WO2009121641A1

WO2009121641A1 - Protection module and euv lithography apparatus with protection module

Info

Publication number: WO2009121641A1
Application number: PCT/EP2009/051127
Authority: WO
Inventors: Dirk Heinrich Ehm
Original assignee: Carl Zeiss Smt Ag
Priority date: 2008-04-03
Filing date: 2009-02-02
Publication date: 2009-10-08
Also published as: DE102008000957A1

Abstract

In EUV lithography apparatuses (10) purged with hydrogen it is suggested that components including hydrogen-sensitive material be arranged within a protection module (24, 29, 32) to increase their useful life. The protection module (24, 29, 32) has a housing with at least one opening, in which at least one component is arranged, wherein one or more gas inlets (23, 30, 33) are provided to introduce a gas flow into the housing, which exits through the at least one opening.

Description

Protection Module and EUV Lithography Apparatus with Protection Module

Field of the Invention

The present invention relates to a protection module, in particular for an EUV lithography apparatus comprising a housing with at least one opening, in which at least one component is arranged. Further, the present invention relates to an EUV lithography apparatus, a projection system and an illumination system for EUV lithography apparatuses, wherein at least one such protection module is arranged.

Background and Prior Art

In EUV lithography apparatuses, reflective optical elements for the extreme ultraviolet (EUV), or soft X-ray wavelength ranges (e.g. wavelengths between about 5 nm and 20 nm), such as photomasks or multilayer mirrors are used for lithography of semiconductor components. Since EUV lithography apparatuses usually have a plurality of reflective optical elements, these must have a reflectivity which is as high as possible, to ensure sufficiently high overall reflectivity. The reflectivity and useful life of the reflective optical elements can be impaired by contamination of the optically used reflective surface of the reflective optical elements as a result of the short-wave irradiation together with residual gases in the processing atmosphere. Since usually a plurality of reflective optical elements are arranged in series in an EUV lithography apparatus, even slight contamination of each individual reflective optical element has a substantial effect on the overall reflectivity.

A possibility to protect an EUV lithography apparatus, or its optical elements, from contamination, is to purge the interior of the EUV lithography apparatus with molecular hydrogen. Herein, the entire interior of the EUV lithography apparatus can be purged. However, EUV lithography apparatuses are often subdivided in various vacuum chambers, which can be each individually purged with hydrogen as needed, such as the exposure system or the projection system. Individual or a plurality of reflective optical elements can also be encapsulated, however, to create a micro-environment within the encapsulation. In such cases it is sufficient to purge only the interior of the encapsulation with hydrogen. Molecular hydrogen has the advantage of very high transmission in the range of the EUV, or soft X-ray wavelengths. It prevents hydrocarbons, in particular, from reaching the surfaces of the optical elements and being deposited there as carbon-containing contamination. For cleaning purposes, atomic hydrogen is often introduced into the interior of a vacuum environment, in particular to remove carbon-containing contamination. Atomic hydrogen, which can be produced on filaments, for example, or by interaction with EUV radiation, reacts with the deposited carbon-containing contamination to form volatile hydrocarbons, which can be pumped off.

A drawback of cleaning with atomic hydrogen or purging with molecular hydrogen during irradiation with EUV light is that the hydrogen, in particular atomic hydrogen, very strongly interacts with other materials present as contamination. It forms, for example, hydride compounds with metals. This results in the useful life of components, which comprise such materials, being shortened. This is a problem, in particular, when these materials, which have a higher reaction rate with hydrogen, cannot be replaced by more inert materials. This is the case, amongst others, for sensors used for aligning the optical elements or for monitoring the radiation intensity, or the degree of contamination.

While components with hydrogen-sensitive materials may be encased in protective housings, in many cases it cannot be avoided that an opening remains to ensure the operability of the component in question.

Summary of the Invention

It is an object of the present invention to provide a protection module, in particular for an EUV lithography apparatus, or an EUV lithography apparatus, wherein the useful life of components with hydrogen-sensitive materials is increased over and above conventional EUV lithography apparatuses.

This object is achieved by a protection module having a housing with at least one opening, in which at least one component is arranged, wherein one or more gas inlets are provided to introduce a gas flow into the housing, which exits through said at least one opening. Further, this object is achieved by a protection module having a housing with at least one opening, in which at least one component is arranged, wherein at least one gas inlet and at least one gas outlet is provided, which are arranged in such a way that a gas flow is created flowing between the sensor and said at least one opening.

Preferably, the protection modules are used in EUV lithography apparatuses, in particular when substances are present in the residual gas atmosphere, which could damage components. These can be, for example, atomic hydrogen for cleaning contamination or other reactive substances. A further preferred field of use is measuring arrangements, in which the conditions within an EUV lithography apparatus are simulated in test arrangements.

It has been found that a component arranged within a housing, said component comprising material which is particularly sensitive to one or more given substances, can be effectively protected from coming into contact with the substance in question, by ensuring that a gas flow is created in the interior of the housing. The substance can be prevented from coming into contact with the component by having it exit through the at least one opening and form a counter current against any inflowing deleterious gas molecules or atoms, thus reducing the likelihood of molecules or atoms of the substance in question being introduced into the housing at all. The gas flow can also be arranged in such a way that it flows between the components and the at least one opening, thus forming a kind of protective shield to prevent the deleterious substance from reaching the component, wherein the gas flow exits through the at least one gas outlet.

The at least one opening can be, for example, one or more openings, which have to be provided in the housing, so that the component can be used according to its function. It can also be a leak in the housing, however. In particular in the case of hydrogen the smallest openings are sufficient to enable individual molecules or atoms to penetrate into the housing, since hydrogen has a very small radius.

The object is also achieved by an EUV lithography apparatus, or a projection system or an illumination system for an EUV lithography apparatus, in which at least one of these protection modules is arranged.

Advantageous embodiments are found in the dependent claims.

Brief Description of the Drawings

The present invention will be explained with reference to a preferred embodiment in more detail. In the drawings:

Fig. 1 schematically shows an embodiment of an EUV lithography apparatus; Fig. 2a schematically shows a first embodiment of a protection module with a gas inlet;

Fig. 2b schematically shows a second embodiment of a protection module with a gas inlet and a gas outlet;

Figs. 3a, b schematically show a third embodiment of a protection module with an optimized gas inlet in two variants;

Fig. 4 schematically shows a fourth embodiment of a protection module with a gas inlet;

Fig. 5 schematically shows a fifth embodiment of a protection module with a gas inlet and a gas outlet;

Fig. 6 schematically shows a sixth embodiment of a protection module with a gas inlet and an opening;

Fig. 7 schematically shows a seventh embodiment of a protection module with a gas inlet and two openings;

Fig. 8 schematically shows an eighth embodiment of a protection module with two gas inlets; and

Fig. 9 schematically shows a ninth embodiment of a protection module with a gas inlet and two openings.

Detailed Description of the Invention

Fig. 1 schematically shows an EUV lithography apparatus 10. Important components are a beam-shaping system 11 , an illumination system 14, a photomask 17 and a projection system 20. The EUV lithography apparatus 10 is operated under vacuum conditions so that EUV radiation is absorbed as little as possible in the interior.

A beam source 12 can be, for example, a plasma source or a synchrotron. The emerging radiation in the wavelength range of about 5 nm to 20 nm is at first collimated in collimator 13b. Moreover, the desired operating wavelength is filtered out with the aid of a monochromator 13a by varying the incident angle. In the above mentioned wavelength range, collimator 13b and monochromator 13a are usually configured as reflective optical elements. Collimators are often dish-shaped reflective optical elements to achieve a focusing or collimating effect. The reflection of the radiation is on the concave surface, wherein often no multilayer system is used for reflection on the concave surface, since a wavelength range is to be reflected, which is as broad as possible. Filtering out a narrow wavelength band by reflection is then carried out on the monochromator, often with the aid of a lattice structure or a multilayer system.

The operating beam processed with respect to its wavelength and spatial distribution in the beam-shaping system 11 is then introduced into illumination system 14. In the example shown in Fig. 1 , illumination system 14 has two mirrors 15, 16, configured as multilayer mirrors in the present example. Mirrors 15, 16 direct the beam onto photomask 17 having the structure to be formed on wafer 21. Photomask 17 is also a reflective optical element for the EUV and soft X-ray range, which is exchanged depending on the manufacturing process. With the aid of projection system 20, the beam reflected by photomask 17 is projected onto wafer 21 thereby imaging the structure of the photomask onto it. Projection system 20 has two mirrors 18, 19 in the example shown, which in the present example are also configured as multilayer mirrors. It should be noted that both projection system 20 and illumination system 14 can each also have only one, or three, four, five and more mirrors.

Beam-shaping system 11 as well as illumination system 14 as well as projection system 20 are configured as vacuum chambers, since multilayer mirrors 15, 16, 18, 19, in particular, can only be operated in a vacuum. Otherwise too much contamination would be deposited on their reflective surfaces, which would lead to substantial deterioration in reflectivity.

In the example shown in Fig. 1 of an EUV lithography apparatus 10, beam-shaping system 11 and projection system 20 configured as separate vacuum chambers, are purged with molecular hydrogen via hydrogen inlets 22, 31. This is to prevent contaminating substances such as hydrocarbons from reaching collimator 13b or monochromator 13a, or EUV mirrors 18, 19, and from depositing there as contamination on the optically used surfaces. Purging can also be carried out during the operation of EUV lithography apparatus 10. Herein, the EUV radiation leads to a portion of molecular hydrogen being split into atomic hydrogen, which, in turn, can react with already present contamination to form volatile compounds. In the example shown, an additional pump 25 is provided for pumping off these volatile compounds in beam-shaping system 11. In projection system 20, the pumping system already present for maintaining the vacuum within projection system 20 is used (not shown). In illumination system 14, hydrogen purging is also used to avoid contamination. However, not the entire vacuum chamber of illumination system 14 is purged. Rather, mirrors 15, 16 are enclosed in an encapsulation 26, which separates mirrors 15, 16 from the remaining vacuum within illumination system 14. A micro-environment is thus created around mirrors 15, 16. On the one hand, encapsulation 26 serves to additionally protect against contamination of mirrors 15, 16 by outgassing components within illumination system 14. On the other hand, limiting hydrogen purging to the interior of encapsulation 26 has the effect that components, comprising materials, which could be attacked by hydrogen, can be used at less risk within illumination system 14, but outside of encapsulation 26.

To remove any contamination nevertheless arising on mirrors 15, 16, a filament 28 is additionally provided within encapsulation 26, which should be of a metal or a metal alloy with a very high melting point, such as tungsten. The hydrogen introduced via inlet 27 is fed to heated filament 28 for cleaning purposes, so that molecular hydrogen is split into atomic hydrogen. The reaction rate, or splitting rate, is higher than with the sole interaction of the operating radiation of EUV lithography apparatus 10 with the molecular hydrogen of the hydrogen purging. Due to this increased concentration in atomic hydrogen, any contamination present is removed at an increased rate and transformed into volatile compounds. These volatile compounds are removed from the encapsulation with a pump not shown.

Unfortunately, the materials cannot be replaced in all necessary components in such a way that they are really inert to hydrogen. This applies, in particular, to components having functionalities depending on the actual choice of material, such as with magnets. To protect these components, they can also be encased in a housing. It can happen, however, that the housings cannot be made absolutely leak-proof, or that even large openings have to be provided, so that the component, such as a sensor, can fulfill its function. It is well known that certain materials, such as magnetic materials, on the basis of neodymium-iron-boron alloys or samarium-cobalt alloys, titanium alloys, hardened steel alloys, amongst others, are attacked by both atomic and molecular hydrogen, so that they become brittle, and the useful life of the component is shortened correspondingly. Said materials may e.g. be utilized for mechanical or electromechanical components such as components used for moving other components amongst others. Housings can also have leaks on weld seams, through which undesirable substances, such as hydrogen, can penetrate. The sensors can be sensors, for example, used for the detection of the mirror position and their adjustment, or sensors for measuring the intensity of the operating radiation or the degree of contamination within the EUV lithography apparatus. These sensor types, which often work on an optical basis, can only be used if they can be directly exposed to the EUV radiation or other radiation within each vacuum chamber. This is why they cannot be encased in an absolutely leak-proof manner without degrading their operability.

In the example shown in Fig. 1 , such hydrogen-sensitive components are encased in protection modules 24, 29, 32. Each protection module 24, 29, 32 has its own gas inlet 23, 30, 33. These gas inlets 23, 30, 33 are used to feed other gases than the gas provided for purging the EUV lithography apparatus, hydrogen in the present example, to protection modules 24, 29, 32. Inert gases, such as molecular nitrogen, are particularly advantageous. Preferably, inert gases, such as argon or krypton, or helium, neon or xenon, are used. The gases fed in via gas inlets 23, 30 33 are used to purge the interiors of protection modules 24, 29, 32. This is how a gas flow is created, which escapes from the protection module through the one or more openings of the protection module, such as is the case with protection module 24 and protection module 29. In the case of protection module 32, an additional gas outlet 34 is provided, to which a pump 35 is connected. The gas flow thus created within protection module 32 primarily exits protection module 32 via gas outlet 34.

All protection modules 24, 29, 32 have in common that the gas flow within each protection module 24, 29, 32 counteracts penetration in particular of hydrogen molecules or hydrogen atoms. It has been shown to be advantageous if the pressure conditions within the protection modules and within the vacuum chambers surrounding them is adjusted in such a way that the pressure within the protection modules is higher than within the vacuum chambers surrounding them, such as encapsulation 26 or beam-shaping system 1 1 , or projection system 20. This pressure gradient additionally prevents introduction of hydrogen atoms or molecules, or other contaminating substances.

Various embodiments of protection modules for use in EUV lithography apparatuses or in measuring arrangements, in which the conditions within EUV lithography apparatuses are simulated for testing purposes, or wherein preparatory measurements are carried out on components before they are used in EUV lithography apparatuses, will be explained in the following. The protection module schematically shown in Fig. 2a has a housing 40a, in which a component to be protected is enclosed. Housing 40a has a weld seam, however, which has developed a leak over time, symbolized by an elongate narrow opening 42a. In reality, instead of one large opening 42a, there will rather be a large number of small openings in the material, which has meanwhile become porous. In particular gases with a very small radius, such as hydrogen, can penetrate into the interior of housing 40a through the smallest leak and attack materials of the component to be protected there or deposit in undesirable places. To avoid this, a gas inlet 41a is provided on the protection module shown in Fig. 2a. A different, harmless gas is fed into housing 40a via this gas inlet 41a. The gas introduced into housing 40a through said gas inlet 41 a can escape again through opening 42a, so that a gas flow is created within housing 40a. This gas flow ensures that contaminating or reactive substances, which can penetrate through opening 42a into the housing, are much less likely to enter opening 42a in the direction of the housing interior. To increase this effect, it has been shown to be advantageous to configure gas inlet 41a in such a way that the molecules or atoms exiting there have a velocity, which is as high as possible. This can be achieved, for example, by making the diameter of gas inlet 41 a very small compared to the diameter of housing 40a, or by making the volume of gas inlet 41 a in the area in front of the opening into housing 40a small compared to the volume of housing 40a, preferably small compared to the free volume within housing 40a. This results in the atoms or molecules exiting from gas outlet 41 a being strongly accelerated.

In Fig. 2b a further variant of a protection module is shown. Important components are, again, a housing 40b and a gas inlet 41 b. The housing has a larger opening 42b in the present case, which is necessary for a sensor enclosed in housing 40b to be operated according to its function. Additionally, the protection module shown in Fig. 2b has a gas outlet 43b. Between gas inlet 41 b and gas outlet 43b, a gas flow is created within housing 40b, which creates a kind of protective curtain between opening 42b and the sensor arranged within housing 40b. This protective curtain of gas prevents deleterious atoms or molecules, which might have penetrated into housing 40b through opening 42b, from reaching the sensor and damaging it. Moreover, a portion of the gas fed into housing 40b via gas inlet 41 b will also exit through opening 42b. The steeper the pressure gradient from within housing 40b to outside of housing 40b, the greater the proportion of the gas flow which exits through opening 42b and therefore prevents penetration of other molecules or atoms into housing 40b. Preferably, the gas outlets are connected to a pump or a vacuum system, in which there is a lower pressure than in the protection module, so that an intentional gas flow can be created. Preferably, the pressure is lower than outside of the opening or openings, through which deleterious molecules or atoms can penetrate the housing of the protection module.

A further example of a protection module is schematically shown with a variant in Figs. 3a, b. A sensor 44c is arranged within housing 40c. An elongate opening 42c is provided in housing 40c for the correct operability of sensor 44c. Fluid-dynamic calculations were used to optimize on the one hand the form of opening 42c and its arrangement in the housing, and on the other hand also the form and the arrangement of gas inlet 41c, or 41c', to achieve the best possible suppression of penetration of undesirable molecules or atoms, such as of hydrogen, into the interior of housing 40c through opening 42c. In the present example, not only opening 42 has the form of a slit, but also gas inlet 41c opens out in the form of a slit in its opening area. Gas inlet 41c in Fig. 3a and gas inlet 41c' in Fig. 3b are different from one another in that gas inlet 41c opens out into housing 40c in the form of a large slit-shaped opening. Gas inlet 41c' of Fig. 3b, on the other hand, is formed in the opening area in such a way that a plurality of small openings 46 are formed, through which the gas fed in through gas inlet 41c penetrates into housing chamber 40c. This has the effect that the gas molecules, or gas atoms, are strongly accelerated when they enter into housing 40c, so that a gas flow is created with increased atomic or molecular velocities, which also exits from opening 42c with an increased velocity. This further reduces the probability that undesirable substances can enter into housing 40c.

A further special feature of the protection modules shown in Figs. 3a, b, is that they are coated on the front side of housing 40c around opening 42c with a material having a high reaction rate with atomic and/or molecular hydrogen. This can be various metals, such as titanium, tantalum, niobium, zirconium, thorium, barium, magnesium, aluminum, ruthenium, platinum, palladium, yttrium or cerium. If hydrogen atoms or molecules come near housing 40c, they are intercepted, so to speak, by the reactive coating, since they react with the material of the coating with high probability and therefore enter through opening 42c into housing 40c with only low probability. Depending on which gas is used to purge the exterior of housing 40c or which particularly deleterious substances are in the surrounding space, which should not penetrate the interior of housing 40c, a different reactive coating around opening 42c can also be chosen. An important criterion for material selection of the coating is that it has a high reaction rate with the undesirable substance. In the example shown in Fig. 4 of a protection module, a sensor 44d is arranged in a housing 4Od, which has an opening 42d for sensor 44d. To create a gas flow flowing past sensor 44d to prevent contamination of the sensor, or damage to the sensor, by penetrating substances, a gas inlet 41 d is provided. The gas flow created is indicated by means of arrows.

A further example of a protection module is schematically shown in Fig. 5. In comparison with the example of Fig. 4, a gas outlet 43e is additionally provided, which is arranged opposite gas inlet 41 e. Gas inlet 41 e and gas outlet 43e are arranged in such a way on housing 4Oe relative to sensor 44e and opening 42e that a gas flow as indicated by the arrows is created, which flows between opening 42e and sensor 44e past sensor 44e. This is how the gas flow forms a kind of protective curtain, which prevents undesirable substances from reaching sensor 44e.

In the example schematically shown in Fig. 6 a component 45f is encased in housing 4Of. To keep the interior of housing 4Of free of undesirable substances, in particular of hydrogen, a gas inlet 41f and an opening 42f are provided. The arrangement and shape of opening 42f was determined based on fluid-dynamic optimizing calculations. Parameters used therein were the suppression rate for the undesirable substance, the arrangement of gas inlet 41f and the free volume within housing 4Of surrounding component 45f. The gas flow created in housing 4Of completely flows around component 45f. In order to additionally increase the velocity of the molecules or atoms in the gas flow and to further reduce the penetration probability of the undesirable substance through opening 42f, an external gas outlet 43f is provided for sucking off the gas flow through opening 42f.

The example schematically shown in Fig. 7 coincides in essential components with the protection module of Fig. 6. However, the parameters for the calculation of the fluid- dynamically optimized opening 42g, 42g' were changed. By using a different inert gas for purging the interior of housing 4Og to that in the example shown in Fig. 6, it has been found that providing two openings 42g, 42g', albeit having a small cross-sectional area, is advantageous to efficiently suppress penetration of undesirable substances, in particular hydrogen.

Depending on the geometry of the housing and the enclosed component or components, the purging gas used and the desired suppression rate for substances present outside of the protection module, such as hydrogen, three, four, five or more openings and/or two, three, four, five or more gas inlets can also be advantageous. Preferably, the openings are dimensioned such that a counter current is created against the penetrating deleterious substances, such as hydride-forming hydrogen molecules or atoms or other components of the surrounding residual gas atmosphere.

Fig. 8 shows an exemplary embodiment of a protection module in a schematic way, wherein for protecting sensor 44h within housing 4Oh, two gas inlets 41 h and 41 h' are provided. On the basis of fluid-dynamic optimizing calculations they are arranged in opposition. The gas flows exiting from each gas inlet 41 h, 41 h' unite and exit housing 4Oh as a combined gas flow through opening 42h. This ensures sufficient protection against the introduction of undesirable substances into housing 4Oh.

Fig. 9 schematically shows a protection module used for housing a component 45i including material sensitive to hydrogen. A gas inlet 41 i is provided on housing 4Oi, which ensures that a slight overpressure is present within housing 4Oi compared with the outside of housing 4Oi. If during the lifetime of housing 4Oi, leaks 42i, 42i' develop, such as due to the interaction of the housing material with atomic or molecular hydrogen, the gas introduced via gas inlet 41 i, such as argon or krypton, exits housing 4Oi via openings 42i, 42i'. Due to the pressure gradient, a gas flow is created indicated by the arrows, which suppresses introduction of, for example, molecular or atomic hydrogen through openings 42i, 42i'. By these means, the useful life of component 45i is considerably increased. If the introduction of hydrogen is to be prevented, helium is preferably used for purging, which has a smaller radius than the other inert gases, so that a gas flow is created even if the leaks are very small.

List of Reference Numerals

10 EUV lithography apparatus

11 beam-shaping system

12 EUV radiation source

13a monochromator

13b collimator

14 illumination system

15 first mirror

16 second mirror

17 mask

18 third mirror

19 fourth mirror

20 projection system

21 wafer

22 hydrogen inlet

23 inert gas inlet

24 protection module

25 pump

26 encapsulation

27 hydrogen inlet

28 filament

29 protection module

30 inert gas inlet

31 hydrogen inlet

32 protection module

33 inert gas inlet

34 gas outlet

35 pump

40a, ,b, c, ,d,e,f,g,h,i housing

41a, ,b, c, c',d,e,f,g,h,h',i gas inlet

42a, ,b, c, d,e,f,f,g,g',h,i,ϊ opening

43b, ,e, f.g gas outlet

44c,d, e, h sensor

45f,g,i component

46 opening

Claims

1. A protection module, comprising a housing (40a-i) with at least one opening (42a-i), in which at least one component (44c,d,e,h, 45f,g,i) that does not serve to process or direct a radiation beam is arranged, and wherein one or more gas inlets (41a-i) are provided, to introduce a gas flow into housing (40a-i) exiting through said at least one opening (42a-i).

2. The protection module according to claim 1 , wherein said at least one gas inlet (41 a-i) and said at least one opening (42a-i) are arranged with respect to each other in such a way that the gas flow flows past the component (44c,d,e,h, 45f,g,i).

3. A protection module, comprising a housing (40a-i) with at least one opening (42a-i), in which at least one component (44c,d,e,h, 45f,g,i) that does not serve to process or direct a radiation beam is arranged, wherein at least one gas inlet (41 a-i) and at least one gas outlet (43b,e,f,g) are provided, which are arranged in such a way that a gas flow is created, which extends between the component (44c,d,e,h, 45f,g,i) and said at least one opening (42a-i).

4. The protection module according to any one of claims 1 to 3, wherein said at least one opening (42a-i) has the form of a slit.

5. The protection module according to any one of claims 1 to 4, wherein said at least one gas inlet (41 a-i) is configured in such a way that a gas flow is created with high molecular or atomic velocities.

6. The protection module according to any one of claims 1 to 5, wherein the housing (40a-i) is coated on its outside, at least in the area of said at least one opening (42a-i), with a material having a high reaction rate with atomic and/or molecular hydrogen.

7. The protection module according to any one of claims 1 to 6, wherein the shape of said at least one opening (42a-i) is optimized in such a way that the penetration of atoms or molecules, in particular of hydrogen, is suppressed.

8. The protection module according to any one of claims 1 to 7, wherein the arrangement of said at least one gas inlet (41 a-i) is optimized in such a way that the penetration of atoms or molecules, in particular of hydrogen, is suppressed.

9. The protection module according to any one of claims 1 to 8, wherein outside of the housing (40a-i), a gas outlet (43f-g) is arranged to suck off the gas flow exiting through said at least one opening (42a-i).

10. The protection module according to any one of claims 1 to 9, wherein a sensor (44c,d,e,h) is arranged in the housing (40a-i).

11. The protection module according to any one of claims 1 to 10, wherein at least one gas inlet (41 a-i) is provided as an inert gas inlet.

12. An EUV lithography apparatus, in which at least one protection module (24, 29, 32) according to any one of claims 1 to 1 1 is arranged.

13. The EUV lithography apparatus according to claim 12, comprising a hydrogen purge (22, 27, 31 ), while a different gas is fed to the at least one protection module (24, 29, 32).

14. The EUV lithography apparatus according to claim 12 or 13, wherein a higher pressure is present within the at least one protection module (24, 29, 32) than outside of it.

15. A projection system for an EUV lithography apparatus, in which at least one protection module (32) according to claims 1 to 11 is arranged.

16. The projection system according to claim 15, comprising a hydrogen purge (31 ), while a different gas is fed to the at least one protection module (32).

17. The projection system according to claim 15 or 16, wherein a higher pressure is present within the at least one protection module (32) than outside of it.

18. An illumination system for an EUV lithography apparatus, in which at least one protection module (29) according to any one of claims 1 to 11 is arranged.

19. The illumination system according to claim 18, comprising a hydrogen purge (27), while a different gas is fed to the at least one protection module (29).

20. The illumination system according to claim 18 or 19, wherein a higher pressure is present within the at least one protection module (29) than outside of it.