The invention relates to an optical system for EUV projection micro- lithography and a projection lighting system with such an optical system. The invention also relates to a method for adjusting a lighting setting, a method of producing a micro- or nanostructured component and a component produced by means of the method.

Obscurations in an objective can lead to an undesirable worsening of the image quality.

Obscuration stops are known from WO 2006/069725 Al and US

2006/0109436 Al . The problem addressed by the present invention is to develop an optical system with an obscuration stop such that an improved image quality of the projection optical system is made possible.

This problem is solved according to the invention by the features of claim 1.

The core of the invention consists, in an optical system with projection optics obscured by a first obscuration and a lighting setting produced by lighting optics, of adjusting the said obscuration of the projection optics and lighting setting to one another in a suitable manner. In particular, the obscuration and the lighting setting are adjusted to one another such that the image at least of a predetermined order of diffraction of at least one light channel, in particular all light channels, of the lighting setting in the region of the position of the obscuration in the beam path of the projection optics and the obscuration are non-overlapping at least by a predetermined amount.

The image of a predetermined order of diffraction is defined to be non- overlapping relative to the obscuration, if at most a predetermined maximum amount, in particular at most 50 %, in particular at most 30 %, in particular at most 10%, of the intensity of said order of diffraction falls on the area taken up by the obscuration and is thus obscured. The image of the lighting setting, in particular one or more predetermined orders of diffraction of the image of the lighting setting has in particular a maximum intensity I _max , and the area in which the intensity of the lighting setting is greater than a limit intensity In _m < 0.5 I _max , in particular Ii _im < 0.3 Imax, in particular I _Hm < 0.1 I _max , in particular I _Hm < 0.05 I _max , in particular < 0.01 I _max and the area of the obscuration are non-overlapping. In this way in particular the total intensity of the image of the lighting setting can be taken into consideration. It is also possible to take into consideration only the 0 order of diffraction and/or the 1st and/or -1st order of diffraction and/or higher orders of diffraction.

The lighting setting can be considered as a whole here. According to one advantageous embodiment it is also possible to consider the light channels of the lighting setting in isolation, i.e. adjust the light channels and the obscuration to one another individually.

By means of the adjustment according to the invention of the obscuration and the lighting setting to one another the optical properties of the optical system, in particular the image-side contrast, can be improved significantly. This is achieved in particular in that the illuminating light is avoi- ded, which falls in the case of a reticle with predetermined structures and a given obscuration at least in a specific amount on the obscuration and thus does not contribute to the display of the structures of the reticle in the image field, and/or leads to a worsening of this image, in particular a loss of contrast.

In the exemplary embodiment according to claim 2 the obscuration is formed by a holding device for the arrangement of an obscuration stop in the projection optics.

The holding device and the lighting setting are adjusted to one another in particular such that the intensity of the lighting setting at the holding position of the holding device has a maximum intensity I _max and a limit intensity Iiim < 0.1 I _max , and the area in which the intensity of the lighting setting is greater than the limit intensity Ii _im and the holding device are non- overlapping. The limit intensity Ii _im can be determined as required. In particular, I _lim < 0.5 I _max , in particular I _Hm < 0.3 I _max , in particular I _Hm < 0.1 I _max , in particular I _]im < 0.05 I _max , in particular I]j _m < 0.01 I _max . The holding device of the obscuration and the lighting setting are thus adjusted to one another such that the obscuration is arranged completely in areas in which the intensity of the lighting setting does not exceed a predetermined limit intensity l _Vim . In this case the limit intensity is less than 50 % of the maximum intensity I _max of the lighting setting in the position of ob- scuration, in particular is less than 30 % of the I _max , in particular less than 10 % of the I _max in particular less than 5 % of the I _max , in particular less than 1 % of the I _max . A pupil obscuration allows in certain design concepts - particularly in systems with a high numerical aperture - a significant reduction in the angle of incidence on certain optical elements of the system, as beam bundles, which in an unobscured case have to run past an optical element, in an ob- scured case can pass through an opening of the optical element. As this through opening of the optical element generally does not lie in a pupil plane of the optical system, it first of all generates a field-dependent shadowing of the outlet pupil; and thus leads to field-dependent image properties. To eliminate this field dependency, in a pupil plane of the system an obscuration stop can be inserted, which is dimensioned, so that the through opening of the optical element lies completely in the shadow of the obscuration stop. According to the invention it has been recognised that the mechanical elements, which are used for arranging the obscuration stop in the projection optics, can lead to an undesirable worsening of the image qual- ity . This applies in particular, if a central area of the pupil has to be shaded, so that a mechanical device has to hold the obscuration stop externally through the imaging light bundle. Furthermore, it has also been recognised that these kinds of interferences can be reduced or completely avoided by a suitable design of the holding device. This can be achieved in that the hold- ing device is designed to be adjusted to a predefined lighting setting, i.e. a predefined light distribution. A second order rotationally symmetrical device is particularly advantageous, as it is adjusted both to a lighting setting with a dipole structure and to one with a quadrupole structure. With such a second order rotationally symmetrical holding device the holding elements of the holding device, in particular holding struts, move into one another upon a rotation of the holding device by 180° around a predefined axis. Such a second order rotationally symmetrical holding device can also be designed to be a fourth order or multiple order rotationally symmetrical device. An nth order of rotational symmetry corresponds to the transition into one another of holding elements of the holding device upon a rotation about the predetermined axis by an angle of 360°/n. A holding device, which is designed to have a second order rotational symmetry, can be adjusted in particular by a simple rotation to the orientation of predetermined dipole or quadrupole structure.

As required, the holding device can be designed to have fourth order rotationally symmetry or not. A fourth order rotationally symmetrical design of the holding device is advantageous in particular for lighting settings with a quadrupole structure. It enables a particularly stable and reliable holding of the obscuration stop. A holding device with a second order and not a fourth order rotational symmetry can be advantageous in particular for lighting settings with a dipole structure. By means of the second order but not fourth order rotational symmetry a preferred direction is defined which can be adjusted particularly easily to a corresponding preferential direction of the dipole structure.

In an alternative embodiment the holding device can also have an odd numbered order of rotational symmetry.

The holding device can comprise straight holding struts. Such a holding device can be produced simply on the one hand and enables on the other hand a stable but largely non-interfering arrangement of the obscuration stop in the projection optics. Preferably, the holding device comprises at least two, in particular four straight holding struts. In this way an unwanted rotation of the obscuration stop about an axis perpendicular to the axis of symmetry of the holding device is avoided. A larger number of holding struts is also possible. The obscuration stop can be designed to be circular. This enables the obscuration, i.e. the dimming, of a specific part of the projection beam bundle with a predefined angle of incidence distribution. In particular, but not exclusively for arrangements of the obscuration device, in which the obscura- tion stop is arranged not exactly perpendicular to the direction of the main beam of the central object field point, it can be advantageous to design the obscuration stop to be oval, in particular elliptical.

For rotationally symmetrical systems the deviation from the circular shape is in the region of < 10 % , in particular < 1 %. The ratio of the two main axes of a "best- fit-ellipse" is therefore in the region of 0.9 to 1.1. For systems with free shape surfaces deviations of up to 50 % can be provided, i.e. the long main axis of the best-fit-ellipse is twice as long as the short main axis.

According to claim 3 the obscuration device is arranged in a holding position in the area of a pupil plane in the image beam path in the projection optics. This enables a field-independent pupil obscuration. A field- independent pupil obscuration is particularly advantageous as in this way the dependency of the resolution ability of the projection objective on the details of the illuminating field in particular on the field position is avoided.

Advantageously, the obscuration device is replaceable. This enables a par- ticularly simple adjustment of the obscuration device to the lighting setting.

According to an advantageous embodiment the obscuration device is ro- tatable about an axis parallel to the projection direction. This also enables a particularly simple adjustment of the obscuration device to the lighting setting.

According to claim 4 the projection optics comprises at least one seg- mented mirror with a plurality of mirror segments, wherein the previously mentioned obscuration of the projection optics is formed by at least one intermediate space between the segments of said segmented mirror.

According to claim 5 it is also possible to adjust the lighting setting to a predefined form of the holding device. In this case the lighting setting is designed in particular such that the intensity distribution of the lighting setting in the areas on which the holding struts of the holding device run, is smaller than a predetermined limit intensity I _]im . In this case the limit intensity Ii _im is less than 50% of the maximum intensity I _max of the lighting set- ting at the holding position, in particular less than 30 % of I _max , in particular less than 10 % of I _max , in particular less than 5 % of I _max , in particular less than 1 % of I _max . The areas in which the intensity distribution of the lighting setting is smaller than Ii _im overlap by at least 95 %, in particular at least 99 % of the areas covered by the holding struts of the holding device. In other words the area of the holding struts lies by at least 95 %, in particular at least 99 % - i.e. almost completely, in particular completely - in the area in which the lighting intensity is smaller than the limit intensity. It is particularly advantageous if the areas in which the intensity distribution of the lighting setting is smaller than the limit intensity Iii _m completely cover the areas covered by the holding struts of the holding device or by the intermediate space between the mirror segments. Such an adjustment of the holding device and the lighting setting to one another leads to a particularly low loss of the radiation contained in the lighting setting owing to an unwanted obscuration by the holding device. Preferably, in particular the 0 order of diffraction and/or the + 1 st and - 1 st order of diffraction of the image of the lighting setting in the holding position is arranged at least largely non-overlapping with the areas in which the holding device is arranged. Largely non-overlapping is defined here to mean that at most 10 % of the radiation contained in the 0 and/or the 1st and -1st order of diffraction of the image of the lighting setting fall on the holding struts of the holding device and form a loss. The loss is in particular at most 1 %, in particular 0 %.

According to claim 6 the adjustment of the lighting setting to the holding device can be achieved by a specific arrangement of the illuminated facet elements on the at least one facet mirror.

The illuminated facet elements on the facet mirror can in particular be arranged such that the image of the lighting setting in the pupil plane has ra- diation-free areas for the arrangement of the holding device of the obscuration device, wherein the radiation- free areas in particular of the obscuration stop extend in a straight line, radially to the projection direction at least up to an outer edge of an aperture of the projection optics. This can be achieved in particular in that a specific channel assignment is provided be- tween the field and pupil facets, such that only specific facets of the pupil facet mirror are illuminated, the images of which in the pupil plane do not overlap with the areas for the arrangement of the holding device of the obscuration device. According to claim 7 the lighting optics has a shadowing element for shading the lighting setting, by means of which the lighting setting is adjusted to the form of the holding device of the obscuration stop. This leads to a slight reduction in the radiation available for the projection of the lighting field, however enables a particularly simple adjustment of the lighting settings to the design of the holding device. In addition, in this way an unwanted disruption of the radiation in the projection beam path by the holding device is avoided. A further objective of the invention is to provide a projection lighting system with the optical system according to the invention, a method of producing a micro- or nanostructured component by using such a projection lighting system, as well as a component produced by means of the method. Said objectives are achieved according to the invention by a projection lighting system according to claim 8, a method of production according to claim 10 and a component according to claim 13.

The advantages of these subject matters correspond to those already been discussed above with reference to the optical system according to claims 1 to 7.

A further objective of the invention is to improve a method for adjusting a lighting setting of a projection lighting system.

The objective is achieved by means of the features of claim 9. The essence of the invention is to determine within a predefined lighting setting the light channels, the radiation of which would lead to a worsening of the image quality, and then to modify at least a portion of said light channels. In particular, the group of light channels is determined, the radiation of which overlaps by a predetermined minimum amount in at least one predetermined order of diffraction with an obscuration of the projection optical system when a given structure of a reticle is projected into the image plane of the projection optics, and to modify at least one portion of said light channels, such that this portion after the modification is non-overlapping relative to the obscuration.

In this case the 0 and/or 1st and/or -1st and/or higher orders of diffraction can be taken into consideration. In particular, all of the orders of diffraction of the image of a light channel can be taken into consideration.

In addition, during the modification of the lighting setting more advantageously reticles with specific structures, in particular with one or more pre- determined linear spacings, can be taken into consideration.

Exemplary embodiments of the invention are explained in more detail in the following with reference to the drawings. Figure 1 shows schematically a meridional section through a projection lighting system for EUV projection lithography,

Figures 2a to 4e show schematic representations of several obscuration devices according to the invention, wherein to clarify the concept of the invention images of the 0, 1 st and -1st order of diffraction of typical lighting settings are shown in the region of the pupil plane in the image beam path in the projection optics by way of example, Figures 5 a to c show a schematic representation of the image of the lighting setting in the region of the holding position of the obscuration device and an exemplary representa- tion of the adjustment of the lighting setting on the holding device,

Figure 6 shows a schematic representation of an exemplary embodiment of the projection optics of an additional ex- emplary embodiment of an optical system for a projection lighting system according to Figure 1.

Figures 7a to c show schematic representations of different embodiments of a segmented mirror of the projection optics,

Figure 8a shows a schematic representation of an exemplary reticle,

Figure 8b shows a schematic representation of the diffraction images of the orders of diffraction created by the reticle according to Figure 8a of an exemplary light channel of a lighting setting in the region of the segmented mirror, Figure 8c shows the intensity distribution of the radiation of the light channel shown by way of example in Figure 8b in the region of the segmented mirror, Figures 9a to c show schematic representations according to Figures 8a to c with a different reticle and a different light channel, Figures 10a to c show a schematic representation according to Figures

8a to c with a different reticle and a different light channel,

Figure 11a shows a schematic representation of a segmented

ror according to Figure 7a,

Figure 1 lb shows a schematic representation of the image of an exemplary, non-modified, lighting setting in the region of the mirror according to Figure 1 1a,

Figure 11c shows a schematic representation of the lighting setting according to Figure 1 lb after the adjustment thereof to the form of the mirror according to Figure 1 1a,

Figure l id shows a schematic representation of the image-side contrast for different reticle structures in a lighting setting according to Figure l ib,

Figure 1 le shows a representation according to Figure 1 1 d for a lighting setting according to Figure 1 lc,

Figure 12a shows a schematic representation of a reticle with tical structures, Figure 12b shows a schematic representation of a reticle according to Figure 12a but with horizontal structures, Figure 12c shows a schematic representation of a lighting setting, which is adjusted both to the structures of the reticle according to Figure 12a and also the structures of the reticle according to Figure 12b, Figure 13a shows a schematic representation of a non-adjusted annular lighting setting,

Figure 13b shows a representation of the lighting setting according to Figure 13a after the adjustment to the design of a segmented mirror according to Figure 7b, wherein only the 0 order of diffraction of the image of the lighting setting has been taken into consideration,

Figure 13c shows a representation according to Figure 13b,

wherein in addition to the 0 order of diffraction, the first orders of diffraction for a reticle with a linear spacing which is twice as large as the critical dimension have been taken into consideration,

Figure 13d shows a representation according to Figure 13c for a reticle with a linear spacing which is three times as large as the critical dimension and Figure 14 shows a representation of the image-side contrast for the lighting setting according to Figures 13a to d for reticles with a different linear spacing. Figure 1 shows schematically in a meridional section a projection lighting system 1 for microlithography. A lighting system 2 of the projection lighting system 1 has in addition to a radiation source 3 a lighting optics 4 for illuminating an object field 5 in an object plane 6. In this case a reticle 7 arranged in the object field 5 is illuminated, which is held by a reticle holder 8 shown simply in sections. A projection optics 9 is used for displaying the object field 5 in an image field 10 in an image plane 1 1. A structure on the reticle 7 is displayed on a light-sensitive layer of a wafer 12 arranged in the area of the image field 10 in the image plane 1 1, which wafer is held by an also schematically shown wafer holder 13.

The radiation source 3 is an EUV radiation source with an emitted useful radiation in the region of between 5 nm and 30 nm. This may be a plasma source, for example a GDPP source (Gas Discharge Produced Plasma) or an LPP source (Laser Produced Plasma). Also a radiation source based on a synchrotron can be used as the radiation source 3. A person skilled in the art can find information on such a radiation source for example from US 6,859,515 B2. EUV radiation 14, which comes from the radiation source 3, is bundled by a collector 15. After the collector 15 the EUV radiation 14 propagates through an intermediate focal plane 16 before it hits a field fa- cet mirror 17. The field facet mirror 17 is arranged in a plane of the lighting optics 4, which is conjugated optically relative to the object plane 6.

The EUV radiation 14 is also referred to in the following as an illuminating light or as a display light. After the field facet mirror 17 the EUV radiation 14 is reflected by a pupil facet mirror 18. The pupil facet mirror 18 is arranged in a pupil plane of the lighting optics 4, which is optically conjugated to a pupil plane of the pro- jection optics 9. By means of the pupil facet mirror 18 and a displaying optical component in the form of a transfer optics 19 with mirrors 20, 21 and 22 in the sequence of the beam path field facets of the field facet mirror 17 are displayed in the object field 5. The last mirror 22 of the transfer optics 19 is a grazing incidence mirror. The pupil facet mirror 18 and the transfer optics 19 form following optics for transferring the illuminating light 14 into the object field 5. The transfer optics 19 can be omitted in particular if the pupil facet mirror 18 is arranged in an entry pupil of the projection optics 9. The field facet mirror 17, the pupil facet mirror 18 and possibly the mirrors 20, 21 and 22 of the transfer optics 19 are components of the lighting optics 4. The lighting optics 4 is thus designed to be at least partly reflective, in particular purely reflective, catoptric. To simplify the description of relative positions in Figure 1 a Cartesian xyz coordinate system is included. The x-axis runs in Figure 1 perpendicularly to the plane of the drawing into the latter. The y-axis runs to the right. The z-axis runs downwards. The object plane 6 and the image plane 1 1 both run parallel to the xy-plane.

The reticle holder 8 can be displaced in a controlled manner, so that during the projection lighting the reticle 7 can be displaced in a displacement direction in the object plane 6 parallel to the y-direction. Accordingly, the wafer holder 13 can be displaced in a controlled manner so that the wafer 12 can be displaced in a displacement direction in the image plane 1 1 parallel to the y-direction. In this way the reticle 7 and the wafer 12 can be scanned on the one hand by the object field 5 and on the other hand by the image field 10. The displacement direction is also referred to in the follow- ing as the scan direction. The displacement of the reticle 7 and the wafer 12 in scan direction can preferably be performed synchronously to one another.

The field facet mirror 17 comprises a plurality of field facets 23 indicated only schematically in Figure 1. The field facets 23 are elongated, in particular rectangular or also ring segment-shaped. They have an aspect ratio of at least 1 :2, in particular at least 1 :3, in particular at least 1 :5. The aspect ratio of the field facets 23 corresponds essentially to the aspect ratio of the object field 5. By means of the field facets 23 the radiation 14 from the ra- diation source 3 is broken down into a plurality of radiation bundles. The field facets 23 are used for generating secondary light sources, as each field facet 23 displays the light source 3 or an intermediate focus generated by the collector 15 on a pupil facet 24 assigned to the field facets 23. The field facets 23 in turn are displayed superimposed by means of the facets 24 of the pupil facet mirror 18 in the object plane 6.

The field facets 23 are arranged on the field facet mirror 17 such that its image in the object plane 6 runs respectively parallel to the x-, i.e. to the cross scan direction. This means that with the projection of the field facets 23 in the object plane 6 the long side of each facet runs parallel to the x-, i.e. the cross scan direction, whereas the short side of each field facet 23 points in y-, i.e. in scan direction. To each field facet 23 of the field facet mirror 17 a pupil facet 24 of the pupil facet mirror 18 is assigned. Between a field facet 23 and a pupil facet 24 a light channel is formed. In this case the arrangement of the pupil facets 24 on the pupil facet mirror 18 determines the light distribution, i.e. the lighting setting 25 in the outlet pupil of the lighting optics 4.

The field facets 23 are thus used together with pupil facets 24 of the pupil facet mirror 18, which are also represented only schematically in the drawing, to generate a defined lighting setting 25 for lighting and illuminating the object field 5. In particular, the field facets 23 can also be designed to be switchable, in particular tiltable, in order to enable a light-loss free change of the lighting setting 25. Different channel assignments between the field and pupil facets 23, 24 correspond to different tilting angles of the field facets 23. In particular, it is also possible to select a tilting angle of a field facet 23 so that the illuminating light of said illuminating channel contributes not only to the lighting of the reticle 7 , but for example is deflected onto an light trap. This can e.g. be useful for homogenising the field lighting in the object plane 6. The EUV radiation 14 from the radiation source 3 is collected by means of the collector 15 and converted into a parallel or convergent light bundle. The latter is broken down by means of the field facets 23 into a plurality of partial light bundles, which close to or at the site of the pupil facets 24 form secondary light sources respectively. Said secondary light sources are displayed by the transfer optics 19 in the outlet pupil of the lighting optics 4, which coincides with the entry pupil of the projection optics. The display of the secondary light sources in the outlet pupil plane of the lighting optics 4 thus forms tertiary light sources in the entry pupil plane of the projection optics 9. The projection optics 9 comprises several, in particular at least four, in particular at least five, in particular at least six, in particular at least seven, in particular at least eight projection mirrors or projection mirror elements. The projection optics 9 can in particular be designed to be purely reflectively catoptric. For further details on the projection optics 9 reference is made to WO 2006/069725 Al.

The projection optics 9 comprises one or more pupil planes 26. The term pupil plane in this case defines the totality of the points adjoining one another in a direction perpendicular to a projection direction 27 at which radiation bundles coming from a pupil facet 24 intersect.

In the projection optics system according to the invention at least one pupil plane 26 coincides with none of the mirrors of the projection optics 9.

In the following details of a first embodiment of the projection optics 9 according to the invention are described. The projection optics 9 comprises an obscuration device 28 with an obscuration stop 29 and a holding device 30 for the arrangement of the obscuration stop 29 in the projection optics 9. The holding device 30 forms an obscuration in the projection optics 9. Unlike the obscuration stop 29 the obscuration formed by the holding device 30 is structurally necessary, but does not lead as a rule to a specific improvement of the optical properties of the projection optics 9, but can lead to an unwanted obscuration of a proportion of the illuminating light 14.

The obscuration stop 29 is used for obscuring a portion of the radiation 14 used for displaying the object field 5 in the image field 10. By means of the obscuration stop 29 in particular a defined shadowing of the radiation used for the projection of the object field 5 is possible. The obscuration stop 29 is designed as an inverted perforated stop. It is preferably designed to be circular. However, it can also be designed to be oval, in particular ellipti- cal. This can be advantageous in particular in an arrangement of the obscuration stop 29 transverse but not exactly perpendicular to the direction of the main beam of the central object field point.

The obscuration stop 29 has in particular an aspect ratio, defined by the ratio of the two main axes of a best-fit ellipse, in a range of from 0.9 to 1.1, in particular in a range from 0.99 to 1.01. In the case of an optical system with free form surfaces the aspect ratio can lie in the range of 0.5 to 2.0.

The obscuration stop 29 is made from a material, which absorbs the EUV radiation 14 hitting the latter from the radiation source 3 up to at least 90 %, in particular at least 99 %, in particular completely absorbs it. The obscuration stop 29 is made at least partly, in particular completely, from a material with good thermal conductivity, in particular metal. Preferably, also the holding device 30 is made at least partly, in particular completely, from a material with good thermal conductivity, in particular metal. In this way unwanted heating of the obscuration stop 29 can be avoided, and the thermal influence of adjacent elements, in particular mirrors, of the projection optics system 9 is reduced, in particular avoided. Alternatively or in addition to this the obscuration stop 29 can also comprise a non-reflecting, i.e. an absorbing coating for the EUV radiation 14 from the radiation source 3. The obscuration stop 29 thus blocks the EUV radiation 14, which hits it with a component in projection direction 27. Alternatively or in addition to this the obscuration stop 29 can also have a non-reflecting, i.e. an absorbing coating for radiation of non- EUV wavelengths of the radiation source 3. Particularly for infrared light, which for example exits from a CO2 laser pumped LPP source, or for light in the DUV range this may be advisable or even necessary. The holding device 30 has a second order rotational symmetry. It comprises an outer holding ring 31 and an inner holding ring 32. The inner holding ring 32 is connected by holding struts 33 to the outer holding ring 31. It is also possible to connect the holding struts 33 directly to the obscuration stop 29. In this case the inner holding ring 32 can be omitted. Accord- ing to the exemplary embodiment shown in Figures 2a and 2b the holding device comprises four holding struts 33. The holding struts 33 are designed in particular to be straight. Two of the holding struts 33 respectively are arranged opposite one another in relation to the obscuration stop 29, in a common direction.

In the exemplary embodiment shown in Figures 2a and 2b the holding struts 33 are not distributed evenly over the circumference of the holding rings 31, 32. To each of the holding struts 33 respectively thus an additional holding strut 33 is arranged at a first angle bl < 90° and an addi- tional holding strut 33 is arranged at a second angle b2 > 90°. In particular b2 : bl > 1.5, in particular b2 : bl > 2, in particular b2 : bl > 2.5. The holding device 30 shown in Figures 2a and 2b thus comprises a second order but not a fourth order rotational symmetry. The projection optics 9 comprises an aperture in the region of the position, in which the obscuration stop 29 is arranged, i.e. in the region of the holding position of the obscuration stop 29. The projection optics 9 comprises an aperture in particular in the pupil plane, in which the obscuration stop 29 is arranged. The outer holding ring 31 has an inner diameter, which in particular is greater than the aperture of the projection optics 9. In principle, the outer holding ring 31 can also be designed to have a smaller inner diameter. In this case it functions in addition as an aperture stop. The obscuration stop 29 has a radial dimension of at most 60 %, in particular at most 50 %, in particular at most 40 %, in particular at most 30 %, in particular at most 20 %, in particular at most 10 % of the dimensions of the aperture of the projection optics 9 in the region of the pupil plane 26. To enable a large number of structures to be displayed and/or settings, an ob- scuration of less than 30 % is advantageous. However, it is also possible to design systems with a larger obscuration, which then can only display a limited area of structures.

In the pupil plane 26, in particular in the region of the holding position of the obscuration stop 29, the lighting setting 25 has an intensity distribution with a maximum intensity I _max . In this case for the intensity of the lighting setting 25 in particular the intensity of the images of the 0 order of diffraction 34 and the 1st and -1st order of diffraction 35 can be taken into consideration. In particular, the images of all orders of diffraction can be taken into consideration. It is also possible however to take into consideration only the images of individual orders of diffraction, in particular the images of the 0 order of diffraction 34 or the 1st and -1st order of diffraction 35 or higher orders of diffraction. It is also possible to consider the lighting setting 25 as a whole or to consider individual light channels of the lighting setting 25 separately from one another.

Figure 2a shows a Y dipole lighting setting 25, wherein for clarification the images of the 0 order of diffraction 34 and the 1st and -1st order of diffraction 35 are shown schematically. The dipole Y lighting setting 25 is charac- terised in that the image of the light sources in the pupil plane 2 comprises areas spaced apart in y-direction and opposite one another relative to the main beam of the central object field point. The areas are designed in particular to be mirror symmetrical to the main beam of the central object field point. The images of the orders of diffraction 35 are generated by diffraction on horizontal and vertical structures of the reticle 7 in the object field 5.

According to the invention the holding device 30 and the lighting setting 25 are adjusted to one another, such that the area in which the intensity of the lighting setting 25 is greater than a limit intensity l _Vltn , and the holding device 30 are non-overlapping. In this case in particular Ι _Ηηι < 0.1 I _max . Of course, a different limit intensity I _lim can also be selected. In particular Ii _im < 0.5 I _max , in particular Ii _im < 0.3 I _max , in particular I _lim < 0.1 I _max , in particu- lar Ii _im < 0.05 I _max , in particular I _lim < 0.01 I _max , in particular I _lim < 0.001

For the adjustment of the holding device 30 and the lighting setting 25 to one another, in particular the arrangement of the holding struts 33 can be adjusted to the specific details of the intensity distribution of a specific lighting setting 25. For example for different lighting settings 25 in combination with specific structures to be displayed specifically adjusted holding devices 30 can be provided. The obscuration device 28 is designed in particular to be replaceable. Alternatively to or in addition thereto the holding device 30 can also be designed to be adjustable, in particular rotatable. In this case the holding device 30 can be adjusted by simple rotation from a Y dipole lighting setting 25, as shown in Figure 2a, to an X dipole lighting setting 25, as shown in Figure 2b. In Figures 3a to 3d an alternative embodiment of an obscuration device 36 is shown. In this case the holding device 30 is adjusted to a lighting setting 25 with a quadrupole structure. The holding device 30 comprises four holding struts 33. Unlike the holding device 30 according to Figures 2a and 2b the holding struts 33 are arranged distributed evenly around the circumference of the holding rings 31, 32. The holding device 30 according to Figures 3a to 3d thus has a fourth order rotational symmetry.

The holding device 30 can be rotated about an axis parallel to the projec- tion direction 27 to adjust to the type of quadrupole, in particular to adjust to a so-called C-quad, as shown in Figure 3a, or to a quasar, as shown in Figures 3b to 3d.

As above, the areas in which the intensity of the lighting setting 25 is grea- ter than the limit intensity Ii _im , and the holding device 30 are non- overlapping.

A further design of an obscuration device 37 is shown in Figures 4a to 4e. The obscuration device 37 comprises only two holding struts 33. In this way the holding device 30 of the obscuration device 37 can be adjusted both to lighting settings 25 with a dipole structure, in particular with any orientation, and also to lighting settings 25 with a quadrupole structure, in particular with any orientation. The holding device 30 of the obscuration device 37 has a second order but not a fourth order rotational symmetry.

A further option of how the holding device 30 and the lighting setting 25 can be adjusted to one another in combination with specific structures to be displayed, is illustrated in Figures 5a to 5c. With a completely annular lighting setting 25 if necessary a portion of the EUV radiation 14 of the lighting setting 25 hits the radially arranged holding struts 33. In order to reduce the worsening of the image quality, the lighting setting 38 can be adjusted to the formation of the obscuration formed by the holding device 30. In this case in particular it is provided that, to adjust the lighting setting 38 to the predetermined design of the holding device 30, so that the intensity distribution of the lighting setting 38 on the holding position of the obscuration device 37 in the areas, in which the holding struts 33 of the holding device 30 run, is smaller than the previously defined limit intensity I _lim . For this purpose for example an annular setting, as shown in Figure 5 a, can be replaced by a slotted annular setting, as shown in Figure 5b.

To adjust the lighting setting 38 on the one hand a specific arrangement of pupil facets 24 can be provided on the pupil facet mirror 18. In this case on the pupil facet mirror 18 in particular facet-free areas are designed and arranged, such that the image of the lighting setting in the pupil plane 26 largely has largely radiation-free areas for the arrangement of the holding device 30. Largely radiation-free areas are defined in this case to be areas in which the intensity of the lighting setting 38 is smaller than the limit intensity Ii _im . Said largely radiation-free areas extend in particular in a straight line from the obscuration stop 29, radially to the projection direction 27, up to the outer holding ring 31. To adjust the lighting setting 38 also a switchable illumination of the pupil facets 24 of the pupil facet mirror 18 can be provided. In particular, the facets of the field facet mirror 17 can be designed to be switchable. In this case the assignment of the field facets 23 to the pupil facets 24 can be adjusted. To enable a loss-free adjustment of the lighting setting 38, the facets 23 of the field facet mirror 17 can be designed to be switchable, so that the latter deflect the incidental light onto a suitable pupil facet 24 of the pupil facet mirror 18. A suitable pupil facet 24 is defined in this case as a pupil facet 24, which is arranged on the pupil facet mirror 18 such that the image of the corresponding light channel, in particular the 0 order of diffraction 34 and/or the 1st and/or -1st order of diffraction 35 and/or higher orders of diffraction thereof is non-overlapping with the obscuration, in particular with the holding device 30.

Lastly, it is possible for the adjustment of the lighting setting 38 to the design of the holding device 30 to provide a shadowing element 39 in the lighting optics 4. In other words the lighting optics 4 in this case comprises the shadowing element 39 for shading the lighting setting 38, wherein by means of the shadowing element 39 the lighting setting 38 is adjusted to the design of the holding device 30 of the obscuration device 28, 37.

The shadowing element 39 can in particular be arranged in the beam path between the pupil facet mirror 18 and the transfer optics 19, in particular the mirror 20. The shadowing element 39 is more advantageously arranged such that it is crossed exactly once by the beam path in the lighting optics 4. It can also be advantageous to arrange the shadowing element 39 in the vicinity of the pupil facet mirror 18.

In the following with reference to Figures 6 to 14 further exemplary embodiments of the invention are described. Identical parts have been given the same reference numbers as in the preceding described embodiments, the description of which is referred to here. The projection optics 9 shown in Figure 6 comprises six mirrors Ml to M6. A different number of mirrors for the projection optics 9 is also possible. The projection optics 9 can in particular comprise at least four mirrors. It can for example also comprise eight mirrors. The last mirror M6 in the beam path 40 is designed in the form of a segmented mirror. It comprises several mirror segments 41. The mirror segments 41 are separated from one another by intermediate spaces 42.

In principle also one or more of the other mirrors Ml to M5 of the projection optics 9 can be designed to be segmented. For the remaining description the segmented mirror is denoted by the reference number 43. In particular with large mirrors a segmented design can be advantageous or even necessary. A segmented design has essential manufacturing advantages. For example, the maximum diameter to be processed in a segmented mirror is much lower than in a corresponding unsegmented mirror. Furthermore, the individual segments have a much lower mass and can therefore be designed to be thinner. In this way in particular also the gravitation- determined reformation of the mirror segments 41 is reduced. Segmenting is advantageous in particular for mirrors with a diameter of more than 30 cm, in particular more than 40 cm, in particular more than 50 cm.

As a rule the last mirror M6 of the projection optics 9 is the largest and thus the first at which a division into segments 41 can be necessary. The larger the last mirror M6, the larger the image-side numeral aperture of the projection optics 9 can be. A larger numerical aperture leads to an increase in the resolution ability. The image-side numerical aperture of the projec- tion optics 9 is in particular at least 0.2, in particular at least 0.3, in particular at least 0.4.

The segmenting of the last mirror M6 in front of the wafer 12 is translated one to one into a segmenting of the possible light incidental directions on the wafer 12, i.e. a segmenting of the pupil. The segmenting is in other words tantamount to shadowing in the region of the segmented mirror M6. In other words, the first obscuration of the projection optics 9 in this exemplary embodiment is formed by the intermediate space 42 or the intermedi- ate spaces 42 between the mirror segments 41 of the segmented mirror M6.

The segmented mirror M6 can be arranged in particular close to the pupil. In this way the dependency of the resolution ability of the projection objective on the details of the lighting field, in particular on the field position, is avoided.

Figures 7a, 7b and 7c show by way of example three embodiments of the segmented mirror 43. The mirror 43 has a diameter D of 80 cm. In particular, it has a diameter D of at least 40 cm, in particular at least 60 cm. The mirror 43 can also have a different diameter. It has a circular circumference. It can also have a circumference that differs from the circular shape. The mirror 43 shown in Figure 7a comprises four mirror segments 41. The mirror segments 41 are separated from one another by the intermediate space 42. The intermediate space 42 has a width b in the region of 1 mm to 10 cm, in particular in the region of 5 mm to 5 cm. The width b can be con- stant over the extension of the intermediate space 42. It can also be variable over the extension of the intermediate space 42.

In the exemplary embodiment shown in Figure 7a the intermediate space 42 extends radially in sections from a middle point 44 of the mirror 43, in a straight line to its circumference. The four mirror segments 41 of the mirror 43 have an identical outer circumference. The mirror segments 41 are designed to be in the form of sectors of a circle. The mirror segments 41 each comprise a middle point angle t of 90°. The middle point angle t can also be slightly smaller than 90°. It is in particular in the region of 85° to 90°.

The mirror segments 41 are held by a holding device not shown in the Figures. The holding device can be arranged at least partly in the region of the intermediate space 42.

The mirror 43 according to Figure 7a has a fourth order rotational symmetry.

According to the embodiment shown in Figure 7b the mirror 43 has six mirror segments 41. The mirror segments 41 have a central angle t of 60°. The central angle t lies in particular in the region of 55° to 60°. The mirror 43 according to Figure 7b has a sixth order rotational symmetry. Furthermore, reference is made to the description of the mirror according to Figure 7a.

According to the embodiment shown in Figure 7c the mirror 43 comprises seven mirror segments 41. In this case the segments 41 have a central, hexagonal mirror segment 41 and six rectangular outer mirror segments 41, surrounding said central mirror segment 41. The outer mirror segments 41 have respectively a circumference which is composed of three straight sections and a circular arc-shaped section. The segmentation of the mirror 43 according to Figure 7c corresponds directly to a circular section of a regular hexagonal parquetted plane.

According to the embodiment shown in Figure 7c the mirror 43 in the region around its middle point 44 has an uninterrupted mirror surface formed by the central mirror segment 41. The mirror 43 thus has no central obscuration.

The mirror 43 shown in Figure 7c has a sixth order rotational symmetry. Alternative segmentations of the mirror 43 are also possible. In the following with reference to the Figures 8a to 8c, 9a to 9c and 10a to 10c possible effects of the obscurations of the mirror 43 formed by the intermediate spaces 42 are explained by way of example. In Figure 8a a reticle 7 is shown by way of example, the structure 45 of which is formed by a plurality of linear, vertically running elements 46. The structure 45 corre- sponds to the structure of a diffraction grid. The linear elements 46 are arranged to be equidistant to one another. They have a linear spacing 1. The distance between two line central points, i.e. twice the linear spacing 1, is also denoted as the pitch. The linear spacing 1 is usually in the region of 10 nanometres to 1000 nanometres, in particular in the region of 20 nano- metres to 500 nanometres.

In Figure 8b the position of the images of the 0 order of diffraction 34 and the -1st order of diffraction 35 of a specific light channel of the lighting setting 25 is shown. Whilst the position of the 0 order of diffraction 34 is independent of the structure 45 of the reticle 7, in particular independent of the linear spacing 1 thereof, the position of the higher orders of diffraction is dependent on the structure 45 of the reticle 7 in particular on the linear spacing 1 of the linear elements 46.

In the example shown in Figure 8b the 0 order of diffraction 34 falls straight onto the obscuration formed by the intermediate space 42 between two mirror segments 41 of the segmented mirror 43. This leads to a loss of transmission of the projection optics 9. In this example also the -1st order of diffraction 35 falls onto the intermediate space 42 between two mirror segments 41. Also this order of diffraction is thus not available for a display of the reticle 7 in the image plane 1 1. Higher orders of diffraction and the 1st order of diffraction fall outside the numerical aperture of the projection optics 9. They can thus also not contribute to the display of the reticle 7 in the image plane 1 1. The intensity distribution in the image plane 1 1 shown in Figure 8c and belonging to this light channel is thus identical to the 0 radiation of this light channel and is completely lost between the mirror segments 41. Figures 9a to 9c show by way of example a corresponding situation for a different light channel and a different structure 45. The reticle 7 comprises in this case a structure 45 with a greater linear spacing 1.

In Figure 9b the 0 order of diffraction 34 and the -1st and +lst order of dif- fraction 35 of a central light channel of the lighting setting 25 is shown. In this example the 0 order of diffraction 34 falls on the intermediate space 42. The -1st and +lst order of diffraction 35 falls on a mirror segment 41 and thus contributes to the display of the structure 45 of the reticle 7 in the image plane. This leads to the intensity distribution shown in Figure 9c. In this case an unwanted frequency doubling can be observed. In general terms there is a worsening of the image quality.

Figures 10a to 10c show an additional reticle 7 with a structure 45 and the position of the 0 order of diffraction 34 and -1st / + lst order of diffraction 35 of a decentralised light channel of the lighting setting 25 and an associated intensity distribution in the image plane 1 1. In this example the 0 order of diffraction 34 falls on a mirror segment 41. The -1st order of diffraction 35 falls on the intermediate space 42. The +lst order of diffraction 35 falls outside the mirror 43. As only the 0 order of diffraction 34 contributes to the display of the structure 45, whilst the only possible interference partner, the -1st order of diffraction 35, falls on the intermediate space 42, a contrast-reducing background is formed, i.e. a structureless image of homogeneous intensity in the image plane 1 1. This also leads to an unwanted reduction in the contrast, i.e. a worsening of the image quality of the projection optics 9.

Figure 11a shows again by way of example the mirror 43 according to the embodiment shown in Figure 7a. If the reticle 7 with the structures 45 to be displayed is illuminated by the lighting setting 25 shown schematically in Figure 1 lb in the form of a quasar, a proportion of the illuminating light 14 hits the intermediate space 42. This leads to a reduction in contrast or in general a worsening of the image quality. To measure the image side contrast the so-called NILS value (Normalized Image Logarithmic Slope) is used. The NILS value is defined as follows: wherein I is the intensity and CD (Critical Dimension) is the line width. The NILS value is thus defined as twice the relative intensity change per relative change of the line width. In general, NILS = 1 is seen as the lower limit for a stable lithographic process. Usually, a much higher NILS value, in particular NILS > 1.3, preferably NILS > 1.5 is desirable. In this case loss of contrast of the colour is included in the calculation.

Figure 1 Id shows different curves 47j to 47 _]2 for the path of the NILS value as a function of the width b of the intermediate space 42 for reticles with structures 45 with different linear spacings 1. The curves 471 _{10 )2} relate to reticles 7 with structures 45 with the following linear spacings 1:

As shown in Figure l id, the NILS value for some of the structures 45 from a specific width b of the intermediate space 42 lies between the mirror segments 41 below 1.5, in particular below 1.

Figure 1 lc shows a modified lighting setting 48 based on the lighting set- ting 25 according to Figure 1 lb. The modified lighting setting 48 is designed to be straight such that the areas of the lighting setting 25 according to Figure l ib, i.e. the corresponding light channels, which without diffraction on the structure 45 of the reticle 7, i.e. in the 0 order of diffraction, would hit the intermediate space 42, have been cut out of the lighting set- ting 25. The modified lighting setting 48 is thus adjusted to the obscuration of the segmented mirror 43 formed by the intermediate space 42. The modified lighting setting 48 is adjusted in particular to the obscuration of the segmented mirror 43 such that the 0 order of diffraction 34 of the light- ing setting 48, in particular all of the light channels thereof, is non- overlapping with the intermediate space 42. As shown in Figure 1 le, this adjustment of the lighting setting 25 leads to a significant increase in the NILS value for almost all values of the width b of the intermediate space 42 and almost all linear spacings 1.

With the design of the segmenting of the mirror 43 according to Figure 1 la and the lighting setting 25 according to Figure 1 lb Figures 1 Id and 1 le show diagrams both of structures 45 with vertical, linear elements 46 and of structures 45 with horizontal linear elements 46.

A further example of a modified lighting setting 48 is shown in Figure 12c. The modified lighting setting 48 according to Figure 12c is based on a completely filled lighting setting 25, i.e. a completely filled pupil. All radiation 14 was omitted that had no interference partner in the first order. First of all, areas were removed which owing to the numerical aperture stop have no interference partner. Said lighting setting 48 is adjusted to the two reticles 7 shown in Figures 12a and 12b with vertical or horizontal structures 45 with a linear spacing 1 of 32 nanometres, so that both the 0 and also the -1st and +lst order of diffraction of the image of the lighting set- ting 48 are reflected completely on the mirror 43 according to the embodiment shown in Figure 1 la. Both the 0 order of diffraction 34 and the -1st and +lst order of diffraction 35 of said lighting setting fall completely on mirror segments 41 of the mirror 43. They are non-overlapping with the intermediate space 42. In general, a provided lighting setting 25, which was selected for reticles 7 with specific structures 45 with the assumption of a projection optics 9 with only non-segmented mirrors Ml to M6, i. e. mirrors with a continuous reflection surface, is adjusted to the obscuration of the mirror 43, in particular its intermediate spaces 42 so that the light channels of the lighting setting 25, which were displayed at least partly in the region of the intermediate space 42 are modified such that its image in the region of the mirror 43 does not overlap with the intermediate space 42.

A non-overlapping arrangement is defined in this case as when the intensity of the illuminating light 14 of a specific light channel in the region of the intermediate space 42 is smaller than a predefined limit value I _)im < 0.1 I _max . The limit value l _im can be selected as necessary. In particular I| _im < 0.5 I _max , in particular I _Hm < 0.3 I _max , in particular Ii _im < 0.1 I _max , in particular I _lim < 0.05 I _max , in particular Ii _im < 0.01 I _max . Particularly in the area of the intermediate space 42 it is essentially equal to 0. As already explained by way of example with reference to Figures 8a to 10c specific orders of diffraction or their obscuration can lead to different effects. They can there- fore be taken into consideration especially for the adjustment of the lighting setting 25.

According to one embodiment the arrangement of the pupil facets 24 on the pupil faceted mirror 18 is adjusted to the segmenting of the mirror 43. In particular, in an arrangement of the mirror 43 in a pupil plane of the projection optics the segmenting of the mirror 43 apart from a possible scaling can be transferred essentially identically to the arrangement of the pupil facets 24 onto the pupil facet mirror 18. In this way it can be ensured that in any case the 0 order of diffraction 34 of a lighting setting 25 generated by the pupil facet mirror 18 does not overlap with the intermediate space 42 of the segmented mirror 43.

In the following with reference to Figures 13a to 13d and 14 the adjustment of the lighting setting 25 to the design of the segmented mirror 43, in particular the arrangement of the intermediate space 42 between the mirror segments 41 is explained by way of example. In this exemplary embodiment a 6-fold segmented mirror 43 according to the embodiment shown in Figure 7b is assumed. The originally provided lighting setting 25 is an an- nular lighting setting. The light channels are arranged in an annular area.

As shown in Figure 13b, firstly the light channels of the lighting setting 25 are determined, the 0 order of diffraction 34 of which falls on the intermediate space 42 of the segmented mirror 43 or overlaps therewith. As the position of the image of 0 order of diffraction 34 is independent of the structure 45 of the reticle 7, the latter need not be taken into consideration here.

Said light channels belong to a first group of light channels, which can lead to a worsening of the image quality, in particular to a reduction in the contrast of the image of the structure 45 of the reticle 7 in the image plane 1 1.

In addition, the light channels are defined, the 1st and/or -1st order of diffraction 35 during the diffraction of the structure 45 of the reticle 7 over- laps with the intermediate space 42 of the segmented mirror 43. Also said light channels are assigned to the first group. As the position of the image of the orders of diffraction with the exception of that at the 0 order of diffraction is dependent on the structure 45 of the reticle 7, in particular on the linear spacing 1 thereof, in this case a selection of structures 45 with different linear spacing 1 can be taken into consideration.

In the shown exemplary embodiment structures with a linear spacing 1 = 2 CD (Fig. 13c) and 1 = 3 CD (Fig. 13d) were taken into consideration, wherein CD = Kl λ/ΝΑ with Kl = 0.53, λ: wavelength of the illuminating light 14 of the lighting setting 25 and NA = 0.45. This corresponds to a wavelength of the illuminating light 14 of 13.6 nanometres, a critical dimension, CD, of 16 nanometres, i.e. a linear spacing of 32 nanometres and 48 nano- metres.

In the modified lighting setting 48 shown in Figure 13c in addition to the light channels, the 0 order of diffraction 34 of which with the intermediate chamber 42 overlaps the light channels from the lighting setting 25, the -1st or 1st order of diffraction 35 of which overlap with the intermediate space 42, on diffraction on a reticle 7 with a structure 45, which has vertical, linear elements 46 with a linear spacing 1 = 2 CD, i.e. 32 nanometres.

Accordingly in the lighting setting 48 shown in Figure 13d in addition the diffraction on a reticle 7 with a structure 45 with vertical linear elements 46 with a linear spacing 1 = 3 CD, i.e. 48 nm, is taken into consideration.

In general the original, predefined lighting setting 25 is modified such that at least one portion of the light channels of the first group after modifica- tion, i.e. in the modified lighting setting 48, in at least one predefined order of diffraction, in particular in the 0 and/or 1st and/or -1st and/or higher order of diffraction, is by at least a prespecified minimum amount non- overlapping with the obscuration formed by the intermediate space 42. In other words there is a modification of at least one portion of the light chan- nels, in particular all of the light channels, which would lead to a worsening of the quality of the image, in particular to a reduction in the contrast of the image of the structures 45 of the reticle 7 in the image plane 1 1. How a modification according to the invention of said light channels can occur is described in more detail below.

As shown with reference to Figures 13a to 13d, the area available overall for the modified lighting setting 48 with increasing consideration of higher orders of diffraction and/or structures 45 decreases more and more with different linear spacings 1. To take this into account according to an advantageous embodiment, on the adjustment of the lighting setting 25 firstly the structure 45, in particular the linear spacing 1, has to be taken into consideration, which with the display in the image plane 1 1 without an adjustment of the lighting setting 25 would have the least contrast. Afterwards, the method can be repeated iteratively, so that in each additional step of the remaining structures 45 the structure with the linear spacing 1 is taken into consideration which in the display in the image plane 1 1 had the least contrast. The adjustment process can be stopped, as soon as the portion of the actually usable lighting and/or the area available overall for the modified lighting setting 48 falls below a predetermined limit value.

Figure 14 shows the effect of the adjustment of the lighting setting 25 according to Figures 13a to 13d. The NILS value for the different lighting settings 25, 48 according to the Figures 13a to 13d is entered against the linear spacing 1. The curves are characterised according to the lighting settings 25, 48 shown in the Figures 13a to 13d. As shown in Figure 14, the cutting of the 0 order of diffraction 34 mainly leads to an improvement of the contrast with larger linear spacings 1. The consideration of the 1st / -1st order of diffraction 35 leads in particular to an improvement in the contrast for structures 45 with a corresponding linear spacing 1 and/or a whole digit multiple thereof.

As the position of the images of the -1st and 1st order of diffraction 35 and the higher orders of diffraction is dependent on the structures 45 of the reticle 7, in particular on the linear spacing 1 of the elements 46 of these structures 45, said structures 45 are considered preferably separately during the adjustment of the lighting setting 25. In this way one or several structures 45 with different linear spacings 1 can be taken into consideration. For ex- ample, it may be sufficient to consider only the structure 45, which would lead without an adjustment of the lighting setting 25 to the least contrast, in particular to the lowest NILS value, during the adjustment of the lighting setting 25. This can be performed in an iterative process. The adjustment process can be continued in particular until all of the critical structures 45 have a sufficiently high contrast, in particular a sufficiently high NILS value, in particular NILS > 1, in particular NILS > 1.3, in particular NILS > 1.5, during the depiction by the projection objective 9. As the total amount of illuminating light 14 usable for the image by modifying the lighting setting 25 is smaller, with such an iterative process the modifica- tion of the lighting setting 25 can be optimised such that the image of a predetermined reticle 7 with specific structures 45 has the best possible contrast, in particular the highest possible NILS value, with at the same time the highest possible total amount of illuminating light 14. For the modification, i.e. adjustment of the lighting setting 25, i.e. for setting the modified lighting setting 48 according to the invention different alternatives are provided. According to a first variant the obscuration formed by the segmenting of the mirror 43 can be taken into account for the arrangement of the pupil facets 24 on the pupil facet mirror 18. For further details reference is made to the preceding description. In this embodiment it can be ensured in particular that the images of the 0 order of diffraction of the light channels are projected without loss into the image plane 1 1. According to a further embodiment the light channels are switched off, the image of which light channels overlaps the intermediate space 42 in at least one predetermined order of diffraction, in particular the 0 and/or -1st and/or +lst order of diffraction, by more than a predetermined maximum amount. For this purpose in particular a controllable lighting optics 4 is provided. For constructive details of a controllable lighting optics 4 by way of example reference is made to DE 100 53 587 Al, respectively US 6,658,084 B2 and DE 10 2010 029 765.8, respectively US 61/352,459.

The predetermined maximum proportion is at most 50 %, at most 30 %, in particular at most 10 % of the total intensity, in particular at most 5 %, in particular at most 1 %.

In a further, advantageous embodiment the light channels to be modified are deflected. For this purpose, facet mirrors 17, 18 with switchable facets 23, 24 are provided. Such an embodiment has the advantage that the total intensity of the modified lighting setting 48 is increased. In an ideal case it can correspond to the total intensity of the original lighting setting 25.

According to a further alternative individual channels can be equipped, i.e. dimmed, by arranging a suitable shadowing element 39 in the lighting optics 4. Reference is made in this regard to the preceding description.

Furthermore, it is conceivable to adjust the modified lighting setting 48 to optimise only the intensity distribution of the individual light channels. This can be achieved in particular in that the individual light channels of the modified lighting setting 48 have different intensities for lighting the reticle 7 with the structures 45. It is conceivable in particular to reduce the intensity of one, several or all of the light channels of the first group from the original lighting setting 25. The intensity of the light channels to be modified can be reduced for example by 10 %, 30 %, 50 %, 70 %, 90 % or 100 %.

Which channels of the originally provided lighting setting 25 belong to the first group, i.e. need to be modified, can be determined in particular by taking into consideration the predetermined structures 45 of a specific reticle 7. This can be performed in particular by computer and/or by means of a simulation. In principle also an experimental determination of the light channels of a predefined lighting setting 25 to be modified is possible.

When using the projection lighting system 1 the reticle 7 and the wafer 12, which has a light-sensitive coating for the illuminating light 14, are provided. Afterwards at least one section of the reticle 7 is projected by means of the projection lighting system 1 onto the wafer 12. During the projection of the reticle 7 onto the wafer 12 the reticle holder 8 and/or the wafer holder 13 can be displaced in a direction parallel to the object plane 6 or parallel to the image plane 1 1. The displacement of the reticle 7 and the wafer 12 can preferably be performed synchronously to one another.

Lastly, the light-sensitive layer lit by the illuminating light 14 is developed on the wafer 12. In this way a micro- or nanostructured component, in particular a semiconductor chip, is produced.