JP2007005558A - Catadioptric projection optical system and exposure device having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catadioptric projection optical system which realizes exposure of high resolution and high quality, an exposure device with it, and a device manufacturing method. <P>SOLUTION: In the catadioptric projection optical system, an image of a first object is formed on a second object. The catadioptric projection optical system has a first imaging optical system for forming the first intermediate image of the first object, a second imaging optical system for forming the second intermediate image of the first object, based on light flux from the first intermediate image, a third imaging optical system for forming the third intermediate image of the first object, based on light flux from the second intermediate image, a fourth imaging optical system for forming the image of the first object on the second object, based on light flux from the third intermediate image, and two deflection reflection mirrors provided between the second and third imaging optical systems. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention generally relates to an imaging optical system, and in particular, catadioptric that projects and exposes an object to be exposed such as a single crystal substrate for a semiconductor wafer and a glass substrate for a liquid crystal display (LCD) using a reflecting mirror. The present invention relates to a mold projection optical system. The present invention is suitable, for example, for a so-called immersion exposure apparatus in which the final surface of the projection optical system and the surface of the object to be exposed are immersed in a liquid and the object to be processed is exposed through the liquid.

2. Description of the Related Art Projection exposure apparatuses that expose a circuit pattern drawn on a reticle (mask) onto a wafer or the like by a projection optical system have been used in the past. Yes. To increase the resolution, it is effective to shorten the wavelength of the exposure light and increase the NA of the projection optical system. Immersion exposure is attracting attention as a means for realizing high NA. In immersion exposure, the numerical aperture (NA) of the projection optical system is increased by making the medium on the wafer side of the projection optical system liquid. The NA of the projection optical system is NA = n · sin θ, where n is the refractive index of the medium, and therefore NA is increased to n by satisfying a medium having a refractive index higher than the refractive index of air (n> 1). be able to. As a result, the resolution R (R = k ₁ (λ / NA)) of the exposure apparatus expressed by the process constant k ₁ and the wavelength λ of the light source is to be reduced. In addition, aberration correction is important for realizing high-quality exposure. In particular, the glass materials that can be applied are limited due to the shortening of the wavelength of exposure light, making it difficult to correct chromatic aberration. For this reason, a catadioptric projection optical system that can easily correct chromatic aberration has been proposed (see, for example, Patent Documents 1 to 14). Such a catadioptric projection optical system is particularly effective in an environment with a high NA such as an immersion exposure apparatus.
JP-A-9-212332 JP-A-10-90602 US Pat. No. 5,650,877 JP-A-62-210415 JP-A-62-258414 JP 63-163319 A Japanese Patent Laid-Open No. 2-66510 JP-A-3-282527 JP-A-4-234722 Japanese Patent Laid-Open No. 5-188298 JP-A-6-230287 Japanese Patent Publication No. 8-304705 Japanese Patent Laid-Open No. 2002-83766 JP 2004-317534 A

  Although the catadioptric projection optical system is effective for aberration correction, it is necessary to increase the optical path length of the light beam for further aberration correction. This is because the amount of aberration generated in each partial system can be reduced by increasing the optical path length. However, since the environment in which the exposure apparatus is installed needs to be installed in a clean room due to problems such as temperature and air cleanliness, the total length of the apparatus itself is limited. In the immersion exposure apparatus, the direction perpendicular to the wafer surface must be parallel to the direction of gravity so that liquid does not spill. In order to prevent the reticle from undergoing its own weight deformation, the direction perpendicular to the reticle surface must also be parallel to the direction of gravity. On the other hand, the reflecting mirror that contributes to aberration correction in the catadioptric projection optical system is also preferably directed in the direction of gravity. If this is not done, the weight change of the reflecting mirror will not be uniform within the reflecting surface, and new aberration will occur. For this reason, it is preferable for the high-quality exposure that the aberration correcting reflector, reticle surface, and wafer surface are all directed in the direction of gravity. A configuration perpendicular to the wafer surface is not preferable. In order to prevent mechanical interference between the reticle stage that drives the reticle and the wafer stage that drives the wafer, it is more preferable that the reticle and the wafer can be arranged to face each other.

  Therefore, the present invention provides a catadioptric projection optical system that realizes high-resolution and high-quality exposure, an exposure apparatus having the same, and a device manufacturing method.

  A catadioptric projection optical system according to one aspect of the present invention is a catadioptric projection optical system that forms an image of a first object on a second object, and forms a first intermediate image of the first object. A first imaging optical system for forming, a second imaging optical system for forming a second intermediate image of the first object based on a light beam from the first intermediate image, and the second intermediate image. A third imaging optical system for forming a third intermediate image of the first object based on the luminous flux of the first object, and an image of the first object on the second object based on the luminous flux from the third intermediate image And a second deflecting mirror provided between the second and third imaging optical systems.

  A catadioptric projection optical system according to another aspect of the present invention is a catadioptric projection optical system that is an imaging system that forms an intermediate image of a first object a plurality of times and forms an image on the second object. The first and second object surfaces are arranged in parallel on opposite sides, the catadioptric projection optical system has two concave reflecting mirrors, and one of the two concave reflecting mirrors is the It is arranged to face one of the first and second object surfaces, and the other of the two concave reflecting mirrors is arranged to face the other of the first and second object surfaces. .

  An exposure apparatus according to another aspect of the present invention includes an illumination optical system that illuminates a pattern with light from a light source, and the above-described catadioptric projection optical system that projects light from the pattern onto a target object. It is characterized by having. A device manufacturing method according to another aspect of the present invention includes a step of exposing an object to be exposed using the above-described exposure apparatus, and a step of developing the exposed object to be exposed. The device manufacturing method claims also apply to the intermediate and final device itself. Such devices include semiconductor chips such as LSI and VLSI, CCDs, LCDs, magnetic sensors, thin film magnetic heads, and the like.

  Further objects and other features of the present invention will become apparent from the preferred embodiments described below with reference to the accompanying drawings.

  According to the present invention, there are provided a catadioptric projection optical system that realizes high-resolution and high-quality exposure, an exposure apparatus having the same, and a device manufacturing method.

  A catadioptric projection optical system 100 as one aspect of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic optical path diagram of the projection optical system. Reference numeral 101 denotes a first object (for example, a reticle), and reference numeral 102 denotes a second object (for example, a wafer). The projection optical system includes a first imaging system G1, a second imaging system G2, a deflection reflecting mirror FM1, a deflection reflecting mirror FM2, a third imaging system G3, and a fourth imaging system G4 in order from the object side. .

  The light beam from the first object 101 passes through the first imaging system G1 to form a first intermediate image. The light beam from the first intermediate image passes through the second imaging system G2 and is deflected by the deflecting / reflecting mirror FM1, and forms a second intermediate image before and after the deflecting / reflecting mirror FM1. The light beam from the deflecting mirror FM1 is deflected by the deflecting mirror FM2 and guided to the third imaging system G3. The light beam that has passed through the third imaging system G3 forms a third intermediate image and is guided to the fourth imaging system. The light beam that has passed through the fourth imaging system forms an image from the first object 101 on the second object 102 in a substantially telecentric manner. Such a four-time imaging system can secure a large optical path length, while the deflecting reflectors FM1 and FM2 can reduce the system, and there is no image inversion. It is desirable that some of the four image forming systems use not only a refractive system but also a concave reflecting mirror. This is because the concave reflecting mirror not only does not cause chromatic aberration but also has an effect of correcting the positive Petzval sum generated from the fourth imaging system G4 having a positive refractive power.

  The imaging optical systems G1 to G4 desirably have two or more pairs of catadioptric partial optical systems having concave reflecting mirrors and refractive optical systems consisting only of refractive members. This is because by providing a plurality of concave reflecting mirrors, the effect of correcting the Petzval sum is enhanced. Further, it is desirable that the concave reflecting mirrors are respectively disposed in the second imaging system G2 and the third imaging system G3. This is because the concave reflecting mirror needs to be arranged in an optical system in which the light beam reciprocates, and it is convenient to efficiently use the concave reflecting mirror and to make the entire optical system small. It is desirable not to configure the two concave reflecting mirrors on the same axis. Thereby, the sensitivity to inclination can be reduced. Further, it is desirable to arrange one concave reflecting mirror in parallel with the first object 101 and the other concave reflecting mirror in parallel with the second object 102. Since the concave reflecting mirror can be held uniformly against gravity, deformation of the concave reflecting mirror can be reduced, and most refractive lenses can be held in the same manner.

When the imaging magnification of the third imaging optical system G3 is β ₃ , the imaging magnification of the fourth imaging optical system G4 is β ₄ , and the numerical aperture of the entire system is NA, it is desirable to satisfy the following conditions: .

Formula 1 represents the opening angle of the light beam between the two deflecting reflectors FM1 and FM2. If Expression 1 is not satisfied, the deflecting reflectors FM1 and FM2 become large, and it becomes difficult to increase the self-weight deformation and manufacture of the deflecting reflectors FM1 and FM2. Further, when the distance of the focal point in the second intermediate image from the first deflecting mirror FM1 is A and the distance between the two deflecting mirrors FM1 and FM2 is B, it is desirable to satisfy the following conditions.

When Expression 2 is satisfied, the diameters of the two deflecting reflecting mirrors FM1 and FM2 can be balanced. If the size of one of the deflecting mirrors becomes large, the imaging performance deteriorates due to deformation of its own weight and the manufacture of the deflecting reflector becomes difficult. Furthermore, since the light rays concentrate at the position of the intermediate image, the temperature tends to be high. By placing a distance between the three intermediate images, it is possible to suppress the effects of various aberrations caused by heat and airflow generated in the vicinity of the intermediate image.

  It is desirable that there is no refractive member between the two deflecting mirrors FM1 and FM2. By not placing a refracting member between the deflecting mirrors, all optical members other than the deflecting mirrors can be kept almost horizontal, and asymmetrical shape change due to deformation of its own weight can be suppressed.

  When there is no refractive member between the two deflecting reflectors FM1 and FM2, when the angle between the optical axis and the principal ray of the outermost field angle between the two deflecting reflectors FM1 and FM2 is tel, It is desirable to satisfy the following conditions.

By satisfying Expression 3, it is possible to suppress an increase in the size of the deflecting mirror.

  Further, the projection optical system may have different light beam emission positions as shown in FIG. Here, FIG. 2 is a schematic optical path diagram of a modification of the projection optical system shown in FIG.

  A specific configuration of the first embodiment is shown in FIG.

  The first imaging optical system G1 as a refractive optical system includes optical elements L101 to L111 along the light traveling direction from the first object 101 side. Specifically, the first imaging optical system G1 includes a plane-parallel plate L101, a positive lens L102 and a positive lens L103 with an aspheric convex surface facing the second object 102 side. The first imaging optical system G1 further includes a meniscus lens L104 having a convex surface facing the first object 101, and a positive meniscus lens L105 having a concave aspheric surface facing the second object 102. The first imaging optical system G1 further includes a meniscus lens L106 having a concave aspheric surface facing the first object 101 and a meniscus lens L107 having a concave surface facing the first object 101. The first imaging optical system G1 further includes a positive meniscus lens L108 having a concave surface facing the first object 101 and a negative meniscus lens L109 having a convex aspheric surface facing the second object 102. The first imaging optical system G1 further includes a positive meniscus lens L110 having a concave surface facing the first object 101 and a positive meniscus lens L111 having a concave surface facing the first object 101. The light beam that has passed through the first imaging optical system G1 forms a first intermediate image. The first intermediate image is formed in the vicinity of the deflecting mirror FM1, thereby facilitating the separation of the light flux. The light beam from the first intermediate image is guided to the second imaging optical system G2.

  The second imaging optical system G2 includes optical elements L201 to L205 and a concave reflecting mirror M1 along the traveling direction of the light from the first imaging optical system G1. Specifically, the second imaging optical system G2 includes a positive meniscus lens L201 having a convex surface facing the first imaging optical system G1 and a positive aspheric surface facing the first imaging optical system G1. A meniscus lens L202. The second imaging optical system G2 further includes negative lenses L203 and L204, a negative meniscus lens L205 having a concave aspheric surface facing the first imaging optical system G1, and a concave reflecting mirror M1.

  The light beam reciprocating through the second imaging optical system G2 is deflected by the deflecting / reflecting mirror FM1 in the direction of approximately 45 ° with respect to the deflecting / reflecting mirror FM1, forms a second intermediate image, and is guided to the deflecting / reflecting mirror FM2. The light beam deflected by about 45 ° with respect to the deflecting reflecting mirror FM2 by the deflecting reflecting mirror FM2 is guided to the third imaging optical system G3.

  The third imaging optical system G3 includes optical elements L305 to L301 and a concave reflecting mirror M2 along the traveling direction of light from the deflecting reflecting mirror FM2. Specifically, the third imaging optical system G3 includes a positive lens L305 having a convex surface facing the deflecting mirror FM2 and a meniscus lens L304 having a convex surface facing the deflecting mirror FM2. The third imaging optical system G3 includes a positive meniscus lens L303 having a convex surface facing the deflecting mirror FM2, a negative meniscus lens L302 and a negative lens L301 having a concave surface facing the deflecting mirror FM2, and a concave reflecting mirror. M2. The light beam reciprocating through the third imaging optical system forms a third intermediate image. The third intermediate image is formed in the vicinity of the deflecting reflector FM2, thereby facilitating the separation of the light flux. The light beam from the third intermediate image is guided to the fourth imaging optical system G4.

  The fourth imaging optical system G4 includes optical elements L401 to L416 along the traveling direction of light from the third imaging optical system G3. More specifically, the fourth imaging optical system G4 has a positive meniscus lens L401 and a positive lens L402 having a concave surface facing the second object 102, and a concave aspherical surface facing the third imaging optical system G3. Negative meniscus lens L403. The fourth imaging optical system G4 includes a negative lens L404 having a concave aspheric surface facing the third imaging optical system G3, a meniscus lens L405 having a concave aspheric surface facing the second object 102, And a positive lens L406 having a convex surface facing the second object 102. The fourth imaging optical system G4 includes a negative meniscus lens L407 having a convex aspheric surface facing the third imaging optical system, positive lenses L408 and 409, and a positive surface having a concave surface facing the second object 102. Meniscus lenses L410, 411, and 412 are further included. The fourth imaging optical system G4 includes a positive meniscus lens L413 having a concave aspheric surface facing the second object 102, and a meniscus lens L414 having a convex aspheric surface facing the third imaging optical system G3. It has further. The fourth imaging optical system G4 further includes a meniscus lens L415 having a concave aspheric surface facing the second object 102, and a planoconvex lens L416 having a flat second object 102 side.

  In this embodiment, the numerical aperture on the image side is NA = 1.45, the reduction magnification is 1/4, and quartz is used for the glass material. The distance between the object images (the first object plane to the second object plane) is L = about 1870 mm. The light beam in the range of about 14.00 mm to 68.00 mm (the third imaging optical system G3 side is negative) of the height of the first object 101 is the second object without interference between the deflecting mirrors FM1 and FM2. An image is formed on 102. A rectangular exposure area of at least 26 mm in the length direction and about 7 mm in width can be secured.

  In the present embodiment and the following embodiments, the arrangement of the deflecting reflecting mirrors FM1 and FM2 is not limited to an angle of 45 ° with respect to the optical axis of the first imaging optical system G1. You may arrange | position at arbitrary angles with respect to an optical axis so that the light ray maximum incident angle to the deflection | deviation mirrors FM1 and FM2 may be made small. The deflecting mirrors FM1 and FM2 are preferably arranged in parallel to each other. Since the deflecting mirrors FM1 and FM2 do not contribute to aberration correction, the aberration of the entire system does not change, but the influence on the light incident angle characteristics of the reflecting film of the deflecting mirror and the imaging performance caused thereby, and the optical system This is advantageous in terms of shortening the overall length.

  Tables 1 to 5 show the specifications of the numerical embodiment of Example 1.

In the present embodiment and the following embodiments, the first column of the table represents surface numbers along the traveling direction of light from the first object 101. The second column represents the radius of curvature of each surface. The third column represents the axial spacing of each surface. The fourth column represents the refractive index with respect to the center wavelength. The radius of curvature is positive on the convex surface on the first object 101 side and negative on the convex surface on the second object 102 side. The axial distance between the surfaces is between the first object 101 and the concave reflecting mirror M1 of the second imaging optical system, between the deflecting reflecting mirror FM1 and the deflecting reflecting mirror FM2, and the concave reflecting of the third imaging system. A space between the mirror M2 and the second object 102 is represented by a positive interval. The distance between the concave reflecting mirror M1 and the deflecting reflecting mirror FM1 of the second imaging optical system and the distance between the deflecting reflecting mirror FM2 and the concave reflecting mirror M2 of the third imaging system are represented by negative intervals. The lens glass material SiO ₂ has a refractive index of 1.5609 with respect to the reference wavelength λ = 193 nm. Further, the refractive indexes of the wavelengths of +0.3 pm and −0.3 pm with respect to the reference wavelength are 1.5608895218 and 1.5609004782, respectively. The immersion material filled between the final lens and the image plane has a refractive index of 1.597 with respect to the reference wavelength λ = 193 nm. An aspherical surface is represented by ASP, and its shape is represented by the following equation.

Where X is the amount of displacement in the optical axis direction from the lens apex, h is the distance from the optical axis, ri is the radius of curvature, k is the conic constant, A, B, C, D, E, F, G, H, J is an aspheric coefficient. The reflecting surface is represented by REFL.

  A specific configuration of the second embodiment is shown in FIG.

  The first imaging optical system G1 of the refractive optical system includes optical elements L101 to L111 along the light traveling direction from the first object 101 side. More specifically, the first imaging optical system G1 includes a parallel plane plate L101, a positive lens L102 having an aspheric convex surface facing the second object 102, and a positive lens L103. The first imaging optical system G1 further includes a meniscus lens L104 having a convex surface facing the first object 101, and a positive meniscus lens L105 having a concave aspheric surface facing the second object 102. The first imaging optical system G1 includes a positive meniscus lens L106 having a concave aspheric surface facing the first object 101, a meniscus lens L107 having a concave surface facing the first object 101, and the first object 101 side. And a positive meniscus lens L108 having a concave surface facing the surface. The first imaging optical system G1 includes a negative meniscus lens L109 having a positive aspheric surface facing the second object 102, a positive meniscus lens L110 having a concave surface facing the first object 101, and a positive lens L111. It has further. The light beam that has passed through the first imaging optical system G1 forms a first intermediate image. The first intermediate image is formed in the vicinity of the deflecting mirror FM1, thereby facilitating the separation of the light flux. The light beam from the first intermediate image is guided to the second imaging optical system G2.

  The second imaging optical system G2 includes optical elements L201 to L205 and a concave reflecting mirror M1 along the traveling direction of the light from the first imaging optical system G1. More specifically, the second imaging optical system G2 has a positive meniscus lens L201 having a convex surface facing the first imaging optical system G1 and a convex aspheric surface facing the first imaging optical system G1. It has a positive meniscus lens L202 and a concave lens L203. The second imaging optical system G2 includes a negative meniscus lens L204 having a concave surface facing the first imaging optical system G1 and a negative meniscus lens L205 having a concave aspheric surface facing the first imaging optical system G1. And a concave reflecting mirror M1.

  The light beam reciprocating in the second imaging optical system is deflected by the deflecting / reflecting mirror FM1 in the direction of approximately 45 ° with respect to the deflecting / reflecting mirror FM1, forms a second intermediate image, passes through the refractive member field1, and passes through the deflecting / reflecting mirror FM2. Led to. The light beam deflected by about 45 ° with respect to the deflecting reflecting mirror FM2 by the deflecting reflecting mirror FM2 is guided to the third imaging optical system G3. The refractive member field1 facilitates the introduction of the light emitted from the deflecting mirror FM1 into the deflecting mirror FM2.

  The third imaging optical system G3 includes optical elements L305 to L301 and a concave reflecting mirror M2 along the traveling direction of light from the deflecting reflecting mirror FM2. More specifically, the third imaging optical system G3 includes a positive meniscus lens L305 having a convex surface facing the deflecting reflecting mirror FM2, a positive meniscus lens L304 having a concave surface facing the deflecting reflecting mirror FM2, and a deflecting reflecting mirror. L303 having a convex surface facing FM2 side. The third imaging optical system G3 further includes a meniscus lens L302 having a concave surface facing the deflecting reflector FM2, a negative lens L301, and a concave reflector M2. The light beam reciprocating through the third imaging optical system GM3 forms a third intermediate image. The third intermediate image is formed in the vicinity of the deflecting reflector FM2, thereby facilitating the separation of the light flux. The light beam from the third intermediate image is guided to the fourth imaging optical system G4.

  The fourth imaging optical system G4 includes optical elements L401 to L416 along the traveling direction of light from the third imaging optical system G3. More specifically, the fourth imaging optical system G4 has a convex lens L401, a positive meniscus lens L402 having a concave surface facing the second object 102, and a concave aspheric surface facing the third imaging optical system G3. Negative meniscus lens L403. The fourth imaging optical system G4 includes a negative meniscus lens L404 having an aspheric surface facing the third imaging optical system G3, a concave lens L405 having a concave aspheric surface facing the second object 102, and a second lens And a meniscus lens L406 having a convex surface facing the object 102 side. The fourth imaging optical system G4 includes a negative meniscus lens L407 having a convex aspheric surface directed toward the third imaging optical system, convex lenses L408 and 409, and a positive surface having a concave surface directed toward the second object 102. Meniscus lenses L410, 411, and 412 are further included. The fourth imaging optical system G4 includes a positive meniscus lens L413 having a concave aspheric surface facing the second object 102, and a meniscus lens L414 having a convex aspheric surface facing the third imaging optical system G3. It has further. The fourth imaging optical system G4 further includes a meniscus lens L415 having a concave aspheric surface facing the second object 102, and a planoconvex lens L416 having a flat second object 102 side.

  In this embodiment, the numerical aperture on the image side is NA = 1.45, the reduction magnification is 1/4, and quartz is used for the glass material. The distance between the object images (the first object plane to the second object plane) is L = about 2000 mm. The light beam in the range of about 14.00 mm to 68.00 mm (the third imaging optical system G3 side is negative) of the height of the first object 101 is the second object without interference between the deflecting mirrors FM1 and FM2. An image is formed on 102. A rectangular exposure area of at least 26 mm in the length direction and about 7 mm in width can be secured.

  Tables 6 to 9 show the specifications of the numerical embodiment of Example 2 below.

  A specific configuration of the third embodiment is shown in FIG.

  The first imaging optical system G1 of the refractive optical system includes optical elements L101 to L111 along the light traveling direction from the first object 101 side. More specifically, the first imaging optical system G1 includes a parallel plane plate L101, a positive lens L102 having an aspheric convex surface facing the second object 102, a positive lens L103, and a first object 101. And a meniscus lens L104 having a convex surface on the side. The first imaging optical system G1 further includes a positive meniscus lens L105 having a concave aspheric surface facing the second object 102, and a meniscus lens L106 having a concave aspheric surface facing the first object 101. . The first imaging optical system G1 further includes a meniscus lens L107 having a concave surface facing the first object 101, and a positive meniscus lens L108 having a concave surface facing the first object 101. The first imaging optical system G1 includes a negative meniscus lens L109 having a convex aspheric surface facing the second object 102, a positive meniscus lens L110 having a concave surface facing the first object 101, and a positive lens L111. It has further. The light beam that has passed through the first imaging optical system G1 forms a first intermediate image. The first intermediate image is formed in the vicinity of the deflecting mirror FM1, thereby facilitating the separation of the light flux. The light beam from the first intermediate image is guided to the second imaging optical system G2.

  The second imaging optical system G2 includes optical elements L201 to L205 and a concave reflecting mirror M1 along the traveling direction of the light from the first imaging optical system G1. More specifically, the second imaging optical system G2 has a positive meniscus lens L201 having a convex surface facing the first imaging optical system G1 and a convex aspheric surface facing the first imaging optical system G1. It further has a positive meniscus lens L202 and a concave lens L203. The second imaging optical system G2 includes a negative meniscus lens L204 having a concave surface facing the first imaging optical system G1 and a negative meniscus lens L205 having a concave aspheric surface facing the first imaging optical system G1. And a concave reflecting mirror M1.

  The light beam reciprocating through the second imaging optical system G2 is deflected by the deflecting reflector FM1 in a direction of approximately 45 ° with respect to the deflecting reflector FM1, forms a second intermediate image, passes through the refractive member field1, and passes through the deflecting reflector mirror. Guided to FM2. The light beam deflected by about 45 ° with respect to the deflecting reflecting mirror FM2 by the deflecting reflecting mirror FM2 is guided to the third imaging optical system G3. The refractive member field1 facilitates the introduction of the light emitted from the deflecting mirror FM1 into the deflecting mirror FM2.

  The third imaging optical system G3 includes optical elements L305 to L301 and a concave reflecting mirror M2 along the traveling direction of light from the deflecting reflecting mirror FM2. More specifically, the third imaging optical system G3 includes a positive meniscus lens L305 having a convex surface facing the deflecting reflecting mirror FM2, and a meniscus lens L304 having a convex surface facing the deflecting reflecting mirror FM2. The third imaging optical system G3 includes a positive meniscus lens L303 having a convex surface facing the deflecting reflector FM2, a meniscus lens L302 having a concave surface facing the deflecting reflector FM2, a negative lens L301, and a concave reflecting mirror. And M2.

  The light beam reciprocating through the third imaging optical system G3 forms a third intermediate image. The third intermediate image is formed in the vicinity of the deflecting reflector FM2, thereby facilitating the separation of the light flux. The light beam from the third intermediate image is guided to the fourth imaging optical system G4.

  The fourth imaging optical system G4 includes optical elements L401 to L415 along the traveling direction of light from the third imaging optical system G3. More specifically, the fourth imaging optical system G4 includes convex lenses L401 and L402, and a concave lens L403 with a concave aspheric surface facing the third imaging optical system G3. The fourth imaging optical system G4 includes a negative meniscus lens L404 having a concave aspheric surface facing the third imaging optical system G3, and a meniscus lens L405 having a concave aspheric surface facing the second object 102. It has further. The fourth imaging optical system G4 includes a meniscus lens L406 having a concave surface facing the deflecting reflector FM2, and a negative meniscus lens L407 and a convex lens L408 having a convex aspheric surface facing the third imaging optical system G3. 409. The fourth imaging optical system G4 includes positive meniscus lenses L410, 411, and 412 having a concave surface facing the second object 102, and a positive meniscus lens L413 having a concave aspheric surface facing the second object 102. Also have. The fourth imaging optical system G4 includes a meniscus lens L414 having a convex aspheric surface facing the third imaging optical system, a meniscus lens L415 having a concave aspheric surface facing the second object 102, and a second one. The object 102 side further includes a plano-convex lens L416 having a flat surface.

  In this embodiment, the numerical aperture on the image side is NA = 1.45, the reduction magnification is 1/4, and quartz is used for the glass material. The distance between the object images (the first object plane to the second object plane) is L = about 2000 mm. The luminous flux in the range of about -14.00 mm to −68.00 mm (the third imaging optical system side is negative) of the height of the first object 101 is the second without interference between the deflecting reflecting mirrors FM1 and FM2. An image is formed on the object 102. A rectangular exposure area of at least 26 mm in the length direction and about 7 mm in width can be secured.

  Tables 10 to 13 show the specifications of the numerical embodiment of Example 3.

  An exposure apparatus 1 to which the projection optical system shown in FIGS. 1 to 5 is applied will be described below with reference to FIG. Here, FIG. 6 is a schematic block diagram of the exposure apparatus 1. As shown in FIG. 6, the exposure apparatus 1 includes an illumination apparatus 110, a mask or reticle 130, a reticle stage 132, a projection optical system 140, a main control unit 150, a monitor and input device 152, and a wafer 170. Wafer stage 176 and liquid 180 as a medium. As described above, the exposure apparatus 1 partially or entirely immerses the final surface on the wafer 170 side of the projection optical system 140 in the liquid 180, and applies the pattern formed on the mask MS through the liquid 180 to the wafer W. It is an immersion type exposure apparatus that exposes the light. Although the exposure apparatus 1 of the present embodiment is a step-and-scan projection exposure apparatus, the present invention can apply a step-and-repeat system and other exposure systems.

  The illumination device 100 illuminates a reticle 130 on which a transfer circuit pattern is formed, and includes a light source unit and an illumination optical system.

  The light source unit includes a laser 112 as a light source and a beam shaping system 114. The laser 112 can use light from a pulse laser such as an ArF excimer laser having a wavelength of about 193 nm, a KrF excimer laser having a wavelength of about 248 nm, or an F2 excimer laser having a wavelength of about 157 nm. The type and number of lasers are not limited, and the type of light source unit is not limited.

  For example, a beam expander including a plurality of cylindrical lenses can be used as the beam shaping system 114, and the aspect ratio of the dimension of the cross-sectional shape of the parallel light from the laser 112 is converted into a desired value (for example, the cross-section The beam shape is formed into a desired one by changing the shape from a rectangle to a square. The beam shaping system 114 forms a light beam having a size and a divergence angle necessary for illuminating an optical integrator 118 described later.

  The illumination optical system is an optical system that illuminates the reticle 130. In the present embodiment, the condensing optical system 116, the polarization control means 117, the optical integrator 118, the aperture stop 120, the condensing lens 122, and the bending lens. A mirror 124, a masking blade 126, and an imaging lens 128 are included. The illumination optical system can also realize various illumination modes such as conventional illumination, annular illumination, and quadrupole illumination.

  The condensing optical system 116 is composed of a plurality of optical elements, and efficiently introduces the optical integrator 118 in a desired shape. For example, the collection optics 116 includes a zoom lens system and controls the distribution of the shape and angle of the incident beam to the optical integrator 118.

  The condensing optical system 116 includes an exposure amount adjustment unit that can change the exposure amount of the illumination light to the reticle 130 for each illumination. The exposure adjustment unit is controlled by the main control unit 150. It is also possible to place an exposure monitor, for example, between the optical integrator 118 and the reticle 130 or at another location and measure the exposure and feed back the result.

  The polarization control unit 117 includes, for example, a polarization element and is disposed at a position substantially conjugate with the pupil 142 of the projection optical system 140. The polarization control means 117 controls the polarization state of a predetermined area of the effective light source formed on the pupil 142, as will be described later. A polarization control means 117 composed of a plurality of types of polarization elements may be provided on a turret that can be rotated by an actuator (not shown), and the main control unit 150 may control driving of the actuator.

  The optical integrator 118 makes the illumination light illuminated on the reticle 130 uniform. In this embodiment, the optical integrator 118 is configured as a fly-eye lens that converts the angle distribution of incident light into a position distribution and emits it. The fly-eye lens is configured by combining a large number of rod lenses (that is, microlens elements) with its entrance and exit surfaces maintained in a Fourier transform relationship. However, the optical integrator 118 in which the present invention can be used is not limited to the fly-eye lens, but includes an optical rod, a diffraction grating, and a plurality of sets of cylindrical lens array plates arranged so that each set is orthogonal.

Immediately after the exit surface of the optical integrator 118, an aperture stop 120 having a fixed shape and diameter is provided. As will be described later, the aperture stop 120 is disposed at a position almost conjugate with the effective light source formed on the pupil 142 of the projection optical system 140, and the aperture shape of the aperture stop 120 is effective on the pupil plane 142 of the projection optical system 140. Corresponds to the light source shape. The aperture stop 120 controls the shape of the effective light source, as will be described later.
The aperture stop 120 can be switched by an aperture replacement mechanism (actuator) 121 so that various aperture stops (to be described later) are positioned in the optical path according to the illumination conditions. Driving of the actuator 121 is controlled by a drive control unit 151 controlled by the main control unit 150. The aperture stop 120 may be configured integrally with the polarization control unit.

  The condensing lens 122 is emitted from a secondary light source in the vicinity of the exit surface of the optical integrator 118, condenses a plurality of light beams that have passed through the aperture stop 120, and is reflected by a mirror 124 to form a masking blade 126 surface as an illuminated slope. Illuminate uniformly with Koehler illumination.

  The masking blade 126 is composed of a plurality of movable light shielding plates, and has an approximately rectangular arbitrary opening shape corresponding to the effective area of the projection optical system 140. The light beam transmitted through the opening of the masking blade 126 is used as illumination light for the reticle 130. The masking blade 126 is an aperture whose opening width is automatically variable, and can change the transfer area. In addition, the exposure apparatus 1 may further include a scan blade having a structure similar to the above-described masking blade that enables the transfer region in the scan direction to be changed. The scanning blade is also a stop whose opening width can be automatically changed, and is provided at a position optically conjugate with the mask 12 surface. The exposure apparatus 1 can set the size of the transfer region in accordance with the size of the shot to be exposed by using these two variable blades.

  The imaging lens 128 irradiates and transfers the opening shape of the masking blade 126 onto the surface of the reticle 130, and reduces and projects the pattern on the surface of the reticle 130 onto the surface of the wafer 170 placed on a wafer chuck (not shown).

  The reticle 130 is obtained by embodying the first object 101 shown in FIGS. 1 to 5. The reticle 130 has a pattern to be transferred thereon, and is supported and driven by the mask stage 132. Diffracted light emitted from the reticle 130 passes through the projection optical system 140 and is projected onto the wafer 170. The wafer 170 is an object to be exposed, and a resist 172 is applied on the substrate 174. The reticle 130 and the wafer 170 are arranged in an optically conjugate relationship. Since the exposure apparatus 1 is a step-and-scan exposure apparatus (that is, a scanner), the pattern of the reticle 130 is transferred onto the wafer 170 by scanning the reticle 130 and the wafer 170. In the case of a step-and-repeat type exposure apparatus (ie, “stepper”), exposure is performed with the reticle 130 and the wafer 170 being stationary.

  The mask stage 132 supports the reticle 130 and is connected to a moving mechanism (not shown). The mask stage 132 and the projection optical system 140 are provided, for example, on a stage barrel surface plate that is supported by a base frame placed on a floor or the like via a damper or the like. Any configuration known in the art can be applied to the mask stage 132. A moving mechanism (not shown) is configured by a linear motor or the like, and can move the reticle 130 by driving the mask stage 132 in the XY directions. The exposure apparatus 1 scans the mask 200 and the wafer 170 in a synchronized state by the main control unit 150.

  The projection optical system 140 is a specific implementation of the projection optical system shown in FIGS. The projection optical system 140 has a function of forming an image of the diffracted light that has passed through the pattern formed on the reticle 130 on the wafer 170.

  The main control unit 150 performs drive control of each unit, and in particular, controls lighting based on information input from the input device of the monitor and input device 152, information from the lighting device 100, and a program stored in a memory (not shown). I do. More specifically, the main control unit 150 controls the shape and polarization state of an effective light source formed on the pupil 142 of the projection optical system 140. For example, in order to achieve the high-resolution imaging performance expected with high NA, it is necessary to cut the light in the P-polarized polarization state that lowers the imaging contrast and image only the S-polarized light. Since it is good, it image-forms using S polarized light which has a polarization direction in the longitudinal direction of a mask pattern. Control information by the main control unit 150 and other information are displayed on the monitor of the monitor and input device 152.

  The wafer 170 is obtained by embodying the second object 102 shown in FIGS. 1 to 5. In another embodiment, the wafer 170 is replaced with a liquid crystal substrate or other object to be exposed. In the wafer 170, a photoresist 172 is applied on the substrate 174.

  Wafer 170 is supported by wafer stage 176. Since any configuration known in the art can be applied to the stage 176, a detailed description of the structure and operation is omitted here. For example, the stage 176 moves the wafer 170 in the XY directions using a linear motor. The reticle 130 and the wafer 170 are scanned synchronously, for example, and the positions of the mask stage 132 and the wafer stage 176 are monitored by a laser interferometer, for example, and both are driven at a constant speed ratio. The stage 176 is provided on a stage surface plate supported on a floor or the like via a damper, for example, and the mask stage 132 and the projection optical system 140 are mounted on the floor surface or the like, for example. It is provided on a lens barrel surface plate (not shown) supported on the base frame via a damper or the like.

  The liquid 180 is immersed in the final surface of the projection optical system 140 on the wafer 170, and a substance that has good transmittance at the exposure wavelength, does not attach dirt to the projection optical system, and has good matching with the resist process is selected. . The final surface of the projection optical system 140 is coated to protect the influence from the liquid 180.

  In exposure, the light beam emitted from the laser 112 is incident on the illumination optical system after its beam shape is shaped into a desired shape by the beam shaping system 114. The condensing optical system 116 efficiently introduces the light beam into the optical integrator 118. At that time, the exposure amount adjusting unit adjusts the exposure amount of the illumination light. The main control unit 150 recognizes the user by inputting the mask pattern information via the monitor and the input device of the input device 152 or by reading the barcode formed on the mask and the like, and is suitable for the mask pattern. The aperture shape and polarization state as illumination conditions are selected by driving an actuator (not shown) of the polarization controller 117 and an actuator 121 of the aperture stop 120.

  The optical integrator 118 makes the illumination light uniform, and the aperture stop 120 sets a desired effective light source shape. Such illumination light illuminates the mask 200 under optimum illumination conditions via the condenser lens 122, the bending mirror 124, the masking blade 126, and the imaging lens 128.

  The light beam that has passed through the reticle 130 is reduced and projected onto the wafer 170 at a predetermined magnification by the projection optical system 140. In the case of a step-and-scan exposure apparatus, the light source 112 and the projection optical system 140 are fixed, and the reticle 130 and the wafer 170 are synchronously scanned to expose the entire shot. Further, the wafer stage 176 is stepped to move to the next shot, and a new scanning operation is performed. This scan and step are repeated to expose and transfer a large number of shots onto the wafer 170. If the exposure apparatus adopts a step-and-repeat method, exposure is performed with the reticle 130 and the wafer 170 being stationary.

  Since the final surface of the projection optical system 140 on the wafer 170 is immersed in the liquid 180 having a refractive index higher than that of air, the NA of the projection optical system 140 becomes high, and the resolution formed on the wafer 170 becomes fine. In addition, since the reticle surface and the wafer surface can be directed in the direction of gravity, it is possible to prevent the aberration due to the self-weight deformation of the reticle 130 from adversely affecting the liquid 180 on the wafer 170 from being spilled. In addition, the pair of concave reflecting mirrors M1 and M2 can correct the aberration of the projection optical system, and the concave reflecting mirrors M1 and M2 can be directed in the direction of gravity, so that the aberration due to the self-weight deformation has an adverse effect. Can be prevented. Further, a high contrast image is formed on the resist 172 by polarization control. Thereby, the exposure apparatus 1 can provide a high-quality device (semiconductor element, LCD element, imaging element (CCD, etc.), thin film magnetic head, etc.) by performing pattern transfer onto the resist with high accuracy.

  Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described with reference to FIGS. FIG. 7 is a flowchart for explaining how to fabricate devices (ie, semiconductor chips such as IC and LSI, LCDs, CCDs, etc.). Here, the manufacture of a semiconductor chip will be described as an example. In step 1 (circuit design), a device circuit is designed. In step 2 (mask production), a mask on which the designed circuit pattern is formed is produced. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique of the present invention using the mask and the wafer. Step 5 (assembly) is called a post-process, and is a process for forming a semiconductor chip using the wafer created in step 4. The assembly process (dicing, bonding), packaging process (chip encapsulation), and the like are performed. Including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device created in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

  FIG. 8 is a detailed flowchart of the wafer process in Step 4. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), an electrode is formed on the wafer by vapor deposition or the like. Step 14 (ion implantation) implants ions into the wafer. In step 15 (resist process), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the exposure apparatus 1 to expose a circuit pattern on the mask onto the wafer. In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeatedly performing these steps, multiple circuit patterns are formed on the wafer. According to the device manufacturing method of the present invention, it is possible to manufacture a higher quality device than before. As described above, the device manufacturing method using the lithography technique of the present invention and the resulting device also constitute one aspect of the present invention. The present invention also covers the device itself that is an intermediate and final product of the device manufacturing method. Such devices include, for example, semiconductor chips such as LSI and VLSI, CCDs, LCDs, magnetic sensors, thin film magnetic heads, and the like.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary. For example, in FIG. 5, a projection optical system that does not include Field 1 is also within the scope of the present invention.

It is a schematic block diagram of the projection optical system of one Example of this invention. It is a schematic block diagram of the modification of the projection optical system shown in FIG. It is a specific block diagram of the projection optical system shown in FIG. It is a specific block diagram of the modification of the projection optical system shown in FIG. It is a specific block diagram of the projection optical system shown in FIG. It is a schematic block diagram of the exposure apparatus as another side surface of this invention. It is a flowchart for demonstrating manufacture of devices (semiconductor chips, such as IC and LSI, LCD, CCD, etc.). 8 is a detailed flowchart of the wafer process in Step 4 shown in FIG. 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 101 1st object 102 2nd object G1-G4 Imaging optical system 130 Reticle 140 Projection optical system 170 Wafer 180 Liquid

Claims (15)

A catadioptric projection optical system for forming an image of a first object on a second object,
A first imaging optical system for forming a first intermediate image of the first object;
A second imaging optical system for forming a second intermediate image of the first object based on a light beam from the first intermediate image;
A third imaging optical system for forming a third intermediate image of the first object based on a light beam from the second intermediate image;
A fourth imaging optical system for forming an image of the first object on the second object based on a light beam from the third intermediate image;
A catadioptric projection optical system comprising: two deflecting reflecting mirrors provided between the second and third imaging optical systems. One of the first to fourth imaging optical systems has a partial optical system made of only a refractive member,
2. The catadioptric projection according to claim 1, wherein another one of the first to fourth imaging optical systems includes a partial optical system having an imaging function including a concave reflecting mirror. Optical system. The first to fourth imaging optical systems are
2. The catadioptric projection optical system according to claim 1, wherein the catadioptric projection optical system has two pairs of a partial optical system composed of only a refractive member and a partial optical system having an imaging function including a concave reflecting mirror. The first and fourth imaging optical systems are partial optical systems composed only of refractive members,
2. The catadioptric projection optical system according to claim 1, wherein the second and third imaging optical systems are partial optical systems including a concave reflecting mirror.   5. The catadioptric projection optical system according to claim 1, further comprising a refractive member between the second and third imaging optical systems.   6. The catadioptric projection optical system according to claim 4, wherein the concave reflecting mirror is not arranged coaxially.   6. The reflection according to claim 4, wherein one of the concave reflecting mirrors is configured to be substantially parallel to the first object, and the other of the concave reflecting mirrors is disposed to be substantially parallel to the second object. Refractive projection optical system. When the imaging magnification of the third imaging optical system is β ₃ , the imaging magnification of the fourth imaging optical system is β ₄ , and the numerical aperture of the entire system is NA,
The catadioptric projection optical system according to claim 1, wherein the following condition is satisfied. Of the two deflecting reflectors, the one closer to the first object along the optical path is the first deflecting reflector, and the distance from the first deflecting reflector of the focal point in the second intermediate image is A, When the interval between the two deflecting mirrors is B,
The catadioptric projection optical system according to claim 1, wherein the following condition is satisfied. When the angle between the optical axis and the principal ray of the outermost field angle between the two deflecting reflectors is tel,
The catadioptric projection optical system according to claim 1, wherein the following condition is satisfied. A catadioptric projection optical system, which is an imaging system that forms an intermediate image of a first object a plurality of times and forms an image on a second object,
The first and second object planes are arranged in parallel on opposite sides;
The catadioptric projection optical system has two concave reflecting mirrors;
One of the two concave reflecting mirrors is disposed to face one of the first and second object surfaces, and the other of the two concave reflecting mirrors faces the other of the first and second object surfaces. A catadioptric projection optical system, wherein   12. The catadioptric projection optical system according to claim 11, further comprising two deflecting reflecting mirrors, wherein an optical path from the first object toward the second object is substantially H-shaped. An illumination optical system that illuminates a pattern with light from a light source;
An exposure apparatus comprising: the catadioptric projection optical system according to claim 1 that projects an image of the pattern onto an object to be processed.   14. The exposure apparatus according to claim 13, wherein at least part of the space between the object to be processed and the lens surface closest to the object to be processed of the catadioptric projection optical system is filled with liquid. Exposing the object to be exposed using the exposure apparatus according to claim 13 or 14,
And developing the exposed object to be exposed.