TW201921024A - Catadioptric optical system, illumination optical system, exposure apparatus and article manufacturing method - Google Patents

Abstract

The present invention relates to a catadioptric optical system, an illumination optical system, and an exposure device. The catadioptric optical system, which is object plane telescentric or image plane telecentric, comprises a first reflection surface, a second reflection surface, a third reflection surface, and a fourth reflection; and a refraction surface having a positive refractive power. The refraction surface is arranged between the object plane and the first reflection surface. Light exiting from the object plane passes through, in sequence, the refraction surface, the first reflection surface, the refraction surface, the second reflection surface, the refraction surface, the third reflection surface, and the fourth reflection surface to reach the image plane.

Description

Reflective refractive optical system, illumination optical system, exposure apparatus, and article manufacturing method

The present invention relates to a catadioptric optical system, an illumination optical system, an exposure apparatus, and an article manufacturing method.

The exposure apparatus is a device that transfers a pattern of a master to a photosensitive substrate (a substrate on which a photoresist layer is formed) via a projection optical system in a photolithography program for manufacturing an article such as a semiconductor device or a display device. For example, an exposure apparatus for manufacturing a display device requires performance in which a pattern can be transferred to a larger-area substrate with high resolution. In order to cope with such a request, it is useful to obtain a scanning exposure apparatus which is high in resolution and can be exposed to a large screen. The scanning exposure apparatus exposes the substrate with light that is formed into an arc shape while scanning the original plate and the substrate. At this time, the original plate is illuminated with light that is formed into an arc shape, and the original pattern is projected onto the substrate by the light that is formed into an arc shape.

Patent Document 1 describes an illumination optical system that illuminates an original plate with light that is formed into an arc shape. However, in order to illuminate an object with uniform energy in accordance with a desired shape, it is necessary to image an opening portion of a field diaphragm provided to the illumination optical system to an imaging optical system of the object. In general, such an imaging optical system is referred to as a shadow imaging system. In the case of illuminating a large picture, in order to minimize the size of the optical elements around the field stop, the shadow imaging system is preferably constructed of a mirror system with magnification.

Patent Document 2 describes an imaging optical system that satisfactorily suppresses aberrations. The imaging optical system described in Patent Document 2 is called an OFNER optical system, and the three curvature mirrors are used to bend the light to form an image. The Offner optical system is an equal magnification system for one-time imaging, but as described in Patent Document 3, the magnification can be made according to the positions of the three curvature mirrors. Further, as described in Patent Document 4, there is an optical system that corrects aberrations by using multiple imaging.
[Previous Technical Literature]
[Patent Literature]

Japanese Unexamined Patent Publication No. Hei No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei.

However, in the imaging optical system described in Patent Documents 2 and 3, since the back focal length of the optical system is long, for example, when mounted on an exposure apparatus, the exposure apparatus is increased in size. Further, since the optical system described in Patent Document 4 is imaged a plurality of times, the overall length is long, and the size of the device is increased.

An object of the present invention is to provide a catadioptric optical system which is small and has a structure advantageous for the reduction of aberrations, and an apparatus including the same.

A first aspect of the present invention relates to a catadioptric optical system in which a object surface and an image surface are telecentric, the catadioptric optical system comprising: a first reflecting surface, a second reflecting surface, a third reflecting surface, and a fourth reflecting surface; a refractive surface of a positive refractive power, wherein the refractive surface is disposed between the object surface and the first reflecting surface, and the light from the object surface sequentially passes through the refractive surface, the first reflecting surface, the refractive surface, and The second reflecting surface, the refracting surface, the third reflecting surface, and the fourth reflecting surface reach the image surface.
A second aspect of the present invention relates to an illumination optical system comprising the catadioptric optical system according to the first aspect.
A third aspect of the present invention relates to an exposure apparatus comprising the catadioptric optical system according to the first aspect.
According to a fourth aspect of the present invention, in the article manufacturing method, the article manufacturing method includes the following steps of: exposing a substrate by using an exposure apparatus according to the third aspect; and developing the substrate; wherein the article is manufactured from the substrate.

According to the present invention, a catadioptric optical system which is small and has a structure advantageous for the reduction of aberrations and a device including the catadioptric optical system are provided.

Hereinafter, the present invention will be described by way of exemplary embodiments thereof with reference to the accompanying drawings.

The structure of the catadioptric optical system according to one embodiment of the present invention will be described with reference to Figs. 1, 2, and 3. The catadioptric optical system can be embedded, for example, in the illumination optical system 100 of the exposure apparatus. An example of the configuration of the illumination optical system 100 is shown in FIG. The illumination optical system 100 may include a light source unit 120, a wavelength filter 104, a first optical system 105, a deflection mirror 107, a second optical system 140, a fly's eye optical system 109, an aperture stop 110, a third optical system 150, and a field of view. The aperture 111 and the fourth optical system 160. The illumination optical system 100 is configured to illuminate the original M on the illuminated surface. The light source section 120 may include a light source 101 and an elliptical mirror 102.

The light source 101 can be, for example, a high pressure mercury lamp, a xenon lamp or a quasi-molecular laser. The elliptical mirror 102 is a collecting optical system for collecting light emitted from the light source 101, and forms a shape in which a part of an elliptical shape is used. The light source 101 can be disposed in one of the two focal points of the elliptical mirror 102 (first focus).

The light emitted from the light source 101 and reflected by the elliptical mirror 102 is condensed to the wavelength filter 104 disposed in the vicinity of the other focus (second focus) of the elliptical mirror 102. The wavelength filter 104 changes the spectral distribution of the light. The light passing through the wavelength filter 104 is guided to the deflecting mirror 107 by the first optical system 105, and is reflected by the deflecting mirror 107. In the example shown in FIG. 1, two light source units 120 are provided, but the light source unit 120 may be one or three or more.

The first optical system 105 is configured such that the surface 108 is substantially at the position of Fourier transform with respect to the light from the second focus of the elliptical mirror 102. Light from the Fourier transform plane 108 is directed by the second optical system 140 to the fly's eye optical system 109. The second optical system 140 is configured such that the incident surface of the fly's eye optical system 109 substantially becomes a Fourier switching position with respect to the surface 108.

In Fig. 2, a fly's eye optical system 109 is shown. As shown in FIG. 2, the fly's eye optical system 109 can include two lens groups 131, 132. Each lens group can be configured by arranging a plurality of plano-convex lenses on a plane. A plano-convex lens constituting the lens group 132 is disposed at a focus position of the plano-convex lens constituting the lens group 131. Further, the convex surface of the plano-convex lens constituting the lens group 131 and the convex surface of the plano-convex lens constituting the lens group 132 are arranged to face each other. A secondary light source distribution (effective light source distribution) is formed on the exit surface side of such a fly's eye optical system 109.

The light beam emitted from the exit surface of the fly's eye optical system 109 is guided to the field stop 111 by the third optical system 150 via the aperture stop 110. The aperture stop 110 determines the incident angle distribution shape (effective light source) of the illuminated surface according to the shape of the opening. The third optical system 150 is configured such that the position of the field stop 111 substantially becomes a Fourier transform plane with respect to the aperture stop 110. Since the secondary light source distribution is formed on the exit surface side of the fly's eye optical system 109, it has a uniform light intensity distribution on the field stop 111.

FIG. 3 illustrates the shape of the field stop 111. The field stop 111 blocks light other than the arc-shaped transmissive portion 23. The light that has been formed into an arc shape by the field stop 111 uniformly illuminates the original M via the fourth optical system 160. The shape of the opening of the field diaphragm 111 is not limited to an arc shape, and may be other shapes. The opening of the field stop 111 may have, for example, a rectangular shape that is inscribed in an arc shape. The fourth optical system 160 is a catadioptric optical system. Hereinafter, the fourth optical system 160 will be described as the catadioptric optical system 160.

Hereinafter, a catadioptric optical system 160 according to an exemplary embodiment of the present invention will be described with reference to FIGS. 4A, 5A, 6A, 7A, 8A, and 9A. The catadioptric optical system 160 is telecentric on the object plane OBJ and the image plane IMG. The catadioptric optical system 160 may include a first mirror (first reflecting surface) M1, a second mirror (second reflecting surface) M2, a third mirror (third reflecting surface) M3, and a fourth mirror (fourth) Reflective surface) M4. In addition, the catadioptric optical system 160 may include a refractive surface having a positive refractive power disposed between the object plane OBJ and the first mirror M1. This refractive surface can be constituted by the lens L1. The light from the object plane OBJ sequentially reaches the image plane IMG via the refracting surface, the first mirror M1, the refracting surface, the second mirror M2, the refracting surface, the third mirror M3, and the fourth mirror M4. .

The refractive surface may be composed of one lens L1 or at least two lenses. In the latter, the respective faces of at least two lenses may constitute mutually different regions in the refractive surface. The lens L1 may have two refractive faces. The refractive surface may have an aspherical shape. The refractive surface may be configured to satisfy the | P(sum)|<|P(L1)|.

At least one of the first mirror M1, the second mirror M2, the third mirror M3, and the fourth mirror M4 may have an aspherical shape.

The catadioptric optical system 160 can be configured to have no imaging plane between the object plane OBJ and the image plane IMG. In other words, the catadioptric optical system 160 may be an optical system of one-time imaging having an imaging plane only on the image plane IMG.

The catadioptric optical system 160 can be configured to satisfy S1/TT when the total length of the catadioptric optical system 160 is TT and the distance between the object surface OBJ and the refractive power surface closest to the object plane OBJ is S1. 0.1. The catadioptric optical system 160 can be configured such that the distance from the object plane OBJ to the refractive power surface closest to the object plane OBJ is S1, and the distance from the final refractive power surface to the image plane IMG is set to Sk. When Sk/S1<3.0 is satisfied.

The catadioptric optical system 160 can be configured such that the traveling direction of the light emitted from the object plane OBJ is the same as the traveling direction of the light incident on the image plane IMG. The catadioptric optical system 160 can be configured such that the pupil position of the catadioptric optical system 160 is located between the first mirror M1 and the second mirror M2. The catadioptric optical system 160 may include an aspherical lens for correcting telecentricity in at least one of the vicinity of the object plane OBJ and the vicinity of the image plane IMG.

Hereinafter, a design example of the catadioptric optical system 160 will be described.

(Design example 1)
Table 1A shows the optical specifications of Design Example 1.

The wavelength of light is 365 nm to 435 nm, and NAil is the numerical aperture at the image plane IMG of the catadioptric optical system 160, which is 0.09 in Design Example 1. The exposure width, the slit width, and the circular arc R are parameters defining the shape of the illumination light at the image plane IMG of the fourth optical system 160, which is shown in FIG. 4D. The magnification is the imaging magnification of the catadioptric optical system 160.

Table 1B shows the structure of the catadioptric optical system 160 of Design Example 1.

r (mm) is the radius of curvature of the face, d (mm) is the face spacing, and n is the glass. Here, the refractive index of air is set to 1, and the surface which becomes -1 represents a reflection surface. SiO ₂ represents synthetic quartz. In addition, the center of curvature of each face is located on the optical axis.

4A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 1. Here, the object plane OBJ of the catadioptric optical system 160 has a circular arc shape, and FIG. 4A shows light coming out from the center of the arc shape and light coming out from the end. Fig. 4A shows a section through the center of a circular arc shape. Therefore, in Fig. 4A, it seems that the light from the end of the arc shape does not illuminate the reflecting surface, but the light is irradiated to the reflecting surface at the section shifted from Fig. 4A. This point is common to FIGS. 5A, 6A, 7A, 8A, and 9A.

In Fig. 4A, OBJ represents an object plane, and IMG represents an image plane. L1 is a lens having a positive refractive power and has two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) having positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) having negative refractive power.

The light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L1 (face number 4, 5), M2 (face number 6), and L1 in order from OBJ. (surface numbers 7, 8), M3 (face number 9), and M4 (face number 10) are imaged on the IMG. The pupil of the catadioptric optical system 160 may also be located between M1 and L1 with an aperture stop at the pupil position.

FIG. 4B shows an expanded view of the catadioptric optical system 160 of Design Example 1. The full length TT and S1, Sk of the catadioptric optical system 160 are defined as shown in FIG. 4B. The expanded view is a reference map for making the overall refractive power configuration of the catadioptric optical system 160 easy to understand, and the actual catadioptric optical system 160 has a mirror. In Fig. 4B, the mirror is represented by a thin lens equivalent thereto. This is common to all of FIGS. 5B, 6B, 7B, 8B, and 9B.

4C shows the 3rd Petzval term of L1, M1, M2, M3, M4 and the overall 3rd Petzval sum (SUM) of the catadioptric optical system 160. Here, the Perzian term is a value obtained by dividing the refractive power of the lens L1 and the mirrors M1, M2, M3, and M4 by the refractive index. The Petzval sum (SUM) is the sum of the 3rd Petzval terms of L1, M1, M2, M3, and M4.

Table 1C shows the full lengths TT, S1, Sk of the catadioptric optical system 160 of Design Example 1.

The total length TT of the catadioptric optical system 160 is a simple summation of the intervals of the plurality of faces from the object plane OBJ of the catadioptric optical system 160 to the image plane IMG. That is, the full length TT is a value obtained by integrating the absolute values of d in Table 1B. S1 is a distance from the object surface OBJ to the first refractive power surface (the refractive power surface closest to the object surface OBJ, that is, the surface having the surface number 1), and Sk is the final refractive power surface (closest to the image surface IMG) The distance from the refractive power surface, that is, the surface numbered from 10 to the image surface IMG.

S1/TT is a ratio of S1 to TT. If the value is large, for example, a plurality of field diaphragms can be disposed in the vicinity of the object plane OBJ, and the degree of freedom in design increases. Sk/S1 is the ratio of Sk to S1. In the case where the catadioptric optical system 160 is an amplification system, it can be said that the smaller the value, the more compact the optical system.

Table 1D shows the optical properties of the catadioptric optical system 160 of Design Example 1.

P(sum) represents the Petzval sum (SUM) of the catadioptric optical system 160, and P(L1) represents the Petzval term of L1. Further, the light spot RMS indicates the worst value of the RMS spot diameter in the effective region, dist indicates the distortion, and the range indicates the deviation of the telecentricity in the slit width direction.

As in the case of the design example 1, the light beam from the object plane OBJ passes through the lens L1 three times. If the region where the light beam passes through the lens L1 for the first time does not overlap with the region where the light beam passes through the lens L1 for the second time, it is not necessary to use the same lens L1. However, when the NA of the image plane IMG is large and the magnification is small, etc., it is difficult to separate the regions through which the light beam transmits, and it is necessary to use the same lens L1.

(Design example 2)
Table 2A shows the optical specifications of Design Example 2.

The wavelength of light is 365 nm to 435 nm, and the NAil is 0.09. Table 2B1 and Table 2B2 show the structure of the catadioptric optical system 160 of Design Example 2.

The ASP of the surface number 1 indicates an aspherical surface, and the numerical value described in Table 2B2 is used as a function of h as expressed by the formula (1). In the formula (1), h is a distance from the optical axis, and Z is a position in the optical axis direction.

FIG. 5A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 2. OBJ represents the object surface and IMG represents the image surface. L2 is an aspherical lens having a negative refractive power. L1 is a lens having a positive refractive power and has two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) having positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) having negative refractive power.

The light beam from the object plane OBJ at a predetermined NA passes through L2 (face number 1, 2), L1 (face number 3, 4), M1 (face number 5), and L1 (face number 6, 7) in order from OBJ. , M2 (face number 8), L1 (face number 9, 10), M3 (face number 11), M4 (face number 12). This beam is then imaged at the IMG. The pupil of the catadioptric optical system 160 may also be located between M1 and L1 with an aperture stop at the pupil position.

FIG. 5B shows an expanded view of the catadioptric optical system 160 of Design Example 2. 5C shows the 3rd Petzval term of L1, L2, M1, M2, M3, M4 and the overall 3rd Petzval sum (SUM) of the catadioptric optical system 160.

Table 2C shows the total lengths TT, S1, Sk, S1/TT, and Sk/S1 of the catadioptric optical system 160 of Design Example 2.

Table 2D shows the optical properties of the catadioptric optical system 160 of Design Example 2.

The catadioptric optical system 160 of the design example 2 has a smaller value of the range of the distance than the catadioptric optical system 160 of the design example 1. This is because the range of the telecentricity is corrected by the aspherical lens L2 having a negative refractive power.

In Design Example 2, the aspherical lens L2 is disposed in the vicinity of the object plane OBJ, but the aspherical lens L2 may be disposed in the vicinity of the image plane IMG. In other words, the aspherical lens can be disposed in at least one of the vicinity of the object plane OBJ and the vicinity of the image plane IMG. However, in the case of the amplification system, the effective diameter of the optical element in the vicinity of the image plane IMG becomes large, so it is preferably disposed in the vicinity of the object plane OBJ if possible.

(Design example 3)
Table 3A shows the optical specifications of Design Example 3.

The wavelength of light is 335 nm to 405 nm, and the NAil is 0.126. Table 3B1 and Table 3B2 show the structure of the catadioptric optical system 160 of Design Example 3.

The ASP of the face numbers 2, 4, and 8 represents an aspherical surface whose shape is defined by the above formula (1). FIG. 6A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 3. OBJ represents the object surface and IMG represents the image surface. L1 is a lens having a positive refractive power and has two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) having positive refractive power, M2 is a mirror (reflecting surface) having negative refractive power, and M3 is a plane mirror.

The light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L1 (face number 4, 5), M2 (face number 6), and L1 in order from OBJ. (surface numbers 7, 8), M3 (face number 9), and M4 (face number 10) are imaged on the IMG. The pupil of the catadioptric optical system 160 may also be located adjacent to M2 with an aperture stop at the pupil position.

FIG. 6B shows a developed view of the catadioptric optical system 160 of Design Example 3. 6C shows the 3rd Petzval term of L1, M1, M2, M3, M4 and the 3rd Petzval sum (SUM) of the catadioptric optical system 160 as a whole.

Table 3C shows the total lengths TT, S1, Sk, S1/TT, and Sk/S1 of the catadioptric optical system 160 of Design Example 3.

Table 3D shows the optical properties of the catadioptric optical system 160 of Design Example 3.

The catadioptric optical system 160 of the design example 3 has a larger value of S1/TT than the catadioptric optical system 160 of the design examples 1 and 2. The aberration and the telecentricity of the optical system are well corrected by the aspherical lens L2, whereby the refractive force arrangement such that S1 is made larger can be performed.

(Design example 4)
Table 4A shows the optical specifications of Design Example 4.

The wavelength of light is 365 nm to 435 nm, and the NAil is 0.09. Table 4B1 and Table 4B2 show the structure of the catadioptric optical system 160 of Design Example 4.

The ASP of the surface numbers 2, 4, 8, and 9 represents an aspherical surface whose shape is defined by the above formula (1). FIG. 7A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 4. OBJ represents the object surface and IMG represents the image surface. L1 is a lens having a positive refractive power and has two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1, M3, and M4 are mirrors (reflecting surfaces) having positive refractive power, and M2 is a mirror (reflecting surface) having negative refractive power.

The light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L1 (face number 4, 5), M2 (face number 6), and L1 in order from OBJ. (face numbers 7, 8), M3 (face number 9), M4 (face number 10). The beam is then imaged at the IMG. The pupil of the catadioptric optical system 160 may also be located near L1 with an aperture stop at the pupil position.

FIG. 7B shows an expanded view of the catadioptric optical system 160 of Design Example 4. Fig. 7C shows the 3rd Petzval term of L1, M1, M2, M3, M4, and the 3rd Petzval sum (SUM) of the catadioptric optical system 160 as a whole. Table 4C shows the total lengths TT, S1, Sk, S1/TT, Sk/S1 of the catadioptric optical system 160 of Design Example 4.

Table 4D shows the optical properties of the catadioptric optical system 160 of Design Example 4.

The catadioptric optical system 160 of the design example 4 has a shorter overall length TT than the catadioptric optical system 160 of the design example 1. The aberration and the telecentricity of the catadioptric optical system 160 are well corrected by the aspherical lens L1 and the aspherical mirror M3, whereby a compact refractive force configuration can be realized as a whole.

(Design example 5)
Table 5A shows the optical specifications of Design Example 5.

The wavelength of light is 335 nm to 405 nm, and the NAil is 0.108. Table 5B1 and Table 5B2 show the structure of the catadioptric optical system 160 of Design Example 5.

The ASP of the surface numbers 2, 4, 8, and 9 represents an aspherical surface whose shape is defined by the above formula (1). FIG. 8A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 5. A cross-sectional view showing the optical system. OBJ represents the object surface and IMG represents the image surface. L1 is a lens having a positive refractive power and has two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) having positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) having negative refractive power.

The light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L1 (face number 4, 5), M2 (face number 6), and L1 in order from OBJ. (surface numbers 7, 8), M3 (face number 9), and M4 (face number 10) are imaged on the IMG. The pupil of the catadioptric optical system 160 may also be located near L1 with an aperture stop at the pupil position.

FIG. 8B shows an expanded view of the catadioptric optical system 160 of Design Example 5. FIG. 8C shows the 3rd Petzval term of L1, M1, M2, M3, M4 and the 3rd Petzval sum (SUM) of the catadioptric optical system 160 as a whole. FIG. 8B shows an expanded view of the catadioptric optical system 160 of Design Example 5. FIG. 8C shows the 3rd Petzval term of L1, M1, M2, M3, M4, and the 3rd Petzval sum (SUM) of the catadioptric optical system 160 as a whole.

Table 5C shows the total lengths TT, S1, Sk, S1/TT, Sk/S1 of the catadioptric optical system 160 of Design Example 5.

Table 5D shows the optical properties of the catadioptric optical system 160 of Design Example 5.

The catadioptric optical system 160 of the design example 5 has a smaller value of Sk/S1 than the catadioptric optical system 160 of the design example 4. This is because the value of NAil is larger than that of the design example 4, so that M4 is moved to the image plane IMG side in order to separate the light reflected by M3 from the light from M4 toward the image plane IMG.

(Design example 6)
Table 6A shows the optical specifications of Design Example 6.

The light wavelength was 335 nm to 405 nm, and the NAil was 0.126. Table 6B1 and Table 6B2 show the structure of the catadioptric optical system 160 of Design Example 6.

The ASP of the surface numbers 2, 4, 8, and 9 represents an aspherical surface whose shape is defined by the above formula (1). FIG. 9A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 6. OBJ represents the object surface and IMG represents the image surface. L1 is a lens having a positive refractive power and has two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) having positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) having negative refractive power.

The light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L1 (face number 4, 5), M2 (face number 6), and L1 in order from OBJ. (surface numbers 7, 8), M3 (face number 9), and M4 (face number 10) are imaged on the IMG. The pupil of the catadioptric optical system 160 may also be located near L1 with an aperture stop at the pupil position.

FIG. 9B shows an expanded view of the catadioptric optical system 160 of Design Example 6. FIG. 9C shows the 3rd Petzval term of L1, M1, M2, M3, M4 and the 3rd Petzval sum (SUM) of the catadioptric optical system 160 as a whole.

Table 6C shows the total lengths TT, S1, Sk, S1/TT, Sk/S1 of the catadioptric optical system 160 of Design Example 6.

Table 6D shows the optical properties of the catadioptric optical system 160 of Design Example 6.

The catadioptric optical system 160 of the design example 6 has a smaller value of Sk/S1 than the catadioptric optical system 160 of the design example 4. This is because the value of NAil is larger than in Design Example 4, so that M4 is placed closer to the image plane in order to separate the light reflected by M3 from the light from M4 toward the image plane IMG.

(exposure device)
FIG. 10 shows the configuration of an exposure apparatus 400 according to an embodiment of the present invention. The exposure device 400 includes an illumination optical system 100 that scans and exposes a substrate using slit light from the illumination optical system 100. The illumination optical system 100 includes a slit mechanism 181 that can adjust the shape of the opening.

The exposure apparatus 400 has a master stage 300 that holds the original plate, a substrate stage 302 that holds the substrate, and a projection optical system 301 that projects the original pattern onto the substrate. The projection optical system 301 is, for example, a projection optical system in which the first concave reflecting surface 71, the convex reflecting surface 72, and the second concave reflecting surface 73 are sequentially arranged in the optical path from the object surface to the image surface.

The exposure device 400 may further include a measurement unit 304 that measures the illuminance distribution of the light reaching the substrate stage 302 and measures the illuminance unevenness in the exposure region of the substrate. Further, the slit plate 303 is located between the substrate stage 302 and the measurement unit 304. The slit plate 303 is scan-driven in the exposure width direction of FIG. 4D by a driving portion (not shown) under the control of a control portion (not shown).

As shown in FIG. 10, the measuring portion 304 may include a sensor 305 and an optical system for guiding light that has passed through the slit plate 303 to the sensor 305. The operation of the measurement unit 304 is roughly as follows.

As shown in FIG. 11, the slit plate 303 is scanned in the X direction with respect to the region 401 of light imaged on the substrate stage 302. At this time, only the light formed on the opening portion 306 of the slit plate 303 among the light imaged in the region 401 is incident into the measurement portion 304. Light incident into the measuring portion 304 is guided to the sensor 305 via the optical system. The illuminance at each position in the area 401 is measured by reading the energy of the light reaching the sensor 305 while scanning the slit plate 303 in the X direction. From this, the illuminance unevenness can be calculated.

As described above, by adjusting the opening width of the slit mechanism 181 of the illumination optical system 100, illuminance unevenness can be reduced. For example, it is assumed that the measurement unit 304 measures the illuminance unevenness as shown in FIG. 12A. In this case, the width of the slit mechanism 181 at the portion where the illuminance is lowered is locally enlarged, and the width of the slit mechanism 181 at the portion where the illuminance is increased is locally narrowed, so that the illuminance distribution can be made uniform as shown in FIG. 12B.

The article manufacturing method according to one embodiment of the present invention may include an exposure program for exposing the substrate by the exposure device 400 and a developing program for developing the substrate. The substrate exposed in the exposure process has a photoresist on the surface, and in the exposure process, a latent image of the original pattern can be formed on the photoresist. In the developing process, the latent image can be developed to form a resist pattern. After the development process, for example, the substrate may be etched via the resist pattern or ions may be implanted into the substrate. The article that can be formed in this manner can include, for example, a display device (display panel), a semiconductor device (semiconductor wafer), and the like.

(Design Example 7)
Table 7A shows the optical specifications of Design Example 7.

The light wavelength is 335 nm to 405 nm, and the NAil is 0.09. Table 7B shows the structure of the catadioptric optical system 160 of Design Example 7.

FIG. 13A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 7. OBJ represents the object surface and IMG represents the image surface. L1 and L2 are respectively lenses having a positive refractive power and have two refractive faces. The total of the refractive powers of the two refractive surfaces has a positive refractive power. Thus, at least one of the refractive surfaces has a positive refractive power. M1 is the first mirror (first reflecting surface), M2 is the second mirror (second reflecting surface), M3 is the third mirror (third reflecting surface), and M4 is the fourth mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) having positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) having negative refractive power.

The light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L2 (face number 4, 5), M2 (face number 6), L2 in order from OBJ. (surface numbers 7, 8), M3 (face number 9), and M4 (face number 10) are imaged on the IMG. The pupil of the catadioptric optical system 160 may also be located near L2 with an aperture stop at the pupil position.

FIG. 13B shows an expanded view of the catadioptric optical system 160 of Design Example 6. FIG. 13C shows the 3rd Petzval term of L1, L2, M1, M2, M3, M4 and the 3rd Petzval sum (SUM) of the catadioptric optical system 160 as a whole.

In the design example 7, L1 and L2 are examples, and they are not limited to the current example as long as they are lenses having a positive refractive power.

Table 7C shows the total lengths TT, S1, Sk, S1/TT, Sk/S1 of the catadioptric optical system 160 of Design Example 7.

Table 7D shows the optical properties of the catadioptric optical system 160 of Design Example 7.

In the design example 7, L1 and L2 are examples, and they are not limited to the current example as long as they are lenses having a positive refractive power.

(anti-reflection film 1)
An anti-reflection film of the lens L1 constructed in the catadioptric optical system 160 of Design Example 4 will be described.

As shown in Fig. 7A, the light beam emerging from the object plane OBJ at a predetermined NA passes through L1 (face number 1, 2), M1 (face number 3), L1 (face number 4, 5), M2 (face) in order from OBJ. No. 6), L1 (face number 7, 8), M3 (face number 9), M4 (face number 10). The beam is then imaged at the IMG.

FIG. 14A is a view of the R1 surface (surface close to the OBJ side) of the lens L1 viewed from the OBJ side. A region 500 surrounded by a broken line in Fig. 14A is an effective region when the light beam from the OBJ is first incident on the R1 surface of L1, and corresponds to the surface 1 of Table 4B1. The incident angle of the light passing through the region 500 is 5 ^° to 20 ^° . In addition, the area 501 surrounded by the alternate long and short dash line in FIG. 14A is an effective area when the second time is incident on the R1 surface of L1, and corresponds to the surface 5 of Table 4B1. The incident angle of the light passing through the region 501 is 35 ^° to 50 ^° . A region 502 surrounded by a two-dot chain line shown in FIG. 14A is an effective region when the third time is incident on the R1 surface of the lens L1. Corresponds to face 7 of Table 4B1. The incident angle of the light passing through the region 502 is 35 ^° to 50 ^° . The area 503 surrounded by the solid line of FIG. 14B is an area including the areas 500, 501, and 502. The optical film of the optical film design example 1 as shown in Table 8A can be provided in the region 503.

The optical film design example 1 is an antireflection film having a three-layer structure using a dielectric material. A thin layer of Al ₂ O ₅ , ZrO ₂ , MgF ₂ is sequentially stacked on the SiO ₂ as the substrate layer. The film thickness of each layer is set to the value described in the table. Here, it is represented by the product nd of the refractive index n corresponding to the film species and the physical thickness d of the film.

Fig. 15A shows the reflectance characteristics of the optical film design example 1. It has a reflectance of 2% or less at a wavelength of 350 nm to 450 nm, an incident angle of 5 ^° to 20 ^°, and 35 ^° to 50 ^° .

(anti-reflection film 2)
It is also possible to provide the optical film of the optical film design example 2 as shown in Table 8B in the region 503.

The optical film design example 2 is an antireflection film having a seven-layer structure using a dielectric material. Fig. 15B shows the reflectance characteristics of the optical film design example 2. It has a reflectance of 1% or less at a wavelength of 350 nm to 450 nm, an incident angle of 5 ^° to 20 ^°, and 35 ^° to 50 ^° . In the optical film design example 2, the effect of increasing the number of layers of the film suppressed the reflectance as compared with the optical film design example 1 of the three-layer structure.

(anti-reflection film 3 and 4)
A region 505 surrounded by a solid line described in FIG. 14C is a region including the region 500. In addition, the area 506 surrounded by the solid line of FIG. 14C is an area including the area 501 and the area 502. The optical film design example 3 as shown in Table 8C1 was attached to the region 505, and the optical film design example 4 as shown in Table 8C2 was attached to the region 505.

Each of the optical film design examples 3 and 4 is an antireflection film having a three-layer structure using a dielectric material. Fig. 15C1 shows the reflectance characteristics of the optical film design example 3, and Fig. 15C2 shows the reflectance characteristics of the optical film design example 4.

The optical film of Example 3 having a design wavelength of 350nm ~ 450nm, the incident angle is 1% or less of the reflection characteristics when 5 ^° ~ 20 ^°. Further, the optical film of Example 4 having a design wavelength of 350nm ~ 450nm, the incident angle is 1% or less of the reflection characteristics when 35 ^° ~ 50 ^°.

In this way, an optical film having a different type depending on the region is attached to the R1 surface of the lens L1. The antireflection films 1 to 4 are an example, and the material, the number of layers, the film thickness, and the like of the film are not limited to this example.

The antireflection film described in the present specification has been described by irradiating a light spot on the R1 surface of the lens L1. However, the antireflection film should be originally applied to the incident surface or the exit surface of the optical element. Therefore, in the case where there are a plurality of optical elements, it is preferable to optimize the structure of the film so that the respective surfaces satisfy the desired optical characteristics. Further, as for the optically reflective member, it is preferable to constitute a reflective film (such as a film having a high reflectance at a desired wavelength) instead of constituting the antireflection film.

160‧‧‧Reflective refracting optical system

OBJ‧‧‧ surface

IMG‧‧‧face

L1, L2‧‧ lens

M1～M4‧‧·Mirror

FIG. 1 is a view showing a configuration of an illumination optical system according to an embodiment of the present invention.

FIG. 2 is a view showing a schematic configuration of a fly-eye optical system.

3 is a view showing a schematic configuration of a field stop.

4A is a view showing the structure of a catadioptric optical system of Design Example 1.

4B is a developed view of the catadioptric optical system of Design Example 1.

4C is a graph showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 1.

4D is a view showing illumination light that is shaped into an arc shape.

FIG. 5A is a view showing a structure of a catadioptric optical system of Design Example 2. FIG.

Fig. 5B is a development view of the catadioptric optical system of Design Example 2.

5C is a graph showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 2.

Fig. 6A is a view showing the structure of a catadioptric optical system of Design Example 3.

Fig. 6B is a development view of the catadioptric optical system of Design Example 3.

6C is a graph showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 3.

Fig. 7A is a view showing the structure of a catadioptric optical system of Design Example 4.

7B is a development view of a catadioptric optical system of Design Example 4.

Fig. 7C is a graph showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 4.

8A is a view showing the structure of a catadioptric optical system of Design Example 5.

8B is a developed view of a catadioptric optical system of Design Example 5.

8C is a graph showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 5.

9A is a view showing the structure of a catadioptric optical system of Design Example 6.

9B is a developed view of a catadioptric optical system of Design Example 6.

9C is a graph showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 6.

FIG. 10 is a view showing a configuration of an exposure apparatus according to an embodiment of the present invention.

Fig. 11 is a view for explaining illuminance measurement.

12A and 12B are diagrams for explaining illuminance unevenness correction.

Fig. 13A is a view showing the structure of a catadioptric optical system of Design Example 7.

Fig. 13B is a development view of the catadioptric optical system of Design Example 7.

FIG. 13C is a view showing the degree of sharing of the Petzval sum of the catadioptric optical system of Design Example 7. FIG.

Fig. 14A is a view showing an effective area of a light beam.

Fig. 14B is a view showing a region in which the optical film design example 1 or 2 is mounted.

Fig. 14C is a view showing a region in which the optical film design examples 3 and 4 are mounted.

Fig. 15A is a view showing optical characteristics of an optical film design example 1.

Fig. 15B is a view showing optical characteristics of the optical film design example 2.

Fig. 15C is a view showing optical characteristics of the optical film design example 3.

Fig. 15D is a view showing optical characteristics of the optical film design example 4.

Claims (16)

A catadioptric optical system that directs light emitted from a surface toward an image plane, contain: a first reflecting surface, a second reflecting surface, a third reflecting surface, and a fourth reflecting surface; and a refractive surface having a positive refractive power disposed between the object surface and the first reflecting surface; When the third-order Perzian term of the refractive surface having the positive refractive power is P(L1), and the third-order Petzval sum of the catadioptric optical system is P(sum), it is in accordance with | P(sum)|<|P(L1)|. The catadioptric optical system according to claim 1, wherein the catadioptric optical system is an optical system of one-time imaging having an imaging surface only on the image plane. A catadioptric optical system according to claim 1, wherein the refractive surface is composed of one lens. The catadioptric optical system of claim 1, wherein the refractive surface is composed of at least two lenses. The catadioptric optical system according to claim 1, wherein two refractive surfaces including the refractive surface are disposed between the object surface and the first reflecting surface. The catadioptric optical system according to claim 1, wherein the refractive surface having a positive refractive power has an aspherical shape. The catadioptric optical system according to claim 1, wherein at least one of the first reflecting surface, the second reflecting surface, the third reflecting surface, and the fourth reflecting surface has an aspherical shape. The catadioptric optical system according to claim 1, wherein the object surface side and the image surface side are telecentric. The catadioptric optical system according to claim 8, wherein the pupil position of the catadioptric optical system is located between the first reflecting surface and the second reflecting surface. The catadioptric optical system according to claim 8, wherein at least one of the vicinity of the object surface and the vicinity of the image surface is provided with an aspherical lens for correcting telecentricity. The catadioptric optical system according to claim 1, wherein the total length of the catadioptric optical system is TT, and when the distance between the object surface and the refractive power surface closest to the object surface is S1, the S1/TT is satisfied. >0.1. The catadioptric optical system according to claim 1, wherein a distance from the object surface to a refractive power surface closest to the object surface is S1, and a distance from the final refractive power surface to the image surface is Sk. , in line with Sk/S1<3.0. The catadioptric optical system according to claim 1, wherein the optical film formed on the refractive surface disposed between the object surface and the first reflecting surface is formed on the second reflecting surface and the first surface 3 The types of optical films on the refractive surface between the reflecting surfaces are different from each other. An illumination optical system having a catadioptric optical system according to any one of claims 1 to 13. An exposure apparatus comprising an illumination optical system that illuminates an original plate through light from a light source, and a projection optical system that projects the pattern of the original plate onto a substrate. The illumination optical system comprising: a slit having a transmissive portion that transmits light from the light source; and transflecting the slit through the catadioptric optical system according to any one of claims 1 to 13 The light is illuminated in the aforementioned original. An article manufacturing method, contain: a procedure for exposing a substrate through an exposure apparatus as claimed in claim 15; and a program for developing the aforementioned substrate; An article is manufactured from the aforementioned substrate.