WO2016058826A1

WO2016058826A1 - Radiation source module

Info

Publication number: WO2016058826A1
Application number: PCT/EP2015/072440
Authority: WO
Inventors: Michael Patra
Original assignee: Carl Zeiss Smt Gmbh
Priority date: 2014-10-17
Filing date: 2015-09-29
Publication date: 2016-04-21
Also published as: TW201624145A; DE102014221173A1

Abstract

In a projection exposure system, at least one auxiliary radiation source (32_i) is provided for compensating for fluctuations of a main radiation source.

Description

Radiation source module

The present application claims priority of German patent application DE 10 2014 221 173.5 the content of which is incorporated herein by reference.

The invention relates to a radiation source module for a projection exposure system. The invention furthermore relates to an illumination device and an illumination system for a projection exposure system.

Moreover, the invention relates to a scanner for a projection exposure system, and to a projection exposure system. Finally, the invention relates to a method for producing a micro- or nanostructured component, and to a component produced according to this method. During the exposure of a wafer in a projection exposure apparatus, it is desirable that the radiation dose which reaches the wafer can be controlled very exactly and rapidly. There is therefore a constant need to improve a radiation source module for a projection exposure system and/or an illumination device and/or an illumination system for a projection exposure system, in particular for a projection exposure system comprising a plurality of scanners.

This object is achieved by means of a radiation source module comprising at least one main radiation source and at least one auxiliary radiation source, which serves for compensating for fluctuations of the main radiation source. Fluctuations of the transmission of a scanner can also be compensated for by such a radiation source module. The fluctuations of the main radiation source can be power fluctuations and/or geometrical fluctuations. Geometrical fluctuations should be understood to mean fluctuations of the direction of the illumination radiation emitted by the main radiation source and/or fluctuations of the cross-sectional profile of the illumination radiation emitted by the main radiation source.

Both the at least one main radiation source and the at least one auxiliary radiation source contribute to the illumination of a reticle in an object plane and/or the imaging of the reticle onto a wafer in an image plane.

The at least one main radiation source can be, in particular, a free electron laser (FEL) and/or a synchrotron radiation source. In particular, an EUV radiation source, that is to say a radiation source which emits illumination radiation in the EUV range, in particular in the range of 30 nm or less, in particular 13.5 nm or less, can be involved.

The main radiation source can emit illumination radiation having a radiation power in the range of 100 W to 50 kW, in particular of at least 300 W, in particular of at least 500 W, in particular of at least 1 kW, in particular at least 3 kW, in particular at least 5 kW, in particular at least 10 kW, in particular at least 30 kW. It has been recognized according to the invention that fluctuations of the main radiation source can be compensated for in a simple manner with the aid of at least one auxiliary radiation source. The radiation source module can be used particularly advantageously in a projection exposure system comprising a plurality of scanners. It can be particularly advantageous to assign in each case one or a plurality of auxiliary radiation sources to a specific scanner. In particular, a plurality of auxiliary radiation sources can be provided. In this case, each auxiliary radiation source can be assigned exactly one scanner. It is also possible to assign at least one auxiliary radiation source to each scanner. The main radiation source can advantageously supply a plurality of scanners with illumination radiation.

In accordance with one aspect of the invention, a ratio of the radiation power P_main of the main radiation source to the radiation power P_aux of the auxiliary radiation source is at least 1.5, in particular at least 2, in particular at least 3, in particular at least 5, in particular at least 10, in particular at least 20, in particular at least 30, in particular at least 50, in particular at least 100, in particular at least 200, in particular at least 300, in particular at least 500, in particular at least 1000.

The total radiation power, that is to say the sum of the radiation powers of the auxiliary radiation sources assigned to a specific scanner, can be, in particular, of precisely the same magnitude as the maximum expected fluctuation of the radiation power of the main radiation source.

The radiation power P_aux of the individual auxiliary radiation sources is in particular in the range of 10 mW to 1 kW, in particular in the range of 1 W to 100 W, in particular in the range of 10 W to 30 W.

In accordance with one aspect of the invention, the total power of the auxiliary radiation sources assigned to an individual scanner is at most 10%, in particular at most 5%, in particular at most 3%, in particular at most 1%, of the total power of the illumination radiation fed to said scanner by the main radiation source. The latter results, in particular, from the total power of the at least one main radiation source divided by the number of scanners.

The radiation power P_aux of the individual auxiliary radiation sources is in particular in the range of 0.5% to 10%, in particular in the range of 1% to 3%, of the power of the main radiation source P_mai_n-

In particular, a xenon plasma source is suitable as auxiliary radiation source. A synchrotron radiation source or a plasma source having higher power can also serve as auxiliary radiation source. Gadolinium or terbium can also be used in a plasma source. In this case, it is possible, in particular, for an auxiliary radiation source to be assigned to a plurality of scanners. A further FEL can also serve as auxiliary radiation source. A plurality of FELs can also be provided as auxiliary radiation sources. The FEL can be assigned, in particular, to a plurality of scanners. It is also possible, in particular, to supply a multiplicity of projection exposure systems with illumination radiation by means of two FELs. In this case, the auxiliary radiation source can be embodied identically to the main radiation source.

In accordance with one aspect of the invention, the auxiliary radiation source has a controllable radiation power P_aux. It is also possible for the radiation power which is provided by the auxiliary radiation source at the output of the radiation source module, in particular at the input of a scanner, to be controlled by additional optical elements. The radiation power P_aux used by the auxiliary radiation source for compensating for fluctuations of the main radiation source is controllable, in particular, on a time scale of faster than 1 ms. The radiation power of the auxiliary radiation source for compensating for fluctuations of the main radiation source is controllable in particular depending on at least one parameter of the main radiation source, in particular depending on the emitted radiation power P_main of the main radiation source and/or the direction of the emitted radiation of the main radiation source and/or the divergence of the raw beam emitted by the main radiation source. The radiation power of the auxiliary radiation source is regulatable in particular depending on at least one of these parameters. For this purpose, the radiation source module can comprise in particular one or a plurality of sensors for detecting a suitable parameter, in particular the radiation power and/or the direction and/or the cross section of the illumination beam emitted by the main radiation source.

In accordance with a further aspect of the invention, the radiation source module comprises a plurality of auxiliary radiation sources. The number of auxiliary radiation sources can be in particular at least two, in particular at least three, in particular at least five, in particular at least eight, in particular at least ten, in particular at least twelve, in particular at least sixteen, in particular at least thirty, in particular at least fifty. The number of auxiliary radiation sources can correspond in particular precisely to the number of scanners or to an integral multiple of said number.

In accordance with a further aspect of the invention, the individual auxiliary radiation sources are embodied substantially identically. In accordance with a further aspect of the invention, the at least one main radiation source and the at least one auxiliary radiation source are arranged in the beam path of the illumination radiation on different sides of an output coupling optical unit.

The at least one auxiliary radiation source emits illumination radiation in the same wavelength range as the main radiation source, in particular in the EUV range, in particular in the range of 30 nm or less, in particular 13.5 nm or less.

The object according to the invention is additionally achieved by means of an illumination device comprising at least one auxiliary radiation source for compensating for fluctuations of a main radiation source. For embodying the illumination device it suffices if the properties of a main radiation source to be provided, in particular the radiation power thereof and the maximum expected fluctuations of said radiation power, are known. These properties can also be predefined as requirements made of the main radiation source.

In accordance with a further aspect of the invention, the illumination device comprises at least two object fields, in which a reticle can be arranged and illuminated, wherein each object field can be illuminated by at least one auxiliary radiation source, and each auxiliary radiation source illuminates a maximum of one object field.

The object is additionally achieved by means of an illumination system comprising a radiation source module according to the description above and by means of an illumination system comprising an illumination device according to the description above.

The illumination system comprises, besides the radiation source module, at least one beam guiding optical unit for transferring illumination radiation into a reticle plane. The illumination system can comprise in particular a plurality of such beam guiding optical units.

Proceeding from the illumination device, the illumination system

additionally comprises at least one main radiation source.

In accordance with a further aspect of the invention, the at least one auxiliary radiation source is in each case part of a control loop. The control loop comprises in particular an energy sensor for detecting the radiation energy or radiation power fed to a specific scanner, in particular to a given object field. The energy sensor can be arranged in particular in or in proximity to the reticle plane.

The energy sensor and thus the control loop is scanner-specific, in particular. A separate control loop is provided in particular for each of the scanners.

In accordance with one aspect of the invention, the main and auxiliary radiation sources are embodied and/or arranged in such a way that they illuminate different regions, in particular different facets, of a first and/or second facet element of an illumination optical unit. The at least one main radiation source and the at least one auxiliary radiation source can illuminate in particular disjoint regions of the first and/or second facet element or disjoint subsets of facets of the first and/or second facet element. The facets, in particular of the first facet element, are preferably switchable.

In accordance with a further aspect of the invention, the regions illuminated by the at least one auxiliary radiation source, in particular the facets illuminated by the at least one auxiliary radiation source, are distributed, in particular distributed as uniformly as possible, over the second facet element. This allows the energy ratio of the regions illuminated overall by the auxiliary radiation sources, in particular facets, of the second faceted element to the regions illuminated by the at least one main radiation source, in particular facets, of the second faceted element to be altered without a significant alteration of the illumination pupil occurring. The second facets illuminated by the auxiliary radiation source lead in particular to an illumination pupil which has on the reticle, if applicable to the respective illumination setting, a pole balance of less than 3%, a telecentricity of less than 5% of the numerical aperture of the illumination and/or a uniformity error. They lead in particular to an illumination pupil for which the radii of the angular ranges which contain 10%, 50% or 90% of the total energy of the pupil differ by less than 3% of the numerical aperture from a predefined or desired value. Expressed illustratively, the invention provides for both the main radiation source by itself and the auxiliary radiation source by itself to generate the entire illumination setting, wherein the illumination setting generated by the auxiliary radiation source need not be set as exactly as that generated by the main radiation source, since only a small part of the total intensity originates from the auxiliary radiation source. The object is additionally achieved by means of a scanner comprising at least one auxiliary radiation source.

It has been recognized that corresponding auxiliary radiation sources can also be embodied as part of a scanner, that is to say independently of the radiation source module. This makes it possible to increase the flexibility of the scanner, in particular with regard to different useable radiation source modules, in particular with regard to different main radiation sources. The requirements made of the main radiation source, in particular the maximum allowed fluctuations thereof, can be predefined in particular by the operator of the scanner.

A further object of the invention is to improve a projection exposure system. This object is achieved by means of a projection exposure system comprising an illumination system according to the description above. The advantages emerge from those of the illumination system.

In accordance with one aspect of the invention, the projection exposure system comprises a plurality of scanners. The number of scanners of the projection exposure system is in particular at least two, in particular at least three, in particular at least four, in particular at least five, in particular at least six, in particular at least eight, in particular at least ten. It is in particular at most twenty. In accordance with a further aspect of the invention, each of the scanners is assigned at least one auxiliary radiation source. In accordance with a further aspect of the invention, each of the auxiliary radiation sources is assigned in each case to a maximum of one of the scanners. Further objects of the invention are to improve a method for producing a micro- or nanostructured component and a component produced according to the method. The advantages emerge from those described above.

Further advantages and details of the invention will become apparent from the description of exemplary embodiments with reference to the drawings, in which: shows a highly schematic illustration of the parts and subsystems of a projection exposure system, shows a somewhat less highly schematic illustration of an excerpt from a corresponding projection exposure system, and shows a further excerpt from a corresponding projection exposure system.

Firstly, the essential parts of a projection exposure system 1

described below with reference to Figure 1.

The subdivision of the projection exposure system 1 into subsystems that is carried out below serves primarily for the conceptual demarcation thereof. The subsystems can form separate structural subsystems. However, the division into subsystems need not necessarily be reflected in a structural demarcation.

The projection exposure system 1 comprises a radiation source module 2 and a plurality of scanners 3j. The radiation source module 2 comprises a radiation source 4 for generating illumination radiation 5. The radiation source 4 is a free electron laser (FEL), in particular. A synchrotron radiation source or a synchrotron-radiation-based radiation source which generates coherent radiation having very high brilliance can also be involved. By way of example, for such radiation sources, reference should be made to US 2007/0152171 A 1 and DE 103 58 225 B3.

The radiation source 4 has for example an average power in the range of

1 kW to 25 kW. It has a pulse frequency in the range of 10 MHz to

1.3 GHz. Each individual radiation pulse can amount to an energy of 83 μΐ, for example. Given a radiation pulse length of 100 fs, this corresponds to a radiation pulse power of 833 MW.

The radiation source 4 can have a repetition rate in the kilohertz range, for example of 100 kHz, or in the low megahertz range, for example at 3 MHz, in the medium megahertz range, for example at 30 MHz, in the upper megahertz range, for example at 300 MHz, or in the gigahertz range, for example at 1.3 GHz.

The radiation source 4 is an EUV radiation source, in particular. The radiation source 4 emits in particular EUV radiation in the wavelength range of, for example, between 2 nm and 30 nm, in particular between

2 nm and 15 nm.

The radiation source 4 emits the illumination radiation 5 in the form of a raw beam 6. The raw beam 6 has a very small divergence. The divergence of the raw beam 6 can be less than 10 mrad, in particular less than 1 mrad, in particular less than 100 rad, in particular less than 10 rad.

The radiation source module 2 furthermore comprises a beam shaping optical unit 7 disposed downstream of the radiation source 4. The beam shaping optical unit 7 serves for generating a collective output beam 8 from the raw beam 6. The collective output beam 8 has a very small divergence. The divergence of the collective output beam 8 can be less than 10 mrad, in particular less than 1 mrad, in particular less than 100 rad, in particular less than 10 rad.

Moreover, the radiation source module 2 comprises an output coupling optical unit 9 disposed downstream of the beam shaping optical unit 7. The output coupling optical unit 9 serves for generating a plurality of, namely n, individual output beams 10j (i = 1 to n) from the collective output beam 8. The individual output beams 10j in each case form beams for

illuminating an object field 1 lj. The beams can in each case comprise a plurality of separate partial beams 12j. The radiation source module 2 is arranged in an evacuatable housing, in particular.

The scanners 3j in each case comprise a beam guiding optical unit 13j and a projection optical unit 14;.

The beam guiding optical unit 13j serves for guiding the illumination radiation 5, in particular the respective individual output beams 10j, to the object fields 1 lj of the individual scanners 3j. The projection optical unit 14j serves in each case for imaging a reticle 22j arranged in one of the object fields 1 lj into an image field 23_i? in particular onto a wafer 25j arranged in the image field 23j. The beam guiding optical unit 13j comprises, in the order of the beam path of the illumination radiation 5, in each case a deflection optical unit 15j, an input coupling optical unit 16j, in particular in the form of a focusing assembly, and an illumination optical unit 17j. The input coupling optical unit 16i can in particular also be embodied as a Wo Iter type III collector.

The deflection optical unit 15j can also be integrated into the output coupling optical unit 9. The output coupling optical unit 9 can be embodied in particular in such a way that it already deflects the individual output beams 10j in a desired direction.

In accordance with one variant the deflection optical units 15j in their entirety can also be dispensed with.

For different variants of the deflection optical units 15_i? reference should be made to DE 10 2013 223 935.1 , for example, which is hereby incorporated in the present application as part thereof.

The input coupling optical unit 16j serves in particular for coupling in the illumination radiation 5, in particular one of the individual output beams 10i generated by the output coupling optical unit 9, into a respective one of the scanners 3j. The beam guiding optical unit 13j together with the beam shaping optical unit 7 and the output coupling optical unit 9 form parts of an illumination device 18. The illumination device 18, just like the radiation source 4, is part of an illumination system 19.

Each of the illumination optical units 17j is respectively assigned one of the projection optical units 14j. Together the illumination optical unit 17j and the projection optical unit 14j assigned to one another are also referred to as an optical system 20j.

The illumination optical unit 17j serves in each case for transferring illumination radiation 5 to a reticle 22; arranged in the object field 1 lj in an object plane 21. The projection optical unit 14j serves for imaging the reticle 22_i? in particular for imaging structures on the reticle 22_i? onto a wafer 25j arranged in an image field 23j in an image plane 24.

The projection exposure system 1 comprises in particular at least two, in particular at least three, 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, in particular at least nine, in particular at least ten, scanners 3j. The projection exposure system 1 can comprise up to twenty scanners 3j. The scanners 3j are supplied with illumination radiation 5 by the common radiation source module 2, in particular the common radiation source 4. Hereinafter, the common radiation source 4 is also referred to as main radiation source. The projection exposure system 1 serves for producing micro- or nano structured components, in particular electronic semiconductor components. The input coupling optical unit 16j is arranged in the beam path between the radiation source module 2, in particular the output coupling optical unit 9, and a respective one of the illumination optical units 17j. It is embodied in particular as a focusing assembly. It serves for transferring a respective one of the individual output beams 10j into an intermediate focus 26j in an intermediate focal plane 27. The intermediate focus 26j can be arranged in the region of a through opening of a housing of the optical system 20j or of the scanner 3j. The housing is evacuatable, in particular.

By means of the deflection optical unit 15j and/or the input coupling optical unit 16i, the respective individual output beam 10j can be shaped in each case in such a way that it has a predefined divergence and in particular a predefined spatial intensity distribution I*(x, y). To facilitate description, x- and y-coordinates of a Cartesian xyz-coordinate system are used here. The x-coordinate together with the y-coordinate regularly span a beam cross section of the illumination radiation 5. The z-direction regularly runs in the radiation direction of the illumination radiation 5. In the region of the object plane 21 and of the image plane 24, respectively, the y-direction runs parallel to a scan direction. The x-direction runs perpendicular to the scan direction.

The illumination optical unit 17j in each case comprises a first facet mirror 28i and a second facet mirror 29_i? the function of which corresponds in each case to that of the facet mirrors known from the prior art. The first facet mirror 28j can be a field facet mirror, in particular. The second facet mirror 29i can be a pupil facet mirror, in particular. However, the second facet mirror 29j can also be arranged at a distance from a pupil plane of the illumination optical unit 17j. This general case is also referred to as specular reflector.

The facet mirrors 28j, 29j in each case comprise a multiplicity of facets 30, 31. During the operation of the projection exposure system 1, each of the first facets 30 is respectively assigned one of the second facets 31. The facets 30, 31 assigned to one another in each case form an illumination channel of the illumination radiation 5 for illuminating the object field 1 lj at a specific illumination angle.

The channel-by-channel assignment of the second facets 31 to the first facets 30 is carried out depending on a desired illumination, in particular a predefined illumination setting. The facets 30 of the first facet mirror

28i can be embodied such that they are displaceable, in particular tiltable, in particular with two degrees of freedom of tilting in each case. The facets 30 of the first facet mirror 28j are switchable in particular between different positions. In different switching positions they are assigned to different second facets 31 from among the latter. At least one switching position of the first facets 30 can in each case also be provided in which the

illumination radiation 5 impinging on them does not contribute to the illumination of the object field 1 lj. The facets 30 of the first facet mirror 28i can be embodied as virtual facets 30. This should be understood to mean that they are formed by a variable grouping of a plurality of individual mirrors, in particular a plurality of micromirrors. For details, reference should be made to WO 2009/100856 Al, which is hereby incorporated in the present application as part thereof. The facets 31 of the second facet mirror 29j can correspondingly be embodied as virtual facets 31. They can also correspondingly be embodied such that they are displaceable, in particular tiltable. Via the second facet mirror 29j and, if appropriate, via a downstream transfer optical unit (not illustrated in the figures), which comprises three EUV mirrors, for example, the first facets 30 are imaged to the object field 1 lj in the reticle or object plane 21. The individual illumination channels lead to the illumination of the object field 1 lj at specific illumination angles. The totality of the illumination channels thus leads to an illumination angle distribution of the illumination of the object field 1 lj by the illumination optical unit 17j. The illumination angle distribution is also referred to as illumination setting.

In a further embodiment of the illumination optical unit 17j, in particular given a suitable position of the entrance pupil of the projection optical unit 14j, it is also possible to dispense with the mirrors of the transfer optical unit upstream of the object field 1 lj, which leads to a corresponding increase in transmission for the used radiation beam.

The reticle 22; having structures that are reflective to the illumination radiation 5 is arranged in the object plane 21 in the region of the object field 1 1₁. The reticle 22; is carried by a reticle holder. The reticle holder is displaceable in a manner driven by means of a displacement device.

The projection optical unit 14; in each case images the object field 1 lj into the image field 23j in the image plane 24. The wafer 25j is arranged in said image plane 24 during the projection exposure. The wafer 25j has a light- sensitive coating that is exposed during the projection exposure by means of the projection exposure system 1. The wafer 25j is carried by a wafer holder. The wafer holder is displaceable in a manner controlled by means of a displacement device.

The displacement device of the reticle holder and the displacement device of the wafer holder can be signal-connected to one another. They are synchronized, in particular. The reticle 22; and the wafer 25j are

displaceable in particular in a synchronized manner with respect to one another.

One advantageous embodiment of the illumination system 19 is described below. It has been recognized that a free electron laser (FEL) or a synchrotron- based radiation source can advantageously be used as the main radiation source 4. An FEL scales very well, that is to say that it can be operated particularly economically in particular if it is designed to be large enough to supply a plurality of scanners 3j with illumination radiation 5. The FEL can supply in particular up to eight, ten, twelve or even twenty scanners with illumination radiation 5.

It is also possible for more than one main radiation source 4 to be provided. In this case, each of the main radiation sources 4 can respectively be assigned to a specific selection of scanners 3j. The sets of the scanners 3j assigned to different main radiation sources 4 can be disjoint. They can also have non-empty intersections; they can also be identical, in particular. One requirement made of the projection exposure system 1 is that the radiation intensity that reaches the individual reticles and in particular the radiation dose that reaches the wafers 25j can be regulated very exactly and very rapidly. The radiation dose that reaches the wafers 25j is intended to be able to kept as constant as possible, in particular.

Fluctuations of the illumination radiation 5 impinging on the reticle 22_i? in particular of the total intensity of the illumination radiation 5 impinging on the reticles 22_i? and thus of the radiation dose impinging on the wafers 25j, can be attributable to intensity fluctuations of the main radiation source and/or to geometrical fluctuations, in particular to fluctuations of the direction of the raw beam 6 emitted by the main radiation source 4, and/or fluctuations of the cross-sectional profile, in particular in the region of the output coupling optical unit 9, of said raw beam. Fluctuations of the cross- sectional profile can be attributable in particular to divergence fluctuations of the raw beam 6 emitted by the radiation source 4 and/or of the collective output beam 8. Fluctuations of the total intensity of the illumination radiation 5 impinging on the reticle 22; can be caused, in particular, by the fact that alterations of the cross-sectional profile in the region of the output coupling optical unit 9 can lead to a variation of the division ratio of the energy of the collective output beam 8 among the individual output beams 10,

Fluctuations of the illumination radiation 5 impinging on the reticle 22_i? in particular of the total intensity of the illumination radiation 5 impinging on the reticles 22_i? and thus of the radiation dose impinging on the wafers 25j, can also be attributable to fluctuations of the transmission through the scanner 3j. This can also be understood to mean a fluctuation of the transmission between an intermediate focal plane 27 and an object plane 21. This can also be understood to mean a fluctuation of the transmission between the output coupling optical unit 9 and the wafer 25j.

The possibility of dose control according to the invention can be combined with further possibilities of dose control, in particular a specific

embodiment of the beam shaping optical unit 7 and/or of the output coupling optical unit 9.

The invention makes provision for providing at least one auxiliary radiation source 32; for the purpose of dose regulation. The auxiliary radiation source 32; likewise emits illumination radiation 5. It emits in particular illumination radiation 5 having a wavelength corresponding to the wavelength of the illumination radiation 5 emitted by the main radiation source 4. The wavelengths of the illumination radiation 5 emitted by the main radiation source 4 and the illumination radiation 5 emitted by the auxiliary radiation source 32; differ in particular in each case by at most 10%, in particular at most 1%. They are identical, in particular.

The at least one auxiliary radiation source 32; is assigned to a specific of the scanners 3j. It serves to feed a variable, controllable amount of additional illumination radiation 5 to the scanner 3j.

In principle, it is also possible to assign the auxiliary radiation source 32; to a plurality of the scanners 3j. In this case, the illumination radiation from the auxiliary radiation source 32; can be switched for example by means of a displaceable, in particular a pivotable and/or a rotatable, mirror between the scanners 3j. A control device with a sensor, in particular in the form of an energy sensor 33i, is provided for the purpose of controlling the auxiliary radiation source 32j. The energy sensor 33j can be arranged in the beam path of the illumination radiation 5 between the output coupling optical unit 9 and the object plane 21 , in particular in the region between the output coupling optical unit 9 and the intermediate focal plane 27 or in the region between the intermediate focal plane 27 and the object plane 21, in particular in the region of the object plane 21. It can also be arranged in the region between the object plane 21 and the image plane 24, in particular in the region of the projection optical unit 14_i? in particular in the region of the image plane 24. An arrangement in the region of the object plane 21 is preferred.

The energy sensor 33j and the auxiliary radiation source 32; form, in particular, parts of a control loop. The auxiliary radiation source 32; can be driven with the aid of the energy sensor 33; in such a way that, in the event of fluctuations of the main radiation source 4, the radiation power of the illumination radiation 5 that impinges on the reticle 22; can be kept constant. With the aid of the controllable auxiliary radiation source 32_i? it is possible, in particular, for the fluctuation of the radiation power of the illumination radiation 5 that impinges overall on the reticle 22; to be kept smaller than a predefined permissible maximum value, in particular less than 1%, in particular less than 0.3%, in particular less than 0.1%, in particular less than 0.03%, in particular less than 0.01%, of the average radiation power. In absolute values it can be ensured that the fluctuation of the total power of the illumination radiation that impinges on the reticle 22; is less than 10 W, in particular less than 1 W, in particular less than

100 mW, in particular less than 10 mW. The auxiliary radiation source 22; is controllable, in particular, on a time scale of faster than 1 ms.

The auxiliary radiation source 32; emits illumination radiation 5 having a radiation power P_aux in the range of 1 mW to 100 W, in particular in the range of 10 mW to 50 W. The radiation power P_aux of the auxiliary radiation source 32; can be in particular at least 100 mW, in particular at least 500 mW, in particular at least 1 W, in particular at least 3 W, in particular at least 10 W. The radiation power P_aux of the auxiliary radiation source 32; can be in particular at most 50 W, in particular at most 30 W, in particular at most 10 W.

In particular, a xenon source can serve as auxiliary radiation source 32j. This can be expedient, in particular, if the illumination radiation 5 is used in a range around 13.5 nm. Alternatively, the auxiliary radiation source 32; can also be a gadolinium source or a terbium source. This can be expedient, in particular, if the illumination radiation is used in a range around 6.9 nm. Alternatively, a synchrotron-based radiation source, a discharge-induced plasma source (DPP source) or a laser-induced plasma source (LPP source) can also serve as auxiliary radiation source 32j. It is also possible to use one or a plurality of so-called compact sources having a radiation power P_aux of in each case less than 1 W as auxiliary radiation source 32j.

An FEL can also serve as auxiliary radiation source 32j. The auxiliary radiation source 32; can in particular also be embodied identically to the main radiation source 4. The distinction between the main radiation source 4 and the auxiliary radiation source 32; can be, in particular, merely of a conceptual nature. It is possible, in particular, to embody the main radiation source 4 for its part as an auxiliary radiation source with respect to the auxiliary radiation source 32j.

The auxiliary radiation source 32; can be assigned in particular to a plurality of the scanners 30j, in particular to all of the scanners 30j.

It is possible, in particular, to embody the projection exposure system with two radiation sources in the form of FELs. Here both FELs can be assigned in each case to all of the scanners 30j.

The auxiliary radiation source 32; can have a dedicated collector 36.

Advantageously, the illumination radiation 5 from the auxiliary radiation source 32; is distributed as uniformly as possible over location and pupil. This can be achieved, for example, by predefining in a targeted manner which of the first facets 30 and/or in particular which of the second facets 31 are impinged on by illumination radiation 5 from the auxiliary radiation source 32j. Advantageously, the area of the envelopes of the second facets 31 on which illumination radiation 5 can impinge by means of the auxiliary radiation source 32; is at least 30%, in particular at least 50%, in particular at least 70%, in particular 85%, in particular at least 90%, of the area of the envelopes of the second facets 31 on which illumination radiation 5 can impinge. Advantageously, the area of the envelopes of the second facets 31 on which illumination radiation 5 can impinge by means of the main radiation source 4 is at least 50%, in particular at least 75%, in particular 90%, in particular at least 95%, of the area of the envelopes of the second facets 31 on which illumination radiation 5 can impinge. A second facet 31 can be impinged on by illumination radiation 5 of the main radiation source and of an auxiliary radiation source 32_i? respectively, if, in at least one displacement position of at least one first facet 30, the relevant facet is impinged on by illumination radiation 5 of the corresponding source.

The auxiliary radiation source 32; can in each case form part of the radiation source module 2. It can also in each case form part of the illumination device 18. It can also in each case form part of one of the scanners 3j.

The auxiliary radiation source 32; is arranged in particular in the beam path of the illumination radiation 5 downstream of the output coupling optical unit 9.

The illumination radiation 5 from the auxiliary radiation source 32; can be coupled into the optical system 20j in each case by means of a dedicated input coupling optical unit 34;. It can be coupled into the optical system 20j by means of a dedicated intermediate focus 35, which deviates from the intermediate focus 26j of the illumination radiation 5 of the main radiation source 4. In principle, it is also conceivable for the illumination radiation 5 from the auxiliary radiation source 32; to be coupled into the optical system 20i by means of the same input coupling optical unit 16j which is used for coupling the illumination radiation 5 from the main radiation source 4 into said optical system.

Further aspects of the invention are described below with reference to Figure 2.

The invention provides for separate regions, in particular different facets 30, of the first facet mirror 28j to be illuminated with illumination radiation from the main radiation source 4 and with illumination radiation from the auxiliary radiation source 32j. This is indicated by different hatchings in Figure 2. It is expedient here to choose the proportions of the facets 30 illuminated by the different radiation sources 4, 32; in accordance with the different radiation powers P_main of the main radiation source 4 and P_aux of the auxiliary radiation source 32j.

The number of first facets 30 illuminated by the main radiation source 4 and the auxiliary radiation source 32_i? respectively, corresponds precisely to the number of second facets illuminated by said radiation sources 4, 32j. Advantageously, the second facets 31 illuminated by the auxiliary radiation source 32; are distributed uniformly over the pupil or uniformly over the second facet mirror 29j. This allows the variation of the proportion of the power contributed by the auxiliary radiation source 32; in the total power of the illumination radiation 5 used for illuminating the reticle 22_i? without a significant alteration of the illumination pupil occurring.

The region illuminated by the main radiation source 4 on the first facet mirror 28j, in particular the first facets 30 illuminated by the main radiation source 4, and the region illuminated by the auxiliary radiation source 32; on the first facet mirror 28j, in particular the first facets 30 illuminated by the auxiliary radiation source 32_i? can lie directly alongside one another. They can also be arranged at a distance from one another. The regions are embodied in particular in a simply connected fashion.

The surface normal to a first facet 30 is determined by the position of the assigned second facet 31 and by the position of the intermediate focus 26j by which the relevant first facet 30 is illuminated. If adjacent second facets 31 are impinged on by illumination radiation 5 by means of first facets 30 which are illuminated via different intermediate foci 26 , 35 by means of different light sources 4; 32_i? then the surface normals to said first facets 30 can accordingly differ significantly.

The first facets 30 are arranged in particular in such a way that stray light does not contribute to the illumination of the reticle 22j.

The facets 30 are groupable in particular in separate groups, wherein each group of the first facets 30 is assigned to a specific one of the radiation sources 4, 32j. In this case, the facets 30 of the same group are arranged in particular in a simply connected region.

During the production of micro- or nanostmctured components with the projection exposure system 1, firstly the reticles 22; and the wafers 25j are provided. Afterward, a structure on one of the reticles 22; is in each case projected onto a light-sensitive layer of one of the wafers 25 j with the aid of the projection exposure system 1. By means of the development of the light-sensitive layer, a micro- or nanostructure is in each case produced on the wafer 25j and the micro- or nanostmctured component is thus produced. The micro- or nanostmctured component can be in particular a

semiconductor component, for example in the form of a memory chip.

During the projection exposure for producing a micro- or nanostmctured component, both the reticles 22; and the wafers 25j are displaced in a synchronized manner, in particular scanned in a synchronized manner, by corresponding driving of the displacement devices. The wafers 25j are scanned at a scanning rate of 600 mm/s, for example, during the projection exposure. With the system according to the invention comprising a plurality of scanners 3_i? it is possible to expose a plurality of wafers 25j simultaneously in separate scanners 3j.

Claims

Patent Claims:

1. Radiation source module (2) for a projection exposure system (1)

comprising

1.1. at least one main radiation source (4),

1.1.1. which emits illumination radiation (5) having a radiation power P_main , and

1.2. at least one auxiliary radiation source (32j),

1.2.1. which emits illumination radiation (5) having a radiation power P_aux,

1.3. wherein the auxiliary radiation source (32j) serves for

compensating for fluctuations of the main radiation source (4).

2. Radiation source module (2) according to Claim 1, characterized in that a ratio of the radiation power P_main of the main radiation source (4) to the radiation power P_aux of the at least one auxiliary radiation source (32;) is at least 1.5, P_main : P_aux> 1.5.

3. Radiation source module (2) according to either of the preceding

claims, characterized in that a number of the auxiliary radiation sources (32j) is at least 2.

4. Radiation source module (2) according to any of the preceding claims, characterized in that in each case a free electron laser (FEL) or a synchrotron-based radiation source is provided as main radiation source (4) and/or as auxiliary radiation source (32j).

5. Illumination device (18) for a projection exposure system (1) comprising at least one auxiliary radiation source (32j) for

compensating for fluctuations of a main radiation source (4).

6. Illumination device (18) according to Claim 5, characterized by at least two object fields (1 10, ^m which a reticle can in each case be arranged, wherein each of the object fields (1 1 is illuminatable by at least one of the auxiliary radiation sources (320, and each of the auxiliary radiation sources (320 serves for illuminating a maximum of one of the object fields (1 10·

7. Illumination system (19) comprising a radiation source module (2) according to any of Claims 1 to 4.

8. Illumination system (19) comprising an illumination device (18)

according to either of Claims 5 and 6 and a main radiation source (4).

9. Illumination system (19) according to either of Claims 7 and 8,

characterized in that the at least one auxiliary radiation source (320 is parts of a control loop.

10. Illumination system (19) according to any of Claims 7 to 9,

characterized in that the at least one main radiation source (4) and the at least one auxiliary radiation source (320 illuminate different regions of a first facet element (280 and/or of a second facet element (290-

1 1. Illumination system (19) according to any of Claims 7 to 10,

characterized in that regions of a second facet element (290 that are illuminated by the at least one auxiliary radiation source (32j) are arranged in a manner distributed over the second facet element (29j).

12. Scanner (3j) for a projection exposure system (1) comprising at least one auxiliary radiation source (32j) for compensating for fluctuations of a main radiation source (4).

13. Projection exposure system (1) comprising an illumination system (19) according to any of Claims 7 to 1 1.

14. Projection exposure system (1) according to Claim 13, characterized by a number of scanners (3j) of at least two.

15. Projection exposure system (1) according to either of Claims 13 and

14, characterized in that each of the scanners (3j) is assigned at least one auxiliary radiation source (32;), and each auxiliary radiation source (32j) is assigned in each case to a maximum of one of the scanners (3j).

16. Method for producing a microstructured component comprising the following method steps:

providing at least one reticle (22;),

providing at least one wafer (25j) having a coating that is sensitive to the illumination radiation (5),

projecting at least one section of the at least one reticle (22;) onto the at least one wafer (25 j) with the aid of the projection exposure system (1) according to any of Claims 13 to 15,

developing the light-sensitive layer exposed by the illumination radiation (5) on the wafer (25j).

17. Component, produced according to a method according to Claim 16.