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WO2003050587A2 - Objectif catadioptrique - Google Patents

Objectif catadioptrique Download PDF

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Publication number
WO2003050587A2
WO2003050587A2 PCT/EP2002/008037 EP0208037W WO03050587A2 WO 2003050587 A2 WO2003050587 A2 WO 2003050587A2 EP 0208037 W EP0208037 W EP 0208037W WO 03050587 A2 WO03050587 A2 WO 03050587A2
Authority
WO
WIPO (PCT)
Prior art keywords
lens
area
projection
mirror
image
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2002/008037
Other languages
German (de)
English (en)
Other versions
WO2003050587A3 (fr
Inventor
David R. Shafer
Alexander Epple
Wilhelm Ulrich
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Carl Zeiss SMT GmbH
Original Assignee
Carl Zeiss SMT GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carl Zeiss SMT GmbH filed Critical Carl Zeiss SMT GmbH
Priority to EP02747468A priority Critical patent/EP1456705A2/fr
Priority to JP2003551585A priority patent/JP2005512151A/ja
Priority to AU2002317875A priority patent/AU2002317875A1/en
Publication of WO2003050587A2 publication Critical patent/WO2003050587A2/fr
Publication of WO2003050587A3 publication Critical patent/WO2003050587A3/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • 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
    • 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
    • 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

Definitions

  • the invention relates to a catadioptric projection lens for imaging a pattern arranged in an object plane in an image plane.
  • Such projection objectives are used in projection exposure systems for the production of semiconductor components and other finely structured components, in particular in wafer scanners and wafer steppers. They are used to project patterns of photomasks or reticules, which are hereinafter generally referred to as masks or reticles, onto an object coated with a light-sensitive layer with the highest resolution on a reduced scale.
  • NA numerical aperture
  • catadioptric systems in which refractive and reflective components, in particular thus lenses and mirrors, are combined are predominantly used for high-resolution projection lenses of the type mentioned.
  • Systems with a physical beam splitter for example in the form of a beam splitter cube (BSC, beam splitter cube), have the advantage that axial (on-axis) systems can be implemented.
  • axial (on-axis) systems can be implemented.
  • polarization-selective mirror surfaces are used, which have a reflecting or transmitting effect depending on the preferred polarization direction of the incident radiation.
  • suitable transparent materials are hardly available in the large volumes required.
  • the production of the optically effective beam splitter layers within the beam splitter cubes can cause considerable difficulties. This is especially true when there are large incidence angles on the mirror surface and / or there is a large angular bandwidth of the radiation occurring.
  • EP-A-0 475 020 An example of a system with a physical beam splitter is shown in EP-A-0 475 020 (corresponding to US-A-5, 052,763).
  • the mask lies directly on a beam splitter cube, and the intermediate image lies behind the beam splitter surface inside the beam splitter cube.
  • Another example is shown in US-A-5, 808,805 and the associated continuation application US-A-5, 999,333.
  • US-A-5, 999,333 Another example is shown in US-A-5, 999,333.
  • Lens group with positive refractive power The collected light beam is first directed from the polarization beam splitter surface in the direction of a concave mirror and is reflected by the latter back into the beam splitter cube and through the beam splitter surface in the direction of the subsequent lens group with a generally positive refractive power.
  • the intermediate image lies within the beam splitter cube in the immediate vicinity of the beam splitter surface.
  • Such a catadioptric reduction lens is described in EP-A-0 989 434 (corresponding to US Serial No. 09/364382).
  • a catadioptric first objective part with a concave mirror and a beam deflection device are arranged between the object plane and the image plane, and a dioptric second objective part is arranged behind this.
  • Beam deflecting device has a first mirror surface for deflecting the radiation coming from the object plane to the concave mirror and a second mirror surface for deflecting the radiation reflected by the latter to the second objective part, which contains only refractive elements.
  • a positive lens is arranged between the object plane and the first mirror surface, the refractive power of which is dimensioned such that the concave mirror lies in the region of the pupil.
  • the catadioptric first lens part generates a real intermediate image, which lies at a short distance behind the second mirror surface and at a distance from the first lens of the second lens part. The intermediate image is thus freely accessible, which z. B. can be used to attach a light field diaphragm. Large maximum incidence angles, in particular on the first mirror surface, place increased demands on the coating of the mirrors in order to ensure a largely uniform reflection of the entire incident radiation.
  • US-A-6, 157,498 shows a similar structure in which the intermediate image is on or near the mirror surface of the Beam deflector is located. Some lenses of the second objective part are arranged between the latter and a deflection mirror in the second objective part. An aspherical surface is also arranged in the immediate vicinity or in the intermediate image. This is only intended to correct distortion without affecting other image errors.
  • DE 197 26 058 shows a projection objective with a reducing catadiopthic subsystem and an intermediate image in the vicinity of a deflecting mirror of a beam deflecting device.
  • JP-A-10010429 A similar lens construction, in which the intermediate image generated by the catadioptic lens part is also in the vicinity of the single deflection mirror of the beam deflection device, is shown in JP-A-10010429.
  • the lens surface closest to the deflecting mirror of the subsequent dioptric lens part is aspherical in order to contribute particularly effectively to correcting the distortion.
  • Catadioptric systems with beam splitters generally have a group of double-pass lenses that are traversed on the light path from the object field to the concave mirror and on the light path from the concave mirror to the image field. It is proposed in US Pat. No. 5,691,802 that this lens group has positive refractive power, which should lead to a smaller diameter of the concave mirror.
  • a system with a single double-pass positive lens in the vicinity of a deflection mirror of the beam guide is described in US Pat. No. 6,157,498.
  • Lenses that are run through twice generally have the disadvantage that their negative effects on the light beam, in particular reflection and absorption, are introduced twice, while the advantage of introducing a degree of freedom for the correction of the image is present only once, so that there is a compromise between the effects the two light beam directions must be found.
  • a projection objective is to be created which is moderate
  • the invention proposes catadioptric projection objectives with the features of the independent claims. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated by reference into the content of the description.
  • a catadioptric projection lens in accordance with one aspect of the invention is designed to image a pattern arranged in an object plane into an image plane while generating a real intermediate image. It has a catadiopthic first objective part with a concave mirror and a beam deflection device between the object plane and the image plane and a second objective part behind the beam deflection device, which is preferably dioptric, that is to say has no imaging mirror surfaces.
  • the beam deflection device has a first mirror surface for deflecting the radiation coming from the object plane to the concave mirror. Positive refractive power is arranged behind the first mirror surface and thus between it and the concave mirror in an optical close-up range of the object plane. This close-up optical range is characterized in particular by the fact that the main beam height of the image is greater than the edge beam height there.
  • the positive refractive power between the object plane and the concave mirror is intended to help ensure that a pupil surface of the projection objective lies in the region of the concave mirror, ie either on the concave mirror or in the vicinity thereof.
  • a positive refractive power of suitable strength in the optical close-up range of the object plane also enables object-telecentricity of the objective to be achieved, which is advantageous for avoiding defocus errors on the object side.
  • the arrangement of the positive refractive power behind the first mirror surface makes it possible for the main rays of the image, which are telecentric in the object plane or largely parallel to the optical axis of the system run, also impinge on the first mirror surface parallel to the optical axis.
  • the positive refractive power arranged behind the first mirror surface is preferably generated by a single lens.
  • the angle of incidence of the radiation impinging on the first mirror surface is not greater than approximately 68 ° with a numerical aperture on the objective side of 0.2125, it being possible to achieve maximum angle of incidence of not more than 66 °.
  • the invention makes it possible to construct lenses in which the incidence angles on the first mirror surface are not greater than ⁇ 0 , where:
  • ß is the imaging scale of the projection lens
  • NA is the numerical aperture on the image side
  • ⁇ H o A is the angle that extends from a plane perpendicular to the object plane and possibly the image plane Part of the optical axis and part of the optical axis in the region of a horizontal arm carrying the concave mirror is enclosed.
  • the first mirror surface is arranged at an angle of inclination that deviates from 45 ° obliquely to the optical axis of the projection objective.
  • the angle of inclination can be, for example, 50 ° or above, in particular between 50 ° and 55 °.
  • the positive refractive power arranged close behind the first mirror surface has a greater refractive effect on the marginal rays of the image due to a greater distance from the object plane than known designs and thus due to larger marginal ray heights.
  • This can be used to construct the optical components following the positive refractive power, in particular the optical components of a mirror group comprising the concave mirror, with a reduced diameter with unchanged size compared to conventional designs. This promotes a material-saving construction of the catadioptic lens part.
  • the beam deflection device has a second mirror surface for deflecting the radiation coming from the concave mirror to the second objective part and that the intermediate beam intermediate image is arranged in the vicinity of the second mirror surface.
  • This proximity to the second mirror surface can in particular be so large that the edge ray height at the second mirror surface is less than 20%, in particular less than 10%, of half the diameter of the concave mirror.
  • the intermediate ray intermediate image can also essentially fall onto the second mirror surface.
  • An intermediate ray of the image in the immediate vicinity the second mirror surface is favorable for minimizing the light conductance of the lens and thus facilitates the correction of aberrations.
  • the intermediate ray image is not essentially on the second mirror surface, it is preferred if the intermediate ray image lies in front of the second mirror surface in the direction of light travel.
  • Embodiments are particularly preferred in which positive refractive power is arranged in the vicinity of the intermediate image, in particular between the intermediate image and the second mirror surface.
  • positive refractive power is arranged in the vicinity of the intermediate image, in particular between the intermediate image and the second mirror surface.
  • a pupil is located near the concave mirror or main mirror.
  • the imaging scale ⁇ M from the object plane to the intermediate image can thereby be set close to 1: 1 and in particular be greater than approximately 0.95.
  • a positive refractive power preferably provided by a single positive lens in the direction of light movement behind the intermediate image can counteract excessive divergence of main rays after the intermediate image.
  • the diameters of the lenses of the second lens part following the intermediate image can be kept small, which enables a material-saving construction of this lens part.
  • Advantageous projection lenses are characterized in that in a double-irradiated area of the projection lens, in particular between the beam deflection device and the concave mirror, at least one multi-area lens is arranged, which has a first lens area irradiated in a first direction of passage and a second lens area irradiated in a second direction of passage, wherein the first lens area and the second lens area do not overlap on at least one side of the lens. If at least one of the two lens sides do not overlap the "footprints" of the beam paths, such a multi-area lens allows two independently operating lenses to be brought geometrically to a common location.
  • a multi-area lens can be clearly distinguished from a conventional double-pass lens, since in the case of a multi-area lens this type can be influenced independently of one another by suitable independent shaping of the refractive surfaces of the lens areas.
  • a lens arrangement with at least one half lens or partial lens can also be arranged at the location of a one-piece multi-area lens, in order to influence the beams of rays traveling past one another independently of one another.
  • the positive refractive power provided immediately behind the first mirror surface and the positive refractive power provided in front of the second mirror surface are provided by such a multi-area lens.
  • Manufacturing advantages can be achieved if of the two lens surfaces of the multi-area lens (entrance side and exit side or vice versa) only one lens area has areas of different curvature.
  • the production can then be carried out in such a way that the lens is first prefabricated in the form of one of the two surface parts. This is preferably a spherical shape. This area then already has the intended curvature.
  • the other surface part can then be provided with a curvature by means of targeted post-processing, which differs from the curvature of the starting surface.
  • a polishing which may be computer numerically controlled can be used, in particular with the aid of ion beams.
  • a significant expansion of the design space can be achieved if the multi-area lens has at least one lens surface which is aspherical in at least one partial area.
  • the multi-area lens has at least one lens surface which is aspherical in at least one partial area.
  • at least one of these areas is aspherical.
  • Projection lenses of the type described here with an off-axis object field, a catadiopthic first lens part and a geometric beam splitter working with at least one deflection mirror and a single concave mirror, an intermediate image and a preferably refractive second lens part can have at least one plane perpendicular to an optical axis, in which a first beam which runs to the concave mirror and a second beam which runs back from the concave mirror run past each other without mutual overlap.
  • at least one half lens or partial lens is arranged in the area of this plane, which is irradiated independently in two partial areas, which breaks one of the beam bundles and is not touched by the other beam bundle or does not reach into its beam path.
  • Two such partial lenses can be arranged in the plane, each of which acts independently of one another on one of the beam bundles running past one another.
  • Such embodiments are favorable in terms of frame technology which one or, if available, two half lenses are attached to a transparent, disc-shaped carrier, for example on a lens or a plane-parallel plate. The attachment can be done for example by wringing or cementing or gluing.
  • the transparent body of the carrier can be mounted in a substantially ring-shaped frame along its annular edge.
  • the lenses arranged in the separately traversed plane are preferably rotationally symmetrical in this area with respect to the optical axis. As a result, the system remains a centered, optical system, which is advantageous in terms of design and manufacture.
  • a group of optical elements which comprises the concave mirror and one or more double-swept lenses, has an imaging scale that differs significantly from 1. In particular, this can be between 0.5 and 0.95 or between 1.05 and 1.2. It is thereby achieved that the angular distributions of the two beam bundles that pass each other in the area of the half lenses or the multi-area lens differ significantly. As a result, even relatively similar shapes of the separately traversed lens surfaces have different effects on the image correction.
  • a positive refractive power lying between the object plane and the concave mirror can be arranged largely or completely behind the first mirror surface, it is possible to construct the projection lens in such a way that no or only a small refractive power is arranged between the object plane and the first mirror surface. In this area, for example, only a largely plane-parallel entry plate can be provided. This can perform two functions. On the one hand, an interior of the projection lens that has been flushed with an inert gas, for example helium, can against the outside, which may have been flushed with another gas, for example nitrogen. Furthermore, the imaging performance of the projection lens becomes less sensitive to pressure fluctuations due to the flat interface of the lens with the surrounding medium.
  • an inert gas for example helium
  • the geometric space between the entrance element and the first mirror surface can be free of optical components, in particular free of positive lenses, which enables a compact construction in this area.
  • the first optical element is formed by a negative lens. If negative refractive power is arranged between the object plane and the first mirror surface, that which is in any case low in the case of projection objectives according to the invention
  • Angular load on the first mirror surface can be further reduced.
  • vignetting-free mapping is possible with even less effort.
  • the entry side of the negative lens is preferably largely flat in order to be able to use the described advantages of pressure stabilization.
  • one or more aspherical surfaces can be provided in one embodiment.
  • a larger number of aspheres is provided, but preferably no more than seven.
  • it is particularly expedient if at least one aspherical surface is arranged in the area of a diaphragm plane.
  • a particularly effective correction is given here if, for this surface, the ratio between the edge jet height on the surface and the radius of the opening of the Aperture is between approximately 0.8 and approximately 1.2. The edge beam height should therefore be close to the maximum edge beam height in the diaphragm area for the aspherical surface.
  • At least one asphere is arranged near the field and at least one asphere near a system diaphragm. This makes it possible to provide a sufficient correction for all of the imaging errors addressed.
  • the projection lenses according to the invention have at least one
  • FIG. 1 is a longitudinal sectional view of a first embodiment of a projection lens
  • Fig. 3 is an enlarged view of the area of the
  • Fig. 4 is a longitudinal sectional view of a third embodiment of a
  • FIG. 5 shows a longitudinal sectional illustration of a fourth embodiment of a projection objective
  • FIG. 6 shows a longitudinal sectional illustration of a fifth embodiment of a projection objective
  • Fig. 7 is a longitudinal sectional view of a sixth embodiment of a projection lens
  • FIG. 8 shows an embodiment of a microlithography projection exposure system according to the invention.
  • optical axis denotes a straight line or a sequence of straight line sections through the centers of curvature of the optical components.
  • the optical axis is folded on deflecting mirrors or other reflective surfaces.
  • Direction and distances are described as “image-side” if they are in the direction of the image plane or the substrate to be exposed located there are directed and as "object side” if they are directed towards the object with respect to the optical axis.
  • the object is a mask (reticle) with the pattern of an integrated circuit, but it can also be a different pattern, for example a grid.
  • the image is formed on a wafer serving as a substrate and provided with a photoresist layer, but other substrates, for example elements for liquid crystal displays or substrates for optical gratings, are also possible.
  • FIG. 1 A typical construction of a variant of a catadiopthic reduction lens 1 according to the invention is shown in FIG. 1 using a first exemplary embodiment. It is used to reproduce a pattern of a reticle or the like arranged in an object plane 2 in a reduced scale, for example in a ratio of 4: 1, while producing a single real intermediate image 3 in an image plane 4 lying parallel to the object plane 2.
  • the objective 1 has a catadiopthic first objective part 5 with a concave mirror 6 and a beam deflection device 7, and behind the beam deflection device a dioptric second objective part 8, which contains exclusively refractive optical components.
  • the beam deflection device 7 is as
  • Mirror prism formed and has a first, flat mirror surface 9 for deflecting the radiation coming from the object plane 2 in the direction of the concave mirror, and a flat second mirror surface 10 arranged at right angles to the first mirror surface for deflecting the reflected from the imaging concave mirror 6
  • the second mirror surface 10 can also be omitted. Then, without further deflection mirrors, the object plane and the image plane would be essentially perpendicular to one another. Folding can also be provided within the refractive objective part 8.
  • the light from an illumination system (not shown) on the side of the object plane 2 facing away from the image enters the projection objective and first passes through the mask arranged in the image plane.
  • the transmitted light then passes through a plane-parallel plate 11 arranged between the object plane 2 and the beam deflection device 7 and is then deflected by the folding mirror 9 of the beam splitter 7 in the direction of a mirror group 12.
  • the folding mirror 9 is oriented at an angle deviating from 45 ° to the optical axis 15 of the preceding lens part in such a way that the deflection takes place at a deflection angle of more than 90 °, in the example approximately 103 ° to 105 °.
  • the light reflected by the concave mirror 6 and returned to the beam deflection device 7 by the double-pass negative lenses 13, 14 is deflected by the second folding mirror 10 of the beam deflection device 7 in the direction of the dioptric second objective part 8.
  • the real intermediate image 3 is generated in the vicinity of the second folding mirror 10 in the direction of light travel.
  • the optical axis 16 of the second objective part 8 runs parallel to the optical axis 15 of the input part and thus allows a parallel arrangement between the object plane 2 and the image plane 4, which enables simple scanner operation.
  • the catadioptric first objective part 5 has a biconvex positive lens 20 which is arranged in the immediate vicinity of the beam deflection device 7 and both in the light path between the first mirror surface 9 and the concave mirror 6 and in the light path between the concave mirror 6 and the second mirror surface 10 provides positive refractive power in the immediate vicinity of the mirror surfaces 9, 10.
  • the double-spherical positive lens 20 in this embodiment is used as a multi-area lens, the first lens area 30 used on the way to the concave mirror 6 and the second lens area 31 used on the light path to the second mirror 10 not overlapping one another.
  • the refractive power provided by the lens regions 30, 31 can in principle also be provided by separate, mutually independent lenses.
  • the lenses of the second lens part 8 can be functionally subdivided into a transfer group 41 and a focusing group 42 and together serve to image the intermediate image 3 which arises in front of the second mirror surface 10 in the image plane 4.
  • the lens 43 closest to the intermediate image is designed as a positive meniscus lens with surfaces curved toward the object. This is followed by an oppositely curved meniscus lens 44 with a slightly negative refractive power. At a greater distance follows a negative meniscus lens 45 with surfaces curved toward the object, followed by a biconvex positive lens 46 as the last lens of the transfer group 41.
  • Table 1 summarizes the specification of the design in tabular form.
  • Column 1 gives the number of the refractive, reflecting or otherwise distinguished surface F
  • column 2 the radius r of the surface (in mm) and column 3 the distance d of the surface from the next surface (in mm)
  • column 4 referred to as the thickness the refractive index of the material of the component, which follows the entry surface, referred to as the index.
  • Column 5 shows the reflecting surfaces
  • column 6 shows the optically usable free diameter D of the optical components in mm.
  • the total length L of the lens between the object and image plane is approximately 1230 mm.
  • seven of the surfaces namely the surfaces F9 and F15, F23, F27, F30, F34, F41 and F49 are aspherical.
  • the aspheres are identified by double dashes in the figure.
  • Table 2 shows the corresponding aspherical data, the arrow heights of the aspherical surfaces being calculated according to the following rule:
  • p (h) [((1 / r) h) / (1 -rSQRT (1 - (1 + K) (1 / r) 2 h 2 )] + C1 * h 4 + C2 * h 6 + .. ..
  • the reciprocal (1 / r) of the radius indicates the surface curvature in the surface vertex and h the distance of a surface point from the optical axis.
  • p (h) gives this arrow height, ie the distance of the surface point from the surface vertex in the z direction, ie in the direction of the optical axis.
  • the constants K, C1, C2 ... are shown in Table 2.
  • the numerical aperture NA on the image side is 0.85, the imaging scale is 4: 1.
  • the system is designed for an image field of size 26 x 5.5 mm 2 .
  • the system is double telecentric.
  • the optical system Since there is no refractive power between the object plane 2 and the first folding 9, the angles occurring at the folding mirror 9 between the optical axis 15 and the main beam or the marginal beam correspond exactly to the corresponding beam angles in the object plane 2.
  • the folding of the beam path at the first deflecting mirror 9 by more than 90 ° is favorable for a large working distance across the entire width of the lens.
  • the positive lens 20 arranged in the light path behind the first mirror surface 9 between the latter and the concave mirror 6 is arranged in an optical close range of the object plane 2, in which the main beam height of the outermost field point of the image is greater than the edge beam height.
  • the main beam height here is the beam height of a field edge beam which crosses the optical axis in the area of the pupil.
  • the edge beam height is the beam height of a field center beam that leads to the edge of the system aperture.
  • the positive refractive power arranged directly behind the first folding mirror in conjunction with the vanishing refractive power between the object plane and the first folding mirror, causes the main rays of the image to fall onto the first mirror surface 9 axially parallel in the case of object-side telecentricity. In comparison to designs in which positive refractive power is arranged in front of the first folding mirror 9, this leads to significantly smaller incidence angles of the radiation impinging on the first mirror surface 9. In the embodiment shown, these incidence angles are not greater than approximately 68 °, with a maximum incidence angle of approx.
  • the positive lens 20 has a greater refractive effect on the edge rays of the image due to a relatively large distance from the object plane 2 and thus a larger edge ray height.
  • the diameter of the mirror group 12 and, in particular, of the concave mirror 6 can be kept small, which brings advantages in terms of production technology and construction. If object-side telecentricity is not required or desired, the refractive power of the positive lens 20 arranged in the vicinity of the object plane can be reduced accordingly, which also influences the incidence angle on the first mirror 9.
  • the two negative meniscus lenses 13, 14 immediately in front of the concave mirror 6 ensure the correction of the chromatic longitudinal aberration CHL.
  • positive refractive power is also arranged in the light path between the concave mirror 6 and the second mirror surface 10 in the immediate vicinity of the mirror surface. This is also provided by the positive lens 20.
  • the positive refractive power arranged in front of the second folding mirror 10 approximately collimates the main beam and thus makes it possible to manufacture the subsequent lenses of the dioptric lens part 8 with relatively small diameters, thereby promoting a material-saving design.
  • the refractive powers of the lens region of the positive lens 20 and the mirror group 12 which is irradiated directly behind the first folding mirror 9 are dimensioned such that the real intermediate image 3 of the image is arranged in the vicinity of the second mirror surface 10. More precisely the paraxial intermediate image 25 essentially on the lens surface 26 of the positive lens 20 facing away from the beam deflection device 7, i.e. in the light path between the concave mirror 6 and folding mirror 10 on the entry side of the positive lens 20, while the marginal ray intermediate image is closer to, but in front of, the second mirror surface ,
  • the intermediate image is therefore preferably in front of the second mirror surface 10, in particular in such a way that positive refractive power is still arranged between the paraxial intermediate image and this second mirror surface. Since the intermediate image falls in the vicinity of the second folding mirror 10, the light conductance of the whole can
  • Projection lenses with a constant field size can be minimized.
  • the extensive symmetry of the arrangement, in which the pupil lies in the vicinity of the main mirror 6, means that the magnification ßivi of the catadiopthic first objective part is close to 1: 1 and generally above approximately 0.95.
  • the positive refractive power provided in the immediate vicinity of the mirror surfaces 9, 10, which acts on the one hand in the light path between the first mirror surface 9 and the concave mirror and on the other hand in the light path between the concave mirror 6 and the second mirror surface 10, is provided by a single, one-piece multi-area lens, namely the positive lens 20. It has a first lens region 30, which is irradiated on the way from the first folding mirror 9 to the concave mirror 6, and a second lens region 31, which is irradiated on the light path from the concave mirror 6 to the second folding mirror 10.
  • the lens areas 30, 31 do not overlap either on the side facing the folding mirrors 9, 10 or on the side facing the mirror group 12, so that the lens areas are used completely independently of one another. Accordingly, the optical effect of the lens area 30, 31 can also be achieved by separate lenses be achieved. However, the union in a single lens facilitates the construction of the lens.
  • a special feature of the refractive second lens part 8 is that there is at least one negative-positive lens group, in which a diverging air space is arranged between the negative lens and the subsequent positive lens, which can have, in particular, the geometric shape of a convex-concave lens.
  • Such lens sequences near the diaphragm are particularly favorable.
  • two such lens groups 47, 48 and 49, 50 are present in front of the aperture 60, in which a lens 47 and 49 with a concave surface on the image side is followed by a meniscus-shaped running space.
  • Numbering of the optical elements or assemblies corresponds to the numbering of the embodiment according to FIG. 1.
  • the multi-range lens 120 of positive refractive power which is arranged in the immediate vicinity of the folding mirrors 9, 10, is constructed as a “split” lens.
  • the area that encompasses the beam deflection device 7 and the multi-range lens 120 is for clarification 3, schematically shown enlarged in Fig. 3.
  • the lens surface 121 facing the folding mirrors 9, 10 and curved in this direction is physically divided such that the lens region 130 assigned to the first folding mirror 9 has a different refractive power than that lens area 131 assigned to second folding mirror 10. This is brought about by different curvatures of the entrance surface 123 and the exit surface 124.
  • Such multi-area lenses of different refractive power increase the design scope for such projection objectives.
  • a preferred production method provides for the lens 120 to be produced from a single blank.
  • the two surface parts 123, 124 should have a slight deformation relative to one another. This can be achieved in a simple manner by first prefabricating the surface provided as a divided surface 121 in the form of one of the two surface parts in a manner known per se. Then the surface portion for which a surface shape deviating from this surface shape is provided is worked out from the first surface portion by targeted polishing. For this purpose, surface shaping with the aid of ion beams is preferably provided. The processing time is essentially proportional to the necessary volume removal. In the embodiment shown in FIG.
  • the surface part 124 is aspherical, while the surface part 123 is spherical.
  • the aspherization can be used to simulate different deflections of the lens regions 130, 131 in the respective optical beam paths that are separate from one another. This enables a significant expansion of the design space.
  • the in Figs. 1 and 2 embodiments have as a first optical element 1 1 a plane parallel plate.
  • the interior of the projection lens that has been flushed with helium in the example lenses can be sealed off from the outside, which can be flushed with nitrogen, for example.
  • the flat outer interface of the lens makes the design significantly less sensitive to pressure fluctuations with respect to the surrounding medium. This is essentially due to a reduced contribution of the Pezval sum and thus the pressure dependence of the field curvature.
  • the specification for the embodiment of a projection lens 200 according to FIG. 4 is given in Tables 5 and 6.
  • the numbering of the optical elements or of the optical assemblies corresponds to the numbering in the previous embodiments.
  • a negative refractive power is provided here between the object plane 2 and the first mirror surface 9.
  • This is provided by a negative lens 21 1, which has a flat entrance surface and a concave exit surface curved towards the object plane.
  • the negative refractive power provided thereby reduces the angular load on the first folding mirror 9 again in comparison to the above embodiments and makes the vignetting problem of the design favorable. Since the entry surface is flat, all advantages of flat entry surfaces with regard to pressure stabilization are retained. For example, the maximum incidence angle can be reduced by approximately 0.3 ° in comparison to the embodiment according to FIG. 1.
  • the design modification is also characterized by the fact that here the paraxial intermediate image 225 is clearly ahead of the
  • the primary mirror 6 facing lens surface of the multi-range lens 220 is.
  • FIG. 5 shows an embodiment of a projection objective 300, the specification of which is given in tables 7 and 8.
  • This design modification like the embodiment according to FIG. 1, has a plane-parallel entry element 31 1 and a double-spherical multi-area lens 320 arranged near the beam deflection device 7, which in other embodiments can also be at least partially designed as an aspherical lens.
  • a special feature of the design is that here the easily recognizable intermediate ray intermediate image 326, as well as that closer to Concave mirror arranged, paraxial intermediate image (not shown) is arranged at a clear distance outside the multi-area lens 320 between the latter and the concave mirror. The entire intermediate image is therefore outside of optical material.
  • the footprints of the beam paths do not overlap on both sides of the multi-range lens 320.
  • This position of the intermediate image completely outside of optical material on the side of the multi-area lens facing away from the beam deflection device can be particularly advantageous if no optical material of high quality, in particular high material homogeneity, is to be used for the multi-area lens 320, because such material is not available, for example or is too expensive. Because it can be avoided that any defects within the lens material are imaged in the image plane.
  • the design places higher demands on corrective measures, since this position of the intermediate image corresponds to a spherical undercorrection which is opposite to a natural tendency of such systems for spherical overcorrection.
  • the undercorrection of the intermediate image is primarily effected here by a suitable shape of an asphere in the mirror group.
  • FIG. 6 It can be seen from FIG. 6 that many of the advantages described here can be used regardless of which folding geometry is set with the aid of the beam deflection device and, if appropriate, further mirror surfaces.
  • the design in FIG. 6 is derived from the design shown in FIG. 1, the shapes of the lenses being retained. Corresponding elements are therefore designated with the same reference symbols.
  • the embodiment of the projection objective 1 ′ in FIG. 6 is characterized in that the light coming from the object plane 2, after passing through the plane-parallel entrance plate 11 and the positive lens 20 used in two beam directions, first strikes the concave mirror 6 in order to pass from it Direction of the first mirror surface 9 of the beam deflection device 7 to be reflected.
  • a deflection mirror 59 is arranged between the subsequent transfer group 41 and the focusing group 42 following this in order to enable a parallel alignment of the object plane and image plane.
  • the intermediate image 3 lies here in front of the first mirror surface 9, with the paraxial intermediate image (not shown) on the entry surface of the positive lens 20 facing the concave mirror 6 and the intermediate beam intermediate image between this and the deflecting mirror 9. It can be seen that no optical component is arranged in the space between the entry plate 11 and the deflecting mirror 9, so that between the object plane and
  • Beam deflecting device 7 a compact, axially compact design is possible. It can also be seen that the spherical lens surface of the positive lens 20 facing the beam deflection device 7 is used independently of the light bundle running between the object plane and the concave mirror and the bundle running between the concave mirror and the first mirror surface 9, since the beam bundles do not overlap on this side.
  • the one-piece multi-range lens 20 can be used to simulate the optical effect of two independent lenses with different deflections.
  • the wavefront correction in the image field is approximately 1% r.m.s. the wavelength (157nm) over the entire field.
  • the intermediate image 3 is generated by a catadiopthic, first objective part 5 with a geometric beam splitter 7, the first mirror surface 9 is a reflective rear side of a prism 401.
  • the group of two negative lenses arranged close to the concave mirror 6 is run through twice.
  • the second mirror surface 10 of the beam deflection device is arranged near the intermediate image.
  • the subsequent, refractive second lens part 8 has an aperture plane 402 and is constructed according to known techniques. Aspherical lens surfaces serve to reduce the number of lenses in view of the requirements for high NA and the transmission problems at 157 nm, as well as the availability and the price of calcium fluoride lenses.
  • the negative lenses of mirror group 12 create a reserve for the axial color error and the increase in the Petzval sum, which are introduced through the positive lenses.
  • the optical axis 15 on the object field and the optical axis 16 in the refractive second lens part 8 are parallel in order to achieve a parallel position of the object plane and image plane. In addition, they are coaxial or only slightly offset to one side.
  • the optical axis 17 of the part between the folding mirrors 9, 10 and the concave mirror deviates from this at an optimized angle in order to enable the folding mirrors 9, 10 to be arranged without vignetting.
  • Other folding variants are also possible within the scope of the design, for example an h-folding according to FIG. 6.
  • Beam splitting in other types of catadioptric projection lenses Separately in the light bundles that run past each other through the region 404, two half lenses or partial lenses 405, 406 are arranged, which represent a special feature of this design.
  • the half lenses 405, 406 each have positive refractive power, as a result of which the diameter of the beam in the region of the mirror group 12 is kept small.
  • the division of the beam bundles at the deflecting mirrors 9, 10 is simplified and the off-axis deviation of the object field can be reduced.
  • the refractive power of the positive half lens 405 arranged near the object plane influences the telecentricity on the object side, so that telecentric and non-telecentric variants are possible through a suitable choice of the refractive power.
  • the half lens 405, ie the positive refractive power between the object plane and the concave mirror can also be omitted.
  • Both half lenses 405 and 406 have refractive surfaces which are rotationally symmetrical with respect to the optical axis 17 of the objective part leading to the concave mirror. Accordingly, the entire projection lens is a centered, optical system.
  • the surface with the greater curvature faces the object field
  • the second half lens 406 has its more curved lens surface on the side facing away from the second mirror surface 10 and facing the concave mirror 6
  • the beam entry surfaces are each curved more than the beam exit surfaces.
  • the beam divergence in the second half lens 406 is greater than in the first half lens 405, since the combination of the concave mirror 6 and the upstream negative lenses has a reduced magnification. Accordingly, the half lenses 405, 406 have different corrective influences on the image. This cannot be achieved with a single rotationally symmetrical lens instead of the two half lenses.
  • a field lens between the object plane 2 and the first mirror surface 9 is optional.
  • Beam splitting and folding can be achieved by flat deflecting mirrors or by rear surfaces of prisms. Both a telecentric and a homocentric arrangement of the main beam are possible.
  • the arrangement of the intermediate image 3 in the vicinity of a folding mirror is advantageous for reducing or avoiding vignetting. If only one lens surface is different for the two beams, then the sides near the object field or near the intermediate image are preferably selected for this purpose, in order to achieve a stronger influence on field-specific aberrations.
  • the measures described here can reduce vignetting effects to such an extent that the object field can be moved close to the optical axis, with the consequence that the field radius to be corrected is small. This reduces all necessary lens diameters, which favors a material-saving design.
  • the correction of image errors is simplified by the additional degrees of freedom for the design.
  • all transparent, optical components consist of the same material, namely calcium fluoride.
  • other materials which are transparent at the working wavelength can also be used, in particular the fluoride crystal materials mentioned at the outset.
  • at least one second material can also be used, for example to support the chromatic correction.
  • the advantages of the invention can of course also be used in systems for other working wavelengths in the ultraviolet range, for example for 248 nm or 193 nm. Since only one lens material is used in the embodiments shown, it is particularly easy for the person skilled in the art to adapt the designs shown to other wavelengths , Especially for systems for Larger wavelengths can also be used for other lens materials, for example synthetic quartz glass for all or some optical components.
  • the beam deflection device can have a first and a second mirror surface, the mirror surfaces being designed as polarization-selective mirror surfaces which can coincide geometrically.
  • the mirror surfaces can e.g. be arranged in a beam splitter block (BSC).
  • a wafer scanner 150 is shown schematically by way of example in FIG. 8. It comprises a laser light source 151 with an associated device 152 for narrowing the bandwidth of the laser.
  • An illumination system 153 generates a large, sharply delimited and very homogeneously illuminated image field, which corresponds to the
  • the lighting system 153 has devices for selecting the lighting mode and can be switched, for example, between conventional lighting with a variable degree of coherence, ring field lighting and dipole or quadrupole lighting.
  • a device 154 for holding and manipulating a mask 155 is arranged behind the lighting system in such a way that the mask 155 lies in the image plane 2 of the projection objective 1 and can be moved in this plane for scanning operation.
  • the device 154 comprises the scan drive.
  • Behind the mask plane 2 is the reduction lens 1, which images an image of the mask on a reduced scale on a wafer 156 covered with a photoresist layer, which is arranged in the image plane 4 of the reduction lens 1.
  • the wafer 156 is held by a device 157 that includes a scanner drive to move the wafer in synchronism with the reticle. All systems are controlled by a control unit 158. The structure of such systems and the way they work is known per se and is therefore no longer explained.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

L'invention concerne un objectif de projection catadioptrique qui représente un modèle disposé dans un plan d'objet, par génération d'une image intermédiaire réelle, dans un plan d'image. Cet objectif a, entre le plan d'objet et le plan d'image, une première partie d'objectif catadioptrique, avec un miroir concave et un dispositif de déviation de rayon, derrière lequel se trouve une deuxième partie d'objectif catadioptrique. Ce dispositif de déviation de rayon comporte une première surface de miroir de préférence entièrement réfléchissante pour dévier le rayon provenant du plan d'objet vers le miroir concave. Dans une zone optique proche du plan d'objet, dans laquelle la hauteur du rayon principal du point de champ situé le plus à l'extérieur du rayon provenant de l'objet est supérieure à la hauteur du rayon marginal, un élément de réfringence positive est disposé derrière la première surface de miroir, entre celle-ci et le miroir concave. On obtient ainsi un objectif de projection télécentrique côté objet, qui peut être réalisé avec des dimensions de lentilles relativement faibles et corrigé aisément, si les sollicitations au niveau de l'enduction des surfaces de miroir sont modérées.
PCT/EP2002/008037 2001-12-10 2002-07-19 Objectif catadioptrique Ceased WO2003050587A2 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP02747468A EP1456705A2 (fr) 2001-12-10 2002-07-19 Objectif catadioptrique
JP2003551585A JP2005512151A (ja) 2001-12-10 2002-07-19 カタジオプトリック縮小対物レンズ
AU2002317875A AU2002317875A1 (en) 2001-12-10 2002-07-19 Catadioptrical reduction lens

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US33927501P 2001-12-10 2001-12-10
US60/339,275 2001-12-10

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WO2003050587A2 true WO2003050587A2 (fr) 2003-06-19
WO2003050587A3 WO2003050587A3 (fr) 2003-11-13

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JP (1) JP2005512151A (fr)
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WO (1) WO2003050587A2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6995930B2 (en) 1999-12-29 2006-02-07 Carl Zeiss Smt Ag Catadioptric projection objective with geometric beam splitting
US7218453B2 (en) 2005-02-04 2007-05-15 Carl Zeiss Smt Ag Projection system, in particular for a microlithographic projection exposure apparatus
US7492509B2 (en) 2003-12-02 2009-02-17 Carl Zeiss Smt Ag Projection optical system

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100483174C (zh) * 2004-05-17 2009-04-29 卡尔蔡司Smt股份公司 具有中间图像的反射折射投影物镜
EP1746463A2 (fr) * 2005-07-01 2007-01-24 Carl Zeiss SMT AG Procédé pour corriger un objectif de projection lithographique et un tel objectif de projection
DE102005030839A1 (de) * 2005-07-01 2007-01-11 Carl Zeiss Smt Ag Projektionsbelichtungsanlage mit einer Mehrzahl von Projektionsobjektiven
DE102009037077B3 (de) 2009-08-13 2011-02-17 Carl Zeiss Smt Ag Katadioptrisches Projektionsobjektiv

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5581379A (en) * 1993-02-15 1996-12-03 Omron Corporation Rectangular based convex microlenses surrounded within a frame and method of making
JP3747951B2 (ja) * 1994-11-07 2006-02-22 株式会社ニコン 反射屈折光学系
KR0179138B1 (ko) * 1995-12-01 1999-04-15 구자홍 대물렌즈
EP0838812B1 (fr) * 1996-10-23 2003-04-09 Konica Corporation Procédé d'enregistrement et de reproduction d'un disque optique, lentille d'objectif et méthode de réalisation de cette lentille
EP0989434B1 (fr) * 1998-07-29 2006-11-15 Carl Zeiss SMT AG Système catadioptrique et appareil d'exposition lumineuse utilisante ce système
JP3967851B2 (ja) * 1999-08-11 2007-08-29 フジノン株式会社 フライアイレンズの位置決め構造
US7301605B2 (en) * 2000-03-03 2007-11-27 Nikon Corporation Projection exposure apparatus and method, catadioptric optical system and manufacturing method of devices
JP4116224B2 (ja) * 2000-03-23 2008-07-09 ローム株式会社 レンズアレイの製造方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6995930B2 (en) 1999-12-29 2006-02-07 Carl Zeiss Smt Ag Catadioptric projection objective with geometric beam splitting
US7426082B2 (en) 1999-12-29 2008-09-16 Carl Zeiss Smt Ag Catadioptric projection objective with geometric beam splitting
US7492509B2 (en) 2003-12-02 2009-02-17 Carl Zeiss Smt Ag Projection optical system
US7218453B2 (en) 2005-02-04 2007-05-15 Carl Zeiss Smt Ag Projection system, in particular for a microlithographic projection exposure apparatus

Also Published As

Publication number Publication date
AU2002317875A8 (en) 2003-06-23
WO2003050587A3 (fr) 2003-11-13
JP2005512151A (ja) 2005-04-28
AU2002317875A1 (en) 2003-06-23
EP1456705A2 (fr) 2004-09-15

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