JP2007132981A - Objective optical system, aberration measuring instrument and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an objective optical system which has a numerical aperture larger than 1 and whose aberration is satisfactorily corrected. <P>SOLUTION: The objective optical system is equipped with: a first optical member (31a) having nearly plane parallel form; a second optical member (31ba) turning its convex surface to an emitting side and having positive refractive power; a positive lens group (31bb); and a negative lens group (31bc) in order from an object side. An optical path between the first optical member and the second optical member is filled with a medium (Lm3) having a refractive index larger than the maximum numerical aperture on the incident side of the objective optical system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an objective optical system, an aberration measuring apparatus, and an exposure apparatus, and more particularly to an objective optical system suitable for an apparatus for measuring wavefront aberration of a projection optical system mounted on the exposure apparatus.

  In a photolithography process for manufacturing semiconductor elements, etc., a mask (or reticle) pattern image is projected and exposed on a photosensitive substrate (a wafer coated with a photoresist, a glass plate, etc.) via a projection optical system. An exposure apparatus is used. In the exposure apparatus, as the degree of integration of semiconductor elements and the like is improved, the resolving power (resolution) required for the projection optical system is increasing. In order to satisfy the requirement for the resolution of the projection optical system, it is necessary to shorten the wavelength λ of the illumination light (exposure light) and increase the image-side numerical aperture NA of the projection optical system. Specifically, the resolution of the projection optical system is represented by k · λ / NA (k is a process coefficient).

  The image-side numerical aperture NA is n, where n is the refractive index of the medium (usually a gas such as air) between the projection optical system and the photosensitive substrate, and θ is the maximum incident angle on the photosensitive substrate.・ It is expressed by sinθ. In this case, if the maximum incident angle θ is increased to increase the image-side numerical aperture, the incident angle to the photosensitive substrate and the exit angle from the projection optical system increase, and the reflection loss on the optical surface increases. Thus, a large effective image-side numerical aperture cannot be ensured. Therefore, an immersion technique is known in which an image-side numerical aperture is increased by filling a medium such as a liquid having a high refractive index in the optical path between the projection optical system and the photosensitive substrate.

  In addition, the projection optical system mounted in the exposure apparatus is required to have extremely small residual aberration in order to achieve high resolution. Therefore, when manufacturing the exposure apparatus, the wavefront aberration of the projection optical system is measured using a predetermined aberration measuring apparatus (wavefront measuring apparatus), and the projection optical system is optically adjusted based on the measurement result. In this case, in the objective optical system used in this type of aberration measuring apparatus, a plane parallel plate in which a pattern such as a pinhole or an alignment mark is formed on the object side surface on the most object side (projection optical system side). In many cases, a pinhole member made of is arranged (see, for example, Patent Document 1).

JP 2002-169083 A

  In an immersion type exposure apparatus, an image-side numerical aperture greater than 1 can be secured by filling the optical path between the projection optical system and the photosensitive substrate with a liquid. However, in a conventional objective optical system for an aberration measurement apparatus, light incident on the object side (incident side) surface of the pinhole member at a large incident angle corresponding to a numerical aperture greater than 1 Is totally reflected by the plane on the exit side of the lens, and does not contribute to aberration measurement. As a result, the conventional aberration measuring apparatus has a disadvantage that the wavefront aberration of the immersion type projection optical system (imaging optical system) having an image-side numerical aperture larger than 1 cannot be measured with a required accuracy. It was.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an objective optical system that has a numerical aperture greater than 1 and has good aberration correction. It is another object of the present invention to provide an aberration measuring apparatus capable of measuring the wavefront aberration of an imaging optical system with high accuracy by using an objective optical system having a numerical aperture greater than 1 and having an aberration corrected satisfactorily. Objective. Also provided is an exposure apparatus capable of performing high-accuracy and good projection exposure through a projection optical system optically adjusted with high accuracy using an aberration measuring apparatus capable of measuring wavefront aberration with high precision. For the purpose.

  In order to solve the above-described problem, in the first embodiment of the present invention, in order from the object side, a first optical member having a substantially parallel flat shape and a second optical member having a positive refractive power with a convex surface facing the exit side. An objective optical system including an optical member, wherein an optical path between the first optical member and the second optical member is a medium having a refractive index larger than a maximum numerical aperture on the incident side of the objective optical system. An objective optical system characterized by being satisfied is provided. The substantially parallel flat shape includes that one or both light transmission surfaces of the first optical member have a slight curvature.

  According to a second aspect of the present invention, there is provided an aberration measuring apparatus for measuring the wavefront aberration of an imaging optical system, comprising the objective optical system of the first aspect.

  According to a third aspect of the present invention, there is provided an aberration measuring apparatus according to the second aspect for measuring a wavefront aberration of the projection optical system in an exposure apparatus that exposes a predetermined pattern onto a photosensitive substrate via the projection optical system. An exposure apparatus is provided.

  In the objective optical system according to the typical aspect of the present invention, the optical path between the first optical member having a parallel plane shape and the second optical member having a positive refractive power with the convex surface facing the exit side is an objective optical system. The optical system is filled with a medium having a refractive index larger than the maximum numerical aperture on the incident side of the optical system. With this configuration, the light beam incident on the first optical member at the maximum incident angle corresponding to the incident-side maximum numerical aperture greater than 1 is also totally reflected at the boundary surface between the plane on the exit side of the first optical member and the medium. It is possible to contribute to aberration measurement without any problem, and to suppress the occurrence of aberration when exiting from the first optical member and incident on the second optical member. In addition, by appropriately setting the radius of curvature of the exit-side convex surface of the second optical member, it is possible to suppress the occurrence of aberrations in the entire optical system.

  That is, according to the present invention, it is possible to realize an objective optical system having a numerical aperture larger than 1 and having excellent aberration correction. As a result, in the present invention, an aberration measuring apparatus capable of measuring the wavefront aberration of the imaging optical system with high accuracy by using an objective optical system having a numerical aperture greater than 1 and aberrations corrected favorably. Can be realized. In the exposure apparatus of the present invention, high-accuracy and good projection exposure can be performed via a projection optical system optically adjusted with high accuracy using an aberration measuring apparatus capable of measuring wavefront aberration with high accuracy. As a result, a good device can be manufactured with high accuracy.

  As described above, in a conventional objective optical system for an aberration measuring apparatus, light incident on the pinhole member at an incident angle corresponding to a numerical aperture larger than 1 is totally reflected on the plane on the exit side of the pinhole member. The Total reflection on the exit side surface of the pinhole member can be avoided by forming the exit side surface of the pinhole member into a curved surface. However, as in the case of the first lens closest to the object side of the microscope objective lens having a high magnification and a high aperture ratio, when a small radius of curvature that substantially satisfies the aplanatic condition is applied to the exit side surface of the pinhole member, Since the outer diameter of the pinhole member becomes too small, a necessary alignment mark or the like cannot be provided on the object-side surface of the pinhole member.

  On the other hand, if the radius of curvature to be applied to the exit surface of the pinhole member is set relatively large in order to ensure a relatively large outer diameter of the pinhole member, the deviation from the aplanatic condition becomes large, and the amount of aberration generated is reduced. Easy to grow. In this case, since the incident angle of the pinhole member to the subsequent lens group is naturally increased, the aberration (decentration aberration) caused by the decentering of the lens component from the optical axis is likely to increase.

  In the objective optical system of the present invention, the optical path between the first optical member (pinhole member) having a parallel plane shape and the positive lens (second optical member) having a convex surface on the exit side is used as the objective optical system. It is filled with a liquid-like medium having a refractive index greater than the maximum numerical aperture on the incident side of the system. With this configuration, a light beam incident on the first optical member at a maximum incident angle corresponding to an incident-side maximum numerical aperture greater than 1 is also totally reflected at the boundary surface between the emission-side plane of the first optical member and the medium. It contributes to aberration measurement without being done.

  In addition, with the above-described configuration, it is possible to suppress the occurrence of aberration when exiting from the first optical member, and it is also possible to suppress the occurrence of aberration when incident on the second optical member. Since the positive lens as the second optical member has a convex surface facing the exit side, for example, by setting the radius of curvature of the convex surface on the exit side of the positive lens so as to substantially satisfy the aplanatic condition, the aberration of the entire optical system can be reduced. It is possible to convert a divergent light beam incident on the optical system into a convergent light beam while suppressing generation. Thus, according to the present invention, it is possible to realize an objective optical system having a numerical aperture larger than 1 and having excellent aberration correction.

  In the present invention, since the first optical member has a substantially parallel flat shape, the outer diameter of the first optical member can be set without being limited by the edge thickness of the first optical member. There is also an advantage that the degree of freedom in arranging a pattern such as a required alignment mark on the object side (incident side) surface of one optical member is improved. Further, in the present invention, an objective optical system with better aberration correction is realized by arranging a positive lens group on the exit side of the second optical member and arranging a negative lens group on the exit side of the positive lens group. can do.

  Further, when the objective optical system of the present invention is applied to an aberration measuring apparatus that measures the aberration of the immersion type projection optical system, the image plane of the projection optical system and the object plane of the objective optical system are matched, and The object-side surface of the first optical member on which patterns such as alignment marks and pinholes are formed coincides with the object surface of the objective optical system.

  Further, when the objective optical system of the present invention is applied to an aberration measuring apparatus that measures the aberration of a liquid immersion type projection optical system, a medium (immersion liquid) interposed between the projection optical system and the photosensitive substrate, that is, The medium in contact with the object side surface of the first optical member and the medium satisfying the optical path between the first optical member and the second optical member in the objective optical system are preferably the same type. In this case, there is no need to separately configure the apparatus for supplying a medium between the projection optical system and the photosensitive substrate and the apparatus for supplying a medium between the first optical member and the second optical member. Since a part of the apparatus including the medium supply source can be made common, it is advantageous in configuration.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, the X axis and the Y axis are set in a direction parallel to the wafer W, and the Z axis is set in a direction orthogonal to the wafer W. More specifically, the XY plane is set parallel to the horizontal plane, and the + Z axis is set upward along the vertical direction.

  As shown in FIG. 1, the exposure apparatus of this embodiment includes, for example, an ArF excimer laser light source that is an exposure light source, and includes an illumination optical system 1 that includes an optical integrator (homogenizer), a field stop, a condenser lens, and the like. ing. Exposure light (exposure beam) IL composed of ultraviolet pulsed light having a wavelength of 193 nm emitted from the light source passes through the illumination optical system 1 and illuminates the reticle (mask) R.

  A pattern to be transferred is formed on the reticle R, and a rectangular (slit-like) pattern region having a long side along the X direction and a short side along the Y direction is illuminated in the entire pattern region. Is done. The light that has passed through the reticle R forms a reticle pattern at a predetermined reduction projection magnification in an exposure area on a wafer (photosensitive substrate) W coated with a photoresist via an immersion type projection optical system PL.

  That is, a rectangular still exposure having a long side along the X direction and a short side along the Y direction on the wafer W so as to optically correspond to the rectangular illumination region on the reticle R. A pattern image is formed in the area (effective exposure area). The reticle R is held parallel to the XY plane on the reticle stage RST, and a mechanism for finely moving the reticle R in the X direction, the Y direction, and the rotation direction is incorporated in the reticle stage RST. In reticle stage RST, positions in the X direction, Y direction, and rotational direction are measured and controlled in real time by a reticle laser interferometer (not shown).

  The wafer W is fixed parallel to the XY plane on the Z stage 9 via a wafer holder (not shown). The Z stage 9 is fixed on an XY stage 10 that moves along an XY plane substantially parallel to the image plane of the projection optical system PL, and the focus position (Z direction position) and tilt angle of the wafer W are set. Control. The Z stage 9 is measured and controlled in real time by the wafer laser interferometer 13 using the moving mirror 12 provided on the Z stage 9 in the X direction, the Y direction, and the rotational direction.

  The XY stage 10 is placed on the base 11 and controls the X direction, Y direction, and rotation direction of the wafer W. On the other hand, the main control system 14 provided in the exposure apparatus of the present embodiment adjusts the position of the reticle R in the X direction, the Y direction, and the rotational direction based on the measurement values measured by the reticle laser interferometer. That is, the main control system 14 adjusts the position of the reticle R by transmitting a control signal to a mechanism incorporated in the reticle stage RST and finely moving the reticle stage RST.

  The main control system 14 adjusts the focus position (position in the Z direction) and the tilt angle of the wafer W in order to adjust the surface on the wafer W to the image plane of the projection optical system PL by the auto focus method and the auto leveling method. I do. That is, the main control system 14 transmits a control signal to the wafer stage drive system 15 and drives the Z stage 9 by the wafer stage drive system 15 to adjust the focus position and tilt angle of the wafer W.

  Further, the main control system 14 adjusts the position of the wafer W in the X direction, the Y direction, and the rotation direction based on the measurement values measured by the wafer laser interferometer 13. That is, the main control system 14 transmits a control signal to the wafer stage drive system 15 and drives the XY stage 10 by the wafer stage drive system 15 to adjust the position of the wafer W in the X direction, the Y direction, and the rotation direction. .

  At the time of exposure, the main control system 14 transmits a control signal to a mechanism incorporated in the reticle stage RST and also transmits a control signal to the wafer stage drive system 15, and a speed ratio corresponding to the projection magnification of the projection optical system PL. Then, the reticle stage RST and the XY stage 10 are driven to project and expose the pattern image of the reticle R into a predetermined shot area on the wafer W. Thereafter, the main control system 14 transmits a control signal to the wafer stage drive system 15, and drives the XY stage 10 by the wafer stage drive system 15, thereby step-moving another shot area on the wafer W to the exposure position.

  In this way, the operation of scanning and exposing the pattern image of the reticle R on the wafer W by the step-and-scan method is repeated. That is, in the present embodiment, the position of the reticle R and the wafer W is controlled using the wafer stage drive system 15 and the wafer laser interferometer 13, and the short side direction of the rectangular stationary exposure region and the stationary illumination region, that is, the Y direction. Are moved along the reticle stage RST and the XY stage 10 along with the reticle R and the wafer W in synchronization (scanning), thereby having a width equal to the long side of the static exposure region on the wafer W and A reticle pattern is scanned and exposed to an area having a length corresponding to the scanning amount (movement amount) of the wafer W.

  FIG. 2 is a diagram schematically showing a configuration between the boundary lens and the wafer in the present embodiment. Referring to FIG. 2, in the projection optical system PL according to the present embodiment, the reticle R side (object side) surface is in contact with the second liquid (generally medium) Lm2, and the wafer W side (image side) surface is the first. A plane parallel plate Lp that is in contact with one liquid (generally a medium) Lm1 is arranged on the most wafer side. A boundary lens Lb is disposed adjacent to the plane parallel plate Lp, with the reticle R side contacting the gas and the wafer W side contacting the second liquid Lm2.

In the present embodiment, pure water (deionized water) that can be easily obtained in large quantities at a semiconductor manufacturing factory or the like is used as the first liquid Lm1 and the second liquid Lm2. Also, as the first liquid Lm1 and the second liquid Lm2, for example, water containing H ⁺ , Cs ⁺ , K ⁺ , Cl ⁻ , SO ₄ ²⁻ , PO ₄ ²⁻ , isopropanol, glycerol, hexane, heptane, decane, etc. Can be used.

  In a step-and-scan type exposure apparatus that performs scanning exposure while moving the wafer W relative to the projection optical system PL, between the boundary lens Lb of the projection optical system PL and the wafer W from the start to the end of the scanning exposure. For example, the technique disclosed in International Publication No. WO99 / 49504, the technique disclosed in Japanese Patent Application Laid-Open No. 10-303114, or the like can be used to keep the liquid (Lm1, Lm2) filled in the optical path. .

  In the present embodiment, as shown in FIG. 1, the first liquid Lm1 is circulated in the optical path between the plane parallel plate Lp and the wafer W using the first water supply / drainage mechanism 21. Further, the second liquid Lm2 is circulated in the optical path between the boundary lens Lb and the plane parallel plate Lp using the second water supply / drainage mechanism 22. In this way, by circulating the liquid as the immersion liquid at a minute flow rate, it is possible to prevent the liquid from being altered by the effects of antiseptic and mildewproofing.

  The exposure apparatus of the present embodiment includes an aberration measuring device 30 (not shown in FIG. 1) for measuring the wavefront aberration of the projection optical system PL as an imaging optical system. Referring to FIG. 3, in the aberration measuring apparatus 30 of the present embodiment, when measuring the wavefront aberration of the immersion type projection optical system PL that is the optical system to be tested, the aberration is measured on the reticle stage RST (not shown in FIG. 3). Test mask TM is installed. In the test mask TM, a plurality of circular openings TMa for measuring aberration are two-dimensionally formed (for example, in a matrix along the X and Y directions).

  In addition, the aberration measuring apparatus 30 of the present embodiment has a pinhole member that is mounted on the wafer stage (9, 10; not shown in FIG. 3) at substantially the same height position (Z-direction position) as the exposure surface of the wafer W. An objective optical system 31 composed of 31a and a subsequent lens group 31b is provided. That is, the object side (projection optical system PL side) optical surface of the pinhole member 31a is positioned on the image plane of the projection optical system PL, and a pinhole 31aa is formed at the center of the optical surface. An alignment mark (not shown) for aligning the pinhole member 31a with the projection optical system PL is formed around the pinhole 31aa on the object-side optical surface of the pinhole member 31a.

  The pinhole 31aa is set larger than the image of the opening TMa of the test mask TM formed through the projection optical system PL. In the aberration measuring apparatus 30, the light passing through one opening TMa of the test mask TM, the projection optical system PL, and the pinhole 31aa of the pinhole member 31a passes through the objective optical system 31 and the afocal relay lens system (not shown). Then, the light enters the micro fly's eye lens (micro lens array) 32.

  The micro fly's eye lens 32 is arranged so that its incident surface is located at or near the position of the exit pupil of the objective optical system 31. The micro fly's eye lens 32 is an optical element configured by, for example, a large number of microlenses 32a having a square cross section and having positive refractive power arranged vertically and horizontally. The micro fly's eye lens 32 is configured, for example, by performing etching processing on a plane parallel glass plate to form a micro lens group, and functions as a wavefront dividing element.

  Therefore, the light beam incident on the micro fly's eye lens 32 is two-dimensionally divided by a large number of microlenses 32a, and an image of one opening TMa is formed in the vicinity of the rear focal plane of each microlens 32a. The In other words, many images of the opening TMa are formed in the vicinity of the rear focal plane of the micro fly's eye lens 32. The images of the many openings TMa formed in this way are detected by the CCD 33 as a two-dimensional image sensor. The output of the CCD 33 is supplied to the signal processing unit 34.

  In the aberration measuring apparatus 30 of the present embodiment, the wavefront aberration of the projection optical system PL related to the position of the pinhole 31aa is measured based on the information related to the images of the many openings TMa supplied from the CCD 33 to the signal processing unit 34. Can do. Note that the detailed configuration and operation of the aberration measuring apparatus 30 excluding the objective optical system 31 can be referred to, for example, Japanese Patent Application Laid-Open No. 2002-169083. Hereinafter, the configuration and operation of the objective optical system 31 according to the present embodiment will be described.

  In each example of the present embodiment, the objective optical system includes, in order from the object side, a pinhole member (first optical member) 31a having the form of a plane-parallel plate, and a positive lens (second lens) having a convex surface on the exit side. Optical member) 31ba, a positive lens group 31bb having a positive refractive power as a whole, and a negative lens group 31bc having a negative refractive power as a whole. In each embodiment, the object-side surface of the pinhole member 31a on which a pattern such as the pinhole 31aa is formed coincides with the object surface of the objective optical system 31, and the image plane of the projection optical system PL and the objective optical system 31 object planes coincide with each other.

[First embodiment]
FIG. 4 is a diagram schematically showing a lens configuration of the objective optical system according to the first example of the present embodiment. Referring to FIG. 4, in the objective optical system of the first example, the positive lens 31ba is configured as a plano-convex lens having a convex surface having a strong curvature on the exit side. The positive lens group 31bb includes, in order from the object side, a positive meniscus lens L11 having a concave surface facing the object side, a positive meniscus lens L12 having a concave surface facing the object side, a negative meniscus lens L13 having a convex surface facing the object side, The lens includes a biconvex lens L14 and a biconvex lens L15. The negative lens group 31bc is composed of a biconcave lens L21.

  In the first embodiment, an ArF excimer laser beam (wavelength λ = 193 nm), which is used light (exposure light), is used between the pinhole member (first optical member) 31a and the positive lens (second optical member) 31ba. ) With pure water Lm3 having a refractive index of 1.436. In the first embodiment, all optical members (parallel plane plates and lenses) constituting the objective optical system are made of quartz having a refractive index of 1.5603 with respect to the wavelength λ = 193 nm of the used light. Yes.

  The following table (1) lists the values of the specifications of the objective optical system according to the first example. In the main specifications of Table (1), NA represents the incident-side numerical aperture (incident-side maximum numerical aperture) of the objective optical system. In the optical member specifications of Table (1), the surface number is the order of each surface from the object side, r is the radius of curvature (mm) of each surface, d is the spacing (mm) between the surfaces, n Represents the refractive index with respect to the wavelength used (λ = 193 nm). The notation in Table (1) is the same in the following Table (2).

Table (1)
(Main specifications)
NA = 1.01
(Optical member specifications)
Surface number r dn optical member
1 ∞ 4 1.5603 (31a)
2 ∞ 0.5 1.436 (Lm3)
3 ∞ 5.818198 1.5603 (31ba)
4 -7.44717 0.3
5 -14.50616 5.044384 1.5603 (L11)
6 -12.05771 0.388954
7 -239.46501 4.885198 1.5603 (L12)
8 -23.76236 0.3
9 22.62569 3 1.5603 (L13)
10 20.89097 2.316897
11 53.81696 4.587583 1.5603 (L14)
12 -47.26678 5.97956
13 31.42431 6 1.5603 (L15)
14 -266.64134 2.072587
15 -70.4181 4.80664 1.5603 (L21)
16 16.94406 1.931975

[Second Embodiment]
FIG. 5 is a diagram schematically showing a lens configuration of the objective optical system according to the second example of the present embodiment. Referring to FIG. 5, in the objective optical system according to the second example, the positive lens 31ba is configured as a plano-convex lens having a convex surface with a strong curvature facing the exit side. The positive lens group 31bb includes a positive meniscus lens L11 having a concave surface directed toward the object side, a positive meniscus lens L12 having a concave surface directed toward the object side, a biconvex lens L13, and a negative lens having a convex surface directed toward the object side. It comprises a meniscus lens L14, a biconvex lens L15, and a biconvex lens L16. The negative lens group 31bc is composed of a biconcave lens L21.

  Also in the second embodiment, as in the first embodiment, the optical path between the pinhole member (first optical member) 31a and the positive lens (second optical member) 31ba has a wavelength λ = 193 nm of the used light. And filled with pure water Lm3 having a refractive index of 1.436. In the second embodiment, as in the first embodiment, all the optical members (parallel plane plates and lenses) constituting the objective optical system have a refraction of 1.5603 with respect to the wavelength λ = 193 nm of the used light. It is made of quartz having a ratio. The following table (2) lists the values of the specifications of the objective optical system according to the second example.

Table (2)
(Main specifications)
NA = 1.05
(Optical member specifications)
Surface number r dn optical member
1 ∞ 4 1.5603 (31a)
2 ∞ 0.5 1.436 (Lm3)
3 ∞ 5.94727 1.5603 (31ba)
4 -9.20733 0.309937
5 -16.33359 4.936574 1.5603 (L11)
6 -11.49463 0.3
7 -37.1881 4.35965 1.5603 (L12)
8 -19.14546 0.3
9 41.75681 5.333281 1.5603 (L13)
10 -68.65322 0.3
11 27.99985 5.062252 1.5603 (L14)
12 23.44547 2
13 56.97335 3.97153 1.5603 (L15)
14 -76.77456 0.3
15 43.43031 5.118584 1.5603 (L16)
16 -97.28291 1.260922
17 -32.95019 6 1.5603 (L21)
18 16.8344 2.070605

  As described above, in each embodiment, the optical path between the pinhole member 31a and the positive lens 31ba has pure water (refractive index greater than the incident-side maximum numerical aperture NA (1.01 or 1.05)). In general, since it is filled with medium Lm3, the light beam incident on the pinhole member 31a at the maximum incident angle corresponding to the maximum numerical aperture on the incident side is also a boundary between the plane on the emission side of the pinhole member 31a and the pure water Lm3. All the measurement light beams are effectively taken into the objective optical system without being totally reflected by the surface.

  6 and 7 are diagrams showing lateral aberrations of the objective optical system according to the first and second examples, respectively. In each aberration diagram, O indicates the object height. As is apparent from the respective aberration diagrams, it can be seen that the objective optical systems according to the first and second examples correct aberrations well.

  In the exposure apparatus of the above-described embodiment, the reticle (mask) is illuminated by the illumination device (illumination process), and the transfer pattern formed on the mask is exposed to the photosensitive substrate using the projection optical system (exposure process). Thus, a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, referring to the flowchart of FIG. 8 for an example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the present embodiment. I will explain.

  First, in step 301 of FIG. 8, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the one lot of wafers. Thereafter, in step 303, using the exposure apparatus of the present embodiment, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot via the projection optical system. Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer.

  Thereafter, a device pattern such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput. In steps 301 to 305, a metal is deposited on the wafer, a resist is applied on the metal film, and exposure, development, and etching processes are performed. Prior to these processes, on the wafer. It is needless to say that after forming a silicon oxide film, a resist may be applied on the silicon oxide film, and steps such as exposure, development, and etching may be performed.

  In the exposure apparatus of this embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 9, in a pattern formation process 401, a so-called photolithography process is performed in which the exposure pattern of the present embodiment is used to transfer and expose a mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate undergoes steps such as a developing step, an etching step, and a resist stripping step, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming step 402.

  Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three of R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembly step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.

  In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402, and a liquid crystal panel (liquid crystal cell) is obtained. ). Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

  In the above-described embodiment, the ArF excimer laser light source is used. However, the present invention is not limited to this, and other appropriate light sources such as a KrF excimer laser light source can also be used. In the above-described embodiment, the present invention is applied to the objective optical system for an aberration measuring apparatus that measures the wavefront aberration of the projection optical system. However, the present invention is not limited to this, and other general objective optics. For example, the objective optical system of a measuring device that measures the pupil transmittance distribution of an illumination optical system and a projection optical system, and the objective optical system of a measuring device that measures the polarization distribution of an illumination optical system and a projection optical system. The invention can be applied.

  In addition, the aberration measuring apparatus 30 of the above-described embodiment may be configured to be attachable to the wafer stage, or may be provided on a measurement stage different from the wafer stage. In the above-described embodiment, the present invention is applied to an aberration measuring apparatus for an immersion type exposure apparatus in which a liquid is filled between the projection optical system PL and a wafer W as a substrate. The present invention can also be applied to an aberration measuring apparatus for a dry type exposure apparatus in which a gas is filled between the optical system PL and the wafer W (substrate).

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure which shows typically the structure between a boundary lens and a wafer. It is a figure which shows schematically the internal structure of the aberration measuring device concerning this embodiment. It is a figure which shows schematically the lens structure of the objective optical system concerning 1st Example. It is a figure which shows schematically the lens structure of the objective optical system concerning 2nd Example. FIG. 3 is a lateral aberration diagram of the first example. It is a lateral aberration figure of 2nd Example. It is a flowchart of the method at the time of obtaining a semiconductor device. It is a flowchart of the method at the time of obtaining a liquid crystal display element.

Explanation of symbols

R reticle RST reticle stage PL projection optical system Lm1, Lm2, Lm3 pure water (liquid)
W Wafer TM Test mask 30 Aberration measuring device 31 Objective optical system 31a Pinhole member (first optical member)
31ba positive lens (second optical member)

Claims (8)

An objective optical system comprising, in order from the object side, a first optical member having a substantially parallel flat form and a second optical member having a positive refractive power with a convex surface facing the exit side,
An objective optical system, wherein an optical path between the first optical member and the second optical member is filled with a medium having a refractive index larger than the maximum numerical aperture on the incident side of the objective optical system. A positive lens group disposed on the exit side of the second optical member and having a positive refractive power; and a negative lens group disposed on the exit side of the positive lens group and having a negative refractive power. The objective optical system according to claim 1. 3. The objective optical system according to claim 1, wherein an object-side surface of the first optical member substantially coincides with an object surface of the objective optical system. 4. The objective optical system according to claim 1, wherein a predetermined pattern is formed on the object-side surface of the first optical member. 5. 5. The medium satisfying an optical path between the first optical member and the second optical member is the same type as a medium in contact with an object side surface of the first optical member. The objective optical system according to any one of the above. In an aberration measuring apparatus for measuring the wavefront aberration of an imaging optical system,
An aberration measuring apparatus comprising the objective optical system according to claim 1. The aberration measuring apparatus according to claim 6, wherein an object side surface of the first optical member in the objective optical system is positioned so as to substantially coincide with an image surface of the imaging optical system. . In an exposure apparatus that exposes a predetermined pattern onto a photosensitive substrate via a projection optical system,
An exposure apparatus comprising the aberration measuring apparatus according to claim 6 or 7 for measuring wavefront aberration of the projection optical system.

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