# Patent

## Title
Imaging system, in particular for a microlithographic projection exposure apparatus

## Abstract

The invention concerns imaging systems, in particular for a microlithographic projection exposure apparatus, for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system. An imaging system according to the invention comprises: an object plane-side subsystem which produces a first intermediate image with an object plane-side imaging scale βo, at least one further subsystem which produces a further intermediate image between the first intermediate image and the image plane, and an image plane-side subsystem which images the further intermediate image into the image plane with an image plane-side imaging scale βi, wherein the condition 0.75≦βo*βi≦1.25 is satisfied.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns an imaging system and in particular a projection objective of a microlithographic projection exposure apparatus.
2. State of the Art
Microlithography is used for the production of microstructured components such as for example integrated circuits or LCDs. The microlithography process is carried out in what is known as a projection exposure apparatus comprising an illumination system and a projection objective. The image of a mask (=reticule) illuminated by means of the illumination system is in that case projected by means of the projection objective on to a substrate (for example a silicon wafer) which is coated with a photosensitive layer (photoresist) and which is arranged in the image plane of the projection objective, in order to transfer the mask structure on to the photosensitive coating of the substrate.
Particularly in the early days of microlithography, so-called ‘copy systems’ with an imaging scale β of close to 1 were used as the projection objectives. Designs by way of example of such ‘copy systems’ are set forth hereinafter without laying any claim to completeness and without a definitive appreciation thereof, as state of the art.
JP 2003185923 A discloses such a projection objective which is designed for a working wavelength of 365 nm and which has two catadioptric subsystems K1 and K3 with mutually displaced optical axes, between which an intermediate image is produced. Each of the subobjectives has a concave mirror for correction of image field curvature and a polarisation beam splitter for folding of the optical axis.
JP 2004086110 A discloses a purely refractive projection objective PL which is also designed for a working wavelength of 365 nm and between the lens groups G1 and G2 of which no intermediate image is produced and for which a numerical aperture of NA=0.275 is specified.
In order to do justice to the demands on manufacture of ever smaller structures in the μm range, present projection objectives for microlithography are typically designed in the form of reduction objectives with an imaging scale β of less than 1 and typically β=0.25 or less (for example with β=0.125, β=0.100 etc). That also reduces in particular the demands on the microstructuring of the mask (which depending on the above-mentioned imaging scale is 4 times, 8 times, 10 times etc larger). In order to correct the aberrations which occur in particular in such projection objectives which are of an ever more complex structure, high-resolution reduction objectives typically have a relatively large number of for example 20 or more optical elements such as lenses, mirrors, prisms and so forth.
Catadioptric designs which have both refractive and also reflecting components are particularly wide-spread. Admittedly, in such projection objectives, it is possible to achieve relatively high numerical apertures which can be further increased by means of immersion lithography to values above 1, but the process complication and expenditure in terms of production and adjustment is considerable in regard to the large number of different optical elements which are to be adjusted as precisely as possible relative to each other.
Furthermore, aspheric members are also used in the correction of aberrations, whereby further degrees of freedom are introduced in the optical system in particular without additional lens elements. In that respect it is known in particular that the position of aspherical surfaces in the system substantially influences the mode of action thereof on different kinds of aberration. An inventory of the ranges of action of aspheric members in dependence on the height of the outermost ray emanating from the object center beam and of the main ray is to be found for example in W Besenmatter: ‘Analyse der primären Wirkung asphärischer Flächen mit Hilfe des Delano-Diagramms’, [‘Analysis of the primary action of aspherical surfaces by means of the Delano diagram’], OPTIK, Vol 51, No 4, 1978, pages 385-396.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an alternative design of an imaging system, in particular for a microlithographic projection exposure apparatus, which on the one hand is of a structure which is of utmost simplicity and which is advantageous in terms of production engineering and which on the other hand permits the achievement of relatively high levels of resolution.
That object is attained by the features of the independent claims.
In accordance with the invention an imaging system for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system, comprises
an object plane-side subsystem which produces a first intermediate image with an object plane-side imaging scale βo;
at least one further subsystem which produces a further intermediate image between the first intermediate image and the image plane; and
an image plane-side subsystem which images the further intermediate image into the image plane with an image plane-side imaging scale βi;
wherein the condition 0.75≦βo*βi≦1.25 is satisfied.
The arrangement according to the invention, in regard to the object plane-side subsystem and the image plane-side subsystem, provides a structure which is mirror image symmetrical substantially (that is to say in the specified limits), in which respect the expression mirror image symmetrical is related to a pupil plane or aperture plane of the imaging system. That symmetry (in the case of a totally symmetrical structure) or ‘quasi-symmetry’ (in the case of a structure which is approximately symmetrical in accordance with the invention) has the result that substantially similar or even identical optical elements (in particular lenses, mirrors or prisms) can be used in said subsystems, which considerably reduces the complication and expenditure in manufacturing procedure.
At the same time the production of the at least one further intermediate image (and thus the presence of a total of at least two intermediate images in the entire imaging system) permits a structure with effective correction of image field curvature (‘Petzval correction’). That is the case in particular because, in the proximity of said intermediate images, because of the beam diameter being comparatively small there, it is possible to achieve effective division or splitting of the beams, which lead to an optical element which is used for the correction of image field curvature such as for example a concave mirror or are reflected by same. That in turn permits the production of even larger image fields with a relatively slight image field curvature (in particular practically ‘flat’ image fields) and high levels of resolution.
A further advantage achieved by the symmetry or ‘quasi-symmetry’ according to the invention is that it is already for reasons of symmetry that certain aberrations such as coma or distortion errors can be almost ideally compensated in a simple manner and without the use of further optical correction elements.
In the copy systems presented in accordance with this application, with an overall imaging scale of the imaging system at least close to 1, it is possible to produce comparatively large image fields, which has for example advantages in terms of a simpler and easier scan process, which is to be controlled with fewer adaptation procedures, in wafer production.
In addition, because of the comparatively large image fields which can be achieved (of for example more than 30 mm, in particular about 100 mm), the present invention can be used to good effect in the production of LCD arrangements or FPD arrangements (FPD=flat panel display).
Furthermore the invention can advantageously be used for what is referred to as ‘wafer level packaging’ in which the entire structure and connecting technology is integrated with wiring of the chips (referred to as ‘dies’) into the lithography process, in which case the contacts are applied to the entire underside of the devices, that is to say distributed over the entire area. Typically in wafer level packaging, with minimum structure sizes which are less by one to two orders of magnitude in comparison with the IC production process, comparatively large areas (for example two to four chips of a size of 26 mm*33 mm) are exposed in one step (that is to say in what is to referred to as the step-and-repeat mode). The present invention is therefore advantageous in regard to those uses because of the large image fields which can be achieved according to the invention.
In accordance with a preferred embodiment in the imaging system according to the invention for the object plane-side imaging scale and the image plane-side imaging scale the condition 0.85≦βo*βi≦1.15, preferably 0.95≦βo*βi≦1.05, still more preferably βo*βi=1 is fulfilled.
In addition for a total imaging scale β preferably the condition 0.75≦β≦1.25, preferably 0.85≦β≦1.15, further preferably 0.95≦β≦1.05 and still more preferably β=1 is fulfilled.
In accordance with a preferred embodiment the further subsystem has at least one concave mirror.
In accordance with a preferred embodiment the imaging system according to the invention is substantially telecentric at the object plane side and/or the image plane side. Particularly preferably the imaging system is therefore telecentric at the object plane side and the image plane side (referred to for brevity as ‘two-sided’ or ‘doubled’ telecentric). This means that the entry pupil (in the case of object plane-side telecentry) or the exit pupil (in the case of image plane-side telecentry) or both (in the case of doubled telecentry) are ‘at infinity’, that is to say therefore the respective principal rays extend parallel to the optical axis. That configuration has the advantage that, even in the case of an imaging system which is not precisely set (with object or image surfaces which are not arranged exactly in the object or image planes respectively for example as a consequence of adjustment errors), the imaging is admittedly out-of-focus but is nonetheless true to scale. For example lines which are to be imaged are admittedly shown out-of-focus as a consequence of the focus error in the image plane, but nonetheless are at the correct positions (both relative to each other and also relative to the overall imaging system), which is of particularly great significance precisely when imaging microstructures.
In accordance with a preferred embodiment all subsystems are arranged on a common optical axis.
In accordance with a preferred embodiment the object plane and the image plane are arranged in mutually parallel relationship.
In accordance with a preferred embodiment the further subsystem forms the first intermediate image in the second intermediate image.
In accordance with a preferred embodiment the image-side numerical aperture (NA) is greater than 0.6, preferably greater than 0.8, still more preferably greater than 1.0.
In accordance with a preferred embodiment the imaging system is of substantially mirror image symmetrical configuration in relation to a pupil plane of the imaging system.
In accordance with a preferred embodiment the imaging system produces in the image plane an image field of a diameter of at least 30 mm, preferably at least 50 mm, still more preferably at least 100 mm.
In accordance with a further aspect of the invention an imaging system for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system, comprises
a first dioptric group in front of a pupil plane of overall positive refractive power; and
at least one second dioptric group after a pupil plane of overall positive refractive power;
wherein the imaging system has an imaging scale β′, for which the condition 0.50≦β′≦1.50 is fulfilled;
wherein the imaging system is of a telecentric configuration at the object plane side and the image plane side; and
wherein there is provided at least one aspheric lens surface for which the condition |sin σmax/sin σo|>0.4 is fulfilled, wherein σmax gives the maximum angle of inclination of the rays which emanate from said lens surface to the next lens surface and wherein σo gives the angle of inclination of that edge ray which emanates from the object point on the optical axis to the optical axis.
That configuration provides that particularly effective correction of aberration phenomena is achieved in the symmetrical or quasi-symmetrical systems according to the invention, in which respect in particular account is firstly taken of the fact that, in such symmetrical and quasi-symmetrical systems, the uneven aberrations such as distortion, coma and CHV (=chromatic magnification difference) are compensated internally between the lens groups in front of the plane of symmetry and the lens groups after the plane of symmetry and only the other aberrations are to be corrected. Those remaining aberrations involve in particular SA (=spherical aberration), AST (=astigmatism) and PTZ (=image field or Petzval curvature) of low and high orders.
In principle the aberrations which are rather difficult to correct can be subdivided into two categories:
A first category of aberrations which are heavily dependent on the field and weakly dependent on the aperture, includes AST and PTZ of higher order (low-order PTZ is corrected either with mirrors, see FIG. 5, or with negative lens groups, see FIGS. 7 through 9). Aspheric members are suitable for influencing the aberrations of this first category in regions where the height of the principle ray which emanates from the object point at the maximum spacing relative to the optical axis is great, but the height of the edge ray which emanates from the object point on the optical axis is not zero.
A second category of aberrations which are heavily dependent on aperture and weakly dependent on the field includes in particular oblique spherical aberration. Aspheric members are suitable for influencing the aberrations of that second category in regions where the height of the edge ray which emanates from the object point on the optical axis is great but the height of the principal ray which emanates from the object point at maximum spacing relative to the optical axis is not zero.
The above-indicated regions are thus respective zones involving divergent or convergent beams which in the imaging system are arranged at positions of relatively small optically free diameter (that is to say in front or after positions of maximum optical free diameter). By virtue of the fact that, in accordance with the invention, there is provided at least one aspheric lens surface for which the condition |sin σ/sin σo|>0.4 is fulfilled, the aspheric member or members in question are specifically inserted in those zones with divergent or convergent beams so that this provides correction of aberrations which is matched targetedly at the factors involved in the symmetrical or quasi-symmetrical systems according to the invention and which is thus particularly effective.
For the imaging scale β′ preferably the condition 0.80≦β′≦1.20, still more preferably β′=1, is fulfilled.
In accordance with a further preferred embodiment the image-side numerical aperture (NA) is greater than 0.30, preferably greater than 0.40 and still more preferably greater than 0.60.
In accordance with a preferred embodiment an intermediate space between the image plane-side last optical element and the image plane and/or an intermediate space between the object plane-side last optical element and the object plane is filled with an immersion medium which has a refractive index of greater than one.
In accordance with a preferred embodiment the imaging system according to the invention is designed for a wavelength of 248 nm, in particular 193 nm, further particularly 157 nm.
Particularly for use for wafer level packaging, the imaging system of the invention, in accordance with a further preferred embodiment, is designed for at least one of the wavelengths 436 nm, 405 nm and 365 nm (g-, h- and i-lines in the spectrum of the mercury vapor lamp).
In accordance with a further aspect the invention concerns a microlithographic projection exposure apparatus, a process for the microlithographic production of microstructured devices, a process for wafer level packaging, a microstructured device, an LCD arrangement and a flat panel display.
Further configurations of the invention are set forth in the description hereinafter and the appendant claims.
The invention is described in greater detail hereinafter by means of embodiments by way of example illustrated in the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1a)-c) show schematic system diagrams to illustrate the structure in principle of an imaging system according to the invention in accordance with a first embodiment of the invention, which is of a catadioptric design,
FIGS. 2a)-i) show diagrammatic partial views of different modifications of the structure in principle of FIG. 1,
FIG. 3a)-c) show schematic system diagrams to illustrate the structure in principle of an imaging system according to the invention in accordance with a further embodiment of the invention, which is of a catadioptric design,
FIG. 4a)-c) show schematic system diagrams to illustrate the structure in principle of an imaging system according to the invention in accordance with a further embodiment of the invention, which is of a catadioptric design,
FIG. 5 shows a meridional overall section through a complete catadioptric projection objective in accordance with an actual embodiment of the invention,
FIG. 6 shows a schematic system diagram to illustrate the structure in principle of an imaging system according to the invention in accordance with a further embodiment of the invention, which is of a purely refractive design,
FIGS. 7-9 each show a meridional overall section through a complete projection objective of a purely refractive design in accordance with further actual embodiments of the invention,
FIGS. 10-13 each show a respective diagram in which, for each of the optical surfaces of the projection objectives of FIG. 5 and FIGS. 7-9 respectively (in accordance with the surface number plotted on the horizontal axis), the associated value for sin(σmax/sin(σo) is represented by the bar height in the diagram, and
FIG. 14 shows the diagrammatic structure of a microlithography projection exposure apparatus.



DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1 the structure in principle of a catadioptric imaging system 100 in accordance with a first embodiment of the present invention is illustrated therein. The imaging system 100 has a first optical subsystem 110, a second optical subsystem 120 and a third optical subsystem 130.
In the sense of the present application, the term ‘subsystem’ always denotes such an arrangement of optical elements, by which a real object is represented in a real image or intermediate image. In other words, each subsystem starting from a given object or intermediate image plane always includes all optical elements to the next real image or intermediate image.
Furthermore, in the sense of the present application, the term ‘optical axis’ denotes a respective straight line or a succession of straight line portions, which extends through the center points of curvature of the respective optical components.
Furthermore, in the sense of the present application, the term ‘imaging scale’ of a subsystem denotes the ratio of the magnitude of the image field produced by the subsystem from a given object field relative to the magnitude of the respective object field.
In accordance with the foregoing definitions the optical subsystem 110 includes along the optical axis a first positive lens group 111, a second positive lens group 112, a third negative lens group 113 and a fourth positive lens group 114, downstream of which is produced a first intermediate image IMI1. Arranged in the beam path downstream of the first intermediate image IMI1 is a double folding mirror 121 having two mirror surfaces 122 and 123 disposed at an angle relative to each other, in such a way that incoming light from the lens group 114 is firstly reflected at the mirror surface 122 in the direction of a positive lens group 124a, a negative lens group 124b and a subsequent concave mirror 125. The light reflected at the concave mirror 125, after again passing through the negative lens group 124b and the positive lens group 124a, is reflected at the second mirror surface 1213 of the double folding mirror 121 so that the optical axis OA is as a result folded twice through 90°. The subsystem 120 produces a second intermediate image IM2 and the light emanating therefrom then impinges on the third optical subsystem 130 which comprises a first positive lens group 131, a second negative group 132, a third positive lens group 133 and a fourth positive lens group 134. The second intermediate image IM2 is produced on the image plane ‘IP’ by the third optical subsystem 130.
The concave mirror 125 of the second optical subsystem, in per se known manner, permits effective compensation of the image field curvature produced by the subsystems 110 and 130, wherein the subsystems 110 and 130 can each in themselves be substantially uncorrected in respect of their Petzval sum so that the imaging system 100 produces an image field which in the ideal case is flat, while being of a relatively simple structure.
As can be seen from the diagrammatic sectional views in FIGS. 1b and 1c, it is possible to provide, in adjoining relationship with the object plane OP and/or the image plane IP, an immersion medium 150 or 160 respectively (for example deionised water) with a refractive index n of greater than one, which is then disposed between the object or image plane respectively and an object plane-side or image plane-side last optical element 151 and 161 respectively.
With respect to an axis of symmetry extending through the double folding mirror 121 the imaging system 100 is of a mirror image-symmetrical structure and in particular also of a doubled telecentric structure (that is to say telecentric at the object side and the image side). The imaging scale βo of the first, object plane-side subsystem 110 (which produces the first intermediate image IMI1 which is enlarged in relation to the object field) corresponds precisely to the inverse of the imaging scale βi of the third, image plane-side subsystem 130 (which produces from the second intermediate image IMI2 an image field which is reduced in size in relation thereto).
The relationship βo*βi=1 therefore applies to the imaging system 100. In addition, as can also be seen from FIG. 1, the imaging scale β2 of the second optical subsystem 120 is β2=1 so that the entire imaging system 100 is implemented with an imaging scale βo*β2*βi=1, that is to say as a pure ‘copy system’.
As a departure from the ideal mirror symmetry shown in FIG. 1, it is also possible in accordance with the invention for the product of the object plane-side imaging scale and the image plane-side imaging scale βo*βi to deviate from the exact value 1 and in particular to lie numerically within the limits 0.75≦βo*βi≦1.25, in particular the limits 0.85≦βo*βi≦1.15 and further in particular the limits 0.95≦βo*βi≦1.05. Those ranges, in accordance with the invention, define an almost symmetrical or ‘quasi-symmetrical’ structure.
It will be appreciated moreover that the present invention also embraces any splitting of optical elements into a plurality of optical elements, for example, but without limitation, in the form of mutually joined or wrung lens components insofar as the above-indicated relationships are fulfilled for the imaging scales βo, βi in question.
Furthermore in accordance with the invention any modification of the structure in principle shown in FIG. 1 is embraced, in which possibly further optical subsystems are arranged between the object plane-side subsystem 110 and the image plane-side subsystem 130, which respectively produce further intermediate images IMI3, IMI4, . . . .
The invention is also not restricted to the symmetrical position of the intermediate images IMI1 and IMI2, which is shown in FIG. 1. Rather the invention also embraces in particular any modification of the structure in principle shown in FIG. 1, in which the intermediate images IMI1 and IMI2 are not symmetrical with respect to the double folding mirror 121. Such alternative configurations are shown in FIGS. 2a)-2i) by way of example but without limitation.
In this respect FIG. 2a corresponds to the structure already shown in FIG. 1. It is to be noted that for example upon the production of the first intermediate image IMI1 in the light path only after reflection at the first mirror surface 122 (as can be seen from FIGS. 2b, 2c, 2e, 2f, 2h and 2i), the first mirror surface 122 by definition (see the foregoing definition) is still to be associated with the first optical subsystem 110 so that in this case the first optical subsystem 110 is catadioptric (and not purely refractive as shown in FIG. 1). In addition (as can be seen from FIGS. 2c, 2f and 2i), upon the production of the first intermediate image IMI1 in the light path only after passing through the positive lens group 124a, by way of example the positive lens group 124a can also still be associated with the first optical subsystem 100.
It is apparent to the man skilled in the art that a variation in the catadioptric structure shown in FIG. 1, in the context of the present invention, is possible in the above-indicated manners and many other ways.
A further possible structure as a matter of principle of an imaging system according to the present invention is shown in FIG. 3. The imaging system 300 has a first optical subsystem 310, a second optical subsystem 320, a third optical subsystem 330 and a fourth optical subsystem 340, wherein a total of three intermediate images IMI1-IMI3 are produced between the subsystems 310-340.
More precisely the first optical subsystem 310, along the optical axis, includes a first positive lens group 311, a second positive lens group 312, a third negative lens group 313 and a fourth positive lens group 314, as well as a first reflecting surface 315 of a plane mirror 316 which is reflecting at both sides and behind which a first intermediate image IMI1 is produced. The first intermediate image IMI1 is imaged on to a second intermediate image IMI2 by the second optical subsystem 320 which includes a first positive lens group 321, a second negative lens group 322 and a concave mirror 323. The second intermediate image IMI2 is imaged on to a third intermediate image IMI3 by the third optical subsystem 330 which includes a first positive lens group 331, a second negative lens group 332, a concave mirror 333 and a second reflecting surface 334 of the plane mirror 316 which is reflecting at both sides. The third intermediate image IMI3 is imaged on to the image plane ‘IP’ by the fourth optical subsystem 340 which comprises a first positive lens group 341, a second negative lens group 342, a third positive lens group 343 and a fourth positive lens group 344.
Similarly to the embodiment shown in FIG. 1, as can be seen from the diagrammatic sectional views in FIGS. 3b and 3c, it is possible to provide in adjoining relationship with the object plane OP and/or the image plane IP an immersion medium 350 or 360 respectively with a refractive index n of greater than one (for example deionised water), which is then between the object plane and the image plane respectively and an object plane-side and an image plane-side last optical element 351 and 361 respectively.
It will be appreciated that, similarly to FIG. 2, the invention also embraces modifications in which the respective intermediate images are at alternative positions so that depending on the respective relative position in relation to the intermediate image, by definition, individual optical components or groups can also be associated with another optical subsystem, wherein in turn the categorisation of the respective subsystem as catadioptric, catoptric or dioptric (that is to say purely refractive) can be modified.
In the imaging system 300 the imaging scale βo of the first, object plane-side subsystem 310 (which produces the image of the object field in the first intermediate image IMI1) precisely corresponds to the inverse of the imaging scale βi of the fourth, image plane-side subsystem 340 which produces the image field from the third intermediate image IMI3. Therefore once again the relationship βo*βi=1 applies. The imaging system 300 is also in particular doubled telecentric (that is to say at the object side and the image side).
Similarly to FIG. 1, in respect of the principle shown in FIG. 3 such ‘quasi-symmetrical’ modifications are also to be deemed to be embraced by the present invention, in which the product βo*βi deviates from the exact value 1 and in particular occurs in numerical terms within the limits 0.75≦βo*βi≦1.25, in particular the limits 0.85≦βo*βi≦1.15 and further in particular the limits 0.95≦βo*βi≦1.05.
The concave mirror 323 of the second optical subsystem 320 and the concave mirror 333 of the third optical subsystem 330 in turn in per se known manner permit effective compensation for the image field curvature produced by the subsystems 310 and 340 (each substantially uncorrected in itself) so that the imaging system 300 produces an image field which in the ideal case is flat, while being of a relatively simple structure.
A further structure which is possible in principle of an imaging system according to the present invention is shown in FIG. 4. The imaging system 400 has a first optical subsystem 410, a second optical subsystem 420 and a third optical subsystem 430 so that two intermediate images IMI1 and IMI2 are produced between the subsystems 410-430.
More precisely the first optical subsystem 410, along the optical axis, comprises a first positive lens group 411, a second positive lens group 412, a third negative lens group 413 and a fourth positive lens group 414, behind which a first intermediate image IMI1 is produced. The first intermediate image IMI1 is imaged on to a second intermediate image IMI2 by the second optical subsystem 420 which comprises a first concave mirror 421 and a second concave mirror 422 (which in the region of the optical axis as shown in FIG. 4 are alternatively cut off or interrupted or apertured). The second intermediate image IMI2 is imaged on to the image plane ‘IP’ by the third optical subsystem 430 which comprises a first positive lens group 431, a second negative lens group 432, a third positive lens group 433 and a fourth positive lens group 434.
In the imaging system 400 the imaging scale βo of the first, object plane-side subsystem 410 (which produces the image of the object field in the first intermediate image IMI 1) corresponds precisely to the inverse of the imaging scale βi of the third, image plane-side subsystem 430 which produces the image field from the second intermediate image IMI2. Accordingly the relationship βo*βi=1 again applies. The imaging system 400 is also in particular doubled telecentric (that is to say at the object side and the image side).
Similarly to FIGS. 1 and 3, in respect of the principle shown in FIG. 4 such ‘quasi-symmetrical’ modifications are also to be deemed to be embraced by the present invention, in which the product βo*βi deviates from the exact value 1 and in particular occurs in numerical terms within the limits 0.75≦βo*βi≦1.25, in particular the limits 0.85≦βo*βi≦1.15 and further in particular the limits 0.95≦βo*βi≦1.05.
Furthermore the concave mirrors 421 and 422 of the second optical subsystem 420 once again (in per se known manner) permit effective compensation of the image field curvature so that the imaging system 400 produces an image field which is flat in the ideal case, while being of a relatively simple structure.
Similarly to the embodiments shown in FIG. 1 and FIG. 3, as can be seen from the diagrammatic sectional views in FIGS. 4b and 4c it is possible to provide in adjoining relationship with the object plane OP and/or the image plane IP an immersion medium 450 and 460 respectively with a refractive index n of greater than 1 (for example deionised water), which is then between the object plane and the image plane respectively and an object plane-side and image plane-side last optical element 451 and 461 respectively.
FIG. 5 shows a meridional overall section through a complete catadioptric projection objective 500 in accordance with a further embodiment of the invention.
The design data of the projection objective 500 are set out in Table 1: radii and thicknesses are specified in millimeters. The figures above the projection objective 500 refer to selected surfaces of optical elements. The surfaces which are identified by dots and which are specified in Table 2a are aspherically curved, the curvature of those surfaces being given by the following aspheric formula:




  
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In that formula P denotes the camber height of the surface in question in parallel relationship with the optical axis, h denotes the radial spacing from the optical axis, r denotes the radius of curvature of the surface in question, K denotes the conical constant and C1, C2, . . . denote the aspheric constants set out in Table 2a.
The projection objective 500 is designed for a wavelength of about 193 nm and deionised water as the immersion liquid. The imaging scale of the projection objective 500 is β=1.00 and the numerical aperture NA=1.1, with an outside field diameter of 33 mm and an inside field diameter of 9.32 mm, which allows a rectangular field of 26*5.5 mm2. The wave front error is approximately 0.009*λ, with respect to the wave front RMS value averaged over the image field.
Table 2b sets out in relation to each surface the values sin(σo), σmax, sin(σmax) and sin(σmax)/sin(σo), wherein σmax gives the maximum angle of inclination of the rays which issue from the lens surface in question to the next lens surface, and wherein σo gives the angle of inclination of that edge ray which issues from the object point on the optical axis, relative to the optical axis. FIG. 10 shows a diagram in which, for each surface number (plotted on the horizontal axis), the associated value for sin(σmax)/sin(σo) is represented by the bar height. Accordingly the condition |sin σ/sin σo|>0.4 is satisfied for the aspheric surfaces ‘7’, ‘8’, ‘19’, ‘25’, ‘26’, ‘32’, ‘43’ and ‘44’.
A further structure which is possible in principle of an imaging system in accordance with the present invention is shown in FIG. 6. The imaging system 600 has a first dioptric group of overall positive refractive power 610 (hereinafter referred to as the positive lens group 610) and a second dioptric group of overall positive refractive power 620 (hereinafter referred to as the positive lens group 620). The first positive lens group 610 in turn comprises in succession a negative lens group 611, a positive lens group 612 and a negative lens group 613. The second positive lens group 620 in turn comprises in succession a negative lens group 621, a positive lens group 622 and a negative lens group 623.
Specific designs are now set out hereinafter, which are each constructed in accordance with the general design principle of FIG. 6, wherein the design is so selected in each case as to implement a structure which is at least substantially mirror image-symmetrical in relation to the pupil plane, with an imaging scale β, for which the condition 0.50≦β≦1.50 is fulfilled, which at the same time is doubled telecentric (that is to say telecentric at the object plane side and the image plane side) and in which image-side numerical apertures of at least NA=0.3 are embodied. In these embodiments ‘copy systems’ are respectively implemented with an imaging scale β close to 1, which are accordingly distinguished in that, with a symmetrical or at least quasi-symmetrical structure (and the advantages resulting therefrom, in particular in terms of production and internal error correction), they have a comparatively high resolution capability.
FIG. 7 shows a meridional overall section through a complete purely refractive (dioptric) projection projective 700 which is constructed in accordance with the design principle of FIG. 6. The design data of the projection objective 700 are set out in Table 3, while the surfaces specified in Table 4a are aspherically curved. The imaging scale of the projection objective 700 is β=1.00, the numerical aperture NA=0.3 and the field diameter is 100 mm. The wave front error is about 0.003*λ (with respect to the wave front RMS value averaged over the image field).
As can be seen from FIG. 7 and Table 4a the surfaces 2, 19, 30 and 47 are aspherically curved. Table 4b again specifies the values sin(σo), σmax, sin(σmax) and sin(σmax)/sin(σo) for each surface. FIG. 11 shows a diagram in which, for each surface number (plotted on the horizontal axis) the associated value for sin(σmax)/sin σo) is represented by the bar height.
The aspherically curved surfaces in each case involve lens surfaces in zones with divergent beams (surfaces 2, 30) or convergent beams (surfaces 19, 47) which in the imaging system are arranged at positions of relatively small optically free diameter (that is to say before or after positions with a maximum optically free diameter), and in respect of which, as shown in Table 4b and FIG. 11, the condition |sin σ/sin σo|>0.4 is fulfilled, thereby achieving correction of aberrations which is matched targetedly to the factors in the symmetrical system and thus particularly effective.
FIG. 8 shows a meridional overall section through a further complete, purely refractive projection objective 800 which is constructed in accordance with the design principle of FIG. 6. The design data of the projection objective 800 are set out in Table 5, wherein the surfaces identified by dots and specified in Table 6a are aspherically curved.
The imaging scale of the projection objection 800 is β=1.00, the numerical aperture NA=0.6 and the field diameter is 30 mm. The wave front error is about 0.015*λ (with respect to the wave front RMS value averaged over the image field).
As can be seen from FIG. 8 and Table 6a the surfaces 2, 13, 32 and 43 are aspherically curved. Table 6b gives the values sin(σo), σmax, sin(σmax) and sin(σmax)/sin(σo) for each surface. FIG. 12 again shows a diagram in which, for each surface number (plotted on the horizontal axis), the associated value for sin(σmax)/sin(σo) is represented by the bar height. Accordingly the condition |sin σ/sin σo|>0.4 is fulfilled for the surfaces ‘2’, ‘13’ and ‘43’.
FIG. 9 shows a meridional overall section through a further complete, purely refractive projection objective which is constructed in accordance with the design principle of FIG. 6 and which is of a not completely symmetrical structure. The design data of the projection objection 800 are set out in Table 7, wherein the surfaces characterised by dots and specified in Table 8a are aspherically curved. The imaging scale of the projection objective 800 is β=0.50, the numerical aperture NA=0.6 and the field diameter is 50 mm. The wave front error is about 0.004*λ (with respect to the wave front RMS value averaged over the image field).
As can be seen from FIG. 9 and Table 8a, the surfaces 2, 19, 24 and 41 are aspherically curved. Table 8b specifies for each surface the values sin(σo), σmax, sin(σmax) and sin(σmax)/sin(σo). FIG. 13 again shows a diagram in which, for each surface number (plotted on the horizontal axis), the associated value for sin(σmax)/sin(σo) is represented by the bar height. Accordingly the condition |sin σ/sin σo|>0.4 is fulfilled for all aspherical surfaces. In this case also a particularly effective correction of aberrations is achieved.
FIG. 14 shows the structure in principle of a projection exposure apparatus. As shown in FIG. 14 a projection exposure apparatus 10 has an illumination device 11 and a projection objective 12. The projection objective 12 comprises a lens arrangement 13 with an aperture plate AP, wherein an optical axis OA is defined by the lens arrangement 13 which is only diagrammatically indicated. Arranged between the illumination device 11 and the projection objective 12 is a mask 14 which has a structure in the micrometer to nanometer range and which is held in the beam path by means of a mask holder. The image of the structure is produced by means of the projection objective 12 on the image plane IP in which a photosensitive substrate 16 positioned by a substrate holder 17, or a wafer, is held.
An imaging system according to the invention, for example in accordance with one of the above-described embodiments, is used as the projection objective 12. The apparatus can also advantageously be used for wafer level packaging, in which comparatively large areas (for example between two and four chips of a size 26 mm*33 mm) are exposed in a step (‘step-and-repeat’ mode) in order in particular to produce a plurality of semiconductor chips produced on a wafer with electrical contacts in a lithography process.
To sum up the present application presents imaging systems having an imaging scale of close to 1 (‘copy systems’), in particular for microlithography, which on the one hand are of a comparatively simple structure which is advantageous from the point of view of production engineering and which on the other hand make it possible to achieve relatively high levels of resolution.
If the invention has also been described by reference to specific embodiments, numerous variations and alternative embodiments will present themselves to the man skilled in the art. Accordingly it will be appreciated by the man skilled in the art that such variations and alternative embodiments are also embraced by the present invention and the scope of the invention is limited only in the sense of the accompanying claims and equivalents thereof.







TABLE 1







(DESIGN DATA for FIG. 5)











SUR-






FACE
RADII
THICKNESSES
GLASSES
DIAMETER














1
0.000000
0.000000
H2OV
18.832


2
0.000000
31.351111
SIO2V
18.832


3
−76.827122
5.490428
AIR
39.038


4
−220.265044
41.109617
SIO2V
51.925


5
−109.799301
0.991614
AIR
69.228


6
−621.687484
22.403985
SIO2V
83.807


7
−160.262417
0.981642
AIR
89.064


8
861.455748
60.227866
SIO2V
103.424


9
−148.068950
10.117252
AIR
109.392


10
0.000000
0.000000
AIR
127.886


11
0.000000
5.805341
AIR
127.886


12
1467.209534
62.725007
SIO2V
129.476


13
−222.943738
13.160623
AIR
133.829


14
672.972896
56.541030
SIO2V
130.895


15
−294.887142
1.000740
AIR
129.559


16
191.084097
65.379964
SIO2V
97.669


17
375.563222
26.988297
AIR
72.978


18
−169.889516
9.494007
SIO2V
69.431


19
330.690785
36.198473
AIR
64.258


20
−95.586010
9.495976
SIO2V
63.619


21
−2451.271499
1.013402
AIR
71.048


22
186.204930
24.070106
SIO2V
77.673


23
781.623758
32.415180
AIR
77.999


24
0.000000
262.078507
AIR
80.953


25
−199.787792
−262.078507
REFL
144.265


26
199.787792
262.078507
REFL
144.261


27
0.000000
32.415180
AIR
80.970


28
−781.623758
24.070106
SIO2V
78.021


29
−186.204930
1.013402
AIR
77.696


30
2451.271499
9.495976
SIO2V
71.070


31
95.586010
36.198473
AIR
63.639


32
−330.690785
9.494007
SIO2V
64.277


33
169.889516
26.988297
AIR
69.463


34
−375.563222
65.379964
SIO2V
73.005


35
−191.084097
1.000740
AIR
96.183


36
294.887142
56.541030
SIO2V
119.915


37
−672.972896
13.160623
AIR
121.525


38
222.943738
62.725007
SIO2V
122.942


39
−1467.209534
5.805341
AIR
117.459


40
0.000000
0.000000
AIR
115.680


41
0.000000
10.117252
AIR
115.680


42
148.068950
60.227866
SIO2V
107.756


43
−861.455748
0.981642
AIR
102.343


44
160.262417
22.403985
SIO2V
88.976


45
621.687484
0.991614
AIR
83.723


46
109.799301
41.109617
SIO2V
69.182


47
220.265044
5.490428
AIR
51.880


48
76.827122
31.351111
SIO2V
39.018


49
0.000000
2.000000
H2OV
18.828


50
0.000000
0.000000
AIR
16.500
















TABLE 2a





(ASPHERIC CONSTANTS for FIG. 5)




















Sur
7
8
12
19
25





K
0
0
0
0
−0.474354


C1
1.016586e−07
−5.783301e−08
−3.233669e−08
4.982706e−08
−3.050790e−09


C2
6.908432e−12
1.173196e−12
5.015975e−13
−2.918139e−12
−4.716896e−14


C3
2.545336e−16
−3.123441e−18
1.496010e−17
1.879762e−16
−6.952851e−19


C4
−1.097430e−20
−3.354956e−22
−1.011225e−21
−1.075777e−19
−1.865614e−23


C5
−3.517586e−24
8.966032e−27
1.595586e−26
3.174059e−23
2.297720e−29


C6
1.602876e−28
−2.609994e−30
−3.904964e−32
−3.392173e−27
−4.041193e−33





SRF
26
32
39
43
44





K
−0.474354
0
0
0
0


C1
3.050790e−09
−4.982706e−08
3.233669e−08
5.783301e−08
−1.016586e−07


C2
4.716896e−14
2.918139e−12
−5.015975e−13
−1.173196e−12
−6.908432e−12


C3
6.952851e−19
−1.879762e−16
−1.496010e−17
3.123441e−18
−2.545336e−16


C4
1.865614e−23
1.075777e−19
1.011225e−21
3.354956e−22
1.097430e−20


C5
−2.297720e−29
−3.174059e−23
−1.595586e−26
−8.966032e−27
3.517586e−24


C6
4.041193e−33
3.392173e−27
3.904964e−32
2.609994e−30
−1.602876e−28
















TABLE 2b







(Values sin(σ0), σmax, sin(σmax) and


sin(σmax)/sin(σ0) for FIG. 5)


sin(σ0) = 0.76












SURFACE
σmax
Sin(σmax)
sin(σmax)/sin(σ0)
















1
53.019027
0.798819
1.043089



2
47.320398
0.735139
0.959937



3
70.368891
0.941863
1.229874



4
43.358362
0.686543
0.89648



5
49.304534
0.758169
0.990009



6
32.464766
0.536767
0.700904



7
45.552832
0.71388
0.932176



8
28.953332
0.484084
0.632111



9
17.679933
0.303691
0.396556



10
17.679933
0.303691
0.396556



11
17.679933
0.303691
0.396556



12
12.965369
0.224356
0.292961



13
11.112407
0.192729
0.251663



14
10.437841
0.181163
0.236561



15
32.848716
0.542408
0.708271



16
29.854681
0.497789
0.650007



17
43.81267
0.692286
0.90398



18
21.108003
0.360117
0.470237



19
31.040202
0.515626
0.673298



20
18.419158
0.315957
0.412573



21
29.552453
0.493207
0.644024



22
18.381517
0.315334
0.411759



23
29.916025
0.498717
0.651219



24
29.916025
0.498717
0.651219



25
35.01861
0.573828
0.749298



26
29.910029
0.498626
0.6511



27
29.910029
0.498626
0.6511



28
18.37719
0.315262
0.411666



29
29.551369
0.49319
0.644002



30
18.418801
0.315951
0.412566



31
31.026412
0.515419
0.673029



32
21.096771
0.359934
0.469998



33
43.76743
0.691717
0.903235



34
29.825194
0.497342
0.649424



35
32.817596
0.541952
0.707675



36
10.444065
0.18127
0.236701



37
11.101869
0.192548
0.251427



38
12.021847
0.208279
0.271968



39
17.001443
0.292387
0.381796



40
17.001443
0.292387
0.381796



41
17.001443
0.292387
0.381796



42
26.597123
0.447702
0.584604



43
42.901226
0.68072
0.888877



44
32.087267
0.531196
0.69363



45
49.092717
0.755754
0.986854



46
41.981503
0.668875
0.873409



47
69.609962
0.93733
1.223955



48
44.892489
0.705762
0.921576



49
50.077517
0.766897
1.001405



50
50.077517
0.766897
1.001405

















TABLE 3







(DESIGN DATA for FIG. 7)











SUR-






FACE
RADII
THICKNESSES
GLASSES
DIAMETER














1
0.000000
0.000000
AIR
64.385


2
345.073757
9.998854
SIO2V
68.260


3
157.409322
49.701121
AIR
69.507


4
−122.244531
52.029367
SIO2V
73.843


5
−199.261606
7.652028
AIR
102.294


6
−568.903701
44.561989
SIO2V
116.138


7
−232.283434
1.408075
AIR
124.840


8
−2953.846302
38.798867
SIO2V
136.203


9
−315.908103
2.491849
AIR
138.421


10
861.472293
39.737967
SIO2V
142.180


11
−572.292490
1.000146
AIR
142.095


12
365.071260
37.306671
SIO2V
134.826


13
−5863.202081
12.821175
AIR
132.380


14
224.229259
11.028244
SIO2V
113.576


15
175.995309
16.598766
AIR
106.108


16
250.203130
39.358554
SIO2V
104.755


17
−802.840033
26.807982
AIR
100.942


18
−366.621868
10.027110
SIO2V
80.564


19
−361.186777
5.350603
AIR
76.667


20
1057.722394
18.501287
SIO2V
66.182


21
164.683932
18.680931
AIR
54.842


22
−460.473682
10.867772
SIO2V
51.724


23
748.912892
7.757540
AIR
47.985


24
0.000000
0.000000
AIR
45.788


25
0.000000
7.757540
AIR
45.788


26
−748.912892
10.867772
SIO2V
47.985


27
460.473682
18.680931
AIR
51.724


28
−164.683932
18.501287
SIO2V
54.842


29
−1057.722394
5.350603
AIR
66.183


30
361.186777
10.027110
SIO2V
76.667


31
366.621868
26.807982
AIR
80.565


32
802.840033
39.358554
SIO2V
100.942


33
−250.203130
16.598766
AIR
104.755


34
−175.995309
11.028244
SIO2V
106.108


35
−224.229259
12.821175
AIR
113.577


36
5863.202081
37.306671
SIO2V
132.381


37
−365.071260
1.000146
AIR
134.826


38
572.292490
39.737967
SIO2V
142.095


39
−861.472293
2.491849
AIR
142.181


40
315.908103
38.798867
SIO2V
138.421


41
2953.846302
1.408075
AIR
136.203


42
232.283434
44.561989
SIO2V
124.841


43
568.903701
7.652028
AIR
116.139


44
199.261606
52.029367
SIO2V
102.295


45
122.244531
49.701121
AIR
73.844


46
−157.409322
9.998854
SIO2V
69.507


47
−345.073757
37.512977
AIR
68.260


48
0.000000
0.000000
AIR
50.000
















TABLE 4a







(ASPHERIC CONSTANTS for FIG. 7)









SURFACE












2
19
30
47















K
0
0
0
0


C1
1.635346e−07
4.393822e−08
−4.393822e−08
−1.635346e−07


C2
2.980756e−13
−1.559047e−12
1.559047e−12
−2.980756e−13


C3
−8.385352e−16
5.155370e−17
−5.155370e−17
8.385352e−16


C4
3.330405e−20
−1.604317e−21
1.604317e−21
−3.330405e−20


C5
4.154983e−24
−6.843003e−26
6.843003e−26
−4.154983e−24


C6
−3.137835e−28
8.771933e−30
−8.771933e−30
3.137835e−28
















TABLE 4b







(Values sin(σ0), σmax, sin(σmax) and


sin(σmax)/sin(σ0) for FIG. 7)


sin(σ0) = 0.3















sin(σmax)/



SURFACE
σmax
Sin(σmax)
sin(σ0)
















1
20.980777
0.358045
1.193482



2
16.032073
0.276167
0.920558



3
26.493082
0.446078
1.486925



4
30.349565
0.505261
1.684203



5
30.04742
0.500703
1.669011



6
23.365266
0.39658
1.321935



7
18.147543
0.311456
1.038187



8
12.50458
0.216511
0.721705



9
13.770404
0.238025
0.793416



10
8.560585
0.148851
0.496169



11
12.586824
0.217912
0.726375



12
13.738015
0.237476
0.791586



13
22.584641
0.384037
1.280124



14
25.413533
0.429137
1.430456



15
18.683471
0.320331
1.067769



16
20.867881
0.356204
1.187347



17
40.078208
0.643817
2.146056



18
17.979781
0.308673
1.028909



19
36.053092
0.58852
1.961732



20
23.703628
0.401995
1.339982



21
26.096703
0.439875
1.466251



22
13.713072
0.237053
0.790176



23
20.650346
0.352654
1.175514



24
20.650346
0.352654
1.175514



25
20.650346
0.352654
1.175514



26
13.713169
0.237055
0.790182



27
26.096876
0.439878
1.46626



28
23.703746
0.401996
1.339988



29
36.053292
0.588522
1.961742



30
17.979876
0.308674
1.028914



31
40.07847
0.64382
2.146068



32
20.867993
0.356206
1.187353



33
18.683592
0.320333
1.067775



34
25.413664
0.429139
1.430462



35
22.584776
0.384039
1.280131



36
13.738094
0.237477
0.791591



37
12.58674
0.217911
0.72637



38
8.560548
0.14885
0.496167



39
13.770363
0.238024
0.793414



40
12.504641
0.216512
0.721708



41
18.147631
0.311458
1.038192



42
23.365383
0.396582
1.321941



43
30.04757
0.500705
1.669018



44
30.349716
0.505263
1.68421



45
26.493216
0.44608
1.486932



46
16.032038
0.276167
0.920556



47
20.980777
0.358045
1.193482



48
20.980777
0.358045
1.193482

















TABLE 5







(DESIGN DATA for FIG. 8)











SUR-






FACE
RADII
THICKNESSES
GLASSES
DIAMETER














1
0.000000
0.000000
AIR
43.498


2
−110.206131
9.995109
SIO2V
38.299


3
602.886980
32.586560
AIR
49.428


4
−174.780467
25.227256
SIO2V
73.812


5
−128.362443
0.998338
AIR
84.320


6
−206.429154
41.325957
SIO2V
95.205


7
−126.363749
0.998305
AIR
104.003


8
−944.270193
39.835037
SIO2V
134.040


9
−263.024205
0.997852
AIR
138.462


10
−677.420151
52.366344
SIO2V
146.982


11
−221.621713
63.513254
AIR
150.022


12
256.322466
61.426348
SIO2V
150.005


13
5820.404257
0.995348
AIR
146.275


14
263.146947
12.710594
SIO2V
133.122


15
148.054990
37.362299
AIR
117.582


16
286.148841
43.991383
SIO2V
117.227


17
−765.188221
0.994643
AIR
115.104


18
703.421400
9.974056
SIO2V
106.996


19
170.593640
40.183067
AIR
96.312


20
−718.344540
26.720379
SIO2V
95.648


21
−10582.040304
4.587883
AIR
93.824


22
0.000000
0.000000
AIR
93.362


23
0.000000
4.587883
AIR
93.362


24
10582.040304
26.720379
SIO2V
93.824


25
718.344540
40.183067
AIR
95.647


26
−170.593640
9.974056
SIO2V
96.311


27
−703.421400
0.994643
AIR
106.994


28
765.188221
43.991383
SIO2V
115.102


29
−286.148841
37.362299
AIR
117.225


30
−148.054990
12.710594
SIO2V
117.580


31
−263.146947
0.995348
AIR
133.119


32
−5820.404257
61.426348
SIO2V
146.271


33
−256.322466
63.513254
AIR
150.002


34
221.621713
52.366344
SIO2V
150.017


35
677.420151
0.997852
AIR
146.976


36
263.024205
39.835037
SIO2V
138.456


37
944.270193
0.998305
AIR
134.033


38
126.363749
41.325957
SIO2V
104.000


39
206.429154
0.998338
AIR
95.201


40
128.362443
25.227256
SIO2V
84.318


41
174.780467
32.586560
AIR
73.809


42
−602.886980
9.995109
SIO2V
49.424


43
110.206131
37.151441
AIR
38.296


44
0.000000
0.000000
AIR
15.000
















TABLE 6a







(ASPHERIC CONSTANTS for FIG. 8)









Sur.












2
13
32
43















K
0
0
0
0


C1
−1.104035e−07
2.075608e−09
−2.075608e−09
1.104035e−07


C2
7.594942e−11
−8.718294e−14
8.718294e−14
−7.594942e−11


C3
1.267432e−14
8.999931e−19
−8.999931e−19
−1.267432e−14


C4
5.960824e−18
2.616878e−23
−2.616878e−23
−5.960824e−18


C5
−4.276279e−22
−4.473962e−29
4.473962e−29
4.276279e−22


C6
−4.805888e−25
0.000000e+00
0.000000e+00
4.805888e−25
















TABLE 6b







(Values sin(σ0), σmax, sin(σmax) and


sin(σmax)/sin(σ0) for FIG. 8)


sin(σ0) = 0.6















sin(σmax)/



SURFACE
σmax
Sin(σmax)
sin(σ0)
















1
37.496288
0.608695
1.014491



2
30.619845
0.509326
0.848877



3
59.774323
0.864034
1.440056



4
46.425105
0.724457
1.207429



5
49.449616
0.759818
1.266363



6
41.342567
0.660544
1.100906



7
33.127799
0.546494
0.910823



8
23.851118
0.40435
0.673917



9
19.356152
0.33143
0.552383



10
16.897909
0.290659
0.484432



11
5.363969
0.093479
0.155799



12
13.80038
0.238533
0.397555



13
20.643042
0.352535
0.587558



14
24.162933
0.409322
0.682203



15
5.265192
0.091763
0.152938



16
11.792697
0.204365
0.340609



17
24.385146
0.412857
0.688095



18
18.693109
0.32049
0.53415



19
9.423826
0.163731
0.272886



20
3.697937
0.064494
0.107491



21
5.778886
0.100687
0.167811



22
5.778886
0.100687
0.167811



23
5.778886
0.100687
0.167811



24
3.697933
0.064494
0.107491



25
9.422589
0.16371
0.27285



26
18.692274
0.320476
0.534127



27
24.383867
0.412837
0.688061



28
11.792024
0.204354
0.34059



29
5.265224
0.091764
0.152939



30
24.161967
0.409306
0.682177



31
20.641908
0.352516
0.587527



32
13.799637
0.23852
0.397534



33
5.364627
0.093491
0.155818



34
16.897321
0.290649
0.484415



35
19.355533
0.33142
0.552366



36
23.850235
0.404336
0.673894



37
33.12658
0.546476
0.910794



38
41.340985
0.660523
1.100872



39
49.447799
0.759797
1.266329



40
46.423359
0.724436
1.207394



41
59.772094
0.864014
1.440024



42
30.61934
0.509318
0.848864



43
37.496524
0.608698
1.014497



44
37.496524
0.608698
1.014497

















TABLE 7







(DESIGN DATA for FIG. 9)











SUR-






FACE
RADII
THICKNESSES
GLASSES
DIAMETER














1
0.000000
−5.341329
AIR
59.950


2
299.070524
9.999009
SIO2V
61.031


3
128.974788
32.289908
AIR
62.135


4
−173.544932
46.025186
SIO2V
64.265


5
12309.595011
14.046499
AIR
92.614


6
−483.608290
36.247841
SIO2V
96.362


7
−318.245849
0.999703
AIR
111.852


8
−659.889358
32.441029
SIO2V
119.710


9
−250.111461
1.018201
AIR
124.851


10
−1047.358535
47.729697
SIO2V
137.060


11
−234.579432
3.213912
AIR
140.510


12
911.507519
58.745717
SIO2V
149.668


13
−327.437653
2.073132
AIR
149.991


14
304.595360
22.725962
SIO2V
131.912


15
485.421675
1.040651
AIR
128.522


16
197.221426
29.318841
SIO2V
119.484


17
270.755969
41.544772
AIR
112.667


18
−588.786019
24.261200
SIO2V
109.070


19
−196.170023
0.999085
AIR
106.788


20
−657.069925
19.102272
SIO2V
90.642


21
182.514870
37.989240
AIR
75.090


22
−161.495001
9.999701
SIO2V
73.759


23
180.130604
11.232180
AIR
73.717


24
293.361910
10.000018
SIO2V
74.928


25
224.403691
42.529296
AIR
76.180


26
0.000000
29.092329
SIO2V
87.435


27
−258.425147
13.722921
AIR
90.453


28
−553.437071
10.055318
SIO2V
94.043


29
1718.800624
42.001421
AIR
97.517


30
0.000000
2.659300
AIR
109.374


31
0.000000
17.554099
AIR
110.899


32
−577.752494
26.202031
SIO2V
114.405


33
−268.536580
37.243141
AIR
118.669


34
−373.594070
43.678689
SIO2V
134.266


35
−192.061692
0.998733
AIR
138.153


36
286.654647
44.175924
SIO2V
147.250


37
1627.982099
0.999097
AIR
145.713


38
199.943323
48.106011
SIO2V
136.527


39
562.883307
2.334523
AIR
132.273


40
198.974190
57.415101
SIO2V
118.393


41
356.393341
17.889262
AIR
98.745


42
0.000000
111.686939
SIO2V
95.296


43
109.843628
7.354831
AIR
40.312


44
128.058533
16.006724
SIO2V
37.641


45
0.000000
10.594719
AIR
33.221


46
0.000000
0.000000
AIR
25.000
















TABLE 8a







(ASPHERIC CONSTANTS for FIG. 9)









Sur












2
19
24
41















K
0
0
0
0


C1
1.827036e−07
6.415216e−08
−2.800645e−08
3.478343e−09


C2
−5.671165e−12
−1.281881e−12
6.849816e−13
−3.566014e−13


C3
2.603509e−16
5.622084e−17
−2.872650e−17
−4.680126e−18


C4
2.803459e−20
−1.605043e−21
−4.172581e−22
−2.291221e−22


C5
−1.250454e−24
4.028615e−26
−1.716142e−25
2.754912e−27


C6
−1.716678e−28
−3.801309e−31
−2.725229e−29
−2.307098e−31
















TABLE 8b







(Values sin(σ0), σmax, sin(σmax) and


sin(σmax)/sin(σ0) zu FIG. 9)


sin(σ0) = 0.3












SURFACE
σmax
Sin(σmax)
sin(σmax)/sin(σ0)
















1
18.751111
0.321449
1.071496



2
14.915199
0.257382
0.857939



3
28.046568
0.470176
1.567254



4
25.773856
0.434808
1.449361



5
43.137055
0.68373
2.279099



6
31.135019
0.517043
1.723476



7
37.194781
0.604511
2.015038



8
27.208575
0.457219
1.524062



9
25.671241
0.433195
1.443983



10
19.033118
0.326105
1.087018



11
11.299271
0.195928
0.653093



12
7.579809
0.131903
0.439677



13
14.786447
0.25521
0.850699



14
18.719067
0.320919
1.06973



15
20.611085
0.352013
1.173376



16
26.693437
0.449204
1.497348



17
27.874205
0.467519
1.558397



18
12.857795
0.222526
0.741752



19
40.108411
0.64422
2.1474



20
20.522439
0.350564
1.168548



21
18.40135
0.315662
1.052208



22
14.104693
0.243687
0.812291



23
29.823058
0.49731
1.657699



24
15.510414
0.267406
0.891353



25
32.825405
0.542067
1.806889



26
20.323042
0.347303
1.157677



27
22.493914
0.382575
1.275249



28
17.376007
0.298633
0.995442



29
29.833082
0.497462
1.658205



30
29.833082
0.497462
1.658205



31
29.833082
0.497462
1.658205



32
23.096337
0.392267
1.307558



33
21.337845
0.363856
1.212854



34
21.239002
0.362249
1.207496



35
7.075173
0.123168
0.41056



36
13.244947
0.229108
0.763693



37
18.573975
0.31852
1.061732



38
23.042112
0.391397
1.304656



39
31.023964
0.515383
1.717943



40
31.351589
0.520274
1.734248



41
40.773739
0.653058
2.176859



42
24.735264
0.418415
1.394715



43
41.893946
0.667738
2.225793



44
23.127512
0.392768
1.309226



45
37.809891
0.613028
2.043427



46
37.809891
0.613028
2.043427

## Claims

1. An imaging system for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system, the imaging system comprising:
an object plane-side subsystem which produces a first intermediate image with an object plane-side imaging scale βo;
at least one further subsystem which produces a further intermediate image between the first intermediate image and the image plane; and
an image plane-side subsystem which images the further intermediate image into the image plane with an image plane-side imaging scale βi;
wherein the condition 0.75≦βo*βi≦1.25 is satisfied, and all subsystems are arranged on a common, non-folded optical axis.

2. An imaging system as set forth in claim 1 wherein the condition 0.85≦βo*βi≦1.15 is fulfilled.

3. An imaging system as set forth in claim 1 wherein for a total imaging scale β the condition 0.75≦β≦1.25 is fulfilled.

4. An imaging system as set forth in claim 1 wherein the further subsystem has at least one concave mirror.

5. An imaging system as set forth in claim 1 wherein the imaging system is substantially telecentric at the image plane side.

6. An imaging system as set forth in claim 1 wherein the imaging system is substantially telecentric at the object plane side.

7. An imaging system as set forth in claim 1 wherein the object plane and the image plane are arranged in mutually parallel relationship.

8. An imaging system as set forth in claim 1 wherein the further subsystem images the first intermediate image into the second intermediate image.

9. An imaging system as set forth in claim 1 wherein the image-side numerical aperture (NA) is greater than 0.6.

10. A microlithographic projection exposure apparatus for the production of microstructured components comprising an imaging system as set forth in claim 1.

11. A process for the microlithographic production of microstructured components comprising the following steps:
providing a substrate to which a layer of a photosensitive material is at least region-wise applied;
providing a mask which has structures to be imaged;
providing a projection exposure apparatus having an imaging system as set forth in claim 1; and
projecting at least a part of the mask on to a region of the layer by means of the projection exposure apparatus.

12. A process for wafer level packaging in which a plurality of semiconductor chips produced on a wafer are provided with electrical contacts in a lithography process, wherein an imaging system as set forth in claim 1 is used in the lithography process.

13. An imaging system for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system, the imaging system comprising:
a first dioptric group in front of a pupil plane of overall positive refractive power;
at least one second dioptric group after a pupil plane of overall positive refractive power; and
an imaging scale β′, for which the condition 0.50≦β′≦1.50 is fulfilled;
wherein the imaging system is of a telecentric configuration at the object plane side and the image plane side; and
wherein there is provided at least one aspheric lens surface, the imaging system has a numerical aperture having a value larger than 0.15, and an operating wavelength of the imaging system is less than 300 nm.

14. An imaging system as set forth in claim 13 wherein the condition 0.80≦β′≦1.20 is fulfilled for the imaging scale β′.

15. An imaging system as set forth in claim 13 wherein the image-side numerical aperture (NA) is greater than 0.30.

16. An imaging system as set forth in claim 13 wherein the imaging system is of a substantially mirror image-symmetrical configuration in relation to a pupil plane of the imaging system.

17. An imaging system as set forth in claim 13 wherein in the image plane the imaging system produces an image field of a diameter of at least 30 mm.

18. An imaging system as set forth in claim 13 wherein an intermediate space between the image plane-side last optical element and the image plane and/or an intermediate space between the object plane-side last optical element and the object plane is filled with an immersion medium which is of a refractive index of greater than one.

19. An imaging system as set forth in claim 13 wherein the imaging system is designed for a wavelength of 248 nm.

20. An imaging system according to claim 13, wherein there is provided at least on aspheric lens surface for which the condition |sinσmax/sinσo|>0.4 is fulfilled, wherein σmax gives the maximum angle of inclination of the rays which emanate from the lens surface to the next lens surface and wherein σo gives the angle of inclination of that edge ray which emanates from the object point on the optical axis to the optical axis.

21. An imaging system for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system, the imaging system comprising:
an object plane-side subsystem which produces a first intermediate image with an object plane-side imaging scale βo;
at least one further subsystem which produces a further intermediate image between the first intermediate image and the image plane; and
an image plane-side subsystem which images the further intermediate image into the image plane with an image plane-side imaging scale βi;
wherein the condition 0.75≦βo*βi≦1.25 is satisfied, and the further subsystem comprises two concave mirrors.

22. An imaging system for imaging a mask which can be positioned in an object plane of the imaging system on to a photosensitive layer which can be positioned in an image plane of the imaging system, the imaging system comprising:
an object plane-side subsystem which produces a first intermediate image with an object plane-side imaging scale βo;
at least one further subsystem which produces a further intermediate image between the first intermediate image and the image plane; and
an image plane-side subsystem which images the further intermediate image into the image plane with an image plane-side imaging scale βi;
wherein the condition 0.75≦βo*βi 1.25 is satisfied, and the object plane-side subsystem and the image plane-side subsystem are purely refractive.