TWI701458B - Catadioptric optical system, illumination optical system, exposure device and article manufacturing method - Google Patents

Abstract

The invention relates to a catadioptric optical system, an illumination optical system, and an exposure device. The catadioptric optical system that is telecentric on the object and image planes includes: a first reflective surface, a second reflective surface, a third reflective surface, and a fourth reflective surface; and a refractive surface with positive refractive power, and the refractive surface is disposed on Between the object surface and the first reflecting surface, light emitted from the object surface sequentially passes through the refracting surface, the first reflecting surface, the refracting surface, the second reflecting surface, the refracting surface, and the third reflecting surface. The fourth reflecting surface reaches the image surface.

Description

Catadioptric optical system, illumination optical system, exposure device and article manufacturing method

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

The exposure device is a device that transfers the pattern of the original plate to a photosensitive substrate (a substrate with a photoresist layer formed on the surface) via a projection optical system in a photolithography process for manufacturing semiconductor devices, display devices, and the like. For example, an exposure device used to manufacture a display device requires performance that can transfer a pattern to a larger area substrate with high resolution. In order to meet such a demand, a scanning exposure device that can obtain high resolution and can perform exposure on a large screen is useful. The scanning exposure device scans the original plate and the substrate while exposing the substrate with light that is shaped into an arc. At this time, the original plate is illuminated with light shaped into an arc shape, and the pattern of the original plate is projected onto the substrate by the light shaped into an arc shape.

Patent Document 1 describes an illuminating optical system that illuminates an original plate with light shaped like an arc. However, in order to illuminate an object with uniform energy in a desired shape, an imaging optical system that images the object on the opening of the field diaphragm provided in the illumination optical system is required. Generally speaking, such an imaging optical system is called a shielded imaging system. In the case of illuminating a large screen, in order to reduce the size of the optical elements around the field diaphragm as much as possible, the shadow imaging system is preferably composed of a mirror system with a 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 offner optical system and uses three curvature mirrors to bend light to form an image. The Offner optical system is an equal magnification system for one-shot imaging, but as described in Patent Document 3, magnification can be achieved according to the positions of three curvature mirrors. In addition, as described in Patent Document 4, there are optical systems that use multiple imaging to correct aberrations. [Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Publication No. 04-078002 Patent Document 2: Japanese Patent Application Publication No. 2010-20017 Patent Document 3: Japanese Patent Application Publication No. 07-146442 Patent Document 4: Japanese Patent Application Publication No. 61-203419

However, since the imaging optical systems described in Patent Documents 2 and 3 have a long back focal length, for example, when they are mounted on an exposure device, the exposure device will increase in size. In addition, since the optical system described in Patent Document 4 performs multiple imaging, the overall length becomes longer, resulting in an increase in the size of the device.

An object of the present invention is to provide a catadioptric optical system that is compact and has a structure that is advantageous for reducing aberrations, and an apparatus including the catadioptric optical system.

The first aspect of the present invention relates to a catadioptric optical system telecentric on the object plane and the image plane, the catadioptric optical system including: a first reflective surface, a second reflective surface, a third reflective surface, and a fourth reflective surface; and A refractive surface with positive refractive power, which is arranged between the object surface and the first reflective surface, and light exiting from the object surface sequentially passes through the refractive surface, the first reflective surface, the refractive surface, The second reflective surface, the refractive surface, the third reflective surface, and the fourth reflective surface reach the image surface. The second aspect of the present invention relates to an illumination optical system, and the illumination optical system has the catadioptric optical system as in the first aspect. A third aspect of the present invention relates to an exposure device, and the exposure device has the catadioptric optical system as in the first aspect. A fourth aspect of the present invention relates to an article manufacturing method. The article manufacturing method includes the following procedures: exposing a substrate with the exposure device as in the third aspect; and developing the substrate; wherein the article is manufactured from the substrate.

According to the present invention, a catadioptric optical system that is compact and has a structure that is advantageous for reducing aberrations and a device including the catadioptric optical system are provided.

Hereinafter, referring to the drawings, the present invention will be described through its exemplary embodiments.

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

The light source 101 may be, for example, a high-pressure mercury lamp, a xenon lamp, or an excimer laser. The elliptical mirror 102 is a condensing optical system for condensing the light emitted from the light source 101, and has a shape using a part of an elliptical shape. The light source 101 can be arranged at one of the two focal points of the elliptical mirror 102 (the first focal point).

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

The first optical system 105 is configured such that the surface 108 substantially becomes a Fourier transformed position with respect to the light exiting the second focal point of the elliptical mirror 102. The light from the Fourier transform plane 108 is guided to the fly-eye optical system 109 by the second optical system 140. The second optical system 140 is configured such that the incident surface of the fly-eye optical system 109 substantially becomes a Fourier transform position with respect to the surface 108.

In Fig. 2, a fly-eye optical system 109 is shown. As shown in FIG. 2, the fly-eye optical system 109 may include two lens groups 131 and 132. Each lens group can be configured by arranging a plurality of plano-convex lenses on a plane. The plano-convex lens constituting the lens group 132 is arranged at the focal position of the plano-convex lens constituting the lens group 131. In addition, 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 fly-eye optical system 109.

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

FIG. 3 illustrates the shape of the field diaphragm 111. The field diaphragm 111 blocks light other than the arc-shaped transmission part 23. The light shaped into an arc shape by the field stop 111 uniformly illuminates the original plate M via the fourth optical system 160. The shape of the opening of the field diaphragm 111 is not limited to the arc shape, and may be another shape. The opening of the field diaphragm 111 may have, for example, a rectangular shape that is inscribed to the arc shape. The fourth optical system 160 is a catadioptric optical system. Hereinafter, the fourth optical system 160 will be described as a 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 reflecting mirror (first reflecting surface) M1, a second reflecting mirror (second reflecting surface) M2, a third reflecting mirror (third reflecting surface) M3, and a fourth reflecting mirror (fourth Reflecting surface) M4. In addition, the catadioptric optical system 160 may include a refractive surface with positive refractive power disposed between the object surface OBJ and the first mirror M1. The refractive surface can be constituted by the lens L1. The light from the object surface OBJ sequentially passes through the refractive surface, the first mirror M1, the refractive surface, the second mirror M2, the refractive surface, the third mirror M3, and the fourth mirror M4 to the image surface IMG. .

The refractive surface may be composed of one lens L1 or at least two lenses. In the latter, the respective surfaces of at least two lenses may constitute mutually different regions in the refractive surface. The lens L1 may have two refractive surfaces. The refractive surface may have an aspheric shape. The refractive surface may be configured such that when the third-order Petzval term is set to P(L1), and the third-order Petzval sum of the entire catadioptric optical system is set to P(sum), satisfying | 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 may be configured to not have an imaging surface between the object surface OBJ and the image surface IMG. In other words, the catadioptric optical system 160 may be an optical system that only has an imaging surface on the image surface IMG for one-shot imaging.

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 surface OBJ is S1. 0.1. The catadioptric optical system 160 may be configured such that the distance from the object surface OBJ to the refractive power surface closest to the object surface OBJ is set to S1, and the distance from the final refractive power surface to the image surface IMG is set to Sk. When, it satisfies Sk/S1<3.0.

The catadioptric optical system 160 may 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 may 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 aspheric 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 of the image plane IMG of the catadioptric optical system 160, which is 0.09 in Design Example 1. The exposure width, slit width, and arc R are parameters that define the shape of the illumination light at the image plane IMG of the fourth optical system 160, and are 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 surface, d (mm) is the surface interval, and n is the glass material. Here, the refractive index of air is set to 1, and the surface that becomes -1 represents a reflective surface. SiO ₂ stands for synthetic quartz. In addition, the center of curvature of each surface is located on the optical axis.

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

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

The light beam from the object plane OBJ with a predetermined NA passes through L1 (surface number 1, 2), M1 (surface number 3), L1 (surface number 4, 5), M2 (surface number 6), L1 in order from OBJ (Face number 7, 8), M3 (face number 9), M4 (face number 10) and imaged on 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 a development view of the catadioptric optical system 160 of Design Example 1. FIG. The total length TT and S1, Sk of the catadioptric optical system 160 are defined as shown in FIG. 4B. The expanded view is a reference diagram for making the overall refractive power configuration of the catadioptric optical system 160 easy to understand. The actual catadioptric optical system 160 has a mirror. In FIG. 4B, the mirror is represented by a thin lens equivalent to it. This point is common in FIGS. 5B, 6B, 7B, 8B, and 9B.

FIG. 4C shows the three-order Petzval terms of L1, M1, M2, M3, and M4, and the total three-order Petzval sum (SUM) of the catadioptric optical system 160. Here, the Petzval 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 3 Petzval terms of L1, M1, M2, M3, and M4.

Table 1C shows the total length TT, S1, and Sk of the catadioptric optical system 160 of Design Example 1.

The total length TT of the catadioptric optical system 160 is a simple sum of the intervals of the multiple surfaces from the object plane OBJ of the catadioptric optical system 160 to the image plane IMG. That is, the total length TT is a value obtained by integrating the absolute value of d in Table 1B. S1 is the 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 whose surface number is 1), and Sk is the distance from the final refractive power surface (closest to the image surface IMG) The distance from the refractive power surface of, that is, the surface with surface number 10) to the image surface IMG.

S1/TT is the ratio of S1 to TT, and if this value is large, for example, a plurality of field diaphragms can be arranged in the vicinity of the object plane OBJ, thereby increasing the degree of freedom of design. Sk/S1 is the ratio of Sk to S1. When the catadioptric optical system 160 is a magnifying system, it can be said that the smaller the value, the more compact the optical system.

Table 1D shows the optical performance 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. In addition, the spot RMS represents the worst value of the RMS spot diameter within the effective area, dist represents distortion, and the telecentricity (range) represents the deviation of the telecentricity in the slit width direction.

As in the design example 1, the light beam from the object surface OBJ passes through the lens L1 three times. If the area where the light beam passes through the lens L1 for the first time and the area where the light beam passes through the lens L1 for the second time do not overlap, it is not necessary to use the same lens L1. However, when the NA of the image plane IMG is large, the magnification is small, or the like, the same lens L1 needs to be used when it is difficult to separate regions where the light beam passes through. (Design example 2) Table 2A shows the optical specifications of Design Example 2.

The wavelength of light is 365nm～435nm, and 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 represents an aspheric surface, and its shape is expressed as a function of h as in equation (1) using the numerical value described in Table 2B2. In formula (1), h is the distance from the optical axis, and Z is the position in the optical axis direction.

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

The light beam from the object plane OBJ with a predetermined NA passes through L2 (surface number 1, 2), L1 (surface number 3, 4), M1 (surface number 5), L1 (surface number 6, 7) in order from OBJ , M2 (face number 8), L1 (face number 9, 10), M3 (face number 11), M4 (face number 12). The beam is then 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. 5B shows a development view of the catadioptric optical system 160 of Design Example 2. FIG. FIG. 5C shows the three-order Petzval terms of L1, L2, M1, M2, M3, and M4 and the total three-order Petzval sum (SUM) of the catadioptric optical system 160.

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

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

The catadioptric optical system 160 of Design Example 2 has a smaller telecentricity (range) value than that of the catadioptric optical system 160 of Design Example 1. This is because the range is corrected by the aspheric lens L2 having negative refractive power.

In Design Example 2, the aspheric lens L2 is arranged near the object surface OBJ, but the aspheric lens L2 may be arranged near the image surface IMG. That is, the aspheric lens may be arranged at least one of the vicinity of the object surface OBJ and the vicinity of the image surface IMG. Among them, in the case of the magnification system, the effective diameter of the optical element near the image plane IMG becomes larger, so it is preferable to arrange it near the object plane OBJ if possible. (Design Example 3) Table 3A shows the optical specifications of Design Example 3.

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

ASPs with surface numbers 2, 4, and 8 represent aspheric surfaces, and their shape is defined by the aforementioned formula (1). 6A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 3. OBJ stands for object plane, and IMG stands for image plane. L1 is a lens with positive refractive power and has two refractive surfaces. The total refractive power of the two refractive surfaces has a positive refractive power. Therefore, at least one refractive surface has positive refractive power. M1 is the first reflecting mirror (first reflecting surface), M2 is the second reflecting mirror (second reflecting surface), M3 is the third reflecting mirror (third reflecting surface), and M4 is the fourth reflecting mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflection surfaces) with positive refractive power, M2 is mirrors (reflection surfaces) with negative refractive power, and M3 is a plane mirror.

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

FIG. 6B shows a development view of the catadioptric optical system 160 of Design Example 3. FIG. FIG. 6C shows the three-order Petzval terms of L1, M1, M2, M3, and M4 and the total three-order Petzval sum (SUM) of the catadioptric optical system 160.

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

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

The catadioptric optical system 160 of Design Example 3 has a larger value of S1/TT than the catadioptric optical system 160 of Design Examples 1 and 2. With the aspheric lens L2, the aberration and telecentricity of the optical system are well corrected, so that the refractive power configuration such as increasing S1 can be performed. (Design Example 4) Table 4A shows the optical specifications of Design Example 4.

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

ASPs with surface numbers 2, 4, 8, and 9 represent aspheric surfaces, and their shape is defined by the aforementioned formula (1). FIG. 7A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 4. FIG. OBJ stands for object plane, and IMG stands for image plane. L1 is a lens with positive refractive power and has two refractive surfaces. The total refractive power of the two refractive surfaces has a positive refractive power. Therefore, at least one refractive surface has positive refractive power. M1 is the first reflecting mirror (first reflecting surface), M2 is the second reflecting mirror (second reflecting surface), M3 is the third reflecting mirror (third reflecting surface), and M4 is the fourth reflecting mirror (fourth reflecting surface) ). M1, M3, and M4 are mirrors (reflection surfaces) having positive refractive power, and M2 are mirrors (reflection surfaces) having negative refractive power.

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

FIG. 7B shows a development view of the catadioptric optical system 160 of Design Example 4. FIG. FIG. 7C shows the three-order Petzval terms of L1, M1, M2, M3, and M4, and the total three-order Petzval sum (SUM) of the catadioptric optical system 160. Table 4C shows the total length TT, S1, Sk, S1/TT, and Sk/S1 of the catadioptric optical system 160 of Design Example 4.

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

The catadioptric optical system 160 of Design Example 4 has a shorter total length TT than the catadioptric optical system 160 of Design Example 1. The aspheric lens L1 and the aspheric mirror M3 are used to well correct the aberration and telecentricity of the catadioptric optical system 160, thereby enabling a compact refractive power configuration as a whole to be realized. (Design Example 5) Table 5A shows the optical specifications of Design Example 5.

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

ASPs with surface numbers 2, 4, 8, and 9 represent aspheric surfaces, and their shape is defined by the aforementioned formula (1). FIG. 8A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 5. FIG. Shows a cross-sectional view of the optical system. OBJ stands for object plane, and IMG stands for image plane. L1 is a lens with positive refractive power and has two refractive surfaces. The total refractive power of the two refractive surfaces has a positive refractive power. Therefore, at least one refractive surface has positive refractive power. M1 is the first reflecting mirror (first reflecting surface), M2 is the second reflecting mirror (second reflecting surface), M3 is the third reflecting mirror (third reflecting surface), and M4 is the fourth reflecting mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) with positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) with negative refractive power.

The light beam from the object plane OBJ with a predetermined NA passes through L1 (surface number 1, 2), M1 (surface number 3), L1 (surface number 4, 5), M2 (surface number 6), L1 in order from OBJ (Face number 7, 8), M3 (face number 9), M4 (face number 10) and imaged on IMG. The pupil of the catadioptric optical system 160 may also be located in the vicinity of 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. FIG. 8C shows the three-order Petzval terms of L1, M1, M2, M3, and M4 and the total three-order Petzval sum (SUM) of the catadioptric optical system 160. FIG. 8B shows an expanded view of the catadioptric optical system 160 of Design Example 5. FIG. 8C shows the 3rd Petzval terms of L1, M1, M2, M3, and M4, and the 3rd Petzval sum (SUM) of the whole catadioptric optical system 160.

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

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

The catadioptric optical system 160 of Design Example 5 has a smaller value of Sk/S1 than the catadioptric optical system 160 of Design Example 4. This is because the value of NAil is larger than that of Design Example 4. Therefore, in order to separate the light reflected by M3 from the light from M4 toward the image surface IMG, M4 is moved to the image surface IMG side. (Design Example 6) Table 6A shows the optical specifications of Design Example 6.

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

ASPs with surface numbers 2, 4, 8, and 9 represent aspheric surfaces, and their shape is defined by the aforementioned formula (1). FIG. 9A shows a cross-sectional view of the catadioptric optical system 160 of Design Example 6. FIG. OBJ stands for object plane, and IMG stands for image plane. L1 is a lens with positive refractive power and has two refractive surfaces. The total refractive power of the two refractive surfaces has a positive refractive power. Therefore, at least one refractive surface has positive refractive power. M1 is the first reflecting mirror (first reflecting surface), M2 is the second reflecting mirror (second reflecting surface), M3 is the third reflecting mirror (third reflecting surface), and M4 is the fourth reflecting mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) with positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) with negative refractive power.

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

FIG. 9B shows a development view of the catadioptric optical system 160 of Design Example 6. FIG. FIG. 9C shows the three-order Petzval terms of L1, M1, M2, M3, and M4 and the total three-order Petzval sum (SUM) of the catadioptric optical system 160.

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

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

The catadioptric optical system 160 of Design Example 6 has a smaller value of Sk/S1 than the catadioptric optical system 160 of Design Example 4. This is because the value of NAil is larger than that of Design Example 4. Therefore, in order to separate the light reflected by M3 from the light from M4 toward the image surface IMG, M4 is positioned closer to the image surface. (Exposure device) FIG. 10 shows the structure of an exposure apparatus 400 according to an embodiment of the present invention. The exposure device 400 includes an illumination optical system 100, and scans and exposes a substrate using slit light from the illumination optical system 100. The illumination optical system 100 includes a slit mechanism 181 capable of adjusting the shape of the opening.

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

The exposure apparatus 400 may further include a measurement section 304 that measures the illuminance distribution of the light reaching the substrate stage 302 through the measurement section 304 to measure unevenness of illuminance in the exposure area of the substrate. In addition, the slit plate 303 is located between the substrate stage 302 and the measurement unit 304. The slit plate 303 can be scanned and driven in the exposure width direction of FIG. 4D by a driving part (not shown) under the control of a control part (not shown).

As shown in FIG. 10, the measurement unit 304 may include a sensor 305 and an optical system for guiding the 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 area 401 of the light imaged on the substrate stage 302. At this time, out of the light formed in the area 401, only the light formed in the opening 306 of the slit plate 303 enters the measurement unit 304. The light incident in the measurement unit 304 is guided to the sensor 305 via the optical system. The illuminance of 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 uneven illumination can be calculated.

As described above, by adjusting the opening width of the slit mechanism 181 included in the illumination optical system 100, uneven illumination 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, by locally increasing the width of the slit mechanism 181 in the portion where the illuminance decreases, and locally narrowing the width of the slit mechanism 181 in the portion where the illuminance increases, the illuminance distribution can be made uniform as shown in FIG. 12B.

The article manufacturing method of one embodiment of the present invention may include an exposure process of exposing a substrate using the exposure device 400 and a development process of developing the substrate. The substrate exposed in the exposure process has a photoresist on the surface, and the latent image of the pattern of the original plate can be formed on the photoresist during the exposure process. In the development process, the latent image can be developed to form a resist pattern. After the development process, for example, the substrate may be etched through the resist pattern, or ions may be implanted into the substrate. The articles that can be formed in this way include, for example, display devices (display panels), semiconductor devices (semiconductor wafers), and the like. (Design Example 7) Table 7A shows the optical specifications of Design Example 7.

The light wavelength is 335nm～405nm, and 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 a catadioptric optical system 160 of Design Example 7. FIG. OBJ stands for object plane, and IMG stands for image plane. L1 and L2 are lenses with positive refractive power and have two refractive surfaces. The total refractive power of the two refractive surfaces has a positive refractive power. Therefore, at least one refractive surface has positive refractive power. M1 is the first reflecting mirror (first reflecting surface), M2 is the second reflecting mirror (second reflecting surface), M3 is the third reflecting mirror (third reflecting surface), and M4 is the fourth reflecting mirror (fourth reflecting surface) ). M1 and M4 are mirrors (reflecting surfaces) with positive refractive power, and M2 and M3 are mirrors (reflecting surfaces) with negative refractive power.

The light beam from the object plane OBJ with a predetermined NA passes through L1 (surface number 1, 2), M1 (surface number 3), L2 (surface number 4, 5), M2 (surface number 6), L2 in order from OBJ (Face number 7, 8), M3 (face number 9), M4 (face number 10) and imaged on 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 a development view of the catadioptric optical system 160 of Design Example 6. FIG. FIG. 13C shows the three-order Petzval terms of L1, L2, M1, M2, M3, and M4 and the total three-order Petzval sum (SUM) of the catadioptric optical system 160.

L1 and L2 of Design Example 7 are just examples, and they are not limited to the current example as long as they are lenses each having a positive refractive power.

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

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

L1 and L2 of Design Example 7 are just examples, and they are not limited to the current example as long as they are lenses each having a positive refractive power. (Anti-reflective film 1) The anti-reflection film of the lens L1 formed in the catadioptric optical system 160 of Design Example 4 will be described.

As shown in Fig. 7A, the light beam from the object surface OBJ with a predetermined NA passes through L1 (surface number 1, 2), M1 (surface number 3), L1 (surface number 4, 5), M2 (surface number Number 6), L1 (face number 7, 8), M3 (face number 9), M4 (face number 10). Then, the beam is then imaged on the IMG.

FIG. 14A is a diagram obtained by viewing the R1 surface (the surface close to the OBJ side) of the lens L1 from the OBJ side. The area 500 enclosed by the dotted line in FIG. 14A is the effective area when the light beam from the OBJ first enters the R1 surface of L1, and corresponds to the surface 1 of Table 4B1. The incident angle of the light passing through the area 500 is 5 ^° -20 ^° . In addition, the area 501 enclosed by the dashed-dotted line in FIG. 14A is the effective area when it is incident on the R1 surface of L1 for the second time, and corresponds to the surface 5 of Table 4B1. The incident angle of the light passing through the area 501 is 35 ^° -50 ^° . The area 502 enclosed by the two-dot chain line described in FIG. 14A is the effective area when the lens L1 is incident on the R1 surface for the third time. It is equivalent to face 7 of Table 4B1. The surface incident angle of the light passing through the area 502 is 35 ^° -50 ^° . A region 503 surrounded by a solid line in FIG. 14B is a region including regions 500, 501, and 502. The optical film of Optical Film Design Example 1 as shown in Table 8A can be installed in the region 503.

The optical film design example 1 is an anti-reflection film of a three-layer structure using a dielectric material. A thin layer of Al ₂ O ₅ , ZrO ₂ , and MgF ₂ is sequentially stacked on SiO ₂ as the substrate layer. The film thickness of each layer was 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 type and the physical thickness d of the film.

FIG. 15A shows the reflectance characteristics of optical film design example 1. FIG. It has a characteristic that the reflectance is 2% or less when the wavelength is 350nm-450nm, the incident angle is 5 ^° -20 ^°, and 35 ^° -50 ^° . (Anti-reflection film 2) The optical film of the optical film design example 2 shown in Table 8B may be provided in the area 503.

The optical film design example 2 is an anti-reflection film with a 7-layer structure using a dielectric material. FIG. 15B shows the reflectance characteristics of the optical film design example 2. FIG. It has a characteristic that the reflectance is less than 1% when the wavelength is 350nm-450nm, the incident angle is 5 ^° -20 ^°, and 35 ^° -50 ^° . The optical film design example 2 has the effect of increasing the number of layers of the film, and thus the reflectance is suppressed compared to the optical film design example 1 with a three-layer structure. (Anti-reflection films 3 and 4) The area 505 surrounded by a solid line described in FIG. 14C is an area including the area 500. In addition, the area 506 surrounded by the solid line in 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 area 505, and the optical film design example 4 as shown in Table 8C2 was attached to the area 505.

Optical film design examples 3 and 4 are anti-reflection films of a three-layer structure using dielectric materials, respectively. 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 design example 3 has a characteristic that the reflectance is 1% or less when the wavelength is 350 nm to 450 nm and the incident angle is 5 ^° to 20 ^° . In addition, the optical film design example 4 has characteristics of a reflectance of 1% or less when the wavelength is 350 nm to 450 nm and the incident angle is 35 ^° to 50 ^° .

In this way, different types of optical films are attached to the R1 surface of the lens L1 depending on the area. The anti-reflection films 1 to 4 are an example, and the material, number of layers, film thickness, etc. of the film are not limited to this example.

Regarding the antireflection film described in this specification, the R1 surface of the lens L1 is irradiated with a light spot, but the antireflection film should be applied to the incident surface or the exit surface of the optical element. Therefore, when there are a plurality of optical elements, it is preferable to optimize the structure of the film so as to satisfy the desired optical characteristics on each surface. In addition, with regard to the optical reflective member, it is preferable to form a reflective film (such as a film whose reflectance becomes higher at a desired wavelength) instead of forming an anti-reflection film.

160‧‧‧Refracting optical system OBJ‧‧‧Object IMG‧‧‧Image surface L1、L2‧‧‧lens M1～M4‧‧‧Mirror

Fig. 1 is a diagram showing the configuration of an illumination optical system according to an embodiment of the present invention. Fig. 2 is a diagram showing a schematic configuration of a fly-eye optical system. Fig. 3 is a diagram showing a schematic configuration of a field diaphragm. 4A is a diagram showing the structure of a catadioptric optical system of Design Example 1. FIG. 4B is a development view of the catadioptric optical system of Design Example 1. FIG. 4C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 1. FIG. Fig. 4D is a diagram showing the illuminating light shaped into a circular arc. 5A is a diagram showing the structure of a catadioptric optical system of Design Example 2. FIG. 5B is an expanded view of the catadioptric optical system of Design Example 2. FIG. 5C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 2. FIG. 6A is a diagram showing the structure of a catadioptric optical system of Design Example 3. FIG. 6B is an expanded view of the catadioptric optical system of Design Example 3. FIG. 6C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 3. FIG. 7A is a diagram showing the structure of a catadioptric optical system of Design Example 4. FIG. 7B is an expanded view of the catadioptric optical system of Design Example 4. FIG. FIG. 7C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 4. FIG. 8A is a diagram showing the structure of a catadioptric optical system of Design Example 5. FIG. 8B is an expanded view of the catadioptric optical system of Design Example 5. FIG. FIG. 8C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 5. FIG. 9A is a diagram showing the structure of a catadioptric optical system of Design Example 6. FIG. 9B is a development view of the catadioptric optical system of Design Example 6. FIG. 9C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 6. FIG. Fig. 10 is a diagram showing the configuration of an exposure apparatus according to an embodiment of the present invention. Fig. 11 is a diagram explaining illuminance measurement. 12A and 12B are diagrams illustrating correction of uneven illuminance. 13A is a diagram showing the structure of a catadioptric optical system of Design Example 7. FIG. 13B is an expanded view of the catadioptric optical system of Design Example 7. FIG. FIG. 13C is a diagram showing the sharing degree of the Petzval sum of the catadioptric optical system of Design Example 7. FIG. Fig. 14A is a diagram showing the effective area of the light beam. It is a figure which shows the area|region where the optical film design example 1 or 2 is mounted. FIG. 14C is a diagram showing areas where optical film design examples 3 and 4 are installed. 15A is a graph showing optical characteristics of optical film design example 1. FIG. 15B is a graph showing the optical characteristics of optical film design example 2. FIG. 15C is a graph showing the optical characteristics of optical film design example 3. FIG. 15D is a graph showing the optical characteristics of optical film design example 4. FIG.

OBJ‧‧‧Object

IMG‧‧‧Image surface

L1‧‧‧Lens

M1~M4‧‧‧Mirror

Claims (16)

A catadioptric optical system that directs the light emitted from the object surface toward the image surface, and includes: a first reflecting surface, a second reflecting surface, a third reflecting surface, and a fourth reflecting surface; and arranged on the object surface and the aforementioned A refractive surface with positive refractive power between the first reflective surfaces; the light emitted from the object surface passes through the refractive surface at least once, and at the same time sequentially passes through the first reflective surface, the second reflective surface, and the third reflective surface Surface and the fourth reflecting surface to reach the image surface, the third Petzval term on the refractive surface with positive refractive power is P(L1), and the third order of the whole catadioptric optical system When the Petzval sum is P(sum), it conforms to |P(sum)|<|P(L1)|. For example, the catadioptric optical system of the first item of the scope of patent application, wherein the catadioptric optical system is an optical system for primary imaging with only an imaging surface on the image surface. For example, the catadioptric optical system of the first item of the scope of patent application, wherein the aforementioned refractive surface is composed of a lens. Such as the catadioptric optical system of the first item in the scope of patent application, wherein the aforementioned refractive surface is composed of at least two lenses. For example, in the catadioptric optical system of the first item in the scope of the patent application, two refractive surfaces including the refractive surface are arranged between the object surface and the first reflective surface. Such as the catadioptric optical system of the first item of the scope of patent application, wherein the aforementioned refractive surface with positive refractive power has an aspherical shape. According to the catadioptric optical system of 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. For example, the catadioptric optical system of the first item of the scope of patent application, wherein the side of the object surface and the side of the image surface are telecentric. For example, the catadioptric optical system of item 8 of the scope of patent application, wherein the pupil position of the catadioptric optical system is located between the first reflecting surface and the second reflecting surface. For example, the catadioptric optical system of claim 8 further includes an aspheric lens for correcting telecentricity in at least one of the vicinity of the object surface and the vicinity of the image surface. Such as the catadioptric optical system of item 1 of the scope of patent application, in which, When the total length of the catadioptric optical system is TT, and the distance between the object surface and the refractive power surface closest to the object surface is S1, it conforms to S1/TT>0.1. Such as the catadioptric optical system of the first item of the patent application, wherein the distance from the object surface to the refractive power surface closest to the object surface is S1, and the distance from the final refractive power surface to the image surface is Sk , In line with Sk/S1<3.0. The catadioptric optical system as claimed in claim 1, wherein an optical film formed on a refractive surface arranged between the object surface and the first reflecting surface, and an optical film formed on the second reflecting surface and the first reflecting surface 3 The types of the optical film of the refractive surface between the reflective surfaces are different from each other. An illumination optical system having a catadioptric optical system as in any one of items 1 to 13 in the scope of the patent application. 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 on a substrate, the illumination optical system: having a slit, the slit having A transmissive part that transmits light from the aforementioned light source; through a catadioptric optical system as in any one of the scope of the patent application, the light transmitted through the slit is illuminated on the aforementioned original plate. An article manufacturing method includes: a process of exposing a substrate through an exposure device as claimed in the scope of the patent application; and a process of developing the foregoing substrate; and manufacturing an article from the foregoing substrate.

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