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Catadioptric optical system with diffractive optical element
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a catadioptric optical system for imaging a pattern arranged in an object surface of the optical system into an image surface of the optical system. In a preferred field of application, the opti- cal system is designed as a projection objective suitable for microlitho- graphy, particularly for immersion lithography at image-side numerical apertures NA>1.
Description of the Related Art -
Catadioptric projection objectives are, for example, employed in projection exposure systems, in particular wafer scanners or wafer steppers, used for fabricating semiconductor devices and other types of microdevices and serve to project patterns on photomasks or reticles, hereinafter referred to generically as "masks" or "reticles," onto an object having a photosensitive coating with ultrahigh resolution on a reduced scale.
In order to create even finer structures, it is sought to both increase the image-end numerical aperture (NA) of the projection objective and employ shorter wavelengths, preferably ultraviolet radiation with wavelengths less than about 260 nm. However, there are very few materials, in particular, synthetic quartz glass (fused silica) and crystalline fluorides, that are sufficiently transparent in that wavelength region available for fabricating the transparent optical elements. Since the Abbe numbers of those materials lie rather close to one another, it is difficult to provide purely refractive systems that are sufficiently well color-corrected (cor- rected for chromatic aberrations).
In optical lithography, high resolution and good correction status have to be obtained for a relatively large, virtually planar image field. It has been pointed out that the most difficult requirement that one can ask of any * optical design is that it should have a flat image, especially if it is an all- refractive design. Providing a flat image requires opposing lens powers and that leads to stronger lenses, more system length, larger system glass mass, and larger higher-order image aberrations that result from the stronger lens curvatures. Conventional means for flattening the im- age field, i.e. for correctings the Petzval sum in projection objectives for microlithography are discussed in the article "New lenses for microlitho- graphy" by E. Glatzel, SPIE Vol. 237 (1980), pp. 310-320.
Patent applications US 2002/0005938 Al or US 2004/0119962 Al dis- close purely refractive (dioptric) projection objectives designed for microlithography using ultraviolet radiation employing a set of two diffractive optical elements in combination with negative refractive power between the diffractive optical elements to perform correction of chromatic aberrations and to facilitate correction of image curvature aberration, i.e. cor- rection of Petzval sum. It is pointed out that the effect of diffractive opti- cal power on chromatic aberrations is opposite to the effect of normal dioptric optical power, such as provided by lenses and that, therefore, by mixing dioptric optical power and diffractive optical power chromatic ab- errations can be corrected. Further, since the optical power of a diffrac- tive optical element can be set to predetermined value without making a contribution to image curvature, the correction of the Petzval sum is considerably eased.
Catadioptric projection objectives employing dioptric imaging Subsys- tems including diffractive optical elements are disclosed in US 6,829,099 B2.
Diffractive optical elements capable of being used for correcting colour aberrations in optical systems designed for ultraviolet radiation are also disclosed in US 6,728,036 B2. Obscured catadioptric optical systems employing a diffractive optical element are disclosed in US 5,986,995 and US 5,742,431.
Concave mirrors have also been used for some time to help solve prob- lems of color correction and image flattening. A concave mirror has posi- tive power, like a positive lens, but the opposite sign of Petzval curva- ture. Also, concave mirrors do not introduce color problems. Therefore, catadioptric systems that combine refracting and reflecting elements, particularly lenses and concave mirrors, are often employed for configuring high-resolution projection objectives of the aforementioned type.
One type of catadioptric group frequently used in projection objectives for microlithography is a combination of a concave mirror arranged close to or at a pupil surface and one or more negative lenses arranged ahead of the concave mirror and passed twice by radiation. The Petzval sum of this type of catadioptric group can be varied by changing the refractive power of the lenses and the concave mirror while maintaining an essentially constant refractive power of the entire catadioptric group.
This is one fundamental feature of the Schupmann.-Achromat, which is utilized in some types of catadioptric projection objectives, for example those using geometrical beam splitting with one or more planar folding mirrors for guiding radiation towards the catadioptric group and/or for deflecting radiation emanating from the catadioptric group.
Representative examples for folded catadioptric projection objectives using planar folding mirrors in combination with a single catadioptric group as described above are given in US 2003/0234912 Al or US 2004/01 60677 Al.
International patent application WO 2005/040890 by the applicant discloses catadioptric projection objectives for microlithography employing a first and a second catadioptric subgroup, each with a concave mirror and at least one negative lens element, which contributes to both Petzval and axial colour aberration control. When compared to designs having only a single catadioptric group as mentioned above, this construction allows a comparabily relaxed design of the catadioptric groups and allows for a full correction of axial colour in addition to a full Petzval correction.
If an optical system is sufficiently corrected for chromatic aberrations, light sources with larger bandwidth can be used, particularly laser light sources without devices limiting the bandWidth. At 193 nm operating wavelength ArF excimer lasers including a bandwidth narrowing modul are typically used as a light source providing a bandwidth on the order of 0.1 pm. Optical designs having a correction of the axial chromatic aberration (CHL) typically in the order of 100 - 150 nm/pm are generally sufficient in that case to provide imaging with acceptable contrast. Improving colour correction of an optical design could allow to use light sources having a larger bandwidth, e.g. laser light sources having bandwidth I pm or above, whereby the laser efficiency actually utilized for a printing process could be increased while at the same time the costs for a light source could be decreased.
A stronger correction for chromatic aberrations is desireable for smaller wavelength, such as 157 nm, since laser light sources presently available for that wavelength range do typically not include a bandwidth narrowing device so that the natural bandwidth of the laser, about 1 pm, is used. Further, as the dispersion of calcium fluoride (CaF2) and other fluoride materials sufficiently transparent at wavelength below 193 nm increases as the wavelength decreases, additional measures to correct chromatic aberrations are desired. However, this is difficult for optical designs having a catadioptric group mentioned above for the following reasons.
A catadioptric group including a concave mirror and negative refractive power ahead of that mirror contributes to correction of chromatic aberrations and Petzval sum. Basically, the Petzval correction is achieved by the curvature of the concave mirror and supported by negative lenses in its vicinity. The contribution to Petzval sum correction is directly propor- tional to the curvature hR of the concave mirror, where R, is the curva- ture radius. If the catadioptric group can be designed to provide strong correction of Petzval sum, lenses having strong positive refractive power can be use in other parts of the optical system, thereby allowing a com- pact design characterized by small lens diameters and/or small overall track length of the design. For that reason, a concave mirror having strong curvature and a small diameter would generally be desireable.
On the other hand, negative refractive power close to the concave mirror contributes strongly to chromatic correction, particularly to correction of axial chromatic aberration (CHL). This correction is directly proportional to the square of the marginal ray height (which, close to a pupil position, essentially corresponds to the optically free lens radius) , the refractive power of the lens and the dispersion of the material: Therefore, in order to provide a strong contribution to colour correction, it is desireable to have negative lenses at positions with large marginal ray heights in the catadioptric group. This requirement, however, is opposed to the above requirement for a small sized concave mirror with strong curvature.
Therefore ist appears that chromatic correction of catadioptric optical systems including a concave mirror, particularly in combination with negative refravtive power adjacent to the concave mirror, is difficult to obtain.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a catadioptnc optical system designed for ultraviolet radiation at operating wavelength A < 380 nm which is sufficiently corrected for chromatic aberrations such that imaging with sufficient contrast is possible with radiation from a radiation source having a band width in the order of 1 pm if an excimer laser is used or in the order of 30 nm if a light emitting diode (LED) is used. It is another object to provide a catadioptric optical system for ultraviolet ra- diation at operating wavelength A. < 380 nm which is corrected substan- tially for axial chromatic aberration CHL and lateral chromatic aberration CHV.
As a solution to these and other objects the invention, according to one formulation, provides a catadioptric optical system for imaging a pattern arranged in an object surface of the optical system into an image surface of the optical system using ultraviolet radiation at an operating wavelength A < 380 nm comprising: a plurality of optical elements arranged along an optical path between the object surface and the image surface, the optical elements including at least one transparent optical element transparent to radiation at the operating wavelength and at least one concave mirror; the optical path having a first section formed between the object surface and the concave mirror and a second section formed between the con- cave mirror and the image surface; a diffractive optical element being arranged in a double-pass region ad- jacent to the concave mirror such that radiation of the first section passes the diffractive optical element in a first direction and radiation in the second section passes the diffractive optical element in a second direction opposite to the first direction.
Providing a diffractive optical element (DOE) in a double-pass region passed twice by the radiation directed at the concave mirror and reflected from the concave mirror allows the diffractive optical element to contribute twice to the correction of chromatic aberrations, particularly axial chromatic aberration. As the contribution of a diffractive optical element to chromatic correction generally increases the smaller the size of the diffractive structure forming the diffractive optical element is, the invention allows to use diffractive optical elements having relatively coarse diffractive structures and still obtain good chromatic correction.
As manufacturing of a diffractive optical element generally becomes easier the larger the typical structural size of the diffractive structure is, manufacturing risks and costs can thereby be reduced. Further, since the contribution of a diffractive optical element to stray light generally increases with decreasing structural size of the diffractive structures, the reduction in stray light generation caused by the diffractive optical ele- ment can be obtained. Further, since the contribution of a diffractive op- tical element to chromatic aberrations generally increases for diffractive optical elements having a high density of diffractive structures in areas corresponding to large marginal ray heights, the size of the diffractive optical element characterized by its diameter, can be kept moderate.
In optical imaging systems at least one pupil surface is formed between the object surface and the image surface. In preferred embodiments the * -8- diffractive optical element is arranged at a pupil surface or optically close to a pupil surface. An axial position of a diffractive optical element "opti- cally close to a pupil surface" may be particularly defined as an axial po- sition where the chief ray height CRH is smaller than the marginal ray height MRH. Preferably, the diffractive optical element is arranged at a position where the condition RHR < 0,5 holds for the ray height ratio RHR = CRH/MRH. If this condition is fulfilled, a strong correcting effect can be obtained with diffractive structures having moderate size.
For the purpose of this application, the term "chief ray" (also known as principal ray) denotes a ray emanating from an outermost field point (farthest away from the optical axis) of the effectively used object field OF and intersecting the optical axis at at least one pupil surface position.
Due to the rotational symmetry of the system the chief ray may be chosen from an equivalent field point, e.g. in the meridional plane. In * projection objectives being essentially telecentric on the object side, the chief ray emanates from the object surface parallel or at a very small angle with respect to the optical axis. The imaging process is further characterized by the trajectory of marginal rays. A "marginal ray" as used herein is a ray running from an axial object field point (on the optical axis) to the edge of an aperture stop AS. That marginal ray may not contribute to image formation due to vignetting when an off-axis effective object field is used. The chief ray and marginal ray are chosen to characterize optical properties of the projection objectives. The respective ray heights, chief ray height CRH and marginal ray height MRH, are the distances between the respective ray and the optical axis measured perpendicular to the optical axis.
In preferred embodiments the concave mirror is arranged optically close to or at a pupil surface of the optical system and the diffractive optical element is arranged optically close to the concave mirror. A position uop..
tically close" to the concave mirror is particularly given if the ray height - -9- ratio RHRCM at the concave mirror and the ray height ratio RHRDOE at the diffractive optical element differ by less than 0,5.
According to one embodiment, the diffractive optical element is formed by a diffractive structure formed on a surface of a substrate of an optical element, where that surface is one out of four optical surfaces closest to the concave mirror.
According to one embodiment, the diffractive optical element is formed by a diffractive structure formed on a substantial planar substrate sur- face of a substrate of an optical element. Manufacturing of the diffractive optical element is thereby facilitated. The essentially planar surface may have a a radius of curvature RDOE according to the condition: -1/500 < l/RDQE < 1/500.
The diffractive optical element may be formed on a surface of a plane parallel plate which, depending on its position and alignment in the optical system, has otherwise no major optical effect. In preferred embodiments the diffractive optical element is formed by a diffractive structure formed on a surface of a transparent lens element having refractive power. With other words, a surface of a lens (negative lens or positive lens) may be structured to form the diffractive optical element. For ex- ample the diffractive optical element may bè formed on one lens surface of a negative meniscus lens. The lens surface having the larger radius of curvature may be used, thereby facilitating manufacturing of the diffractive optical element.
In preferred embodiments the optical system includes a catadioptric group including a concave mirror and at least one negative lens ar- ranged adjacent to the concave mirror in a double-pass-region of the optical system passed twice by radiation, where the diffractive optical element is formed by a diffractive structure formed on a lens surface of the negative lens. The lens surface may be essentially planar.
In many applications it may be sufficient to provide just one diffractive optical element to obtain the desired correcting effect. In other embodiments at least one second diffractive optical element in addition to a first diffractive optical element may be provided.
In catadioptric optical systems according to the invention one or more diffractive optical elements are provided to contribute substantially to correction of chromatic aberrations such that other correcting means conventionally used for that purpose are not necessary. Particularly, it is not necessary to use at least two different transparent materials for the lenses, although this could facilitate chromatic aberration control. In pre- ferred embodiments, all transparent optical elements with an optional exception for three optical elements closest to the image surface are made from the same material. For example, in an optical system design for X = 193 nm, all transparent optical elements may be made of fused silica (Si02). In some cases, it may be desireable to use calcium fluoride instead of silicon dioxide for one or two lenses closest to the image surface in order to avoid problems arising from radiation induced density changes in the optical material (particularly compaction). These lenses, however, need not be shaped to contribut&to chromatic correction. For designs of smaller operating wavelength, such as ? = 157 nm, all transparent optical elements may be made of one single material, such as calcium fluoride (CaF2), for example.
In practical cases, the diffraction efficiency of a diffractive optical ele- ment will be less than 100 %. Here, the diffraction efficiency is defined as an intensity ratio between radiation incident on the diffractive optical element and diffracted radiation of a predetermined order after interac- tion with the diffractive optical element. As a consequence, stray light may be generated in the optical system which may disturb the quality of the image to be obtained. In preferred embodiments, a field stop is pro- vided at or close to a field surface optically downstream of the diffractive optical element to prevent stray light from being transferred to the image surface. In preferred embodiments, the optical system is designed to create at least one real intermediate image optically downstream of the concave mirror, and a field stop is provided at that intermediate image or in the vicinity thereof.
The previous and other properties can be seen not only in the claims but also in the description and the drawings, wherein individual tharacteristics may be used either alone or in sub-combinations as an embodiment of the invention and in other areas and may individually represent advantageous and patentable embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. I shows a schematic drawing of a projection exposure appa- ratus for immersion lithography equipped with an embodi- ment of a catadioptric projection objective according to the invention; Fig. 2 shows a lens section of a catádioptric reference projection objective of R-C-R type for microlithography at ?=193 nm without diffractive optical element for comparatitive pur- poses; Fig. 3 shows a lens section of an embodiment of a catadioptric immersion objective of R-C-R type for microlithography at X=193 nm comprising a diffractive optical element;
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Fig. 4 shows a lens section of an embodiment of a catadioptric immersion objective of R-C-R type for microlithography at )=157 nm comprising a diffractive optical element.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following description of preferred embodiments of the invention, the term "optical axis" shall refer to a straight line or sequence of straight-line segments passing through the centers of curvature of the optical elements involved. The optical axis is folded by reflective surfaces. In the case of those examples presented here, the object involved is either a mask (reticle) bearing the pattern of an integrated circuit or some other pattern, for example, a grating pattern. In the examples presented here, the image of the object is projected onto a wafer serving as a substrate that is coated with a layer of photoresist, although other types of substrate, such as components of liquid-crystal displays or substrates for optical gratings, are also feasible.
Where appropriate, identical or similar features or feature groups in different embodiments are denoted by similar reference identifications.
Where reference numerals are used, those are increased by 100 or multiples of 100 between embodiments.
Where tables are provided to disclose the specification of a design shown in a figure, the table or tables are designated by the same numbers as the respective figures.
Fig. 1 shows, schematically, a microlithographic projection exposure system in the form of a wafer scanner WSC, which is used for production of large-scale integrated semiconductor components by means of immersion lithography. The projection exposure system WS has an excimer laser LS as the light source, with an operating wavelength of 193 nm, although other operating wavelengths, for example 157 nm or 248 nm, are also possible. A downstream illumination system ILL produces a large, sharply limited, highly homogeneously illuminated illumination field, which is matched to the telecentnc requirements of the down- stream projection objective P0 on its exit plane EP. The illumination system ILL has devices for selection of the illumination mode and, in the example, can be switched between conventional illumination with a variable coherence degree, annular field illumination and dipole or quadrupole illumination.
A device RS (reticle stage) for holding and manipulating a mask M is arranged behind the illumination system in such a way that the mark is located on the object surface OS of the projection objective P0, and can be moved in a scan- ning direction (y direction) on this plane, for scanning purposes.
The plane OS, which is also referred to as the mask plane, is followed by the catadioptric reduction objective P0, which images an image of the mask on a reduced scale of 4:1 on a wafer 10 which is coated with a photoresist layer.
* Other reduction scales, for example 5:1, 10:1 or 100:1 or more, are likewise possible. The wafer W which is used as a light-sensitive substrate, is arranged such that the planar substrate surface SS together with the photoresist layer essentially coincides with the planar image surface IS of the projection objective P0. The wafer is held by a device WS (wafer stage) which comprises a scanner drive in order to move the wafer synchronously with the mask M and parallel to it. The device WS also has manipulators, in order to move the wafer both in the z direction parallel to the optical axis OA of the projection objective and in the x and y directions at right angles to this axis. A tilting device is integrated, and has at least one tilting axis which runs at right angles to the optical axis.
The device WS, which is provided for holding the wafer W, is designed for use for immersion lithography. It has a holding device HD, which can be moved by a scanner drive and whose base has a flat depression or recess for holding the wafer. A flat liquid-tight holder, which is open at the top, for a liquid immersion medium IL is formed by a circumferential rim R, and the immersion medium IL can be introduced into the holder, and can be carried away from it, by devices that are not shown. The height of the rim is designed such that the filled immer- Sian medium completely covers the surface SS of the wafer W, and the exit- side end area of the projection objective PC can be immersed in the immersion liq- uid between the objective exit and the wafer surface while the working distance is set correctly. The entire system is controlled by a central computer unit CPU.
Fig. 2 schematically illustrates a reference projection objective used as a com- parative optical system to demonstrate some properties influenced by the inven- tion. The projection objective 200 is used to image a pattern, which is arranged on its planar object surface OS, of a mask on a reduced scale on its planar im- age surface IS, which is aligned parallel to the object plane, on a reduced scale.
It has a first, refractive objective part OPI, which Images the object field to form a first, real intermediate image 1MM, a second, catadioptric objective part 0P2, which images the first intermediate image to form a second real intermediate image 1M12, and a third, refractive objective part 0P3, which images the second intermediate image on a reduced scale on the image surface 15. The catadiop- tric objective part 0P2 has a concave mirror CM. A first folding mirror FMI is arranged in the vicinity of the first intermediate image, at an angle of 45' to the optical axis OA, such that it reflects the radiation coming from the object plane in the direction of the concave mirror CM. A second folding mirror FM2, whose planar mirror surface is aligned at right angles to the planar mirror surface of the first folding mirror, reflects the radiation coming1from the concave mirror CM in the direction of the image plane IS.
The folding mirrors FMI. FM2 are each located in the optical vicinity of the in- termediate images, so that the light conductance value (etendue) can be kept low. The intermediate images, that is the entire region between the paraxial in- termediate image and the marginal ray intermediate image, are preferably not located on the mirror surfaces, thus resulting in a finite minimum distance be- tween the intermediate image and the mirror surface, so that any faults in the mirror surface, for example scratches or impurities, are not imaged sharply on the image plane.
The folding angles in this exemplary embodiment are exactly 90 . This is advan- tageous for the performance of the mirror layers of the folding mirrors. Deflec- tions by more or less than 900 are also possible, thus resulting in an obliquely positioned horizontal arm (carrying the concave mirror).
All of the imaging objective parts OPI, 0P2, 0P3 have a positive refractive power.
The first objective part OPI comprises two lens groups LGI 1, LGI 2 each with a positive refractive power, between which a possible diaphragm position exists at a first pupil surface P1 positioned where the chief ray CR, which is shown by a bold line, intersects the optical axis OA. The optical axis is folded through 90 at the first folding mirror FMI. The first intermediate image lMll is produced in the * light path immediately downstream from the first folding mirror FMI.
The first intermediate image IMlI acts as an object for the subsequent catadiop- tric objective part 0P2. This objective part is formed by a catadioptric group CG consisting of the concave mirror CM positioned essentially at a second pupil surface P2 and two negative lenses NLI and NL2 positioned immediately ahead of the concave surface of the concave mirror optically close to the sec- ond pupil surface P2 in a region where the ma?ginal ray height MRH is at least twice or three times as large as the chief ray height CRH. Both lens surfaces of the negative meniscus lens NLI closest to the concave mirror have the same sense of curvature at the concave mirror and are spherical. Second negative lens NL2 having asmaller diameter has a concave aspheric surface facing away from the concave mirror and an almost flat surface SI facing the concave mirror at a position where the chief ray height is at most 20 % of the marginal ray height.
The second intermediate image lMl2, which is located optically immediately in front of the second folding mirror FM2, is imaged by the third re- fractive objective part 0P3 on the image surface IS. The refractive ob- jective part 0P3 has a first positive lens group LG3I, a second negative lens group LG32, a third positive lens group LG33 and a fourth positive lens group LG34. An aperture stop AS is positioned at the third pupil sur- face P3 between the positive lens groups LG33 and LG34, where the chief ray CR intercepts the optical axis.
The projection objective 200 is designed as an immersion objective for 2. = 193 nm having an image-side numerical aperture NA 1,25 when used in conjunction with a high index immersion fluid, e.g. pure water, between the exit surface of the objective and the image plane. The size of the rectangular field is 26mm * 5,5mm. Specifications are summarized in Table 2. The leftmost column lists the number of the refractive, reflective, or otherwise designated surface, the second column lists the radius, r, of that surface [mm], the third column lists the distance, d [mm], between that surface and the next surface, a parameter that is referred to as the "thickness" of the optical element, the fourth column lists the material employed for fabricating that optical element, and the fifth column lists the refractive index of that material. The sixth column lists the optically utilizable, clear, semi diameter [mm] of the optical component. A radius r = 0 in a table designates a planar surface (having infinite radius).
A number of optical surfaces in table 2 are aspherical surfaces. Table 2A lists the associated data for those aspherical surfaces, from which the sagitta or rising height p(h) of their surface figures as a function of the height h may be computed employing the following equation: p(h) = [((1/r)h2)I(1 + SQRT(1 - (1 + K)(1/r)2h2))J + Cl. h4 + C2 h6 + ....
where the reciprocal vatue (1/r) of the radius is the curvature of the surface in question at the surface vertex and h is the distance of a point thereon from the optical axis. The sagitta or rising height p(h) thus represents the distance of that point from the vertex of the surface in question, measured along the z-direction, i.e., along the optical axis. The constants K, Cl, C2, etc., are listed in Table 2A.
All lenses of the reference projection objective 200 are made of fused silica. The catadioptric group CG contributes the major part of axial chromatic aberration correction and image curvature correction. The Petzval correction is mainly achieved by the curvature of the concave mirror and negative lenses NLI, NL2 close to the concave mirror, while a major part of the chromatic correction is achieved by the refractive power of the negative lenses NLI, NL2 in front of the concave mirror (effecting predominantely chromatic length aberration CHL). No particular measures have been taken to obtain full chromatic correction. The optical system has the following chromatic aberrations: Axial chromatic aberration (CHL) = - 95 nm/pm, spherochromatism of the marginal ray = nm/pm, resulting in an offset (displacement) of the best focussing plane = - 120 nm/pm. These values are considered to be characteristic of a system not corrected for chromatic aberrations.
Figure 3 shows a projection objective 30d having the same basic construction as the reference objective 200 of Fig. 2. Therefore, rereferenc is made to the description with regard to sequence and types of lens groups within the optical system. The specification is given in tables 3, 3A.
Like in the projection objective 200, all lenses are made of fused silica.
The catadioptric group CG forming the second imaging objective part 0P2 has a concave mirror CM arranged essentially at the second pupil surface P2, a large negative meniscus lens NLI having curved lens sur- faces with the same sense of curvature immediately ahead of the con- cave mirror, and a second negative lens NL2 adjacent to the first nega- tive lens NLI and having an essentially planar first surface Si facing the concave mirror and an aspherical second surface S2 concave towards the folding mirrors FMI, FM2 on the opposite side.
A diffractive optical element DOE represented by a bold dashed-line in Fig. 3 is formed on the substantially planar surface Si of the second negative lens NL2. In this configuration, the diffractive optical element is arranged in a double-pass region adjacent to the concave mirror which is passed twice by the radiation. Therefore, the radiation is influenced twice by the diffractive effect of the same diffractive optical element DOE which is passed a first time in a first direction when radiation is on a first optical path between the object surface OS and the concave mirror CM, and a second time in a second direction opposite to the first direction when radiation has been reflected by the concave mirror and runs from that mirror towards the image surface. The diffractive optical element DOE is arranged optically close to the second pupil surface P2 where the concave mirror is positioned. Specifically, the chief ray height CRH (i.e. the perpendicular distance of the chief ray from the optical axis) is very small compared to the marginal ray height MRH (perpendicular dis- tance between the optical axis and the marginal ray) at the axial position of the diffractive optical element. In this embodiment the ray height ratio RHR = CRH/MRH 0,1 at the diffractive optical element. Also, the mar- ginal ray height at the diffractive optical element is more than 60 % of the marginal ray height at the concave mirror. Under these conditions, a strong effect of the diffractive optical element on chromatic correction can be obtained if the line density of the diffractive optical element is suf- ficiently large. In the embodiment, a maximum line density of 500 lines/mm is provided. Here the line density is a measure for the fineness of the diffractive structure forming the diffractive optical element. Larger maximium line densities generally correspond to finer structures having a stronger diffracting effect.
Specifically, the diffractive surface acting as the diffractive optical ele- ment may be described by a phase function (r) according to: J?(r) = . (HCO1r2 + HCO2r4 + HCO3r6 +** . + HCOr2") wherein HCO are the coefficiences of the phase function. Upon calcula- tion of the optical effect of the diffractive optical element on rays passing the diffractive structure the law of refraction is replaced by a local lattice approximation at a diffraction order m according to: m2d(r) n'sinO = nsrn --- 2,r dr The phase coefficiences (diffractive constants) are given in table 3B.
The diffractive optical element is used in first order and has positive dif- fractive optical power in the following sense: The lens surface carrying the diffractive structure has a certain vertex radius. A diffractive optical power is said to be positive in the considered diffraction order when the paraxial rays of a homocentric light bundle focused about the center of the vertex curvature are diffracted towards the optical axis.
Employing a diffractive optical element in the described position improves substantially the chromatic correction of the design. Specifically, the chromatic length aberration CHL is reduced to CHL 24 nm/pm, the spherochromatism of the marginal ray is reduced to - 173 nm/pm and there is almost no offset of the best focussing plane ( 0 nm/pm). Given these conditions, an essentially complete correction for chromatic aber- rations is obtained. Residual chromatic aberrations limiting the imaging -20 qualities are the spherochromatism and higher orders of the chromatic
magnification difference CHV in the field zone.
The following observations show some characteristic benefits of this approach.
There is no need of a second transparent optical material (in addition to fused silica) to obtain full chromatic correction. Established manufacturing routines for fused silica lenses and a relatively inexpensive, stable material can therefore be used.
A maximum contribution of a diffractive optical element to chromatic correction is obtained if a finely structured diffractive optical element (char- acterised by a high maximum line density) is used in a position of large marginal ray heights. Therefore, a position of a diffractive optical ele- ment optically close to the third pupil surface P3 on the image side and of the projection objective could be desireable. However, as generation of a stray light by the diffractive structures is likely to occur, a diffractive optical element close to the image surface may be problematic due to interference of stray light with the image formation.
Further, manufacturing of a diffractive optical element at least with the techniques presently used becomes moredifficult the larger the size of the diffractive optical element and/or the larger the maximum density of lines on the diffractive optical element becomes. For this reason the po- sition of the DOE is an exemplary compromise between manufacturabil- ity (diameter, maximum line density, flatness or even planeness of the surface) and contribution (double-pass) to axial chromatic aberration control.
The invention obviates these difficulties and provides optical systems having efficient chromatic correction by a diffractive optical element while at the same time the diffractive optical element can be manufactured with established techniques and stray light problems can be limited or avoided. These benefits are brought about by using a diffractice optical element in a double-pass region close to a pupil surface where the concave mirror is positioned. Under these conditions, the diffractive opti- cal element is passed twice by the radiation, whereby a doublecontribution to chromatic aberrations is obtained. Therefore, the necessary maximum line width for achieving a certain amount of chromatic correction and/or the necessary diameter of the diffractive optical element can be reduced when compared to a diffractive optical element having the same optical effect arranged in a single-pass regiDn (a region passed only once by radiation) of the projection objective.
Further, the diffractive structure forming the diffractive optical element is formed on an essentially planar surface of a lens having (negative) refractive power. Under these conditions, no additional optical element is needed in the optical system to provide the diffractive optical element.
Further, since the surface is substantially planar, conventional techniques for forming the diffractive optical element can be used.
Regarding the stray light generated by the diffractive optical element it is to be noted that the projection objective is designed to form an interme- diate image (second intermediate image M2) optically downstream of the last transit of the diffractive optical element in the vicinity of the sec- ond folding mirror FM2. A field stop FS may be provided close to the second intermediate image, for example between the folding mirror and the concave mirror, to mask stray light thereby preventing the substrate in the image surface IS from being irradiated by stray light, whereby the imaging quality, particularly with respect to contrast, can be improved.
The projection objective 400 in Fig. 4 is based on the general construction of the embodiments in Figs 2 and 3, but designed for 157 nm wavelength and NA 1,25. All transparent optical elements are made of cal- cium fluoride. The specification is given in tables 4, 4A, 4B. Characteristic chromatic aberrations are as follows: Axial chromatic aberration (CHL) = 29 nm/pm; Spherochromatism = - 212 nm/pm; offset of the best focal plane = - 65 nm/pm.
It appears that no complete chromatic correction is possible in this configuration using one single diffractive optical element passed twice by radiation. A further improvement can be obtained by additionally taking one or more of the following measures. Firstly, the used diameter of lenses in the region of the third pupil surface (where the aperture stop AS is located) could be decreased. In that case additional measures for correcting monochromatic wavefront errors should be taken. Secondly, a diffractive optical element having larger maximum line density could be used, requiring additional efforts upon manufacturing. Thirdly, if only one diffractive optical element is to be used in the double-pass region, the diffractive optical element might by positioned closer to the concave mir- ror where the marginal ray height is further increased. For example, the DOE may be formed on one of the surfaces of negative meniscus lens NLI. Forming a diffractive optical element on a curved surface, however, makes manufacturing more difficult. On the other hand it might by difficult to provide an essentially planar surface closer to the concave mirror.
Manufacturing difficulties due to the curvature of the substrate surface and/or the size of the diffractive optical element can be overcome if the diffractive optical element is formed as a holographical optical element (HOE). In the embodiments presented here, the essential planar diffractive optical element is designed as a computer generated hologram (CGH). Finally, at least one second diffractive optical element may be provided in addition to the doubly passed diffractive optical element in order to improve colour correction. This will typically result in increased stray light background and reduced overall transmission which may be acceptable in certain applications.
- 23 - The examples show that the invention allows to design optical system where the diffractive optical element has a diffractive structure with less than 800 lines/mm, and where the best focal plane changes along an axial direction of the projection objective by less than 100 nm/pm wave length shift. This indicates that a high efficiency of the diffractive optical element can be obtained without increasing the line density in regions of 800 lines/mm or above, where manufacturing becomes increasingly dif- ficult.
The invention also allows to relax specifications for the illumination side of a projection exposure apparatus, specifically for the laser light sources used therein. ArF excimer lasers presently used for 193 nm operating wavelength typically have a natural bandwidth &. in the order of 500 pm. Therefore, bandwidth narrowing moduls are needed to narrow the bandwidth considerably, e.g. to obtain a bandwidth in the order of 0,2 pm or 0,1 pm. Presently used F2 laser light sources for 157 nm have typical natural bandwidth in the order of 1 pm to 1,2 pm, and it is desire- able to use those light sources without additional bandwidth narrowing moduls. Due to the efficient colour correction in preferred embodiments of the invention laser light sources can be used having a bandwidth considerably larger than conventionally used at the moment, thereby reducing the overall costs for supplying projection exposure systems. A preferred embodiment of a projection exposure apparatus for microlithography includes: a light source for providing an operating wavelength A < 200 nm at a bandwidth in the region 0,5 pm <tA 5 pm; an illumination system for receiving light from the light source and for illuminating a pattern arranged in an object surface of a projection objec- tive; and a projection objective for imaging a pattern arranged in the object surface into an image surface of the projection objective; - -24- wherein the projection objective includes at least one diffractive optical element.
Preferably, the light source has a bandwidth 0,5 pm = A = 2 pm.
The projection objective may be a catadioptric projection objective having at least one dioptric imaging subsystem and at least one catoptric or catadioptric imaging subsystem including at least one concave mirror, where a diffractive optical element is positioned within the catadioptric or catoptric imaging subsystem.
More preferably, the projection objective includes: a plurality of optical elements arranged along an optical path between the object surface and the image surface, the optical elements including at least one transparent optical element transparent to radiation at the operating wavelength and at least one concave mirror; the optical path having a first section formed between the object surface and the concave mirror and a second section formed between the con- cave mirror and the image surface; a diffractive optical element being arranged in a double-pass region adjacent to the concave mirror such that radiation of the first section passes the diffractive optical element in a first direction and radiation in the second section passes the diffractive optical element in a second direction opposite to the first direction.
According to another aspect of the invention it is proposed that a light source comprising at least one diode emitting UV radiation (i.e. at least one light-emitting diode (LED) and/or at least one laser diode) can be used in a projection exposure apparatus. Specifically, LEDs emitting in the ultraviolet range at < 380 nm appear suitable for that purpose.
More specifically, LED5 having a peak wavelength at about 365 nm (i- line) or 350 nm may be used. Use of diodes emitting UV radiation in a light source may be advantageous for their high life time, allowing con- tinuous operation for a number of years, high quantum efficiency, low maintenance costs and virtually no intensity variations between subse- quent light pulses, for example. However, one drawback is a relatively large bandwidth &, which may be in the order of 30 nm at about A = 360 nm. Generally, the bandwidth decreases as the wavelength be- comes shorter. In order to exploit the advantages of light-emitting diodes or laser diodes for microlithography without suffering from the specific drawbacks of diode UV light sources, projection objectives with high effi- ciency for colour correction according to the invention may be used.
Therefore, the invention also relates to a projection exposure apparatus for microlithography comprising: a light source including at least on diode emitting UV radiation for provid- ing an operating wavelength A <380 nm at a bandwidth EA =30 nm; an illumination system for receiving light from the light source and for illuminating a pattern arranged in an object surface of a projection objec- tive; and a projection objective for imaging a pattern arranged in the object sur- face into an image surface of the projection objective; wherein the projection objective includes at least one diffractive optical element.
The invention has been explained in detail using R-C-R type catadioptric projection objectives with geometrical beam splitting having, in that order between object surface and image surface, a refractive (R) first imaging objective part for creating the first intermediate image, a catadioptric (C) second imaging subsystem for forming a second intermediate image, and a refractive (R) third objective part for imaging the second interme- diate image onto the image surface at a reduced magnification. This se- quence of concatenated optical imaging subsystems can be used in various folding geometries, as exemplified e.g. in US 2004/0233405 Al.
Alternatively, or in addition, this type of R-C-R sytems may be equipped 26 - with one or more diffractive optical elements, e.g. close to or at a pupil position closest to the image plane within a final refractive imaging sub- system. The invention can also be used in other catadioptric optical sys- tems having only one single concave mirror, such as those shown e.g. in US 2004/0160677 Al. Further, catadioptric optical systems having more than one concave mirror, e.g. cross-shape catadioptric systems of type R- C-C-R as shown in WO 2005/040890 may also be equipped with at least one diffractive optical element, preferably positioned in a doublepass region ahead of a concave mirror. The invention may also be used in catadiopric optical systems having a physical beam splitter, such as a polarization-selective polarization beam splitter.
The above description of the preferred embodiments has been given by way of example. From the disclosure given, those skilled in the art will not only understand the present invention and its attendant advantages, but will also find apparent various changes and modifications to the structures and methods disclosed, It is sought, therefore, to cover all changes and modifications as fall within the spirit and scope of the invention, as defined by the appended claims, and equivalents thereof.
The contents of all the claims is made part of this description by reference. -27 -
Table 2 (j398p)
NA = 1,25; field size at wafer: 26 mm * 5,5 mm; wavelength 193 nm SURF RADIUS THICKNESS MATERIAL INDEX SEMIDIAM.
0 0,000000 66,023604 61,0 1 3199,255678 20,752535S102 1,560491 86,1 2 -382,647148 0,999905 88,1 3 148,380198 31,864481 S102 1,560491 95,7 4 393,700243 62,136057 93,9 186,038331 34,951784SI02 1,560491 84,1 6 -364,014035 8,369313 81,3 7 87,427206 49,999849 S102 1.560491 63,8 8 91,904102 25,103092 42,6 9 -94,206062 50,000053 S102 1.560491 41,1 -78,183543 7,767236 58,4 11 -72,911946 37,879804S102 1,560491 59,5 12 -386,680792 20,397697 89,5 13 -388,101203 55,342992S102 1,560491 102,8 14 -124,409055 1,269318 108,5 -368,714756 31,921808S102 1,560491 115,5 16 -182,474520 0,999594 117,9 17 284,855800 32,543287SI02 1,560491 115,7 18 9812,086523 13,050190 114,2 19 223,691268 32,857905S102 1,560491 106,0 9072,588796 69,999906 102,9 21 0,000000 -214,027857 REFL 187,3 22 97,443861 -12,500000SI02 1,560491 74,9 23 945,763333 -53,842423 88,1 24 109,436557 -12,500000S102 1,560491 93,4 200,167657 -26,567640 116,1 26 154,888278 26,567640 REFL 122,4 27 200,167657 12,500000S102 1,560491 116,1 28 109.436557 53,842423 93,4 29 945,763333 12,500000S102 1,560491 88,1 97,443861 214,031 560 74,9 31 0,000000 -69,999716 REFL 182,3 32 1390,655555 -28,616867S102 1,560491 101,6 33 244,690384 -0,999653 104,7 34 -510,795683 -31,609961S102 1,560491 112,7 623,955672 -0,999734 113,4 36 -238,131388 -36,493887S102 1,560491 114,1 37 -23913,292182 -1,527160 112,5 38 -143,046352 -41,147020S102 1,560491 102,4 39 -565,969735 -18,182633 97,8 905,328362 -11,417867S102 1,560491 95,0 41 -102,899107 -55,951031 79,2 42 -658,743127 -12,613394SI02 1,560491 82,0 43 -117,304120 -42,613598 82,8 44 -436,636633 -22,474028SI02 1,560491 97,2 * -282116,661939.73,100014 99,4 46 6947,652827 -17,850956S102 1,560491 122,3 47 553,388986 -1.838671 125,6 48 -420,085562 -23,334910S102 1,560491 138,0 49 -1033,498054 -2,951 440 138,7 -347,234369 -45,123736S102 1,560491 143,0 51 929,353280 -9,717158 142,5 52 0,000000 8,713732 138,5 53 -643,673924 -44,029995 S102 1,560491 141,9 54 518,206647 -1,000059 141,5 -285,072352 -42,041724S102 1,560491 130,0 56 3469,578294 -6,917218 126,7 57 -124,759465 -30,000115S102 1,560491 96,7 58 -173,984389 -1,259869 89,2 59 -96,014715 -31,773179S102 1,560491 77,1 -208,095441 -1,101361 67,2 61 -61,113676 -46,795199S102 1,560491 51,3 62 0,000000 -1,001 571 H20 1,436823 20,0 63 0,000000 0,000000 18,3
- -------
- -29-
Table 2 A
Aspheric Constants SRF 6 15 20 22 30 K 0 0 0 0 0 CI 7,141 270E-08 -1,01 3030E-08 I,582023E-08 -9,996018E-08 -9,99601 8E-08 C2 7,930370E-t 3 3, 530505E-1 3 2,556765E-1 3 -6,0351 05E-1 2 -6,0351 05E-1 2 C3 3,781606E-16 -1,060933E-17 -2,049352E-17 -4,685076E-16 -4,685076E-16 C4 -2,752780E-20 1,225986E-22 6,559560E-22 -3,223767E-20 -3,223767E-20 C5 3,14071 9E-25 6, 609657E-27 -7,430255E-27 -1,292578E-24 -1,292578E-24 C6 3,161 960E-29 -1, 256536E-31 -1,283934E-31 -4,622971 E-28 -4,622971 E-28 SRF 39 41 43 46 51 K 0 0 0 0 0 Cl -1,477442E-08 -3,58021 7E-08 5,723773E-08 321 7956E-08 -7, 721 076E-09 C2 -1,235073E-13 1,459206E-12 4,935219E-12 -6,007934E-15 -3, 693173E-14 C3 8,612853E-1 7 -1,137144E-1 6 2,208353E-1 6 -1,372354E-1 8 2,487685E-1 7 C4 -6,948562E-21 1,21 0977E-20 1,316781 E-20 -4.458623E-22 9,499004E-22 C5 4,1 80820E-25 1,46501 6E-24 -1,299381 E-24 1,051 732E-26 1,579807E-26 C6 -7,1 83386E-30 -1,06921 8E-28 2,460291 E-28 -5,508656E-3 1 1,044985E-3 1 SRF 58 60 K 0 0 Cl 1,081662E-08 -1,106215E-07 C2 -2, 399129E-12 -1,956390E-1 1 C3 6,061508E-16 I,625686E-1 5 C4 -4,349995E-20 3,032929E-19 C5 -1,348891 E-24 2,937298E-23 C6 1,283369E-28 -1.259904E-27 - 30-
Table 3 (kl2p)
NA = 1,25; field size at wafer:26 mm * 5,5mm; wavelength 193 nm SURF RADIUS THICKNESS MATERIAL INDEX SEMIDIAM.
0 0,000000 60,878983 61,0 1 250,959796 24,381209SI02 1,560491 89,1 2 4340,944288 4063403 89,7 3 143,265225 29,878570S102 1,560491 93,3 4 324,836261 68,486367 91,2 115,929759 32,811033S102 1,560491 76,4 6 1455,781454 1,276869 72,2 7 86,877452 44,995575S102 1,560491 62,6 8 97762384 31,958014 44,0 9 -80,484048 40,055346 S102 1,560491 43,3 -76,540448 6,401389 57,5 11 -73,990741 14,052372 8102 1560491 58,6 12 -143,768888 56,637492 70,6 13 -286,206562 43,0836215102 1,560491 101,1 14 -1 30,058552 0,998442 105,8 -848,745104 32,726586S102 1,560491 112,5 16 -219,628391 0,997606 114,1 17 587,218046 29,610977S102 1,560491 111,9 18 -623,493709 0,996073 111,0 19 195,355935 27,342151 Sf02 1,560491 102,3 553,440732 69,993028 98,8 21 0,000000 -235,603616 REFL 177,6 22 95,594111 -12,500000 Sf02 1,560491 76,6 23 0,000000 -55,160984 90,8 24 108,066787 -12,5000005102 1,560491 94,9 219,797058 -32,667284 120,6 26 162,100828 32,667284REFL 128,9 27 219,797058 12,5000005102 1,560491 120,6 28 108,066787 55,160984 94,9 29 0,000000 12,500000S102 1,560491 92,9 95,594111 235,622863 76,6 31 0,000000 -82,952404 REFL 188,3 32 346,991249 -24,199489 SIO2 1,560491 106,2 33 207,218179 -1,801469 110,1 34 -2094,290075 -31,294191 Sf02 1,560491 119,8 397,124902 -0,997856 121,3 36 -219,676650 -48,325077S102 1,560491 126,1 37 6264,638856 -0,997510 124,5 38 -156,903216 -39,496976 S102 1,560491 111,4 39 -434,308787 -28,802866 107,1 4348,425311 -10,006921 Sf02 1,560491 97,8 41 -125,962612 -81,011665 82,8 42 -1840,539483 -9,997830S102 1,560491 85,7 43 -120,320418 -60,509795 86,5 44 -639,951658 -29,666907S102 1,560491 109,2 560,250687 -33,497524 111,6 46 -2904,572259 -23,762469 S102 1,560491 123,3 47 444,781935 -0.999067 125,7 48 -453,963291 -24.742430 S102 1,560491 133,4 49 -1946,544204 -22,224336 133,6 -438,384650 -30,822035S102 1,560491 136,1 51 1778,034964 -9,198291 135,4 52 0,000000 8,013899 131,7 53 -707,338314 -43,121095S102 1,560491 135,0 54 429,967883 -0,997571 134,8 -279,119843 -41,234378S102 1,560491 123,3 56 1713,281185 -0.992765 120,1 57 -111,007939 -29,779320 S102 1,560491 90,9 58 -142,787540 -0,989514 82,8 59 -98,905879 -29,730854S102 1,560491 74,9 -214,618200 -0,980119 65,1 61 -62,815373 -42,256735StO2 1,560491 49,4 62 0,000000 -1,001571 Water 1,436823 20,0 63 0,000000 0,000000 18,3 - 32 -
Table 3 A
Aspheric Constants SRF 6 15 20 22 30 K 0 0 0 0 0 Cl 6,2191 60E-08 9, 634579E-1 0 1,7991 70E-08 -8,461 259E-08 -8,461 259E-08 C2 8,61 3095E-1 2 -3,467196E-1 3 -3,462448E-1 3 -5,571 008E-1 2 -5,571 008E-1 2 C3 8,79711 OE-1 6 7,377333E-1 8 9,973798E-1 8 -4,39201 3E-1 6 -4,39201 3E-1 6 C4 -4, 336491 E-20 -2,696294E-22 -2,587523E-22 -3,109594E-20 -3,109594E-20 C5 3, 621 376E-24 1,041 070E-26 3,589430E-27 1,600041 E-24 1,600041 E-24 C6 -8, 723735E-30 -2,71 5585E-31 -9,527804E-32 -9,759574E-28 -9,759574E-28 SRF 39 41 43 46 51 K 0 0 0 0 0 Cl -2,401 543E-09 -6,792831 E-08 4,170051 E-08 3,07181 OE-08 -1,408537E-08 C2 1,1 42480E-1 3 -4,315251 E-1 2 5,621 753E1 2 -1,900305E-1 3 8,091 952E-14 C3 -2,21 9092E-1 7 -1,914299E-1 6 1, 673521 E-1 6 7,979932E-1 8 -1,966820E-1 7 C4 1,239492E-21 -1,22891 IE-20 1,785079E-20 -5,966794E-22 8,348551E-22 C5 -4,806457E-26 -1,398652E-24 -1, 539006E-24 3,330212E-26 -1,782051 E-26 C6 8,985848E-31 6,805141 E-30 1, 344065E-28 -1,1 73359E-30 1,555748E-31 SRF 58 60 K 0 0 Cl 1,384135E-08 -7, 154063E-08 C2 -1,329542E-12 -2,304402E-11 C3 5,527717E-16 2,354346E-15 C4 4,295920E-20 -4,048596E-19 C5 -9,263512E-24 3,642365E-23 C6 1,48061 1E-29 5,138032E-27
Table 3 B
Diffractive Constants Diffraction order -1 SRF 23 HCO I 5,7317E-04 HCO 2 4,9550E-09 HCO 3 3,0701E-13 HCO4 -7,2013E-18 - 33 -Table 4 (kl3p)
NA = 1,25; field size at wafer: 26 mm * 5,5 mm; wavelength 157 nm SURF RADIUS THICKNESS MATERIAL INDEX SEMIDIAM.
0 0,000000 61,983286 61,0 1 228,953959 25,381466CAF2 1,5541 22 90,1 2 2075,074583 0,999782 90,6 3 137,627317 30,295924CAF2 1,554122 93,5 4 291,281179 66435918 91,1 108,202615 33,579704CAF2 1,554122 75,3 6 1216,450917 5,158756 70,7 7 88,467206 39,241228CAF2 1,554122 60,3 8 100,149071 30,569122 43,9 9 -76,429556 43,981 661 CAF2 1,554122 42,8 -79,741708 5,680299 59,2 11 -78,741144 10,00002ICAF2 1,554122 60,4 12 -122,702955 71.814825 68,8 13 -260,9941 52 39,809511 CAF2 1,554122 102,9 14 -134,628986 0,999404 107,4 -1268,494402 34,143806CAF2 1,554122 114,0 16 -228,261586 0,999012 115,5 17 464,450313 28,420913CAF2 1,554122 112,6 18 -1108,758555 0,998653 111,4 19 191,140521 28,738533CAF2 1,554122 103,5 548,654567 69,997974 100,0 21 0.000000 -220,201741 REFL 182,3 22 92,146693 -12,500000CAF2 1,554122 73,1 23 0,000000 -60,097945 86,4 24 107,012148 -12,500000CAF2 1,554122 93,3 213,974763 -32,360872 118,9 26 161,085559 32,360872 REFL 127,7 27 213,974763 12,500000CAF2 1,554122 118,9 28 107.012148 60,097945 93,3 29 0,000000 12,500000CAF2.. 1,554122 88,0 92,146693 220,212565 73,1 31 0,000000 -70,292584 REFL 195,1 32 436,427918 -25,679375CAF2 1,554122 104,1 33 212,297807 -4,058922 107,7 34 -1862,389523 -31,182381CAF2 1,554122 117.0 385,558047 -0,999913 118,5 36 -266,455994 -39,306470CAF2 1,554122 121,6 37 4097,712841 -0,999715 120,3 38 -159,672828 -41,174904CAF2 1,554122 111,1 39 -600,884406 -39,082664 107,2 -7390,537902 -9,999759 CAF2 1,554122 91,2 41 -122,961015 -65,115735 78,9 42 1681,135830 -9,999560CAF2 1,554122 81,7 43 -124,352494 -56,643496 84,3 44 -646,100228 -28,946760CAF2 1,554122 107,6 * -34- 557,787358 -35,729940 110.3 46 -2101,138695 -27,025220CAF2 1,554122 123,9 47 401,049814 -7,528398 126,4 48 -482,548933 -24,526528CAF2 1,554122 136,0 49 -2133,358165 -20,474964 136,3 -458,409266 -29,994422 CAF2 1.554122 139,1 51 1790,413690 -15,759284 138,4 52 0,000000 11,215438 134,8 53 -679,430730 -45,473827 CAF2 1,554122 138,0 54 425,742750 -0.997707 137,9 -270,559167 -44,394272CAF2 1,554122 126,1 56 1502,539561 -0,995806 122,8 57 -107,471148 -32,259683CAF2 1,554122 91,0 58 -1 43,601476 -0,994482 82,5 59 -96,541822 -29,108302CAF2 1,554122 73,9 -1 94,667846 -0,987194 63,7 61 -62,707854 -41,252549CAF2 1,554122 49,2 62 0,000000 -1.001 571 IMMERS 1,370000 20,5 63 0,000000 0,000000 18,3 - 35 -
Table4A
Aspheric Constants SRF 6 15 20 22 30 K 0 0 0 0 0 Cl 1,002793E-07 -3, 219237E-09 I,287016E-08 -l,066490E-07 -1,066490E-07 C2 7,034741 E-1 2 -5, 299733E-14 -1,048628E-1 3 -6,428779E-1 2 -6,428779E-1 2 C3 1,1 05573E-1 5 -1,179951 E-18 6,216601 E-20 -5,21 7974E-1 6 -5,21 7974E-1 6 C4 -5, 374624E-20 -6,472838E-23 2,333768E-22 -4,241 729E-20 -4,241 729E-20 C5 4, 835003E-24 6,532593E-27 -2,423138E-26 5,783894E-25 5,783894E-25 C6 4, 482056E-28 -1,714951 E-31 8,509939E-31 -1,4771 82E-27 -1,4771 82E-27 SRF 39 41 43 46 51 K 0 0 0 0 0 Cl -1,098914E-08 -6,314936E-08 4,795158E-08 2, 763474E-08 -1,662913E-08 C2 3,771632E-13 -5,760544E-12 6,633033E-12 -8, 349590E-14 9,819798E-14 C3 -2,378221 E-1 7 -2,947799E-1 6 1,845072E-1 6 6, 731488E-1 8 -1,558385E-1 7 C4 1,023379E-2 1 -2,61 5529E-20 9,71 0892E-21 2,796447E-22 7,231 206E-22 C5 -3,341042E-26 -1,602947E-24 -1,472336E-24 3, 124227E-26 -1,717881E-26 C6 5,500401 E-31 -1,551220E-28 9,095534E-29 -1. 062967E-30 I,631077E-31 SRF 58 60 K 0 0 Cl 3,722662E-10 -8,802590E-08 C2 6,006351E-13 -2,755778E-11 C3 6,891408E-16 2,902572E-15 C4 8,449866E-21 5,415614E-19 C5 -7,845901 E-24 4,016981 E-23 C6 3,174468E-29 7,232174E-27
Table 4 B
Diffractive Constants Diffraction order -1 SRF 23 HCO I 4,5600E-04 HCO 2 1,4152E-09 HCO 3 2,4982E-13 HCO 4 -8,3530E-18 - 36-