Apparatus and method for removing single particulate from substrate

Abstract

To provide an apparatus (300, 400) and a method (2000) for removing at least a single particulate (320) from a substrate (310, 402), especially an optical element for extreme ultraviolet (EUV) photolithography.SOLUTION: The apparatus (300, 400) comprises: (a) an analysis unit (330) designed to determine at least one constituent of a material composition of the at least one single particulate (320); and (b) at least one gas injection system (360) designed to provide a gas (370, 1470) matched to the particular constituent in an environment of the at least one single particulate (320); (c) where the matched gas (370, 1470) contributes to removing the at least one single particulate (320) from the substrate (310).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The German priority application, filed with the German Patent and Trademark Office on July 8, 2020, is incorporated by reference in its entirety into the present application.

[0002] The present invention relates to an apparatus and method for removing at least one single (micro)particle from a substrate, in particular from optical elements used in photolithography systems, for example systems in the extreme ultraviolet (EUV) wavelength range. [Background technology]

[0003] As a result of the steadily increasing integration density in microelectronics, photolithography masks are required to image increasingly smaller features into the photoresist layer of the wafer. This is equally true for templates used in nanoimprint lithography. To meet these requirements, exposure wavelengths are shifting to ever shorter wavelengths. Currently, argon fluoride (ArF) excimer lasers are primarily used for exposure, emitting at a wavelength of 193 nm. Intensive research is being conducted on light sources emitting in the EUV wavelength range (10 nm to 15 nm) and corresponding EUV masks. To increase the resolution of the wafer exposure process, several variants of the traditional binary photolithography mask have been developed simultaneously. Examples include phase masks or phase-shift masks and masks for multiple exposures.

[0004] Due to the ever-decreasing dimensions of structural elements, photolithography masks, photomasks, or simply masks, cannot always be fabricated without defects that are printable or visible on the wafer. Because fabricating photolithography masks is expensive, defective photomasks, like templates used in nanoimprint lithography, are repaired whenever possible.

[0005] Repairing a photomask involves removing portions of the absorber pattern that are present in mask locations not intended in the design. Additionally, absorbing material is deposited on the mask in locations where there is no absorbing material, despite the mask design providing absorbing pattern elements. Both types of repair processes can create chips, debris, or particles that can land on transparent or reflective locations on the photomask and can be visible as imaging aberrations on the wafer.

[0006] Of greater concern, however, are soil particles from the environment that deposit on the surface of the mask, or more generally, on the optical elements or components of a photolithography exposure system. These particles are typically removed from the surface of the mask during mask fabrication and / or cleaning steps during manipulation of the mask or optical elements. Figure 1 shows a top view of a portion of a photomask with particles that are located on the mask's pattern elements and can be removed by the cleaning process. Additionally, particles that may adhere to the mask can be generated by handling and / or manipulating the mask during the fabrication process.

[0007] Photolithography exposure systems operating with electromagnetic radiation in the EUV wavelength range present two additional challenges. EUV masks currently lack protection (e.g., a thin film) for the mask surface on which the structured elements are mounted. As a result, EUV masks are particularly susceptible to particle deposition on this structured surface. Second, EUV radiation sources typically use tin plasma to generate EUV radiation (e.g., Oscar O. Versolato: "Physics of laser-driven tin plasma sources of EUV radiation for nanolithography," Plasma Sources Sci. Technol. 28 (2019) 083001, doi: 10 / 1088 / 1361-6595 / ab302). Particles from the hot plasma can deposit on components of the EUV exposure system, particularly on optical components or elements of the system, including the EUV mask, potentially impairing their functionality.

[0008] The ever-decreasing structural dimensions of photolithography masks make cleaning processes more difficult (e.g., T. Shimomura and T. Liang: "50 nm particle removal from EUV mask blank using standard wet clean", Proc. of SPIE Vol. 7488, pp. 74882F-1 - 74882F-8). Furthermore, as a result of decreasing exposure wavelengths, smaller foreign or contaminant particles adsorbed on the surface of the mask or on the surfaces of optical elements of the exposure system are becoming visible during the wafer exposure process. Figure 2 shows a diagram of a portion of a photomask where two particles localized in the contact holes of the mask cannot be removed from the mask by the cleaning process.

[0009] Some references on the use of nanomanipulators or micromanipulators to study the movement of nanoparticles are listed below as examples: HH Pieper: "Morphology and electric potential of pristine and gold covered surfaces with fluorite structure", Thesis, TIFF2025131616000002.tif868S. Darwich et al.: "Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle - substrate chemistry and morphology, and operating conditions", Beilstein J. Nanotechnol., vol.2 (2011), p.85-98; H.H. Pieper et al.: "Morphology and nanostructure of CeO2(111) surfaces of single crystals and Si(111) supported ceria films", Phys. Chemistry Chemical Physics, vol.14, p.15361ff, 2013; E. Gallagher et al.: "EUVL mask repair: expanding options with nanomachining", BACUS, vol.3, no.3 (2013), p.1-8; M. Martin et al.: "Manipulation of Ag nanoparticles utilizing noncontact atomic force microscopy", Appl.Phys.Lett., vol.72, no.11, September 1998, p.1505-1507; P.J. Durston et al.: "Manipulation of passivated gold clusters on graphite with the scanning tunneling microscope", Appl.Phys.Lett., vol.72, no.2, January 1998, p.176-178; R.Requicha: "Nanomanipulation with the atomic force microscope", Nanotechnology Online, ISBN: 9783527628155; C. Baur et al.: "Nanoparticle manipulation by mechanical pushing: underlying phenomena and real-time monitoring", Nanotechnology 9 (1998), p.360-364; JD Beard et al.: "An atomic force microscope nanoscalpel for nanolithography and biological applications", Nanotechnology 20 (2009), 445302, p.1-10; U.S. Patent No. 6812460. The following publications report on the picking and placement of particles on a substrate: J. Xu et al.: "Lifting and sorting of charged Au nanoparticles by electrostatic forces in atomic force microscopy", Small 2010, vol. 6, no. 19, pp. 2105-2108; N. Cao et al.: "Interactive micromanipulation of picking and placement of nonconductive microspheres in scanning electron microscope", Micromachines 2017, 8, 257, doi: 10.3390 / mi8080257; C. Baur and R. Stallcup: "Systems and methods for picking and placing of nanoscale objects utilizing differences in chemical and physical binding forces", Micromachines 8, p.257 (2017); U.S. Patent No. 8,696,818; Japanese Patent Publication No. 2005-084582; and U.S. Patent No. 6,987,277.

[0010] Particle transfer, especially lifting individual particles from a surface, is typically a complex and time-consuming process. Furthermore, particles that adhere to the surface of an optical element can be difficult to completely remove from the optical element. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] U.S. Patent No. 6,812,460 [Patent Document 2] U.S. Patent No. 8,696,818 [Patent Document 3] Patent Publication No. 2005-084582 [Patent Document 4] U.S. Patent No. 6,987,277 [Non-patent literature]

[0012] [Non-Patent Document 1] Oscar O. Versolato: "Physics of laser-driven tin plasma sources of EUV radiation for nanolithography", Plasma Sources Sci. Technol. 28 (2019) 083001, doi: 10 / 1088 / 1361-6595 / ab302 [Non-patent document 2] T. Shimomura and T. Liang: "50 nm particle removal from EUV mask blank using standard wet clean", Proc. of SPIE Vol.7488, p.74882F-1 - 74882F-8 [Non-patent document 3] H.H. Pieper: "Morphology and electric potential of pristine and gold covered surfaces with fluorite structure", Thesis, University of Osnabruck 2012 [Non-Patent Document 4] S. Darwich et al.: "Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle - substrate chemistry and morphology, and operating conditions", Beilstein J. Nanotechnol., vol.2 (2011), p.85-98 [Non-Patent Document 5] H.H. Pieper et al.: "Morphology and nanostructure of CeO2(111) surfaces of single crystals and Si(111) supported ceria films", Phys. Chemistry Chemical Physics, vol.14, p.15361ff, 2013 [Non-Patent Document 6] E. Gallagher et al.: "EUVL mask repair: expanding options with nanomachining", BACUS, vol.3, no.3 (2013), p.1-8 [Non-Patent Document 7] M. Martin et al.: "Manipulation of Ag nanoparticles utilizing noncontact atomic force microscopy", Appl.Phys.Lett., vol.72, no.11, September 1998, p.1505-1507

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Non-licensed literature 9

Non-licensed literature 10

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[0013] The problem addressed by the present invention is therefore to specify an apparatus and method that allows for improved particle removal from substrates, and in particular from optical elements for photolithography.

[0014] According to one exemplary embodiment of the present invention, this problem is solved by an apparatus according to claim 1 and a method according to claim 19. In one embodiment, an apparatus for removing at least one single particle from a substrate, in particular from an optical element for extreme ultraviolet (EUV) photolithography, comprises (a) an analysis unit designed to determine at least one constituent of a material composition of the at least one single particle, and (b) at least one gas injection system designed to supply a gas matched to the specific constituent in an environment of the at least one single particle, and (c) the matched gas contributes to removing the at least one single particle from the substrate.

[0015] A common reason why local etching processes are difficult to perform is that the material composition of the particles to be removed is generally unknown. Therefore, the local etching and / or deposition process can only be partially matched to the particles to be removed, or very often cannot be matched at all. Therefore, local etching processes are often time-consuming and quite often unsuccessful.

[0016] The material composition of the particles adsorbed on the surface is at least partially determined prior to the processing step, allowing the processing step, e.g., etching or deposition, to be tailored to the specific particles, allowing for near-residue-free removal of the particles without significantly damaging the substrate surrounding the particles during the processing step.

[0017] The analysis unit may utilize at least one member of the group consisting of the following techniques: Energy Dispersive X-ray Spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Secondary Ion Mass Spectroscopy (SIMS), Secondary Neutral Mass Spectroscopy (SNMS), Rutherford Backscattering Spectroscopy (RBS), and Low Energy Ion Scattering Spectroscopy (LEIS).

[0018] The analytical unit can be designed to take into account external inputs in determining at least one constituent of the material composition.

[0019] The external input may come from a technical expert using the apparatus of the present invention, or alternatively, may come from an external materials database, for example.

[0020] The analysis unit can also be designed to take into account the material composition of the substrate when determining the conditioning gas. The analysis unit can also be designed to determine an exposure dose of the conditioning gas to remove at least one single particle. The analysis unit can also be designed to take into account the substrate surrounding the particle to be removed when determining the exposure dose.

[0021] The device may include a materials database and / or have an interface that allows access to the materials database. The materials database may include data on the possible materials of at least one single particle.

[0022] The apparatus may also include a machine learning model trained to predict at least one constituent of the material composition of the at least one single particle using the measurement data from the analytical unit. Further, the apparatus may include a predictive filter designed to predict at least one constituent of the material composition of the at least one single particle using the measurement data from the analytical unit.

[0023] Based on the measurement data from the analytical unit, the ML model and / or predictive filter can predict one or more constituents of the material composition. This allows for the implementation of a nearly automated processing step specifically tailored to the identified particle. Additionally, the uncertainty regarding the determination of the particle's material composition can be estimated as well. In this way, it becomes possible to select the most suitable possible processing step for the particle.

[0024] The trained machine learning model may include a recurrent neural network (RNN), which may include a long short-term memory (LSTM) network.

[0025] The training data from the ML model may be measured data of the material composition of known particles that may occur in the photolithography optical element. In addition, the training data for the machine learning model may further include measured data of specific composite material compositions. Furthermore, the ML model may be trained using data collected by the repair tool operator during operation.

[0026] The predictive filter may include an element from the group of a Kalman filter, a particle filter, and a low-pass filter with a finite impulse response.

[0027] The apparatus may further comprise at least one microscope system designed to image the at least one single particle, preferably during removal of the at least one single particle.

[0028] The microscope system can be used to identify particles on a substrate, and can also be used to monitor and / or control particle processing steps.

[0029] The microscope system can be designed to determine parameters of at least one single particle.

[0030] The microscope system may use particles with zero mass to image at least one single particle. The microscope system may use photons in the extreme ultraviolet wavelength range to image at least one single particle. The microscope system may use particles with a non-zero mass to image at least one single particle. The microscope system may use charged particles, particularly electrons and / or ions, to image at least one single particle. The microscope system may use electrically uncharged particles with a non-zero mass, particularly atoms and / or molecules, to image at least one single microparticle.

[0031] The substrate may include a photolithography mask, a nanoimprint lithography template, and / or optical elements of a photolithography exposure tool. The photolithography mask may be any type of photomask, such as a binary mask or a phase-shift mask. More specifically, the photolithography mask may include a mask in the deep ultraviolet (DUV) or extreme ultraviolet (EUV) wavelength range.

[0032] The at least one single particle can have any desired shape. The at least one single particle can have a diameter in the range of about 1 nm to about 100 μm. The at least one single particle can interact with the substrate in any desired manner.

[0033] The apparatus may also include a control unit designed to monitor the gas composition of the conditioning gas. In addition, the control unit may be designed to control the gas flow rate of the conditioning gas. In this way, the control unit can monitor the supply of a specific exposure dose near the particles to be removed.

[0034] The harmonic gas is capable of spontaneously etching at least one single particle.

[0035] In one embodiment, the gas injection system supplies a gas matched to the identified particles that spontaneously etches the particles in the environment of the particles to be removed, i.e., without the further supply of external energy.

[0036] The matching gas is capable of spontaneously etching at least one single particle at a rate greater than the spontaneous etching rate of the substrate, such as at least 2 times (by a factor of 2:2), preferably at least 5 times (by a factor of 5:5), more preferably at least 10 times (by a factor of 10:10), and most preferably at least 30 times (by a factor of 30:30) the spontaneous etching rate of the substrate.

[0037] In the case of particle treatment processes carried out in the form of etching processes, it is advantageous for the etching process to attack the substrate surrounding the particles as little as possible, and therefore it is advantageous for the analysis unit to take into account the composition of the substrate in the environment of the particles to be removed when determining the conditioning gas.

[0038] The harmonic gases are ruthenium (Ru), tantalum nitride (TaN), silicon dioxide (SiO2) and Mo. x SiO y N z where 0≦x≦0.5, 0≦y≦2, 0≦z≦4 / 3, and the etching rate is at least 2 times (at least by a factor of 2:2), preferably at least 5 times (at least by a factor of 5:5), more preferably at least 10 times (at least by a factor of 10:10), and most preferably at least 30 times (at least by a factor of 30:30) less than the etching rate of at least one individual particle.

[0039] The at least one single particle may include silicon (Si), and the conditioning gas may include at least one halogen, particularly a halogen compound, such as xenon difluoride (XeF2). The at least one single particle may include one or more organic compounds, and the conditioning gas may include water vapor (H2O). The at least one single particle may include tin (Sn), and the conditioning gas may include at least hydrogen (H2), at least one hydrogen compound, and / or at least nitrosyl chloride (NOCl).

[0040] Etching gases of water vapor and / or nitrosyl chloride can be used to spontaneously etch particles having tin as the primary constituent.

[0041] The apparatus according to the present invention may further comprise at least one particle beam that initiates a local etching reaction of a first harmonic gas that etches the at least one single particle and / or initiates a local deposition reaction of a second harmonic gas that deposits material onto the at least one single particle.

[0042] In another embodiment, the particle beam in the apparatus may perform, for example, an electron beam-induced etching (EBIE) process and / or an electron beam-induced deposition (EBID) process.

[0043] The at least one single particle may include tin, and the at least one first harmonic gas may include at least one member from the group consisting of hydrogen compounds, hydrogen (H), halogen compounds, chlorine compounds, and nitrosyl chloride (NOCl).

[0044] The tin-containing particles can also be removed from the substrate by a particle beam-induced etching operation, where the etching gas selected is at least one member from the list above.

[0045] The particle beam of the microscope system can be the same as the particle beam of the instrument and the particle beam of the analysis unit. Alternatively, the microscope system, the instrument, and the analysis unit can each use their own particle beam. In addition, two of the three instruments or units can use one common particle beam.

[0046] The analyzer can be designed to determine a matching gas that deposits a localized protective layer on a substrate in an environment of the at least one single particle prior to processing the at least one single particle.

[0047] The gas injection system can also be designed to deposit a localized protective layer around at least one single particle.

[0048] The analysis unit can select a matching gas for depositing the localized protective layer from a group including metal carbonyls, transition element carbonyls, main group element carbonyls, metal alkoxides, transition element alkoxides, main group element alkoxides, and unsaturated aromatic hydrocarbons.

[0049] Metal carbonyls, transition element carbonyls, or main group element carbonyls include chromium hexacarbonyl (Cr(CO)6), molybdenum hexacarbonyl (Mo(CO)6), tungsten hexacarbonyl (W(CO)6), dicobalt octacarbonyl (Co2(CO)8), triruthenium dodecacarbonyl (Ru3(CO) 12 ), and iron pentacarbonyl (Fe(CO)5).

[0050] The metal alkoxides, transition element alkoxides, or main group element alkoxides can include tetraethyl orthosilicate (TEOS, Si(OC2H5)4) and titanium isopropoxide (Ti(OCH(CH)3)2)4).

[0051] The unsaturated aromatic hydrocarbon may include styrene.

[0052] The gas injection system can be designed to provide an intermittent gas flow rate of the harmonizing gas, thereby allowing the at least one particle beam to be used intermittently to process and image at least one single particle. The at least one particle beam can include at least one electron beam.

[0053] The at least one single particle may include molybdenum (Mo), and the matching gas may include xenon difluoride (XeF2). The at least one single particle may include silicon (Si) and / or ruthenium (Ru), and the matching gas may include XeF2 and water vapor (H2O). The at least one single particle may include one or more organic materials and water, and the matching gas may include XeF2.

[0054] The at least one single particle may include tin (Sn), and the harmonizing gas may include at least hydrogen (H) and / or at least one hydrogen compound. The at least one hydrogen compound may include at least one element from the group consisting of ammonia (NH), ammonium carbamate (HNCOONH), and ammonium carbonate ((NH)CO).

[0055] The hydrogen compounds can be used to remove tin particles from a substrate by a localized particle beam induced etching process.

[0056] The device may also include at least one micromanipulator unit designed to interact with at least one single particle.

[0057] As mentioned above, particles present on the substrate can be removed by a spontaneous or locally induced etching process. Alternatively, particles can be removed from the substrate by migration.

[0058] The microscope system can be designed to image at least one single particle while the particle is interacting with at least one micromanipulator unit, and the at least one micromanipulator unit can be designed to interact with the at least one single particle by at least one of van der Waals forces, electrostatic forces, and chemical bonding forces.

[0059] The advantage of the device described in this application is that it can image particles while they are being processed by the micromanipulator unit, which firstly makes difficult processing steps easier to perform and secondly largely prevents damage to the substrate by the micromanipulator unit during the processing steps.

[0060] The at least one micromanipulator unit may include at least one L-shaped micromanipulator or one tong-shaped micromanipulator.

[0061] The apparatus may further include a movement device designed to move the micromanipulator unit relative to the at least one single particle.

[0062] The at least one micromanipulator unit can be designed to perform at least one element from the group consisting of: moving at least one single particle on the substrate; crushing at least one single particle on the substrate; and picking up at least one single particle from the substrate.

[0063] The at least one micromanipulator unit may include at least two micromanipulators designed to fixate at least one single particle.

[0064] The at least one particle beam can be designed to induce charging of at least one single particle. The apparatus can further include an ion gun (flood gun) designed to induce charging of at least one single particle.

[0065] The movement device can be designed to position the at least one micromanipulator unit near the at least one single particle before removing and / or processing the at least one single particle, whereby the micromanipulator unit at least partially protects the substrate surrounding the at least one single particle from any effects of processing the at least one single particle.

[0066] By strategically positioning one or more micromanipulators of the micromanipulator unit near a single particle to be removed, it is possible to at least partially prevent the processing step from also affecting the substrate surrounding the particle. Proper positioning of the micromanipulator unit can, for example, prevent a localized protective layer from being deposited around the particle to be removed before the processing step is performed.

[0067] The at least one micromanipulator unit may include at least one micromanipulator, and the at least one micromanipulator unit may be designed to heat the at least one micromanipulator.

[0068] The micromanipulator unit can be designed to electrically heat the at least one micromanipulator, and the at least one particle beam can be designed to heat the at least one micromanipulator and / or the at least one single particle by depositing energy on the at least one micromanipulator of the micromanipulator unit and / or the at least one single particle.

[0069] At least one micromanipulator can be designed to include a metal or metal alloy that forms an alloy with at least one single molten particulate.

[0070] If the material composition of the particle to be removed has a low melting point and the micromanipulator of the micromanipulator unit has a material composition that can form an alloy with the material of the particle to be removed, the particle can be removed from the substrate by forming an alloy with the micromanipulator. Depending on the size and composition of the individual particle, the micromanipulator can capture multiple particles before exhausting its ability to capture the particle's material.

[0071] At least one micromanipulator may include bismuth (Bi), a bismuth alloy and / or a bismuth coating, and at least one constituent of the material composition of the at least one single particle may include tin (Sn).

[0072] Alloying the particles to be removed with the micromanipulator is another method for removing particles containing low melting point metals from a substrate.

[0073] The alloy of bismuth and tin may have a material composition ranging from 40% Bi, 60% Sn to 58% Bi, 42% Sn.

[0074] At least one micromanipulator may include a carbon structure that picks up at least one single heated particle. The carbon structure of the micromanipulator may include at least one carbon nanotube (CNT) or at least one multi-walled carbon nanotube (MWCNT). The carbon nanotube and / or multi-walled carbon nanotube may include a heated carbon nanotube and / or a heated multi-walled carbon nanotube that wets the at least one single particle. The at least one single particle may include tin. The fabrication and use of carbon nanotubes as measurement probes for scanning electron microscopes is described in the paper: ZW Xu et al.: "Carbon nanotube AFM probe technology", https: / / doi.org / 10.5772 / 17350.

[0075] Carbon nanotubes can be electrically soldered, and therefore have adhesive properties to metals, so that carbon nanotubes or heated carbon nanotubes can lift low-melting-point metal-containing particles, especially tin-containing particles, from the substrate surface by capillary force.

[0076] The apparatus may include a voltage source designed to generate a current flow between the at least one micromanipulator and the at least one single particle, the current flow causing electromigration in the at least one single particle.

[0077] The voltage source can be designed to adjust the polarity of the current, causing ions of the at least one single particle to move toward the at least one micromanipulator of the at least one micromanipulator unit. The at least one micromanipulator unit and / or the at least one particle beam can be designed to further heat the at least one single particle while the current is passing through the particle.

[0078] The apparatus may further include a sample stage designed to establish electrical contact with the substrate and also having an interface for connecting a voltage source.

[0079] The apparatus may also include a jetting system designed to coat at least one single particle with oil. The jetting system may be designed to coat at least one single particle with oil prior to processing of the particle.

[0080] Coating the particles with oil has two advantages: first, coating the particles with oil reduces the effect of atmospheric oxygen on the particles during the processing step, and second, the oil film on the particles to be processed facilitates the transfer of heat to the particles.

[0081] The at least one particle beam can be configured to initiate electrostatic charging of the at least one single particle prior to supplying the at least one single particle with the harmonic gas, where the harmonic gas deposits material on the particle.

[0082] The electrostatic charge of the particles to be treated allows individual material to be deposited on the particles to be treated. As material is deposited on the material to be removed, its surface area increases, making it easier to remove the particles from the substrate. In the simplest case, the enlarged particles can be removed from the substrate by a substrate cleaning process. Generally, the enlarged particles can be moved relatively easily across the surface of the substrate using one or more micromanipulators of the micromanipulator unit.

[0083] The analysis unit can select a harmonic gas with a higher deposition rate than on the substrate, such that the deposition rate on at least one single particle is 2 times, preferably 5 times, more preferably 10 times, and most preferably 30 times higher than on the substrate. Furthermore, it is advantageous to align the harmonic gas with the particle beam that induces the deposition process or its scanning.

[0084] The at least one single particle may include one member from the group consisting of particles that are unstable with respect to removal from the substrate, particles having two or more particulate fragments, and particles that include particulate agglomerates, and the gas injection system may be further configured to supply a conditioning gas in the environment of the at least one single particle that deposits material on the at least one single particle prior to removal.

[0085] If the particle to be removed from the substrate is unstable, consists of multiple particles, or consists of localized agglomerates of small particles, it is advantageous to stabilize the particle by depositing a material prior to the processing step so that the stabilized particle can be removed from the substrate as a whole.

[0086] The micromanipulator unit can be designed to remove a first portion of the at least one single particle, and the harmonic gas can contribute to removing a second portion of the at least one single particle by spontaneous etching and / or particle beam-induced etching.

[0087] When the particle is lifted from the substrate surface by the micromanipulator, it may leave behind residues that can be removed from the substrate in a second step by spontaneous or particle-beam-induced etching processes.

[0088] The gas injection system can also be designed to supply, after removal of the at least one single particle, a reconstruction gas in the environment of the removed at least one single particle that at least partially eliminates damage to the substrate caused during removal of the at least one single particle.

[0089] The reorganization gas may include at least one member from the group consisting of a metal carbonyl, for example chromium hexacarbonyl (Cr(CO)6), tetraethyl orthosilicate (TEOS, Si(OC2H5)4), and nitrogen dioxide (NO2).

[0090] The gas injection system can also be designed to supply a passivation gas in the environment of the at least one single removed particle after removing the at least one single particle, and the passivation gas prevents the substrate from being damaged by the harmonic gas still present when the processing step for the at least one single particle is completed.

[0091] The passivation gas may include at least one member from the group consisting of water vapor (H2O), nitrogen dioxide (NO2), nitric oxide (NO), oxygen (O2), nitrosyl chloride (NOCl), and TEOS.

[0092] The microscope system of the apparatus defined above can be used to inspect the substrate for damage resulting from the particle removal process. The analysis unit and gas injection system of the apparatus can be used to firstly minimize damage and secondly even virtually eliminate damage to the substrate caused by downstream repair or reorganization steps.

[0093] In one embodiment, a method for removing at least one single particle from a substrate, particularly from an optical element for extreme ultraviolet (EUV) photolithography, includes steps of: (a) determining at least one constituent of a material composition of the at least one single particle; (b) supplying a gas in an environment of the at least one single particle that is matched to the particular constituent of the material composition; and (c) the matching gas contributes to removing the at least one single particle from the substrate.

[0094] The method for removing at least one single particle may further include performing a particle beam-induced etching process using an etching gas to remove at least the first single particle before determining at least one constituent of the material composition of the at least second single particle. The etching gas may include xenon difluoride (XeF2). Additionally, the etching gas may include an additive gas, such as oxygen (O2).

[0095] The method according to the present invention can be implemented as a two-stage process. In a first process step, a first portion of particles present on the substrate is removed by performing a localized particle beam-induced etching process using a conventional EBIE process. In a second process step, the material composition of the remaining second portion of particles is at least partially determined using an analysis unit. The second portion of particles is then removed from the substrate by performing a spontaneous etching process and / or a particle beam-induced etching process using one or more harmonic gases.

[0096] The computer program may include instructions that, when executed by the computer program, cause an apparatus according to any of the above aspects to perform the method steps of the above method.

[0097] In the detailed description that follows, presently preferred embodiments of the invention are described with reference to the drawings. [Brief explanation of the drawings]

[0098] [Figure 1] FIG. 1 shows a top view detail of a photolithography mask with a single particle that can be removed by a cleaning process. [Figure 2] FIG. 10 shows a top view detail of a photolithography mask with two single particles that cannot be removed by the cleaning process. [Figure 3] FIG. 1 presents some components of an apparatus for removing single particles from a substrate. [Figure 4a]1 is a cross-sectional view of a schematic block diagram of some key components of an apparatus that can be used to treat or remove one or more particles from a substrate. [Figure 4b] 4b is a cross-sectional view of the device of FIG. 4a, with the cross-sectional plane rotated 90° relative to FIG. 4a. [Figure 5] FIG. 1 is a diagram of a first embodiment of a micromanipulator unit. [Figure 6] FIG. 10 is a diagram of a second embodiment of the micromanipulator unit. [Figure 7] FIG. 10 is a diagram of a third embodiment of the micromanipulator unit. [Figure 8] FIG. 1 presents a schematic portion of a first embodiment of removing particles by performing a spontaneous etching process using a harmonic gas. [Figure 9] FIG. 1 illustrates the placement or deposition of a localized protective layer around a particle to be removed. [Figure 10] FIG. 10 illustrates the removal of the deposited localized protective layer after removing particles from the substrate. [Figure 11] 1 is a schematic diagram showing a first embodiment of a protective part of a substrate, surrounding a particle to be removed by two micromanipulators; [Figure 12] 10 is a schematic diagram showing a second embodiment of a protective part of the substrate, surrounding a particle to be removed by two micromanipulators. FIG. [Figure 13] FIG. 10 illustrates a second example of particle removal by performing a spontaneous etching process with a harmonic gas. [Figure 14] FIG. 1 illustrates an example of an EBIE process using a harmonizing gas to remove particles from a substrate. [Figure 15] 10A-10C present an example of removing metal-containing particles by alloying using a micromanipulator. [Figure 16] FIG. 10 illustrates stabilizing unstable particles by depositing material onto them so that the stabilized particles can be picked up en masse from the substrate by a micromanipulator. [Figure 17] FIG. 10 shows a micromanipulator approaching a particle that is bonded to a substrate by a particle base. [Figure 18] FIG. 10 shows a particle being picked up from a substrate, with the base of the particle remaining on the substrate as particle residue. [Figure 19] FIG. 10 illustrates the removal of particle residues by performing an EBIE process with harmonizing gas. [Figure 20] 1 is a flow diagram of a method for removing at least one single particle on a substrate, particularly on an optical element for the EUV wavelength range. DETAILED DESCRIPTION OF THE INVENTION

[0099] The following provides a detailed description of currently preferred embodiments of the apparatus and method of the present invention for removing at least one single particle on a substrate. The apparatus and method of the present invention are described below using the example of a photomask for the extreme ultraviolet (EUV) wavelength range. However, these apparatus and methods are not limited to the examples described below. Instead, these apparatus and methods can be used to treat or remove particles from any type of photomask. Furthermore, the described apparatus and corresponding methods can be used to treat particles present on components of a photolithography exposure tool, particularly on optical components whose optical properties are impaired by the presence of particles. Furthermore, as will be readily apparent to those skilled in the art, the apparatus and method of the present invention can similarly be utilized to remove particles from templates used in different modes of nanoscale imprint lithography.

[0100] 1 shows a top view of a detail of a photolithography mask 100. The detail of the photolithography mask 100 presents a substrate 110 on which three pattern elements 120, 130, 140 made of absorber material in the form of vertical strips are disposed. By identifying the location of a particle 150 on one of the pattern elements, namely on pattern element 130, the particle 150 can be removed from the photomask 100 by a cleaning process. Typically, the pattern elements 120, 130, 140 have a height of 50 nm to 200 nm.

[0101] FIG. 2 also depicts a detailed top view of a photolithography mask 200. The illustrated mask 200 includes a substrate 110. Two rows of six contact holes 220 have been introduced into the substrate 110 of the mask 200. A single particle 250 is located substantially at the center of the middle contact hole 220 in the upper row. In the lower row, a single particle 260 is located at the upper edge of the middle contact hole 220. Typically, the contact holes 220 have a depth in the range of 50 nm to 200 nm. Neither the particles 250 nor the particles 260 can be removed from the mask 200 by a cleaning process. In addition to the particles 250 and 260 present in the recesses of the photomask 200, even single particles adsorbed to the edges of the pattern elements 120, 130, and 140, and especially to the corners of the pattern elements, can be removed from the masks 100 and 200 by a cleaning process only with great difficulty, if at all. The following description of removing single particles 250, 260 from the photomask pertains to particles 250, 260 that cannot be removed from the photomask 200 by a cleaning process.

[0102] 3 shows a diagram of some components of an apparatus 300 that allows for the treatment and / or removal of one or more particles 320 from a substrate 310. The substrate 310 may include the substrate 110 of a photomask 100, 200. The substrate 310 may include the substrate 110 of any type of photomask 100, 200. More specifically, the substrate 310 may include an EUV mask. However, the substrate 310 may also include optical components of a mask exposure system, particularly an exposure system for the EUV wavelength range.

[0103] The substrate 310 can be placed on a sample stage 325. As indicated by the curved arrow 305 in FIG. 3, the sample stage 325 can be rotated around one, two, or three axes. This allows for processing of the particles 320 at various angles. In addition, the sample stage 325 can move, for example, in two directions within the plane of the sample stage 325, and in three spatial directions, i.e., perpendicular to the plane of the sample stage 325 (not shown in FIG. 3). The sample stage 325 can have electrical terminals, by which a potential can be applied to the substrate 310 or to the particles 320 (not shown in FIG. 3).

[0104] In FIG. 3 , the illustrative particles 320 have a spherical shape. However, the particles 320 to be removed from the substrate 310 do not have to be spherical. Instead, the particles 320 can be any shape. The particles 320 can have diameters ranging from about 1 nm to about 100 μm. Additionally, the particles 320 can interact with the substrate 310 in any manner. For example, the particles 320 can adhere to the particles 320 and / or the substrate 310 by van der Waals forces, or by chemical bonds or electrostatic charges on the particles.

[0105] The particles 320 may include pure metals and / or metal alloys. The particles 320 may include oxides, halides, nitrides, sulfides, phosphides, salts, or organic compounds. The organic compounds may include carbon compounds, hydrocarbon compounds, and photoresists.

[0106] The apparatus 300 may include an analysis unit 330. The analysis unit 330 may include a particle beam source 335 capable of generating a particle beam 350, which may be directed onto the particle 320 in the form of a focused particle beam 350. The particle beam 350 may include a photon beam in the visible, ultraviolet (UV), deep ultraviolet (DUV), and / or extreme ultraviolet (EUV) wavelength range. The particle beam 350 may include an electron beam, an ion beam, an atomic beam, and / or a molecular beam. The particle beam source 335 may further include a scanning device (not shown in FIG. 3 ) capable of scanning the particle beam 350 across the particle 320. The analysis unit 330 may include a detector 340 capable of detecting particles 345 arising from the particle 320. The particle 345 or particle beam 345 may include microparticles ejected from the particle 320 by the beam 350 incident on the particle 320. Detector 340 analyzes particle 345 or particle beam 345 and, based on this analysis, determines the most significant constituent of particle 320. The most significant constituent of particle 320 is typically the constituent of the material composition of the particle that has the greatest percentage of that material composition.

[0107] The analysis unit 330 may for example be implemented in the form of an energy dispersive X-ray spectroscopy unit and / or a secondary ion mass spectroscopy unit.

[0108] Particles 345 or particle beam 345 may alternatively comprise particles of incident particle beam 350 that are reflected by particle 320 or by substrate 310 surrounding particle 320. If particle beam 345 predominantly comprises reflected particles of particle beam 350, particle beam source 335 and detector 355 form a microscope system 390 that can be used to image particles 320. Thus, analysis unit 330 may be combinable with microscope system 390. Alternatively, apparatus 300 may have a stand-alone analysis unit 330 and a stand-alone microscope system 390, in each case.

[0109] Additionally, the apparatus 300 includes a gas injection system 360 capable of supplying a conditioning gas 370 in the environment of the particles 320. The gas injection system 360 can be connected to a control unit 380 via a connection 385. The control unit 380 can first monitor the gas composition of the conditioning gas 370 and second control the gas flow rate of the conditioning gas 370 under open-loop or closed-loop control. Additionally, the control unit 380 can include a connection to an analysis unit 330, which is omitted from FIG. 3 for clarity. Through this connection, the control unit receives information about the composition of the particles 320 and the conditioning gas 370. Additionally, the gas injection system 360 can also supply a reorganization gas and / or gases for depositing a protective layer around and / or on the particles 320 to be removed.

[0110] Finally, the apparatus 300 includes a micromanipulator unit 395 designed to handle the particles 320. The micromanipulator unit 395 is described in detail in the context of Figures 5-7.

[0111] Figure 4a shows a cross-sectional view of essential components of an apparatus 400 that can be used to process one or more particles 320 from a substrate 310, for example from a photolithography mask 100, 200. Figures 4a and 4b should be viewed as interrelated. Figure 4b presents a cross-section of essential components of apparatus 400 from Figure 4a, with the cross-sectional plane rotated 90° relative to Figure 4a. Figures 4a and 4b show an embodiment of apparatus 300 of Figure 3 in more detail.

[0112] 3, the substrate 402 can be any optical component of a photolithography exposure system, any photomask 100, 200, or a template for a nanoimprint technique. However, similar to the processing of photomasks, the apparatus 400 can also be used to process integrated circuits, microelectromechanical systems (MEMS) and / or integrated optical circuits that have excess material, for example in the form of particles 320, in locations that are difficult to access.

[0113] The illustrative apparatus 400 of Figure 4 is a modified scanning electron microscope (SEM) 401 equipped with two micromanipulator units 465 and 475 in the form of atomic force microscopes (AFMs). An electron gun 406 generates an electron beam 409 which is directed by elements 408 and 412 as a focused electron beam 410 onto a substrate 402 placed on a sample stage 404 in the form of a three-point support mechanism 403.

[0114] The sample stage 404 has an adjustment device (not shown in FIG. 4 ) by which the position on the substrate 402 at which the particle 320 (not shown in FIG. 4 ) is located can be moved below the point of incidence of the electron beam 410 on the substrate 402 and / or into the processing region of the AFMs 465 and 475. In addition, the sample stage 404 can be moved in height, i.e., in the z-direction or beam direction of the electron beam 409, so that the focal point 410 of the electron beam rests on the surface of the substrate 404 (also not shown in FIG. 4 ). Furthermore, the sample stage 404 can be equipped with a device for setting and controlling the temperature (also not shown in FIG. 4 ), which makes it possible to bring the substrate 402 to a given temperature and to keep the substrate at that temperature.

[0115] The apparatus 400 of FIG. 4 uses an electron beam 409 as an energy source to induce a local chemical reaction in the harmonic gas 370. According to this embodiment, the harmonic gas 370 can perform a local etching reaction or a local deposition reaction. The electron beam 410 can be focused to a small focal spot with a diameter of <1 nm. In addition, the electrons incident on the surface of the substrate 402 hardly cause any damage to the substrate surface, even if their kinetic energy varies over a large energy range.

[0116] However, the apparatus 400 and method presented herein are not limited to using the electron beam 409. Instead, any desired particle beam capable of inducing a local chemical reaction in the harmonic gas 370 at the particle beam incidence point on the surface of the substrate 402 can be used. Examples of alternative particle beams include ion beams, atomic beams, molecular beams, and / or photon beams. Furthermore, two or more particle beams can be used in parallel. In particular, the electron beam 409 and the photon beam can be used simultaneously as energy sources (not shown in FIG. 4 ). This means that the apparatus 400 can use the electron beam 409 as part of the analysis unit 330 and the photon beam as part of the microscope system 390.

[0117] The electron beam 409, and optionally the photon beam, may be used to record an image of the substrate 402, in particular of areas of the substrate 402 that contain excess material in the form of one or more particles 320. The electron beam 409 can thus be used to locate, image, and analyze the particles 320. A detector 414 for detecting backscattered electrons and / or secondary electrons provides a signal corresponding to the surface contour of the particles 320 and / or corresponding to the composition of the substrate 402 or particles 320.

[0118] By scanning or rastering the focused electron beam 410 across the substrate 402 using a control unit 418, a computer system 420 of the apparatus 400 can generate an image of the substrate 402 or particles 320. The control unit 418 can be part of the computer system 420, as shown in Figure 4, or can be implemented as a separate unit (not shown in Figure 4). The computer system 420 can include algorithms implemented as hardware, software, firmware, or a combination thereof that enable an image to be extracted from the measurement data of the detector 414.

[0119] Additionally, computer system 420 may include algorithms that use measurement data from detector 414 to determine fundamental constituents of the material composition of particles 320. Furthermore, computer system 420 may include machine learning models and / or predictive filters designed to predict at least one fundamental constituent of the material composition of particles 320 using measurement data from detector 414.

[0120] A screen 419 of the computer system 420 can display a calculated image and / or material composition of the particle 320. Furthermore, the computer system 420 can store measurement data from the detector 414, the calculated image and / or the composition of the particle 320. In addition, a control unit 418 of the computer system 420 can control the electron gun 406, the beam imaging element 408, and the beam forming element 412. Control signals from the control unit 418 can further control the movement of the sample stage 404 under open-loop or closed-loop control using an adjustment device (not shown in FIG. 4). Additionally, the control unit 418 can move the micromanipulator units 470 and 480, particularly relative to the particle 320.

[0121] The electron beam 410 incident on the substrate 402 can electrostatically charge the particles 320 and / or the substrate 402 surrounding the particles 320. Electrostatic charging of the particles 320 may be desirable to facilitate interaction of the particles 320 with one or both of the micromanipulator units 470, 480. To electrostatically charge the particles 320 in a controlled manner, an ion gun (flood gun) 416 can be used to bombard the surface of the particles 320 and / or the substrate 402 with ions of low kinetic energy. By way of example, argon ions with kinetic energies of several hundred eV can be used for this purpose.

[0122] 4a and 4b includes eight reservoir vessels for eight different process or precursor gases for processing particles 320 on a substrate 402 disposed on a sample stage 404. A first reservoir vessel 425 stores a first etching gas, such as xenon difluoride (XeF) and / or nitrosyl chloride (NOCl). The etching gas can be used to remove one or more particles 320 from the substrate 402 in a non-matched local etching operation.

[0123] The second reservoir vessel 430 stores a first deposition gas. The first deposition gas may include, for example, a carbon-containing deposition gas, such as a metal carbonyl, for example, tungsten hexacarbonyl (W(CO)). The first deposition gas is preferably utilized to deposit a localized protective layer on the substrate 402 around the particles 320 to be removed.

[0124] The third reservoir vessel 435 stores a second deposition gas. The second deposition gas may include a metal carbonyl, for example, chromium hexacarbonyl (Cr(CO)). The second deposition gas is typically used to stabilize brittle particles 320 by depositing material onto the particles 320. Additionally, the second deposition gas can be used to increase the surface area of ​​the particles 320 by depositing additional material onto the particles, thus making the larger particles easier to remove from the substrate 402.

[0125] The fourth reservoir vessel 440 stores the organic compound together with a first harmonic gas, such as hydrogen (H) or water vapor (H0), which is selected to spontaneously etch the particles 320 to be removed without significantly damaging the substrate 402 surrounding the particles 320 or any deposited localized protective layers.

[0126] The fifth reservoir vessel 445 stores a second harmonizing gas, which may include, for example, ammonia (NH), ammonium carbamate (HNCOONH), and / or ammonium carbonate ((NH)CO).

[0127] The sixth reservoir vessel 450 stores a passivation gas. The passivation gas may include a metal carbonyl and / or TEOS. The passivation gas may be added to the first and / or second matching gas 370 to minimize damage to the substrate 402 surrounding the particles 320.

[0128] The seventh reservoir vessel 455 stores a reorganization gas, which may include at least one element from the group consisting of nitrogen oxides (NO, NO), water vapor (HO), oxygen (O), chromium hexacarbonyl (Cr(CO)), and TEOS gases. The reorganization gas allows for post-processing of the substrate 402 in the region of the particles 320 to eliminate damage to the substrate 402 caused during particle removal.

[0129] Finally, the eighth reservoir vessel 460 stores an additive gas. The additive gas can include an additional oxidant, such as a member from the group consisting of oxygen (O), ozone (O), water (H), heavy water (D), hydrogen peroxide (H), nitrous oxide (N), nitric oxide (NO), nitrogen dioxide (NO), nitric acid (HNO), and other oxygen-containing compounds. In a second embodiment, the additive gas includes a gas with reducing properties, such as hydrogen (H) or ammonia (NH).

[0130] An additive gas in the form of an oxidizing agent or a reducing agent can be utilized to improve selectivity, for example, when performing a localized etching process using the first and / or second matching gases to remove particles 320.

[0131] 4a and 4b, each reservoir vessel 425, 430, 435, 440, 445, 450, 455, 460 has its own control valve 426, 431, 436, 441, 446, 451, 456, 461 to monitor or control the level at which the corresponding gas is supplied per unit time, i.e., the gas flow rate at the point of incidence of the electron beam 410 and / or the location of the particle 320. The control valves 426, 431, 436, 441, 446, 451, 456, 461 are controlled and managed by the control unit 418 of the computer system 420. Thus, it is possible to adjust the partial pressure ratio of the gases supplied at the processing site over a wide range.

[0132] Additionally, in the illustrative apparatus 400, each reservoir vessel 425, 430, 435, 440, 445, 450, 455, 460 has its own gas injection system 427, 432, 437, 442, 447, 452, 457, 462, which terminates in a nozzle near the particle 320. In an alternative embodiment (not shown in FIG. 4), a gas injection system in the form of a mixing tube is used to deliver two or more, or all, of the process gases to the surface of the particle 320 as a common flow.

[0133] In the example illustrated in Figure 4, valves 426, 431, 436, 441, 446, 451, 456, 461 are located near the corresponding vessels 425, 430, 435, 440, 445, 450, 455, 460. In an alternative arrangement, the control valves can be incorporated near the corresponding nozzles (not shown in Figure 4). In contrast to the illustration shown in Figure 4, and in a currently not preferred manner, it is also possible to supply one or more of the gases stored in vessels 425, 430, 435, 440, 445, 450, 455, 460 to the lower part of vacuum chamber 485 of apparatus 400 in a non-directive manner. In this case, apparatus 400 would need to incorporate a stopcock (not shown in Figure 4) between the lower reaction space and the top of device 400 that supplies electron beam 409 to prevent an excessively low vacuum at the top of apparatus 400.

[0134] Each of the reservoir vessels 425, 430, 435, 440, 445, 450, 455, 460 can have its own temperature setting and control elements, which allow for both cooling and heating of the corresponding reservoir vessel, thereby allowing for the storage and delivery of deposition, etching, conditioning, reorganization, and / or additive gases, respectively, at their optimum temperatures (not shown in FIG. 4). Additionally, each delivery system 427, 432, 437, 442, 447, 452, 457, 462 can have its own temperature setting and temperature control elements (also not shown in FIG. 4) to deliver all process gases to the point of incidence of the particle 320 at their optimum process temperatures. The control unit 418 of the computer system 420 can control the temperature setting and temperature control elements of both the reservoir vessels 425, 430, 435, 440, 445, 450, 455, 460 and the gas injection systems 427, 432, 437, 442, 447, 452, 457, 462. The reservoir vessels 425, 430, 435, 440, 445, 450, 455, 460 can be embodied in the form of gas cylinders. The control valves 426, 431, 436, 441, 446, 451, 456, 461 can be embodied as flow regulators.

[0135] 4 includes a pump system 422 for generating and maintaining the required vacuum in a vacuum chamber 485. When control valves 426, 431, 436, 441, 446, 451, 456, and 461 are closed, a pressure of ≦10 -7 A residual gas pressure of mbar is obtained in the vacuum chamber 485 of the apparatus 400. The pumping system 422 may comprise separate pumping systems for the upper part of the apparatus 400, which supplies the electron beam 409, and for the lower part 495, which includes the sample stage 404 together with the substrate 402.

[0136] Finally, the illustrative apparatus 400 includes two scanning probe microscopes 465 and 475 in the form of atomic force microscopes (AFMs). The measurement heads 467 and 477 of the AFMs 465 and 475 can be adapted to micromanipulator units 470 and 480. The measurement heads 467 and 477 of the AFMs 465 and 475 can move the micromanipulator units 470 and 480 in at least two, preferably three, spatial directions and can therefore function as the movement devices 467 and 477 of the micromanipulator units. The AFMs 465 and 475 are controlled by a control unit 418 of a computer system 420. To implement the method of the present invention, the apparatus 400 does not need to include two scanning probe microscopes 465 and 475. One scanning probe microscope 465 or 475 equipped with a micromanipulator unit 470 or 480 is sufficient to process and / or remove particles 320 (not shown in FIG. 4 ) from the substrate 402.

[0137] 5 shows an example of a micromanipulator unit 510. The left portion of the image represents a side view of the manipulator unit 510, and the right portion of the image represents a top view thereof. The micromanipulator unit 510 includes a mounting portion 530 that allows the micromanipulator unit 510 to be incorporated into a measurement head 447, 467 of a scanning probe microscope 465, 475. The micromanipulator unit 510 may include a metal, a metal compound, a semiconductor material, and / or a compound semiconductor.

[0138] Additionally, the micromanipulator unit 510 includes a micromanipulator unit 520, which in the example shown in Figure 5 has a wide, flat shape. The width of the micromanipulator 520 may range from 1 nm to 100 µm, particularly from 10 nm to 100 nm. The thickness of the micromanipulator 520 may range from 5 nm to 10 µm. A currently preferred thickness is in the range of 5 nm to 500 nm.

[0139] The schematic diagram 600 in Figure 6 presents a second embodiment of the micromanipulator units 470, 480. Similar to Figure 5, the left portion of the image shows a side view of an L-shaped micromanipulator unit 610, while the right portion of the image represents its top view. The L-shaped micromanipulator includes an angled mounting portion 630 and a dipper-shaped micromanipulator 620. The mounting portion 630 typically has a length in the range of 100 nm to 10 mm, particularly in the range of 100 nm to 10 μm. The width of the dipper-shaped micromanipulator 620 encompasses dimensions between 10 nm and 10 mm, preferably between 10 nm and 10 μm. The thickness of the micromanipulator 620 ranges from 5 nm to 10 μm, particularly in the range of 5 nm to 500 nm.

[0140] The schematic diagram 700 of Figure 7 shows a modification of the L-shaped micromanipulator unit 610 of Figure 6. In addition to the micromanipulator 620, the ladle of the micromanipulator 720 has a notch or recess 750. The notch 750 may have dimensions in the range of 5 nm to 8 mm, particularly in the range of 5 nm to 5 μm. The notch 750 facilitates the picking up of the particle 320 from the substrate 310 by the micromanipulator 720.

[0141] The micromanipulators 520, 620, 720 can be electrically conductive or electrically insulating. The micromanipulators 520, 620, 720 can move the particles 320 on the substrate 402, for example, onto the pattern elements 120, 130, 140 of the photomask 100, 200, so that the particles 320 can be removed from the substrate 402, for example, from the photomask 100, 200, by a cleaning process. In addition, the micromanipulators 520, 620, 720 can crush the particles 320 or pick them up from the substrate 402. The micromanipulators 520, 620, 720 can interact with the particles through van der Waals forces, through electrostatic charges on the particles 320 and / or the micromanipulators 520, 620, 720, and / or through chemical bonds.

[0142] FIG. 8 illustrates a first example of removing particles 320 from a substrate 310. The substrate 310 may include the substrate 402 of the apparatus 400 of FIGS. 4a and 4b. The upper part of the image 800 illustrates the analysis of the identified particles 320 by the analysis unit 330, which has already been described in connection with the illustration of FIG. 3. For this purpose, the analysis unit 330 irradiates the particles 320 with a particle beam 350, for example, an electron beam 350. Secondary electrons 345 reflected by the particles 320 are detected by a detector 340 of the analysis unit 330. The analysis unit 330 uses the energy spectrum of the secondary electrons 345 to identify at least the basic composition of the particles 320. As already mentioned above, the analysis unit 330 may use correspondingly trained machine learning models and / or predictive filters for this purpose. Alternatively, the analysis unit 330 can scan the particle 320 and / or the substrate 310 with an ion beam, and the detector 340 can analyze particulates emitted from the particle.

[0143] The analysis unit 330 uses the confirmed composition to determine a matching gas 370 that will spontaneously etch the particles 320. If the basic constituent of the particles 320 includes silicon, xenon difluoride (XeF2) can be used as the matching gas 370. If the particles 320 have tin (Sn) as their primary constituent, hydrogen (H2) or nitrosyl chloride (NOCl) can be used as the matching gas 370.

[0144] During the analysis step, the analysis unit 330 can similarly ascertain the composition of the substrate 310 surrounding the particles 320 by scanning with the particle beam 350. When determining the matching gas 370, the analysis unit 330 can take into account the material composition of the substrate 310 so that a subsequent etching step on the particles 320 will only minimally damage the surrounding substrate 310. However, the composition of the substrate 310 may already be known to the analysis unit 330, for example by accessing a materials database.

[0145] If the analysis unit 330 cannot find a matching gas 370 that spontaneously etches the particles 320 without significantly damaging the substrate 310, the analysis unit 330 can prescribe depositing a localized protective layer around the particles 320 on the substrate 310 before starting the etching process on the particles 320. This operation is illustrated diagrammatically in FIG. 9. For this purpose, the electron beam 350 of the analysis unit 330 performs an EBID (electron beam induced deposition) process. The deposition gas 970 required for that purpose is preferably a metal carbonyl and is stored in the second reservoir vessel 430.

[0146] The size and thickness of the deposited localized protective layer 950 depend on the size and chemical composition of the particles 320 to be removed. For large particles 320, ranging in size up to the 100 μm region, the localized protective layer 950 can reach diameters approaching the millimeter range. The thickness of the protective layer 950 to be deposited is guided by the material composition of the particles 320 and, therefore, by the spontaneous etching time that the protective layer 950 must be able to withstand. The thickness of the protective layer 950 is typically in the range of 5 nm to 1 μm.

[0147] In the second step of the spontaneous etching process illustrated in FIG. 8 (schematically shown at the bottom of image 850), gas injection system 360 supplies a specific harmonic gas 370 to the location of particle 320, which spontaneously etches particle 320 to be removed. The spontaneous etching process of particle 320 can be observed by microscope system 390 of apparatus 300, 400. Microscope system 390 can use particle beam 350 in the form of a photon beam to image the particle etching process. Alternatively, the etching process can be imaged using analysis unit 330 (not shown in FIG. 8). In addition, microscope system 390 or analysis unit 330 can be used to observe the spontaneous particle etching process. Based on data from microscope system 390 and / or analysis unit 330, control unit 380 (not shown in FIG. 8) can control the gas flow rate of harmonic gas 370 under open-loop or closed-loop control. More specifically, the gas flow rate of the harmonic gas 370 can be stopped after the etching process is completed, thereby preventing the harmonic gas 370 from damaging the substrate 310 more than necessary.

[0148] If the substrate 310 has a localized protective layer 950 as depicted schematically in FIG. 9, this protective layer is again removed from the substrate 310 in a second etching step after removal of the particles 320. This process is shown schematically in FIG. 10 in the form of an EBIE (Electron Beam Induced Etching) process. The etching gas 1050 used for this purpose can be, for example, xenon difluoride (XeF) etching gas stored in the first reservoir vessel 425. The etching process on the protective layer 950 can be stopped at periodic time intervals to check the etching progress using the analysis unit 330 and / or the microscope system 390.

[0149] In an alternative embodiment, the protective layer 950 can be removed from the substrate 310 in a spontaneous etching process (not shown in FIG. 10). Spontaneous etching of a deposited protective layer based on a metal carbonyl deposition gas 970 can be performed using water (HO), oxygen (O), nitric oxide (NO), nitrogen dioxide (NO), xenon difluoride (XeF), nitrosyl chloride (NOCl), or a combination of these gases.

[0150] As an alternative to, or in addition to, applying the protective layer 950, one or more micromanipulators may be positioned near the particles 320 to be removed to protect the substrate 310 from the action of the harmonizing gas 370 during the particle etching process. FIG. 11 shows a schematic diagram of a first embodiment. Two micromanipulators 1120 are positioned near the particles 320 to be removed. The mountings of the micromanipulators 1120 are connected to measurement heads 447, 467 of scanning probe microscopes 465, 475. The measurement heads 447, 467 can be moved by the micromanipulators and must thus be positioned near the particles 320.

[0151] The micromanipulator 1120 can be a modification of the flat-board micromanipulator 520 depicted in FIG. 5. The modification of the micromanipulator 520 is the narrow section at the opposite end of the mounting portion 530. The tip 1140 of the micromanipulator 1120 allows optimal access of the micromanipulator 1120 toward the particle 320 to be removed. In the example presented in FIG. 11, two micromanipulators 1120 face each other. This arrangement of the micromanipulators 1120 is preferred to avoid damaging the substrate 310 in most directions. However, it is also possible to position two additional micromanipulators 1120 (not shown in FIG. 11) rotated 90° around the particle 320 relative to the configuration depicted in FIG. 11. It is, of course, also possible to use only one micromanipulator 1120 to protect the substrate 310, if necessary (also not shown in FIG. 11).

[0152] Figure 12 shows a second embodiment for protecting the substrate 310 during the particle etching process. In the example shown in Figure 12, two dipper-shaped micromanipulators 620 of the micromanipulator type 620 shown in Figure 6 are used to protect the substrate 310. As mentioned above in the context of Figure 11, it is of course possible to use a single micromanipulator 620 or four micromanipulators 620, preferably arranged at right angles to one another. It is also possible to use the micromanipulator 720 of the second embodiment shown in Figure 12 instead of the micromanipulator 620.

[0153] Protecting the substrate 310 with one or more micromanipulators 620, 1120 is more flexible than depositing a protective layer 950. Additionally, this method of substrate protection avoids performing deposition and etching steps for depositing and removing the protective layer 950.

[0154] Figure 13 presents a modified version of the spontaneous etching process for removing particles 320 illustrated in Figure 8. The upper portion of image 1300, similar to that portion of image 800 in Figure 8, depicts analyzing the material composition of identified particles 320. In addition to analyzing the chemical composition of particles 320, it is possible to determine the size of particles 320 using analysis unit 330 and / or microscope system 390.

[0155] The etching rate of a separately tuned gas 370 for particles 320 of a particular material composition can be measured in a separate process and recorded in a database. Based on the determined composition and ascertained parameters for the identified particles 320, it is possible to calculate the required duration of action or exposure to be given to the tuned gas 370. In this case, the spontaneous etching process on particles 320 caused by the tuned gas 370 can be performed without observation by the analysis unit 330 or the microscope system 390. The spontaneous etching process is schematically illustrated at the bottom of image 1350 in FIG. 13.

[0156] Alternatively, the unobserved spontaneous etching process can be stopped after a given period of time, any remaining particle residue imaged by analysis unit 330 and / or microscope system 390 to estimate the remaining etching time, and then the etching process can be continued for the estimated remaining time. If necessary, the spontaneous etching process can be repeatedly stopped to analyze any remaining particle residue and then continued again.

[0157] Figure 14 presents, in schematic form, the removal of particles 320 by an EBIE process. The upper part of image 1400, similar to Figure 8, shows that the chemical composition of particles 320 to be removed is analyzed by analysis unit 330. Based on measurement data by detector 340 of analysis unit 330, analysis unit 330 determines the elemental constituents of particles 320. Analysis unit 330 then identifies a matching gas 1470 suitable for performing the EBIE process.

[0158] 8, the analysis unit 330 can similarly analyze the composition of the substrate 310 surrounding the particles 320, and that composition can be taken into account when determining the matching gas 1470. For example, metallic molybdenum can be etched with the etching gas XeF2. The matching gas 1470 used to remove particles 320 having silicon as a primary constituent can be a mixture of XeF2 and water vapor (H2O). This matching gas 1470 can also remove ruthenium-containing particles 320. Particles 320 having organic materials as a primary constituent can similarly be etched with a matching gas 1470 including XeF2 and H2O. Particles 320 having tin (Sn) as the primary constituent can be removed from the substrate 310 in an EBIE process using a matching gas 1470 including ammonia (NH), hydrogen (H), nitrosyl chloride (NOCl), ammonium carbamate (HNCOONH), and / or ammonium carbonate ((NH)CO).

[0159] If necessary, a passivation gas may be added to the conditioning gas 1470 to prevent damage to the substrate 310 by the EBIE process. As described with reference to FIG. 9, it is also possible to apply a localized protective layer 950 (not shown in FIG. 14) around the particles 320 to be removed. Furthermore, one or more micromanipulators 620, 1120 may be positioned near the substrate 310 to protect the substrate 310 during etching of the particles 320 to be removed from the substrate 310. However, these protective measures are usually not necessary because the EBIE process is limited to the area of ​​the point of incidence of the particle beam 350 and therefore provides good lateral control.

[0160] The bottom part of image 1450 in FIG. 14 shows the implementation of an EBIE process using a harmonizing gas 1470 locally induced by a focused electron beam 350. The induced etching process can be stopped after a certain period of time for inspection of remaining particle residue by analysis unit 330 and / or microscope system 390. Image data of the remaining particle residue is used to determine the remaining etching time for the particle residue. If necessary, stopping the etching process for analysis of the etching results can be repeated several times.

[0161] In an alternative embodiment (not shown in FIG. 14), an electron beam 350 from analysis unit 330 may be used to perform the EBIE process, and a microscope system 390 may be used to observe the progress of the etching process.

[0162] In another embodiment, the analysis step for the particles 320 to be removed, shown at the top of image 1450 in FIG. 14, can be omitted. Instead, the particles 320 can be removed from the substrate 310 in an EBIE process using standard etching gases, such as XeF or nitrosyl chloride (NOCl). However, if subsequent images of the particles 320 or particle residue show that the standard etching process was unsuccessful or not entirely successful, the particles 320 or particle residue can be analyzed for their chemical composition, the matching gas 1470 identified, and a particle-specific etching process performed.

[0163] If, despite the above-mentioned protective measures, the particle etching process also affects the substrate 310, a reorganization process can be performed downstream of the etching process. For this purpose, a gas injection system 360 supplies a reorganization gas to the damaged area. The reorganization gas used can be, for example, a metal carbonyl, in particular chromium hexacarbonyl (Cr(CO)6), alone or together with nitrogen dioxide (NO2), and / or TEOS, also alone or together with nitrogen dioxide (NO2). This reorganization gas can be stored in a seventh reservoir 450 of the apparatus 400. The reorganization gas is locally excited by a particle beam 350 from the analysis unit 330, thus initiating a local EBID (electron beam induced deposition) process. The analysis unit 330 and / or the microscope system 390 can be used to monitor the reorganization process on the substrate 310.

[0164] 15 schematically illustrates another example of removing particles 320 from a substrate 310. This particle removal process can be performed particularly when the particles 320 have a low melting point and can form a metal alloy with a micromanipulator 1520. The micromanipulator 1520 may be one of the micromanipulators 520, 620, or 720 of the micromanipulator units 510, 610, or 710. For example, if the micromanipulator 1520 includes bismuth or a bismuth coating, a particle 320 having tin (Sn) as its primary constituent can be dissolved by the micromanipulator 1520. To activate this process, the particle 320 must be heated to at least its melting point.

[0165] The top of image 1550 in FIG. 15 illustrates contacting a micromanipulator 1520 with a particle 320 to be removed. The micromanipulator 1520 can be heated by an ohmic resistor built into the micromanipulator 1520 and applying a voltage to the ohmic resistor. To speed up the particle removal process, the micromanipulator 1520 can be warmed or heated even before contacting the particle 320. Heat transfer from the tip 1510 of the micromanipulator 1520 to the particle 320 heats the particle to its melting point. Once the melting point of the particle 320 is reached, the particle melts into the micromanipulator 1520. This process is depicted schematically in the bottom of image 1550 in FIG. 15. The particle 320 is melted by the micromanipulator 1520, forming a corresponding metal alloy 1570 with the micromanipulator 1520.

[0166] In an alternative heating process, the particles 320 and the micromanipulator 1520 can be heated by a particle beam 350 from the analysis unit 330 and / or by a photon beam from the microscope system 390. A combination of electrical heating by an ohmic resistance and heating by the particle beam 350 is of course possible as well.

[0167] In another embodiment (not shown in FIG. 15), the micromanipulator 1520 can include carbon nanotubes (CNTs) or multi-walled carbon nanotubes (MWCNTs). CNTs and MWCNTs can be electrically soldered and therefore have an adhesive effect on or are wettable by metals. CNTs and MWCNTs, especially when heated, can pick up particles 320 having metal as the main constituent.

[0168] Another way to remove the conductive particles 320 from the substrate 310 is to dissolve them by electromigration (not shown in FIG. 15). For this purpose, the particles 320 must be brought into contact with the conductive micromanipulator 1520. A further prerequisite for implementing this particle removal mode is a conductive substrate 310, so that a current flow can be established from the substrate 310 through the particle 320 to the micromanipulator 1520. To establish a closed circuit through the particle 320, the sample stage 402 and the micromanipulator unit supporting the micromanipulator 1520 may have electrical terminals for a voltage source. The potential of the sample stage 402 is transferred to the conductive particles 320 by electrical connection means. The electrical terminals of the voltage source, which may be part of the device 300, 400, are connected to the connection means of the sample stage 402, the connection means of the micromanipulator unit, and the connection means of the mounting of the micromanipulator 1520.

[0169] Electromigration occurs as a result of momentum transfer from the moving conduction electrons to the metal ions in the crystal lattice. To dissolve the conductive particles 320 by transporting their metal ions toward the micromanipulator 1520, it is advantageous to conduct a DC current through the particles 320. The positive pole of the circuit must also be connected to the micromanipulator 1520. As a result, the metal ions of the particles 320 move toward the micromanipulator 1520. Since there is an increase in electromigration with increasing current density in the particles 320, it is advantageous to select the maximum current density in the particles 320 to be removed.

[0170] It is further advantageous to promote the electromigration effect in the particle 320 by heating the particle 320. Heating can be achieved firstly by heating the micromanipulator 1520 as described above and by heat transfer to the particle 320. It is also possible to heat the particle 320 by irradiating it with a particle beam 350 from the analysis unit 330. It is of course also possible to heat the particle 320 to be removed by electromigration through a combination of heat transfer from the micromanipulator 1520 and irradiation with the particle beam 350.

[0171] 16 illustrates the removal of a particle 320, which includes two parts 1620 and 1630 that are only loosely attached in the illustrated example. The unstable particle 320 is to be removed from the substrate 310 by picking it up with the micromanipulator 1120. Without prior stabilization of the unstable particle 320, the unstable particle 320 risks breaking down into its two or more constituent parts 1620, 1630 when picked up by the micromanipulator 1120. Distinguishing between the two or more constituent parts 1620, 1630 and removing the individual pieces 1620, 1630 would clearly increase the complexity of particle removal compared to picking up the particle 320 en bloc from the substrate 310.

[0172] To prevent the unstable particle 320 from breaking apart when moved by the micromanipulator 1120, the unstable particle 320 is stabilized in a first step by depositing a material specifically on the area connecting the portions of the particle 1620, 1630. To stabilize the unstable particle 320, a deposition gas 1610 stored in one of the two reservoir vessels 430 or 435 of the apparatus 400 is supplied to the connecting area of ​​the unstable particle 320 by a gas injection system 360. The deposition gas 1610 may contain a metal carbonyl, for example, molybdenum hexacarbonyl (Mo(CO)6) and / or tungsten hexacarbonyl (W(CO)6). Alternatively, carbon-rich hydrocarbon compounds, such as unsaturated aromatic hydrocarbons, especially styrene, can be used to stabilize the unstable particle 320.

[0173] Particle beam 350 from analysis unit 330 initiates a localized EBID process with deposition gas 1610 that deposits material onto unstable particle 320, preferably onto the region connecting two particle components 1620 and 1630. This deposition process is shown schematically at the top of image 1600 in FIG. 16. The deposition of material onto unstable particle 320 can be observed by microscope system 390. Alternatively, the deposition process can be stopped at periodic intervals and the analysis unit 330 can be used to image unstable particle 320.

[0174] The bottom part of image 1650 in Figure 16 shows schematically stabilizing particles 1670 stabilized by material 1660 deposited in the connection region, which are removed en masse from substrate 310 by picking them up with micromanipulator 1120 in a second step.

[0175] In the example shown in Figure 16, unstable particle 320 includes two components 1620 and 1630. However, unstable particle 320 can also have three or more components (not shown in Figure 16) that are only loosely attached to one another. Furthermore, the stabilization process described above in the context of the top of image 1600 can be used to join particle portions or clusters of particle fragments to create a single particle (not shown in Figure 16) that can be more easily handled and removed en masse from substrate 310 in a controlled manner by picking it up with micromanipulator 1120.

[0176] 17-19 illustrate another two-step process for removing particles 320 from a substrate 310. As illustrated by way of example in FIG. 17, particles 320 are connected or fused to the substrate 310 by a type of particle base 1710. As illustrated in FIG. 17, a micromanipulator 1120 moves toward the particle 320. In a second step, illustrated in FIG. 18, the particle 320 is picked up or lifted from the substrate 310 by mechanical contact with the micromanipulator 1120. In this process, the entire particle 320 is not separated from the substrate 310. Instead, the bond between the particle base 1710 and the particle 320 breaks, leaving the particle base 1710 on the surface of the substrate 310 as particle residue 1810.

[0177] 19 illustrates removing particle residue 1810 from substrate 310 by performing an EBIE process using a gas 1470 that is matched to particles 320 or particle residue 1810. By determining the matching gas 1470, it is possible to analyze the chemical composition of the particles 320 being removed (not shown in FIG. 19) and / or use analysis unit 330 to confirm the material composition of particle residue 1810. If necessary, the modifications discussed above in the context of FIGS. 8-14 can also be used to remove particle residue 1810.

[0178] Finally, flow chart 2000 of Figure 20 presents the essential steps of a method for removing at least one single particle 320 from a substrate 310. The substrate 310 may be provided with an optical element in the EUV wavelength range and / or an EUV mask.

[0179] The method starts in step 2010. In step 2020, at least one constituent of the material composition of at least one particle 320 is determined. For this purpose, an analysis unit 330 can be used.

[0180] In step 2030, a gas 370, 1470 matched to a particular constituent of the material composition is provided in the environment of the at least one single particle 320, the matching gas 370, 1470 contributing to removing the at least one single particle 320 from the substrate 310. The matching gas 370, 1470 may be provided by the gas injection system 360. The method then ends in step 2040. [Explanation of symbols]

[0181] 100 Photolithography mask 110 Substrate 120 pattern elements 130 pattern elements 140 pattern elements 150 particles 200 Photolithography Mask 220 Contact Hole 250 particles 260 particles 300 equipment 305 Arrow 310 Substrate 320 particles 325 Sample stage 330 analytical units 335 Particle Beam Source 340 detector 345 particles 350 particle beams 355 detector 360 Gas Injection System 370 Harmonized Gas 380 Control Unit 385 Connecting part 390 Microscope System 395 Micromanipulator Unit 400 equipment 401 Scanning Electron Microscope (SEM) 402 board 403 3-point support mechanism 404 Sample stage 406 Electronic Cannon 408 Beam Imaging Element 409 Electron Beam 410 Focused electron beam 412 Beamforming Elements 414 detector 416 Ion Gun (Flood Gun) 418 Control Unit 419 screens 420 Computer Systems 422 Pump System 425 First Reservoir Container 426 Control valve 427 Gas Injection System 430 Secondary Reservoir Container 432 Gas Injection System 435 Reservoir container 437 Gas Injection System 440 Reservoir Container 441 Control valve 442 Gas Injection System 445 Reservoir Container 446 Control Valve 447 Gas Injection System 450 Reservoir Container 452 Gas Injection System 457 Gas Injection System 461 Control valve 462 Gas Injection System 465 Scanning probe microscope in the form of atomic force microscope (AFM) 467 Measuring Head 470 Micromanipulator Unit 475 Scanning probe microscope in the form of atomic force microscope (AFM) 477 Measuring Head 480 Micromanipulator Unit 485 Vacuum Chamber 500 Diagram 510 Micromanipulator Unit 520 Micromanipulator Unit 530 Mounting part 600 Diagram 610 L-type Micromanipulator Unit 620 Ladle-shaped Micromanipulator 630 Mounting part 700 Diagram 710 Micromanipulator Unit 720 Micromanipulator 750 Notch or recess 800 statues 850 statue 950 Localized Protection Layer 970 Metal Carbonyl Deposition Gas 1120 Micromanipulator 1140 Tip 1300 statues 1350 statue 1400 statues 1450 statue 1470 Harmonized Gas 1500 statues 1520 Micromanipulator 1550 statue 1570 Metal alloys 1600 statues 1610 Deposition Gas 1620 Particle Composition 1630 Particle Composition 1650 statue 1660 Material 1670 Stabilizing Particles 1710 particle-based 1810 Particle Residue

Claims

1. An apparatus (300, 400) for removing at least one single particle (320) from a substrate (310, 402), in particular from an optical element for extreme ultraviolet (EUV) photolithography, comprising: an analytical unit (330) designed to determine at least one constituent of the material composition of said at least one single particle (320); b. at least one gas injection system (360) designed to supply a gas (370, 1470) matched to a specific composition in the environment of said at least one single particle (320); c) an apparatus (300, 400) wherein the matching gas (370, 1470) contributes to removing the at least one single particle (320) from the substrate (310).

2. 2. The apparatus (300, 400) of claim 1, wherein the analysis unit (330) utilizes at least one element from the group consisting of the following techniques: Energy Dispersive X-ray Spectroscopy (EDX), X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Secondary Ion Mass Spectroscopy (SIMS), Secondary Neutral Mass Spectroscopy (SNMS), Rutherford Backscattering Spectroscopy (RBS), and Low Energy Ion Scattering Spectroscopy (LEIS).

3. 3. The apparatus (300, 400) of claim 1 or 2, wherein the analysis unit (330) is designed to take into account external inputs when determining the at least one constituent of the material composition.

4. The apparatus (300, 400) of any one of claims 1 to 3, further comprising a machine learning model trained to predict the at least one constituent of the material composition of the at least one single particle (320) using measurement data from the analysis unit (330).

5. 5. The apparatus (300, 400) according to any one of claims 1 to 4, further comprising at least one microscope system (390) designed to image the at least one single particle (320), preferably during removal of the at least one single particle (320).

6. The apparatus (300, 400) of any one of claims 1 to 5, wherein the matching gas (370) spontaneously etches the at least one single particle (320).

7. 7. The apparatus (300, 400) of claim 6, wherein the harmonic gas (370) spontaneously etches the at least one single particle (320) at a rate greater than the spontaneous etching rate of the substrate (310), such as at least 2 times, preferably at least 5 times, more preferably at least 10 times, and most preferably at least 30 times the spontaneous etching rate of the substrate (310).

8. The at least one single particle (320) comprises tin (Sn), and the matching gas (370, 1470) comprises at least hydrogen (H 2 8. The apparatus (300, 400) according to any one of claims 1 to 7, comprising at least one hydrogen compound and / or at least nitrosyl chloride (NOCl).

9. 6. The apparatus (300, 400) of claim 1, further comprising at least one particle beam (350) that initiates a local etching reaction of a first harmonic gas (370, 1470) that etches the at least one single particle (320) and / or initiates a local deposition reaction of a second harmonic gas (1470) that deposits material onto the at least one single particle (320).

10. The at least one single particle (320) comprises tin, and the at least one first matching gas (370, 1470) comprises a hydrogen compound, hydrogen (H 2 10. The device of claim 9, comprising at least one member from the group consisting of: halogen compounds, chlorine compounds, and nitrosyl chloride (NOCl).

11. The device (300, 400) according to any one of claims 1 to 10, further comprising at least one micromanipulator unit (510, 610, 710) designed to interact with said at least one single particle (320).

12. The device (300, 400) of claim 11, wherein the at least one micromanipulator unit (510, 610, 710) includes at least one micromanipulator (520, 620, 720, 1120), and the at least one micromanipulator unit (510, 610, 710) is designed to heat the at least one micromanipulator (520, 620, 720, 1120).

13. 13. The apparatus (300, 400) of claim 11 or 12, wherein the at least one micromanipulator (1520) is designed to include a metal or metal alloy that forms an alloy (1570) with at least one single molten particle (320).

14. The apparatus (300, 400) of any one of claims 11 to 13, wherein the at least one micromanipulator (1520) comprises bismuth (Bi) or a bismuth alloy, and at least one constituent of the material composition of the at least one single particle (320) comprises tin (Sn).

15. The apparatus (300, 400) of any one of claims 1 to 14, further comprising a voltage source (1520) designed to generate a current flow between the at least one micromanipulator (1520) and the at least one single particle (320) that causes electromigration in the at least one single particle (320).

16. 16. The apparatus (300, 400) of claim 1, wherein the at least one single particle (320) comprises one member of the group consisting of particles that are unstable with respect to removal from the substrate (310), particles having two or more particle fragments (1620, 1630), and particles that include particle agglomerates, and the gas injection system (360) is further designed to supply a matching gas (1470) in an environment of the at least one single particle (320) prior to the removal, the matching gas depositing material on the at least one single particle (320).

17. 17. The apparatus (300, 400) according to any one of claims 11 to 16, wherein the micromanipulator unit (510, 610, 710) is designed to remove a first portion of the at least one single particle (320), and the harmonic gas (370, 1470) contributes to removing a second portion of the at least one single particle (320) by spontaneous etching and / or particle beam induced etching.

18. The apparatus (300, 400) of any one of claims 1 to 17, wherein the gas injection system (360) is also designed to supply, after removal of the at least one single particle (320), a reorganization gas in an environment of the removed at least one single particle (310) that at least partially eliminates damage to the substrate (310) caused during removal of the at least one single particle (310).

19. A method (2000) for removing at least one single particle (320) from a substrate (310), in particular from an optical element for extreme ultraviolet (EUV) photolithography, comprising: determining (2020) at least one constituent of the material composition of said at least one single particle (320); b. providing (2030) a gas (370, 1470) matched to the specific constituents of the material composition in the environment of the at least one single particle (320); c) The method (2000), wherein the matching gas (370, 1470) contributes to removing the at least one single particle (320) from the substrate (310).

20. A computer program comprising instructions which, when executed by the computer program, cause an apparatus (300, 400) according to any of claims 1 to 18 to perform the method steps according to claim 19.

Images