JP2002015979A - Optical projection system, system and method for exposure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical projection system, capable of suppressing a temperature elevation on each reflection plane, while setting reflection to be at least six planes, and having satisfactory image-forming performance, and to provide an exposure system and a method of exposure. SOLUTION: An optical projection system PL is provided with a first reflecting mirror M1 having a concave reflecting lane, a second reflecting mirror M2 having a concave reflecting plane, a third reflecting mirror M3 having a convex reflecting plane, a fourth reflecting mirror M4 having a concave reflecting plane, a fifth reflecting mirror M5 having a convex reflecting plane and a sixth reflecting mirror M6 having a concave reflecting plane. Then, the apex of the fourth reflecting mirror M4 is located on the side of a second plane W rather than the apex of the first reflecting mirror M1, and the apex of the sixth reflecting mirror M6 is located between the apex of the third reflecting mirror M3 and the apex of the forth reflecting mirror M4. Thus, the image of an object on a first lane R is formed on the second plane W, without forming an intermediate image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection optical system for forming, for example, a reduced image of a mask pattern on a substrate, and an exposure apparatus and an exposure method having the projection optical system.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device or a liquid crystal display device is manufactured by lithography, a mask on which a pattern is formed is illuminated with illumination light for exposure (exposure light), and an image of the pattern of the mask is formed. Is projected onto a substrate such as a semiconductor wafer or a glass plate coated with a photosensitive agent such as a photoresist through a projection optical system, but in recent years there has been a demand for finer patterns. Due to the increasing demand, an exposure apparatus for performing this projection exposure is required to have a higher resolution.

In order to satisfy this requirement, it is necessary to shorten the wavelength of the exposure light emitted from the light source and increase the numerical aperture (NA) of the optical system. However, when the wavelength of the exposure light is shortened, practically usable optical glass for absorbing light is limited.
If it is less than m, the only glass material that can be used practically is fluorite. In the case of shorter wavelength ultraviolet rays or X-rays, there is no usable optical glass. In such a case,
It is completely impossible to construct a reduction projection optical system using only a refractive optical system or a catadioptric optical system.

For this reason, a so-called catadioptric reduction projection optical system in which a projection optical system is constituted only by a reflection system is disclosed in, for example, JP-A-9-213332 and JP-A-10-90602.
No. 1993. Of these, Japanese Patent Laid-Open No. 9-211
The projection optical system disclosed in JP-A-332-332 is composed of two sets of reduction optical systems each having a concave-convex concave reflection surface, and an intermediate image is formed between the two sets of reduction optical systems. I have. The projection optical system disclosed in Japanese Patent Application Laid-Open No. H10-90602 has a configuration in which two sets of four mirrors of a concave mirror, a convex mirror, a convex mirror, and a concave mirror are arranged in series, and is composed of a total of eight reflecting mirrors. And an intermediate image is formed on the way. The advantages of these optics are:
The number of reflecting surfaces becomes six or eight, and the degree of freedom of aberration correction increases. The number of reflecting surfaces naturally becomes even, so that a flat reflecting mirror only for folding is unnecessary. The reduction magnification can be shared among the respective partial optical systems, so that the burden on the partial optical systems can be reduced.

[0005]

However, in such a configuration, an intermediate image is formed on the way,
For example, when an intermediate image is formed at a position close to the reflecting surface, the temperature of the reflecting surface rises due to concentrated light and the reflecting surface is thermally deformed, and the imaging performance is deteriorated due to the thermal deformation of the reflecting surface. Fear arises.

Japanese Patent Application Laid-Open No. H11-249313 discloses a projection optical system that forms an image of an object on a predetermined surface without forming an intermediate image by using four reflecting surfaces.
With four reflecting surfaces, a large numerical aperture cannot be obtained, and a high resolution cannot be obtained.

The present invention has been made in view of such circumstances, and has a projection optical system having excellent image forming performance while suppressing the temperature rise of each reflection surface while having at least six reflection surfaces. An object of the present invention is to provide an exposure apparatus and an exposure method including an optical system.

[0008]

In order to solve the above-mentioned problems, the present invention employs the following configuration corresponding to FIGS. 1 to 3 shown in the embodiments. The projection optical system (P
L) converts the reduced image of the object on the first surface (R) to the second surface (W).
In the projection optical system formed on the first surface (R) and the second surface (R),
A first mirror pair consisting of a first reflecting mirror (M1) and a second reflecting mirror (M2) each having a reflecting surface of a predetermined shape between the second reflecting mirror (M3) and a fourth reflecting mirror (M3), Reflector (M
4) and a third mirror pair including a fifth reflecting mirror (M5) and a sixth reflecting mirror (M6) are arranged, and the first to sixth reflecting mirrors (M1 to M6) It is arranged coaxially with respect to a predetermined optical axis (AX) and has a first surface (R).
(EL) reflected from the first mirror pair in the order of the first reflecting mirror (M1) and the second reflecting mirror (M2), and the light (EL) reflected from the first mirror pair is the third reflecting mirror. (M3) and the fourth mirror (M4) are reflected in the order of the second mirror pair, and the light (EL) reflected by the second mirror pair is reflected by the fifth mirror (M5) and the sixth mirror (M5).
The third mirror pair is reflected in the order of the reflecting mirrors (M6), guided to the second surface (W), and formed on the second surface (W) without forming an intermediate image. I do.

According to the present invention, each of the six reflecting mirrors (M1 to M6) having a reflecting surface of a predetermined shape is provided between the first surface (R) and the second surface (W) with a predetermined optical axis (M). AX), and the light (EL) from the first surface (R) is reflected by each mirror pair to form an image on the second surface (W) without forming an intermediate image. can do. Thereby, the temperature rise of each reflecting surface can be suppressed, so that the occurrence of thermal deformation can be prevented. In addition, since the number of reflecting surfaces is six, a high numerical aperture can be obtained, so that a high resolving power can be obtained. Therefore, good imaging performance can be obtained. In addition, each reflecting mirror (M1 to M
6), the projection optical system (PL)
Overall compactness can be realized.

The first reflecting mirror (M1) has a concave reflecting surface, the second reflecting mirror (M2) has a concave reflecting surface, and the third reflecting mirror (M3) has a convex reflecting surface. Having a reflecting surface, the fourth
The reflecting mirror (M4) has a concave reflecting surface, the fifth reflecting mirror (M5) has a convex reflecting surface, and the sixth reflecting mirror (M6).
By having a concave reflecting surface, it is possible to adopt a configuration in which an intermediate image is not formed while having six reflecting surfaces.

At this time, the apex of the fourth reflecting mirror (M4) is arranged on the second surface (W) side from the apex of the first reflecting mirror (M1), and the apex of the third reflecting mirror (M3) and the fourth reflecting mirror (M3). With the configuration in which the apex of the sixth reflecting mirror (M6) is arranged between the apex of the mirror (M4) and the light from the first surface (R), the second surface can be formed without forming an intermediate image. (W). Further, with such a configuration, the spread of the light flux of the reflected light can be suppressed. Therefore,
The overall size of the projection optical system (PL) can be reduced.

Further, the vertex of the fifth reflecting mirror (M5) and the sixth
The configuration in which the vertex of the third reflecting mirror (M3) is arranged between the vertex of the reflecting mirror (M6) and the configuration in which an intermediate image is not formed while suppressing the spread of the luminous flux of the reflected light. be able to.

The first, third and fifth reflecting mirrors (M1, M3,
M5) are arranged such that the respective reflecting surfaces face the first surface (R), and the second, fourth and sixth reflecting mirrors (M2, M
4, M6) are arranged such that the respective reflecting surfaces face the second surface (W), so that the light from the first surface (R) is alternately reflected between the reflecting mirrors. 2 surfaces (W)
Guided to the side. In addition, with such a configuration, the distance between the first surface (R) and the second surface (W) can be reduced, and thus the distance between the first surface (R) and the second surface (W) can be reduced. The overall size of the projection optical system (PL) disposed therebetween can be reduced.

Since an aperture stop (AS) is arranged on any one of the reflecting surfaces of the first to sixth reflecting mirrors (M1 to M6), the aberration is adjusted by adjusting the aperture stop (AS). The degree of freedom of correction can be increased. That is, in addition to adjusting the shapes of the six reflecting surfaces, the aberration can be corrected by adjusting the aperture stop (AS).

At this time, among the reflecting surfaces, the incident light beam is a divergent light beam, and the aperture stop (AS) is arranged on the reflecting surface where the reflected light beam is a convergent light beam, so that good image forming performance is obtained. The aperture stop (AS) can be arranged while maintaining.

The exposure apparatus (EX) of the present invention illuminates a mask (R) with exposure light (EL) and projects an image of a pattern formed on the mask (R) through a projection optical system to a photosensitive substrate (W). ) In an exposure apparatus for projecting on the projection optical system,
A projection optical system (PL) according to any one of claims 1 to 7.

Further, according to the exposure method of the present invention, the mask (R)
An exposure method for irradiating an exposure light (EL) on a photosensitive substrate (W) based on the exposure light (EL) and forming an image of a pattern formed on a mask (R) based on the exposure light (EL). 7. A pattern image is formed on a photosensitive substrate (W) by using the projection optical system (PL) according to any one of (7).

According to the present invention, without forming an intermediate image,
Projection optical system (PL) in which thermal deformation due to light collection is prevented
Is used to perform the exposure processing, so that the image of the pattern formed on the mask (R) is formed on the photosensitive substrate with good imaging performance. Further, since this projection optical system (PL) has six reflecting surfaces, it has a high numerical aperture. Therefore, even with a fine pattern image, the photosensitive substrate (W) can be precisely formed.
Can be formed on.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the projection optical system, exposure apparatus and exposure method of the present invention will be described below with reference to the drawings. FIG. 1 is an optical path diagram of a cross section of a reflection reduction projection optical system according to an embodiment of the present invention. In FIG. 1, the width of a light beam represents only the cross section.

In FIG. 1, a projection optical system PL is disposed between a first surface R and a second surface W, and includes a first reflecting mirror M1 and a second reflecting mirror M2. A mirror pair; a second mirror pair including a third reflecting mirror M3 and a fourth reflecting mirror M4; and a third mirror pair including a fifth reflecting mirror M5 and a sixth reflecting mirror M6. This is a reflection reduction projection optical system that forms a reduced image of the upper object on the second surface W.

The first reflecting mirror M1 has a concave reflecting surface, the second reflecting mirror M2 has a concave reflecting surface, and the third reflecting mirror M3 has a convex reflecting surface. The fourth reflecting mirror M4 has a concave reflecting surface, the fifth reflecting mirror M5 has a convex reflecting surface, and the sixth reflecting mirror M6 has a concave reflecting surface. Surface. These reflecting mirrors M1 to M6 are arranged coaxially with respect to the optical axis AX of the projection optical system PL.

Of each mirror pair, the first reflecting mirror M
The first, third and fifth reflecting mirrors M3 and M5 are arranged such that their respective reflecting surfaces face the first surface R, and the second, fourth and sixth reflecting mirrors M2, M4 and M4 are provided. M6 is arranged such that each reflection surface faces the second surface W side.

Each of the reflecting mirrors M1 to M6 is arranged in series along the optical axis AX. At this time, the vertex of the fourth reflecting mirror M4 is disposed closer to the second surface W than the vertex of the first reflecting mirror M1,
The vertex of the sixth reflecting mirror M4 is disposed between the vertex of the third reflecting mirror M3 and the vertex of the fourth reflecting mirror M4. In addition, the fifth
Between the vertex of the reflecting mirror M5 and the vertex of the sixth reflecting mirror M6,
The vertex of the third reflecting mirror M3 is arranged. That is, each reflecting mirror moves from the first surface R side to the second surface W side in the second direction.
The reflecting mirror M2, the first reflecting mirror M1, the fourth reflecting mirror M4, the sixth reflecting mirror M6, the third reflecting mirror M3, and the fifth reflecting mirror M5 are arranged in this order. Accordingly, the concave portion of the fifth reflecting mirror M5 and the second surface W face each other.

Note that the vertex of the reflecting mirror is a point where the reflecting surface and the reference axis of the reflecting surface intersect, and the reference axis of the reflecting surface is the vertex of the reflecting surface and the paraxial curvature of the reflecting surface. It means the axis connecting the center.

The light EL from the first surface R is reflected by the first mirror pair in the order of the first mirror M1 and the second mirror M2, and the light reflected by the first mirror pair is reflected by the third mirror. The light reflected by the second mirror pair in the order of M3 and the fourth reflecting mirror M4 is reflected by the third mirror pair in the order of the fifth reflecting mirror M5 and the sixth reflecting mirror M6. The light is guided to the second surface W and is imaged on the second surface W.

An aperture stop AS is provided near the reflecting surface of the fourth reflecting mirror M4. The aperture stop AS has a variable aperture. The position where the aperture stop AS is arranged can be set in the vicinity of any one of the first to sixth reflecting mirrors, but the luminous flux incident on the reflecting surface diverges. It is preferable to dispose the aperture stop AS near the reflecting surface which is a light beam and the light beam reflected from the reflecting surface becomes a convergent light beam. In other words, among the respective reflection surfaces, the reflection surface of the reflection surface itself is concave, and the aperture stop AS is disposed near the reflection surface arranged upstream of the reflection surface in the optical path, such that the reflection surface is convex. . Therefore, in the present embodiment, it is preferable to dispose the aperture stop AS at a position near one of the reflecting surfaces of the fourth reflecting mirror M4 and the sixth reflecting mirror M6. That is, in the present embodiment, the light beam incident on the fourth reflecting mirror M4 from the third reflecting mirror M3 is a divergent light beam, and the light beam reflected from the fourth reflecting mirror M4 is the fifth light beam.
The light beam incident on the reflecting mirror M5 is a convergent light beam. And
The shape of each reflecting surface is set so that the degree of divergence of the divergent light beam and the degree of convergence of the convergent light beam are substantially the same.

By arranging the six reflecting mirrors M1 to M6 each having a reflecting surface as described above at a predetermined position, the light EL from the first surface R can be converted into the second image without forming an intermediate image. An image is formed on the surface W. As a result, there is no portion to be condensed in the projection optical system PL.
It is possible to suppress a rise in the temperature of each reflecting surface due to light collection.
Therefore, thermal deformation of the reflecting surface can be prevented, and good imaging performance can be obtained. In addition, since the number of reflecting surfaces is six, a high numerical aperture can be obtained, so that a high resolving power can be obtained.

Further, by arranging the reflecting mirrors M1 to M6 as described above, the spread of the reflected light from the reflecting mirrors M1 to M6 can be suppressed. Therefore,
The overall size of the projection optical system PL can be reduced. Further, since each of the reflecting mirrors M1 to M6 is arranged coaxially with respect to the optical axis AX, it is possible to further reduce the size of the projection optical system PL.

The first mirror M1, the third mirror M3, and the fifth
The reflecting mirror M5 is disposed so that each reflecting surface faces the first surface R side, and the second reflecting mirror M2, the fourth reflecting mirror M4, and the sixth reflecting mirror M6 are such that each reflecting surface is on the second surface W side. , The light EL from the first surface R is guided to the second surface W while alternately reflecting between the reflecting mirrors. And, with such a configuration, the first
Since the distance between the surface R and the second surface W can be shortened, and a flat reflecting mirror for turning back the optical path is not required, the projection optics disposed between the first surface R and the second surface W The whole system PL can be made compact, and the mounting and adjustment of the lens barrel of each of the reflecting mirrors M1 to M6 can be facilitated.

An aperture stop AS having a variable aperture is provided, and by adjusting the aperture stop AS, aberrations can be corrected, and each of the reflecting mirrors M1 to M6 can be adjusted.
The aberration can also be corrected by making the shape of the reflecting surface aspherical and arbitrarily setting this shape.
Therefore, in the present embodiment, the aberration correction can be performed not only by adjusting the shape of the reflection surface of each reflecting mirror but also by adjusting the aperture stop AS, so that aberration correction with a high degree of freedom can be performed.

Next, an exposure apparatus EX having a projection optical system PL according to the present invention will be described with reference to FIG. FIG. 2 is a configuration diagram of an exposure apparatus EX including the projection optical system PL according to the present invention. The exposure apparatus EX irradiates a reflective reticle (mask) R with exposure illumination light (exposure light) EL, and forms a partial image of a pattern formed on the reticle R through a projection optical system PL through a photosensitive substrate W. By projecting the reticle R and the photosensitive substrate W relative to the projection optical system PL in the one-dimensional direction (Y direction) while projecting the reticle R on the photosensitive substrate W, the entire pattern of the reticle R is shot on the photosensitive substrate W. The image is transferred to each of the regions by a step-and-scan method. In this embodiment, the exposure light EL has a wavelength of 5
Light in the soft X-ray region of about 15 nm (EUV light) is used. In FIG. 2, the direction of the optical axis of the projection optical system PL is defined as a Z direction, and the direction orthogonal to the Z direction and the scanning direction of the reticle R and the photosensitive substrate W is defined as a Y direction.
The direction perpendicular to the paper plane perpendicular to the YZ directions is defined as the X direction.

In FIG. 2, the exposure apparatus EX includes a light source 30
An illumination optical system 3 for illuminating a reticle R supported by a reticle stage RS with a light beam from the reticle stage RS; a projection optical system PL for projecting an image of a pattern of the reticle R illuminated with exposure light EL onto a photosensitive substrate W; Substrate stage WS supporting W
And EU as exposure light in the present embodiment
Since the V light has a low transmittance to the atmosphere, the optical path through which the EUV light passes is covered by the vacuum chamber VC and is shielded from the outside air.

The illumination optical system 3 in FIG. 2 will be described. The light source 30 has a function of supplying laser light having a wavelength in the infrared region to the visible region.
A G laser, an excimer laser, or the like can be used. This laser light is condensed by the first condensing optical system 31 and condensed on a position 32. The nozzle 33 moves the gaseous object to the position 32
, And the ejected object receives a high illuminance laser beam at the position 32. At this time, the ejected object becomes hot due to the energy of the laser light, is excited into a plasma state, and emits EUV light when transitioning to a low potential state.

An elliptical mirror 34 constituting a second condensing optical system is arranged around the position 32.
4 is positioned such that its first focal point substantially coincides with position 32. On the inner surface of the elliptical mirror 34, a multilayer film for reflecting EUV light is provided, and the EUV light reflected here is collected once at the second focal point of the elliptical mirror 34, and then collected at the third focusing point. The light travels to a parabolic mirror 35 as a collimating mirror constituting the optical optical system. The parabolic mirror 35 is positioned such that its focal point substantially coincides with the second focal position of the elliptical mirror 34, and has a multilayer film on its inner surface for reflecting EUV light.

The EUV light emitted from the parabolic mirror 35 is
In a substantially collimated state, the light goes to a reflective fly-eye optical system 36 as an optical integrator. The reflection type fly-eye optical system 36 has a first reflection element group 36a in which a plurality of reflection surfaces are integrated, and a second reflection element having a plurality of reflection surfaces corresponding to the plurality of reflection surfaces of the first reflection element group 36a. And an element group 36b. These first and second
Also, a multilayer film for reflecting EUV light is provided on a plurality of reflection surfaces constituting the reflection element groups 36a and 36b.

Collimated EU from parabolic mirror 35
The V light is wavefront divided by the first reflecting element group 36a,
EUV light from each reflecting surface is collected to form a plurality of light source images. A plurality of reflection surfaces of the second reflection element group 36b are positioned near each of the positions where the plurality of light source images are formed, and the plurality of reflection surfaces of the second reflection element group 36b are: It functions essentially as a field mirror. Thus, the reflection type fly-eye optical system 3
6 forms a large number of light source images as secondary light sources based on the substantially parallel light flux from the parabolic mirror 35. Such a reflective fly-eye optical system 36 is proposed in Japanese Patent Application No. 10-47400 by the present applicant.

In this embodiment, in order to control the shape of the secondary light source, a σ stop AS1 as a first aperture stop is provided near the second reflection element group 36b. The σ stop AS1 is formed, for example, by providing a plurality of openings having different shapes in a turret shape. Then, the σ stop control unit ASC1 controls which aperture is arranged in the optical path.

The EUV light from the secondary light source formed by the reflection type fly-eye optical system 36 travels to the condenser mirror 37 positioned so that the vicinity of the position of the secondary light source becomes the focal position. After being reflected and collected by the mirror 37, the light reaches the reticle R via the optical path bending mirror 38. These condenser mirrors 37
In addition, a multilayer film that reflects EUV light is provided on the surface of the optical path bending mirror 38. Then, the condenser mirror 37 collects EUV light emitted from the secondary light source and uniformly illuminates the reticle R.

In this embodiment, the illumination optical system 3 is used to spatially separate the optical path between the illumination light traveling toward the reticle R and the EUV light reflected by the reticle R and traveling toward the projection optical system PL. Is a non-telecentric system, and the projection optical system PL is also a reticle-side non-telecentric optical system.

On the reticle R, there is provided a reflective film composed of a multilayer film for reflecting EUV light. The reflective film has a pattern corresponding to the shape of the pattern to be transferred onto the photosensitive substrate W. ing. The EUV light reflected by the reticle R and containing the pattern information of the reticle R enters the projection optical system PL.

As described with reference to FIG. 1, the projection optical system PL has six reflecting mirrors M1 to M6.
A variable aperture stop AS as a second aperture stop is disposed near the reflection surface of the reflection mirror M4. The variable aperture stop AS is configured so that the aperture of the aperture is variable, and the aperture is variable aperture stop control unit ASC2.
Is controlled by In addition, the reflecting mirrors M1 to M6 constituting the projection optical system PL are formed by providing a multilayer film that reflects EUV light on a base material.

The EUV light reflected by the reticle R passes through the projection optical system PL, and enters a predetermined reduction magnification β (for example, | β | = 1 /
(4, 1/5, 1/6), a reduced image of the pattern of the reticle R is formed.

The reticle R is supported by a reticle stage RS movable at least along the Y direction.
The photosensitive substrate W is supported by a substrate stage WS that can move in the XYZ directions. The movements of reticle stage RS and substrate stage WS are controlled by reticle stage control unit RSC and substrate stage control unit, respectively. At the time of the exposure operation, while irradiating the reticle R with EUV light by the illumination optical system 3,
A reticle R and a photosensitive substrate W with respect to the projection optical system PL;
The projection optical system PL is moved at a predetermined speed ratio determined by the reduction magnification. Thus, the pattern of the reticle R is scanned and exposed in a predetermined shot area on the photosensitive substrate W.

In this embodiment, the σ stop AS
1. The variable aperture stop AS is preferably made of a metal such as Au, Ta, or W in order to sufficiently shield EUV light. Further, a multilayer film as a reflection film is formed on the reflection surface of each of the above-described reflection mirrors M1 to M6 to reflect EUV light. This multilayer film is formed by laminating a plurality of substances of molybdenum, ruthenium, rhodium, silicon, and silicon oxide.

Embodiments Hereinafter, numerical embodiments of the projection optical system according to the present invention will be described. FIG. 1 is an optical path diagram of a transverse section of a projection optical system PL for describing the present numerical example, and has the configuration described above.

Incidentally, each reflecting mirror M1 in this embodiment is
M6 has an aspherical shape rotationally symmetric with respect to the optical axis AX, and this aspherical shape is represented by the following equation.

[0047]

(Equation 1)

Here, Y: distance from the center tangent plane to the aspherical surface c: central curvature (central curvature in the paraxial region) r: distance from the optical axis k: conic coefficient A: fourth-order aspherical coefficient B : 6th order aspherical coefficient C: 8th order aspherical coefficient D: 10th order aspherical coefficient E: 12th order aspherical coefficient F: 14th order aspherical coefficient G: 16th order aspherical coefficient H: 18 Next-order aspheric coefficient J: 20th-order aspheric coefficient

Incidentally, the projection optical system PL of this embodiment is an EU optical system.
V light wavelength (exposure wavelength) is 13.4 nm, reduction magnification | β
Is 1/4 times, the numerical aperture NA on the image side is 0.165,
The light beam to the second surface (image surface) W is telecentric.

Tables 1 and 2 show the values of the specifications of the projection optical system PL. In Table 1, the surface number of each reflecting surface is shown at the left end. RDY indicates the radius of curvature of each optical surface, and THI indicates the surface interval between the reflecting surfaces. The RDY column indicates the approximate radius of curvature (unit: mm) of each reflecting surface, and the THI column indicates each surface interval (unit: mm). In Table 1, D0 is the distance from the first surface R (reticle surface) to the optical surface closest to the first surface R (in this case, the first reflecting mirror M1), W
D is the optical surface closest to the third surface W (in this case, the sixth reflecting mirror M
6) to the third surface (final image surface) W, β is the lateral magnification of the projection optical system when light enters the projection optical system from the first surface R side, and NA is the aperture on the third surface W side. The numbers are indicated respectively. In Table 1, the sign of the paraxial radius of curvature RDY is positive when it is convex toward the first surface R side, and the surface distance TH
The sign of I is reversed before and after the reflection surface.

Table 2 shows aspherical data of each of the reflecting mirrors M1 to M6.

[0052]

[Table 1]

[0053]

[Table 2]

With the projection optical system PL having the above-described structure, the first surface R is formed without forming an intermediate image.
Can be formed on the second surface W.

In the above embodiment, each of the reflecting mirrors M1 to M
Since the reflecting surface of No. 6 has a high-order aspherical shape that is rotationally symmetric with respect to the optical axis AX, high-order aberrations generated in each of the reflecting mirrors M1 to M6 are corrected to achieve good imaging performance. Here, in order to correct a rotationally asymmetric aberration component caused by a surface shape error of the reflecting surface of each of the reflecting mirrors M1 to M6 and an assembling error at the time of manufacturing the projection optical system PL, the rotationally symmetric aspheric surface is rotated. It may be an aspheric surface.

The present invention is also applicable to a step-and-repeat type exposure apparatus that exposes a mask pattern while the mask (reticle) and the substrate are stationary and sequentially moves the substrate in steps. Can be.

The application of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor. For example, an exposure apparatus for a liquid crystal for exposing a liquid crystal display element pattern to a square glass plate and a thin film magnetic head are manufactured. Widely applicable to an exposure apparatus.

When a linear motor is used for the substrate stage or reticle stage, either an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force may be used. The stage may be of a type that moves along a guide or a guideless type that does not have a guide.

When a plane motor is used as the stage driving device, one of the magnet unit (permanent magnet) and the armature unit is connected to the stage, and the other of the magnet unit and the armature unit is connected to the stage moving surface side. (Base).

The reaction force generated by the movement of the reticle stage may be mechanically released to the floor (ground) using a frame member, as described in Japanese Patent Application Laid-Open No. 8-166475. The present invention is also applicable to an exposure apparatus having such a structure.

The reaction force generated by the movement of the reticle stage may be mechanically released to the floor (ground) by using a frame member as described in Japanese Patent Application Laid-Open No. 8-330224. The present invention is also applicable to an exposure apparatus having such a structure.

As described above, the exposure apparatus according to the embodiment of the present invention converts various subsystems including the components described in the claims of the present application into predetermined mechanical accuracy, electrical accuracy,
It is manufactured by assembling to maintain optical accuracy. Before and after this assembly, adjustments to achieve optical accuracy for various optical systems, adjustments to achieve mechanical accuracy for various mechanical systems, and various electric systems to ensure these various accuracy Are adjusted to achieve electrical accuracy. The process of assembling the various subsystems into the exposure apparatus includes mechanical connection, wiring connection of an electric circuit, and piping connection of a pneumatic circuit between the various subsystems. It goes without saying that there is an assembling process for each subsystem before the assembling process from these various subsystems to the exposure apparatus. When the process of assembling the various subsystems into the exposure apparatus is completed, comprehensive adjustment is performed, and various precisions of the entire exposure apparatus are secured. It is desirable that the exposure apparatus be manufactured in a clean room in which the temperature, cleanliness, and the like are controlled.

As shown in FIG. 3, for a semiconductor device, a step 201 for designing the function and performance of the device, a step 202 for manufacturing a mask (reticle) based on this design step, a step 203 for manufacturing a wafer from a silicon material Wafer processing step of exposing a reticle pattern to a wafer by the exposure apparatus of the above-described embodiment.
04, a device assembling step (including a dicing step, a bonding step, and a packaging step) 205, an inspection step 206, and the like.

[0064]

According to the projection optical system of the present invention, light from the first surface is formed on the second surface without forming an intermediate image. Thereby, since there is no portion where light is condensed in the projection optical system PL, it is possible to suppress a rise in temperature of each reflecting surface due to light condensing. Therefore, thermal deformation of the reflection surface due to a temperature rise can be prevented, so that good imaging performance can be obtained. In addition, since the number of reflecting surfaces is six, a high numerical aperture can be obtained, so that a high resolving power can be obtained. Further, since the configuration is such that the spread of the reflected light from each reflecting mirror is suppressed, it is possible to realize a compact projection optical system as a whole. Further, by providing an aperture stop, aberration correction can be performed by adjusting the aperture stop, and aberration correction can also be performed by arbitrarily setting the shape of the reflecting surface of each reflecting mirror. Therefore, aberration correction with a high degree of freedom can be performed.

According to the exposure apparatus and the exposure method of the present invention,
Since an exposure process is performed using a projection optical system that prevents thermal deformation due to light collection without forming an intermediate image, an image of a pattern formed on a mask can be formed on a photosensitive substrate with good imaging performance. It is formed. Also, since this projection optical system has six reflecting surfaces, it has a high numerical aperture. Therefore, even a fine pattern can be accurately formed on the photosensitive substrate.

[Brief description of the drawings]

FIG. 1 is an optical path diagram of a cross section for explaining an embodiment of a projection optical system of the present invention.

FIG. 2 is a configuration diagram for explaining an exposure apparatus having a projection optical system according to the present invention.

FIG. 3 is a flowchart illustrating an example of a manufacturing process of a semiconductor device.

[Explanation of symbols]

 AS Aperture stop AX Optical axis EL light (exposure light) EX Exposure device M1 First reflecting mirror M2 Second reflecting mirror M3 Third reflecting mirror M4 Fourth reflecting mirror M5 Fifth reflecting mirror M6 Sixth reflecting mirror PL Projection optical system R First surface (mask, reticle) W Second surface (photosensitive substrate)

Claims (9)

[Claims] 1. A projection optical system for forming a reduced image of an object on a first surface on a second surface, wherein the first and second surfaces each have a reflecting surface of a predetermined shape between the first surface and the second surface. A first mirror pair consisting of a reflecting mirror and a second reflecting mirror, a second mirror pair consisting of a third reflecting mirror and a fourth reflecting mirror, and a third mirror pair consisting of a fifth reflecting mirror and a sixth reflecting mirror are arranged. Wherein the first to sixth reflecting mirrors are arranged coaxially with respect to a predetermined optical axis, and the light from the first surface is transmitted in the order of the first reflecting mirror and the second reflecting mirror. The light reflected by the first mirror pair, the light reflected by the first mirror pair is reflected by the second mirror pair in the order of the third reflecting mirror and the fourth reflecting mirror, and the light reflected by the second mirror pair. Reflects the third mirror pair in the order of the fifth reflecting mirror and the sixth reflecting mirror and is guided to the second surface to form an intermediate image. A projection optical system for forming an image on the second surface. 2. The projection optical system according to claim 1, wherein the first reflecting mirror has a concave reflecting surface, the second reflecting mirror has a concave reflecting surface, and wherein the third reflecting mirror has a concave reflecting surface. The mirror has a convex reflecting surface, the fourth reflecting mirror has a concave reflecting surface, the fifth reflecting mirror has a convex reflecting surface, and the sixth reflecting mirror has a convex reflecting surface.
A projection optical system, wherein the reflecting mirror has a concave reflecting surface. 3. The projection optical system according to claim 1, wherein a vertex of the fourth reflecting mirror is disposed closer to the second surface than a vertex of the first reflecting mirror, and a vertex of the third reflecting mirror is provided. A projection optical system, wherein a vertex of the sixth reflecting mirror is disposed between the first reflecting mirror and a vertex of the fourth reflecting mirror. 4. The projection optical system according to claim 1, wherein a vertex of the third reflecting mirror is located between a vertex of the fifth reflecting mirror and a vertex of the sixth reflecting mirror. A projection optical system, which is disposed. 5. The projection optical system according to claim 1, wherein each of the first, third, and fifth reflecting mirrors is such that each reflecting surface is the first reflecting mirror.
The second, fourth, and sixth reflecting mirrors are arranged so that they face each other,
A projection optical system, wherein each projection optical system is arranged so as to face a surface. 6. The projection optical system according to claim 1, wherein an aperture stop is arranged on any one of the reflecting surfaces of the first to sixth reflecting mirrors. A projection optical system characterized by the above-mentioned. 7. The projection optical system according to claim 6, wherein an incident light beam among the respective reflection surfaces is a divergent light beam,
A projection optical system, wherein the aperture stop is arranged on a reflection surface on which a reflected light beam becomes a convergent light beam. 8. An exposure apparatus for irradiating a mask with exposure light and projecting an image of a pattern formed on the mask onto a photosensitive substrate via a projection optical system, wherein the projection optical system is Item 8. An exposure apparatus comprising the projection optical system according to any one of items 7. 9. An exposure method for illuminating a mask with exposure light and forming an image of a pattern formed on the mask on a photosensitive substrate based on the exposure light. 13. An exposure method, wherein an image of the pattern is formed on the photosensitive substrate by using the projection optical system according to the above item.