Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70225—Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/02—Catoptric systems, e.g. image erecting and reversing system
  • G02B17/026—Catoptric systems, e.g. image erecting and reversing system having static image erecting or reversing properties only
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/08—Catadioptric systems
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B17/00—Systems with reflecting surfaces, with or without refracting elements
  • G02B17/08—Catadioptric systems
  • G02B17/0892—Catadioptric systems specially adapted for the UV
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/20—Exposure; Apparatus therefor
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70275—Multiple projection paths, e.g. array of projection systems, microlens projection systems or tandem projection systems
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70216—Mask projection systems
  • G03F7/70341—Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply

Definitions

• the invention relates to a catadioptric projection objective having at least one concave mirror and at least one intermediate image.
• a preferred field of application is projection objectives for mi- crolithography which serve for imaging a pattern of a mask arranged in an object surface of the projection objective into an image field arranged in the image surface of the projection objective, with a de- magnifying imaging scale.
• Catadioptric projection objectives of the R-C-R type have been known for many years.
• Such an imaging system comprises three cascaded (or concatenated) imaging subsystems, that is to say has two intermediate images.
• a first, refractive subsystem (ab- breviation "R") generates a first real intermediate image of an object.
• a second, catadioptric or catoptric subsystem (abbreviation "C") with a concave mirror generates a real second intermediate image from the first intermediate image.
• a third, refractive subsystem images the second intermediate image into the image plane.
• One object of the invention is to provide catadioptric projection objectives of the R-C-R type which are suitable for use in wafer scanners and which make it possible to use masks which can also be used with refractive projection objectives or catadioptric projection objectives without "image flip".
• the object is achieved by means of a catadioptric projection objective for lithography having an even number of plane mirrors and an even number of concave mirrors and at least one intermediate image.
• the object is achieved by means of a catadioptric projection objective for lithography formed from a first subsystem, which forms a first intermediate image, a second subsystem, which forms a second intermediate image, and comprises a concave mirror near the pupil, and a third subsystem, which images the second intermediate image onto the image plane, wherein an even number of mirrors is arranged in between the object plane and the concave mirror and an odd number of mirrors is arranged in between the concave mirror and the image plane.
• the object is achieved by means of a projection objective for lithography formed from a first subsystem, which forms a first intermediate im- age, a second subsystem, which forms a second intermediate image, and comprises a concave mirror near the pupil, and a third subsystem, which images the second intermediate image onto the image plane, wherein an odd number of mirrors is arranged in between the object plane and the concave mirror and an even number of mirrors is arranged in between the concave mirror and the image plane.
• deflection system An arrangement of reflective surfaces that deflect bundles of rays from one part of the projection objective into another part.
• the deflection system comprises an image rotating reflection device, which is designed to effect an image rotation through 180°, that is to say a complete erection of an image, by multiple reflection at planar reflection surfaces situated at an angle with respect to one another.
• This can be realized in compact form by roof-type design of reflecting surfaces.
• a reflection prism (reflecting prism) is used for this purpose.
• the reflecting prism may be configured as a roof prism and contain a roof-type arrangement of planar reflecting surfaces. Reflection prisms in the manner of pentaprisms can also be used.
• the image rotating reflection device is embodied as a pure mirror system in the manner of an angular mirror.
• Fig. 1 schematically shows a reference system of the R-C-R type with image flip
• Fig. 2 shows different embodiments of image rotating reflection devices, a roof prism being illustrated in (a) and an angular mirror being illustrated in (b);
• Fig. 3 shows an embodiment of an R-C-R system with a roof prism in the pupil space of the first, refractive subsystem
• Fig. 4 shows an embodiment of an R-C-R system with a roof prism in the vicinity of the first intermediate image
• Fig. 5 shows an embodiment of an R-C-R system with a roof prism between the second and third subsystems
• Fig. 6 shows different embodiments of deflection systems in which a planar reflecting surface is formed by a reflecting inner surface of a prism
• Fig. 7 shows an embodiment of an R-C-R system in which the beam path leading to the concave mirror and the beam path leading away from the concave mirror cross in the region of the deflection system;
• Fig. 8 shows a variant of the system in Fig. 7 in which the reflecting surfaces of the deflection system are further away from the second intermediate image;
• Fig. 9 shows different variants of a deflection system with crossed and uncrossed beam path
• Fig. 10 shows exemplary embodiments of deflection systems with a physical beam splitter having a planar, polarization-selective reflection layer in combination with a plane mirror (a) and with a concave mirror (b);
• Fig. 11 shows an embodiment of an R-C-R system with a deflection system having a physical beam splitter in the pupil space of the first subsystem
• Fig. 12 shows an embodiment of an R-C-R system with a centered object field, the deflection system having a physical beam splitter;
• Fig. 13 shows an embodiment of an R-C-R system in which the deflection system comprises a physical beam splitter having two polarization-selective beam splitter layers that are offset parallel to one another;
• Fig. 14 shows an embodiment of an R-C-R system in which the deflection system has a physical beam splitter and a plane mirror arranged in the beam path upstream of the beam splitter;
• Fig. 15 (a) to (d) show different variants of deflection systems with a physical beam splitter and a deflection prism in the light path upstream and downstream of the beam splitter;
• Fig. 16 shows a lens section through an embodiment of an R-C-R system with a physical beam splitter, the first intermediate image being arranged upstream of the beam splitter and the second intermediate image being arranged between the beam splitter and a plane mirror;
• Fig. 17 shows a schematic illustration of the mirrors of a deflection system by means of which the optical axis of the projection objective is folded in two mutually perpendicular planes (three- dimensionally);
• Fig. 18 shows a lens section through a projection objective of the type illustrated in Fig. 17.
• optical axis denotes a straight line or a sequence of straight line sections through the centers of curvature of the optical compo- nents.
• the optical axis is folded at folding mirrors (deflection mirrors) or other reflective surfaces.
• the object is a mask (reticle) having the pattern of an integrated circuit; a different pattern, for example of a grating, may also be involved.
• the image is projected onto a wafer that is provided with a photoresist layer and serves as a substrate.
• Other substrates for example elements for liquid crystal displays or substrates for optical gratings, are also possible.
• Fig. 1 The traditional construction of a system of the R-C-R type is illustrated in Fig. 1 on the basis of a reference system REF - not associated with the invention - with "image flip".
• the imaging scale has opposite signs in two planes that are perpendicular to the optical axis OA and perpendicular to one another.
• the sys- tern serves for imaging a pattern arranged in an object plane OS of the projection objective into an image plane IS of the projection objective. It comprises three cascaded imaging subsystems, that is to say has precisely two real intermediate images.
• It has a first, refractive subsystem formed from a first lens group LG 1 and a second lens group LG2, a second, catadioptric subsystem formed from a concave mirror CM, a lens group LG21 near the field and a second lens group LG22, and a third, refractive subsystem formed from two lens groups LG31 and LG32. Situated between the lens groups LG11 and LG 12, and respectively between the lens groups LG31 and LG32, is a pupil surface (PS) in which an aperture diaphragm may be used.
• PS pupil surface
• the second subsystem may be embodied with or without the first group LG21 near the field (in this respect, see e.g. WO 2004/019128 for systems without a lens group near the field, or the applicant's US provisional application 60/571 ,533 with application date May 17, 2004 for systems with a lens group near the field.
• the disclosure of this provisional application is incorporated by reference in the content of this description.
• a deflection system (DS).
• the latter is realized by means of a prism DS in Fig. 1 , said prism's externally mirror- coated cathetus surfaces oriented at right angles to one another serving as reflecting surfaces.
• deflection system should be understood to mean an arrangement of reflective surfaces which guide the bundles of rays from one part of the system to the subsequent part of the system and connect the optical axes of the subsystems to one another, to be precise in particular such that the image plane IS and the object plane OS of the objective run parallel to one another.
• the position of the intermediate images relative to the deflection system and to the groups LG12, LG21 and LG31 present can vary.
• the positioning of the intermediate images in the vicinity of the deflection system is expedient.
• a first solution approach relates to the incorporation of a "roof edge" into the projection objective.
• the roof edge with a roof-type design of reflecting surfaces is intended to effect an image rotation through 180 degrees and preferably has two planar reflecting surfaces situated at a right angle with respect to one another.
• Said "roof edge” may be realized both by means of a half cube prism and by means of two combined reflecting surfaces. Two expedient types of embodiment are illustrated in Fig. 2(a) and 2(b).
• the relative arrangement of the reflecting surfaces is stable. Since the relative position of the reflective surfaces plays an important part, this may be advantageous.
• a first expedient position is in the first subsystem.
• Fig. 3 illustrates such an arrangement in which the roof edge is arranged in the pupil space of the first subsystem.
• a second expedient position for a roof edge is the vicinity of the first intermediate image.
• the latter arises downstream of the first subsystem, that is to say downstream of the group LG 12.
• the roof edge may be inserted between the first and second or between the second and third subsystems.
• Fig. 4 shows such an arrangement.
• a further expedient position is in the vicinity of the second intermediate image, that is to say between the second and third subsystems.
• Fig. 5 illustrates this arrangement.
• a second solution approach consists in incorporating a 90° deflection system formed from an even number of successive re- fleeting surfaces whose normals are parallel.
• Embodiments of angular mirrors having precisely two plane mirrors are appropriate here. Owing to the use in the divergent beam path, these arrangements can be used well in a manner free of vignetting (or shading) primarily at small apertures.
• Figures 9(a) to (d) show embodiments of the deflection system with a crossed and uncrossed beam path. Some beam guidances are also possible using prisms. By way of example, the beam guidance according to (a) can also be achieved using a pentaprism.
• a third solution approach is based on the use of a beam splitter cube with a beam splitter surface (BSS) in combination with a mirror in order to deflect the beam path by 90°.
• BSS beam splitter surface
• FIG. 10 An exemplary construction is illustrated in Fig. 10, on the one hand with a plane mirror PM and on the other hand with a curved mirror CM.
• the physical beam splitter has a planar, polarization- selective beam splitter surface BSS.
• a ⁇ /4 plate is inserted between the beam splitter and the mirror PM or CM.
• the reflecting surfaces of the mirrors may be aspherized or planar or spherically curved.
• a first preferred location for incorporating said deflection system is in the pupil space of the first subsystem.
• the construction is illustrated in Fig. 11.
• a further preferred incorporation location is in the vicinity of the intermediate images.
• Two further variants may be differentiated here: with a centered field and with an uncentered field.
• the beam splitter cube is incorporated in such a way that the field of the objective can be positioned in a manner centered with respect to the optical axis.
• Figure 12 illustrates a preferred arrangement.
• Fig. 16 shows an exemplary embodiment.
• the specification of the design shown in Fig.16 is summa- rized in tabular form in table 1.
• column 1 specifies the number of the refractive surface, reflective surface or surface distinguished in some other way
• column 2 specifies the radius r of the surface (in mm)
• column 3 specifies the distance d between the surface and the succeeding surface (in mm)
• column 4 specifies the material of a component
• column 5 specifies the maximum usable semidiameters in mm.
• the reflective surfaces are indicated in column 6.
• thirteen of the surfaces are aspherical, namely the surfaces 2, 7, 14, 19, 25, 29, 37, 41 , 55, 56, 58, 63 and 73.
• the reciprocal (1/r) of the radius specifies the surface curvature at the surface vertex and h specifies the distance between a surface point and the optical axis. Consequently, p(h) specifies said sagitta, that is to say the distance between the surface point and the surface vertex in the z direction, that is to say in the direction of the optical axis.
• the constants K, C1 , C2 ... are re- produced in table 1A.
• the image-side numerical aperture NA is 1 ,2, the imaging scale is 4:1.
• the system is designed for an image field with a size of 26 x 5 mm 2 .
• a second embodiment has the advantage that the spurious light can be reduced by means of a second polarization-selective beam splitter surface BSS.
• Said spurious light essentially comprises light which is transmitted by the beam splitter surface BSS instead of being reflected.
• a corresponding solution has also been proposed in a different context in the applicant's WO 2004 092801.
• Figure 13 illustrates an exemplary construction.
• FIG. 14 A preferred embodiment of the second variant is illustrated in Fig. 14.
• the beam path between object plane and concave mirror is folded by means of a plane mirror, and the beam splitter with the adjacent plane mirror in accordance with Fig. 10 is used for folding between the concave mirror and the image plane.
• the opposite order is also possible.
• Figure 14 illustrates this arrangement.
• Various other constructions of the deflection system with folding of the optical axis OA are shown in Fig. 15.
• the mirror has an aspheri- cal surface. This mirror can thus act on field-dependent aberrations since it is situated directly near the field.
• the intermediate image in direct proximity to the mirror may be positioned upstream of the mirror or downstream of the mirror in the beam propagation direction. It is thus possible to decide what subsystem the mirror belongs to.
• FIG. 17 A further variant is for the system to be folded 3-dimensionally.
• FIG. 17 A schematic diagram of this arrangement is illustrated in Fig. 17.
• the object field or object plane OS and image field or image plane IS are perpendicular to one another.
• a plurality of folding mirrors FM are provided, the folding planes of the folding mirrors FM1 and FM2 and also the folding planes of the folding mirrors FM2 and FM3 in each case being perpendicular to one another.
• the illustration of the lens groups has been dispensed with in the diagram.
• FIG. 18 A schematic perspective view of such a system with lens groups is illustrated in Fig. 18. Table 1

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Lenses (AREA)
• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
• Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)

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Applications Claiming Priority (2)

Publications (1)

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Citations (7)

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• 2006
  • 2006-01-28 KR KR1020077017879A patent/KR20070102533A/ko not_active Withdrawn
  • 2006-01-28 WO PCT/EP2006/000740 patent/WO2006081991A1/en not_active Ceased
  • 2006-01-28 EP EP06704356A patent/EP1844365A1/en not_active Withdrawn
  • 2006-01-28 JP JP2007553511A patent/JP2008529094A/ja active Pending
  • 2006-01-28 US US11/815,522 patent/US20090128896A1/en not_active Abandoned

Patent Citations (8)

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