JPH08139012A - Manufacture of circuit, and aligner - Google Patents

Abstract

PURPOSE: To enable printing a fine circuit pattern, by reducing imaging magnification, correcting the coma generated at the time of reduction, forming a circuit pattern image on an intermediate image surface with an imaging optical system constituted of reflecting mirrors, and again forming the image on an object to be exposed. CONSTITUTION: A meniscus lens L11 is so arranged that only the luminous flux reflected by a concave mirror M13 transmits. Thereby off-axis aberration and coma which are mostly generated when a demagnification system is constituted are corrected. A second imaging system is so constituted that the luminous flux from an object point P2 passes two meniscus lenses L21 , L22 , a concave mirror M21 , and two meniscus-shaped lens L22 ', L21 ', and then forms an image at a second image point P2 '. Thereby the residual aberration and the chromatic aberration in the first imagery system can be excellently corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a circuit such as IC and LSI, and an exposure apparatus used when manufacturing a circuit such as IC and LSI.

[0002]

2. Description of the Related Art Conventionally, IC, L
A reflective off-axis imaging optical system for printing a pattern of an integrated circuit such as SI on a silicon wafer is disclosed in, for example, JP-A-48-1.
2039, "Unit Magnification Reflective Optical System," JP-A-52-5544
It is proposed in JP-A No. 53-100230, "Ring-field optical system", and JP-A No. 58-219517, "Inclined-angle off-axis optical device".

In Japanese Patent Laid-Open No. 48-12039 and Japanese Patent Laid-Open No. 52-5544, two reflecting mirrors, a concave mirror and a convex mirror, are arranged so that their centers of curvature are concentric or non-concentric, and the entire system is imaged. The image forming optical system is configured so that the magnification is the same.

In Japanese Patent Laid-Open No. 53-100230, in addition to a concave mirror and a convex mirror, a meniscus lens having a negative refractive power is used to improve optical performance. Further, Japanese Patent Application Laid-Open No. 58-219517 proposes a catadioptric optical system having a uniform imaging magnification with improved optical performance by combining a reflecting system and a refracting system.

An image-forming optical system of this kind, which is composed of a reflecting mirror having an image-magnification magnification of 1 ×, has a circuit pattern in that coma and distortion, which are chromatic aberrations and asymmetrical aberrations, hardly occur. Although it is excellent as an image forming optical system for printing, it is difficult to print a finer circuit pattern because the image forming magnification is equal.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a circuit and an exposure apparatus using an imaging optical system composed of a reflecting mirror, which enables printing of a finer circuit pattern. is there.

[0007]

A method of manufacturing a circuit according to the present invention is a method of manufacturing a circuit, which includes a step of forming an image of a circuit pattern on an object to be exposed by an image forming optical system including a reflecting mirror. The imaging optical system is made to have a reduced imaging magnification, and the coma aberration generated when the imaging magnification is reduced is corrected. It is characterized in that it is re-imaged on the object to be exposed after the formation.

The exposure apparatus of the present invention is an exposure apparatus for projecting a pattern of a mask onto an object to be exposed by a projection optical system, wherein the projection optical system has a reduction magnification and an imaging optical system composed of a reflecting mirror. And an image forming optical system including the reflecting mirror, the image forming optical system including the reflecting mirror having an intermediate image plane, and forming an image of the circuit pattern on the intermediate image plane. It is characterized in that it is re-imaged on the object to be exposed after the formation.

[0009]

1 is a schematic view of an optical system of an embodiment of an exposure apparatus for the step of forming an image of a circuit pattern on an object to be exposed by an image forming optical system comprising a reflecting mirror of the present invention. FIG. 2 is an aberration diagram of a numerical example of the present invention. In the aberration diagrams, (A) is a sagittal image plane, and (B) is a meridional image plane. The catadioptric optical system of FIG. 1 has a meniscus shape and three reflecting mirrors, a concave mirror M ₁₁ , a convex mirror M _12, and a concave mirror M ₁₃ , which have a center of curvature in the same direction in order from the object side and are located on the same optical axis. The first image forming system is configured by the lens L ₁₁ of
Two meniscus lenses L ₂₁ , L ₂₂ , a concave mirror M ₂₁
The two meniscus lenses L ₂₂ ′ and L ₂₁ ′ form a second image forming system.

Then, in the figure, a light beam from an off-axis object point P in a predetermined region above the optical axis is reflected in the order of reflecting mirrors M ₁₁ , M ₁₂ , and M ₁₃ , passes through a lens L _11, and then the first An image is formed at the image point P ₁ ′. The first image point P ₁ 'is object point P ₂ next to the second imaging system, the light beam from the object point P ₂ 2 two lenses L _21, L _22,
An image is formed on the second image point P ₂ ′ via the concave mirror M ₂₁ and the two lenses L ₂₂ ′ and L ₂₁ ′.

In this embodiment, the first imaging system uses a concave mirror M ₁₁ , a convex mirror M _12, and a concave mirror M ₁₃ for reflecting a light beam from the object point P ₁ , three reflecting mirrors having so-called positive, negative, and positive refractive powers and a meniscus. The image is formed on the first image point P ₁ ′ after passing through the shaped lens L _11, and aberrations generated by the respective reflecting mirrors are corrected in a well-balanced manner.

In particular, by disposing the meniscus lens L ₁₁ so that only the light beam reflected by the concave mirror M ₁₃ is transmitted, off-axis aberrations and coma aberrations (asymmetrical aberrations) that often occur when a reduction system is constructed. Is corrected well.

The lens L ₁₁ cancels chromatic aberrations caused by the refracting system arranged in the second image forming system, thereby facilitating the aberration correction of the second image forming system.

First, the light flux from the object point P ₂ passes through the second imaging system to be 2
It passes through two meniscus-shaped lenses L ₂₁ and L ₂₂ , a concave mirror M ₂₁ and two meniscus-shaped lenses L ₂₂ ′ and L ₂₂ .
After passing through ₂₁ ′, the image is formed at the second image point P ₂ ′, and the residual aberration and the chromatic aberration in the first image forming system are well corrected.

In particular, the glass material of each lens has a short wavelength (wavelength 2
(30 to 400 nm) side, although it is composed only of quartz glass having good transmittance, by specifying the lens shape as described above, good chromatic aberration correction is achieved as shown in the aberration charts described later. In particular, the light flux from the object point P _{2 is} passed through the two lenses L ₂₁ and L ₂₂ and also the two lenses L ₂₂ ′ and L ₂₁ ′ so that the aperture ratio is increased and the coma aberration, the off-axis halo, etc. are overall. In addition to reducing the amount of aberration, the chromatic aberration is corrected well together with the lens L ₁₁ of the first imaging system. And even though the reflection system is adopted, the vignetting of the light flux is minimized.

In this embodiment, the image forming magnification of the first image forming system is set to 0.
11 times, the imaging magnification of the second imaging system is 2.26 times, and constitutes a 0.25 times reduction catadioptric optical system as a whole.

As described above, by constructing one of the image forming systems as the magnifying system and the other image forming system as the reducing system so that the entire system becomes the reducing system, the off-axis spherical surface generated in each of the image forming systems is formed. Various aberrations such as aberration, coma, and distortion are favorably corrected, and a catadioptric optical system having a large aperture ratio is easily achieved despite a simple configuration.

Incidentally, in this embodiment, in order to further favorably correct off-axis spherical aberration, coma aberration and chromatic aberration and achieve a reduction system with higher resolution, the lens L ₁₁ is a meniscus whose concave surface faces the concave mirror M ₁₃ side. Shaped lens again lens L ₂₁ , L
_It is preferable that each of ₂₂ , L ₂₁ ′ and L ₂₂ ′ is formed of a meniscus lens having a convex surface facing the concave mirror M ₂₁ side.
Further, it is preferable that the lens L ₁₁ and the lens L ₂₁ and the lens L ₂₁ ′ are constituted by lenses having a positive refractive power, and the lens L ₂₂ and the lens L ₂₂ ′ are constituted by lenses having a negative refractive power, in order to achieve good aberration correction.

In this embodiment, the lens L ₂₁ and the lens L ₂₁ ′ are the same lens, and the lens L ₂₂ and the lens L ₂₂ ′ are the same lens. However, each lens is a separate lens. In this case, the degree of freedom is increased, and aberration correction can be achieved better. Further, the object of the present invention can be achieved even if the lens L ₁₁ is composed of two or more meniscus lenses.

In this embodiment, the chief ray from the object point P ₁ intersects the optical axis between the convex mirror M ₁₂ and the concave mirror M ₁₃ and between the concave mirror M ₂₁ and the lens L ₂₂ ′. , The entire optical system is made compact, and the high-performance catadioptric optical system is achieved while reducing the vignetting of the light flux.

In this embodiment, each lens is made of the same glass material as described later, but CaF ₂ or the like, which has good transmittance on the short wavelength side, may be used.

Next, numerical examples of the embodiment shown in FIG. 1 will be shown. Ri represents a radius of curvature of the i-th reflector and lens surface counted in order of progress of the light from the object point P _1, Di is the i-th and the (i + 1) th lens thickness counting the order of progress of the light from the object point P ₁ And air space, SiO ₂ is quartz glass. The air gap and the refractive index are shown as positive when measured from the left to the right in the light traveling direction and as negative when measured in the opposite direction.

[0023] NA = 0.25, slit width 1.5mm, magnification 1/4

[0024]

[Table 1]

[0025]

According to the present invention, a pattern such as a circuit pattern can be formed into a reduced image by an image forming optical system including a reflecting mirror, and a coma aberration generated in the image forming optical system can be corrected to form a clear image. Therefore, it becomes possible to accurately print a finer pattern on the object to be exposed, which is also useful for supplying ICs, LSIs and the like having a high degree of integration.

[Brief description of drawings]

FIG. 1 is an optical sectional view of a numerical example of the present invention.

FIG. 2 is an aberration diagram of numerical examples of the present invention.

[Explanation of symbols]

Y ₀ Object height P ₁ First object point P ₂ Second object point P ₁ ′ First image point P ₂ ′ Second image point L ₁₁ , L ₂₁ , L ₂₂ , L ₂₁ ′, L ₂₂ ′ Correcting means

Claims (6)

[Claims] 1. A method of manufacturing a circuit including a step of forming an image of a circuit pattern on an object to be exposed by an image forming optical system including a reflecting mirror, wherein an image forming magnification of the image forming optical system including the reflecting mirror is reduced. By correcting the coma aberration that occurs when the image forming magnification is reduced, and by the image forming optical system including the reflecting mirror,
A method of manufacturing a circuit, comprising forming an image of the circuit pattern on an intermediate image plane and then re-imaging the image on the exposed body. 2. An exposure apparatus for projecting a mask pattern onto an object to be exposed by a projection optical system, wherein the projection optical system has a reduction magnification and is composed of a reflecting mirror, and the reflecting mirror. And an image forming optical system including the reflecting mirror, the image forming optical system having an intermediate image plane, and forming an image of the circuit pattern on the intermediate image plane. An exposure apparatus which re-images on the object to be exposed. 3. The exposure apparatus according to claim 2, wherein the correction means includes a refracting optical system. 4. An image forming optical system comprising the reflecting mirror is
A second two image forming systems are arranged in order, and the first and second image forming systems are arranged so that the image of the object formed by the first image forming system is re-imaged by the second image forming system. The exposure apparatus according to claim 2, wherein the exposure apparatus is configured. 5. The first light source is arranged in the order of traveling from the object side.
The imaging system has a concave mirror M ₁₁ , a convex mirror M ₁₂ , and a concave mirror M ₁₃ ,
The exposure apparatus according to claim 4, wherein the second imaging system has a concave mirror M ₂₁ . 6. The correction means includes a meniscus-shaped lens L ₁₁ , two meniscus-shaped lenses L ₂₁ , L ₂₂ , and two meniscus-shaped lenses L ₂₂ ′, L _{21 in the} order in which light travels from the object side. ???
The exposure apparatus described.