Measuring apparatus and method for inspecting photomasks for EUV microlithography

Abstract

To provide a measurement apparatus and method for mask inspection, in which the risk of contaminations is reduced.SOLUTION: A measurement apparatus for inspection of photomasks, comprises an EUV radiation source (14), an illumination system (16), a projection lens (22), and an EUV image sensor (24). EUV radiation emitted by the EUV radiation source (14) is guided via the illumination system (16) to a photomask (17). EUV radiation reflected at the photomask (17) is guided via the projection lens (22) to the EUV image sensor (24) such that the photomask (17) is imaged on the EUV image sensor (24). A pellicle (30) is arranged between the EUV radiation source (14) and the illumination system (16), with the result that the EUV radiation passes through the pellicle (30) between the EUV radiation source (14) and the illumination system (16). The invention also relates to a method for inspecting photomasks.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a measuring device and method for inspecting a photomask for EUV microlithography.

Background Art

[0002] In particular, in a microlithography projection exposure apparatus used for manufacturing an integrated circuit having a particularly minute structure, a photomask is used. In order to transfer the mask structure onto a lithography object, a photomask irradiated with extreme ultraviolet radiation (EUV) is imaged onto the lithography object.

[0003] In order to ensure a high quality of the image formed on the lithography object, the photomask needs to be of the correct size and not be adversely affected by contaminants. It is a known practice to subject the photomask to inspection before or during the operation of a microlithography projection exposure apparatus. For this purpose, a so-called aerial image of the photomask or a part of the photomask is generated, and in the process, the photomask is imaged onto an EUV image sensor instead of onto the lithography object. Based on the imaging onto the EUV image sensor, it is possible to evaluate whether there are defects and contaminants on the photomask.

[0004] This mask inspection needs to be performed so that the measurement results are not modified by contamination. Specifically, the photomask needs to be prevented from being contaminated as a result of the mask inspection procedure.

Summary of the Invention

[0005] The present invention provides a measuring device and method for mask inspection, based on the aim of reducing the risk of contamination. This aim is achieved by the features of the independent claims. Advantageous embodiments are specified in the dependent claims.

[0006] The measuring apparatus according to the present invention for inspecting a photomask includes an EUV radiation source, an illumination system, a projection lens, and an EUV image sensor. EUV radiation emitted from the EUV radiation source is guided to the photomask via the illumination system. EUV radiation reflected from the photomask is guided to the EUV image sensor via the projection lens so that the photomask is imaged onto the EUV image sensor. A pellicle is positioned between the EUV radiation source and the illumination system so that the EUV radiation passes through the pellicle between the EUV radiation source and the illumination system.

[0007] The use of measuring devices for inspecting EUV photomasks is known to carry a significant risk of contamination of the photomasks as a result of the inspection procedure. One source of contamination is the EUV radiation source itself, as particles are generated during the operation of the EUV radiation source. If these particles diffuse freely within the measuring device, they will adhere to the photomask. This is particularly harmful because the entire patch of semiconductor component exposed with the contaminated photomask may become unusable.

[0008] This invention proposes a pellicle placed between an EUV radiation source and an irradiation system. The pellicle prevents particles from diffusing from the EUV radiation source into the irradiation system. This reduces the risk of contamination within the measuring device, and in particular, the risk of contamination of the photomask.

[0009] A pellicle refers to a film designed to allow EUV radiation to pass through but to block the passage of particles. Because materials generally have high absorbency with respect to EUV radiation, the material and structure of the pellicle must be carefully adapted when considering its use in measuring devices for mask inspection. For example, unlike with visible light, it is not feasible to use a glass plate as protection against contamination. The EUV radiation would be absorbed by the glass plate and would not reach the image sensor with sufficient intensity.

[0010] In one embodiment, the pellicle is a CNT (carbon nanotube) pellicle, i.e., a film made of carbon nanotubes. The density and bundle structure of the carbon nanotubes can be selected so that, firstly, the film transmits EUV radiation, and secondly, particles are trapped by the film and cannot pass through it. To give the film sufficient resistance to radical ions and molecules, the film may be coated. In alternative embodiments, the pellicle includes a film made of silicon, silicon nitride, or any other silicon-containing material. When sufficiently thin, a film made of such a silicon material also exhibits sufficient transmission of EUV radiation.

[0011] The pellicle can be positioned so that EUV radiation from an EUV radiation source passes through the pellicle before entering the illumination system. The illumination system may include one or more EUV mirrors that reflect the EUV radiation along the path between the EUV radiation source and the photomask. The pellicle can be positioned between the EUV radiation source and the first EUV mirror of the illumination system so that the EUV radiation is not reflected before it by another EUV mirror of the illumination system. The illumination system can be configured to illuminate a specific portion of the photomask. The illumination system can be configured so that the intensity of the EUV radiation is substantially uniform within the illuminated portion.

[0012] The optical region of an EUV mirror can be formed by a highly reflective coating. The coating can be a multilayer coating, particularly one having alternating layers of molybdenum and silicon. Using such a coating, it is possible to reflect approximately 70% of the incident EUV radiation. The term EUV radiation is used to refer to electromagnetic radiation in the extreme ultraviolet spectral region with wavelengths between 5 nm and 100 nm, particularly between 5 nm and 30 nm.

[0013] The projection lens of the measuring device may include multiple EUV mirrors that reflect EUV radiation between the photomask and the image sensor. The projection lens may include a first mirror M1 that captures the EUV radiation reflected by the photomask. The EUV radiation reflected by the first mirror M1 can be guided to the EUV image sensor via one or more further mirrors of the projection lens. Specifically, the EUV radiation can be guided to the image sensor such that an image of the photomask, specifically a portion of the photomask, is formed on the image sensor. The portion of the photomask that is imaged on the image sensor may correspond to a small portion of the photomask.

[0014] The measuring device may include a vacuum chamber where a vacuum exists during measurement. A projection lens, irradiation system, and / or EUV radiation source can be placed within the vacuum chamber. A sub-chamber can be formed within the vacuum chamber, separated from the rest of the vacuum chamber by an intermediate housing. The EUV radiation source can be placed within the sub-chamber.

[0015] The intermediate housing may include a pressure equalization channel, which thereby equalizes the pressure between the sub-chamber and the rest of the vacuum chamber. However, perfect pressure equalization is not always possible between the sub-chamber and the rest of the vacuum chamber. For example, a purge gas can be introduced into the sub-chamber to remove contamination caused by an EUV radiation source. This can cause the total pressure or partial pressure and / or gas composition within the sub-chamber to differ from that of the rest of the vacuum chamber.

[0016] The sub-chamber may have an exit opening through which EUV radiation emitted by an EUV radiation source passes in the direction of the irradiation system. The exit opening may be covered by a pellicle, so that all EUV radiation exiting the sub-chamber through the exit opening travels through the pellicle, i.e., passes through the pellicle. The pellicle may be flush with the outer circumference of the housing surrounding the opening, so that particle movement between the sub-chamber and the rest of the vacuum chamber at the transition between the pellicle and the housing or between the pellicle frame and the housing is prevented. The pellicle may be designed to withstand any pressure differences that may exist above the pellicle during the operation of the measuring device.

[0017] The pellicle can be mounted to the frame. The pellicle can be fixed to the frame such that the opening through which the frame is spanned is covered by the pellicle. Connection to the partial housing of the vacuum chamber can be made via the frame. The connection between the frame and the supporting structure of the measuring device, specifically the connection between the frame and the partial housing of the vacuum chamber, can be a releasable connection to allow for pellicle replacement. The pellicle may need to be replaced if it becomes contaminated after a certain period of use. The pellicle can be a consumable item designed to be replaced periodically within the scope of maintenance standards. Pellicle replacement can be done manually. A motor-driven mechanism for pellicle replacement is also possible.

[0018] The measuring device may include a holding device that supports multiple pellicles. Each pellicle may be suspended on a frame. The holding device may have or include multiple identical frame component sections having multiple pellicles. The measuring device may be configured so that in a first state of the holding device, EUV radiation passes through a first pellicle, and in a second state of the holding device, EUV radiation passes through a second pellicle. The holding device may have more than two pellicles and more than two associated states. The holding device may include, for example, a turret unit where the exchange between pellicles is brought about by rotational motion. The measuring device may include an electrically driven unit for switching the states of the holding device. The measuring device may include a control unit for controlling the holding device.

[0019] By providing multiple pellicles that can be positioned in front of the EUV radiation source, the complexity of maintenance can be reduced. In a measurement device with a single pellicle in front of the EUV radiation source, the maintenance interval depends on how long it takes for the individual pellicle to wear out. With multiple pellicles, the maintenance interval is extended proportionally to the number of pellicles. After a pellicle wears out, the retention device is simply activated to insert the next pellicle into the EUV beam path.

[0020] The measuring device may include a loading mechanism intended for removing the pellicle from the vacuum chamber of the measuring device and replacing it with a new pellicle. The pellicle may be replaced together with the frame. The loading mechanism may be designed to replace multiple pellicles in a single replacement operation. The replacement operation can be performed as an automated process without manual intervention.

[0021] To replace the pellicle, the vacuum inside the vacuum chamber can be released so that atmospheric pressure is present inside the vacuum chamber. Next, to remove and replace the pellicle, an opening in the vacuum chamber housing can be opened, allowing access to the vacuum chamber through it.

[0022] The measuring device may also include an airlock through which the pellicle is replaced. In the first state of the airlock, the same pressure can exist in both the airlock chamber and the vacuum chamber, and as a result, the photomask can be transported without a pressure difference between the airlock chamber and the vacuum chamber. In the second state of the airlock, a pressure higher than the vacuum pressure and corresponding to the pressure around the airlock can exist in the airlock chamber. In one embodiment, the pressure in the second state of the airlock corresponds to atmospheric pressure. In the second state of the airlock, the photomask can be transported without a pressure difference between the airlock chamber and the surrounding airlock.

[0023] The measuring apparatus according to this specification includes additional pellicles positioned in one or more other sections of the EUV beam path, thereby enabling the EUV radiation to pass through multiple pellicles in succession. This may include additional pellicles through which the EUV radiation passes exactly once. In addition to or instead of this, it may include pellicles positioned through which the EUV radiation passes twice.

[0024] The measuring device may include a spectral filter placed between the EUV radiation source and the photomask to act on the spectral composition of the EUV radiation. For inspection of the photomask, it is advantageous if the EUV radiation contains only electromagnetic radiation in a narrow wavelength range of around 13.5 nm. If the EUV radiation source also emits longer-wavelength electromagnetic radiation, for example in the EUV wavelength range, visible wavelength range, or infrared wavelength range, these components will interfere with the measurement. The filter can be designed as a bandpass filter. The passband of the band filter can be between 10 nm and 20 nm, preferably between 11 nm and 15 nm. Spectral components outside the passband, specifically longer-wavelength spectral components, are significantly attenuated.

[0025] In one embodiment, the spectral filter is a Zr filter on which EUV radiation passes through a thin layer of zirconium. The Zr filter may include a frame on which a zirconium foil is clamped. Zirconium has transmission and absorption properties suitable for this purpose. However, a thin zirconium layer has little mechanical resistance. Therefore, the Zr filter may include a grid made of a material with greater mechanical resistance on which the zirconium layer is supported. The grid may be, for example, a wire mesh made of metal wire.

[0026] Such a reinforcing structure in a Zr filter exerts an additional absorption effect that reduces the transmittance of the Zr filter to EUV radiation. In one embodiment, the Zr filter does not have a reinforcing structure. Such a Zr filter is preferably placed in an area of ​​the measuring device where the zirconium layer is not exposed to a large load.

[0027] The spectral filter can be arranged between the pellicle and the photomask. When the pellicle is between the EUV radiation source and the spectral filter, the pellicle prevents particles from moving towards the spectral filter, thus ensuring that the spectral filter is not damaged by the particles emitted by the EUV radiation source. It is advantageous if the spectral filter is arranged at a distance from the pellicle. For example, at least one EUV mirror of the illumination system may be arranged between the spectral filter and the pellicle.

[0028] In one embodiment, the spectral filter is designed to form a structural unit having a pellicle. For example, a frame holding the pellicle can simultaneously hold the spectral filter, and as a result, EUV radiation passes through the pellicle and the spectral filter. The spectral filter can be formed as a foil extending parallel to the pellicle.

[0029] The spectral filter can also be directly two-dimensionally connected to the pellicle. For example, the spectral filter can be directly attached to the pellicle as a thin layer of zirconium so that the modified pellicle has both a mechanical filtering effect and a spectral filtering effect. The layer of zirconium can be attached to the side of the pellicle facing the EUV radiation source, to the side of the pellicle facing away from the EUV radiation source, or to both sides of the pellicle. With such a homogeneous design of the pellicle and the spectral filter, the spectral filter can be made a consumable that follows the same maintenance interval as the pellicle. The replacement of this consumable can be carried out in the same way as described in the context of the unmodified pellicle. A spectral filter realized as a separate structural unit from the pellicle usually has a longer operating life than the pellicle.

[0030] The present invention also relates to a method for inspecting a photomask, in which EUV radiation emitted by an EUV radiation source is guided to the photomask via an illumination system. The EUV radiation reflected by the photomask is guided to an EUV image sensor via a projection lens so that the photomask is imaged on the image sensor. The EUV radiation passes through a pellicle disposed between the EUV radiation source and the illumination system.

[0031] The present disclosure encompasses the development of a method having the features described in the context of a measuring apparatus according to the present invention. The present disclosure encompasses the development of a measuring apparatus having the features described in the context of a method according to the present invention.

[0032] Hereinafter, the present invention will be described as an example based on advantageous embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0033] [Figure 1] It is a diagram showing a schematic view of a measuring apparatus according to the present invention. [Figure 2] It is a diagram showing the pellicle unit of the measuring apparatus of FIG. 1. [Figure 3] It is a diagram showing a schematic view of a photomask. [Figure 4] It is a diagram showing details of FIG. 1 in the case of an alternative embodiment of the present invention. [Figure 5] It is a diagram showing components of the measuring apparatus of FIG. 4. [Figure 6] It is a view seen from the perspective of FIG. 5 in an alternative embodiment of the present invention. [Figure 7] It is a view seen from the perspective of FIG. 4 in the case of an alternative embodiment of the present invention. [Figure 8] It is a view seen from the perspective of FIG. 4 in the case of an alternative embodiment of the present invention. [Figure 9] It is a view seen from the perspective of FIG. 2 in the case of an alternative embodiment of the present invention. [Figure 10] It is a view seen from the perspective of FIG. 2 in the case of an alternative embodiment of the present invention. [Modes for carrying out the invention]

[0034] The microlithography photomask 17 can be inspected using the measuring device according to the present invention.

[0035] Generally, a microlithography photomask 17 is provided for use in a microlithography projection exposure apparatus (not shown). In the microlithography projection exposure apparatus, the photomask 17 is irradiated with extreme ultraviolet radiation (EUV radiation) at a wavelength of, for example, 13.5 nm, in order to image the structure formed on the photomask 17 onto the surface of a lithography object in the form of a wafer. The wafer is coated with a photoresist that reacts to EUV radiation. A measuring device is used to check whether the measuring device meets specifications and whether or not it is contaminated.

[0036] As shown in Figure 1, the photomask 17 is positioned within the measuring apparatus so that the EUV beam path 15 emanating from the EUV radiation source 14 is guided to the photomask 17 via the illumination system 16. The illumination system 16 includes a first illumination mirror 17, a second illumination mirror 18, and a third illumination mirror 19, where the EUV beam path 16 is reflected and shaped into a beam that illuminates the inspection field 20 on the surface of the photomask 17 with uniform brightness. The inspection field 20, which is small compared to the area of ​​the photomask 17, is shown in Figure 3 in a non-scaled diagram. For example, the illumination area 20 may have dimensions of 0.5 mm × 0.8 mm. The edge length of the photomask 17 can be, for example, between 100 mm and 200 mm. Between the first illumination mirror 17 and the second illumination mirror 18 is a field diaphragm 21 used to divide the illumination area into the inspection field 20 on the surface of the photomask 17. To bring different inspection fields 20 into the region of the EUV beam path, the photomask can be moved in the XY plane using the XY positioning mechanism 37.

[0037] The EUV beam path 15, reflected by the photomask 17, continues through the projection lens 22 to the EUV camera 23 equipped with an image sensor 24. The projection lens 22 may include one or more mirrors through which the EUV radiation is reflected, and through which the inspection field 20 of the photomask 17 is imaged onto the image sensor 24 of the EUV camera 23. An aperture diaphragm 25, whose aperture corresponds to a first mirror M1, is positioned between the photomask 17 and the first mirror M1. The EUV radiation source 14, the irradiation system 15, the photomask 17, the projection lens 22, and the EUV camera 23 are housed in a vacuum housing 40 where negative pressure is maintained during the operation of the measuring device.

[0038] The EUV radiation source 14 is a plasma radiation source from which EUV radiation is emitted from the plasma at a wavelength of 13 nm. Tin is a medium that can be used to generate a plasma suitable for emitting such EUV radiation. For the purpose of generating the plasma, a laser beam can be formed to strike droplets of the medium.

[0039] The mirrors in the irradiation system 16 and the mirrors in the projection lens 22 are designed as EUV mirrors with particularly high reflectivity to EUV radiation. The optical area of ​​the EUV mirror can be formed by a high-reflectivity coating. This coating can be a multilayer coating, specifically a multilayer coating having alternating layers of molybdenum and silicon. Using such a coating, it is possible to reflect approximately 70% of the incident EUV radiation.

[0040] The projection lens 22 has a magnification of over 100. The area of ​​the image sensor 24 is larger than the area of ​​the inspection field 20 according to the magnification so that the entire image generated by the inspection field 20 of the photomask 17 can be recorded. For example, the image sensor 24 can have dimensions on the order of 100 mm to 200 mm.

[0041] Within the vacuum housing 40, a sub-chamber 33 is formed, separated from the rest of the vacuum housing 40 by an intermediate housing 29. The intermediate housing 29 has a pressure equalization channel 28 through which equal pressure is generated between the sub-chamber 33 and the rest of the vacuum housing 40. The sub-chamber 33 is treated with a purge gas to remove contaminants, and as a result, the composition and pressure of the gas in the sub-chamber 33 do not necessarily match the conditions in the rest of the vacuum housing 40.

[0042] The EUV radiation source 14 is located in the sub-chamber 33. The intermediate housing 29 has an exit aperture 31 through which the EUV radiation emitted by the EUV radiation source 14 passes out of the sub-chamber 33 towards the irradiation system 16. The exit aperture 31 is surrounded in an annular shape by the outer circumference of the intermediate housing. A pellicle unit 26 is connected to the outer circumference of the housing. As shown in Figure 2, the pellicle unit 26 includes a frame component portion 27 to which the pellicle 30 is clamped. The frame component portion 27 of the pellicle unit 26 is attached to the intermediate housing 29 of the measuring device using screw connections.

[0043] The pellicle 30 is an extremely thin film made of carbon nanotube material that allows EUV radiation to pass through easily but prevents particle passage. The irradiation system 16 is protected from particulate contaminants by the pellicle 30. Particles generated in the EUV radiation source 14 moving in the direction of the irradiation system 16 are incident on the pellicle 30 and accumulate on it.

[0044] The frame component 27 of the pellicle unit 26 can be removed from the intermediate housing 29 during maintenance operations to replace the worn pellicle 30 with a new one. For this purpose, the vacuum inside the vacuum housing 40 is released so that atmospheric pressure is present inside the vacuum housing 40. The housing opening 34 is opened to allow manual access to the inside of the vacuum housing 40. The screw connection between the frame component 27 and the intermediate housing 29 is removed so that the pellicle unit 26 can be removed from the vacuum housing 40. The new pellicle 30 can be inserted into the measuring device with the new frame component 27 and connected to the intermediate housing 29.

[0045] In the embodiments shown in Figures 4 and 5, the measuring device includes a holding device 43 that includes a frame component section 45 on which a plurality of pellicles 30 are held. The frame component section 45 is mounted on a rotary drive section 41 so that the frame component section 45 can rotate about a central axis. Depending on the rotational position of the frame component section 45, other pellicles 30 are positioned in front of the exit opening 31 of the intermediate housing 29. In the exemplary embodiments shown, the frame component section 45 carries six pellicles 30, meaning that the measuring device can continue to operate for six times the length until it becomes necessary to replace the pellicles 30 as part of a maintenance operation.

[0046] In Figures 4 and 5, the frame component 45 with the pellicles 30 is replaced manually by opening the housing opening 34 and replacing the frame component 45 with a new frame component 45 having nine pellicles. In the alternative embodiment shown in Figure 6, the frame component 45 is suspended on a pivot mechanism 44. The pivot mechanism 44 allows the frame component 45 to be moved into the airlock chamber, and as a result, the frame component 45 with the pellicles 30 can be replaced without having to release the vacuum in the vacuum housing 40.

[0047] In the alternative embodiment shown in Figure 7, a further frame portion 46, to which a zirconium foil is clamped, is connected to the frame component portion 27 of the pellicle unit 26. The zirconium foil forms a spectral filter 47 that has high transmittance at 13.5 nm and strongly attenuates other wavelengths of electromagnetic radiation, particularly longer-wavelength spectral regions up to the infrared region. The spectral filter 47 is protected from incident particles by the pellicle 30 and therefore has a longer service life. The zirconium foil is supported by a metal grid integrally connected to the foil so that the spectral filter 47 has sufficient resistance to ambient conditions prevalent in the vicinity of the EUV radiation source 14.

[0048] Figure 8 shows a variation in which the spectral filter 47 is positioned at a greater distance from the EUV radiation source 14, specifically closer to the field diaphragm 21. In this case, the operating conditions are more favorable, and therefore a pure zirconium foil without a support grid can be clamped to the frame 46. The loss of EUV radiation intensity caused by the spectral filter 47 is less than in Figure 7.

[0049] Figure 9 shows an embodiment in which the pellicle 30 itself is coated with a zirconium material. The zirconium layer forms a spectral filter 47 for EUV radiation. In Figure 9, the zirconium layer is attached to the outside of the pellicle, i.e., the side of the pellicle 30 facing the irradiation system 16 and away from the EUV radiation source 14. In Figure 10, the pellicle 30 has zirconium layers on both its outside and inside. This increases the spectral filtering effect, but the inner zirconium layer degrades more quickly because it is exposed to particles emitted by the EUV radiation source 14. In the embodiments of Figures 9 and 10, the spectral filter 47 is a consumable that is replaced along with the pellicle 30. [Explanation of Symbols]

[0050] 14 EUV radiation source 15 EUV beam path 16 Irradiation system 17 Photomask, first irradiation mirror 18. Second illumination mirror 19. Third Illumination Mirror 20. Examination field of view, irradiation area 21 Field of View Aperture 22 Projection Lens 23 EUV cameras 24 Image sensors 25 Aperture diaphragm 26 Pellicle Units 27 Frame Component Section 28 Pressure Equalization Channels 29 Intermediate Housing 30 Pellicles 31 Injection aperture 33 Subchamber 34 Housing opening 37 XY positioning mechanism 41 Rotary drive unit 43 Retaining device 44. Swivel mechanism 45 Frame Component Section 46 Frame section 47. Spectral Filters

Claims

1. A measuring device for inspecting a photomask, comprising an EUV radiation source (14), an irradiation system (16), a projection system (22), and an EUV image sensor (24), wherein EUV radiation emitted by the EUV radiation source (14) is guided to the photomask (17) via the irradiation system (16), and EUV radiation reflected by the photomask (17) is guided to the EUV image sensor (24) via the projection system (22), as a result the photomask (17) is imaged onto the EUV image sensor (24), and the pellicle (30) is positioned between the EUV radiation source (14) and the irradiation system (16) such that the EUV radiation passes through the pellicle (30) between the EUV radiation source (14) and the irradiation system (16). The vacuum chamber (40) in which the projection system (22), the irradiation system (16), and / or the EUV radiation source (14) are located is included. The EUV radiation source (14) is placed inside the sub-chamber (33) of the vacuum chamber (40). A measuring device in which the sub-chamber (33) has an ejection opening (31), and the ejection opening (31) is covered by the pellicle (30).

2. The measuring apparatus according to claim 1, wherein the pellicle (30) is positioned between the EUV radiation source (14) and the first mirror (17) of the irradiation system (16).

3. The measuring device according to claim 1, wherein the pellicle (30) is flush with the outer circumference of the housing surrounding the injection opening (31) in a sealed manner.

4. The measuring device according to claim 1 or 2, wherein the pellicle (30) is suspended on a frame (27, 45), and the frame (27, 45) is detachably connected to a support structure (29) of the measuring device.

5. The measuring device according to claim 1 or 2, comprising a holding device (43) that supports a plurality of pellicles (30), wherein the EUV radiation passes through the first pellicle (30) in a first state of the holding device (43), and the EUV radiation passes through the second pellicle (30) in a second state of the holding device (43).

6. The measuring apparatus according to claim 1 or 2, further comprising a loading mechanism (44) for removing the pellicle (30) from the vacuum chamber (40).

7. The measuring apparatus according to claim 1 or 2, further comprising a spectral filter (47) disposed between the EUV radiation source (14) and the photomask (17).

8. The measuring apparatus according to claim 7, wherein the spectral filter (47) is disposed between the pellicle (30) and the photomask (17).

9. The measuring apparatus according to claim 7, wherein the spectral filter (47) is positioned between the mirror (17) of the irradiation system (16) and the photomask (17).

10. The measuring apparatus according to claim 7, wherein the spectral filter (47) is applied to the pellicle (30) as a coating.

11. A measuring device for inspecting a photomask, comprising an EUV radiation source (14), an irradiation system (16), a projection system (22), and an EUV image sensor (24), wherein EUV radiation emitted by the EUV radiation source (14) is guided to the photomask (17) via the irradiation system (16), and EUV radiation reflected by the photomask (17) is guided to the EUV image sensor (24) via the projection system (22), as a result the photomask (17) is imaged onto the EUV image sensor (24), and the pellicle (30) is positioned between the EUV radiation source (14) and the irradiation system (16) such that the EUV radiation passes through the pellicle (30) between the EUV radiation source (14) and the irradiation system (16). A measuring device comprising a holding device (43) that supports a plurality of pellicles (30), wherein in a first state of the holding device (43), the EUV radiation passes through the first pellicle (30), and in a second state of the holding device (43), the EUV radiation passes through the second pellicle (30).

12. A measuring device for inspecting a photomask, comprising an EUV radiation source (14), an irradiation system (16), a projection system (22), and an EUV image sensor (24), wherein EUV radiation emitted by the EUV radiation source (14) is guided to the photomask (17) via the irradiation system (16), and EUV radiation reflected by the photomask (17) is guided to the EUV image sensor (24) via the projection system (22), as a result the photomask (17) is imaged onto the EUV image sensor (24), and the pellicle (30) is positioned between the EUV radiation source (14) and the irradiation system (16) such that the EUV radiation passes through the pellicle (30) between the EUV radiation source (14) and the irradiation system (16). It includes a spectral filter (47) positioned between the EUV radiation source (14) and the photomask (17), A measuring device in which the spectral filter (47) is applied as a coating to the pellicle (30).

13. A method for inspecting a photomask, wherein the EUV radiation source (14) is located in a sub-chamber (33) of a vacuum chamber (40) having an exit aperture (31) and the exit aperture (31) being covered by a pellicle (30), the EUV radiation emitted by the EUV radiation source (14) is guided to the photomask (17) via the illumination system (16), the EUV radiation reflected by the photomask (17) is guided to the EUV image sensor (24) via the projection system (22) so that the photomask (17) is imaged onto the EUV image sensor (24), and the EUV radiation passes through a pellicle (30) located between the EUV radiation source (14) and the illumination system (16).

14. A method for inspecting a photomask, wherein EUV radiation emitted by an EUV radiation source (14) is guided to a photomask (17) via an irradiation system (16), the EUV radiation reflected by the photomask (17) is guided to an EUV image sensor (24) via a projection system (22) such that the photomask (17) is imaged onto the EUV image sensor (24), the EUV radiation is positioned between the EUV radiation source (14) and the irradiation system (16), the EUV radiation passes through a first pellicle (30) supported on the holding device (43) in a first state of the holding device (43), and the EUV radiation passes through a second pellicle (30) supported on the holding device (43) in a second state of the holding device (43).

15. A method for inspecting a photomask, wherein a spectral filter (47) attached as a coating to a pellicle (30) is placed between the photomask (17) and an EUV radiation source (14), EUV radiation emitted by the EUV radiation source (14) is guided to the photomask (17) via an irradiation system (16), the EUV radiation reflected by the photomask (17) is guided to the EUV image sensor (24) via a projection system (22) so that the photomask (17) is imaged onto the EUV image sensor (24), and the EUV radiation passes through a pellicle (30) placed between the EUV radiation source (14) and the irradiation system (16).

Images