Method and apparatus for mask repair - Patents.com

Abstract

The present invention relates to a method, an apparatus and a computer program for treating an object for lithography. The method for treating an object for lithography comprises: providing a first gas containing first molecules; providing a particle beam to a processing area of ​​the object based at least in part on the first gas to remove a first material in the processing area. The first material may comprise chromium and nitrogen. Furthermore, the first material may comprise at least 5 atomic percent nitrogen, preferably at least 10 atomic percent nitrogen, particularly preferably at least 20 atomic percent nitrogen.

Description

[Technical field]

[0001] This patent application claims priority to German patent application DE 10 2022 202061.8, entitled “Verfahren und Vorrichtung zur Maskenreparatur”, filed with the German Patent and Trademark Office on March 1, 2022. German patent application DE 10 2022 202061.8 is incorporated by reference in its entirety into this patent application.

[0002] The present invention relates to a method, an apparatus and a computer program for processing an object for lithography. More particularly, the present invention relates to a method for removing material, to a corresponding apparatus and to a method for lithographic processing of a wafer and to a computer program for carrying out the method. [Background technology]

[0003] In the semiconductor industry, smaller and smaller structures are produced on wafers to ensure increased integration density. Among the methods used here for the production of structures are lithographic methods for imaging these structures on the wafer. Lithographic methods may include, for example, photolithography, ultraviolet (UV) lithography, DUV lithography (i.e. lithography in the deep ultraviolet spectral region), EUV lithography (i.e. lithography in the extreme ultraviolet spectral region), x-ray lithography, nanoimprint lithography, etc. A mask is typically used here as the object for lithography (e.g. photomask, exposure mask, reticle, stamp in the case of nanoimprint lithography, etc.), which contains, for example, a pattern for imaging the desired structure on the wafer.

[0004] During the course of lithography, masks may be subjected to high physical and chemical stresses (e.g., during mask exposure, mask cleaning, etc.), and therefore there is a high demand for the stability of mask materials, which may become even more demanding as technological developments in lithography progress.

[0005] However, mask errors generally cannot be eliminated in complex mass production, so mask material may appear on the mask as mask errors (e.g., as defects, excess material, abnormally formed material, overlapping particles, etc.).

[0006] It is generally known that mask errors can be corrected or repaired, for example, via particle beam based etching processes. However, existing methods of mask repair only consider a limited number of mask materials.

[0007] Thus, the problem addressed by the present invention is to specify a method and apparatus for optimizing the processing of an object for lithography. Summary of the Invention

[0008] This objective is achieved, at least in part, by various aspects of the present invention.

[0009] A first aspect of the present invention relates to a method for treating an object for lithography. The method of the first aspect includes providing a first gas comprising a first molecule. The method further includes providing a particle beam to a working region of the object to remove a first material in the working region based at least in part on the first gas. The first material may include chromium and nitrogen. Furthermore, the first material may include at least 1 atomic percent (at %) of nitrogen, preferably at least 5 atomic percent (at %) of nitrogen, more preferably at least 10 atomic percent of nitrogen, and particularly preferably at least 20 atomic percent of nitrogen.

[0010] The present invention addresses the problem of removing material on lithographic objects that are designed to withstand removal under chemical and / or physical stress.

[0011] Recently established chromium-containing mask materials are specifically designed with a specific nitrogen content to meet current and future demands. The nitrogen content can be increased here stoichiometrically (e.g., beyond the level of nitrogen contamination) for established chromium-containing mask materials. Thanks to the specific nitrogen content, the mask materials can have high chemical stability for lithography demands. These nitrogen-containing mask materials can, for example, constitute a layer of a mask (e.g., a layer of a pattern element).

[0012] For example, a chromium-containing material may be specifically designed with a high nitrogen content of at least 1 atomic percent (at least 5 at%, at least 10 at%, and / or at least 20 at%) to significantly prevent removal of this chromium-containing material under chemical / physical influences. The high nitrogen content may be designed to prevent removal / wear of the chromium-containing material even under sustained or normal chemical / physical stress. These types of chromium-containing resistant materials are typically designed for the extreme conditions of the lithographic method under which the object may be used for lithography. For example, the object may be exposed to a (damaging) plasma during the lithographic method. For example, the lithographic method may require exposing the object to a hydrogen environment (e.g., to prevent defects). In the case of lithographic exposure of the object, there may be the release of a (parasitic) highly reactive hydrogen plasma with free hydrogen radicals that can act on the material of the object. The plasma constitutes a high degree of chemical / physical stress for the object and may cause removal of material of the object and damage of the material (e.g., in a manner similar to plasma etching). However, material removal effects are undesirable in lithographic objects, since they can adversely affect the properties of the object and therefore the quality of the lithographic method. Thus, a high nitrogen content in the chromium-containing material may be (explicitly) designed to ensure high resistance of the first material to the material removal effects of the plasma (e.g., especially of highly reactive hydrogen plasma). Furthermore, the object may be exposed to numerous other mechanical / chemical effects in lithography, which may damage the object (e.g., together with the action of the plasma). For example, other damaging effects may include severe temperature fluctuations, exposure to radiation, and chemical reactions of the object with the purge gas. Thus, a high nitrogen content is typically designed to essentially cancel out the entirety of the damaging material removal effects in lithography, making the mechanical / chemical wear and removal of the chromium-containing material more difficult.

[0013] The inventors realized that this material can also be removed in a particle beam-induced manner to correct any defects caused by the excess material. The basis of the concept of the present invention is therefore the removal of a material that is specifically designed to withstand removal via a particle beam-based process. The inventors have made the unexpected discovery that a chromium-containing material with a high nitrogen content of at least 1 atomic percent (at least 5 atomic percent, at least 10 at%, and / or at least 20 at%) can be removed with the aid of a provided gas and a provided particle beam (e.g., via particle beam-induced etching). This was a surprising discovery for the inventors, since they could not have foreseen that a first material that is resistant to the aggressive conditions of lithography can be treated or even removed in a particle beam-based manner (e.g., without using a plasma that is known to be able to etch lithographic objects). Furthermore, the inventors did not expect that in view of the resistant first material, the provision of a gas containing first molecules would in principle be sufficient for the particle beam-based removal of the first material. According to the invention, it is not necessary to resort to complex gas mixtures (e.g., containing various types of molecules designed for resistant materials). This can ensure a reduction in the complexity of the particle beam reduced removal, which allows, for example, easier process control of the method according to the invention (e.g., because providing a single gas is less demanding for technical implementation than providing a gas mixture of, for example, two or more different gases). Thus, the invention allows the processing of lithographic objects containing resistant materials (e.g., containing a high nitrogen content).

[0014] The unit of "atomic percentage" described herein may relate to the molar ratio of the corresponding material, where the atomic percentage indicates, for example, the relative number of particles (e.g., nitrogen atoms) to the total number of particles of a substance (e.g., the total number of atoms of a first material). The atomic percentage may be detected, for example, via secondary ion mass spectroscopy, SIMS, and / or Auger electron spectroscopy, and / or x-ray photoelectron spectroscopy, XPS (and also, for example, via photoelectron spectroscopy, PES).

[0015] The lithographic object described herein may include a lithography mask. The lithography mask may be designed for use in lithography (e.g., in exposing a semiconductor-based wafer) to produce a semiconductor-based chip. The lithography mask may include any type of lithography mask that can image an image based on an electromagnetic radiation source (of any wavelength) and a pattern contained in the lithography mask. The image may include a transformation of the pattern. The lithography mask may include, for example, an EUV mask, a DUV mask, a UV mask, an x-ray lithography mask, a binary mask, a phase shift mask, etc. Additionally, the lithography mask may include a nanoimprint lithography stamp, or a lithography mask that can image a pattern based on a source of particles.

[0016] A processing area as specified herein may include a localized area of ​​a lithographic object. However, it is also contemplated that the processing area may include the entirety of a lithographic object. The processing area may include any areal dimension, shape, and / or geometry. For example, the processing area may be within a range of an order of magnitude related to a particular measurement of the object. For example, the particular measurement may include a critical dimension CD of a pattern element of the object. The critical dimension CD may include, for example, a width of a defined structure of the pattern element or a defined distance between two (characteristic) pattern elements. The processing area may, for example, define an area A that exceeds the critical dimension CD of the pattern element (e.g., A may correspond to a function of the critical dimension CD, e.g., A=f(CD); e.g., A may be proportional to the critical dimension). Furthermore, the first material may be removed within the processing area such that the first material is not necessarily removed over the entire area of ​​the processing area, but is removed (locally) in a sub-area of ​​the processing area. Alternatively, the removal within the processing region can be performed such that the first material is removed over the entire area of ​​the processing region. Furthermore, the first gas may be provided in a controlled manner (e.g., via a locally positionable gas conduit with a gas nozzle) in a sub-region of the processing region. It is likewise possible to provide a particle beam in that the particles of the particle beam are directed onto a sub-region of the processing region so as to be incident on the sub-region. Furthermore, the method may include a specific local control and / or focusing of the particle beam within the sub-region or processing region (e.g., to locally control the reaction of the particle beam induced etching).

[0017] The method in the first aspect described herein is essentially contemplated with different nitrogen contents of the first material, for example with nitrogen contents <5 atomic percent or even <1 atomic percent or >50 atomic percent. Accordingly, a further aspect of the invention may comprise the removal of a first material by a provided first gas and a provided particle beam, which further aspect may comprise at least one or more of the features described herein, without being limited to the nitrogen content of the first material.

[0018] The inventors further understood that the methods described herein can be considered with respect to materials as the first material that include a different element (e.g., a different metal) other than (or in addition to) chromium. The first material can therefore be considered a nitrogen-based material (e.g., a nitride-based material, e.g., a metal nitride). For example, the first material other than chromium can include at least one of the following: niobium, titanium, and / or tantalum. Here, the first material can include, for example, niobium nitride (e.g., NbN, Nb2N, Nb4N3) and / or titanium nitride (e.g., TiN), which can be removed by the methods described herein. The nitrogen content of the niobium nitride and the titanium nitride here can correspond to the nitrogen content described herein in the first material.

[0019] In one embodiment, in the method of the first aspect, the first material is capable of absorbing radiation associated with the object. For example, this radiation associated with the object may include electromagnetic radiation with a specific wavelength that may be used in a lithography method for which the object is designed. For example, the radiation associated with the object may correspond to the exposure radiation of the object in a lithography method. The specific wavelength of the exposure radiation may be considered as the lithography wavelength of the object. In one embodiment, the lithography object includes an EUV mask for an EUV lithography method, in which the lithography wavelength (i.e. the wavelength of the exposure radiation) may be 13.5 nm. Furthermore, depending on the object, the radiation may relate to, for example, a DUV lithography method (e.g. with a lithography wavelength of 193 nm or 248 nm), an i-line lithography method (e.g. with a lithography wavelength of 265 nm), or any other lithography method (e.g. with a different lithography wavelength).

[0020] In one embodiment, the first material has intrinsic material parameters (e.g., absorption coefficient, magnitude of absorption, imaginary part of the refractive index of the first material) that can be used to terminate significant (e.g., high) absorption of the object at the lithography wavelength. Additionally, the first material may include a material that is typically present in the object to absorb the lithography wavelength (e.g., a material that corresponds to an absorbing layer of the object (e.g., for a pattern element)).

[0021] In other examples, the first material does not have only one inherent material parameter per se that can be used to terminate significant absorption. Furthermore, the first material may be geometrically configured to effectively absorb radiation associated with the object in a localized region of the object. For example, the first material may be geometrically formed to cause significant absorption of radiation at the lithography wavelength in the (localized) region of the object through its absorbing material properties and its geometric structure. In this case, the first material in the (localized) region may contribute to imaging in the lithography method since there is actual (i.e., effective) absorption of radiation at the lithography wavelength. The geometry of the first material may be determined, for example, through the layer thickness of the material or through the distance (e.g., absorption distance) that can be covered by radiation at the lithography wavelength in the lithography method through the first material. The absorption distance may take into account, for example, optical diffraction of radiation at the lithography wavelength or the incidence vector of the exposure radiation. For example, the method may include not removing a very thin layer of absorbing material (i.e., an inherently absorbing material) because, from a geometrical point of view, the thin layer cannot significantly absorb radiation at the lithographic wavelength and therefore does not contribute to real (i.e., effective) imaging in the corresponding lithographic method. For example, significant absorption may be determined or calculated by the layer thickness or absorption distance of the first material. The layer thickness of the first material may be at least 20 nm, preferably at least 35 nm, more preferably at least 50 nm, and most preferably at least 60 nm. However, the layer thickness of the first material may alternatively be less than 60 nm, for example less than 50 nm, or less than 35 nm. Significant absorption may be described as a 70% attenuation of radiation intensity at the lithographic wavelength (across the first material) in the lithographic method, preferably 80% attenuation, and most preferably 90% attenuation.

[0022] In one embodiment, in the method of the first aspect, the first material corresponds to a layer material of a pattern element of the object. In one embodiment, in the method, the layer material corresponds to a material of an absorbing layer of the pattern element. The absorbing layer may comprise a layer of the pattern element that is explicitly configured for absorption of radiation at a lithographic wavelength.

[0023] In one embodiment, the method includes a first material comprising at least 10 atomic percent chromium, preferably at least 20 atomic percent chromium, most preferably at least 30 atomic percent chromium. In a further embodiment, the method includes a first material comprising at least 10 atomic percent chromium oxide, preferably at least 20 atomic percent chromium oxide, most preferably at least 30 atomic percent chromium oxide. In a further embodiment, the method includes a first material comprising at least 2 atomic percent chromium in the metal compound, preferably at least 3 atomic percent chromium in the metal compound, most preferably at least 4 atomic percent chromium in the metal compound. The atomic percentages can be detected, for example, via secondary ion mass spectroscopy, SIMS, and / or Auger electron spectroscopy, and / or x-ray photoelectron spectroscopy, XPS (and also, for example, via photoelectron spectroscopy, PES). In particular, the molar ratio of metallic chromium can be detected via XPS analysis.

[0024] In one embodiment, in the method of the first aspect, the first material comprises chromium nitride. The chromium nitride may, for example, comprise CrN and / or Ce2N. The chromium nitride may be notable for high hardness and extreme corrosion resistance. The inventors have realized that chromium nitride or materials having chromium nitride content may be treated or removed by the method according to the invention. The chromium nitride may, for example, be detected via standard physical / chemical analytical methods (e.g., via x-ray spectroscopy). For example, CrN may have a refractive index n of 0.9295 and an absorption coefficient kβ of 0.0336. For example, Cr2N may have a refractive index n of 0.9272 and an absorption coefficient kβ of 0.0376.

[0025] In one embodiment, the first gas may be considered as a main etching gas for the removal of the first material. The first gas may here be designed to have a substantial effect on the etching properties of the first material. For example, the molecules of the first gas may be selected to have an etching / removal effect on the first material. Alternatively, the first molecules may be selected to have an etching / removal effect on the first material in conjunction with a particle beam induced reaction.

[0026] In one embodiment, in the method of the first aspect, the first molecule of the first gas contains at least one halogen atom. The inventors have realized that gases that are particularly suitable for removing the resistant first material (e.g., having the highest nitrogen content as described herein) are gases that contain molecules that contain halogens. Such first gases (i.e., etching gases) in combination with the provided particle beam can advantageously remove the resistant first material in a technically desirable manner. For example, such first gases can avoid residue removal, long etching times, and inhomogeneous material removal in the method of the first aspect.

[0027] In one embodiment, in the method of the first aspect, the first molecule comprises a halogen compound. For example, the halogen compound may comprise a compound comprising at least one halogen atom, which enters the compound with at least one additional chemical component (e.g., any additional chemical element / atom, and / or additional chemical group / substance compound, etc.). In one embodiment, the halogen compound may exclusively comprise the same type of halogen (e.g., the first molecule may comprise F2, Cl2, Br2, etc.).

[0028] In one embodiment, in the method of the first aspect, the halogen compound comprises a nitrosyl halide and / or a nitrile halide. In one embodiment, in the method of the first aspect, the nitrosyl halide comprises at least one of the following: nitrosyl chloride, NOCl, nitrosyl fluoride, NOF, nitrosyl bromide, NOBr. In a further embodiment, in the method of the first aspect, the nitrile halide comprises at least one of the following: nitrile chloride, ClNO2, nitrile fluoride, FNO2. The inventors have now realised that such first molecules (e.g., nitrosyl halides or nitrile chlorides) can also advantageously remove resistant first materials in a technically desirable manner in the context of the method of the first aspect.

[0029] In one embodiment, the halide compound comprises a noble gas halide, for example, the noble gas halide may comprise a compound that includes at least one halogen atom and at least one noble gas atom.

[0030] In one embodiment, the noble gas halide comprises at least one of the following: xenon difluoride, XeF2, xenon dichloride, XeCl2, xenon tetrachloride, XeCl4, xenon tetrafluoride, XeF4, xenon hexafluoride, XeF6. The inventors have now realised that such noble gas halides (e.g., xenon difluoride, in particular) may also advantageously remove the resistant first material in a technically desirable manner in the context of the method of the first aspect.

[0031] In a further embodiment, the first molecule comprises a quadrupole moment (or a multipole moment having at least four poles) greater than zero. For example, xenon difluoride may have a quadrupole moment greater than zero.

[0032] In one embodiment, the halogen compound includes an interhalogen (e.g., an interhalogen). For example, the interhalogen may include compounds of at least two different halogens with respect to one another. The inventors have recognized that interhalogens are also suitable as the first molecule of the first gas for removal of the resistant first material in a technologically desirable manner. For example, the interhalogen may include at least one of the following: ClF, ClF3, BrF, BrF3, ICl, ICl3, BrCl, IF, IF3, IBr, IBr3.

[0033] In further embodiments, the first gas includes a combination of first molecules as specified herein. The first gas may be considered as a combination of different gases having different first molecules. For example, the first gas may include any combination of one or more nitrosyl halides, nitrile halides, noble gas halides, and / or interhalogens as first molecules.

[0034] For example, the first gas may include a nitrosyl halide and a noble gas halide, where the first gas may include, for example, NOCl and / or NOF as the nitrosyl halide and XeF2 as the noble gas halide.

[0035] For example, the first gas may include a nitrile halide and a noble gas halide, where, for example, the first gas may include ClNO2 and / or FNO2 as the nitrile halide and XeF2 as the noble gas halide.

[0036] For example, the first gas may include a nitrosyl halide and a nitrile halide, where the first gas may include, for example, NOCl and / or NOF as the nitrosyl halide and ClNO2 and / or FNO2 as the nitrile halide.

[0037] In one embodiment, the first molecule comprises a polar molecule. It has been found that polar molecules having a dipole moment may in principle be suitable for the process. In a further embodiment, the first molecule may comprise an apolar molecule. The invention is also based on the concept that apolar molecules having no dipole moment may in principle be suitable for the process. In a further embodiment, the first molecule comprises a triatomic molecule. According to the invention, there is no need necessarily for a complex compound having more than three atoms per molecule for a suitable method of the first aspect.

[0038] In one embodiment, in the method of the first aspect, the first dipole moment associated with the first molecule comprises at least 1D (D: Debye), preferably at least 1.5D, more preferably at least 1.7D, most preferably at least 1.8D. In a further embodiment, in the method, the first dipole moment comprises at least less than 2.5D, preferably at least less than 2.3D, more preferably at least less than 2.1D, most preferably at least less than 2D. The inventors have realized that the possibility of adhesion of the (first) molecule to a surface depends on their dipole moment (e.g., the possibility of adhesion can be proportional to the dipole moment). The present invention exploits this effect in the removal of the first material. In particle beam-based removal (e.g., particle beam induced etching), what is typically required to carry out the removal reaction in a defined manner is a defined (local) gas concentration of the first gas (i.e., etching gas) for a specific period of time. Therefore, it can be helpful to specifically adjust the defined (local) gas concentration. However, due to chemical and / or physical interactions in the removal of the first material, the defined (local) gas concentration may change to an extent that is technically undesirable. For example, this may include a (local) depletion of the first gas in the processing area, so that the process of removing the first material becomes affected in an undesirable manner. The inventors have now realized that the use of the first molecule with a dipole moment as described herein can suggest an improved state of adhesion potential of the first molecule on a surface (e.g., the surface of the first material). This can, for example, allow an optimized coverage of the first molecule in the processing area of ​​the object. This technical effect can therefore be used to achieve an optimized state in the configuration of the defined (local) gas concentration, optimizing the removal of the first material.

[0039] In one embodiment, the method of the first aspect further comprises providing a second gas comprising a second molecule, and the removal of the first material is further based at least in part on the second gas. The second gas described herein may in this context be considered as an additive gas relative to the main etching gas (i.e., the first gas). As an additive gas, the second gas may further affect the removal of the first material or the particle beam induced etching, for example, more precisely, to adapt the process parameters / results (e.g., etch rate, anisotropy factor, selectivity, sidewall angle, surface roughness, etc.). In principle, the features described herein for providing the first gas may be applicable to providing the second gas, and vice versa.

[0040] In one embodiment, in the method of the first aspect, the first dipole moment associated with the first molecule and the second dipole moment associated with the second molecule differ from each other by 0.1D or less, preferably 0.08D or less, more preferably 0.07D or less, most preferably 0.06D or less. This embodiment is based on the idea that a first molecule of a first gas (i.e., of a main etching gas) has a dipole moment similar to a second molecule of a second gas (i.e., of an additive gas). The inventors have realized that this situation can be used to advantage during the removal of a first material. In the particle beam-based removal described herein, what is typically required is a defined (local) gas concentration over a certain period of time in order to carry out the removal reaction in a defined manner. This becomes increasingly important, especially when using more complex gas mixtures that include at least two gases (e.g., a first gas and a second gas). This is associated with a high demand for maintaining a defined (local) gas concentration. For example, it is now possible to cause an increasing degree of (local) depletion of the second gas (and / or of the first gas) in the processing area, and thus the removal of the first material may be affected in an undesirable manner. The inventors have now realized that the use of first and second molecules with similar dipole moments (as described herein) may imply similar adhesion of the first and second molecules to the surface. Similar possibilities of adhesion of the first and second molecules may now arise, meaning that an even coverage of the surface by the first and second molecules may be possible. In particular, in this way, it is possible to cover the surface of the first material with the first and second molecules in a defined manner in the removal operation. With this technical effect, optimized conditions at defined configurations of (local) gas concentrations may be correspondingly enabled in the use of the first and second gases. This operating mechanism may accordingly specifically optimize the removal of the first material.

[0041] As described herein, the likelihood of adhesion of a molecule may be proportional to its dipole moment. Thus, in one embodiment, the method includes inclusion of the first and second dipole moments (as described herein) of the first and second molecules as parameters in removing the first material. For example, the first and second dipole moments may define process parameters (e.g., gas flow rates of the first and / or second gases) in the removal operation.

[0042] In one embodiment, the method includes providing the first gas and the second gas at least partially simultaneously. For example, the first gas and the second gas may be introduced into the environment of the processing area or into the environment of the object simultaneously, for example during the removal of the first material. This may include the (at least partial) presence of a first gas volumetric flow rate of the first gas and a second gas volumetric flow rate of the second gas during the removal, thus ensuring the presence of both gases in the processing area / object environment. Here, for example, it is possible that the first and second gas volumetric flows are essentially identical. However, in other embodiments, they may be different. The simultaneous provision of the first and second gases may include a variation of the first gas volumetric flow rate and the second gas volumetric flow rate (in the removal of the first material).

[0043] In one embodiment, the method includes providing the first gas and the second gas at least partially at a time interval. For example, the removal of the first material may require only one of the two gases to be provided or introduced into the environment of the processing area / object in the method step of removal. For example, it may require only the first gas (or the second gas) to be initially introduced into the environment of the processing area / object at the start of the removal of the first material. The second gas (or the first gas) may then be provided or introduced at a later time. Furthermore, it is also conceivable that during the removal, there is a step change between the (exclusive) provision / introduction of the first gas (without the second gas) and the (exclusive) provision / introduction of the second gas (without the first gas). Furthermore, it is also possible that the end of the process of removing the first material includes the exclusive provision / introduction of one of the two gases. For example, it is conceivable that the end of the process of generating is determined by the exclusive provision / introduction of the second gas.

[0044] In one embodiment, in the method of the first aspect, the second molecules comprise water, H2O and / or heavy water, D2O. For removal of the resistant first material, water and / or heavy water have been found to be advantageous additive gases, also with regard to the selectivity of the removal of the first material. In a particularly advantageous embodiment, the method comprises NOCl as the first gas and H2O as the second gas. In a further particularly advantageous embodiment, the method comprises XeF2 as the first gas and H2O as the second gas. In a further embodiment, the second molecules of the second gas may comprise heavy water, HDO.

[0045] In further examples, the second gas (or second molecule) may include an oxygen-containing component, a halide, and / or a reducing component. The same can be applied to the fourth gas (or fourth molecule) described herein. The oxygen-containing component may include, for example, an oxygen-containing molecule. For example, the oxygen-containing component may include at least one of the following: oxygen (O2), ozone (O3), hydrogen peroxide (H2O2), nitrous oxide (N2O), nitric oxide (NO), nitrogen dioxide (NO2), nitric acid (HNO3). The halide may include, for example, at least one of the following: Cl2, HCl, XeF2, HF, I2, HI, Br2, HBr, NOCl, NOF, ClNO2, FNO2, PCl3, PCl5. The reducing component may include a molecule having a hydrogen atom. For example, the reducing component may include at least one of the following: H2, NH3, CH4.

[0046] In one embodiment, in the method of the first aspect, the first material is selectively removed such that the second material of the object is essentially not removed. For example, the method may be designed such that in the removal according to the invention (e.g. based on particle beam induced etching), there is a selectivity of removal (e.g. etch selectivity) with respect to the first material over the second material. The selectivity may, for example, allow the removal of the second material at a lower removal rate than the first material when the second material is subjected to the method (as described herein). Thus, in the method, a defined selectivity (e.g. high etch selectivity) is established. This can be ensured, for example, through a suitable selection of the first and / or second gas and suitable gas parameters of the first and / or second gas (e.g. gas mass flow rate, gas pressure, gas concentration, etc.). For example, it is particularly possible to use the selection of the second gas (e.g. water and / or heavy water as described herein) and the gas parameters of the second gas to adjust the selectivity of the removal of the first material relative to the second material. The method may also be performed such that there is essentially no physical / chemical stress on the second material.

[0047] In an embodiment, the second material may include material at any site on the lithographic object and also material in the processing area. As second material, any material that may in principle be subjected to the material removal effect of the method is also considered. This may include, for example, exposure of the second material to a first (or second) gas during the method and / or presence in a relatively close (otherwise intimate) environment of the electron beam. For example, the second material may be adjacent to the first material or mechanically coupled to the first material (including indirectly, for example, via an intervening material). In this case, removal of the first material is considered to be associated with exposure of the surface of the second material, such that the second material becomes subject to the material removal effect of the method. According to the invention, removal of the second material can be counterbalanced via the selectivity of the method. The second material may be, for example, part of a layer of the object adjacent (directly or indirectly) to the first material in a typical application of the method. For example, the object may have a characteristic layer structure in which a cap layer is adjacent to a reflective layer stack (e.g., a Bragg mirror). The characteristic layer structure may include a buffer layer adjacent to the cap layer. Additionally, there may be an absorbing layer adjacent to the buffer layer. In one embodiment, a portion of the absorbing layer may include a first material (to be removed) in the method. The method may thus be configured with selectivity such that the second material includes the material of the buffer layer, the material of the cap layer, and / or the material of the reflective layer stack. In one embodiment, the selectivity is configured such that the second material explicitly includes the material of the cap layer of the reflective layer stack of the object. This may allow a controlled end of the method through a reduced removal rate of the cap layer without attacking the reflective layer stack. The cap layer may thus act as a removal stop (e.g., an etch stop), thus avoiding damage to the reflective layer stack that may be associated with damage to the optical properties of the object.

[0048] The method may be performed such that the selectivity for removal of the first material relative to the second material is at least 2: 1. In one embodiment, the selectivity for removal of the first material relative to the second material is at least 15: 1, preferably at least 25: 1, and most preferably at least 50: 1.

[0049] In one embodiment, in the method of the first aspect, the method further comprises removing at least one intermediate material disposed between the first material and the second material. As described herein with respect to the characteristic layer structure, the intermediate material may, for example, comprise a portion of the buffer layer of the object. It is further contemplated that the at least one intermediate material may comprise a portion of the buffer layer and a portion of the cap layer of the object. In particular, the intermediate material (to be removed) may comprise a portion of a layer between the first material and a material of the reflective layer stack of the object. For example, the characteristic layer structure may not necessarily comprise a cap layer or a buffer layer between the absorbing layer and the reflective layer stack. For example, other types of intermediate materials (e.g., having other functions) may be present between the absorbing layer and the reflective layer stack.

[0050] The intermediate material of the lithographic object may, for example, include the properties of the first (or second) material described herein, however, the intermediate material (to be removed) does not necessarily have to include the properties of the first material (or the second material) specified herein.

[0051] In embodiments, the intermediate material may include tantalum. In such embodiments, the intermediate material may be considered a tantalum-based material. For example, the intermediate material may include a tantalum compound (or may consist essentially of tantalum).

[0052] For example, the intermediate material may include tantalum and one or more of the following: oxygen, nitrogen, carbon, boron, hydrogen. For example, the intermediate material may include tantalum and boron. For example, the intermediate material may include tantalum and nitrogen. For example, the intermediate material may include tantalum and oxygen. For example, the intermediate material may include tantalum, oxygen, and boron.

[0053] In embodiments, the portion of tantalum in the intermediate material may comprise at least 50 atomic percent or more. In embodiments, the portion of tantalum in the intermediate material may comprise at least 70 atomic percent or more. For example, the portion of tantalum in the intermediate material may be less than 95 atomic percent. For example, the portion of tantalum in the intermediate material may be between 50 atomic percent and 95 atomic percent.

[0054] For example, the intermediate material may include at least one of the following: TaBO, TaO, TaON, TaN, TaBN.

[0055] In an embodiment of the method, the method may include providing a third gas including a third molecule, and the removal of the intermediate material is based at least in part on the third gas (and the provided particle beam). In an embodiment, the third gas may be considered a primary etch gas for removing the intermediate material (as similarly described herein with respect to the first gas).

[0056] The features described herein for a first gas (or a first molecule), for example, may be similarly applied to a third gas (or a third molecule).

[0057] In embodiments, the first material and the intermediate material may be removed in a sequential manner (eg, in a process including at least two steps).

[0058] For example, the method may include that in a first step, a first material is removed (as described herein). In that regard, a first gas, or a first gas in combination with a second gas, may be provided. In the first step, the intermediate material may, for example, function as a removal stop (e.g., an etch stop) for the removal of the first material.

[0059] Subsequently, in a further step, the intermediate material may be removed by a third gas (as described herein). In that regard, the already provided first gas (or the first gas and the second gas) may no longer be provided. For example, it may be considered that the already provided first gas (or the already provided first and second gases) may be pumped away from the vicinity of the intermediate material. It may be considered that a waiting time is performed between the removal of the first material and the removal of the intermediate material. This may allow (substantially) the first gas (or the first and second gases) to be not present in the region of the particle beam-induced reaction at a high concentration (e.g., compared to the concentration during the first step).

[0060] In an embodiment, the method may further include providing a fourth gas comprising a fourth molecule, and the removal of the intermediate material is further based at least in part on the fourth gas. The fourth gas described herein may be considered an additive gas to the third gas (as similarly described herein with respect to the second gas).

[0061] The features described herein for the second gas (or second molecule) may, for example, be correspondingly applied to the fourth gas (or fourth molecule) as well.

[0062] In an embodiment of the removal of the first material and the intermediate material, the first molecule of the first gas provided to remove the first material may include chlorine. The third molecule of the third gas provided to remove the intermediate material may include fluorine in that embodiment. Thus, the first material may be treated with a chlorine-based chemistry, whereas the intermediate material may be treated with a fluorine-based chemistry. In such an embodiment, the first molecule may include, for example, nitrosyl chloride (NOCl) and / or nitrile chloride (ClNO2). In such an embodiment, the third molecule may include, for example, xenon difluoride (XeF2).

[0063] In an embodiment of removing a first material and an intermediate material, a first molecule of the provided first gas may include NOCl and a second molecule of the provided second gas may include water (H2O) to remove the first material. In that embodiment, a third molecule of the provided third gas may include XeF2 and a fourth molecule of the provided fourth gas may include water. Thus, the first material may be removed with NOCl and H2O and the intermediate material may be removed with XeF2 and H2O.

[0064] In a further example of removing the first material and the intermediate material, the first gas may include NOCl, the second gas may include water (H2O) to remove the first material, the third gas may include XeF2, and the fourth gas may include water and nitrogen dioxide (NO2).

[0065] In embodiments, the cap layer described herein may include ruthenium. In such embodiments, the cap layer material may be considered a ruthenium-based cap layer. For example, the cap layer may consist (substantially) of ruthenium. For example, the cap layer may include a ruthenium compound. For example, the cap layer may include ruthenium and at least one of the following: Ti, Nb, Mo, Zr, Y, B, La, Co, Re (the cap layer may further include nitrogen).

[0066] In one embodiment, in the method of the first aspect, the method further comprises removing at least a surface material of the object. The surface material may include, for example, a material of the object having a surface (e.g., an exposed surface of the object) that is contactable with the first gas and / or the second gas, and with the particle beam. The surface material may include any material and is not limited to the substances and substance ratios of the first and second materials as specified herein. The surface material may be removed now, for example, for the method according to the invention, to expose the first material disposed thereunder. With respect to the characteristic layer structure of the object described herein, the surface material may be, for example, a portion of the surface layer adjacent to the absorbing layer (e.g., to the buffer layer). The surface layer in this embodiment may include an anti-reflection layer, an oxide layer, a passivation layer.

[0067] In one embodiment, in the method of the first aspect, the particle beam is at least partially based on an acceleration voltage of less than 3 kV, preferably less than 1 kV, more preferably less than 0.6 kV. These ranges of acceleration voltages are advantageously capable of removing the first material (as described herein).

[0068] It is further contemplated that the particle beam may be based on an acceleration voltage of less than 30 kV, preferably less than 20 kV. In one embodiment, an acceleration voltage between 3 kV and 30 kV may be used for imaging purposes in the process (e.g., for imaging before or after ablation and / or imaging during ablation).

[0069] In one embodiment, the particle beam comprises a current between 1 pA and 100 pA, preferably between 5 pA and 80 pA, and most preferably between 10 pA and 60 pA.

[0070] In an embodiment, the particle beam may include a current between 50pA and 100pA. For example, the particle beam may include a current between 60pA and 100pA, 70pA and 100pA, 80pA and 100pA, or 90pA and 100pA.

[0071] In further embodiments, the particle beam may include a current between 100pA and 200pA. For example, the particle beam may include a current between 110pA and 200pA, 120pA and 200pA, 130pA and 200pA, or 150pA and 200pA.

[0072] For example, the particle beam may include a current between 100 pA and 300 pA. For example, the particle beam may include a current between 110 pA and 300 pA, 150 pA and 300 pA, 200 pA and 300 pA, or 250 pA and 300 pA.

[0073] In one embodiment, in the method of the first aspect, the method further comprises determining an end point of the removal based at least in part on the detection of electrons emitted from the object. For example, the electrons may be emitted thanks to an interaction of the delivered particle beam with the object material or with the processing area material. These may be electrons caused by the particle beam that leave the area of ​​operation of the particle beam incident on the material for physical reasons. In one embodiment, the electrons include scattered electrons and / or secondary electrons. The scattered electrons may include, for example, electrons backscattered by the object (backscattered electrons, i.e., BSE) and / or electrons forward scattered by the object (forward scattered electrons, i.e., FSE). The detected electrons may provide information about the material properties in the area of ​​operation of the particle beam, making it possible to complete the material processed by the particle beam. For example, the determination of the end point may include using the detected electrons to ensure that the particle beam is not / no longer acting on the first material. This may indicate that the first material has been removed and that the end point of the process (i.e., the end of the process) has been reached. Additionally, the endpoint determination may include using the detected electrons to ensure that the particle beam is processing a second material (not selectively removed) and that the endpoint of the process has been reached. In principle, the detected electrons can be used to determine the material currently being processed by the particle beam without being based on an endpoint determination (e.g., for process monitoring, as a process history protocol, etc.). The particle beam may be configured such that there is a sufficient difference in the signal of the detected electrons (e.g., via accelerating voltage, current, etc.) depending on the material in the operating region.

[0074] In one embodiment, in the method of the first aspect, the particle beam comprises an electron beam. For example, the removal described herein may comprise, in the context of the method, electron beam induced etching (e.g., also known as (F)EBIE - (focused) electron beam induced etching).

[0075] However, it is contemplated that the particle beam may also include an ion beam (e.g., gallium ions, helium ions, etc.). For example, the removal of the first material may be based on ion beam induced machining / etching (e.g., focused ion beam (FIB) milling).

[0076] Furthermore, the use of multiple particle beams as the particle beam is also conceivable.

[0077] In one embodiment, the method is carried out such that the sidewall angle of the first material is between 70° and 90°, preferably between 74° and 90°, more preferably between 78° and 90°, most preferably between 80° and 90°. The sidewall angle may for example be relative to the plane of a layer deposited below the first material or may be relative to an otherwise (flat) plane of the object.

[0078] In one embodiment the method is carried out such that the surface of the second material has a roughness square, RMS, of less than 3 nm, preferably less than 2 nm, more preferably less than 1 nm, most preferably less than 0.5 nm.

[0079] In one embodiment, the method of the first aspect is performed such that a defect in the object is repaired. For example, the method may include repairing an opacity defect in the object.

[0080] Here, an opaque defect is a defect site on a lithography object that should not actually be opaque, i.e., transparent (e.g., designed to be transmissive or have no specific absorption for radiation of a particular wavelength, e.g., lithography wavelength), according to the design of the object. In contrast, a transparent defect is a defect site on an object for lithography that should actually be opaque (e.g., non-transmissive or strongly absorbing radiation of a particular wavelength, e.g., lithography wavelength), according to the design of the object. In particular, opacity may be defined in relation to the lithography method for the object. For example, an object for lithography may include an EUV mask for an EUV lithography method, in which case "opaque" may refer to a lithography wavelength of 13.5 nanometers. "Opaque" may also relate to a DUV lithography method (e.g., at a lithography wavelength of 193 nanometers or 248 nanometers), an i-line lithography method (e.g., at a lithography wavelength of 265 nanometers), or any other lithography method, depending on the object. Additionally, the opaque defect may include, for example, a defect site having opaque material of a layer of a lithography mask (e.g., this may include a layer designed as a layer for an opaque pattern element of the object), where the method may include removing the first material such that the defect site is no longer opaque.

[0081] For example, repairing the defect may include first locating the defect (e.g., via a scanning electron microscope, optical microscope, etc.). Here, a processing area used for removing the first material may be defined based on at least one characteristic of the located defect (e.g., the position, shape, size, type, etc. of the defect). Correcting the defect in the object may further include generating a repair shape that encompasses the defect. In one embodiment, the repair shape may serve as a processing area in the methods specified herein. The repair shape may have, for example, a pixel pattern that may enable locating the defect site. The pixel pattern may be designed, for example, to follow the contour of the defect, such that all pixels in the pixel pattern will essentially fall within a site within the defect and thus constitute a defective pixel. In another embodiment, the pixel pattern has a fixed geometric shape (e.g., a polygon, a rectangle, a circle, etc.) that completely encompasses the defect, in which case not all pixels necessarily constitute the defect site. Here, the pixel pattern may include defective pixels that fall within the defect site and non-defective pixels that fall within sites that do not cover any portion of the defect. In one embodiment, the method includes directing a particle beam onto at least defective pixels of a pixel pattern of the repair shape during the generation of the material. Further, the particle beam may be configured to be directed onto any defective pixels during the removal of the first material. This can ensure that the removal of the first material is locally restricted to the defective pixels, and thus only the defects are treated.

[0082] In a further embodiment, the method may be used in the treatment of an object, including local generation of a material. The treatment and local generation of a material may be performed, for example, in the context of defect treatment of the object (e.g., in the repair of transparent defects and / or defect sites, in the removal of particles, etc.). Thus, the first material does not necessarily have to be a layer material of the object. The generation of a material may, for example, include the deposition of a material that corresponds to the nature of a first material (as described herein). For example, in the course of local generation of a material, there may be an inappropriate generation of a first material. Thus, with the method according to the invention, an inappropriately generated material may be removed as a first material (as described herein). For example, in the course of a complex repair, it may also be necessary to specifically generate a first material and to remove it in a controlled manner (for example, this may be necessary if the first material is generated as a sacrificial layer).

[0083] In one embodiment, in the method of the first aspect, the object includes an EUV mask and / or a DUV mask, for example, the characteristic layer structure described herein corresponds to the layer structure of an EUV mask.

[0084] A second aspect relates to an apparatus for processing an object for lithography, comprising a means for providing a first gas, a means for providing a particle beam to a processing area of ​​the object, and configured to perform the method of the first aspect. The apparatus may further comprise a means for executing a computer program (e.g., a computer system, a computing device, etc.). The apparatus may essentially correspond to a scanning electron microscope capable of providing an electron beam as a particle beam to the object. The scanning electron microscope may be configured to provide the gases described herein. The first gas (and / or the second gas) may be stored, for example, in a corresponding reservoir tank and may be guided into the processing area of ​​the object via a gas supply system (e.g., a gas conduit with a gas nozzle).

[0085] The third aspect relates to a lithographic object processed by the method of the first aspect. Here, it is possible to detect whether the object has been processed by the method of the first aspect, for example via optical analysis of the object. For example, for a lithographic object, an optical analysis may be performed or undertaken initially (e.g., after the creation of the object and / or in case of the introduction of the object into a semiconductor workpiece, for example in the course of defect qualification of the object). The optical analysis may be based, for example, on an optical or particle-based microscope (e.g., a mask metrology apparatus, a mask microscope), and for example on an imaging operation. In the processing of the object in one embodiment of the first aspect, after the initial analysis, the first material may have been removed as described herein. The removal of the first material may be detected via a repeated visual analysis (e.g., in the course of a repair check or another defect qualification). The detection may be performed, for example, via a comparison of the initial visual analysis with the repeated visual analysis (e.g., via a comparison of corresponding images). Furthermore, detection in the method may be based on material analysis of the object (eg Auger spectroscopy, x-ray spectroscopy, etc.), which is performed, for example, as a complementary technique to the initial or repeated visual analysis.

[0086] A fourth aspect relates to a method for processing a semiconductor-based wafer. The method of the fourth aspect further comprises lithographic transfer of a pattern associated with a lithographic object onto the wafer, the object having been processed according to one of the embodiments of the first aspect of the invention provided herein. The lithographic transfer may comprise a lithographic method for which the object is designed (e.g. EUV lithography, DUV lithography, i-line lithography, etc.). For example, the method of the fourth aspect may comprise providing a source of electromagnetic radiation (e.g. EUV radiation, DUV radiation, i-line radiation, etc.). This may additionally comprise providing a developable lacquer layer on the wafer. The lithographic transfer may be based at least in part on a radiation source and on providing a developable lacquer layer. Here, for example, it is possible to image a pattern (in a transferred form) onto the lacquer layer using radiation from the radiation source.

[0087] The methods described herein may be recorded, for example, in a documented form. This may be realized, for example, with a digital file, analogically (e.g., in paper form), in a user handbook, in a formula (e.g., recorded on a device and / or computer in a semiconductor fab). It is also contemplated that a documented protocol may be compiled in the performance of one of the methods described herein. The protocol may, for example, be capable of certifying the performance of the method and its details (e.g., formulas) at a later time (e.g., during a defect evaluation, material review board, audit, etc.). The protocol may include, for example, a protocol file (i.e., a log file), which may, for example, be recorded on a device and / or computer.

[0088] A fifth aspect relates to a computer program comprising instructions which, when executed by a computer system, cause the computer system to perform the method according to the first aspect and / or the method according to the fourth aspect.

[0089] A further aspect relates to the aforementioned device, with a memory that contains a computer program. The device may further comprise means for executing the computer program. Alternatively, the computer program may be stored elsewhere (e.g. in the cloud), and the device may simply comprise means for receiving instructions resulting from the execution of the program elsewhere. In any case, this may for example make the method to be performed in an automated or autonomous manner in the device. As a result, for example, the intervention by an operator may be minimized, thus minimizing both costs and complexity when processing masks.

[0090] The features of the methods specified herein (also examples) may also be applied or applicable to the mentioned apparatus and to the mentioned objects accordingly. Similarly, the features specified herein of the apparatus specified herein (also examples) and the features of the mentioned objects also specified herein (also examples) may also be applied or applicable to the methods described herein accordingly.

[0091] The following detailed description provides technical background and examples of the invention with reference to the figures shown below. [Brief description of the drawings]

[0092] [Figure 1] 1 presents a schematic diagram of an exemplary repair situation for a prior art lithographic object in a top view. [Diagram 2] 1 shows a schematic diagram of an exemplary method of the present invention. [Figure 3a-3c] 3a-c provide, by way of example, schematic illustrations of operations in the method of the invention in cross-section. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0093] FIG. 1 presents a schematic diagram of a top view of an exemplary repair situation for a lithography object. The lithography object may include a lithography mask suitable for any lithography method (e.g., EUV lithography, DUV lithography, i-line lithography, nanoimprint lithography, etc.). In an embodiment, the lithography mask may include an EUV mask, a DUV mask, an i-line lithography mask, and / or a nanoimprint stamp. Furthermore, the lithography object may include a binary mask (e.g., a chrome mask, an OMOG mask), a phase mask (e.g., a chrome-free phase mask, an alternating phase mask (e.g., a rim phase mask)), a half-tone phase mask, a tri-tone phase mask, and / or a reticle (e.g., with a pellicle). The lithography mask may be used in a lithography method, for example, for manufacturing semiconductor chips.

[0094] Lithographic objects may contain (undesirable) defects. For example, defects may be caused in the production of the object. Furthermore, defects may be caused in the (lithographic) processing of the object, deviations in the (lithographic) processing process, transportation of the object, etc. Therefore, due to the usually expensive and complex production of lithographic objects, defects are usually repaired.

[0095] In the embodiments described herein, for purposes of illustration, an EUV mask is frequently used as an example of a lithographic object, however, any object for lithography that is not an EUV mask (e.g., as described herein) is contemplated.

[0096] FIG. 1 can show, in schematic form, in a top view, two local states D, R of a detail 1000 of an EUV mask in the process of repairing a defect of the mask. The detail 1000 shows a portion of a pattern element PE of the EUV mask. The pattern element PE may be considered as a pattern element of the EUV mask. The pattern element PE may be a portion of a designed pattern that can be transferred to a wafer, for example, via a lithographic method. Local state D shows an opaque defect 1010 adjacent to the pattern element PE. The opaque defect 1010 may be characterized, for example, by an excess (opaque) material that should not be present at the defect site according to the mask design. The excess (opaque) material may, for example, correspond to an opaque material of the pattern element PE, or else to any other material (as described herein) of the layer of the pattern element PE. With respect to FIG. 1 (state D), it is clear that a defect-free pattern element PE in the detail 1000 must have a square shape, and this target state does not exist as a result of the opaque defect 1010. The repair procedure RV thus removes excess (opaque) material, typically in the area of ​​the opaque defect 1010, so as to create a repaired state R of the pattern element PE. In this way, state R indicates that the opaque effect is no longer caused in the original defect area 1020 (i.e., at the original site of the opaque defect) and that no excess (opaque) material is present any more. The removal of the defect 1010 thus re-establishes the target rectangular state of the pattern element PE after the repair operation.

[0097] During use in a lithographic apparatus or lithographic method, a lithographic mask may be subjected to extreme physical and chemical environmental conditions. This is especially true for exposure of an EUV mask (and also a DUV mask or other masks described herein) during a corresponding lithographic method, where the opaque material of the pattern element PE may be exposed to these effects to a significant extent. For example, in the case of EUV exposure, a hydrogen plasma containing free hydrogen radicals may be released, which may attack, among other materials, the opaque material of the pattern element PE, causing material modification and / or removal effects. Further damaging effects may occur in EUV lithography and mask cleaning processes. Damage to the mask material includes chemical and physical changes of the material, for example due to (EUV) radiation, temperature, and also reactions with hydrogen or other reactive hydrogen species (e.g., free radicals, ions, plasma, etc.). Material changes may also be caused by reactions with the purge gas (e.g., N2, extremely clean dry air - XCDA®, noble gases, etc.) in conjunction with the exposure radiation (e.g., EUV radiation, DUV radiation). Damage to the material may also result or be enhanced by downstream processes (e.g., mask cleaning operations). Downstream processes may further attack the opaque material of the pattern element PE that has already been damaged by chemical / physical reactions, for example during the exposure operation, thus exacerbating the damage.

[0098] In general, therefore, the material properties of the EUV mask, and in particular the opaque material of the EUV mask (or of the pattern element PE), are therefore designed to withstand the aggressive physical / chemical conditions in lithography, in order to in particular counteract material removal effects. The particular opaque material used here in the pattern element PE may be a chemically resistant material. In particular, as resistant material of the EUV mask, it is possible to use chromium nitride-containing materials and also chromium-containing materials (as described herein) with a high nitrogen content due to their very high chemical stability. Chromium nitride-containing materials can be, for example, Cr a Nb Z c (a, b>0, c≧0, Z: one or more other elements), where Z may include metals, nonmetals, metalloids, and alkali metals (e.g., Li, Na, K, Rb, Cs). Furthermore, Z may include alkaline earth metals (e.g., Be, Mg, Ca, Sr, Ba), group 3 main group elements (e.g., B, Al, Ga, In, Tl), group 4 main group elements (e.g., C, Si, Ge, Sn, Pb), and group 5 main group elements (e.g., N, P, As, Sb, Bi). Additionally, Z may include chalcogenides (e.g., O, S, Se, Te), halogens (e.g., F, Cl, Br, I), noble gases (atoms) (e.g., He, Ne, Ar, Kr, Xe), and transition elements (e.g., Ti, Hr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg).

[0099] However, this type of resistant (opaque) material of the pattern element PE or of the EUV mask may make the repair operation RV of the opaque defect 1010 significantly more difficult, since the repair operation consists in specifically removing the resistant (opaque) material. In particular, this situation may make it more difficult to repair the mask using an electron beam induced etching process.

[0100] 2 shows a schematic diagram of an exemplary method 200 of the present invention. The method 200 may be used to remove material from an EUV mask. In particular, the method 200 may be used to remove material from an opaque defect 1010 during a repair operation.

[0101] The method 200 may include providing a first gas including a first molecule. The first gas may include, for example, NOCl and / or XeF2 as the first molecule. Still other gases are contemplated as first gases as described herein.

[0102] Other molecules are suitable as the first molecule of the first gas for method 200. For example, the first molecule may include a molecule that can be considered an acid halide of a nitrogen-containing (e.g., inorganic) acid. The first molecule may also include a molecule that can split into chlorine radicals and nitric oxide under appropriate reaction conditions, and / or in addition, for example, into further non-polar species. Additionally, the first molecule may include a molecule that, in aqueous solution, provides at least one of the following molecules: NO, HCl, HNO2, HNO3.

[0103] The method 200 may further include providing 220 a particle beam to the processing region of the object to remove a first material in the processing region based at least in part on the first gas. The first material may include chromium and nitrogen here. A feature 230 of the method 200 may be that the first material includes at least 5 atomic percent nitrogen, preferably at least 10 atomic percent nitrogen, particularly preferably at least 20 atomic percent nitrogen. The method 200 may include an electron beam as the particle beam, such that electron beam induced etching of the first material by the method 200 may be possible.

[0104] Here, the first material may particularly apply to a resistant (opaque) material of an EUV mask (as described herein) that is to be removed in the course of repairing the opaque defect.

[0105] The method 200 may include providing a second gas as an additive gas to aid in the etching process (e.g., with respect to selectivity, etch rate, anisotropy factor, etc.). In particular for electron beam induced etching, the first gas used in the method 200 may be NOCl and additive gas H2O (i.e., water (vapor)). Similarly, it is contemplated that in the case of electron beam induced etching, the first gas used in the method 200 may be XeF2 and additive gas H2O (i.e., water (vapor)). Furthermore, the second molecule may include a dipole moment between 1.6D and 2.1D, preferably between 1.7D and 2D, more preferably between 1.8D and 1.95D, and most preferably between 1.82D and 1.9D. Similarly, it is contemplated that the second molecule includes at least one oxygen atom and is free of nitrogen atoms. Furthermore, the second molecule may include a molecule that, upon reaction with NOCl, provides at least one of the following molecules: NO, HCl, HNO2, HNO3.

[0106] 3a-b present schematic illustrations, in cross section, of steps of a method 200 that can be effected in the course of repairing a defect in a lithographic object, by way of example.

[0107] 3a provides in schematic form an exemplary characteristic layer structure of a reflective lithography mask for the EUV wavelength region (i.e., an EUV mask). The exemplary EUV mask may be designed for an exposure wavelength in the region of 13.5 nm, for example. The EUV mask may include a substrate S made of a material with a low thermal expansion coefficient, for example, quartz. Other dielectric, glass, or semiconductor materials may be used as substrates for EUV masks as well.

[0108] The substrate S may be adjacent to a deposited multilayer film or reflective layer stack ML, for example including 20-80 pairs of alternating molybdenum (Mo) and silicon (Si) layers, also referred to as MoSi layers. The individual layers of the multilayer film ML may have different refractive indices, resulting in a Bragg mirror capable of reflecting incident radiation (e.g., EUV radiation).

[0109] To protect the reflective layer stack ML, a cap layer D may be applied, for example, on the top layer of the reflective layer stack ML. The cap layer D may protect the reflective layer stack ML from damage due to chemical processes during the production and / or use of the EUV mask (e.g., during a lithography process). The cap layer D may also include ruthenium and an element or compound of an element that increases the reflectivity by 3% or less at a wavelength of 13.5 nm. Additionally, the cap layer D may also include Rh, Si, Mo, Ti, TiO, TiO2, ruthenium oxide, niobium oxide, RuW, RuMo, RuNb, Cr, Ta, nitrides, and compounds and combinations of the aforementioned materials.

[0110] On the cap layer D, there may be several layers, which may include, for example, a layer of pattern elements (i.e., a pattern element layer). The pattern element layer may include a buffer layer P, an absorbing layer A, and / or a surface layer O. The properties of the pattern element layer (e.g., the inherent material properties of the pattern element layer, the layer thickness of the pattern element layer, etc.) and the geometry of the pattern element PE formed therefrom may be designed to cause an opaque effect for the exposure wavelength of the EUV mask. For example, the pattern element PE may be designed to be opaque (i.e., non-transmissive or highly absorbing) for radiation of light having a wavelength of 13.5 nm. The pattern element layer may correspond to a layer of the opaque defect 1010, but the opaque defect 1010 does not necessarily require all the pattern element layers. For example, the opaque defect 1010 may simply have a buffer layer P and an absorbing layer A.

[0111] A buffer layer P may be present on the cap layer D. An absorbing layer A may also be present on the buffer layer P. The absorbing layer A may be designed to be effective in absorbing radiation at lithographic wavelengths (as described herein). The absorbing layer A may therefore be the main contributor to the opacity effect of the pattern element (or of the opaque defect 1010). The optical properties of the absorbing layer A may be described, for example, by a birefringence, which may include a phase shift contribution (i.e., n) and an absorption contribution (i.e., k). For example, n and k may be considered as intrinsic material properties of the absorbing layer. Only certain chemical elements and / or compounds of chemical elements have phase shift and / or absorption properties that are favorable for the relevant lithography method (e.g., EUV lithography method). FIG. 3a shows the layer thickness of the absorbing layer A by way of example. The layer thickness of the absorbing layer A (and also the layer thicknesses of the other layers of the mask) is ascertained, for example, along a normal vector to the plane of the mask. Furthermore, a surface layer O may be present on the absorbing layer A. The surface layer O may include an anti-reflection layer, an oxidation layer, and / or a passivation layer. Similar to the absorption layer A, the buffer layer P and / or the surface layer O may also contribute to the absorption and opacity effect of the pattern elements PE or of the opaque defects 1010.

[0112] In principle, any of the pattern element layers described herein may comprise the mentioned resistant material (i.e. chromium nitride or chromium with a high nitrogen content). Typically, for example, the absorber layer A comprises chromium with a (high) chromium nitride content or with a high nitrogen content. However, in addition, it is also possible, for example, for the buffer layer to have a (high) chromium nitride content or with a high nitrogen content.

[0113] Thus, the first material of method 200 may include the material of any pattern element layer. In particular, the first material of method 200 may include the material of absorber layer A.

[0114] FIG. 3b shows the result of an exemplary method 300 for removing a portion of the absorbing layer A. The absorbing layer A is designed as the first material in the method 200. First, a portion of the surface layer O may be removed first. For example, this can be performed similarly to the method 200 via electron beam induced etching in a separate step. The surface layer does not necessarily need to be removed with a first and / or second gas (as described herein). It is also conceivable that the electron beam induced etching is exclusively designed to remove the surface layer (e.g., with an etching gas that matches the material of the surface layer). After the surface layer O is removed, it is then possible to remove a portion of the absorbing layer A as the first material of the method 200 (e.g., to repair opaque defects). FIG. 3b shows a selective electron beam induced etching of the absorbing layer A with respect to the buffer layer P. The method 200 may therefore be adjusted such that the etching rate of the absorbing layer A is increased compared to the etching rate of the buffer layer P. For example, the etch selectivity can be adjusted via the properties of the second gas in method 200 (e.g., via an appropriate selection of the second gas (e.g., water) or via a gas flow rate of the second gas). Additionally, the etch selectivity can also be adjusted by the properties of the first gas (e.g., via a selection of the first gas (e.g., NOCl or XeF2) or via a gas flow rate of the first gas). In this embodiment, the buffer layer P accordingly functions as an etch stop via a selected etch selectivity.

[0115] FIG. 3c shows a further result of the exemplary method 200 for removing a portion of the absorbing layer A. First, it is now possible to remove a portion of the surface layer O (as described herein). After the surface layer O is removed, it is then possible to remove a portion of the absorbing layer A as a first material of the method 200. It is now also possible to etch a portion of the buffer layer P as an intermediate material. The method 200 may thus be adjusted to increase the etch rate of the absorbing layer A and also the etch rate of the buffer layer P compared to the etch rate of the cap layer D. The etch rate of the absorbing layer A may be of the same order of magnitude as the etch rate of the buffer layer P. The etch selectivity may be adjusted as described herein. As shown in FIG. 3c, this may realize a selective electron beam induced etching of the absorbing layer A and of the buffer layer P relative to the cap layer D. In this embodiment, the cap layer D thus acts as an etch stop via a chosen etch selectivity.

[0116] In one embodiment, the surface layer O is not removed separately, but rather is removed via the same process used for the localized removal of the absorbing layer A (or the absorbing layer A and the buffer layer P) in method 200 .

[0117] In an embodiment, the characteristic layer structure may include a ruthenium-based cap layer D (as described herein) and a tantalum-based buffer layer P. In this embodiment, the characteristic layer structure may further include an absorber layer A (as described herein), which may include a first material (as described herein). In such an embodiment, the absorber layer A may include, for example, chromium and at least 1 atomic percent nitrogen (e.g., chromium nitride), the buffer layer P may include tantalum, and the cap layer D may include ruthenium. This exemplary characteristic layer structure may be sequentially processed (e.g., via two or more sub-processes) in a manner described herein, for example.

[0118] For example, in a first step, the absorbing layer A may be locally removed in an e-beam induced process in which NOCl is supplied as the main etching gas and H2O is supplied as the additive gas. For example, the etching rate of this sub-process may be adapted such that the absorbing layer A is etched at a faster etching rate than the buffer layer P. The buffer layer P may thus function as an etching stop for this sub-process, and this buffer layer P may not be (substantially) removed during the first sub-process. Subsequently, the (tantalum-containing) buffer layer P may be locally removed in an e-beam induced process in which XeF2 is supplied as the main etching gas and NO2 and H2O are supplied (together) as additive gases. For example, the etching rate of this sub-process may be adapted such that the buffer layer P is etched at a faster etching rate than the cap layer D. The cap layer D may thus function as an etching stop for this sub-process, and this cap layer D may not be (substantially) removed during this sub-process.

[0119] In principle, in a mask repair, it may be necessary to generate or deposit a material (as a repair material). (For example, Cr, as described herein. a N b Z c In the case of mask repair using electron beam induced deposition of chromium nitride (in the form of chromium oxide or other chromium-containing deposits), chromium oxide or other chromium-containing deposits may also result in undesired material deposition. Undesired material deposition may be caused, for example, by off-target strands of the electron beam and secondary electrons generated thereby. Furthermore, undesired deposition (of repair material) may also be caused by secondary electrons generated at sites adjacent to the repaired defect and by secondary electrons that escape at the vertical edge of the processed material and propagate to sites adjacent to the repaired defect. Similarly, forward scattered electrons (FSE), which escape from the sides of the existing material, and backscattered electrons (BSE), which escape from the surface in the environment of the repaired site, can contribute to unwanted material deposition.

[0120] Thus, a further application of method 200 is the removal of material deposited by these mentioned mechanisms on areas adjacent to the repaired defect. Thus, in one embodiment, method 200 also includes the generation of repair material.

[0121] In the process of producing the repair material, a deposition gas can be used in the electron beam induced deposition. Here, at least one of the following can be included as a deposition gas in the present invention: (metals, transition elements, typical elements) alkyl, such as cyclopentadienyl (Cp) or methylcyclopentadienyl (MeCp), trimethylplatinum (CpPtMe3 or MeCpPtMe3), tetramethyltin SnMe4, trimethylgallium GaMe3, ferrocene Cp2Fe, bisarylchromium Ar2Cr, and other compounds of this type. In addition, at least one of the following may be included as a first gas in the present invention: (metals, transition elements, typical elements) carbonyl, such as 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 , iron pentacarbonyl Fe(CO)5, and other compounds of this type. Additionally, one of the following may be included in the present invention as the first gas: (metal, transition element, main group element) alkoxides, such as tetraethoxysilane Si(OC2H5)4, tetraisopropoxytitanium Ti(OC3H7)4, and other compounds of this type.

[0122] At least one of the following may be included as a deposition gas in the present invention: (metal, transition element, main group element) halides, such as WF6, WCl6, TiCl6, BCl3, SiCl4, and other compounds of this type. In addition, at least one of the following may be included as a deposition gas in the present invention: (metal, transition element, main group element) complexes, such as copper bis(hexafluoroacetylacetonate) Cu(C5F6HO2)2, dimethyl gold trifluoroacetylacetonate Me2Au(C5F3H4O2), and other compounds of this type. At least one of the following may be included as a deposition gas in the present invention: CO, CO2, organic compounds such as aliphatic or aromatic hydrocarbons, components of vacuum pump oil, volatile organic compounds, and other such compounds.

[0123] The method 200 (or the method of the first aspect) may be performed via an apparatus of the invention as described herein. In one embodiment, the apparatus comprises a mask repair apparatus for repairing or processing lithographic masks. The apparatus may be used to locate and repair or improve mask defects. The apparatus may include parts such as the apparatus described in US Patent Application Publication No. 2020 / 103751 (see corresponding FIG. 3A therein). The apparatus may be part of, for example, a computer system, for example including a control unit. The apparatus may be configured in one embodiment such that the computer system and / or the control unit control the process parameters of the method in the first aspect disclosed herein. This configuration may enable a controlled and also automated implementation of the method according to the invention as specified herein, for example without manual intervention. This configuration of the apparatus may be realized or enabled, for example, via a computer program according to the invention as described herein.

Claims

1. 1. A method of processing an object for lithography, comprising the steps of: Providing a first gas comprising a first molecule; providing a particle beam to the processing area of ​​the object to remove a first material (A) in the processing area based at least in part on the first gas; Including, the first material comprises chromium and nitrogen; The first material comprises at least 1 atomic percent nitrogen, preferably at least 5 atomic percent nitrogen, more preferably at least 10 atomic percent nitrogen, and particularly preferably at least 20 atomic percent nitrogen; method.

2. The method of claim 1 , wherein the first material is capable of absorbing radiation associated with the object.

3. The method according to claim 1 or 2, wherein the first material corresponds to a layer material of a pattern element (PE) of the object.

4. The method of any of claims 1 to 3, wherein the first material comprises chromium nitride.

5. The method of any one of claims 1 to 4, wherein the first molecule comprises at least one halogen atom.

6. The method of any one of claims 1 to 5, wherein the first molecule comprises a halogen compound.

7. The method of claim 6, wherein the halogen compound comprises a nitrosyl halide and / or a nitrile halide.

8. and / or the nitrosyl halide comprises at least one of the following: nitrosyl chloride, NOCl, nitrosyl fluoride, NOF, nitrosyl bromide, NOBr; and / or The nitrile halide is selected from the group consisting of nitrile chloride, ClNO 2 , fluoronitrile, FNO 2 At least one of the following is included: The method of claim 7.

9. The method of claim 6 , wherein the halogen compound comprises a noble gas halide.

10. The noble gas halide is selected from the group consisting of xenon difluoride, XeF 2 , xenon dichloride, XeCl 2 , xenon tetrafluoride, XeF 4 , xenon hexafluoride, XeF 6 The method of claim 9, comprising at least one of:

11. The method of claim 6 , wherein the halogen compound comprises an interhalogen compound.

12. The method of any of claims 1 to 11, wherein a first dipole moment associated with the first molecule comprises at least 1D, preferably at least 1.5D, more preferably at least 1.7D, and most preferably at least 1.8D.

13. The method further comprises:

13. The method of any of claims 1 to 12, comprising providing a second gas comprising second molecules, and wherein removal of the first material is further based, at least in part, on the second gas.

14. 14. The method of claim 13, wherein a first dipole moment associated with the first molecule and a second dipole moment associated with the second molecule differ from each other by no more than 0.1 D, preferably no more than 0.08, more preferably no more than 0.07 D, and most preferably no more than 0.06 D.

15. The second molecule is water, H 2 O, and / or heavy water, D 2 The method of any of claims 13 and 14, comprising O.

16. The method according to any of the preceding claims, wherein the first material is selectively removed such that essentially no second material (O, P, D, ML, S) of the object is removed.

17. 17. The method according to claim 16, wherein the method further comprises removing at least one intermediate material (P) disposed between the first material and the second material (D, ML, S).

18. The method according to any of the preceding claims, wherein the method further comprises removing at least one surface material (O) of the object.

19. The method of any preceding claim, wherein the particle beam is at least partially based on an accelerating voltage of less than 3 kV, preferably less than 1 kV, more preferably less than 0.6 kV.

20. The method of any of claims 1 to 19, wherein the method further comprises determining an end point of removal based at least in part on detecting electrons emitted from the object.

21. The method of any one of claims 1 to 20, wherein the particle beam comprises an electron beam.

22. The method according to any of the preceding claims, wherein the method is carried out such that opacity defects of the object are repaired.

23. The method according to any of the preceding claims, wherein the object comprises an EUV mask and / or a DUV mask.

24. 1. An apparatus for processing an object for lithography, comprising: a means for providing a first gas; Means for providing a particle beam to a processing area of ​​said object. An apparatus configured to perform the method according to any of the claims 1 to 23.

25. A lithographic object treated by the method of any of claims 1 to 23.

26. A method of processing a semiconductor-based wafer, comprising lithographic transfer of a pattern associated with a lithographic object onto said wafer, said object having been processed according to any of claims 1 to 23.

27. A computer program comprising instructions which, when executed by a computer system, cause said computer system to perform a method according to any of claims 1 to 23 and / or claim 26.

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