
surface mirrors adjacent to each other. 
When the curved surface mirrors are convex surfaces as shown in FIG. 11, 
the light source image (or light source, not shown) is formed on the left 
side of the reflecting surfaces on the plane of the drawing. Conversely, 
if they are concave surfaces, the light source image (or light source, not 
shown) is formed on the right side of the reflecting surfaces on the plane 
of the drawing. 
A curved surface mirror 41 is located on the symmetry axis A.sub.0 of the 
optical integrator 4 and light (for example, X-rays etc.) incident to the 
curved surface mirror is outgoing as divergent light with divergent angle 
2.phi.. Similarly, in the case of a curved surface mirror 42 located at 
q(0)/2 from the symmetry axis A.sub.0, incident light (for example, X-rays 
etc.) is outgoing as divergent light with divergent angle 2.phi., as in 
the case of the curved surface mirror 41. On the other hand, in the case 
of a curved surface mirror 44 located at q(.phi.)/2 from the symmetry axis 
A.sub.0, light (for example, X-rays etc.) is reflected only at an exit 
angle .phi., but is not reflected at other angles. Further, a curved 
surface mirror 43 between the curved surface mirror 42 and the curved 
surface mirror 44 reflects the light (for example, X-rays etc.) at angles 
only between the exit angles .theta. and .phi.. 
The curved surface mirror 43 is further described in more detail using FIG. 
12. FIG. 12 is a cross section in the sagittal plane, of the curved 
surface mirror 43. On the surface of the curved surface mirror 43 there 
are a reflecting region (reflecting portion) 5 for reflecting the light 
(for example, X-rays etc.) and a non-reflecting region (non-reflecting 
portion) 6 that does not reflect the light. 
For example, in the case where the light is X-rays, the non-reflecting 
region 6 may be provided in such a manner that the multilayer film is not 
formed there on the surface of the curved surface mirror so as not to 
reflect the X-rays (or that the multilayer film is removed), or in such a 
manner that an absorbing member 7 made of a substance that is liable to 
absorb the X-rays is formed on the surface of the multilayer film, as 
shown in FIG. 12. 
The angle .theta. is determined by the magnitude of width m of the 
absorbing member 7, and there is a relation of formula (1) between .theta. 
and m, when a radius of curvature of a reflecting surface of a curved 
surface mirror is r. 
EQU m=2r.multidot.sin(.theta./2) (1) 
Namely, adjusting the width m of the absorbing member 7, .theta. can be set 
at an arbitrary value between 0 and .phi.. 
In order to keep P(.theta.) in FIG. 10 always constant in the range of 
0&lt;.theta.&lt;.phi., the relation of formula (2) should hold. 
EQU q(0)=q(.phi.).multidot.cos.phi.=q(.theta.).multidot.cos.theta.(2) 
From this formula (2), the following formula (3) is obtained. 
EQU cos.theta.=q(0)/q(.theta.)=q(0)/{q(0)+2x} (3) 
In the formula, x represents a distance x shown in FIG. 11. 
Therefore, in the curved surface mirror 43 shown in FIG. 11, P(.theta.) 
becomes always constant when .theta. satisfies the relation of formula (4) 
with respect to the distance x, and its value is q(0). 
EQU .theta.=cos.sup.-1 q(0)/{q(0)+2x}! (4) 
Further, to obtain such .theta., the width m of the absorbing member 7 
should be set at the value given by formula (1). 
Using such an optical integrator, parallel beams having the same cross 
section are emitted at respective exit angles from the light source image 
(or light source). Accordingly, the illuminating apparatus according to 
the present invention can illuminate the illuminated surface with a same 
numerical aperture at any position without increasing the number of 
reflecting mirrors (or without lowering a quantity of X-rays) as compared 
with the conventional illuminating apparatus. Namely, it can illuminate 
the illuminated surface in the arcuate pattern with a uniform numerical 
aperture while maintaining the telecentricity under the Kohler 
illumination. 
In order to keep the reflectivity high, the X-ray reflecting multilayer 
film is preferably formed from a lamination of a plurality of alternate 
layers of one combination selected from combinations of 
molybdenum/silicon, molybdenum/silicon compound, ruthenium/silicon, 
ruthenium/silicon compound, rhodium/silicon, and rhodium/silicon compound 
(this arrangement is particularly preferable when the X-rays of a 
wavelength of 13 nm are used). 
Further, the X-ray absorbing film is preferably made of a substance with 
high absorptance to the X-rays used. For example, the X-ray absorbing film 
is preferably made of nickel (particularly preferable), silver, cadmium, 
cobalt, copper, iron, indium, nickel, platinum, antimony, tin, tellurium, 
or zinc, or a substance containing one of them as a main ingredient (this 
is particularly preferable when the X-rays of a wavelength of 13 nm are 
used). 
The reflecting curved surfaces constituting the optical integrator may be 
constructed of the fly's eye mirror as well as the cylindrical mirrors. 
As described above, the illuminating apparatus of the present invention 
(the fifth to ninth aspects) can illuminate the illuminated surface in the 
arcuate pattern with a uniform numerical aperture while maintaining the 
telecentricity under the Kohler illumination. Therefore, exposure 
apparatus provided with the illuminating apparatus of the present 
invention (the fifth to ninth aspects) can obtain an image in a uniform 
resolution over the entire arcuate surface as the illuminated surface, so 
that the pattern on the mask located at the illuminated surface can be 
accurately transferred onto the substrate with high throughput. 
FIG. 19 shows an optical system (an example) of the illuminating apparatus 
according to the present invention (the tenth to sixteenth aspects) and is 
a perspective view of the light source image (or light source) 1, the 
condensing optical system consisting of the special reflecting mirror 3, 
and the arcuate illumination region BF. 
As shown in FIG. 5, the cross section in the meridional direction, of the 
special reflecting mirror 3 is a part of parabola PA and this special 
reflecting mirror 3 is constructed of a part of a parabolic-toric body of 
rotation obtained by rotating the parabola about the base axis Ax.sub.1 
(an axis perpendicular to the symmetry axis Y) passing through the 
position Y.sub.0 that is a predetermined distance along the symmetry axis 
Y from the vertex O. Namely, as shown in FIG. 6, the special reflecting 
mirror 3 is formed in an arcuate shape, which is a part of a belt region 
between two latitudes 31, 32 of the parabolic-toric body of rotation. 
Parallel beams 21a, 22a, 23a output (outgoing) from the light source image 
(or light source) 1 and contributing to image formation are reflected by 
the special reflecting mirror 3 to become converging beams 21b, 22b, 23b 
to be converged at points p.sub.1, p.sub.2, p.sub.3 on the arcuate 
illumination region BF. In this case, the parallel beams 21a, 22a, 23a 
contributing to image formation are equal in beam diameter to each other, 
and the converging beams 21b, 22b, 23b contributing to image formation are 
equal in X-ray intensity to each other. 
Namely, in the case of the illuminating apparatus according to the present 
invention (the tenth to sixteenth aspects), for example, the reflecting 
surfaces of the optical integrator and/or the special reflecting mirror 
are provided with a desired X-ray reflectivity distribution so that X-ray 
intensities of the converging beams 21b, 22b, 23b become equal to each 
other. 
In other words, using the optical integrator and/or special reflecting 
mirror having the desired X-ray reflectivity distribution, the 
illuminating apparatus according to the present invention (the tenth to 
sixteenth aspects), can illuminate the illumination region with a 
sufficient numerical aperture, independent of an illuminated position, and 
further with a uniform intensity. Namely, the illuminated surface can be 
illuminated in the arcuate pattern with a uniform intensity while 
maintaining the telecentricity under the Kohler illumination. 
The desired X-ray reflectivity distribution can be realized, for example, 
by setting the value of R.sub.1 (.theta.).multidot.R.sub.2 
(.theta.)/cos.theta. constant or approximately constant. 
The X-ray intensities of converging beams 21b, 22b, 23b are determined, for 
example as shown in FIG. 20 (wherein the optical integrator 4 is enlarged 
and a part thereof is shown in order to facilitate the description), by 
the reflectivity R.sub.1 (.theta.) on a curved surface reflecting mirror 
41, of X-rays 2 output at an exit angle .theta. from the curved surface 
reflecting mirror 41 forming the optical integrator 4, and the 
reflectivity R.sub.2 (.theta.) when the X-rays 2 output at the exit angle 
.theta. from the curved surface reflecting mirror 41 are reflected by the 
special reflecting mirror 3. 
A basic method for setting the reflectivities R.sub.1 (.theta.), R.sub.2 
(.theta.) is described in the following. An intensity I(.theta.) at each 
exit angle, of parallel beams 26 emitted from the light source image (or 
light source) 1 is expressed by formula (1) when an intensity of parallel 
beams 24 at the exit angle of 0.degree. is I(0). 
EQU I(.theta.)=I(0).multidot.R.sub.1 (.theta.)/R.sub.1 (0) (1) 
I(.theta.) is an intensity of the beams 26, and an intensity I.sub.1 
(.theta.) of substantial beams 23a is given by formula (2). 
EQU I.sub.1 (.theta.)=I(.theta.).multidot.cos.phi./cos.theta. (2) 
On the other hand, an intensity I.sub.2 (.theta.) of beams 23b incident to 
the illuminated surface is given by formula (3). 
EQU I.sub.2 (.theta.)=I.sub.1 (.theta.).multidot.R.sub.2 
(.theta.)=I(0).multidot.R.sub.1 (.theta.).multidot.R.sub.2 
(.theta.).multidot.cos.phi./{R.sub.1 (0).multidot.cos.theta.}(3) 
Accordingly, in order to make uniform (or nearly uniform) the intensity 
I.sub.2 (.theta.) of beams incident to the illuminated surface, a 
combination may be selected so that the value of R.sub.1 
(.theta.).multidot.R.sub.2 (.theta.)/cos.theta. becomes constant (or 
nearly constant) against the exit angle .theta.. 
If there remains illumination variations in spite of the illumination 
effected under the above condition (for example, if aberrations of the 
illumination optical system cause the illumination variations), correction 
may be well effected based on formula (3) so as to make the illumination 
intensity I.sub.2 (.theta.) uniform (or nearly uniform). 
As described above, the illuminating apparatus according to the present 
invention (the tenth to sixteenth aspects) can illuminate the illuminated 
object in a uniform (or nearly uniform) manner, overcoming the 
illumination variations (including those due to unknown causes) due to 
causes other than the substantial change of beam diameter depending upon 
the exit angle .theta.. 
Further, in cases where restrictions from fabrication of optical elements 
determine a distribution of either R.sub.1 (.theta.) or R.sub.2 (.theta.), 
the correction is possible by adjusting the other. Namely, the correction 
is possible by adjusting either one of the optical integrator and the 
special reflecting mirror. 
The desired X-ray reflectivity distribution can be given to the reflecting 
surface of the optical integrator and/or the special reflecting mirror by 
providing an X-ray reflecting multilayer film having an in-plane 
distribution of period lengths in the reflecting surface. In other words, 
because the X-ray reflectivity changes depending upon the period length of 
the multilayer film, a desired distribution of reflectivities can be made 
by forming a distribution of period lengths in a reflecting surface. 
The X-ray reflectivity distribution can also be realized by providing an 
X-ray reflecting multilayer film having an in-plane distribution of period 
numbers in the reflecting surface. In other words, because the X-ray 
reflectivity changes depending upon the period number of the multilayer 
film, a desired distribution of reflectivities can be given by forming a 
distribution of period numbers in a reflecting surface. 
Further, the X-ray reflectivity distribution can also be realized by 
providing an X-ray reflecting multilayer film and an X-ray absorbing film 
thereon having a distribution of film thicknesses on a reflecting surface. 
In order to keep the reflectivity high the X-ray reflecting multilayer film 
is preferably formed from a lamination of a plurality of alternate layers 
of one combination selected from combinations of molybdenum/silicon, 
molybdenum/silicon compound, ruthenium/silicon, ruthenium/silicon 
compound, rhodium/silicon, and rhodium/silicon compound (this arrangement 
is particularly preferable in the cases of use of the X-rays of wavelength 
13 nm). 
Further, the X-ray absorbing film may be made of any substance that can 
absorb the X-rays used, and it is preferably made of a substance that can 
readily control the X-ray transmittance by changing the film thickness. 
For example, the X-ray absorbing film is preferably made of silicon, 
beryllium, zirconium, boron, carbon, or molybdenum, each having a 
relatively low X-ray absorptance, or a substance containing one of them as 
a main ingredient (this arrangement is particularly preferable in the 
cases of use of the X-rays of wavelength 13 nm). 
When the X-ray absorbing film is made of one of these substances, the film 
thickness control for obtaining a desired transmittance distribution 
(eventually, for obtaining a desired reflectivity distribution) becomes 
easier. Since the X-ray transmittance can also be readily controlled by 
changing the film thickness of either one of the above materials suitable 
for the X-ray reflecting multilayer film, the X-ray absorbing film may be 
made of either one of these materials. 
The reflecting curved surfaces constituting the optical integrator may be 
constructed of the fly's eye mirror in addition to the cylindrical 
mirrors. 
As described above, the illuminating apparatus of the present invention 
(the tenth to sixteenth aspects) can illuminate the illuminated object in 
the arcuate pattern with a uniform numerical aperture while maintaining 
the telecentricity under the Kohler illumination. Therefore, exposure 
apparatus provided with the illuminating apparatus of the present 
invention (the tenth to sixteenth aspects) can obtain an image in a 
uniform resolution over the entire arcuate surface as the illuminated 
surface, so that the pattern on the mask located at the illuminated 
surface can be accurately transferred with high throughput onto the 
substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Embodiment 1 
The illuminating apparatus of the present embodiment is composed of an 
optical system having the light source portion 1' and the reflection type 
optical integrator 2, and the parabolic-toric surface mirror (an example 
of the condensing optical system) 3 being the special reflecting mirror 
consisting of a part of the parabolic-toric body of rotation (FIG. 1). 
As shown in FIG. 5, the cross section in the meridional direction, of the 
special reflecting mirror 3 is a part of parabola PA and this special 
reflecting mirror 3 is constructed of a part of a parabolic-toric body of 
rotation obtained by rotating the parabola about the base axis Ax.sub.1 
(an axis perpendicular to the symmetry axis Y) passing through the 
position Y.sub.0 apart a predetermined distance along the symmetry axis Y 
from the vertex O. Namely, as shown in FIG. 6, the special reflecting 
mirror 3 has an arcuate shape composed of a part of a belt region between 
two latitudes 31, 32 of the parabolic-toric body of rotation. 
The light source portion 1' supplies parallel beams or nearly parallel 
beams, and the beams are incident on the reflection type optical 
integrator 2. The optical integrator 2 is constructed in such a manner 
that cylindrical reflecting surfaces (an example of curved surface 
mirrors) are continuously and integrally formed only in one direction, as 
shown in FIG. 3A and FIG. 3B (a cross section along d-d' in FIG. 3A). 
Namely, the reflection type optical integrator 2 of the present embodiment 
is simpler in structure than the conventional reflection type optical 
integrator using the fly's eye mirror. It is not necessary to form small 
reflecting surfaces as in the fly's eye mirror in order to overcome the 
directional variations of resolution in the exposure apparatus. Therefore, 
the reflection type optical integrator 2 of the present embodiment is 
easier to produce. 
Since the reflection type optical integrator 2 of the present embodiment is 
composed of a plurality of reflecting surfaces integrally formed, the X-ray 
reflectivity of the total illumination optical system is free of a great 
decrease as observed when a plurality of fly's eye mirrors are used as the 
reflection type optical integrator. 
This reflection type optical integrator 2 converges the parallel beams 
incident thereto in linear patterns in the sagittal direction on the base 
axis Ax.sub.1. Therefore, formed at a converging place is the light source 
image (or light source) 1 consisting of an assemblage of linear light 
sources 9 in the number corresponding to the number of the cylindrical 
reflecting surfaces (an example of curved surface mirrors) (FIG. 3C). 
Beams from the light source image (or light source) 1 thus formed are 
reflected and converged by the special reflecting mirror 3 to illuminate 
the illuminated surface in an arcuate pattern. The illuminated surface is 
illuminated under the critical illumination in the meridional direction 
(in the direction of the radius of the arc of the arcuate illuminated 
surface BF; in the direction parallel to the Ax.sub.0 axis) so as to 
satisfy the uniformity of numerical aperture. Further, the illuminated 
surface BF is illuminated under the Kohler illumination in the sagittal 
direction while satisfying the uniformities of numerical aperture and 
illumination intensity simultaneously. 
FIG. 4 is an explanatory drawing to show the structure and layout of the 
illuminating apparatus of the present embodiment, and an exposure 
apparatus (an example) provided with the illuminating apparatus. 
The light source portion is composed of a laser plasma X-ray source 41 and 
a paraboloidal mirror 51. The laser plasma X-ray source 41 is a point 
light source having the light source size of about 100 .mu.m, from which 
X-rays diverge nearly isotropically. When the paraboloidal mirror 51 
reflects the diverging beams, the X-rays diverging from the laser plasma 
X-ray source 41 are converted into parallel beams in a desired cross 
section. By this, parallel beams or nearly parallel beams with high 
intensity are supplied. The beams are incident to the reflection type 
optical integrator 2. 
It is noted that the system for supplying the parallel beams should not be 
limited to the combination of the light source with the curved surface 
mirror such as the paraboloidal mirror, as described above. For example, 
when the light source is one emitting nearly parallel beams such as the 
synchrotron radiation source, the radiation can be directly guided from 
the light source to the reflection optical integrator 2. 
When the laser plasma X-ray source is used, nearly parallel beams can be 
directly guided from the light source to the optical integrator 2 without 
using the paraboloidal mirror if the laser plasma X-ray source is set 
fully away from the integrator 2. However, the arrangement of the present 
embodiment is preferred in that case, because the spatial utility factor 
or efficiency of light becomes much higher. 
As described, the light source portion supplies the parallel beams or 
nearly parallel beams, and the beams are incident on the reflection type 
optical integrator 2. X-rays outgoing from the reflection type optical 
integrator 2 are reflected by the special reflecting mirror 3 to 
illuminate the mask 6 in an arcuate pattern. 
In this case, the width of the arcuate illuminated surface (the width in 
the meridional direction) was set smaller than the width from which a good 
image was obtained through the imaging apparatus 7. The illuminated surface 
(mask surface) was illuminated under the critical illumination in the 
meridional direction so as to satisfy the uniformity of numerical 
aperture. Also, the illuminated surface was illuminated under the Kohler 
illumination in the sagittal direction so as to satisfy the uniformities 
of numerical aperture and illumination intensity at a time. 
The magnification in the meridional direction, of the illumination optical 
system of the illuminating apparatus (the magnification of the critical 
illumination optical system) was 20. Since the light source size of the 
laser plasma X-ray source was about 100 .mu.m, the width of the 
illumination region (arcuate pattern) on the mask as the illuminated 
surface (the meridional width) was about 2 mm. 
Since the width for obtaining a good image was about 2 mm for the imaging 
apparatus 7 in the present embodiment, most illumination light was guided 
into the imaging optical system of the imaging apparatus to contribute to 
image formation. In the imaging apparatus 7, the light that illuminates 
regions except for the region for obtaining a good image needs to be 
removed for example by a slit or the like (not shown). However, in the 
case of the present embodiment, the light (X-rays) to be removed by the 
slit or the like was extremely little, because the width of the 
illumination region (arcuate pattern) on the mask as the illuminated 
surface (the meridional width) was approximately equal (about 2 mm) to the 
width for obtaining a good image through the imaging apparatus 7. 
Therefore, the spatial utility factor of X-rays is high in the present 
embodiment. 
X-rays transmitted by the mask 6 were guided through the imaging apparatus 
7 of the magnification 1/4 to be irradiated onto the substrate 8. On this 
occasion, the pattern on the mask 6 was transferred onto the substrate 8. 
In the present embodiment the substrate was a silicon wafer and a 
photoresist laid on the surface thereof was exposed to X-rays. In this 
state, moving the mask 6 and substrate 8 in the directions of the arrows 
shown in FIG. 4, the pattern on the entire surface of mask was transferred 
onto the substrate. 
In the present embodiment, the frequency of pulse emission of the laser 
plasma X-ray source was 500 Hz and the moving speed of mask was 24 mm/sec. 
Since the width in the moving direction, of the illumination light (the 
meridional width) is about 2 mm, each point on the mask is illuminated by 
about 40 pulses of X-rays by scanning. Since the laser plasma X-ray source 
is not always uniform in spatial and temporal intensity distributions, the 
X-ray intensity of each pulse is not constant. However, because each point 
on the mask is illuminated by a lot of pulses upon scanning as described 
above, an integral value thereof is constant at each point on the mask, 
thereby enabling it to be illuminated it with uniform intensity. 
As a result, patterns with a minimum pattern size of 0.1 .mu.m were 
obtained throughout a large area (about 10 cm.sup.2) on the substrate by 
scanning the arcuate exposure region of length 30 mm by about 35 mm on the 
substrate. The fact that such fine patterns were obtained in a large area 
shows that the illuminating apparatus of the present invention has 
sufficient performance as the illuminating apparatus for the exposure 
apparatus. Further, because of the capability of exposure over a large 
area, the throughput of the exposure apparatus was greatly improved. 
If the synchrotron radiation source is used as the system for supplying the 
parallel beams, the width of illumination light (the meridional width) 
becomes smaller, because the magnification of the critical illumination 
optical system in the meridional direction of the illuminating apparatus 
becomes considerably smaller than 1; but no exposure variations appear in 
the scanning direction because the synchrotron radiation source is a 
continuously emitting source. 
Although in the present embodiment the magnification of the critical 
illumination optical system in the meridional direction of the 
illuminating apparatus was 20, the present invention is not limited to it. 
For example, the magnification may be set larger than it. In that case, the 
light-source-side numerical aperture becomes large in the meridional cross 
section, so that in the case of a diverging light source such as the laser 
plasma X-ray source, diverging X-rays can be taken in at a large solid 
angle into the illuminating apparatus, thereby increasing the intensity of 
illumination light. 
The present embodiment employed the slit in the illuminating apparatus, but 
the slit may be omitted if the width of the arc of the arcuate illumination 
region (the meridional width) is set sufficiently smaller than the width 
for obtaining a good image by the imaging apparatus. The width of the arc 
can be easily set by adjusting the magnification of the illumination 
optical system. 
The reflection type optical integrator of the present embodiment is easier 
to produce than the conventional ones and has no great decrease of X-ray 
reflectivity. 
With the illuminating apparatus provided with such a reflection type 
optical integrator, the illuminated surface was illuminated under the 
critical illumination in the meridional direction so as to satisfy the 
uniformity of numerical aperture. Further, the illuminated surface was 
illuminated under the Kohler illumination in the sagittal direction so as 
to satisfy the uniformities of numerical aperture and illumination 
intensity at a simultaneously. 
Namely, the illuminating apparatus of the present embodiment was able to 
illuminate the illuminated surface in the arcuate pattern with uniform 
intensity. Therefore, an exposure apparatus provided with the illuminating 
apparatus of the present embodiment was able to obtain an image with 
uniform exposure over the entire arcuate surface as the illuminated 
surface, so that the pattern on the mask located on the illuminated 
surface was able to be accurately transferred with high throughput onto 
the substrate. 
The present embodiment used the transmission type mask as the mask, but the 
same effects were also achieved using a reflection type mask. 
In the present embodiment, the wavelength of X-rays was 13 nm, and the 
reflective surfaces of the reflection type optical integrator and special 
reflecting mirror were coated with an X-ray reflecting multilayer film (a 
lamination of a plurality of alternate layers of molybdenum and silicon) 
for improving the reflectivity. 
Embodiment 2 
FIG. 13 is an explanatory drawing to show the structure and layout of the 
illuminating apparatus of the present embodiment, and an exposure 
apparatus (an example) provided with the illuminating apparatus. 
The illuminating apparatus of the present embodiment is composed of a light 
source system having a light source portion 8 and reflection type optical 
integrators 4a, 4b, and a parabolic-toric mirror (an example of condensing 
optical system) 3 which is the special reflecting mirror composed of a 
parabolic-toric body of rotation. 
As shown in FIG. 5, the cross section in the meridional direction, of the 
special reflecting mirror 3 according to the present invention is a part 
of parabola PA, and this special reflecting mirror 3 is constructed of a 
part of a parabolic-toric body of rotation obtained by rotating the 
parabola about the base axis Ax.sub.1 (an axis perpendicular to the 
symmetry axis Y) passing through the position Y.sub.0 that is a 
predetermined distance along the symmetry axis Y from the vertex O. 
Namely, as shown in FIG. 6, the special reflecting mirror 3 has an arcuate 
shape composed of a part of a belt region between two latitudes 31, 32 of 
the parabolic-toric body of rotation. 
The light source portion 8 is composed of a laser plasma X-ray source 81 
and a paraboloidal mirror 82. The laser plasma X-ray source 81 is a point 
light source having the light source size of about 100 .mu.m, from which 
X-rays diverge nearly isotropically. Reflecting the diverging light by the 
paraboloidal mirror 82, the X-rays diverging from the laser plasma X-ray 
source 81 can be converted into parallel beams in a desired cross section. 
By this, parallel beams or nearly parallel beams with high intensity are 
supplied. The beams are incident to the reflection type optical integrator 
4a. 
It is noted that the system for supplying the parallel beams is not limited 
to the combination of the light source with the curved surface mirror such 
as the paraboloidal mirror as described above. For example, if the light 
source is one emitting nearly parallel beams such as the synchrotron 
radiation source, the beams may be directly guided from the light source 
to the reflection type optical integrator 4a. 
If the laser plasma X-ray source is used, nearly parallel beams can be 
guided directly from the light source to the integrator 4a without using 
the paraboloidal mirror but by placing the laser plasma X-ray source fully 
away from the integrator 4a. However, the arrangement of the present 
embodiment is preferred also in that case, because the spatial utility 
factor of light becomes much higher. 
As described, the light source portion 8 supplies the parallel beams or 
nearly parallel beams, the beams are incident on the reflection type 
optical integrator 4a, and further, beams reflected thereby are incident 
on the reflection type optical integrator 4b. 
The reflection type optical integrator 4a is composed of an assemblage of 
cylindrical mirrors having a plurality of concave surfaces as shown in 
FIG. 14A, and converges parallel beams incident thereon in the meridional 
direction. The reflection type optical integrator 4b is composed of an 
assemblage of cylindrical mirrors having a plurality of a convex surfaces 
as shown in FIG. 14B, and converges parallel beams incident thereon in the 
sagittal direction. 
For example, when the diameter t.sub.1 (FIG. 11) of the cylindrical mirrors 
constituting the reflection type optical integrator 4b is about 22 .mu.m 
and the height t.sub.2 about 1.5 .mu.m, a divergent angle thereof 2.phi. 
is about 60.degree.. 
The reflection type optical integrator 4b is provided, as shown in FIG. 12, 
with a non-reflecting region (non-reflecting portion) 6 on the reflecting 
surfaces. In the present embodiment, this non-reflecting region 6 was 
formed from an X-ray absorbing member (a layer of nickel film in the film 
thickness of about 40 nm) 7. When the wavelength of X-rays was 13 nm, the 
reflectivity by the absorbing member was decreased to one hundredth or 
less of the reflectivity by the reflecting surfaces. 
In the present embodiment the absorbing member was formed by the lift-off 
process. In more detail, a desired resist pattern was formed over the 
surface of the reflection type optical integrator 4b, a mask pattern was 
formed in regions except for surface regions where the absorbing member 
was to be formed, and a thin film of the absorbing member was formed by a 
vacuum thin film forming method such as the vapor deposition or sputtering 
method. Then, removing the resist and the thin film laid on the resist, for 
example, with a solvent, the absorbing member was formed in desired 
patterns. 
The resist pattern was able to be produced as a very precise pattern using 
the stepper or the like. Thus, the width m of the absorbing member (FIG. 
12) was able to be controlled precisely. Because of it, the width 
P(.theta.) of the parallel beams after having diverged from the light 
source image (or light source) was also able to be kept uniform with high 
accuracy. 
Namely, parallel beams having an equal cross section were emitted in 
respective directions from the light source image (or light source) formed 
by the optical integrator. 
The beams from the light source image (or light source) formed by the 
reflection type optical integrators 4a, 4b were reflected and converged by 
the special reflecting mirror 3. By this, the illuminated surface (the 
surface of mask 9) was illuminated in an arcuate pattern under the Kohler 
illumination, and in addition, the illuminated surface was illuminated 
with a uniform numerical aperture. 
The X-rays transmitted by the mask 9 were guided through the imaging 
apparatus 10 onto the substrate 11. On this occasion, the pattern on the 
mask 9 was transferred onto the substrate 11. The present embodiment used 
a silicon wafer as the substrate, and a photoresist laid on the surface 
thereof was exposed to the X-rays. In this state, moving the mask 9 and 
substrate 11 in the directions of the arrows shown in FIG. 13, the pattern 
on the entire mask surface was transferred onto the substrate. 
As a result, patterns of a minimum pattern size of 0.1 .mu.m were able to 
be obtained over a large area (about 10 cm.sup.2) on the substrate. When 
the exposure apparatus provided with the conventional illuminating 
apparatus were used, the resolution was not uniform because of the non 
uniformity of numerical aperture of illumination light, which made it very 
difficult to obtain fine patterns over a large area as achieved above. 
The fact that such fine patterns were obtained over a large area shows that 
the illuminating apparatus of the present invention has sufficient 
performance as the illuminating apparatus for exposure apparatus. Further, 
because of the capability of exposure over the large area, the throughput 
of exposure apparatus is largely improved. 
Since the wavelength of the X-rays used as the exposure light was 13 nm, 
all the reflecting mirrors were coated with a multilayer film for 
improving the reflectivity (a lamination of a plurality of alternate 
layers of molybdenum and silicon). In this case, the mirrors may be coated 
with a lamination film of a plurality of alternate layers of molybdenum and 
a silicon compound (for example, silicon carbide) as a multilayer film with 
high heat resistance. 
The present embodiment employed the transmission type mask as the mask but 
the same effects were also achieved using a reflection type mask. 
Although the reflecting curved surfaces constituting the reflection type 
optical integrator were cylindrical mirrors in the present embodiment, 
they may be fly's eye mirrors. Although the present embodiment is an 
example in which the two reflection type optical integrators were used, 
the present invention is by no means limited to it. Namely, an 
illuminating apparatus arranged in such a manner that the non-reflecting 
portions are provided on the surface of the reflection type optical 
integrator so as to limit or adjust divergent angles thereof falls within 
the scope of the present invention. 
Further, the absorbing member or non-reflecting portions of the optical 
integrator may be formed not only by the lift-off process, but also by the 
general photolithography. 
Embodiment 3 
FIG. 13 is an explanatory drawing to show the structure and layout of an 
illuminating apparatus of the present embodiment, and an exposure 
apparatus (an example) provided with the illuminating apparatus. 
The illuminating apparatus of the present embodiment is composed of an 
optical system having the light source portion 8 and the reflection type 
optical integrators 4a, 4b, and the parabolic-toric mirror (an example of 
condensing optical system) 3 as the special reflecting mirror composed of 
a part of a parabolictoric body of rotation. 
As shown in FIG. 5, the cross section in the meridional direction, of the 
special reflecting mirror 3 is a part of parabola PA, and this special 
reflecting mirror 3 is constructed of a part of a parabolic-toric body of 
rotation obtained by rotating the parabola about the base axis Ax.sub.1 
(an axis perpendicular to the symmetry axis Y) passing through the 
position Y.sub.0 apart a predetermined distance along the symmetry axis Y 
from the vertex O. Namely, as shown in FIG. 6, the special reflecting 
mirror 3 has an arcuate shape composed of a part of a belt region between 
two latitudes 31, 32 of the parabolic-toric body of rotation. 
The light source portion 8 was composed of the laser plasma X-ray source 81 
and the paraboloidal mirror 82. The laser plasma X-ray source 81 is a point 
light source having the light source size of about 100 .mu.m, from which 
X-rays diverge nearly isotropically. When the paraboloidal mirror 82 
reflects the diverging beams, the X-rays diverging from the laser plasma 
X-ray source 81 can be converted into parallel beams in a desired cross 
section. By this, parallel beams or nearly parallel beams with high 
intensity are supplied. The beams are incident to the reflection type 
optical integrator 4a. 
It is noted that the system for supplying the parallel beams is not limited 
to the combination of the light source with the curved surface mirror such 
as the paraboloidal mirror as in the above arrangement. For example, if 
the light source is one emitting nearly parallel beams, such as the 
synchrotron radiation source, the beams may be guided directly from the 
light source to the reflection type optical integrator 4a. 
When the laser plasma X-ray source is used, nearly parallel beams can also 
be guided directly from the light source to the optical integrator 4a 
without using the paraboloidal mirror and by locating the laser plasma 
X-ray source fully away from the integrator 4a. However, the arrangement 
of the present embodiment is also preferable in that case, because the 
spatial utility factor of light becomes much higher. 
As described, the light source portion 8 supplies parallel beams or nearly 
parallel beams, the beams are incident on the reflection type optical 
integrator 4a, and further, reflected beams thereby are incident on the 
reflection type optical integrator 4b. 
The reflection type optical integrator 4a is composed of an assemblage of 
cylindrical mirrors having a plurality of concave surfaces as shown in 
FIG. 14A, and converges parallel beams incident thereon in the meridional 
direction. Further, the reflection type optical integrator 4b is composed 
of an assemblage of cylindrical mirrors having a plurality of convex 
surfaces as shown in FIG. 14B, and converges parallel beams incident 
thereon in the sagittal direction. 
In the present embodiment the divergent angle 2.phi. of the reflection type 
optical integrator 4b was 60.degree.. 
In the present embodiment, the wavelength of the X-rays was 13 nm, and the 
reflecting surfaces of the reflection type optical integrators and the 
special reflecting mirror were coated with an X-ray reflecting multilayer 
film for improving the reflectivity (a lamination of a plurality of 
alternate layers of molybdenum and silicon). Particularly, the reflecting 
mirrors constituting the reflection type optical integrator 4b were given 
a distribution of period lengths of the multilayer film changing against 
the exit angle .theta.. Namely, the distribution was so arranged that the 
period length was larger in a portion with a larger exit angle, and the 
period lengths were changed between 6.7 and 6.95 nm. 
The reflectivity distribution R.sub.1 (.theta.) of this reflection type 
optical integrator is as shown in FIG. 21. 
Beams from the light source image (or light source) formed by the 
reflection type optical integrators 4a, 4b were reflected and converged by 
the special reflecting mirror 3. By this, the illuminated surface (the 
surface of mask 9) was illuminated in an arcuate pattern under the Kohler 
illumination and in addition, the illuminated surface was illuminated with 
a uniform numerical aperture. Namely, the illuminated surface was 
illuminated in the arcuate pattern with uniform intensity while 
maintaining the telecentricity under the Kohler illumination. 
The X-ray reflecting multilayer film (a lamination of a plurality of 
alternate layers of molybdenum and silicon) was formed on the surface of 
the special reflecting mirror 3, and the reflectivity distribution thereof 
R.sub.2 (.theta.) in the sagittal direction was a distribution as shown in 
FIG. 21. This reflectivity distribution was achieved by forming a 
distribution of period numbers of the multilayer film in the sagittal 
direction. Namely, a number of periods was decreased in a portion where 
X-rays at a larger exit angle were reflected. Specifically, the period 
numbers were changed between 11 and 20 periods. 
FIG. 21 shows the distribution of R.sub.1 (.theta.).multidot.R.sub.2 
(.theta.)/cos.theta. in the present embodiment. The value of R.sub.1 
(.theta.).multidot.R.sub.2 (.theta.)/cos.theta. is constant independent of 
the value of .theta.. Accordingly, the illuminating apparatus of the 
present embodiment can illuminate the illuminated surface (the surface of 
mask 9) with uniform intensity. 
X-rays transmitted by the mask 9 were guided through the imaging apparatus 
10 onto the substrate 11. On this occasion, the pattern on the mask 9 was 
transferred onto the substrate 11. In the present embodiment, the silicon 
wafer was used as the substrate, and a photoresist laid on the surface 
thereof was exposed to the X-rays. In this state, moving the mask 9 and 
substrate 11 in the directions of the arrows shown in FIG. 13, the pattern 
on the entire mask was transferred onto the substrate. 
As a result, patterns with the minimum pattern size of 0.1 .mu.m were able 
to be obtained throughout a large area (about 10 cm.sup.2) on the 
substrate. Since the exposure apparatus provided with the conventional 
illuminating apparatus were not uniform in intensity of illumination 
light, a part of the resist was subjected to excessive exposure or 
insufficient exposure, which made it very difficult to obtain fine 
patterns over a large area as achieved above. 
The fact that such fine patterns were obtained over a large area shows that 
the illuminating apparatus of the present invention has sufficient 
performance as the illuminating apparatus for exposure apparatus. Further, 
because of the capability of exposure in a large area, the throughput of 
exposure apparatus is also greatly improved. 
The present embodiment used the transmission type mask as the mask, but the 
same effects were also achieved using the reflection type mask. 
Although the reflecting curved surfaces constituting the reflection type 
optical integrator were the cylindrical mirrors in the present embodiment, 
they may be fly's eye mirrors. Further, the present embodiment was an 
example in which the two reflection type optical integrators were used, 
but the present invention is by no means limited to it. Namely, an 
illuminating apparatus that controls the intensity of illumination light 
by the reflectivity distribution of the reflection type optical integrator 
and/or the special reflecting mirror falls within the scope of the present 
invention.