JPH07235470A - Illuminator and aligner - Google Patents

Abstract

PURPOSE:To provide an illuminator which can be manufactured easier without significant sacrifice of X-ray reflectance and an aligner equipped with the illuminator. CONSTITUTION:The illuminator comprises a light source 1 projecting a parallel luminous flux, a reflective optical integrator 2 for forming a plurality of light source images from the collimated luminous flux, and a special reflector 3 having a reflective surface performing critical illumination in the meridional direction of a condensing optical system and a reflective surface performing Keller illumination in the sagittal direction and converting the luminous flux from the light source image or light source into collimated luminous flux thus illuminating an object to be illuminated arcuately. The special reflector 3 is constituted of a part of a parabolic toric body of rotation obtained by rotating a parabola about a reference axis Ax1 passing normally to the symmetric axis Ax0 at a position separated by a predetermined distance from the apex O of the parabola along the symmetry axis Ax0 thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device for illuminating an object to be illuminated in an arc shape, and an exposure device equipped with the device, and more particularly to a photomask by a mirror projection method such as an X-ray optical system. The present invention relates to an apparatus suitable for transferring a circuit pattern on a (mask or reticle) onto a substrate such as a wafer via a reflection type image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in exposure in semiconductor manufacturing, a circuit pattern formed on a photomask (hereinafter referred to as a mask) surface as an object surface is passed through an imaging device to form a substrate such as a wafer (hereinafter referred to as a substrate). (Referred to as “) is projected and transferred onto the surface.
When the exposure light is an X-ray or the like, the image forming apparatus is composed of a reflecting mirror, and only the arc-shaped good image area outside the axis of the image forming optical system is used, and only the arc area on the mask is on the wafer. Is projected and transferred to. Further, the transfer of the circuit pattern of the entire mask onto the wafer is performed by scanning the mask and the wafer in a fixed direction.

The exposure by this scanning method has an advantage that a relatively high throughput and a high resolution can be obtained. In this type of exposure, an illumination optical system capable of uniformly illuminating the entire arc region on the mask with a constant numerical aperture (NA) is desired, and Japanese Patent Application No. 4-242486 by the same applicant as the present application ( Unpublished) proposes an illumination optical system capable of uniformly illuminating a mask in an arc shape.

The optical system proposed in this Japanese Patent Application No. 4-242486 is shown in FIGS. A parabola is defined as PA, the apex O of this parabola PA is the origin, the symmetry axis Ax ₀ of the parabola PA passing through this apex O is the Y axis, and this symmetry axis Ax.
_An axis orthogonal to ₀ (hereinafter referred to as the Y axis) and passing through the vertex O is shown as the X axis. As shown in FIG. 5, the cross section of the special reflecting mirror 3 in the meridional direction forms a part of the parabola PA, and the special reflecting mirror 3 extends from the vertex O to the symmetry axis Y.
Along the reference axis A passing through a position Y ₀ separated by a predetermined distance
It is composed of a part of a parabolic toric rotor rotated about x ₁ (axis perpendicular to the axis of symmetry Y). That is, as shown in FIG. 6, the special reflecting mirror 3 is formed of a part of a band-shaped region sandwiched by two parallels 31 and 32 of the parabolic toric-shaped rotating body, and has an arc shape. .

The function of the special reflecting mirror 3 relating to the luminous flux in the meridional direction will be described with reference to FIG. The light flux in the meridional direction means a light flux in a plane (meridional plane) including the reference axis Ax ₁ of the special reflecting mirror 3, and the light flux in the sagittal direction is in a plane (sagittal plane) orthogonal to the meridional plane. Means the luminous flux of. Now, when a light source image (or light source) I having a predetermined size is formed at a predetermined position on the reference axis Ax ₁ by an optical system (not shown), a light flux from any one point on this light source image (or light source) I Is a special reflector 3
Is converted into a parallel light beam by the condensing action of.

For example, a light beam from the center a of the light source image (or light source) I is converted into a parallel light beam by the special reflecting mirror 3 and vertically illuminates the area BA ₀ on the illuminated surface to obtain a light source image (or light source). ) I, the light flux from the lower side b is converted into a parallel light flux by the special reflecting mirror 3 and illuminates the area BA ₀ on the irradiated surface from the right oblique direction. Then, the light flux from above c of the light source image (or light source) I is converted into a parallel light flux by the special reflecting mirror 3 and illuminates the area BA ₀ on the illuminated surface from the left oblique direction.

As described above, the light flux from each position of the light source image (or light source) I is converted into a parallel light flux by the special reflecting mirror 3 and uniformly illuminates the area BA ₀ on the illuminated surface in a superimposed manner. Also, looking at the numerical aperture in the meridional direction by the special reflecting mirror 3 at this time, the parallel light flux (light flux shown by the solid line) from the light source image (or light source) I parallel to the optical axis AX ₂₀ is reflected by the special reflecting mirror 3. Under the numerical aperture NA _M (= sin θ _M ), the light is focused at the center on the area BA _{0 of the} illuminated surface and has a divergence angle ε ₁ with respect to the optical axis AX ₂₀ . The parallel light flux (the light flux indicated by the dotted line) is reflected by the special reflecting mirror 3 to have a numerical aperture N.
Under A _M, the light is focused at the left end on the area BA _{0 of the} irradiated surface. Then, (light flux shown by the dotted line) parallel light beam from the light source images (or source) I to the divergence angle epsilon ₁ with divergence angle epsilon ₂ divergence angle epsilon ₁ equal angle in the opposite direction (= epsilon _1), a special The area of the irradiated surface BA ₀ under the numerical aperture NA _M by the reflecting mirror 3.
It is collected at the upper right edge. The optical axis AX ₂₀ is bent 90 degrees by the special reflecting mirror 3.

Therefore, a parallel light flux having an arbitrary divergence angle from the light source image (or light source) I has a constant numerical aperture NA from any position on the illuminated surface area BA _{0 in} the meridional direction.
The principal rays (P _a , P _b , P _c ) of the parallel light flux that are condensed under _M and are emitted from the light source image (or light source) I have the optical axis Ax.
_{It is} always parallel to ₂₀ , and it can be seen that the telecentricity is maintained.

Next, the function of the special reflecting mirror 3 in the sagittal direction will be described with reference to FIG. The parallel light flux L ₀ from the light source image (or light source) I formed on the reference axis Ax ₁ is condensed by the special reflecting mirror 3 in the area BA _{0 on the} illuminated surface, and the angle φ is smaller than the parallel light flux L _0. The parallel light flux L ₁ from the light source image (or light source) I emitted with an inclined divergence angle is condensed by the special reflecting mirror 3 on the area BA _{1 of the} illuminated surface.

Here, of the light flux from the light source image (or light source) I forming the area BA _{1 of the} illuminated surface, the light flux in the sagittal direction will be examined. Similar to the case of FIG. 5, a parallel light flux having an arbitrary divergence angle from the light source image (or light source) I has a constant numerical aperture NA _M at any position in the meridional direction on the area BA _{1 of the} illuminated surface. The principal ray of the parallel light flux that is originally condensed and is from the light source image (or light source) I has an optical axis Ax _21.
It is always parallel to, and the telecentricity is maintained.

Therefore, a parallel light flux is radiated from the light source image (or light source) I formed on the reference axis Ax _{1 in} the arc direction of the special reflecting mirror 3 (the parallel lines 31 and 32 of the parabolic toric rotor). Even if the light is emitted to, the arc-shaped illumination area BF is formed while maintaining the telecentricity. The arc-shaped illumination area BF corresponds to the illuminated surface, and the light source image or the light source exists at the infinite position with respect to the illuminated surface. Here, below the illuminated surface, a telecentric projection optical system is provided on the incident side, and a light source image is formed at the entrance pupil position of this projection optical system. Therefore, it can be understood that the irradiated surface is so-called Koehler illumination.

In the illumination device, the light source image (or light source) I formed on the reference axis Ax ₁ is produced by, for example, an optical integrator. On the other hand, in order to configure an optical system in the region of light with a short wavelength such as X-rays, all members of the optical system must be reflective members.
Therefore, the optical integrator used in the short wavelength region must also be a reflective type.

As a reflection type optical integrator, for example, there is a fly-eye mirror in which a plurality of curved mirrors are two-dimensionally arranged as shown in FIG. The plurality of curved mirrors is, for example, a cross-sectional view of FIG. 8B (e- of FIG. 8A).
It is a concave mirror as shown in (e ′ cross section). With such a fly-eye mirror, a light source image (or light source) in which minute light sources 9 are two-dimensionally arranged is formed (see FIG. 8C).

Here, a case where the illumination optical system (disclosed in Japanese Patent Application No. 4-242486) is used in a soft X-ray exposure apparatus will be described with reference to FIG. FIG. 7A shows a cross section of the illumination optical system in the meridional direction. In the figure, the optical system is shown as a transmissive type for ease of explanation, but the actual optical system is a reflective type. X-rays diverging from an X-ray source (an example of a light source of a light source means) 4 are converted into a parallel light flux by a reflecting mirror 5, and a reflection type optical integrator 2 produces a light source image (or light source) composed of a plurality of minute light sources 9. It is formed. Further, the X-rays emitted from the light source image (or the light source) are converted into parallel light by the special reflecting mirror 3 and illuminate the irradiation surface BF.

At this time, the divergence angle θ _i1 of the X-ray diverging from the light source image (or light source) is determined by the width L _{1 of the} illumination area and the distance between the light source image (or light source) and the special reflecting mirror 3. In this case, L ₁ can be approximated to the length of an arc whose radius is the distance. For example, when L ₁ is 2 mm and the distance is 120 mm, the divergence angle θ _i1 is about 1 °. Next, a cross section in the sagittal direction of the illumination optical system will be described with reference to FIG. The X-rays diverging from the X-ray source 4 are converted into a parallel light flux by the reflecting mirror 5, and the reflection type optical integrator 2 forms a light source image (or light source) composed of a plurality of minute light sources 9. Further, the X-rays emitted from the light source image (or the light source) are converted into parallel light by the special reflecting mirror 3 and illuminate the irradiation surface BF.

At this time, the divergence angle θ _i2 of the X-ray diverging from the light source image (or light source) is determined by the width L _{2 of the} illumination area and the distance between the light source image (or light source) and the special reflecting mirror 3. In this case, L ₂ can be approximated to the length of an arc whose radius is the distance. For example, when L ₂ is 2 mm and the distance is 120 mm, the divergence angle θ _i2 is about 60 °. Therefore, in such a case, it is necessary for the reflection type optical integrator to make the divergence angle greatly different between the sagittal direction and the meridional direction.

[0017]

As described above, there is a fly-eye mirror as shown in FIG. 9A, for example, as a reflection type optical integrator whose divergence angle greatly differs depending on the direction. The plurality of curved mirrors forming the fly-eye mirror are, for example, spherical mirrors cut into a rectangle. The cross section has a shape as shown in FIGS. 9 (b-1) and 9 (b-2). Here, FIG. 9 (b-1) is an ff 'cross section of FIG. 9 (a), and FIG. 9 (b-2) is a gg' cross section of FIG. 9 (a).

However, the light source image (or light source) formed by such a fly-eye mirror has a minute light source 9 in the meridional direction and the sagittal direction, as shown in FIG. 9C.
The numbers are different. As described above, if the number of the minute light sources 9 is different depending on the direction, the direction of the resolution of the exposure apparatus is generally uneven, which is not preferable. Further, in this case, it is conceivable to reduce the direction unevenness by increasing the number of minute light sources. However, in order to increase the number of secondary light sources, the size of the curved mirror forming the fly-eye mirror is reduced. However, there is a problem that it is difficult to manufacture.

Further, if the reflection type optical integrator is composed of a plurality of fly-eye mirrors, it is possible to make the number of minute light sources in the meridional direction and the sagittal direction equal, but in the soft X-ray region, the reflection of the reflection mirror is reduced. Since the reflectivity is low, when a plurality of fly-eye mirrors are used as the reflection type optical integrator, there is a problem that the X-ray reflectivity of the entire illumination optical system is significantly reduced. In addition, this also reduces the throughput of the exposure apparatus.

Therefore, the present invention solves the above problems,
It is an object of the present invention to provide an illuminating device that is easier to manufacture than before and does not significantly reduce the X-ray reflectance, and an exposure device including the illuminating device.

[0021]

Therefore, the first aspect of the present invention is to provide "a light source means for forming at least a light source image or a light source having a predetermined size, and an object to be illuminated by condensing a light beam from the light source means. In a lighting device comprising a condensing optical system for illuminating, a light source unit for supplying a parallel light flux,
It has a reflection type optical integrator that forms a plurality of light source images by parallel light flux from the light source section, and the reflection type optical integrator has a reflection surface that forms critical illumination in the meridional direction of the condensing optical system. , A reflection surface that forms Koehler illumination in the sagittal direction is provided, and the condensing optical system converts the light source image or the light flux from the light source into a parallel light flux to illuminate the illuminated object in an arc shape. The special reflecting mirror has a mirror, and the special reflecting mirror is a parabola rotated about a reference axis passing through a position perpendicular to the symmetry axis at a position separated from the apex of the parabola by a predetermined distance along the symmetry axis of the parabola. An illumination device (claim 1) characterized in that the illumination device is configured by a part of a toric rotor.

Further, the present invention secondly provides that "the reflective optical integrator has a plurality of cylindrical reflective surfaces continuously and integrally formed in only one direction. Lighting device (claim 2) "
I will provide a. Further, a third aspect of the present invention is that an X-ray reflection multilayer film is provided on the reflection surfaces of the reflection type optical integrator and the special reflection mirror.
Or a lighting device according to claim 2 (claim 3).

In a fourth aspect of the present invention, "the X-ray reflection multilayer film is molybdenum / silicon, molybdenum / silicon compound, ruthenium / silicon, ruthenium / silicon compound,
The illumination device according to claim 3, wherein the illumination device is formed by alternately laminating a plurality of combinations of rhodium / silicon or a combination of rhodium / silicon compounds. "I will provide a.

In a fifth aspect, the present invention provides an "exposure device (claim 5) including the illuminating device according to claims 1 to 4".

[0025]

FIG. 1 shows an optical system of an illuminating device (one example) according to the present invention, which includes a light source unit 1, a reflection type optical integrator 2, a light source image (or light source) I, and a special reflecting mirror (condensing optical system) 3. FIG. 7 is a cross-sectional view in the meridional direction of FIG. As shown in FIG. 5, the cross section of the special reflecting mirror 3 in the meridional direction forms a part of the parabola PA.
Is a parabolic toric rotor that is rotated about a reference axis Ax ₁ (axis perpendicular to the axis of symmetry) passing through a position Y ₀ that is separated from the vertex O by a predetermined distance along the axis of symmetry Y. It is composed of parts. That is, as shown in FIG. 6, the special reflecting mirror 3 has two parallel lines 3 of the parabolic toric rotor.
It is composed of a part of a band-shaped region sandwiched by 1 and 32, and has an arc shape.

The light source unit 1 supplies a parallel light beam or a light beam that is nearly parallel, and this light beam is incident on the reflection type optical integrator 2. The reflection type optical integrator 2 is provided with a reflection surface for critical illumination in the meridional direction and a reflection surface for Koehler illumination in the sagittal direction.
Such a reflection type optical integrator 2 is shown in FIGS. 3A and 3B (cross section d-d 'in FIG. 3A).
As shown in FIG. 5, for example, a cylindrical reflecting surface (an example of a curved mirror) is integrally formed continuously in only one direction. That is, the reflective optical integrator 2 according to the present invention has a simpler structure than the conventional reflective optical integrator using the fly-eye mirror. Further, it is not necessary to make the reflecting surface as small as a fly-eye mirror in order to eliminate unevenness in the resolution direction in the exposure apparatus. Therefore, the reflective optical integrator 2 according to the present invention is easy to manufacture.

Further, the reflection type optical integrator 2 according to the present invention has a plurality of reflection surfaces integrally formed, and therefore, as a reflection type optical integrator,
Unlike the case of using a plurality of fly-eye mirrors, the X-ray reflectance of the illumination optical system as a whole does not drop significantly. The reflection type optical integrator 2 condenses the incident parallel light flux linearly in the sagittal direction on the reference axis Ax ₁ . Therefore, a light source image (or light source) I composed of an assembly of linear light sources 9 corresponding to the number of the cylindrical reflecting surfaces (an example of a curved mirror) is formed at the light collecting place (see FIG. 3C). ).

The light flux from the light source image (or light source) I thus formed is reflected and condensed by the special reflecting mirror 3, and the illuminated surface is illuminated in an arc shape. An optical system of the illumination device according to the present invention will be described with reference to FIG. In FIG. 2, the optical system is shown as a transmission type for ease of explanation, but the actual optical system is a reflection type.

FIG. 2A shows a sectional view of the optical system of the illuminating device in the meridional direction. The X-rays diverging from the X-ray source 4 are converted into parallel light fluxes by the reflecting mirror 5 and the like, and enter a reflection type optical integrator (not shown). Here, since the reflection type optical integrator has no condensing effect on the light flux in the meridional direction, a parallel light flux is emitted from the reflection type optical integrator in the meridional direction.

The X-rays emitted from the reflection type optical integrator in the meridional direction are condensed by the special reflection mirror 3 and illuminate the irradiated surface BF. At this time, the parallel light that has entered the special reflecting mirror 3 is condensed at one point on the irradiation surface BF. That is, the X-rays diverging from one point on the X-ray source 4 are focused on one point on the irradiated surface BF in the meridional direction (cross section) via the optical system. Therefore, the illuminated surface is in the meridional direction (arc-shaped illuminated surface BF
Critical illumination in the radial direction of the circular arc (direction parallel to the Ax ₀ axis) so that the uniformity of the numerical aperture is satisfied.

The uniformity of the intensity in the meridional direction becomes non-uniform when the spatial intensity distribution of the X-ray source 4 is non-uniform. However, in the exposure apparatus, since the mask and the wafer are scanned in one direction, the unevenness of the intensity distribution in the scanning direction is eliminated. That is, by making the scanning direction coincide with the meridional direction, non-uniformity of the intensity distribution in the meridional direction is eliminated. Therefore, in the meridional direction of the surface to be illuminated BF, sufficient illumination is provided by the critical illumination.

The width (width in the meridional direction) L ₁ of the illumination light on the irradiated surface BF is the size L of the X-ray source 4.
₃ and the magnification of the illumination optical system in the meridional direction (see FIG. 2 (a)). Synchrotron radiation (SR) and laser plasma X, which are typical soft X-ray sources
Since the size of the radiation source (LPX) is as small as about 1 mm or less, the width L ₁ can be made sufficiently small unless the magnification of the illumination optical system is made extremely large. The light loss can also be made sufficiently small.

Next, the sagittal direction of the optical system of the illumination device according to the present invention will be described with reference to FIG. FIG. 2B shows a sagittal sectional view of an optical system of the illumination device. The X-rays diverging from the X-ray source 4 are converted into parallel light fluxes by the reflecting mirror 5 and the like, and enter the reflection type optical integrator 2. Since the reflection type optical integrator 2 has a condensing effect on the light beam in the sagittal direction, it forms a light source image (or light source) composed of a plurality of minute light sources (linear light sources) 9 in the sagittal direction. This light source image (or light source) is formed by arranging linear minute light sources 9 in a line in the sagittal direction, as shown in FIG.

The X-rays diverged in the sagittal direction from the light source image (or light source) composed of a plurality of minute light sources (linear light sources) 9 are converted into parallel light by the special reflecting mirror 3 and illuminate the illuminated surface BF. That is, the irradiated surface BF is Koehler-illuminated in the sagittal direction so that the numerical aperture and the uniformity of the illumination intensity are simultaneously satisfied. The reflective surface constituting the reflective optical integrator according to the present invention may be a concave surface or a convex surface. When the reflecting surface is a concave surface, the light source image (or light source) I is formed on the exit side of the reflecting surface.
By arranging on the left side of the reference axis Ax ₁ , the light source image (or light source) I can be formed on the reference axis Ax ₁ . When the reflecting surface is a convex surface, the light source image (or light source) I is formed on the side opposite to the emitting side of the reflecting surface, so that the reflection-type optical integrator 2 is used as a reference on the paper surface of FIG. Axis A
By arranging on the right side of x ₁ , the light source image (or light source)
I can be formed on the reference axis Ax ₁ .

The reflective surfaces of the reflective optical integrator and the special reflective mirror according to the present invention are preferably formed by an X-ray reflective multilayer film. In addition, the X-ray reflective multilayer film is molybdenum / silicon, molybdenum / silicon compound, ruthenium / silicon, ruthenium / silicon compound, rhodium /
It is preferable that any one of a combination of silicon and a rhodium / silicon compound is alternately laminated a plurality of times (preferably in the case of an X-ray having a wavelength of about 13 nm).

As described above, the reflection type optical integrator according to the present invention is easier to manufacture than the conventional one, and the X-ray reflectance is not significantly lowered. Further, in the illumination device provided with such a reflection type optical integrator, the illuminated surface is in the meridional direction,
It is illuminated with a critical illumination so that the uniformity of the numerical aperture is satisfied. Further, the irradiated surface is Koehler-illuminated in the sagittal direction so that the numerical aperture and the uniformity of the illumination intensity are simultaneously satisfied.

That is, according to the illumination device of the present invention, it is possible to illuminate the surface to be illuminated in an arc shape with uniform intensity. Therefore, in the exposure apparatus equipped with the illumination device of the present invention, an image can be obtained with a uniform exposure amount on the entire surface of the arc which is the irradiation surface, and as a result, the mask pattern on the irradiation surface can be formed with high throughput. It can be accurately transferred onto the substrate.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The illumination device of the present embodiment is a parabolic toric surface which is a special reflecting mirror composed of an optical means having a light source section 1 and a reflection type optical integrator 2 and a part of a parabolic toric rotor. And a mirror (an example of a condensing optical system) 3 (see FIG. 1).

As shown in FIG. 5, the cross section of the special reflecting mirror 3 in the meridional direction forms a part of the parabola PA,
This special reflecting mirror 3 has a parabolic toric shape rotated about a reference axis Ax ₁ (an axis perpendicular to the axis of symmetry Y) passing through a position Y ₀ separated from the vertex O by a predetermined distance along the axis of symmetry Y. It is composed of a part of the rotating body. That is, as shown in FIG. 6, the special reflecting mirror 3 is formed of a part of a band-shaped region sandwiched by two parallels 31 and 32 of the parabolic toric-shaped rotating body, and has an arc shape. .

The light source unit 1 supplies a parallel light beam or a light beam that is nearly parallel, and this light beam is incident on the reflection type optical integrator 2. The reflection-type optical integrator 2 includes the reflection optical integrator 2 shown in FIGS. 3A and 3B (d- in FIG.
As shown in (d ′ cross section), a cylindrical reflecting surface (an example of a curved mirror) is continuously and integrally formed only in one direction.

That is, the reflection type optical integrator 2 of this embodiment is simpler in structure than the conventional reflection type optical integrator using the fly-eye mirror. Further, it is not necessary to make the reflecting surface as small as a fly-eye mirror in order to eliminate unevenness in the resolution direction in the exposure apparatus. Therefore, the reflective optical integrator 2 of this embodiment is easy to manufacture.

Further, since the reflection type optical integrator 2 of the present embodiment has a plurality of reflection surfaces integrally formed, as in the case of using a plurality of fly-eye mirrors as the reflection type optical integrator, an illumination optical system is used. The X-ray reflectance as a whole does not significantly decrease.
The reflection type optical integrator 2 condenses the incident parallel light flux linearly in the sagittal direction on the reference axis Ax ₁ . Therefore, a light source image (or light source) I composed of a group of linear light sources 9 corresponding to the number of the cylindrical reflecting surfaces (an example of a curved mirror) is formed at the light collecting place (FIG. 3C. )reference).

The light flux from the light source image (or light source) I thus formed is reflected and condensed by the special reflecting mirror 3, and the illuminated surface is illuminated in an arc shape. The illuminated surface is critically illuminated in the meridional direction (the radial direction of the arc of the arcuate illuminated surface BF, the direction parallel to the Ax ₀ axis) so that the uniformity of the numerical aperture is satisfied. Further, the irradiated surface BF is subjected to Koehler illumination in the sagittal direction so that the numerical aperture and the uniformity of illumination intensity are simultaneously satisfied.

FIG. 4 is an explanatory view showing the configuration and arrangement of the illumination device of this embodiment and an exposure device (one example) equipped with the device. The light source unit is composed of a laser plasma X-ray source 41 and a parabolic mirror 51. The laser plasma X-ray source 41 is
A point light source with a light source size of about 100 μm, from which X-rays diverge almost isotropically. This divergent light is parabolic mirror 5
Laser plasma X-ray source 4 by reflecting at 1
The X-rays diverging from 1 can be converted into a parallel light flux having a desired cross-sectional shape. As a result, a high-intensity parallel light flux or a near-parallel light flux is supplied. This light flux enters the reflection type optical integrator 2.

The means for supplying the parallel light flux is not limited to the above-mentioned combination of the light source and the curved mirror such as a parabolic mirror. For example, in the case of a light source such as a synchrotron radiation light source that emits light close to parallel light, the light may be directly incident on the reflection type optical integrator 2. Even in the case of the laser plasma X-ray source, by arranging the laser plasma X-ray source and the integrator 2 so far as to be separated from each other, the light close to the parallel light is incident on the optical integrator 2 directly from the light source without using a parabolic mirror. However, the spatial arrangement efficiency of light is remarkably improved by the arrangement as in this embodiment, which is preferable.

In this way, the light source section supplies a parallel light beam or a light beam that is nearly parallel, and this light beam is incident on the reflection type optical integrator 2. The X-ray emitted from the reflection type optical integrator 2 was reflected by the special reflection mirror 3 to illuminate the mask 6 in an arc shape. At this time, the width of the arc-shaped illuminated surface (the width in the meridional direction) is set to be smaller than the width in which a good image can be obtained in the imaging device 7. The illuminated surface (mask surface) was critically illuminated in the meridional direction so that the uniformity of the numerical aperture was satisfied. The surface to be irradiated was Koehler-illuminated in the sagittal direction so that the numerical aperture and the uniformity of the illumination intensity were simultaneously satisfied.

The magnification of the illumination optical system of the illumination device in the meridional direction (the magnification of the critical illumination optical system) was set to 20 times. The light source size of the laser plasma X-ray source is about 1
Since it is 00 μm, the width (width in the meridional direction) of the illumination area (arc shape) on the mask that is the irradiation surface is about 2 m.
It became m. In the image forming apparatus 7 of the present embodiment, since a width capable of obtaining a good image is about 2 mm, most of the illumination light is introduced into the image forming optical system of the image forming apparatus and contributes to image formation. In the imaging device 7, the light irradiating other than the area where a good image is obtained needs to be removed by, for example, a slit (not shown), but in the case of the present embodiment, the mask which is the surface to be irradiated is used. Width of upper illumination area (arc shape) (width in meridional direction)
Then, in the image forming device 7, the width at which a good image is obtained is substantially equal (about 2 mm), so that the light (X-ray) to be removed by the slit or the like is extremely small. Therefore, in this embodiment, the spatial utilization efficiency of X-rays is high.

The X-ray transmitted through the mask 6 was irradiated onto the substrate 8 through the image forming device 7 having a magnification of 1/4. At this time,
The pattern of the mask 6 was transferred onto the substrate 8. In this example, a silicon wafer was used as the substrate, and the resist coated on the surface was exposed by X-rays. In this state, the mask 6 and the substrate 8 were scanned in the direction of the arrow shown in FIG. 4 to transfer the pattern on the entire surface of the mask onto the substrate.

In the present embodiment, the frequency of pulsed light emission of the laser plasma X-ray source was 500 Hz, and the scanning speed of the mask was 24 mm / sec. Since the width of the illumination light in the scanning direction (width in the meridional direction) is about 2 mm, each point on the mask is illuminated with about 40 pulses of X-rays by scanning. Since the spatial and temporal intensity distribution of the laser plasma X-ray source is not necessarily uniform, the X-ray intensity of each pulse is not constant. However, when scanning as described above,
By illuminating each point on the mask with multiple pulses,
The integrated value is constant at each point on the mask, and it is possible to illuminate with uniform intensity.

As a result, by scanning an arc-shaped exposure region having a length of 30 mm on the substrate for about 35 mm, a pattern having a minimum pattern size of 0.1 μm can be obtained on the substrate over a large area (about 10 cm ² ). It was The fact that such a minute pattern is obtained in a large area indicates that the illumination device of the present invention has sufficient performance as an illumination device for an exposure apparatus. Furthermore, since a large area can be exposed, the throughput of the exposure apparatus is also greatly improved.

When a synchrotron radiation light source is used as a means for supplying a parallel light flux, the magnification of the critical illumination optical system in the meridional direction of the illumination device is sufficiently smaller than 1, so that the width of the illumination light ( (Width in the meridional direction)
However, since the synchrotron radiation is a continuous emission light source, exposure unevenness does not occur in the scanning direction. Also,
In this embodiment, the critical illumination optical system has a magnification of 20 in the meridional direction of the illumination device, but the present invention is not limited to this. For example, the magnification may be further increased. At this time, since the numerical aperture on the light source side in the section in the meridional direction becomes large, in the case of a divergent light source such as a laser plasma X-ray source, the diverging X-rays Since it can be taken into the lighting device with a large solid angle, the intensity of the illumination light can be increased.

In the present embodiment, the slit is provided in the illumination device, but the width of the arc of the arc-shaped illumination area (width in the meridional direction) is sufficiently smaller than the width at which a good image can be obtained in the imaging device. By doing so, the slit can be omitted. The width of the arc can be easily set by adjusting the magnification of the illumination optical system. The reflective optical integrator of this example was easier to fabricate than the conventional one, and the X-ray reflectance was not significantly reduced.

Further, in the illuminating device provided with such a reflection type optical integrator, the illuminated surface was critically illuminated in the meridional direction and illuminated so that the uniformity of the numerical aperture was satisfied. The surface to be irradiated was Koehler-illuminated in the sagittal direction so that the numerical aperture and the uniformity of the illumination intensity were simultaneously satisfied. That is, according to the illuminating device of the present embodiment, it was possible to illuminate the illuminated surface in an arc shape with uniform intensity. Therefore, in the exposure apparatus including the illumination device of the present embodiment, an image can be obtained with a uniform exposure amount on the entire surface of the arc which is the irradiation surface, and as a result, the pattern of the mask on the irradiation surface can be obtained with high throughput. Could be accurately transferred onto the substrate.

In this embodiment, a transmissive mask is used as the mask, but the same effect can be obtained by using a reflective mask. In this embodiment, the wavelength of X-rays is set to 13 nm, and the reflection surfaces of the reflection type optical integrator and the special reflection mirror are provided with an X-ray reflection multilayer film for improving the reflectance (molybdenum and silicon are alternately laminated a plurality of times). ) Was coated.

[0056]

As described above, the reflection type optical integrator according to the present invention is easier to manufacture than the conventional one, and the X-ray reflectance is not significantly lowered. Further, in the illumination device provided with such a reflection type optical integrator, the illuminated surface is in the meridional direction,
It is illuminated with a critical illumination so that the uniformity of the numerical aperture is satisfied. Further, the irradiated surface is Koehler-illuminated in the sagittal direction so that the numerical aperture and the uniformity of the illumination intensity are simultaneously satisfied.

That is, according to the illumination device of the present invention, it is possible to illuminate the surface to be illuminated in an arc shape with a uniform intensity. Therefore, in the exposure apparatus equipped with the illumination device of the present invention, an image can be obtained with a uniform exposure amount on the entire surface of the arc which is the irradiation surface, and as a result, the mask pattern on the irradiation surface can be formed with high throughput. It can be accurately transferred onto the substrate.

[Brief description of drawings]

FIG. 1 is an optical system of an illuminating device (one example) according to the present invention, which includes a light source unit 1, a reflection type optical integrator 2, a light source image (or light source) I, and a special reflecting mirror (condensing optical system) 3. It is sectional drawing in the meridional direction.

FIG. 2 is an optical system of an illuminating device (one example) according to the present invention. (A) is a sectional view of the optical system in the meridional direction, and (b) is a sectional view of the optical system in the sagittal direction.

FIG. 3 is an example of a reflection type optical integrator according to the present invention, (a) is a plan view, (b) is a sectional view,
(C) is a plan view of a light source image (or light source) formed by the reflection type optical integrator.

FIG. 4 is an explanatory diagram showing a configuration and an arrangement of an illumination device of an embodiment and an exposure device (one example) including the illumination device.

FIG. 5 is an optical system (an example) of the illumination device according to the present invention, which includes a light source image (or light source) I, a special reflecting mirror (condensing optical system) 3, and a meridional of a region BA _{0 on} the illuminated surface. It is sectional drawing of a direction.

6 is a perspective view of a light source image (or light source) I, a special reflecting mirror (condensing optical system) 3, and an arc-shaped illuminated area BF, which is an optical system (an example) of the illumination device according to the present invention. FIG. Is.

FIG. 7 shows an optical system of a conventional lighting device (one example).
(A) is a sectional view of the optical system in the meridional direction, and (b) is a sectional view of the optical system in the sagittal direction.

FIG. 8 is a plan view (a), a sectional view (b) and a light source formed by the mirror, which is an example of a conventional reflection type optical integrator (without anisotropy of divergence angle). It is a top view (c) of an image (or a light source).

FIG. 9 is a plan view (a) and a sectional view (b-1, of a fly-eye mirror, which is an example of a conventional reflection-type optical integrator (where the divergence angle varies greatly depending on the direction).
b-2) and a plan view (c) of a light source image (or light source) formed by the mirror.

[Explanation of symbols for main parts]

 DESCRIPTION OF SYMBOLS 1 ... Light source part 2 ... Reflection type optical integrator 3 ... Special reflection mirror (condensing optical system) 4,41 ... Light source (X-ray source as an example) 5, 51 ... Reflection mirror 6・ ・ ・ Mask 7 ・ ・ ・ Imaging device 8 ・ ・ ・ Substrate BF ・ ・ ・ Arc-shaped illuminated area I ・ ・ ・ Light source image (or light source)

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

At this time, the divergence angle θ _i1 of the X-ray diverging from the light source image (or light source) is determined by the width L _{1 of the} illumination area and the distance between the light source image (or light source) and the special reflecting mirror 3. For example, when L ₁ is 2 mm and the distance is 120 mm, the divergence angle θ _i1 is about 1 °. Next, using FIG. 7B,
A section of the illumination optical system in the sagittal direction will be described. The X-rays diverging from the X-ray source 4 are converted into a parallel light flux by the reflecting mirror 5, and the reflection type optical integrator 2 forms a light source image (or light source) composed of a plurality of minute light sources 9. Further, the X-rays emitted from the light source image (or the light source) are converted into parallel light by the special reflecting mirror 3,
The illuminated surface BF is illuminated.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

At this time, the divergence angle θ _i2 of the X-ray diverging from the light source image (or light source) is determined by the width L _{2 of the} illumination area and the distance between the light source image (or light source) and the special reflecting mirror 3. For example, when L ₂ is 2 mm and the distance is 120 mm, the divergence angle θ _i2 is about 60 °. Therefore, in such a case, it is necessary for the reflection type optical integrator to make the divergence angle greatly different between the sagittal direction and the meridional direction.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G03F 7/20 521 G21K 1/06 M 5/02 X

Claims (5)

[Claims] 1. An illumination device comprising at least a light source means for forming a light source image or a light source of a predetermined size, and a condensing optical system for condensing a light flux from the light source means to illuminate an illuminated object. In the above, the light source means has a light source section that supplies a parallel light flux, and a reflection type optical integrator that forms a plurality of light source images by the parallel light flux from the light source section, and the reflection type optical integrator is A reflective surface that forms critical illumination in the meridional direction of the condensing optical system,
A reflecting surface for providing Koehler illumination in the sagittal direction is provided, and the condensing optical system converts the light source image or a light flux from the light source into a parallel light flux to illuminate the illuminated object in an arc shape. The special reflecting mirror has a parabolic toric rotated about a reference axis passing perpendicularly to the symmetry axis at a position separated from the apex of the parabola by a predetermined distance along the symmetry axis of the parabola. An illumination device comprising a part of a shaped rotating body. 2. The lighting device according to claim 1, wherein the reflection type optical integrator has a plurality of cylindrical reflection surfaces integrally formed continuously in only one direction. 3. The lighting device according to claim 1, wherein an X-ray reflection multilayer film is provided on the reflection surfaces of the reflection type optical integrator and the special reflection mirror. 4. The combination of any one of molybdenum / silicon, molybdenum / silicon compounds, ruthenium / silicon compounds, ruthenium / silicon compounds, rhodium / silicon, or rhodium / silicon compounds in the X-ray reflective multilayer film. The lighting device according to claim 3, wherein the lighting device is formed by alternately laminating a plurality of times. 5. An exposure apparatus comprising the illumination device according to claim 1.