JP2001185480A - Projection optical system and projection exposure apparatus having the optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection optical system having a large numerical aperture at a wavelength of 200 nm or less, particularly a soft X-ray wavelength range of 100 nm or less, and having a resolution significantly less than 50 nm, and a projection having the optical system. To provide an exposure apparatus. SOLUTION: In a projection optical system TL for projecting an image of a first surface M on a second surface W, an arc-shaped field region EA is included in a region not including the optical axis AX, and a shielding region SA is provided on a pupil surface. Have.

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 suitable for a projection exposure apparatus used for manufacturing, for example, a semiconductor element or a liquid crystal display element by a photolithography process, and a projection exposure apparatus having the optical system. More particularly, the present invention relates to a projection optical system suitable for a scanning projection exposure apparatus and having a resolution of 0.1 μm or less in an ultraviolet region.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device or the like, a pattern image formed on a photomask or a reticle (hereinafter, collectively referred to as a "reticle") is exposed to a photoresist through a projection optical system. There is used a projection exposure apparatus that performs projection exposure on a wafer or a glass plate coated with a film or the like. As the degree of integration of semiconductor elements and the like increases, the resolution required for a projection optical system used in a projection exposure apparatus has been increasing. In order to satisfy this requirement, it is necessary to shorten the wavelength of the illumination light (exposure light), increase the numerical aperture (hereinafter, referred to as “NA”) of the projection optical system, or perform both of them. . For example, the wavelength of the illumination light is 180n
When it is less than m, a high resolution of 0.1 μm or less can be achieved.

[0003]

As the wavelength of the illumination light becomes shorter, the types of glass materials that can withstand practical use due to light absorption are limited. In particular, when the wavelength is less than 180 nm, the glass material that can be used practically is limited to fluorite. Is done. Further, if the wavelength is 1
When the thickness is less than 00 nm, there is no glass material usable as a refractive lens. Therefore, it is necessary to develop an optical system using no refractive lens or an optical system using a very small number of refractive lenses.

There have been proposed various techniques for constructing a projection optical system by using a reflection type optical system that does not use any refraction lens or a reflection type optical system that uses a very small number of refraction lenses. For example, an optical system having a large aperture whose NA on the image side exceeds 0.2 is disclosed in U.S. Pat.
It is disclosed in JP-A-5,815,310 and JP-A-5,686,728.

[0005] However, the optical systems disclosed in these publications have a problem that when the image-side numerical aperture exceeds 0.3 and when, for example, radiation in the soft X-ray region having a wavelength of 100 nm or less is used, The aberration has not been sufficiently corrected. Therefore, if the above optical system is used as, for example, a projection optical system having a resolution of 30 nm or less, sufficient optical performance cannot be obtained.

The present invention has been made in view of the above problems, and has a large numerical aperture at a wavelength of 200 nm or less, particularly a soft X-ray wavelength region of 100 nm or less, and a projection optical system having a resolution significantly less than 50 nm. It is an object to provide a system and a projection exposure apparatus provided with the optical system.

[0007]

According to the present invention, there is provided a projection optical system for projecting an image on a first surface onto a second surface. And a projection optical system characterized by having a shielding area on the pupil plane.

In the present invention, the projection optical system includes a first imaging optical system for forming an intermediate image on the first surface,
A second imaging optical system for forming a final image of the first surface on the second surface based on light emitted from the intermediate image, wherein the first imaging optical system includes at least two reflection optical systems. Surface
It is preferable that the second imaging optical system has at least one reflection surface having a light passing portion. Here, the emitted light includes radiation from a hard X-ray region of about 1 nm to an infrared region of about 10 μm. Further, in the configuration according to claim 2, the first imaging optical system re-images an intermediate image of the first surface with a first sub-imaging optical system that forms an intermediate image of the first surface. A second sub-imaging optical system, wherein the second imaging optical system converts the final image of the first surface to the second surface based on light emitted from an image by the second sub-imaging optical system. It is preferable to form it on.

Further, in the present invention, it is preferable that the shielding region has a ring shape (a ring shape, a donut shape).

Further, according to the present invention, in a projection optical system for projecting an image on a first surface onto a second surface, a first imaging optical system for forming an intermediate image on the first surface, and A second imaging optical system that forms a final image of the first surface on the second surface based on the emitted light of the first imaging optical system,
It is preferable that the second imaging optical system has at least one reflecting surface having a light passing portion.

In the present invention, the projection optical system includes a first imaging optical system for forming an intermediate image on the first surface,
A second imaging optical system for forming a final image of the first surface on the second surface based on light emitted from the intermediate image, wherein the first imaging optical system has at least one positive optical system. A power reflecting surface, and at least one negative power reflecting surface, wherein the second imaging optical system includes a primary mirror provided in the vicinity of the intermediate image, and a second mirror closer to the second mirror than the primary mirror. The main mirror has a first light passing portion and a first reflecting surface of positive power (concave shape), and the sub mirror has a second light passing portion. , A second reflecting surface, and the emitted light from the intermediate image is
The radiation reflected by the second reflection surface of the secondary mirror via the first light passage portion of the primary mirror and reflected by the second reflection surface of the secondary mirror is the first reflection of the primary mirror. Reflected on the surface,
It is preferable that the radiation reflected by the first reflection surface of the primary mirror forms the final image on the second surface via the second light passage portion of the secondary mirror. The power of the reflection surface is the reciprocal of the focal length of the reflection surface.

In the present invention, it is desirable that all the optical elements constituting the projection optical system are reflection surfaces.

In the present invention, the projection optical system includes a first imaging optical system for forming an intermediate image on the first surface;
A second imaging optical system for forming a final image of the first surface on the second surface based on radiation light from the intermediate image, wherein the first imaging optical system has at least one Preferably, the projection optical system has two refractive lens components, and the projection optical system is an optical system that is telecentric on the first surface side and the second surface side.

Further, in the present invention, it is desirable that the optical axes of all the optical elements constituting the projection optical system are located on the same straight line.

In the present invention, the projection optical system includes a first imaging optical system for forming an intermediate image on the first surface,
A second imaging optical system that forms a final image of the first surface on the second surface based on light emitted from the intermediate image, and a telecentric optical system on the second surface side. It is preferable that a shielding member for forming the shielding region is disposed near the pupil plane in the first imaging optical system.

In the present invention, the projection optical system includes a first imaging optical system for forming an intermediate image on the first surface,
A second imaging optical system that forms a final image of the first surface on the second surface based on light emitted from the intermediate image, wherein the first imaging optical system is located near a pupil plane. It has a reflecting mirror arranged, the reflecting surface of the reflecting mirror may have a reflecting area having a predetermined reflectance and a low reflecting area having a lower reflectance than the reflectance of the reflecting area. desirable. Here, the low reflectivity area is an area that does not reflect emitted light (non-reflective area).
Is also included. Thus, the shape of the shielding area on the pupil plane is substantially the same between the pupil planes corresponding to the emitted light from any position in the viewing area.

Further, the present invention provides a projection exposure apparatus for projecting and transferring an image of a mask on which a predetermined pattern is formed onto a photosensitive substrate, wherein a radiation source for supplying radiation of a predetermined wavelength;
A projection optical system according to any one of claims 1 to 10, a first stage for positioning the mask on the first surface,
And a second stage for positioning the photosensitive substrate on the second surface.

In the present invention according to claims 1 to 10, it is preferable to adopt any one of the following constitutions (1) to (5). (1) The projection optical system preferably has at least two aspherical reflecting surfaces. (2) It is preferable that a field stop is provided near the intermediate image. (3) The projection optical system preferably has a reflection surface, and the substrate on which the reflection surface is formed has a linear expansion coefficient of 3
It is preferably at most ppm / ° C. (4) Preferably, the projection optical system includes a primary mirror having a first light passing portion and a first reflecting surface, and a secondary mirror having a second light passing portion and a second reflecting surface. It is preferable that an aperture stop is provided between the secondary mirror and the secondary mirror, and the light emitted through the first light passage portion of the primary mirror is transmitted to the secondary mirror of the secondary mirror.
Radiation light reflected by a reflection surface and reflected by the second reflection surface of the secondary mirror is reflected by a first reflection surface of the primary mirror, and radiation light reflected by the first reflection surface of the primary mirror is It is preferable that the final image is formed on the second surface via the second light passage portion of the sub mirror. (5) It is preferable to include a primary mirror having a first light passage portion and a first reflection surface and a secondary mirror having a second light passage portion and a second reflection surface, and between the primary mirror and the secondary mirror. Is preferably provided with a shielding member.

Further, in the invention according to claim 5,
It is preferable that the first light passage portion is formed in a region surrounded by the first reflection surface region, and the second light passage portion is formed in a region surrounded by the second reflection surface region.

According to another aspect of the present invention, there is provided a projection optical system for projecting an image on a first surface onto a second surface, wherein a first light passing portion and an area surrounding the first light passing portion are provided. A primary mirror having a first reflecting surface formed thereon; and a sub-mirror having a second light passing portion and a second reflecting surface formed in a region surrounding the second light passing portion. The second reflection surface forms at least three optical paths between the first and second reflection surfaces, and the first and second light passage portions define an optical axis formed by the first and second reflection surfaces. The projection optical system is formed at a position that does not include the projection optical system.

According to still another aspect of the present invention,
A projection optical system for projecting an image of the first surface onto the second surface, the primary mirror having a first light passage portion and a first reflection surface formed in a castle surrounding the first light passage portion; A secondary mirror having a second light passage portion and a second reflection surface formed in a region surrounding the second light passage portion, wherein the first and second reflection surfaces are the first and second reflection surfaces; Is formed at a position including the optical axis formed by the light-emitting device, and the first and second light passage portions are formed at positions not including the optical axis.

In any one of the above structures, it is preferable that a reflecting mirror having a reflecting surface at a position not including the optical axis is further provided. In this case, it is preferable that the reflecting mirror is disposed on the first surface side of the primary mirror and the secondary mirror.

[0023] In any one of the above structures, a shielding member may be provided for shielding radiation light passing through the first and second light passage portions without passing through the first and second reflection surfaces. Is preferred.

The present invention is also a projection exposure apparatus for projecting and transferring an image of a mask on which a predetermined pattern is formed on a photosensitive substrate, comprising: a radiation source for supplying radiation of a predetermined wavelength;
A projection optical system according to any one of claims 1 to 10, or a first stage for positioning the mask on the first surface, and the photosensitive substrate on the second surface. And a second stage for positioning.

In the above-mentioned projection exposure apparatus, it is preferable to adopt any one of the following constitutions (6) to (10). (6) Preferably, the mask is a reflective mask that selectively reflects the emitted light. (7) In the constitution of claim 11 or (6), it is preferable that the radiation source supplies a radiation light of 200 nm or less. (8) In the configuration of the above (7), the radiation source is 16
It is preferable to supply radiation light of 0 nm or less. (9) In the configuration of the above (8), the radiation source is 10
It is preferable to supply radiation light of 0 nm or less. (10) In any one of claims 11 or (6) to (9), the first stage is provided so as to be movable in a direction crossing a longitudinal direction of the arc-shaped field of view, and the second stage is provided with: It is preferable to be provided so as to be movable in a direction crossing the longitudinal direction of the final image of the arc-shaped field of view.

Further, the present invention is a projection exposure method for projecting and transferring an image of a mask on which a predetermined pattern is formed on a photosensitive substrate, wherein the method comprises the steps of: Preparing a projection optical system according to any of the above, disposing the mask on the first surface of the projection optical system, disposing the photosensitive substrate on the second surface of the projection optical system,
A projection exposure method, characterized in that radiation light of a predetermined wavelength is supplied to the mask disposed on a surface, and an image of the mask is formed on the photosensitive substrate disposed on the second surface.

In the above projection exposure method, the following (1)
It is preferable to adopt any one of the constitutions 1) to (16). (11) It is preferable that the emitted light is reflected by the mask and guided to the projection optical system. (12) It is preferable to supply a radiation having a wavelength of 200 nm or less to the mask. (13) In the above (12), the mask has a wavelength of 16
It is preferable to supply radiation light of 0 nm or less. (14) In the above (13), the wavelength of 10
It is preferable to supply radiation light of 0 nm or less. (15) In any of the above, it is preferable to perform the projection exposure while changing the relative position between the photosensitive substrate and the projection optical system. (16) In (15), preferably, the direction in which the position is changed is a direction crossing the longitudinal direction of the arc-shaped field of view of the projection optical system.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First Embodiment A schematic configuration of a projection optical system according to a first embodiment of the present invention will be described with reference to FIG. The projection optical system TL is a projection optical system suitable for a scanning projection exposure apparatus to be described later, and includes a first imaging optical system K1 for forming an intermediate image I1 of a pattern of the mask M as a first surface, and an intermediate optical system K1. A second imaging optical system K2 for forming a final image I2 of the pattern of the mask M on a wafer W as a photosensitive substrate at a reduced magnification based on the radiation light from the image I1. The projection optical system is an optical system that is telecentric on the wafer side.

The first imaging optical system K1 includes a reflecting mirror M1 having a positive power (concave shape) and a reflecting mirror M having a negative power (convex shape).
2, a negative power convex mirror M3, a positive power concave mirror M4
have. Light emitted from the mask M is sequentially reflected via these four reflecting mirrors M1 to M4, and an intermediate image I1 of the pattern of the mask M is formed. Further, the second imaging optical system K2 includes a main mirror MS having a positive power provided near the intermediate image I2, and a sub-mirror MF provided on the wafer W side of the main mirror MS. The primary mirror MS has a first opening AP1 and a reflective surface having a positive power (concave shape). The secondary mirror MF has a second opening AP2.

The radiated light from the intermediate image I1 is reflected by the reflecting surface of the sub mirror MF through the first opening AP1 of the main mirror MS.
The radiation reflected by the reflecting surface of the secondary mirror MF is the first radiation of the primary mirror MS.
The radiated light reflected by the reflection surface and reflected by the first reflection surface of the primary mirror MS is transmitted through the second opening AP2 of the secondary mirror MF to the wafer W.
A final image I2 is formed thereon.

In order to form the intermediate image I1, the first imaging optical system K1 needs to have at least one concave mirror M4. By having at least one convex mirror M3, it is possible to adjust the Petzval sum of the entire optical system to be zero.

The exposure area is an arc-shaped area centered on the optical axis AX and having a radius of 15.0 to 15.6 mm.
A field size of 16 mm width can be used in the scan direction indicated by the middle arrow SC.

Since the projection optical system according to this embodiment is a reflection type optical system, it is necessary to separate the optical path between the forward path and the return path. Therefore, first, the separation of the reciprocating optical path will be described.
The exposure area on the mask M of the projection optical system is shown in FIG.
This is an off-axis arc-shaped region EA that does not include the optical axis AX as shown in FIG. Then, in the first imaging optical system K1,
Using this off-axis exposure area, so-called OFF / AX
An IS type round-trip optical path separation is performed. The primary mirror MS and the secondary mirror MF of the second imaging optical system K2 have the first opening AP1 and the second opening AP2, respectively, as described above. In the second imaging optical system K2, a so-called center shield type reciprocating optical path separation is performed using these openings. Further, in order to remove unnecessary radiation light directly reaching the wafer W from the first and second openings AP1 and AP2, a ring-shaped shielding area S shown in FIG.
A is provided.

If the area of the shielding area SA is large, the imaging performance is deteriorated. Therefore, it is desirable to reduce the shielding area as much as possible. For this reason, the optical system passes through the opening at the position of the image conjugate where the opening of the light beam of the radiated light is small, and is reflected by the reflection surfaces of the primary mirror MS and the sub-mirror MF at the position where the light beam opening is large. Deploy. Further, when the opening is arranged at the position of the image conjugate, the effective area of the opening has an arc shape. For this reason, as shown in FIG. 2B, by making the shielding area SA in the pupil ring-shaped, the shielding area can be reduced. Further, by making the shielding area SA ring-shaped, it is possible to use the radiation light passing near the center of the pupil plane, so that the ratio of blocking the diffracted light generated by the mask M is reduced, and the 0th-order diffracted light and ± 1st-order Since the ratio of interference with the folded light increases, deterioration of the contrast of the final image I2 can be prevented.

With the above configuration, it is possible to obtain a resolution of 30 nm or less while keeping the area of the shielding area SA in the pupil small. Further, since the present projection optical system is an optical system that is telecentric on the wafer W side, image distortion due to displacement in the optical axis direction due to deflection of the wafer or the like can be reduced.

Further, it is desirable that the shielding area SA of the convex mirror M3 near the pupil plane in the first imaging optical system K1 shields emitted light by disposing a shielding member. With this configuration, the position and size of the shielding area SA can be made substantially the same with respect to the light emitted from the entire screen. Therefore, the imaging performance can be made substantially the same in the screen. In addition,
By forming a reflection region having a predetermined reflectance and a low reflection region having a reflectance lower than the reflectance of the reflection region on the reflection surface of the convex mirror M3, the shielding region SA can be formed. More preferably, it is desirable that the reflectivity of this low-reflection region is almost zero or extremely low.

The projection optical system has six aspherical surfaces (ASP1 and the like in lens data to be described later). The resolution can be improved by introducing an aspherical surface.
Further, a field stop S1 is provided near the intermediate image I1 formed by the first imaging optical system K1. The stray light generated on the mask M side by the field stop S1 can be prevented from reaching the wafer W. In addition, all the optical elements constituting the projection optical system are reflection surfaces. Thus, a finer pattern image formed on the mask M can be projected and transferred onto the wafer W using, for example, soft X-rays having a wavelength of 100 nm or less as exposure light. Further, a shielding member may be provided near the optical axis AX between the primary mirror MS and the secondary mirror MF.

The coefficient of linear expansion of the substrate on which the reflection surface is formed is 3 ppm / ° C. or less. Thus, it is possible to prevent the shape of the reflecting mirror from changing during the projection exposure, and to prevent the imaging performance from deteriorating. Further, the optical axes AX of all the optical elements constituting the projection optical system are located on the same straight line. As a result, the projection optical system can be easily assembled or adjusted, and sufficient imaging performance can be obtained. in addition,
By arranging the aperture stop S2 in the reciprocating optical path between the primary mirror MS and the secondary mirror MF in the second imaging optical system K2, the numerical aperture of the projection optical system can be made variable.

Table 1 shows the specification values of the projection optical system according to the first embodiment. In Table 1, the leftmost number is the mask M
The order of the reflection surface (lens surface) from the (first surface) side, r is the radius of curvature of the reflection surface (lens surface), and d is the distance from the reflection surface (lens surface) to the next reflection surface (lens surface). The interval on the optical axis, β is the magnification of the entire projection optical system, and NA is the wafer side (second
The numerical aperture on the surface side) and λ indicate the reference wavelength.
The sign of the radius of curvature r is positive when the center of curvature of the reflection surface (lens surface) is located on the second surface side of the reflection surface (lens surface), and the curvature of the reflection surface (lens surface). When the center is located on the first surface side with respect to the reflection surface (lens surface), the value is negative. Also, the sign of the surface distance d is assumed to have its sign reversed each time radiation is reflected on the reflecting surface.

Further, ASP in the lens data indicates an aspherical surface. In each embodiment, the height of the aspheric surface in the direction perpendicular to the optical axis is y, and the distance (sag amount) along the optical axis from the tangent plane at the vertex of the aspheric surface to a position on the aspheric surface at the height y. Is Z, the curvature (= 1 / radius of curvature) is c, the conic coefficient is K, and the n-th order aspherical coefficient is A to G.

[0042]

[Number 1] ^{Z = (c.y 2) / [} 1+ {1- (1 + K) · c 2
^{y 2} 1/2] + A ·} y 4 + B · y 6 + C · y 8 + D · y 10 + E
・ Y ¹² + F ・ y ¹⁴ + G ・ y ¹⁶

In the following, the same reference numerals as those of the present embodiment are used in the specification values of all the embodiments. Here, mm can be used as an example of a unit of the radius of curvature r and the interval d on the optical axis in the specification values of each embodiment.

[0044]

(Overall specifications) | β | = 1/6 NA = 0.4 λ = 13.4 nm (lens data) Surface number r d Part number Aspherical surface number Object plane ∞ (flat) 229.7827 1 -14490.6822- 81.8895 M1 (ASP1) 2 -952.9808 101.1397 M2 (ASP2) 3 232.5288 -212.2304 M3 (ASP3) 4 370.8704 602.3987 M4 (ASP4) 5 778.9512 616.013 (ASP5) 6 1853.2366 -616.013 MF (ASP6) 7 778.9512 616.013 8 MS (ASP5) 8 1853.2366 10.000 (ASP6) Image plane ∞ (plane) (Aspherical coefficient) ASP1 K = 0.0 A = -3.777519 × 10 ^-9 B = + 4.73841 × 10 ^-13 C = -1.29002 × 10 ^-16 D = + 2.36639 × 10 ^-20 E = -2.61697 × 10 ^-24 F = + 1.61937 × 10 ^-28 G = -4.29843 × 10 ^-33 ASP2 K = 0.0 A = + 1.61875 × 10 ^-9 B = + 5.62543 × 10 ^-13 C = -4.90434 × 10 ^-17 D = + 5.45619 × 10 ^-20 E = -2.48455 × 10 ^-23 F = + 5.68776 × 10 ^-27 G = -5.27294 × 10 ^-31 ASP3 K = 0.0 A = -5.74815 × 10 ^-8 B = + 6.88376 × 10 ^-12 C = + 2.00960 × 10 ^-15 D = -2.96733 × 10 ^-17 E = + 1.11935 × 10 ^-19 F = -2.18345 × 10 ^-22 G = + 1.82877 × 10 ^-25 ASP4 K = 0.0 A = -4.61168 × 1 ^{0 -10 B = -2.64132 × 10 -15} C = -2.21826 × 10 -20 D = + 2.49734 × 10 -25 E = -2.31176 × 10 -29 F = + 8.13793 × 10 -34 G = -1.29461 × 10 - ³⁸ ASP5 K = 0.0 A = -4.67711 × 10 ^-11 B = + 8.24334 × 10 ^-17 C = + 1.57264 × 10 ^-22 D = -2.45315 × 10 ^-29 E = + 6.27355 × 10 ^-33 F = -6.45388 × 10 ^-38 G = + 3.10016 × 10 ^-43 ASP6 K = 0.0 A = + 2.15021 × 10 ^-9 B = + 9.30299 × 10 ^-15 C = + 6.80563 × 10 ^-20 D = + 1.03608 × 10 ^-24 E =- 5.84000 × 10 ^-29 F = + 3.81817 × 10 ^-33 G = -9.15374 × 10 ^-38 FIG. 3 shows the lateral view of the projection optical system according to the present embodiment in the meridional direction (tangential direction) and the missing spherical direction (sagittal direction). This shows aberration (coma aberration). In the figure, y indicates the image height. The same reference numerals as in the present embodiment are used in the various aberration diagrams of all the embodiments below. As is clear from the aberration diagrams, the projection optical system of this embodiment corrects aberrations in a well-balanced manner over the entire exposure area. The exposure wavelength can be used at any wavelength.
Sufficient resolution can be obtained even with soft X-rays of about 3 nm.

Generally, the resolution W of the projection optical system is expressed by the following equation.

W = k · λ / NA The coefficient k has been achieved to be 0.5 or less at the current technical level. Therefore, in this embodiment, a resolution of 20 nm or less can be obtained.

(Second Embodiment) FIG. 4 is a view showing a schematic configuration of a projection optical system according to a second embodiment. The present projection optical system is a projection optical system suitable for a scanning type projection exposure apparatus.
Two intermediate images I1 and I of the pattern of the mask M which is one surface
1 ', a first imaging optical system K1 for forming
And a second imaging optical system K2 for forming a final image I2 of the pattern of the mask M on the wafer W as a photosensitive substrate at a reduced magnification based on the radiation light from 1 '. Here, the first imaging optical system further includes a first sub-imaging optical system that forms a first intermediate image I1, and a second sub-imaging optical system that forms a second intermediate image I1 '. are doing. Further, I1 of the two intermediate images is formed in the first imaging optical system K1.
Further, this projection optical system is a telecentric optical system on the wafer side, and the optical axes of all the optical elements constituting the projection optical system are located on the same straight line AX.

The first imaging optical system K1 has a reflecting mirror M1 having a positive power (concave shape) and a reflecting mirror M having a negative power (convex shape).
2, a positive power (concave shape) reflecting mirror M3 and M4, a negative power (convex shape) reflecting mirror M5, and a positive power (concave shape) reflecting mirror M6. Radiation light from the mask M is reflected via the reflecting mirrors M1 and M2, and a first intermediate image I1 of the pattern of the mask M is formed. Then, the radiated light from the first intermediate image I1 is sequentially reflected via the reflecting mirrors M3 to M6, and a second intermediate image I1 'is formed.

The second imaging optical system K2 is provided with a positive power (concave) primary mirror MS provided in the vicinity of the second intermediate image I1 ', and provided on the wafer W side of the primary mirror MS. And the secondary mirror MF. The primary mirror MS has a first opening AP1 and a reflective surface having a positive power (concave shape). The secondary mirror MF has a second opening AP2.

The radiation light from the second intermediate image I1 'is reflected by the reflection surface of the secondary mirror MF via the first opening AP1 of the primary mirror MS, and is reflected by the reflection surface of the secondary mirror MF. Is the primary mirror M
The radiation reflected by the first reflection surface of S and reflected by the first reflection surface of the primary mirror MS forms a final image I2 on the wafer W via the second opening AP2 of the secondary mirror MF.

The exposure area is an arc area having a radius of 17.4 to 18.0 mm centered on the optical axis AX.
A field size of 22 mm width can be used in the scanning direction indicated by the arrow SC in the middle.

The shielding area SA is provided on the reflecting mirror M1. The shape of the shielding area, the method of separating the reciprocating optical path, and the like in the present embodiment are the same as those in the first embodiment, and thus description thereof will be omitted. In the present embodiment, the first imaging optical system K1 is turned off by the first and second two sub-imaging optical systems.
AXIS type optical path separation is performed, and one second imaging optical system K
In 2, a center-shielded optical path separation is performed. However, the present invention is not limited to this.
It is also possible to perform a center-shielded optical path separation using two optical systems.

Table 2 shows specification values of the projection optical system according to the second embodiment. Note that the symbols in Table 2 have the same definitions as in Table 1, and the aspheric ASP is represented by the above equation.

[0054]

[Table 2] (Overall specifications) | β | = 1/6 NA = 0.55 λ = 13.4 nm (Lens data) Surface number r d Part number Aspherical surface number Object plane 6.6 (plane) 746.6105 1 -723.0529- 440.5503 M1 (ASP1) Aperture 2 -1745.5483 762.3215 M2 (ASP2) 3 -3209.6344 -402.0086 M3 (ASP3) 4 1082.6683 580.5244 M4 (ASP4) 5 201.6806 -353.5180 M5 (ASP5) 6 502.6918 637.3296 M6 (ASP6) 7 644.8260 501.0113 (ASP7 ) 8 1895.6942 -501.0113 MF (ASP8) 9 644.8260 501.0113 MS (ASP7) 10 1895.6942 12.0000 (ASP8) Image plane ∞ (plane) (aspheric coefficient) ASP1 K = 0.0 A = -1.00941 × 10 ^-10 B = -3.38154 × 10 ^-16 C = -7.93150 × 10 ^-20 D = + 2.23178 × 10 ^-23 E = -2.13046 × 10 ^-27 F = 0.0 G = 0.0 ASP2 K = 0.0 A = -2.11134 × 10 ^-9 B = + 1.83710 × 10 ^-14 C = -2.43647 × 10 ^-18 D = + 1.65197 × 10 ^-22 E = -8.27104 × 10 ^-27 F = 0.0 G = 0.0 ASP3 K = 0.0 A = -4.06226 × 10 ^-10 B = -1.69785 × 10 ^-15 C = + 1.94147 × 10 ^-20 D = -1.12776 × 10 ^-25 E = + 2.62277 × 10 ^-31 F = 0.0 G = 0.0 ASP4 K = 0.0 A = -1.97872 × 10 ^-10 B =- 6.72995 × 10 ^-16 C = -1.23672 × 10 ^-21 D = + 4.10935 × 10 ^-27 E = -3.86642 × 10 ^-32 F = 0.0 G = 0.0 ASP5 K = 0.0 A = -1.19524 × 10 ^-8 B = + 3.97155 × 10 ^-13 C = + 4.27744 × 10 ^-17 D = -2.22397 × 10 ^-20 E = + 5.37147 × 10 ^-25 F = 0.0 G = 0.0 ASP6 K = 0.0 A = + 3.37816 × 10 ^-11 B = + 1.17850 × 10 ^-16 C = + 1.24652 × 10 ^-21 D = -6.08129 × 10 ^-27 E = + 2.39759 × 10 ^-31 F = -4.01656 × 10 ^-37 G = 0.0 ASP7 K = 0.0 A = + 6.24436 × 10 ^-11 B = + 1.99597 × 10 ^-16 C = + 5.07446 × 10 ^-22 D = + 1.55185 × 10 ^-27 E = + 5.76561 × 10 ^-34 F = + 2.38959 × 10 ^-38 G = 0.0 ASP8 K = 0.0 A = + 2.63882 × 10 ^-9 B = 1.333848 × 10 ^-14 C = + 1.10810 × 10 ^-19 D = + 9.23515 × 10 ^-25 E = + 1.67508 × 10 ^-29 F = + 1.05644 × 10 ^-34 G = 0.0 FIG. 5 is a lateral aberration diagram of the optical system according to the second example. As is clear from the figure, it is understood that the aberration is corrected in a well-balanced manner in all the exposure regions. The exposure wavelength can be any wavelength, but sufficient resolution can be obtained even with soft X-rays of about 13 nm. According to the above-described formula of the resolution W, in this embodiment, a resolution of 12 nm or less is obtained.

(Third Embodiment) FIG. 5 is a diagram showing a schematic configuration of a projection optical system according to a third embodiment. This projection optical system is a projection optical system suitable for a scanning type projection exposure apparatus.
When using exposure light of 00 to 200 nm, at least one refraction lens component L1 is provided in the first imaging optical system, and further, by using a transmission type mask, both the mask M side and the wafer W side are optically telecentric. System. Thereby, even when the position of the mask M, the wafer W, or both of them is shifted in the optical axis direction, image distortion can be reduced.

The projection optical system TL includes a first imaging optical system K1 for forming two intermediate images I1 and I1 'of the pattern of the mask M as the first surface, and radiation light from the intermediate image I1'. And a second imaging optical system K2 for forming a final image I2 of the mask M on the wafer W as a photosensitive substrate at a reduced magnification based on Here, the first imaging optical system K1 further includes a first sub-imaging optical system that forms a first intermediate image I1,
And a second sub-imaging optical system for forming a second intermediate image I1 '. Further, I1 of the two intermediate images is formed in the first imaging optical system K1. Then, the main projection optical system TL
Are positioned on the same straight line AX.

The first imaging optical system K1 comprises a positive power lens component L1 made of fluorite, a positive power (concave) reflecting mirror M1, a negative power (convex) reflecting mirror M2, and a positive power (concave). Shape reflector M3 and M4, negative power (convex shape) reflector M5, positive power (concave shape) reflector M6
have. The light emitted from the mask M has a lens component L
1 and is reflected via the reflecting mirrors M1 and M2 to form a first intermediate image I1 of the pattern of the mask M. Then, the radiation light from the first intermediate image I1 is reflected by the reflection mirrors M3 to M3.
6, and a second intermediate image I1 'of the pattern of the mask M is formed.

The second imaging optical system K2 includes a positive power primary mirror MS provided in the vicinity of the second intermediate image I1 'and a secondary mirror MF provided closer to the wafer W than the primary mirror MS. It is composed of And the primary mirror MS is provided with the first opening AP.
1 and a reflective surface of positive power (concave shape).
The secondary mirror MF has a second opening AP2.

The radiation light from the second intermediate image I1 'is reflected by the reflection surface of the secondary mirror MF via the first opening AP1 of the primary mirror MS, and is reflected by the reflection surface of the secondary mirror MF. Is the primary mirror M
The radiation reflected by the first reflection surface of S and reflected by the first reflection surface of the primary mirror MS forms a final image I2 on the wafer W via the second opening AP2 of the secondary mirror MF.

The shielding area SA is provided on the reflecting mirror M1. Since the shape of the shielding area, the method of separating the reciprocating optical path, and the like in the present embodiment are the same as those in the first and second embodiments, description thereof will be omitted.

The exposure area is an arc-shaped area having a radius of 18.0 to 19.0 mm centered on the optical axis AX.
A field size of 20 mm width can be used in the scanning direction indicated by the arrow SC in the middle.

Table 3 shows the specification values of the projection optical system according to the third embodiment. The symbols in Table 3 have the same definitions as in Table 1, and the aspheric ASP is represented by the above-described equation.

[0063]

[Table 3] (Overall specifications) | β | = 1/5 NA = 0.6 λ = 157.6 nm (Lens data) Surface number r d Part number Aspherical surface number Object plane ∞ (plane) 263.4565 1 2479.0687 40.0000 ( ASP1) 2 -383.5450 565.2289 3 -887.4658 -439.0230 M1 (ASP2) 4 -2841.3370 722.7922 M2 (ASP3) 5 -2891.3039 -379.5252 M3 (ASP4) 6 1110.0721 586.4748 M4 (ASP5) 7 227.0279 -349.3936 M5 (ASP6) 8 501.9045 624.7526 M6 (ASP7) 9 643.9023 501.4658 (ASP8) 10 1840.0726 -501.4568 MF (ASP9) 11 643.9023 501.4568 MS (ASP8) 12 1840.0726 12.0189 MF (ASP9) Image plane ∞ (flat) (aspheric coefficient) ASP1 K = 0.0 A = + 2.30448 × 10 ^-9 B = + 1.13165 × 10 ^-13 C = -1.39325 × 10 ^-18 D = + 6.71757 × 10 ^-23 E = -1.78015 × 10 ^-28 F = 0.0 G = 0.0 ASP2 K = 0.0 A =- 9.00367 × 10 ^-12 B = -1.70544 × 10 ^-15 C = + 2.22076 × 10 ^-19 D = -2.01303 × 10 ^-23 E = + 7.12282 × 10 ^-28 F = 0.0 G = 0.0 ASP3 K = 0.0 A =- 6.84682 × 10 ^-10 B = + 2.67262 × 10 ^-14 C = + 2.74 126 × 10 ^-19 D = + 8.28 256 × 10 ^-24 E = -9.54339 × 10 ^-28 F = 0.0 G = 0.0 ASP4 K = 0.0 A = -2.08860 × 10 ^-10 B = + 1.31172 × 10 ^-15 C = + 1.84845 × 10 ^-20 D = -4.08467 × 10 ^-25 E = + 2.36681 × 10 ^-30 F = 0.0 G = 0.0 ASP5 K = 0.0 A = -7.33327 × 10 ^-11 B = + 6.71066 × 10 ^-16 C = + 1.15484 × 10 ^-21 D = -3.80746 × 10 ^-26 E = + 2.79655 × 10 ^-31 F = 0.0 G = 0.0 ASP6 K = 0.0 A = -5.25543 × 10 ^-9 B = -3.16151 × 10 ^-12 C = -2.62060 × 10 ^-16 D = -3.35651 × 10 ^-20 E = -2.91797 × 10 ^-24 F = 0.0 G = 0.0 ASP7 K = 0.0 A = + 1.44360 × 10 ^-11 B = -2.14462 × 10 ^-16 C = -1.67798 × 10 ^-21 D = + 9.06834 × 10 ^-27 E = -7.63759 × 10 ^-32 F = + 2.25607 ^{× 10 -37 G = 0.0 ASP8 K} = 0.0 A = + 6.51659 × 10 -11 B = + 2.13530 × 10 -16 C = + 5.23678 × 10 -22 D = + 1.82979 × 10 -27 E = -1.14243 × 10 - ³³ F = + 3.10978 × 10 ^-38 G = 0.0 ASP9 K = 0.0 A = + 2.77031 × 10 ^-9 B = + 1.70548 × 10 ^-14 C = + 1.37306 × 10 ^-19 D = + 1.89384 × 10 ^-24 E = -5.47709 × 10 ^-33 F = + 7.47324 × 10 ^-34 G = 0.0 FIG. 7 is a lateral aberration diagram of the optical system according to the third example. In the aberration diagram, the solid line represents the reference wavelength (λ = 157.6n).
m), the dotted line is λ = 157.601 nm, and the dashed line is λ =
157.599 nm is shown. The projection optical system according to the present embodiment is designed at an exposure wavelength λ = 157.6 nm.
It can respond to exposure light of 0 nm. The refractive index of fluorite is n
Is n = 1.555923 at λ = 157.6 nm
8, and dn / dλ = −2.4 × 10 ⁻¹⁰ . As is clear from the figure, it is understood that the aberration is corrected in a well-balanced manner in all the exposure regions in the range of 157 nm ± 1 ppm.

(Fourth Embodiment) FIG. 8 is a diagram schematically showing the overall configuration of a projection exposure apparatus having a projection optical system according to each of the above embodiments of the present invention. In FIG. 8, Z is parallel to the optical axis AX of the projection optical system TL that constitutes the projection optical system.
The X-axis is set in the plane perpendicular to the optical axis AX, and the X-axis is set parallel to the plane of FIG. 8, and the Y-axis is set perpendicular to the plane of FIG. In addition, a mask M is arranged on the object surface of the projection optical system TL as a projection master on which a predetermined circuit pattern is formed.
On the image plane L, a wafer W coated with a photoresist as a substrate is arranged.

The radiated light emitted from the light source 1 uniformly illuminates the mask M on which a predetermined pattern is formed via the illumination optical system 2. In the optical path from the light source 1 to the illumination optical system 2, one or a plurality of bending mirrors for changing the optical path as necessary are arranged.

The illumination optical system 2 includes a fly-eye lens or an internal reflection type integrator for uniformizing the illuminance distribution of the exposure light, an optical integrator for forming a surface light source of a predetermined size and shape, and a mask M. It has an optical system such as a variable field stop (reticle blind) for defining the size and shape of the illumination area above, and a field stop imaging optical system that projects an image of the field stop onto a mask.

The mask M is provided via the reticle holder 4
The reticle stage 5 is held parallel to the XY plane. A pattern to be transferred is formed on the mask M, and the entire pattern area is illuminated with light from the illumination optical system 2. The reticle stage 5 can be moved two-dimensionally along the mask plane (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are measured by an interferometer 7 using a mask moving mirror 6. And the position is controlled.

The light from the pattern formed on the mask M forms a mask pattern image on the wafer W as a photosensitive substrate via the projection optical system TL. Projection optical system TL
Is an aperture stop S2 having a variable aperture near the pupil position (FIG. 1).
) And are substantially telecentric on the mask M side and the wafer W side.

The wafer W is transferred via the wafer holder 10
It is held on the wafer stage 11 in parallel with the XY plane. Then, a pattern image is formed in an exposure region having a substantially similar shape to the illumination region on the mask M.

The wafer stage 11 can be moved two-dimensionally along the wafer surface (that is, the XY plane) by the action of a drive system (not shown), and its position coordinate is the interferometer 13 using the wafer moving mirror 12. And the position is controlled.

As described above, the viewing area (illumination area) on the mask M and the projection area (exposure area) on the wafer W defined by the projection optical system TL are rectangular shapes having short sides along the X direction. It is. Therefore, the mask 3 and the wafer W are aligned using the drive system and the interferometers (7, 13) and the like, and the wafer W is positioned on the image forming plane of the projection optical system using an auto focus / auto leveling system (not shown). I do. Then, by moving (scanning) the mask stage 5 and the wafer stage 11 and thus the mask M and the wafer W synchronously (scanning) along the short side direction of the rectangular exposure region and the illumination region, that is, the X direction. On the W, a mask pattern is scanned and exposed on a region having a width equal to the long side of the exposure region and a length corresponding to the scanning amount (movement amount) of the wafer W.

As the light source, in the first and second embodiments, an SOR or laser plasma X-ray source that supplies radiation light (soft X-ray) having a wavelength of about 13 nm can be applied. Also,
The wavelength does not matter because it is a total reflection system. Therefore, hard X-rays of about 1 nm, radiation light of about 26 nm or about 39 nm in wavelength, for example, light in the ultraviolet region such as g-line and i-line, far ultraviolet (DUV) light such as KrF excimer laser, ArF excimer laser, Vacuum ultraviolet (VUV) light such as an F ₂ laser, an Ar ₂ laser, a Kr ₂ laser, or the like can be used. In the first and second embodiments, an SOR or a laser plasma X which supplies radiation light (soft X-ray) having a wavelength of about 13 nm as a light source is used.
When a radiation source is applied, a reflective mask is used as a mask, and all optical members constituting the illumination optical system are reflective members.

In the third embodiment, since a refracting member is provided,
For example, light in the ultraviolet region such as g-line and i-line, deep ultraviolet (DUV) light such as KrF excimer laser, ArF excimer laser,
Vacuum ultraviolet (VUV) light such as an F ₂ laser, a Kr ₂ laser, an Ar ₂ laser, or the like can be used. As the light source, for example, wavelengths 248 nm, 193 nm, 157 nm, 146 n
m, YA having an oscillation spectrum at any of 126 nm
A harmonic of a solid-state laser such as a G laser may be used.

When radiation having a wavelength of 100 nm or less is used, the optical path from the mask (first surface) to the wafer (second surface) is in a vacuum atmosphere. In the case of using radiation in a vacuum ultraviolet region, particularly a wavelength of 160 nm or less, the optical path from the mask (first surface) to the wafer (second surface) is replaced with a helium gas atmosphere.

The magnification of the projection optical system is not limited to a reduction system, but may be an equal magnification system or an enlargement system.

Further, the present invention relates to an exposure apparatus for transferring a device pattern onto a glass plate, which is used not only for an exposure apparatus used for manufacturing a semiconductor element but also for a display including a liquid crystal display element and the like, and a thin film magnetic head. The present invention can also be applied to an exposure apparatus used for manufacturing a device, for exposing a device pattern onto a ceramic wafer, an exposure apparatus used for manufacturing an imaging device (such as a CCD), and the like. Further, the present invention can be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate, a silicon wafer, or the like in order to manufacture a reticle or a mask.

[0077]

As described above, according to the projection optical system of the present invention, the wavelength of 200 nm or less, especially 100 nm or less.
It has a large numerical aperture in the soft X-ray wavelength range of
It is possible to provide a projection optical system having a resolution significantly smaller than nm. Further, since the projection exposure apparatus according to the present invention includes the above-described projection optical system, a device having a fine pattern can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a lens configuration of a projection optical system according to a first example.

FIGS. 2A and 2B are diagrams illustrating a shielding area of the projection optical system according to the first embodiment.

FIG. 3 is a diagram illustrating lateral aberration of the projection optical system according to the first example.

FIG. 4 is a diagram showing a lens configuration of a projection optical system according to Example 2.

FIG. 5 is a diagram illustrating lateral aberration of a projection optical system according to Example 2.

FIG. 6 is a diagram illustrating a lens configuration of a projection optical system according to a third example.

FIG. 7 is a diagram illustrating lateral aberration of a projection optical system according to Example 3.

FIG. 8 is a diagram illustrating a configuration of a projection exposure apparatus including a projection optical system according to an embodiment of the present invention.

[Explanation of symbols]

 M Mask M1 to M6 Reflecting mirror L1 Lens component MS Primary mirror MF Secondary mirror W Wafer EA Field of view SA Exposure area S1, S2 Stop AP1, AP2 Opening K1 First imaging optical system K2 Second imaging optical system I1, I1 '' Intermediate image I2 Final image AX Optical axis TL Projection optical system 1 Light source 5 Reticle stage 11 Wafer stage

Claims (11)

[Claims] 1. A projection optical system for projecting an image on a first surface onto a second surface, wherein the projection optical system has an arc-shaped field-of-view region in a region not including the optical axis and a shielding region on a pupil plane. Projection optical system. 2. The projection optical system according to claim 1, further comprising: a first imaging optical system for forming an intermediate image of the first surface; and a final image of the first surface based on light emitted from the intermediate image. A second imaging optical system formed on a second surface, the first imaging optical system has at least two reflecting surfaces, and the second imaging optical system has a light passing portion The projection optical system according to claim 1, wherein the projection optical system has at least one reflecting surface. 3. The projection optical system according to claim 1, wherein the shielding area has a ring shape. 4. A projection optical system for projecting an image on a first surface onto a second surface, comprising: a first imaging optical system for forming an intermediate image on the first surface; and a radiant light from the intermediate image. A second imaging optical system for forming a final image of the first surface on the second surface based on the first image, wherein the first imaging optical system has at least two reflecting surfaces, The imaging optical system has at least one reflection surface having a light passing portion. 5. The projection optical system includes: a first imaging optical system for forming an intermediate image of the first surface; and a final image of the first surface based on light emitted from the intermediate image. A second imaging optical system formed on a second surface, wherein the first imaging optical system has at least one positive power reflecting surface and at least one negative power reflecting surface, The second imaging optical system includes a primary mirror provided in the vicinity of the intermediate image, and a secondary mirror provided on the second surface side with respect to the primary mirror. A sub-mirror having a second light-passing portion and a second reflection surface, and the radiated light from the intermediate image is provided by the primary mirror. Radiation light reflected by the second reflection surface of the secondary mirror via the first light passage portion and reflected by the second reflection surface of the secondary mirror is reflected by the first reflection surface of the primary mirror The radiation image reflected by the first reflecting surface of the primary mirror forms the final image on the second surface via the second light passing portion of the secondary mirror. The projection optical system according to any one of claims 1 to 4. 6. The projection optical system according to claim 1, wherein all of the optical elements constituting the projection optical system are reflection surfaces. 7. The projection optical system includes: a first imaging optical system for forming an intermediate image of the first surface; and a final image of the first surface based on light emitted from the intermediate image. A second imaging optical system formed on a second surface, the first imaging optical system has at least one refractive lens component, and the projection optical system has the first surface side and the The projection optical system according to claim 1, wherein the projection optical system is a telecentric optical system on the second surface side. 8. The projection optical system according to claim 1, wherein the optical axes of all the optical elements constituting the projection optical system are located on the same straight line. 9. The projection optical system includes: a first imaging optical system for forming an intermediate image of the first surface; and a final image of the first surface based on light emitted from the intermediate image. A second imaging optical system formed on a second surface, and a telecentric optical system on the second surface side, wherein the shielding region is provided near a pupil plane in the first imaging optical system. The projection optical system according to any one of claims 1 to 3, or 5 to 8, wherein a shielding member for forming (1) is disposed. 10. The projection optical system, comprising: a first imaging optical system for forming an intermediate image of the first surface; and a final image of the first surface based on light emitted from the intermediate image. A second imaging optical system formed on a second surface, wherein the first imaging optical system has a reflecting mirror arranged near a pupil plane, and the reflecting surface of the reflecting mirror has a predetermined shape. The projection optical system according to any one of claims 1 to 9, comprising: a reflection region having a reflectance; and a low reflectance region having a reflectance lower than the reflectance of the reflection region. . 11. A projection exposure apparatus for projecting and transferring an image of a mask on which a predetermined pattern has been formed onto a photosensitive substrate, and a radiation source for supplying radiation of a predetermined wavelength. A projection optical system, a first stage for positioning the mask on the first surface, and a second stage for positioning the photosensitive substrate on the second surface. .