TWI887343B - Device and method for repairing a defect of an optical component for the extreme ultraviolet wavelength range - Google Patents

Abstract

The present invention relates to a device (700) for repairing at least one defect (150, 350, 550, 1450) of an optical component (100, 300, 500) for the extreme ultraviolet (EUV) wavelength range, wherein the optical component (100, 300, 500) comprises a substrate (110) and a multilayer structure (120) arranged on the substrate (110) and wherein the device comprises: (a) at least one light source (610, 1010, 1020) designed to generate a photon beam (605, 1030, 1130) in the EUV wavelength range and/or in the wavelength range of soft x-ray radiation; and (b) wherein the at least one light source (610, 1010, 1020) is furthermore designed to repair the at least one defect (150, 350, 550, 1450) by locally altering the optical component (100, 300, 500).

Description

Device and method for repairing defects in optical components in the extreme ultraviolet wavelength range

This case claims priority to German patent application No. DE 10 2020 201 482.5 filed with the German Patent and Trademark Office on February 6, 2020. The German priority application is hereby incorporated by reference in its entirety into this case.

The present invention relates to an apparatus and a method for repairing at least one defect of an optical component in the extreme ultraviolet (EUV) wavelength range, wherein the optical component for the EUV wavelength range comprises a substrate and a multi-layer structure disposed on the substrate.

As the semiconductor industry continues to increase in density, photolithography masks must image smaller and smaller structures on the wafer. In photolithography, the trend of increasing density is addressed by changing the exposure wavelength of the photolithography equipment to shorter and shorter wavelengths. Currently, the light source commonly used in photolithography equipment or lithography equipment is the argon fluoride (ArF) excimer laser, which emits a wavelength of about 193 nm.

Today, lithography systems are being developed that use electromagnetic radiation in the EUV (extreme ultraviolet) wavelength range, preferably in the range of 10 nm to 15 nm. Since there are currently no available materials that are optically transparent in the EUV range, EUV lithography systems are based on completely new beam guidance concepts using reflective optics. The technical challenges in developing EUV systems are considerable and a huge development effort is required to bring such systems to a level that is ready for industrial applications.

Significantly contributing to the imaging of smaller and smaller structures in the photoresist arranged on the wafer is the lithography mask, exposure mask, photomask, or just the mask. With each further increase in integration density, it becomes increasingly important to reduce the minimum structure size of the exposure mask. As a result, the production process of the lithography mask becomes increasingly complex and therefore more time-consuming and ultimately more expensive. Due to the tiny structure size of the patterned elements, defects cannot be excluded during the mask production. These must be repaired whenever possible.

Currently, mask defects are often repaired by electron beam induced local deposition and/or etching processes. The following are examples of literature on EUV mask repair: L. Pang et al.: “Compensation of EUV multilayer defects within arbitrary layout by absorber pattern modification”, Extreme Ultraviolet Lithography, B.M.o Fontaine and P.P. Naulleau, eds., Proc. of SPIE, vol. 7969, pp. 79691E-1 – 79691E-14; WO 2016/037 851 A1; M. Waiblinger et al.: “The door opener for EUV mask repair”, Photomask and Next Generation Lithography XIV. K. Kato, ed., “Lithography Mask Technology XIV”, Proc. of SPIE, vol. 84441, pp. 84410F-1 – 84410F-10; WO 2011 / 161 243 A1; WO 2013 / 010 976 A1; WO 2015 / 144 700 A1; G. McIntyre et al., “Through-focus EUV multilayer defect repair with micromachining”, in “Extreme Ultraviolet (EUV) Lithography IV”, P.P. Naulleau, ed., Proc. of SPIE, vol. 84441, pp. 84410F-1 – 84410F-10. SPIE, vol. 8679, pp. 86791I-1–86791I-4.

Due to the ever-decreasing structure size of patterned elements, controlling the local deposition and/or etching processes becomes increasingly challenging. Furthermore, the repair strategy must be individually adapted to the requirements of the individual manufacturing environment. Every technology-driven adaptation of the EUV mask (e.g. its material composition, dimensions, or structure) requires a re-evaluation of the established repair process, which in some cases leads to its reconstruction in a time-consuming manner.

The following references illustrate coherent light sources for the EUV wavelength range: S. Hädrich et al.: “High photon flux table-top coherent extreme ultraviolet source”, DOI: 10.1038/nphoton.2014.214, arXiv: 1403.4631; https://kmlabs.com/wp-content/uploads/2017/02/KML_XUUSTM.pdf; H. Carstens et al.: “High-harmonic generation at 250 MHz with photon energies exceeding 100 eV”, DOI: 10.1038/nphoton.2014.214, arXiv: 1403.4631; https://kmlabs.com/wp-content/uploads/2017/02/KML_XUUSTM.pdf; H. Carstens et al.: “High-harmonic generation at 250 MHz with photon energies exceeding 100 eV”, DOI: 10.1038/nphoton.2014.214, arXiv: 1403.4631; https://kmlabs.com/wp-content/uploads/2017/02/KML_XUUSTM.pdf eV), Optica, Vol. 4, No. 3, April 2016, pp. 366-369; Nature Photonics, Vol. 8, pp. 779-783 (2014).

In the technical article “Understanding thin film laser ablation: The role of the effective penetration depth and film thickness,” Physics Procedia, Vol. 56, pp. 1007-1014 (2014), M. Domke et al. study the ablation of thin metal layers from optically transparent materials with the aid of laser pulses. In the technical article “Application of actinic mask review system for the preparation of HVM EUV lithography with defect free mask,” BACUS, Vol. 33, July 2017, pp. 1-8, J. Na et al. describe the use of a High Harmonic Generation (HHG) laser system to inspect EUV masks.

The present invention solves the problem of specifying a device and a method which allow improved repair of defects in optical components in the extreme ultraviolet wavelength range.

According to an exemplary embodiment of the present invention, this problem is solved by a device as in claim 1 and by a method as in claim 15. In one embodiment, a device for repairing at least one defect of an optical component in the extreme ultraviolet (EUV) wavelength range, wherein the optical component comprises a substrate and a multilayer structure disposed on the substrate, comprising: (a) at least one light source, which is designed to generate a photon beam in the EUV wavelength range and/or in the wavelength range of soft x-ray radiation; and (b) wherein the at least one light source is further designed to repair at least one defect by locally modifying the optical component.

The device according to the invention presents an embodiment variation in the repair of components in the EUV wavelength range. In the case of previous indirect processes, an electron beam initiates a local deposition process for depositing missing material or a local etching process for removing excess material by providing a precursor gas at the reaction site. In contrast, for the direct repair of defects, the device according to the invention uses a photon beam in the EUV wavelength range and/or in the wavelength range of soft X-ray radiation. Thus, the device according to the invention overcomes the lateral resolution limitations of known repair devices caused by the use of precursor gases. Due to the short wavelength of electromagnetic radiation in the EUV range, the device according to the invention allows new dimensions of lateral spatial resolution during defect repair of optical components for the EUV wavelength range. Furthermore, during defect repair, the optical components are protected from contamination by the precursor gas and/or its components.

The EUV spectral range covers a wavelength of 10 nm to 121 nm. This corresponds to a photon energy between 124 electron Volt (eV) and 10.3 eV. In the present case, the range of soft x-ray radiation should be understood to mean a wavelength range of 0.1 nm to 10 nm. The associated photon energy range is from 12400 eV or 12.4 keV to 124 eV. The actinic wavelength (i.e. the wavelength at which the optical components are operated) preferably covers a wavelength range of 10 nm to 15 nm or an energy range of 124 eV to 82.7 eV.

At least one light source can generate a photon beam having a wavelength in the actinic wavelength range.

First, a focused photon beam in the actinic wavelength range has a high lateral spatial resolution, which makes it possible to perform very precise defect repair while reducing the risk of damaging the optical component during the repair process. Second, a light source that generates a photon beam in the actinic wavelength range can be used to record an aerial image of the defect location and/or the repaired location.

Locally modifying an optical component may include locally modifying the reflectivity of the optical component within an actinic wavelength range.

The defects of reflective optical components for the EUV wavelength range usually manifest themselves as an uneven distribution of the reflected optical intensity. In this case, more or less light may be reflected from areas of the optical component, as envisioned by the design. By means of an EUV photon beam used to locally change the reflectivity of the optical component, the uneven distribution of the reflected optical intensity from the optical component can be eliminated or at least significantly reduced.

Locally modifying an optical component may comprise locally removing material from the optical component by means of a photon beam.

Material is removed from an optical component by evaporation with the aid of a photon beam. In order to evaporate the material, firstly the optical component must be heated to the material-specific evaporation temperature; for this, an amount of energy that depends on the density and heat capacity of the material is required. Secondly, the material must be supplied with the same material-specific heat of evaporation. Focusing the EUV photon beam makes it possible to apply these specific energy densities, i.e. the energy per volume, locally. This is essentially based on two properties of the EUV photon beam. Firstly, the EUV photon beam can be focused to a very small, diffraction-limited area and, secondly, pulses of the EUV photon beam in the sub-femtosecond range can be generated, which have a very high power density.

The optical assembly may include a lithography mask for EUV wavelength range, or a reflective mirror for EUV wavelength range.

The local removal of material may include at least one of the following: removing excess material from at least one element of an absorber pattern of a lithography mask, removing material from a multi-layer structure of an optical component, and removing at least one particle from an optical component.

The light source of the device according to the invention makes it possible to repair or correct defects of excess material and defects of missing material. Defects of missing absorber material of one or more pattern elements of the lithography mask are compensated by locally removing a portion of the multilayer structure. As a result, substantially no photons are reflected from the processed portion of the lithography mask and in the spatial image or in the image in the photoresist, and the repaired locations are indistinguishable from defect-free locations.

The uneven reflection of EUV mirrors can be repaired according to the same principle. In addition, particles present on the optical component and visible in the spatial image of the optical component can be removed from the surface of the optical component by evaporation with the help of a focused EUV photon beam.

Here, as elsewhere in this case, the expression "substantially" means the measurement of the physical variable within its error limits if the measurement is carried out using a measuring instrument according to the prior art.

The at least one light source may be further configured to set an energy density of the photon beam for repairing at least one defect of the optical component.

The energy density of the photon beam can be set by means of at least two parameters. Firstly, the focusing conditions and thus the spot size of the photon beam of the light source incident on the defect or optical component can be set. Secondly, the average power of the photon beam and thus the pulse power can be varied.

The device according to the invention may further comprise a detector for detecting photons reflected from the optical component and/or an energy sensor for detecting photons reflected from the optical component and/or from at least one defect during a repair for the purpose of monitoring the repair.

If the device includes a detector, the detector can be used before, during, and after the defect repair process in order to verify the effect of the defect or the remaining part of the defect. In particular, the detector can be used in conjunction with a photon beam to check whether the defect repair was successful.

During the repair process, an energy sensor may be used to detect photons reflected from the repaired location and thereby determine changes in photon flux density, particularly a decrease in photon flux density during the repair process.

The detector may include a charge coupled device (CCD) camera for the EUV wavelength range. The energy sensor may be a CCD camera element or a detector element.

Furthermore, the device according to the invention may comprise an energy dispersive x-ray detector. The energy dispersive x-ray detector can detect photons generated by the optical component as a result of irradiation with the photon beam and/or defects in the optical component. It thus becomes possible to determine the material composition of the material treated by the photon beam.

The device according to the present invention can be designed to operate at least one light source and an energy sensor in a closed feedback loop.

Therefore, it becomes possible to monitor the repair process in real time. The probability of error in the repair process can be significantly reduced. In particular, damage to the optical component can be prevented to a large extent, and defects or whether the material of the optical component is eroded can be determined in real time.

The device according to the invention may further comprise at least one first mirror for scanning the photon beam over at least one defect of the optical component, and may comprise at least one second mirror for directing the photon beam to a region of the optical component containing the at least one defect.

According to a specific embodiment of the device of the invention comprising two reflectors, it is easier to switch the device from an inspection mode of optical components and/or defects of optical components to a repair mode for repairing defects, and vice versa.

The at least one first reflector can be designed to focus the photon beam on at least one defect of the optical component. Furthermore, the at least one first reflector can be designed to scan and focus the photon beam over the optical component and/or at least one defect of the optical component.

At least one light source may be designed to generate a coherent photon beam in the EUV wavelength range and/or in the wavelength range of soft x-ray radiation.

At least one light source may include a high harmonic generation (HHG) laser. The high harmonic spectrum of a focused femtosecond laser system extends directly into the EUV wavelength range and partially beyond to even shorter wavelengths. HHG lasers generate ultrashort EUV or x-ray pulses with a small beam divergence.

The photon beam may have a spot diameter of 0.5 nm to 200 nm, preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm, and most preferably 1 nm to 20 nm. The spot diameter represents the Full Width Half Maximum (FWHM) of the photon beam.

The photon beam may include a plurality of pulses having a pulse length in the range of 0.5 fs to 200 fs, preferably 1 fs to 100 fs, more preferably 2 fs to 50 fs, and most preferably 3 fs to 30 fs. The abbreviation "fs" stands for femtosecond.

The pulse of the photon beam may have a pulse power in the range of 0.5 nW to 2 nW, preferably 0.2 nW to 5 nW, more preferably 0.1 nW to 10 nW, and most preferably 0.05 nW to 20 nW.

The device according to the invention may further comprise a control device, which is designed to move the at least one first reflector and/or the at least one second reflector over a macroscopic distance.

By bringing at least one first or at least one second reflector into the photon beam of at least one light source, it is possible to switch back and forth between repair mode and inspection mode without moving the optical components.

The device according to the invention may comprise a Fresnel zone plate and/or the control device may be designed to move the Fresnel zone plate into and out of the photon beam.

In a second specific example, the above defined device comprises a Fresnel zone plate which enables changing between a repair mode of operation and a test mode of operation.

The control device may be further configured to set the device to a test mode using a photon beam, and/or the control device may be further configured to switch the device between a test mode and a repair mode.

The key advantage of the device according to the invention is that it firstly makes it possible to inspect optical components and/or defects of optical components and secondly allows to repair defects without having to move the optical components from a repair tool to a test tool and realign them therewith. Moreover, transferring the optical components from a first tool to a second tool usually causes the vacuum to be broken, which in addition slows down the process sequence. For the reasons mentioned, the device according to the invention drastically speeds up the repair process compared to the prior art.

The device according to the present invention may further comprise a sample holder for fixing the optical component, the sample holder being designed to rotate the optical component around at least one axis, and/or the sample holder may be further designed to displace the optical component in at least one lateral direction in order to inspect a substantially defect-free area of the optical component using a photon beam.

The repair of defects can be performed by means of a substantially normal incidence of the photon beam on the optical component. For the purpose of testing the optical component, for example for the purpose of checking whether the repair process has been successful, it is necessary that the photon beam is incident on the optical component at an angle relative to the normal direction, which is provided by the design for this purpose. This condition can be established by rotating the optical component. Thus, the best possible spatial image of the repaired area of the optical component can be obtained in the test mode.

In an alternative exemplary embodiment of the second embodiment, in order to satisfy the Bragg condition for the optical component, at least one reflector of the moving device is moved instead of the optical component.

The at least one light source may include a first light source configured to scan a focused photon beam over the at least one defect for the purpose of repairing the at least one defect, and may include a second light source configured to direct a photon beam onto a region of the optical component that includes at least one defect.

In a third embodiment, the device according to the invention comprises two separate light sources which are optimized for their respective tasks. The arrangement of the two light sources can be selected so that no part needs to be moved beyond visual distance in order to switch between the repair mode and the inspection mode.

The first and second light sources can generate a beam of photons within the actinic wavelength range of the optical component. The first light source can generate a beam of photons outside the actinic wavelength range, and the second light source can generate a beam of photons within the actinic wavelength range.

During repair and/or during inspection, the optical component may include a thin film through which the photon beam is radiated.

One advantage of the device according to the invention is that the device can perform both a repair process and an inspection process of an optical component, wherein the optical component comprises a film. Thus, defects are inspected in the way they manifest themselves during operation of the optical component. Furthermore, the repair process is performed under conditions similar to those under which the optical component is used. A further advantage is that the repair can be performed through the film, wherein after the end of the repair process, the film remains fully functional and therefore does not have to be changed. Moreover, the film mounted on the optical component prevents material removed from the optical component from being deposited in the device or at a remote location of the optical component and thereby contaminating the optical component. Material removed by the deposited mask on the film does not adversely affect or only adversely affects to a very small extent the exposure process to be performed by the mask.

A method for repairing at least one defect of an optical component in the extreme ultraviolet (EUV) wavelength range, wherein the optical component comprises a substrate and a multilayer structure arranged on the substrate, the method comprising the following steps: (a) generating a photon beam in the EUV wavelength range and/or in the wavelength range of soft x-ray radiation; and (b) configuring the photon beam so that the at least one defect is repaired by locally modifying the optical component.

Setting the photon beam may include at least one of the following groups: focusing the photon beam, changing a pulse power of the photon beam, changing a polarization of the photon beam, and changing an incident angle of the photon beam relative to a normal direction of the optical component.

The method according to the present invention may further comprise the step of switching between repairing at least one defect of the optical component with a photon beam and inspecting the optical component and/or at least one defect of the optical component with a photon beam.

The method according to the present invention may further include at least one of the following steps: (a) inspecting at least one defect with a photon beam and/or inspecting a substantially defect-free reference position with a photon beam; (b) determining a repair form for at least one detected defect if at least one detected defect exceeds a predetermined threshold; (c) repairing at least one defect with a photon beam; (d) inspecting a repaired position of an optical component with a photon beam; and (e) repeating steps a. and b. if a remaining residue of at least one defect exceeds a predetermined threshold.

An apparatus according to any of the above described aspects may be designed to perform the method steps of any of the above explicitly described methods.

Finally, a computer program comprises instructions which, when executed by a computer system, cause the computer system to perform the method steps described above.

The following is a more detailed description of currently preferred embodiments of the apparatus and method for repairing one or more defects of a lithography mask in the extreme ultraviolet (EUV) wavelength range according to the present invention. However, the apparatus and method according to the present invention are not limited to the embodiments discussed below. Rather, they can generally be used to repair defects of optical components in the extreme ultraviolet (EUV) wavelength range. In addition to EUV masks, embodiments of optical components for the EUV wavelength range include EUV mirrors, i.e., mirrors for the EUV wavelength range.

FIG. 1 schematically presents a side view of a section of a lithography mask 100 for the EUV wavelength range in the upper image 105. Hereinafter, the lithography mask 100 for the EUV wavelength range is also referred to as EUV mask 100. The exemplary EUV mask 100 in FIG. 1 is designed for exposure wavelengths or actinic wavelengths in the region of 13.5 nm. The EUV mask 100 has a substrate 110 made of a material with a low coefficient of thermal expansion, such as quartz. Other dielectrics, glass materials, or semiconductor materials can also be used as substrates for EUV masks, such as ^ZERODUR® , ^ULE® , or ^CLEARCERAM® . The back side or back side surface of the substrate 110 of the EUV mask 100 is used to hold the substrate 110 during production of the EUV mask 100 and during operation of the EUV mask 100 in an EUV lithography apparatus. Preferably, a thin conductive layer for holding the substrate on an electrostatic chuck (ESC) is applied to the back side of the substrate 110 (not shown in FIG. 1 ). In an alternative embodiment, the EUV mask 100 has no conductive layer on the back side of the mask substrate 110 and the EUV mask 100 is fixed by means of a vacuum chuck (VC) during its operation in the EUV lithography apparatus.

A multilayer film or multilayer structure 120 containing 20 to 80 pairs of alternating molybdenum (Mo) and silicon (Si) layers (hereinafter also referred to as MoSi layers) is deposited on the front side of the substrate 110. The Mo layer has a thickness of 4.15 nm, while the Si layer has a thickness of 2.80 nm. To protect the multilayer structure 120, a capping layer 130 (e.g. made of silicon dioxide) having a thickness of typically about 7 nm is applied on the topmost silicon layer. Other materials, such as ruthenium (Ru), can also be used to form the capping layer 130. Instead of molybdenum, layers composed of other elements with high mass numbers, such as cobalt (Co), nickel (Ni), tungsten (W), rhodium (Re), zirconium (Zn), or iridium (Ir), may also be used for the MoSi layer. For example, the deposition of the multilayer structure 120 may be performed by ion beam deposition (IBD).

An absorption layer is deposited on the cover layer 130 of the EUV mask 100. Suitable materials for the absorption layer are in particular Cr, titanium nitride (TiN), and/or tantalum nitride (TaN). An antireflection layer, for example of tantalum oxynitride (TaON), can be applied to the absorption layer (not shown in FIG. 1 ). The absorption layer is structured, for example by means of an electron beam or a laser beam, so that the structure of the absorption pattern element is generated from the entire area of the absorption layer. The section in FIG. 1 shows a pattern element 140 that is wider than envisaged by the design. Excess material 150 is a defect 150 of the EUV mask 100. Due to the defect 150, no EUV photons or at least many fewer EUV photons than envisaged by the design are reflected from the area of the excess material 150.

The defect 150 of excess absorber material can be removed by means of an EUV laser beam 160 or an EUV photon beam 160. The EUV photon beam can be generated, for example, by ultrashort pulses of a pump laser that are focused at or near the focus and exposed to a gas flow. The pump laser used can be, for example, a titanium sapphire laser, which preferably emits femtosecond light pulses at a wavelength of 800 nm. For example, noble gases such as krypton or xenon are currently preferably used as gases for generating the EUV photon beam 160. Starting from a two-dimensional power density of the pump laser beam of about 10 ¹⁴ W/cm ² or a photon flux density of about 10 ¹⁴ J/(cm ² ·s), high harmonics are generated in the gas flow. The generation of high harmonic waves is known in the technical field as high harmonic generation (HHG). At the extremely high intensities indicated above, the electric field of the pump beam reaches field strengths that are equivalent to the electric field in individual atoms. The electric field inside the atom is deformed or disturbed by the electric field at the focus of the pump laser beam, so that the electron can overcome its bond to the atom and can tunnel into the continuum. The free electrons are then accelerated in the laser field by the absorption of multiple or large numbers (up to hundreds) of photons. Immediately after the electric field of the laser changes sign, some of the electrons are decelerated in the electric field of the atom from which they originated and emit their energy in the form of one or several high-energy photons. The highest photon energy that can be generated by this principle is limited by the maximum number of photons absorbed by the electrons during the acceleration phase. During the oscillation duration of the pump laser light, two coherent ultrashort sub-femtosecond pulses with small beam divergence are generated.

From the diversity of the generated harmonics, it is possible to select harmonics in or closest to the actinic wavelength range, for example at 13.5 nm, with the aid of an EUV spectrometer. In the actinic wavelength range, HHG laser systems currently achieve average powers of about 1 µW, which, given an assumed photon energy of 100 eV per photon, corresponds to a photon flux of about 7·10 ¹⁰ photons/second.

Then, assume that 10% of the EUV photons can be concentrated in a spot diameter of 100 nm. This corresponds to a photon flux density of about 7·10 ⁶ photons/(nm ² ·s). This corresponds to an energy flux density of about 10 ³ J/cm ² and is therefore very significantly higher than the threshold energy density for femtosecond laser pulses. As already explained above, two mutually reinforcing factors contribute to the rather large energy flux density of the photon beam of an EUV laser, such as an HHG laser system. Firstly, due to the very short wavelength of EUV photons, they can be focused on a small area. Secondly, a single EUV photon carries a lot of energy compared to photons from the visible spectrum.

In the article "Metal Ablation with Short and Ultrashort Laser Pulses", Physics Procedia 12 (2011), pp. 230-238, KH Leitz et al. study material ablation with the aid of microsecond, nanosecond, picosecond, and femtosecond laser pulses. For femtosecond laser pulses, the authors indicate a threshold energy density of 1.25 J/cm ² for laser radiation close to the visible spectrum.

The interaction region of the EUV photon beam 160 is shown as component symbol 170 in Figure 1. The interaction between the photons of the femtosecond pulse and the matter can no longer be explained by the traditional erosion model (which takes into account the processes of heat conduction, melting, evaporation, and plasma formation). The non-traditional erosion model that explains the ultrafast interaction between the photon beam and the matter is based on the following assumption: When the ultrashort laser pulse acts on the matter, the electrons or electron gas in the metal are no longer in thermal equilibrium with the atomic nuclei. On the femtosecond time scale, the electron cloud cannot immediately emit its energy to the lattice of the atomic nuclei. Locally very high pressures, densities, and temperatures occur under the action of the femtosecond laser pulse and accelerate the ionized material of the defect 150 to high speeds. Due to the short interaction time, the material of defect 150 cannot continue to evaporate, but is transformed into a superheated liquid state. The superheated liquid coalesces into a high-pressure mixture of droplets and rapidly expanding vapor. The droplets are shown as component symbol 180 in FIG. 1 .

An ultra-short pulse of the EUV photon beam 160 is scanned over the defect 150. In this case, one, a plurality, or a large number (e.g., hundreds) of pulses may be directed to the same location of the defect 150 before focusing the photon beam 160 on the new location of the defect 150. To better address the defect 150, the photon beam 160 and/or the EUV mask 100 may be tilted from the normal direction if necessary.

FIG. 2 schematically shows an increase in the reflection of EUV photons from the area of a defect 150 of an EUV mask 100. A position of an EUV mask 100 with an identical arrangement of pattern elements 140 but without a defect location 150 or a defect position 150 is considered as a reference. The defect-containing area of the EUV mask 100 is related to this reference position. Due to the excess absorber material of the defect 150 being removed from the cover layer 130 of the EUV mask by means of the EUV photon beam 160, the optical intensity reflected from the EUV mask increases locally. As soon as the radiation reflected from the area of the defect 150 reaches the level of the reference area, the repair process is stopped by switching off or interrupting the EUV photon beam 160.

The repair process can be monitored in a number of ways. Firstly, the optical intensity in the EUV wavelength range reflected from the defect-containing area can be measured permanently during the repair process by means of energy sensors. This is illustrated in FIG. 2 . However, it is also possible to interrupt the repair process from time to time and monitor the optical reflection from the area of the defect 150 by means of a large-area EUV photon beam and a detector. Finally, in order to analyse the energy-selective x-ray photons generated by the defect 150 during the repair process, an energy-dispersive x-ray detector can also be used. This allows the material composition of the defect 150 to be analysed and it can be determined when the EUV photon beam 160 reaches the cover layer 130 of the EUV mask.

The upper image 305 in FIG. 3 shows a side view of a section of an EUV mask 300 having a defect 350 of missing absorber material of a pattern element 340. The lower image 355 presents an associated top view. The defect 350 is characterized by the fact that EUV photons are reflected from areas of the EUV mask 300 that should appear dark. The defect 350 of missing absorber material can be repaired in various ways. First, the multi-layer structure 120 below the defect area 350 can be etched by means of a focused EUV photon beam 360. This ensures that no EUV photons can be reflected from the area of the defect 350 anymore. Element symbol 370 shows the local interaction area of the EUV photon beam 360 with the material of the multi-layer structure 120 of the EUV mask 300.

In order to repair the defect 350, it may also be sufficient to remove only a portion of the multilayer structure 120 in the region of the defect 350. The uppermost layer of the multilayer structure 120 usually contributes primarily to the reflection of EUV photons. Furthermore, in particular for small-area defects 350 with missing absorber material, it may be sufficient to locally melt the surface of the multilayer structure 120 in the region of the defect, so that the planarity of the cover layer 130 and, if appropriate, the uppermost layer of the multilayer structure 120 is locally disturbed or destroyed.

3 can also be used to repair local excesses of optical intensity in mirrors for the EUV wavelength range (not shown in FIG3 ). Locally increased reflectivity of EUV mirrors can be caused by defects in the multilayer structure 120 and/or the substrate 110 .

FIG. 4 schematically illustrates the change in the local reflected optical intensity of the EUV mask 300 as a result of performing the repair process illustrated in FIG. 3 . In a manner similar to FIG. 2 , the intensity reflected from the area of the defect 350 is normalized to the defect-free area of the EUV mask 300 using an equivalent pattern. Due to the defect 350 of missing absorber material, EUV photons are reflected from areas of the EUV mask 300 that should actually be dark. Therefore, the defect 350 causes a local increase in reflectivity of the EUV mask 300. Repairing the defect 350 using an EUV photon beam 360 reduces the local excess of optical intensity. The repair process of the EUV mask 300 is terminated immediately after the radiation reflected from the area of the defect reaches the reference level.

The upper image 505 in FIG. 5 presents a side view of a cross section of a section of an EUV reticle 500 having particles 550 on a capping layer 130 of a multi-layer structure 120. The lower image 555 further presents a related top view. The particles 550 shield a portion of the multi-layer structure 120 from incident EUV photons, which has the effect that the EUV reticle 500 reflects fewer photons from the area of the defect 550 (i.e., the particle 550) than from a non-defective reference area. The particles 550 can be etched from the capping layer 130 of the EUV reticle 500 by means of a focused photon beam 560. Element symbol 570 further illustrates the interaction region of the EUV photon beam 560 and the particles 550.

In order to analyze the material composition of the particle 550 in situ (not shown in FIG. 5 ), an energy dispersive x-ray detector is used during the stripping process to advantage when removing the particle 550. Thus, the end of the stripping process can be monitored for the particle 550. Moreover, the source of the particle 550 can often be inferred from its material composition. If this is achieved, the source of contamination can be eliminated or at least drastically reduced, so that future repair processes can be avoided.

Schematic diagram 695 in FIG. 6 shows a side view of a section of EUV reticle 600. EUV reticle 600 can be one of defective EUV reticle 100, 300, or 500. That is, defect 650 of reticle 600 can be one of defects 150, 350, or 550, and absorber pattern 640 can include one of pattern elements 140, 340, 540 of EUV reticle 100, 300, or 500. Furthermore, interaction region 670 can be one of interaction regions 170, 370, or 570. Furthermore, FIG. 6 shows a first exemplary embodiment of an apparatus 700 for repairing defect 650 and inspecting EUV reticle 600 (or, in general, optical components 100, 300, 500 for use in the EUV wavelength range).

FIG6 schematically shows a part of the process for repairing a defect 650. The device 700 comprises a light source 610 for the EUV wavelength range, which generates a collimated EUV photon beam 605. Furthermore, the device 700 comprises a control device 750 connected to the EUV light source 610 via a connection 710. The EUV photon beam 605 generated by the EUV light source 610 is focused on the defect 650 of the EUV mask 600 by a first imaging EUV mirror 620. The first imaging EUV mirror 620 is connected to the control device 750 of the device 700 via a connection 730.

While the focused EUV photon beam 630 is scanned over the defect 650 by the control device 750, the energy sensor 690 detects EUV photons 680 reflected from the region of the defect 650. The energy sensor 690 is also connected to the control device 750 of the device 700 via a connection 720. With the aid of the energy sensor 690, the control device 750 can operate the EUV laser system 610 or the EUV light source 610 in a closed feedback loop. As schematically shown in Figures 2 and 4, progress in defect elimination can be inferred based on changes in the reflected optical intensity detected by the energy sensor 690 as a function of time.

FIG. 7 schematically shows an implementation of a portion of a process for inspecting the EUV mask 600 of the first exemplary embodiment shown in FIG. 6 by means of the apparatus 700. For the purpose of inspecting the defect region 650 of the EUV mask 600, the control device 750 of the apparatus 700 moves the first imaging EUV mirror 620 out of the collimated EUV photon beam 605 of the EUV light source 610. Thus, the EUV photon beam 605 can be incident on the second imaging EUV mirror 660. The second imaging EUV mirror 660 directs the EUV photon beam 605 as an expanded photon beam 760 onto the region of the EUV mask 600, which includes the region containing the defect 650. In the exemplary embodiments shown in FIGS. 6 and 7, the defect 650 includes a particle 550. The multi-layer structure 120 of the EUV mask 600 reflects a portion of the incident EUV photons of the light beam 760 in the direction of a detector 780. In the exemplary embodiment illustrated in Figure 7, the detector 780 comprises a CCD camera.

FIG8 presents a second exemplary embodiment of an apparatus 700 according to the present invention. The second exemplary embodiment is explained based on an embodiment of repairing one of the defects 650 of an EUV mask 600. The apparatus 700 for repairing the defect 650 comprises the EUV light source 610 of the first exemplary embodiment. The aforementioned light source is in turn connected to the control device 750 via the connection 710. Furthermore, the control device 750 is connected to a non-imaging EUV mirror 820 via the connection 810, to a Fresnel zone plate 850 via the connection 855, and to an energy sensor 690 via the connection 865. The EUV photon beam 605 generated by the EUV light source is guided as the EUV photon beam 830 onto the Fresnel zone plate 850 by the EUV mirror 820. The Fresnel zone plate 850 focuses the EUV photon beam 840 passing therethrough onto the defect 650 of the EUV mask 600. During the repair, EUV light 860 reflected from the defect region 650 of the EUV mask 600 is detected by the energy sensor 690. Based on the EUV radiation 860 detected by the energy sensor (in a manner similar to the first exemplary embodiment), the control device 750 of the device 700 may operate the EUV light source 610 in a closed feedback loop (not shown in FIG. 8 ).

FIG9 shows the second part of the process of the second exemplary embodiment, namely, the inspection of the EUV mask 600 using the EUV photon beam 605 of the EUV light source 610. For the purpose of inspecting the EUV mask 600, the control device 750 moves the Fresnel zone plate 850 out of the beam path of the EUV photon beam 920. The photon beam 830, which is no longer focused, irradiates the region of the defect 650 on the multi-layer structure 120 of the EUV mask 600. In order for the incident EUV photon beam 830 to satisfy the Bragg reflection condition of the multi-layer structure 120 of the EUV mask 600 as much as possible, the control device 750 rotates the sample holder on which the EUV mask 600 is arranged. The rotation of the EUV mask 600 is shown as the component symbol 910 in FIG9. The sample holder (referred to as: carrier) is not shown in FIG9.

As shown by the remaining defect residues 650 in FIG. 9 , if further repair steps are required, the control device 750 rotates the EUV mask 600 back to its initial position again and introduces the Fresnel zone plate 850 into the beam path of the EUV photons 830 again so that the remaining defect residues 650 can continue to be repaired.

The schematic diagram 1000 in FIG10 shows a third exemplary embodiment of the apparatus 700 according to the present invention. The third exemplary embodiment in FIG10 comprises a first EUV light source 1010 and a second EUV light source 1020, which are connected to the control device 750 via connections 1015 and 1025. Furthermore, the control device 750 is connected to the detector 690 via connection 695. The third exemplary embodiment is also explained based on repairing the defect 650 of the EUV mask 600.

The repairing portion of the third exemplary embodiment of the apparatus 700 according to the present invention is schematically presented in Fig. 10. For the purpose of repairing the defect 650, the second EUV light source 1020 radiates the focused photon beam 1030 on the defect 650 of the EUV mask 600 or scans the focused photon beam 1030 over the defect 650.

After a predetermined time, the repair process is interrupted and the processed or repaired position 650 of the EUV mask 600 is inspected. For this purpose (as schematically shown in FIG. 11 ), the focused photon beam 1030 of the second EUV light source is stopped. Afterwards, the first EUV light source 1010 is activated, which directs a collimated EUV photon beam 1130 onto the region of the EUV mask 600 containing the defect 650. In this case, the area of the beam spot is selected with a value that does not reach the threshold density for melting the multi-layer structure 120 of the EUV mask 600. According to the estimates indicated above, this requires a spot diameter of about 5 μm or more.

In Figures 10, 11, and the subsequent Figure 12, the first EUV light source 1010 and the detector 690 are arranged relative to the normal direction of the EUV mask 600 so as to meet the Bragg reflection conditions for the actinic wavelength range of the EUV mask 600 as much as possible. The third embodiment has a particular advantage: no part of the device 700 needs to be moved beyond the visual distance in order to switch between the repair mode and the inspection mode of the device 700. The first EUV light source 1010 and the second EUV light source can be designed so that a single EUV light source simultaneously generates both the focused EUV photon beam 1030 and the EUV photon beam 1130. In this embodiment, the first EUV light source 1010 and the second EUV light source 1020 only provide a beam shaping device and/or a beam guiding device.

12 shows an exemplary embodiment of the apparatus 700, wherein two light sources 1010 and 1020 simultaneously radiate photons 1030 and 1130 onto the defect 650 or into the area around the defect 650. In this exemplary embodiment, it is advantageous if the first EUV light source 1010 radiates a beam of EUV photons 1130 within the actinic wavelength range onto the EUV reticle 600, and the second EUV light source 1020 generates photons outside the actinic wavelength range of the EUV reticle 600. This ensures that substantially no EUV photons from the second EUV light source 1020 can reach the detector 690. This prevents the local reflected optical intensity detected by the detector 690 from being corrupted.

FIG. 13 reproduces FIG. 6 , with the difference that the pellicle 1310 is mounted on the EUV mask 600. The distance between the EUV pellicle 1310 and the cover layer 130 of the EUV mask is in the range of 2 to 3 mm. Both the repair process and the inspection process of the EUV mask 600 are performed through the pellicle 1310. Therefore, the effect of the defect 650 of the EUV mask 600 can be inspected under the conditions that prevail during the actual operation of the EUV mask 600. Furthermore, the removal of the pellicle 1310 for defect correction and the reinstallation of the pellicle 1310 after defect repair and the possible damage to the mask 600 bonded thereto can be avoided.

The repair process and/or inspection process of the EUV mask 600 as described with reference to FIGS. 8 to 12 can also be performed with the pellicle 1310 mounted on the EUV mask. This has two advantages. First, the repair can be performed under the operating conditions of the mask, and second, contamination of the optical components of the repair device can be prevented. In contrast, the material removed from the mask and deposited on the pellicle mounted on the mask will hardly interfere with the exposure process to be performed by the mask.

The following explanation of embedding the repair process performed by means of the device 700 into the work sequence of defect analysis and defect correction of the EUV mask 100, 300, 500 is explained with reference to Figures 14 to 16. Before the defects 150, 350, 550 can be repaired, they must first be confirmed and then analyzed. For example, EUV-AIMS ^TM (Aerial Image Measurement System) can be used to analyze the defects 150, 350, 550. Figure 14 shows a top view of a section of the strip structure 1420 with a defect 1450 in the left image 1410. The right image 1415 in Figure 14 presents a top view of a section of a defect-free reference strip structure 1425. Both images are recorded by EUV-AIMS ^TM . From the left image, the defect 1450 can be analyzed in detail. Analysis of defect 1450 may include comparing defect-containing strip structure 1420 to defect-free reference strip structure 1425. A repair profile for defect 1450 is established from a detailed analysis of defect 1450. The repair profile provides, for example, defect type, defect size, defect location relative to one or more pattern elements, pattern type of EUV mask, and scanner exposure settings during operation of the mask. Furthermore, the repair profile specifies the coordinates of the size of the defect on the EUV mask and indicates the energy dose to be applied to repair the defect relative to the defect coordinates. The repair profile determined for defect 1450 is transmitted to device 700 for repairing the defect.

FIG15 schematically presents a repair of the defect 1450 of FIG14 by means of one specific example of the apparatus 700. The upper left image 1510 of FIG15 substantially shows a section of the left image of FIG14, imaged, for example, by the EUV photon beam 760, 830, 1130 of the apparatus 700 in the inspection mode. The apparatus 700 "sees" the defect 1450 of FIG14 in the inspection or imaging mode. The upper right image 1515 shows the reference stripe structure 1525 of FIG14, recorded by the EUV photon beam 760, 830, 1130 of the apparatus 700.

The repair process of the defect 1450 by means of the EUV photon beam 630, 840, 1030 of the apparatus is shown by arrow 1580 in FIG15. As explained above, the apparatus 700 obtains a repair pattern for the defect 1450 from a defect inspection tool (e.g., EUV-AIMS ^™ ). For the purpose of repairing the defect 1450, the EUV photon beam 630, 840, 1030 (as predetermined by the repair pattern) is scanned over the defect 150, 350, 550, 1450.

In order to analyze the remaining defect residues, the repair of defect 1450 may be interrupted from time to time. The interruption of the repair may be performed periodically or predetermined by the repair form.

15 shows a section of the stripe structure 1530 of the upper left image 1510 after defect repair has been completed. The repaired location is indicated by reference symbol 1560 in the stripe structure 1530 of the partial image 1550. The lower right image 1555 reproduces the reference stripe structure 1525 of the upper right image 1515 again.

FIG16 shows an aerial image of an image of the repaired section 1530 of the lower left image 1550 in FIG15, recorded by means of EUV-AIMS ^™ . In the local image 1610, the repaired position 1560, the repaired location 1560, or the repaired area 1560 is identified. For comparison purposes, the right image 1615 presents the reference stripe structure 1425 of the local image 1415. The juxtaposed view in FIG16 reveals that the apparatus 700 has repaired the defect 1450 to a certain extent, such that the defect is no longer visible in the aerial image of EUV-AIMS ^™ .

FIG. 17 shows a flow chart 1700 of an overall sequence for defect repair of an optical component 100, 300, 500 for the EUV wavelength range. The method starts at block 1705. A first step 1710 consists in recording an image of a defect 150, 350, 550, 1450 or a defect location 150, 350, 550, 1450 of the optical EUV component 100, 300, 500. This step is typically performed with the aid of an inspection tool (e.g., EUV-AIMS ^TM , etc.). In an alternative embodiment, the inspection tool uses a charged particle beam (e.g., an electron beam). Then, in step 1715, a reference image of a defect-free reference location is also recorded with the aid of an inspection tool. Step 1715 is an optional step. This is shown in the dashed box in Figure 17.

Then, decision block 1720 is made as to whether it is necessary to repair the defect 150, 350, 550, 1450 based on the image determined by the defect 150, 350, 550, 1450 (optionally with the aid of a reference image). If it is not necessary, the method jumps to block 1775 where a decision is made as to whether the EUV reticle 100, 300, 500 has further defects 150, 350, 550, 1450. If this is not the case, the method ends at step 1780 and the optical EUV assembly 100, 300, 500 can be used. If the optical EUV assembly 100, 300, 500 includes an EUV reticle 100, 300, 500, the EUV reticle can be used in a scanner. If a further defect 150, 350, 550, 1450 is present on the EUV reticle 100, 300, 500, the method jumps to block 1710, where an image of the next defect 150, 350, 550, 1450 is recorded by EUV-AIMS ^™ .

If repair of the defect location 150, 350, 550, 1450 is necessary, the method jumps to block 1725, where the defect location 150, 350, 550, 1450 or an image of the defect 150, 350, 550, 1450 is recorded by the device 700 or the repair device 700 in the inspection mode. Then, the type of repair for the defect location 150, 350, 550, 1450 is determined in block 1730. The type of repair for the defect 150, 350, 550, 1450 can be determined using the image recorded by the inspection tool in step 1710 (optionally combined with a reference image). Alternatively, the type of repair can be determined from one or more images recorded by the device 700 or the repair device 700 in the inspection mode. Alternatively, the images of the defect locations 150, 350, 550, 1450 measured in steps 1710 and 1725 may be considered in combination to determine the type of repair for the defect 150, 350, 550, 1450.

At decision block 1735, a decision is made as to whether treating or repairing the defect 150, 350, 550, 1450 is expected to result in a local increase 1740 or a local decrease 1745 in reflectivity of the EUV reticle 100, 300, 500. If the defect 150, 350, 550, 1450 is an excess material defect 150, 550, then at block 1750, excess absorber material of one or more pattern elements 140 or excess material of particles 550 is removed from the EUV reticle 100, 500 by stripping using a photon beam 630, 840, 1030.

If the desired change in defect repair is a local decrease in reflected optical intensity, then at block 1755, the multi-layer structure 120 of the EUV mask 300 is processed using the photon beam 630, 840, 1030 in order to strip a portion of the multi-layer structure 120 of the EUV mask 100, 300, 500 or at least reduce the planarity.

Two processes 1750 and 1755 direct the method to block 1765, which involves recording images of the repaired positions 150, 350, 550, 1450 of the EUV masks 100, 300, 500 using the inspection mode of the device 700. In decision block 1770, a decision is made as to whether to conclude repairing defects 150, 350, 550, 1450. If this is not the case, the method jumps to block 1725 where images of the remaining defect residues are recorded by the repair device 700 in inspection mode. If the fact that the conclusion of repairing defects 150, 350, 550, 1450 is determined in decision block 1770, the method jumps to decision block 1775. Decision block 1775 is to determine whether the EUV mask 100, 300, 500 has further defects 150, 350, 550, 1450. If so, the method jumps to block 1710 and measures the image of the next defect. If no further defects 150, 350, 550, 1450 exist on the mask 100, 300, 500, the method ends at block 1780.

Finally, the flowchart 1800 in FIG. 18 shows the necessary steps for repairing at least one defect 150, 350, 550, 1450 of an optical component 100, 300, 500 in the extreme ultraviolet wavelength range according to the method of the present invention, the optical component comprising a substrate 110 and a multilayer structure 120. The method starts at step 1810. The first step 1820 consists in generating a photon beam 605, 1030, 1130 in the EUV wavelength range and/or in the wavelength range of soft x-ray radiation. Block 1830 consists in setting the photon beam 605, 1030, 1130 so that at least one defect 150, 350, 550, 1450 is repaired by locally modifying the optical component 100, 300, 500. Finally, the method ends at block 1840.

100,300,500,600:EUV mask 105,305,505:Upper image 110:Substrate 120:Multi-layer structure 130:Coating layer 140,340,540:Pattern element 150:Defect of excess material 160,360,560:EUV photon beam 170,370,570,670:Interaction zone 180:Droplets 350:Defect of missing material 355,555:Lower image 550:Defect of particles 605:Collimated EUV photon beam 610:EUV Light source 620: First imaging EUV mirror 630: Focusing EUV photon beam 640: Absorber pattern 650: Defect 660: Second imaging EUV mirror 680: EUV photons 690: Energy sensor 695: Schematic diagram 700: Repair device 710,720,730,810,855,865,1015,1025: Connection 750: Control device 760: Expanding photon beam 780: Detector 820: Non-imaging EUV mirror 830,840: EUV photon beam 850 :Fresnel zone plate 860:EUV light 910:Rotation 920:Move out 1000:Schematic diagram 1010:First EUV light source 1020:Second EUV light source 1030:Focused EUV photon beam 1130:Collimated EUV photon beam 1310:Thin film 1410:Left image 1415:Right image 1420:Defective strip structure 1425:Defect-free reference strip structure 1450:Defect 1510:Upper left image 1515:Upper right image 1525:Reference strip structure 1530 : Strip structure 1550: Lower left image 1555: Lower right image 1560: Repaired position 1580: Arrow 1610: Partial image 1615: Right image 1700,1800: Flowchart 1705,1710,1715,1725,1730,1750,1755,1765,1780,1810,1820,1830,1840: Block/step 1720,1735,1770,1775: Decision block 1740: Local increase 1745: Local decrease

The following detailed description is a currently preferred exemplary embodiment of the present invention with reference to the drawings, in which: FIG1: schematically shows a section of a cross-section of a side view of a mask for use in the extreme ultraviolet wavelength range (EUV) in the upper image, wherein the pattern element has a defect in the form of excess absorber material, and presents a top view of the side view of the upper image in the lower image; FIG2: schematically shows the change of the normalized intensity during the repair of the defect of the excess absorber material of the EUV mask in FIG1; FIG3: schematically shows a section of a cross-section of a side view of an EUV mask in the upper image, wherein the pattern element has a defect in the form of missing absorber material, and presents a top view of the side view of the upper image in the lower image; FIG4: Schematic illustration of the change in normalized intensity during the repair of a defect of missing absorber material of an EUV mask in FIG3; FIG5: schematically showing a section of a side view of an EUV mask with a defect in the form of a particle in the upper image, and presenting a top view of the side view of the upper image in the lower image; FIG6: schematically presenting a section through an EUV mask with a defect and a first exemplary embodiment of an apparatus for repairing a defect, wherein the apparatus is operated in a repair mode; FIG7: a reproduction of FIG6, but wherein the apparatus is operated in an inspection mode; FIG8: a second exemplary embodiment of an EUV mask with an apparatus for repairing a defect in FIG6, wherein the apparatus is operated in a repair mode; FIG9: a reproduction of FIG8, but wherein the apparatus is operated in an inspection mode; FIG10: FIG. 6 shows a third exemplary embodiment of an EUV mask having an apparatus for repairing defects, wherein the apparatus is operated in a repair mode; FIG. 11: a reproduction of FIG. 10, but wherein the apparatus is operated in an inspection mode; FIG. 12: presents the apparatus of FIG. 10 and FIG. 11, wherein the apparatus is operated in a repair mode and in an inspection mode simultaneously; FIG. 13: shows the configuration of FIG. 6, wherein a pellicle is mounted on an EUV mask during a repair process; FIG. 14: presents a stripe structure of an EUV mask, wherein a defect is in the left image and a defect-free reference stripe structure is in the right image, wherein both local images were recorded using EUV-AIMS ^TM ; FIG. 15: The upper image shows the stripe structure of the EUV mask in the partial image of Figure 14 (as it appears in the image generated by the repair device in the inspection mode), the lower left image shows the upper left image after the defect repair process is completed, and the lower right image reproduces the reference stripe structure of the upper right image; Figure 16: shows the image in Figure 14 after the defect repair; Figure 17: shows a flow chart of the repair process for optical components in the EUV wavelength range; and Figure 18: shows a flow chart of the method for repairing defects of optical components in the EUV wavelength range according to the present invention.

110: Base material

120:Multi-layer structure

130: Covering layer

600:EUV mask

605: Collimated EUV photon beam

610:EUV light source

620: The first imaging EUV mirror

630: Focusing EUV photon beam

640:Absorbent pattern

650: Defects

660: Second imaging EUV mirror

670: Interaction zone

680:EUV Photons

690:Energy sensor

695: Schematic diagram

700:Repair device

710,720,730:Connection

750: Control device

Claims (19)

A device (700) for repairing at least one defect (150, 350, 550, 1450) of an optical component (100, 300, 500) within the extreme ultraviolet wavelength range, wherein the optical component (100, 300, 500) comprises a substrate (110) and a multilayer structure (120) disposed on the substrate (110), comprising: a. At least one light source (610, 1010, 1020) designed to generate a photon beam (605, 1030, 1130) within the EUV wavelength range and/or within the wavelength range of soft x-ray radiation; b. wherein the at least one light source (610, 1010, 1020) is further designed to repair the at least one defect (150, 350, 550, 1450) by partially changing the optical component (100, 300, 500); and c. a detector (780) for detecting photons reflected from the optical component (100, 300, 500). A device (700) as claimed in claim 1, wherein locally changing the optical component (100, 300, 500) comprises locally changing a reflectivity of the optical component (100, 300, 500) within a range of actinic wavelengths. A device (700) as claimed in claim 1, wherein locally altering the optical component (100, 300, 500) comprises locally removing material from the optical component (100, 300, 500) by means of the photon beam (630, 840, 1030). A device (700) as claimed in claim 3, wherein the local removal of material includes at least one of the following groups: removing excess material from at least one element of an absorber pattern (140) of a lithography mask (100), removing material from the multi-layer structure (120) of the optical component (300), and removing at least one particle (550) from the optical component (500). A device (700) as claimed in claim 1, wherein the at least one light source (610, 1010, 1020) is further designed to set the energy density of the photon beam (605, 1030, 1130) for repairing the at least one defect (150, 350, 550, 1450) of the optical component (100, 300, 500). A device (700) as claimed in claim 1, further comprising an energy sensor (690) for detecting photons reflected from the optical component (100, 300, 500) and/or from the at least one defect (150, 350, 550, 1450) during a repair period for the purpose of monitoring the repair. A device (700) as claimed in claim 6, wherein the device (700) is configured to operate the at least one light source (610, 1010, 1020) and the energy sensor (690) in a closed feedback loop. The device (700) of claim 1 further comprises at least one first reflector (620) for scanning the photon beam (630) over the at least one defect (150, 350, 550, 1450) of the optical component (100, 300, 500); and at least one second reflector (660) for guiding the photon beam (760) to the area of the optical component (100, 300, 500) containing the at least one defect (150, 350, 500, 1450). The device (700) of claim 1 further comprises a control device (750) configured to move the at least one first reflector (620) and/or the at least one second reflector (660) beyond a visual distance. A device (700) as claimed in claim 1, wherein the device (700) comprises a Fresnel zone plate (850), and/or wherein the control device (750) is designed to move the Fresnel zone plate (850) into and out of the photon beam (830). A device (700) as claimed in claim 10, wherein the control device (750) is further designed to configure the device (700) for a test mode using the photon beam (760, 830, 1130), and/or wherein the control device (750) is further designed to switch the device (700) between the test mode and a repair mode. As in claim 1, the device (700) further comprises a sample clamp for fixing the optical component (100, 300, 500), the sample clamp being designed to rotate the optical component (100, 300, 500) around at least one axis, and/or the sample clamp being further designed to displace the optical component (100, 300, 500) in at least one lateral direction for the purpose of inspecting a substantially defect-free area of the optical component (100, 300, 500) using the photon beam (760, 830, 1130). A device (700) as claimed in claim 1, wherein the at least one light source (610, 1010, 1020) includes a first light source (1020) designed to scan a focused photon beam (1030) over the at least one defect (150, 350, 550, 1450) for the purpose of repairing the at least one defect (150, 350, 550, 1450), and includes a second light source (1010) designed to guide the photon beam (1130) to the area of the optical component (100, 300, 500) including at least the at least one defect (150, 350, 550, 1450). A device (700) as claimed in claim 1, wherein during the repair and/or during an inspection, the optical component includes a film (1310) through which the photon beam (630, 760, 830, 840, 1030, 1130) is radiated. A method (1800) for repairing at least one defect (150, 350, 550, 1450) of an optical component (100, 300, 500) within an extreme ultraviolet (EUV) wavelength range using a device as claimed in claim 1, wherein the optical component (100, 300, 500) comprises a substrate (110) and a multilayer structure (120) disposed on the substrate (110), the method comprising the following steps: a. generating a photon beam (605, 1030, 1130) within the EUV wavelength range and/or soft x-ray radiation within the wavelength range; and b. The photon beam (605, 1030, 1130) is configured so that the at least one defect (150, 350, 550, 1450) is repaired by locally modifying the optical component (100, 300, 500). A method (1800) as claimed in claim 15, wherein setting the photon beam (605, 1030, 1130) includes at least one of the following groups: focusing the photon beam (605, 1030, 1130), changing a pulse power of the photon beam (605, 1030, 1130), changing a polarization of the photon beam (605, 1030, 1130), and changing an incident angle of the photon beam (605, 1030, 1130) with respect to a normal direction of the optical component (100, 300, 500). The method (1800) of claim 15 further comprises the following step: switching between repairing the at least one defect (150, 350, 550, 1450) of the optical component (100, 300, 500) using the photon beam (630, 840, 1030) and inspecting the optical component (100, 300, 500) and/or the at least one defect (150, 350, 550, 1450) of the optical component (100, 300, 500) using the photon beam (760, 830, 1130). The method (1800) of claim 15 further comprises at least one of the following steps: a. Inspecting the at least one defect (150, 350, 550, 1450) with the photon beam (760, 830, 1130), and/or inspecting a substantially defect-free reference position with the photon beam (760, 830, 1130); b. Determining a repair form for the at least one detected defect (150, 350, 550, 1450) if the at least one detected defect (150, 350, 550, 1450) exceeds a predetermined threshold; c. Repairing the at least one defect (150, 350, 550, 1450) with the photon beam (630, 840, 1030); d. Inspecting a repaired position of the optical component (100, 300, 500) with the photon beam (760, 830, 1130); and e. If a remaining residue of the at least one defect (150, 350, 550, 1450) exceeds the predetermined threshold, repeating steps a. and b.. A computer program comprising instructions which, when executed by a computer system, cause the computer system to perform the method steps of claims 15 to 18.

Images