Apparatus and method for analyzing and / or processing a sample with a particle beam

Abstract

What is proposed is an apparatus (100) for analyzing and / or processing a sample (200) with a particle beam (112), comprising a sample stage (120) for holding the sample (200), a supply unit (110) for supplying the particle beam (112), an opening (114) for directing the particle beam (112) to a processing position (202) on the sample (200), and a shield (116) for shielding an electric field (E) generated by an electric charge (Q) accumulated on the sample (200). and a supply unit (110) comprising a shield element (116), the shield element (116) covering the opening (114), embodied in a sheet-like form, and comprising a conductive material, the shield element (116) having a convex section (117) that is convex with respect to the sample stage (120), the convex section (117) having a through opening (118) through which the particle beam (112) passes to the sample (200).

Description

Technical Field

[0001] The present invention relates to an apparatus for analyzing and / or processing a sample with a particle beam, as well as to a corresponding method.

[0002] The entire content of the German patent application No. 102020124306.5, which is a priority application, is incorporated herein by reference.

Background Art

[0003] For manufacturing microstructural components, such as integrated circuits, etc., microlithography is used. The microlithography process is carried out using a lithography apparatus having an irradiation system and a projection system. In this case, the image of the mask (reticle) irradiated by the irradiation system is projected onto a substrate, for example, a silicon wafer, which is coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system for the purpose of transferring the mask structure to the photosensitive coating of the substrate by the projection system.

[0004] In this case, the mask, or rather the lithography mask, is used for a large number of exposures, and therefore it is very important that the above-mentioned mask has no defects. Therefore, a great deal of labor is accordingly expended to inspect whether there are any defects in the lithography mask and to repair the identified defects. The size of the defects in the lithography mask can be on the order of the nanometer range. In order to repair such defects, an apparatus that provides a very high spatial resolution for the repair process is required.

[0005] A suitable apparatus for this purpose is one that activates a local etching or deposition process based on a particle beam-induced process.

[0006] European Patent No. 1587128 discloses one such device that uses a beam of altered particles, particularly the electron beam of an electron microscope, to initiate a chemical reaction process. If the sample is non-conductive or has a very low dielectric constant, the use of charged particles can cause the sample to become charged. This can lead to uncontrolled beam deflection, which limits the achievable process resolution. Therefore, it has been proposed to place a shielding element very close to the processing position so that the charging of the sample is minimized and the process resolution and process control are improved.

[0007] For the desired repair process, the process gas has to be moved to the processing position. General process gases can already be very reactive in their ground state, and in addition, during the processing, highly reactive atoms or molecules can occur that, for example, damage the components of the particle beam device and / or deposit on its surface. As a result, the service interval of each particle beam device can be shortened and / or the process can become unstable.

[0008] The processing speed achievable in such a particle beam-induced process depends significantly, among other things, on the process gas pressure at the processing position. To increase the processing speed, it is desirable to have a high process gas pressure at the processing position. This can be achieved, for example, by feeding the process gas through the exit aperture of the particle beam, in which case the process gas can then flow through the particle beam device without being obstructed. On the other hand, from the perspective of the lifetime of the components used, the gas flow of the process gas entering the particle beam device from the processing position should be minimized.

[0009] German Patent Application Publication No. 10208043 discloses a material processing system that can be used, for example, in material processing by material deposition from a gas such as CVD (chemical vapor deposition), or in a method for material removal by a reaction gas during feeding. In particular, in this case, the gas reaction that brings about material deposition or material removal is initiated by an energy beam directed at an area of the workpiece to be processed. SUMMARY OF THE INVENTION

[0010] In light of this background, it is an object of the present invention to provide an improved apparatus for analyzing and / or processing a sample with a particle beam.

[0011] According to a first aspect, an apparatus for analyzing and / or processing a sample with a particle beam is proposed. The apparatus comprises a sample stage for holding the sample and a supply unit for supplying the particle beam. The supply unit comprises an aperture for guiding the particle beam to a processing position on the sample and a shield element for shielding the electric field generated by the charge accumulated on the sample. The shield element covers the aperture, is embodied in a sheet-like manner, and contains a conductive material. Furthermore, the shield element comprises a convex section, which is convex with respect to the sample stage and has a through-opening for the particle beam to pass through to the sample.

[0012] This apparatus has the advantage that the electric field formed between the shield element and the sample due to the charging of the sample or the surface of the sample is less likely to affect the particle beam without control. The convex section of the shield element allows the distance between the shield element and the surface of the sample in the region of the processing position to be maintained very small without having to maintain the entire shield element at a very small distance. For this reason, the complexity in positioning the sample relative to the shield element is reduced. It can also be said that the margin between the sample and the supply unit regarding inclination increases.

[0013] The device comprises a sample stage for holding a sample. Preferably, the sample stage is arranged within a vacuum housing. The sample stage preferably has a positioning unit for positioning the sample stage relative to the supply unit. The positioning unit can be configured, for example, to displace the sample stage along three spatial axes. Further, the positioning unit can be configured to rotate the sample stage about at least one of the above axes, preferably about at least two of the above axes. The sample stage is preferably held by a holding structure in a manner isolated from vibrations and / or actively vibration-damped.

[0014] The particle beam includes charged particles such as, for example, ions, electrons, or positrons. Correspondingly, the supply unit has, for example, a beam generation unit comprising an ion source or an electron source. By means of an electric field and a magnetic field, it is possible to influence a particle beam consisting of charged particles, that is to say, for example, to accelerate, direct, shape, and / or focus it. For this purpose, the supply unit can have several elements configured to generate the corresponding electric field and / or magnetic field. The above elements are arranged, in particular, between the beam generation unit and the shield element. The particle beam is preferably focused onto the processing position. This is understood to mean, for example, that the particle beam has a predetermined diameter, in particular a minimum diameter, when it impinges on the processing position. The supply unit preferably comprises a dedicated housing in which the above-described elements are arranged, and this housing is preferably embodied as a vacuum housing that is maintained at a residual gas pressure of, for example, 10 -7 ~10 -8 mbar.

[0015] The shield element is arranged on the opening of the supply unit through which the particle beam is guided to the processing position on the sample, and as a result, the shield element forms the component of the supply unit that is closest to the sample stage in the beam direction.

[0016] The device is, for example, a scanning electron microscope. In order to achieve high resolution, the electron beam should be controlled very precisely, particularly with regard to the electron energy, the beam diameter (hereinafter referred to as the focus) when it impinges on the sample, and the temporal stability at the moment of impact. In particular, in the case of a sample having sections made of non-conductive or only slightly conductive material, as a result of the incidence of charged particles, an accumulation of charges on the sample that forms an electric field occurs. The particles of the particle beam, and also, for example, the secondary electrons and backscattered electrons detected in order to generate an image, are also affected by the electric field, and as a result, for example, a reduction in resolution can occur.

[0017] The shielding element performs the task of shielding the electric field of the above charges, that is to say, spatially limiting the above electric field, particularly to the smallest possible gap between the shielding element and the sample. For this purpose, the shielding element includes a conductive material. As an example, the shielding element is grounded so that the charges impinging on the shielding element are dissipated.

[0018] The shielding element itself is embodied in the form of a sheet, which forms a three-dimensional shape having a convex section on its surface, and this section is convex with respect to the sample stage. The convex section preferably forms the section closest to the sample stage, that is to say, the distance between the sample stage or the sample and the shielding element is smallest in the region of the convex section.

[0019] On the surface of the shielding element, particularly within the convex section, a convex area is formed.

[0020] In this case, "convex" is understood to mean that the cutting edge of the cross-section passing through the shielding element extending through the convex section has a convex path within the convex section in accordance with the mathematical definition of this term. The above definition is as follows: Function f:C→R, where C is a convex subset of R n is, for all x, y belonging to C and for all a belonging to the interval [0, 1], the following formula (1): f(a·x+(1-a)·y)≦a·f(x)+(1-a)·f(y) Formula (1) When it holds, it is said to be convex.

[0021] In Equation (1), R n represents an n-dimensional vector space over the real numbers. In the case of a shield element, n = 2, that is, R n = R 2 and C is the projection of the shield element onto the sample stage, and f describes the height above the sample stage of the shield element.

[0022] When the relationship between the left side and the right side in Equation (1) does not include the case of "equal to ~", that is, a true "less than ~" is required, and the cases where x = y and a = 0 or a = 1 are excluded, in technical terms, this is also strictly called convex. The convex section of the shield element is preferably embodied such that the cutting edge of the shield element extending through the convex section has a path that is strictly convex in this sense. An example of an area having this shape is a spherical surface or a section of a spherical surface. Furthermore, for a strictly convex function, when a solid of revolution is formed based on this function, a corresponding area is generated, for example, a paraboloid of revolution by rotating a parabola.

[0023] The shield element has a through-opening in the convex section, through which the particle beam passes and is incident on the sample. In the spatial region above the shield element, which is the origin of the particle beam, the electric field of the charges arranged on the sample is effectively shielded by the shield element. It should be noted that the shield element can have further through-openings, in which case one or more through-openings can be arranged outside the convex section of the shield element.

[0024] As an example, the convex section of the shield element is at a distance of up to 1 mm, preferably up to 500 μm, preferably up to 100 μm, preferably up to 50 μm, preferably up to 25 μm, more preferably up to 10 μm from the sample during the analysis or treatment of the sample by the particle beam. The smaller the distance, the smaller the influence that the electrical interference field can have on the particle beam.

[0025] As a result, the particle beam can be controlled very precisely, and the particle beam is not significantly affected by random and / or uncontrollable interference. As a result, very high resolution is possible both during image acquisition, such as in the case of a scanning electron microscope, and during processing methods implemented using the particle beam, such as particle beam induced etching or deposition processes, ion implantation, and / or further structure modification processes.

[0026] The supply unit is an electron column capable of supplying an electron beam having an energy in the range of, for example, 10 eV to 10 keV and a current in the range of 1 μA to 1 pA. However, this may also be an ion source for supplying an ion beam. The particle beam to be focused is preferably focused on the surface of the sample, and an irradiation region having a diameter in the range of, for example, 1 nm to 100 nm is achieved.

[0027] The shielding element has a length and width in the range of, for example, 1 mm to 50 mm.

[0028] The material thickness of the shielding element is, for example, in the range of 1 nm to 100 μm, preferably 10 nm to 100 μm, preferably 100 nm to 50 μm, more preferably 1 μm to 30 μm, and even more preferably 5 μm to 15 μm. The material thickness of the shielding element is selected in a suitable manner particularly according to the expected mechanical and / or thermal loads caused by, for example, a pressure difference, an electrostatic force, etc. When it is intended to achieve a particularly thin material thickness, the shielding element can be embodied, for example, in the form of a film or as a self-supporting film.

[0029] The through-opening has a cross-sectional area in the range of, for example, 100 μm 2 ~2500 μm 2 , preferably 400 μm 2 ~1600 μm 2 , more preferably 750 μm 2 ~1400 μm 2 and has a cross-sectional area within the range of.

[0030] The through-opening has a diameter in the range of, for example, 10 μm to 50 μm, preferably 20 μm to 40 μm, more preferably 25 μm to 35 μm. The diameter is related to, for example, the distance between two points arranged opposite to each other in the through-opening.

[0031] The convex section has a diameter in the range of, for example, 100 μm to 5 mm, preferably 500 μm to 3 mm, preferably 1 mm to 2 mm, and extends, for example, over a distance of at least 10 μm, preferably at least 50 μm, preferably at least 100 μm in the direction towards the sample stage. That is, the difference between the distance between the point closest to the shield element and the sample stage and the distance between the point farthest from the shield element and the sample stage is at least 10 μm, preferably at least 50 μm, preferably at least 100 μm.

[0032] According to one embodiment of the device, the device comprises a gas supply unit configured to supply a process gas through the through-opening of the shield element to a processing position on the sample.

[0033] In this embodiment, the process gas flows through the through-opening in the direction of the particle beam. In this embodiment, it is advantageous if the flow resistance to the through-opening is made as low as possible so that the process gas can be efficiently guided in a targeted manner to the processing position. Furthermore, an aperture may be provided that limits the gas flow towards the supply unit so as to face the particle beam. In this case, the process gas is fed, for example, into the region between the shield element and the aperture. If the shield element has a plurality of openings, the process gas can flow through each of the plurality of openings, which can be advantageous for reducing the flow resistance.

[0034] According to a further embodiment of the device, the device comprises a gas supply unit configured to supply a process gas into the gap, which gap is formed by the sample arranged on the sample stage and by the shield element.

[0035] The process gas flows through this gap to the processing position on the sample. This embodiment is advantageous because the supply of the process gas to the processing position can be well controlled in this way. In particular, the process gas flow entering the supply unit opposite to the beam direction decreases because only the through-opening can be utilized. As a result, corrosion of the supply unit, particularly the detector elements, due to contact with the process gas and / or reactive molecules formed from the process gas can be reduced.

[0036] The supply unit has, for example, a circulation plate with an opening for a particle beam. The gas supply is carried out, for example, via the circulation plate by a supply opening on the side of the circulation plate facing the sample. Thereafter, the process gas can enter the gap between the sample and the shield element and flow to the processing position.

[0037] The sample is, for example, a lithography mask having a feature size in the range of 10 nm to 10 μm. This can be, for example, a transmissive lithography mask for DUV lithography (DUV: "deep ultraviolet", operating light wavelength range 30 - 250 nm), or a reflective lithography mask for EUV lithography (EUV: "extreme ultraviolet", operating light wavelength range 1 - 30 nm), etc. The processing processes carried out in this case include, for example, an etching process in which material is locally removed from the surface of the sample, a deposition process in which material is locally applied to the surface of the sample, and / or similar local activation processes such as the formation of a passivation layer or compression of a layer.

[0038] Suitable process gases for the deposition of materials or the growth of high structures are in particular alkyl compounds of main group elements, metals, or transition elements. Examples of these are cyclopentadienyltrimethylplatinum CpPtMe 3 (Me = CH 4 ), methylcyclopentadienyltrimethylplatinum MeCpPtMe 3 , tetramethyltin SnMe 4 , trimethylgallium GaMe 3 , ferrocene Cp 2 Fe, bis-allylchromium Ar2 Cr and / or carbonyl compounds of main group elements, metals, or transition elements, such as chromium hexacarbonyl Cr(CO) 6 , molybdenum hexacarbonyl Mo(CO) 6 , tungsten hexacarbonyl W(CO) 6 , dicobalt octacarbonyl Co 2 (CO) 8 , triruthenium dodecacarbonyl Ru 3 (CO) 12 , iron pentacarbonyl Fe(CO) 5 etc., and / or alkoxide compounds of main group elements, metals, or transition elements, such as tetraethyl orthosilicate Si(OC 2 H 5 ) 4 , tetraisopropoxytitanium Ti(OC 3 H 7 ) 4 etc., and / or halide compounds of main group elements, metals, or transition elements, such as tungsten hexafluoride WF 6 , tungsten hexachloride WCl 6 , titanium tetrachloride TiCl 4 , boron trifluoride BF 3 , silicon tetrachloride SiCl 4 etc., and / or complexes containing main group elements, metals, or transition elements, such as copper bis-(hexafluoroacetylacetonate) Cu(C 5 F 6 HO 2 ) 2 , dimethylgold trifluoroacetylacetonate Me 2 Au(C 5 F 3 H 4 O 2 ) etc., and / or organic compounds, such as carbon monoxide CO, carbon dioxide CO 2 , aliphatic and / or aromatic hydrocarbons, etc.

[0039] Suitable process gases suitable for etching the material are, for example, xenon difluoride XeF 2 , xenon dichloride XeCl2 、Xenon tetrachloride XeCl 4 、Water vapor H 2 O, Heavy water D 2 O, Oxygen O 2 、Ozone O 3 、Ammonia NH 3 、Nitrosyl chloride NOCl, and / or the following halide compounds: XNO, XONO 2 、X 2 O, XO 2 、X 2 O 2 、X 2 O 4 、X 2 O 6 、where X is a halide, and is one of them. A further process gas for etching the material is specified in the applicant's US Patent Application No. 13 / 0103281.

[0040] For example, as an additive gas that can be mixed with the process gas in a certain ratio to better control the processing process, for example, hydrogen peroxide H 2 O 2 、Nitrous oxide N 2 O, Nitrogen oxides NO, Nitrogen dioxide NO 2 、Nitric acid HNO 3 、And other oxidizing gases such as oxygen-containing gases, and / or, Chlorine Cl 2 、Hydrogen chloride HCl, Hydrogen fluoride HF, Iodine I 2 、Hydrogen iodide HI, Bromine Br 2 、Hydrogen bromide HBr, Phosphorus trichloride PCl 3 、Phosphorus pentachloride PCl 5 、Phosphorus trifluoride PF 3 、And other halide compounds such as halogen-containing gases, and / or, Hydrogen H 2 、Ammonia NH 3 、Methane CH 4 、And other reducing gases such as hydrogen-containing gases. The above additive gases can be used, for example, as a buffer gas in the etching process, as a passivation medium, etc.

[0041] According to a further embodiment of the device, the gas supply part comprises a supply channel incorporated in the shielding element.

[0042] This embodiment enables the process gas to be guided very precisely to the processing position. This improves the speed and efficiency of the particle beam induced processing process because there are always sufficient amounts of process gas molecules present to avoid depletion. In this embodiment, the shielding element is in particular manufactured by a special manufacturing method, in particular the LIGA manufacturing method (LIGA: abbreviation from the German Lithographie, Galvanik und Abformung [lithography, electroplating, and molding]).

[0043] The shielding element can be embodied, for example, as being partially hollow, in which case the interior of the shielding element forms the supply channel. At the outer edge of the shielding element, the interior is fluidically connected to the gas supply part. In this case, transfer pieces or attenuation pieces can be used. It is advantageous for the outlet opening for supplying the gas to be arranged as close as possible to the through-opening in the convex region.

[0044] In a further example, the shielding element comprises a microporous material covered with an airtight coating having an inlet for supplying the process gas and an outlet through which the process gas flows out. The outlet is preferably formed in the convex section opposite the processing position.

[0045] In a plurality of embodiments of the device, the device is configured to establish electrical contact with the sample by means of the convex section of the shielding element. This can be particularly advantageous in the case of samples having a conductive surface because the charge can flow directly away from the surface of the sample, and as a result, no interfering electric field is formed.

[0046] In a further embodiment, a protective layer can be deposited around a processing position on the surface of the sample by a particle beam induced process before the sample contacts the shielding element. The protective layer has advantageous conductivity and also serves as a protection against mechanical damage to the sample caused by the shielding unit when the shielding unit is in contact with the sample. The protective layer can be removed again after completion of the analysis or processing, for example by a particle beam induced etching process.

[0047] According to a further embodiment of the device, the through-opening includes the point of the minimum distance between the shielding element and the sample stage.

[0048] This is understood to mean that the geometrically minimum distance between the shielding element and the sample stage in the case where the shielding element does not have an opening exists at the point of the shielding element occupied by the through-opening. In this case, in particular the edge of the through-opening forms the point of the shielding element closest to the sample stage.

[0049] According to a further embodiment of the device, the shielding element comprises a planar section from which a convex section extends in the direction of the sample stage.

[0050] The planar section can for example serve to fix the shielding element to a supply device, for example a holding structure at the edge of the opening. The planar section preferably extends substantially parallel to the surface of the sample during the analysis or processing of the sample.

[0051] The planar section of the shielding element can be made of a material different from that of the convex section of the shielding element. In this case, the shielding element can be composed of two parts, a planar section and a concave section, in which case these two parts can be screwed together, adhesively bonded to each other, welded to each other, and / or connected to each other by corresponding suitable engagement elements.

[0052] According to a further embodiment of the device, the convex section is embodied in a funnel-shaped manner, in particular having a circular cross-section.

[0053] It can also be said that the convex section forms the surface of a solid of revolution based on a convex function.

[0054] However, the convex section can also have a cross-section deviating from a circular shape, in particular an elliptical cross-section.

[0055] Preferably, the convex section is embodied so as to taper towards the through-opening.

[0056] According to a further embodiment, the convex section is embodied in such a way that a connecting line connecting two points on the surface of the convex section of the shield element lies outside the shield element for any combination of two points on the surface of the convex section of the shield element.

[0057] It can also be said that the convex section forms an area that satisfies being strictly convex from a mathematical point of view. A function is strictly convex when in formula (1) the left side is required to be truly "less than" the right side.

[0058] Examples of areas having this shape are a spherical surface or a section of a spherical surface. Furthermore, a strict convex function such as a parabola generates a corresponding area, for example a paraboloid of revolution by rotating the parabola, when a solid of revolution is formed based on this function.

[0059] The fact that the connecting line lies outside is understood to mean that the connecting line has no common point with the convex section. From this, it follows that this connecting line also does not intersect the convex section or the shield element. It should be noted that a planar area does not satisfy this embodiment because the connecting line between two points of the plane itself lies within that plane.

[0060] According to a further embodiment of the device, the shielding element comprises a layer made of a conductive material on its surface, and the layer thickness of this layer is greater than or equal to the penetration depth of the particles of the particle beam into the material.

[0061] This has the advantage that no charge can accumulate in or on the shielding element itself. For example, a material that can form a natural oxide layer that is insufficient as a conductor may not be very suitable.

[0062] In an advantageous embodiment, the shielding element consists entirely of a conductive material. This can be a pure material, or else an alloy, a composite material, and / or a material having a microstructure.

[0063] The requirements for the material vary depending on the particular application. In addition to conductivity, the magnetic properties and the chemical properties of the material can be considered relevant. Preferably, the material is, for example, non-magnetic. Furthermore, the material is preferably chemically inert, so that this material reacts only very slightly or not at all with other reaction products and / or process gases fed together with them. This enables the shielding element to have a long service life.

[0064] The shielding element contains, for example, noble metals. By way of example, the shielding element contains at least one element from a list including gold, nickel, palladium, platinum, iridium. In a plurality of embodiments, the shielding element is formed of gold or nickel.

[0065] The shielding element preferably has a very smooth surface. By way of example, the RMS value of the surface roughness is at most 50 nm, preferably at most 10 nm, preferably at most 5 nm, more preferably at most 2 nm.

[0066] According to a further embodiment of the device, the shielding element has exactly one through-opening.

[0067] The shielding element can also be embodied as a single-hole aperture. The through-opening is preferably embodied as circular. Similarly, it is possible to have additional opening geometries such as square, hexagonal, octagonal, rectangular, and / or elliptical.

[0068] The through-opening that defines the side wall of the shielding element preferably has an inclination with respect to the symmetry axis of the through-opening, whereby the side wall forms a cone that opens upward facing the beam direction. As a result, the opening cross-section of the through-opening on the sample side is smaller than that on the opposite side. This has the advantage that secondary electrons or backscattered electrons from the sample can be detected at a larger solid angle. This can improve the detection efficiency, signal-to-noise ratio, and / or resolution.

[0069] According to a further embodiment of the device, the shielding element has a plurality of through-openings separated from each other by webs.

[0070] The web is formed, for example, by the material of the shielding element that exists between two through-openings and separates them from each other. The web preferably has the smallest possible width. Depending on the geometry of the through-opening, the web can have a constant width or else various widths. By way of example, the web has a width in the range from 1 μm to 100 μm, preferably from 1 μm to 50 μm, preferably from 5 μm to 30 μm, more preferably from 10 μm to 20 μm.

[0071] It can also be said that the shielding element forms a mesh or is formed of a mesh.

[0072] A shielding element having a plurality of through-openings is advantageous in that it allows the particle beam to reach a larger section of the sample or the surface of the sample without impairing the shielding of the electric field. It can also be said that the processing position or processing area can be enlarged. As a result, an improvement in the overview can be achieved. However, in the case of a plurality of through-openings, when gas is fed into the gap between the sample and the shielding element, an increase in the gas flow facing the beam direction may become apparent.

[0073] When the shielding element has a plurality of through openings, it is preferred that these through openings be arranged in the vicinity around the deepest point of the convex section of the shielding element. As an example, the deepest through opening includes the deepest point of the convex section, and additional through openings are arranged in a manner directly adjacent to this deepest through opening.

[0074] As an example, the convex section can be embodied such that there is a deepest planar region instead of a deepest point, and a plurality of through openings are arranged within the above-mentioned region.

[0075] According to a further embodiment of the device, the through openings each have a hexagonal cross-section.

[0076] The geometry of the through openings affects the electric field profile of the electric field to be shielded below the through openings and may also affect the particle beam.

[0077] The hexagonal geometry enables a high area occupancy rate and achieves a good balance with further electrostatic properties.

[0078] Further possible geometries include a square geometry, a rectangular geometry, a circular geometry, an elliptical geometry, a pentagonal geometry, an octagonal geometry, and the like.

[0079] The arrangement of the plurality of through openings relative to each other can be regular or, alternatively, irregular. Furthermore, the through openings can be arranged in a manner rotated relative to each other about a symmetry axis.

[0080] According to a further embodiment of the device, the web has a shape such that the sample stage side cross-sectional area of each one of the plurality of through openings in a first plane perpendicular to the surface normal of the shielding element above the through openings is smaller than the opening side cross-sectional area of the corresponding through opening in a second plane parallel to the first plane.

[0081] According to a further embodiment of the device, one of the plurality of through openings has a geometric feature that distinguishes the through opening from further through openings.

[0082] This embodiment is advantageous when the plurality of through openings all have, for example, the same geometric shape and are regularly arranged, because in that case it can be difficult to distinguish the through openings from each other. In this case, therefore, it is possible, for example, to identify the through opening that includes the point of the shielding element that is at the minimum distance from the sample stage or the sample. It can also be said that the through opening having the geometric feature marks a reference position, based on which the positions of further through openings can be determined unambiguously.

[0083] As an example, the distinguishable through opening has a marking. Such a marking can be formed by a section having additional material and / or by a section having missing material.

[0084] It is also possible for the plurality of through openings to have markings or the like that are distinguishable from each other, in which case there will be a plurality of marked through openings that can be determined unambiguously.

[0085] The through opening having this geometric feature can have a geometric shape different from that of further through openings. As an example, two through openings can be connected to form a single through opening, in which case that through opening forms a double through opening.

[0086] Proceeding from the distinguishable through opening, it is possible to determine the deepest through opening, which is particularly optimal for the analysis and / or processing process because the shielding of the electric field is best at this through opening.

[0087] According to a further embodiment of the device, one of the plurality of through openings includes the point where the distance between the shielding element and the sample stage is minimum, and further through openings are arranged symmetrically with respect to this one through opening.

[0088] The arrangement of the through-opening can in particular be rotationally symmetric and / or mirror-symmetric. The symmetric arrangement can have at least one axis of symmetry.

[0089] According to a further embodiment of the device, the device comprises a beam generation unit and a beam guiding element. The beam guiding element is arranged between the beam generation unit and the shielding element and is configured to guide a particle beam. Furthermore, a voltage source for applying a voltage between the shielding element and the beam guiding element is provided.

[0090] The beam generation unit is configured to generate a particle beam. This is, for example, a hot cathode for generating an electron beam. The beam guiding unit is, for example, configured to accelerate the particles in the particle beam. The beam guiding unit can be configured to deflect the particle beam, for example, to focus the particle beam, to shape the particle beam, and the like.

[0091] As a result of applying a voltage between the shielding element and the beam guiding element, an electric field is generated between these elements. The particle beam passes through this electric field and can thus be affected accordingly, for example, accelerated, decelerated, shaped, and / or deflected by the electric field. As a result, a direct influence can be exerted on the particle beam up to the surface of the sample.

[0092] The flight path of the charged particles flying through the through-opening opposite to the direction of the particle beam emitted from the sample is also affected by the electric field. As an example, by appropriately setting the potentials of the shielding element and the beam guiding element, it is possible to establish an energy filter for secondary electrons and backscattered electrons. In this case, the sample or the sample stage is suitable as a reference point, in which case the energy filter, for example, the shielding element, has a negative potential and the beam guiding element has a positive potential with respect to the sample or the sample stage.

[0093] Furthermore, since the shielding element has a specific electric potential, an electric field is also generated between the shielding element and the sample. This electric field can be set so that secondary electrons are more favorably extracted from the deep structure on the surface of the sample. For this purpose, it is advantageous if the shielding element has a positive electric potential with respect to the sample or the sample stage. As a result, this has the advantage that the detection of electrons emitted from deeper regions on a sample having a high aspect ratio can be improved. The aspect ratio is understood to mean, for example, the ratio of the height to the width of the structure. For example, if the height / width is ≧ 0.5, it indicates a high aspect ratio. This also has the further advantage that, for example, secondary electrons emitted by the shielding element can be captured. As a result, unwanted chemical reactions that could be initiated by such secondary electrons can be avoided.

[0094] In a plurality of embodiments of the device, the shielding element is fixed to the supply unit by a holding device.

[0095] The connection between the holding device and the shielding element can be implemented, for example, by welding, clamping, and / or adhesive bonding.

[0096] In a plurality of embodiments, the holding device and the shielding element are embodied as one component, in particular integrally. This is made possible by a special manufacturing method, in particular the LIGA manufacturing method (LIGA: an abbreviation from the German words Lithographie, Galvanik und Abformung [lithography, electroplating, and molding]).

[0097] According to a further embodiment of the device, the shielding unit is fixed to the supply unit by a holding device, in which case the holding device and the shielding element are electrically insulated from each other. A further voltage source is provided for applying a voltage between the holding device and the beam guiding element and / or the shielding element.

[0098] In this embodiment, two electric fields are formed. There is a first electric field between the beam guiding element and the holding device, and a second electric field between the holding device and the shielding element. As a result, in particular, two electric field sections are generated below the beam guiding element, and these electric field sections can be used to focus a particle beam, for example. In that case, it is possible not to use magnetic focusing, which can cause a residual polarization effect or the like.

[0099] When the particle beam is an electron beam, the holding device is preferably set to a negative potential with respect to the beam guiding element, whereby the electrons are decelerated. For example, the energy of an electron beam that has been given an energy higher than the desired incident energy on the sample, also called the boost voltage or Uboost, can be set to the desired energy.

[0100] According to a further embodiment of the device, the shielding element is held in an electrically insulated manner, and a detection unit is provided for detecting a current flowing away from the shielding element.

[0101] The detection unit, for example a current measuring device, can be used as a detector in various ways. In particular, in cooperation with a voltage applied between the shielding element and the holding device or the beam guiding element and acting as an energy filter, it is possible to distinguish, for example, secondary electrons having a low energy in the range of a few electron volts to a few tens of electron volts from backscattered electrons having a higher energy within the range of the beam energy. The shielding element can in that case be used, for example, as a secondary electron detector.

[0102] Since the backscattering efficiency of the backscattered electrons depends on the electron energy and the atomic number of the material, information about the atomic number of the material can also be obtained by means of the energy filter.

[0103] Furthermore, the gas pressure within the region of the shield element can be estimated from the detected current because there is a positive correlation between the gas pressure and the current. As the gas pressure increases, more collisions occur between the particles of the particle beam and the gas molecules, and thus stronger scattering occurs. As a result, the number of particles scattered towards the shield element increases, and thus the detected current also increases.

[0104] According to a further embodiment of the device, the shield element comprises a plurality of sections that are electrically insulated from each other and define a through-opening, in which case a voltage can be applied between any two sections arranged opposite each other by a corresponding voltage source.

[0105] In this way, the shield element can additionally be used as a deflection unit. Thus, a separate deflection unit arranged above the shield element can be omitted. Thus, this simplifies the structure of the device and furthermore, the efficiency can be improved. First, the solid angle at which backscattered electrons or secondary electrons can be detected is not further reduced by a separate deflection unit. Second, since the through-opening has a diameter of, for example, only 30 μm to 150 μm, the voltage at which the deflection unit operates can be made lower. The smaller the through-opening, the greater the gradient of the electric field for the same voltage.

[0106] Preferably, the shield unit comprises eight such sections. In that case, the shield unit can also be called an octupole unit.

[0107] In this embodiment, the shield element can also furthermore be used as a stigmator and / or a lens for the particle beam, in particular for focusing the particle beam onto the sample. The stigmator is configured to correct for astigmatism.

[0108] Furthermore, the shielding element can serve as a "beam blanker". In a conventional particle beam column, a beam blanker (used to quickly switch the particle beam on and off) is arranged at a position in the column where the particles have a high energy. For this reason, it is also necessary to use a high voltage to deflect the particle beam. In contrast, in the present embodiment, the beam is deflected at a position where its energy has already decreased, and for this reason, such a high voltage is not necessary. Therefore, the structure can be simplified, and furthermore, a faster switching time becomes possible. By using a current measurement device, it is further possible to determine the current of the particle beam when the particle beam is directed towards the shielding element.

[0109] In a plurality of embodiments, a capacitance measurement device configured to check the capacitance between the shielding element and the sample can be provided.

[0110] As an example, the distance between the shielding element and the sample can be checked based on the capacitance. This is particularly possible in the case of a sample that is conductive or has a conductive section.

[0111] According to a further embodiment of the apparatus, a plurality of shielding elements are provided that are arranged one after another along the beam direction and each cover an opening. At least one of the plurality of shielding elements is held in a displaceable manner for the purpose of providing an aperture with an adjustable aperture value.

[0112] The relative position of the shielding element held in a displaceable manner with respect to a further shielding element of the shielding element held in a displaceable manner can be made adjustable by the shielding element held in a displaceable manner. As a result, an aperture with an adjustable beam direction is obtained. By reducing the size of the aperture, it is possible to reduce, for example, the process gas volume flow rate facing the beam direction.

[0113] The shielding element is preferably arranged with respect to the opening such that the influence on the beam position due to fluctuations of the focus within a pre-determined focus interval and / or fluctuations of the beam energy within a pre-determined energy interval is minimized, and / or the influence on the detection efficiency is minimized.

[0114] The process of varying the focus and / or the beam energy may also be referred to as "wobbling".

[0115] This arrangement of the shielding element is set once, in particular for each supply unit, when the shielding element is attached to the supply unit. By optimizing the position as described above, it is ensured that the device has high robustness, particularly with regard to resolution.

[0116] According to a second aspect, a method for analyzing and / or processing a sample with a particle beam by means of the device according to the first aspect is proposed. In a first step, the sample is placed on a sample stage. In a second step, a particle beam is supplied. In a third step, the particle beam is radiated through a through-opening onto a processing position on the sample.

[0117] This method has the same advantages as those already described for the device.

[0118] The embodiments and features described with respect to the device also apply mutatis mutandis to the proposed method, and vice versa.

[0119] According to one embodiment of the method, the method additionally includes the step of feeding a process gas to the processing position, in which case the process gas flows to the processing position on the sample only through the gap formed by the shielding unit and the sample.

[0120] According to a further embodiment of the method, the method includes bringing the surface of the sample into contact with the shielding element, in which case the convex section of the shielding element has at least one contact point with the surface of the sample.

[0121] If the sample has a conductive surface, charges can flow away through the electrical contacts and the shielding unit, thus avoiding charging of the entire sample in this way.

[0122] In the case of a delicate sample, a protective layer that is locally deposited on the surface of the sample in advance can be provided. The protective layer is formed, for example, in the area around the processing position where the shielding element first contacts the sample. The protective layer can be generated particularly by a particle beam induced process. The protective layer has advantageous conductivity. The protective layer is preferably manufactured from a material that can be removed again without leaving residues and without damaging the surface of the sample by a selective etching process. The protective layer can be removed again in a subsequent purge process or in a particle beam induced etching process.

[0123] "One (A(n)), one (one)" in this case should not necessarily be understood as being limited to exactly one element. Rather, a plurality of elements, such as two, three, or more, can be provided. Any other numbers used in this specification should not be understood in the sense that there is a limitation to exactly that number of elements stated. Rather, a deviation in number is possible up and down, unless otherwise indicated.

[0124] Further possible implementations of the present invention also include combinations of features or embodiments that are not explicitly stated, described above or below with respect to the exemplary embodiments. In this case, those skilled in the art will also add the individual aspects as improvements or supplements to each basic form of the present invention.

[0125] Further advantageous configurations and aspects of the present invention are the subject matter of the dependent claims and also of the exemplary embodiments of the present invention described below. In the following text, the present invention will be described in more detail with reference to the accompanying drawings, based on the preferred embodiments.

Brief Description of the Drawings

[0126]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14A - 14D

Figure 15

Embodiments for Carrying out the Invention

[0127] The same elements or elements having the same function are denoted by the same reference numerals in the figures, unless otherwise indicated. It should also be noted that the depictions in the figures are not necessarily drawn to scale.

[0128] FIG. 1 shows a schematic diagram of a first exemplary embodiment of an apparatus 100 for analyzing and / or processing a sample 200 (see FIGS. 2, 3, or 12) with a particle beam 112. The apparatus 100 is preferably arranged within a vacuum housing (not shown). The apparatus 100 comprises a supply unit 110 for supplying the particle beam 112 and a sample stage 120 for holding the sample 200, and the sample stage is arranged below the supply unit 110.

[0129] The supply unit 110 in particular comprises a particle beam generation unit 111 for generating the particle beam 112. The particle beam 112 consists of charged particles, for example ions or electrons. In the example of FIG. 1, an electron beam is involved. The supply unit 110 is thus also called an electron column, and in that case, the apparatus 100 forms, for example, a scanning electron microscope. The electron beam 112 is guided by a beam guiding element (not shown in FIG. 1). This is also called an electron optical unit. Furthermore, the electron column 110 of FIG. 1 comprises a detector (not shown) for detecting electron signals emitted, for example, from backscattered electrons and / or secondary electrons.

[0130] The electron column 110 is, for example, 10 -7 mbar to 10 -8It has a dedicated vacuum housing that is evacuated to a residual gas pressure of mbar. The opening 114 for the electron beam 112 is arranged on the lower surface. The opening 114 is covered by a shield element 116. The shield element 116 is embodied in a sheet-like manner and includes a conductive material. By way of example, the shield element 116 is formed of gold. The shield element 116 has a convex section 117, which is convex with respect to the sample stage 120. The convex section 117 is curved in the direction of the sample stage 120. The convex section 117 has a through-opening 118 for the particle beam 112 to pass through. The through-opening 118 particularly includes the point of the convex section 117 closest to the sample stage. The distance between the shield element 116 and the sample stage 120 is thus smallest in the region of the through-opening 118. During operation of the device 100, the distance between the through-opening 118 and the sample 200 is preferably 5 μm to 30 μm, preferably 10 μm. Preferably, the sample stage 120 has a positioning unit (not shown), whereby the distance between the sample stage 120 and the electron column 110 can be set.

[0131] The shield element 116 may have a planar region 116A (see FIGS. 14A to 14D), from which the convex section 117 projects. The planar region 116A preferably extends radially from the upper end of the convex section 117. The shield element 116 is fixed to the opening 114 of the electron column 110, for example, at the outer edge of the planar region 116A.

[0132] A ground potential is applied to the shield element 116. The shield element is thus configured to shield the electric field E. To clarify this, in FIG. 1, as an example, a charge Q generating the electric field E is illustrated. The charge Q is illustrated below the shield element 116 within a region where it is considered that the processing region 202 (see FIGS. 2, 3, or 12) of the sample 200 will be deployed during the use of the apparatus 100. In the case of the sample 200 which is (at least partially) non-conductive or has very low conductivity, when the particle beam 112 is incident on the sample 200, as illustrated in FIG. 1, charging of the sample 200 and thus formation of the electric field E occur. In FIG. 1, as an example, a negative charge Q resulting from the incidence of the electron beam 112 is shown.

[0133] As a result of shielding the electric field E, firstly, an improvement in the accuracy with respect to the collision point on the sample 200 and furthermore the focusing position of the electron beam 112 is achieved, thereby improving the resolution and process control. Secondly, the flight trajectories of the backscattered electrons and secondary electrons flying in the direction of the beam supply unit 111 opposite to the electron beam 112 are not affected so much, thereby similarly improving the resolution, and process control, and furthermore the sensitivity.

[0134] FIG. 2 shows an excerpt from a schematic diagram of a second exemplary embodiment of an apparatus 100 for analyzing and / or processing a sample 200 with a particle beam 112. Unless otherwise described differently below, the apparatus 100 of FIG. 2 may have the same features as the apparatus 100 of FIG. 1. The example shown is particularly configured to perform a particle beam induced processing process.

[0135] During operation of the apparatus 100, the sample stage 120 on which the sample 200 is disposed on the surface is positioned below the supply unit 110 such that the through opening 118 is deployed above the processing position 202 on the sample 200 in the beam direction. A gap is formed between the sample 200 and the supply unit 110, particularly the shield element 116.

[0136] In this example, the supply unit 110 has a gas supply unit 130 configured to feed a process gas PG into the gap. The process gas PG flows along the gap and as a result reaches the processing position 202 on the sample 200. The gas supply unit 130 thus ensures that, firstly, sufficient process gas PG is supplied to the processing position 202 and, secondly, the volumetric flow rate of the process gas PG entering the supply unit 110 through the through-opening 118 is relatively small, and is much smaller in particular than when the process gas PG is guided through the through-opening 118 from above to the processing position 202.

[0137] The sample 200 is, for example, a lithography mask having a feature size in the range from 10 nm to 10 μm. This can be, for example, a transmissive lithography mask for DUV lithography (DUV: "deep ultraviolet", operating light wavelength range 30 - 250 nm), or a reflective lithography mask for EUV lithography (EUV: "extreme ultraviolet", operating light wavelength range 1 - 30 nm). The processing processes carried out in this case include, for example, an etching process in which material is locally removed from the surface of the sample 200, a deposition process in which material is locally applied to the surface of the sample 200, and / or similar local activation processes such as the formation of a passivation layer or the compression of a layer.

[0138] The process gas PG can include a mixture of multiple gaseous substances. A suitable process gas PG for the deposition of materials or the growth of high structures is in particular an alkyl compound of a main group element, a metal, or a transition element. Examples of these are cyclopentadienyltrimethylplatinum CpPtMe 3 (Me = CH 4 ), methylcyclopentadienyltrimethylplatinum MeCpPtMe 3 , tetramethyltin SnMe 4 , trimethylgallium GaMe 3 , ferrocene Cp 2 Fe, bis-allylchromium Ar 2 Cr, and / or a carbonyl compound of a main group element, a metal, or a transition element, for example, chromium hexacarbonyl Cr(CO)6 , molybdenum hexacarbonyl Mo(CO) 6 , tungsten hexacarbonyl W(CO) 6 , dicobalt octacarbonyl Co 2 (CO) 8 , triruthenium dodecacarbonyl Ru 3 (CO) 12 , iron pentacarbonyl Fe(CO) 5 and / or alkoxide compounds of main group elements, metals, or transition elements, such as tetraethyl orthosilicate Si(OC 2 H 5 ) 4 , tetraisopropoxytitanium Ti(OC 3 H 7 ) 4 and / or halide compounds of main group elements, metals, or transition elements, such as tungsten hexafluoride WF 6 , tungsten hexachloride WCl 6 , titanium tetrachloride TiCl 4 , boron trifluoride BF 3 , silicon tetrachloride SiCl 4 and / or complexes containing main group elements, metals, or transition elements, such as copper bis-(hexafluoroacetylacetonate) Cu(C 5 F 6 HO 2 ) 2 , dimethylgold trifluoroacetylacetonate Me 2 Au(C 5 F 3 H 4 O 2 ) and / or organic compounds, such as carbon monoxide CO, carbon dioxide CO 2 , aliphatic and / or aromatic hydrocarbons, etc.

[0139] Suitable process gases suitable for etching the material are, for example, xenon difluoride XeF 2 , xenon dichloride XeCl 2 , xenon tetrachloride XeCl 4 , water vapor H 2 O, heavy water D 2O, oxygen O 2 , ozone O 3 , ammonia NH 3 , nitrosyl chloride NOCl, and / or the following halide compounds: XNO, XONO 2 , X 2 O, XO 2 , X 2 O 2 , X 2 O 4 , X 2 O 6 , where X is a halide, and is one of them.

[0140] For example, as an additive gas that can be mixed with the process gas PG at a certain ratio to better control the treatment process, for example, hydrogen peroxide H 2 O 2 , nitrous oxide N 2 O, nitrogen oxides NO, nitrogen dioxide NO 2 , nitric acid HNO 3 , and other oxidizing gases such as oxygen-containing gases, and / or, chlorine Cl 2 , hydrogen chloride HCl, hydrogen fluoride HF, iodine I 2 , hydrogen iodide HI, bromine Br 2 , hydrogen bromide HBr, phosphorus trichloride PCl 3 , phosphorus pentachloride PCl 5 , phosphorus trifluoride PF 3 , and other halides such as halogen-containing gases, and / or, hydrogen H 2 , ammonia NH 3 , methane CH 4 , and other reducing gases such as hydrogen-containing gases. The above additive gas can be used, for example, as a buffer gas, a passivation medium, etc. in an etching process.

[0141] Figure 3 shows an excerpt from a schematic diagram of a third exemplary embodiment of an apparatus 100 for analyzing and / or processing a sample 200 with a particle beam 112. This particularly includes a specific embodiment of the apparatus 100 shown in Figure 2.

[0142] In this case, the shielding element 116 comprises a channel forming the last section of the path of the gas supply unit 130. Accordingly, in this case, the process gas PG is guided through the shielding unit 116. In this way, the process gas PG can be conveyed very close to the processing position 202. As a result, leakage of the process gas PG to the surroundings of the apparatus 100 can be reduced, and consumption of the process gas PG can be suppressed. In particular, at the processing position 202, a higher process gas pressure and less process gas consumption can be achieved simultaneously. As a result, the processing speed can be increased.

[0143] The shielding element 116 having the integrated gas supply unit is manufactured, for example, by a special manufacturing method, in particular the LIGA manufacturing method (LIGA: an abbreviation from the German Lithographie, Galvanik und Abformung [lithography, electroplating, and molding]).

[0144] FIG. 4 schematically shows six different exemplary embodiments (A) to (F) of the shielding element 116. FIG. 4 shows the shielding element 116 in a plan view, for example, as viewed from the beam direction. For this reason, the convex section 117 is shown as a dotted line in each case. By way of example, the convex section 117 starts from this line, and on the outside, the shielding element can be embodied in a particularly planar manner. All of the examples illustrated in FIG. 4 include a shielding element 116 having a circular outer edge, but geometric shapes deviating therefrom are also possible. Each of the illustrated shielding elements 116 can be used in the apparatus 100 according to any one of FIGS. 1 to 3, FIG. 7, FIG. 8, FIG. 10, or FIG. 12.

[0145] In the example of FIG. 4(A), the shielding element 116 is embodied in the form of a single-hole aperture. The shielding element 116 has, for example, a diameter of 4 mm, and the through-opening 118 has a diameter of 30 μm. The convex section 117 has, for example, a diameter of 2 mm.

[0146] In the example of FIG. 4(B), the shield element 116 has a plurality of through openings 118, but only one of them is specified by reference numerals for clarity. A web 119 is provided between two of the through openings 118, and the web is made of, for example, the material of the shield element 116. As an example, the shield element 116 is formed of a gold film having a thickness of 10 μm, and the through openings 118 are formed by a punching method. In this example, a plurality of through openings 118 are provided within the convex section 117 of the shield element 116. In this example, all the through openings 118 have the same size and geometry, but a plurality of through openings 118 having various sizes and / or various geometries may be provided.

[0147] In the example of FIG. 4(C), the shield element 116 has a plurality of through openings 118, but only one of them is specified by reference numerals for clarity. Here, all the through openings 118 have a hexagonal geometry. Therefore, each web 119 between two of the through openings 118 has a constant width. In this example, a plurality of through openings 118 are similarly provided in at least a part of the convex section 117.

[0148] In the example of FIG. 4(D), the shield element 116 has a plurality of through openings 118, but only one of them is specified by reference numerals for clarity. Here, all the through openings 118 have a square geometry. Therefore, each web 119 between two of the through openings 118 has a constant width. In this example, a plurality of through openings 118 are similarly provided in at least a part of the convex section 117.

[0149] In the example of FIG. 4(E), the shield element 116 has a plurality of through openings 118, but only one of them is specified by reference numerals for clarity. Here, all the through openings 118 have a hexagonal geometry. However, through openings 118 of different sizes are provided.

[0150] The largest through-opening 118 is arranged centrally within the convex section 117. The central through-opening 118 includes the point of the shield element 116 closest to the sample stage 120 (see FIGS. 1 - 3, 5, 7, 8, 10, or 12). The central through-opening 118 is preferably the through-opening 118 through which a particle beam 112 (see FIGS. 1 - 3, 7, 8, 10, or 12) for analyzing or processing the sample 200 is guided. In a pattern directly adjacent to the central through-opening 118, six somewhat smaller through-openings 118 are arranged. The web width of the web 119 between these through-openings 118 is, for example, 10 μm. Further radially outwards, a total of twelve further through-openings 118 are arranged, particularly in a hexagonal pattern. The web width between these outer through-openings 118 is, for example, 50 μm.

[0151] In the shield element 116 of this example, firstly, it is possible to generate an overview record of the sample 200 by scanning each of the through-openings 118 with the particle beam 112, and secondly, simultaneously, to reduce the free cross-sectional area by the wide web 119, thereby reducing the volumetric flow rate of the process gas passing through the shield element 116.

[0152] In the example of FIG. 4(F), the shield element 116 has a plurality of through-openings 118, but only one of them is specifically identified by reference numerals for clarity. Here, all the through-openings 118 have a hexagonal geometry. In this example, all the through-openings 118 are of the same size and the web 119 has a constant width, for example 40 μm. The shield element 116 of this example has, for example, the same advantages as the shield element 116 of example (E).

[0153] FIG. 5 schematically shows an excerpt from a cross-section through one exemplary embodiment of a shield element 116 having a plurality of through openings 118, with only one of the through openings 118 being shown in this excerpt of FIG. 5. The shield element 116 can be implemented, for example, as described with reference to FIGS. 1-4. The exit opening 118 is defined by two webs 119. The cross-section of the web 119 is such that the sample stage side cross-sectional area 118A in a first plane perpendicular to the surface normal N of the shield element 116 over the through opening 118 is smaller than the opening side cross-sectional area 118B of the through opening 118 in a second plane parallel to the first plane.

[0154] It can be said that the web 119 tapers upward. The web 119 can be implemented, for example, as having a triangular or trapezoidal shape. What is achieved by this cross-section is that, as illustrated by a cone having an opening angle α depicted in FIG. 5 as an example, backscattered electrons or secondary electrons emitted by the sample 200 can be detected within a larger solid angle range with respect to the shield element 116.

[0155] As a result, the mechanical stability of the shield element 116 remains the same while the detection efficiency and / or resolution can be improved.

[0156] When the shield element 116 is implemented as a single-hole aperture (see FIG. 4(A)), for example, the side walls of the individual through openings 118 are correspondingly formed to achieve the same effect. As an example, the side walls of the through opening 118 form a cone (not shown).

[0157] FIG. 6 schematically shows a further exemplary embodiment of a shield element 116, which is implemented in the same way as that of FIG. 4(F) but differs in that one of the through openings 118 has a certain geometric feature. In this example, the through opening 118 * comprises two adjacent through openings 118, with the web 119 removed therebetween. This through opening 118 *Therefore, it can be clearly distinguished from other through openings 118, and thus the orientation can be set. In particular, the through opening 118 * Advancing from, it is possible to find the central through opening 118 closest to the sample stage 120 (see FIGS. 1-3, 5, 7, 8, 10, or 12).

[0158] FIG. 7 shows a schematic diagram of a third exemplary embodiment of an apparatus 100 for analyzing and / or processing a sample 200 (see FIGS. 2, 3, or 12) with a particle beam 112. Unless otherwise described below, the apparatus 100 of FIG. 7 may have the same features as any of the apparatuses 100 of FIGS. 1, 2, or 3.

[0159] In this example, the supply unit 110 includes a beam guiding element 113 disposed between the shield element 116 and the beam generation unit 111. The voltage source U0 is configured to apply a specific acceleration voltage between the beam generation unit 111 and the beam guiding element 113. The charged particles of the particle beam 112 are thus accelerated in the direction of the beam guiding element 113.

[0160] The shield element 116 is held, for example, in a manner insulated from the supply unit 110. A further voltage source U1 is configured to apply a voltage between the beam guiding element 113 and the shield element 116. As a result, an electric field (not shown) is formed between the beam guiding element 113 and the shield element 116. This electric field is controllable by the voltage applied by the further voltage source U1. Thus, in the region between the beam guiding element 113 and the shield element 116, the particle beam 112 can be guided, in particular accelerated or decelerated and / or deflected. The same applies to charged particles emitted from the sample 200 and passing through the shield element 116 opposite to the beam direction. It can also be said that the beam guiding element 113 forms an electro-optical element together with the shield element 116 and the voltage source U1.

[0161] As an alternative to the figure of FIG. 7, a further voltage source U1 can be arranged, for example, between the beam guiding element 113 embodied as a pole piece and the shield element 116.

[0162] FIG. 8 shows a schematic view of a fourth exemplary embodiment of an apparatus 100 for analyzing and / or processing a sample 200 (see FIGS. 2, 3, or 12) with a particle beam 112. The apparatus 100 of this example has the same structure as the apparatus 100 of FIG. 7. However, the shield element 116 is here additionally held by a holding device 116 * The holding device 116 * is embodied here as a separate element, and the shield element 116 is electrically insulated from the holding device 116 * An additional voltage source U2 is configured to apply a voltage between the beam guiding element 113 and the holding device 116 * Two electric fields (not shown) are arranged side by side along the beam direction, and the particle beam 112 passes through them, whereby the particle beam 112 can be influenced. A number of different electric field configurations can be set using this structure.

[0163] As an alternative to the structure shown, the additional voltage source U2 can also be arranged between the holding device 116

[0164] and the shield element 116. * As a further alternative, a voltage source U1 is arranged between the holding device 116

[0165] and the beam guiding element 113, and an additional voltage source U2 is arranged between the holding device 116 * and the shield element 116. * FIG. 8 further shows a current measurement device I1 configured to detect a current flowing away from the shield element 116. The current measurement device I1 can be used as a detector in various ways. In particular, between the shield element 116 and the holding device 116

[0166] and the holding device 116 *Also, in cooperation with a voltage applied between the beam guiding element 113 and acting as an energy filter, it is possible to distinguish, for example, secondary electrons having low energy in the range of several electron volts to several tens of electron volts from backscattered electrons having higher energy within the range of the beam energy. The shield element 116 can in that case be used, for example, as a secondary electron detector.

[0167] Furthermore, the gas pressure in the region of the shield element 116 can be estimated from the detected current, because there is a positive correlation between the gas pressure and the current. When the gas pressure increases, more collisions occur between the particles of the particle beam and the gas molecules, and thus more extensive scattering occurs. As a result, the number of particles scattered to the shield element 116 increases, and thus the detected current also increases.

[0168] FIG. 9 schematically shows a further exemplary embodiment of the shield element 116, here comprising eight insulated sections Ia, Ib, IIa, IIb, IIIa, IIIb, IVa, IVb, each adjacent to a through-opening 118. Voltages can be applied to each pair of these sections facing each other, i.e., Ia-Ib, IIa-IIb, IIIa-IIIb, IVa-IVb, by controllable voltage sources UI, UII, UIII, UIV respectively assigned to this pair. By this shield element 116 forming a beam deflection element, it is possible to realize additional control with respect to the particle beam 112 (see FIGS. 1-3, 7, 8, 10, or 12).

[0169] FIG. 10 schematically shows an excerpt from a further exemplary embodiment of an apparatus 100 (see FIGS. 2, 3, or 12) for analyzing and / or processing a sample 200 with a particle beam 112. Unless otherwise described below, the apparatus 100 of FIG. 10 can have the same features as the apparatus 100 of any of FIGS. 1-3, 7, or 8.

[0170] A special feature of this exemplary embodiment is that two shield elements 116 are arranged side by side along the beam direction, and both of the shield elements cover the opening 114. In this case, one of the shield elements 116 is held by the positioning unit 140. Thus, this shield element 116 can be displaced relative to the shield element 116 fixedly arranged above it. In this way, the two shield elements 116 form an adjustable aperture. The positioning unit 140 particularly comprises one or more curved portions and / or piezoelectric actuators. Thereby, the shield element 116 is displaceable along at least one axis. Preferably, the shield element 116 is displaceable along at least two axes. Additionally and / or alternatively, the shield element 116 can be held in a rotatable manner.

[0171] FIG. 11 shows a schematic block diagram of one exemplary embodiment of a method for analyzing and / or processing a sample 200 (see FIGS. 2, 3, or 12) with a particle beam 112 (see FIGS. 1 - 3, 7, 8, 10, or 12). The method is preferably carried out by one of the apparatuses 100 of FIGS. 1 - 3, 7, 8, 10, or 12.

[0172] In a first step S1, the sample 200 is placed on the sample stage 120. This includes positioning the sample 200 below the shield element 116 (see FIGS. 1 - 10, or 12) such that, for example, the through - opening 118 (see FIGS. 1 - 10, or 12) is directly above the processing position 202 (see FIGS. 2, 3, or 12) on the sample 200.

[0173] In a second step S2, the particle beam 112 is supplied, and in a third step S3, the particle beam 112 is radiated through the through - opening 118 onto the processing position 202 on the sample 200, and in this way the sample 200 is analyzed and / or processed.

[0174] FIG. 12 shows a schematic view of a further exemplary embodiment of an apparatus for analyzing and / or processing a sample 200 with a particle beam 112. Unless otherwise described below, the apparatus 100 of FIG. 12 may have the same features as the apparatus 100 of any of FIGS. 1-3, 7, 8, or 10.

[0175] In this exemplary embodiment, the apparatus 100 is configured to establish electrical contact with the sample 200 by means of a convex section 117 of the shield element 116. This can be particularly advantageous in the case of a sample 200 having a conductive surface, because the charge can flow directly away from the surface of the sample, and as a result, no disturbing electric field is formed. In particular, in this exemplary embodiment, before bringing the sample 200 into contact with the shield element 116, a protective layer 204 is deposited around the processing position 202 on the surface of the sample by a particle beam induced process. In particular, the deposition process is carried out by the apparatus 100. For this purpose, for example, molybdenum hexacarbonyl Mo(CO) 6 is used as the process gas PG (see FIGS. 2 or 3). The protective layer 204 thus produced has advantageous conductivity and also serves as protection against mechanical damage to the sample 200 caused by the shield unit 116 when the shield unit 116 is in contact with the sample 200. After completion of the analysis or processing, the protective layer 204 can be removed again, for example, by a particle beam induced etching process.

[0176] FIG. 13 shows an excerpt from a schematic view of an eighth exemplary embodiment of an apparatus 100 for analyzing and / or processing a sample 200 with a particle beam 112. Unless otherwise described below, the apparatus 100 of FIG. 13 may have the same features as the apparatus 100 of any of FIGS. 1-3, 7, 8, 10, or 12.

[0177] In this example, the supply unit 110 includes a gas supply unit 130 configured to feed a process gas PG through a through-opening 118 of a shield element 116 to a processing position 202 on a sample 200. The process gas PG flows through the through-opening 118 along the beam direction of the particle beam 112 and thus reaches the processing position 202 on the sample 200.

[0178] When using this configuration of the gas supply unit 130, there is a risk that the process gas PG also flows in a direction opposite to the beam direction towards the beam generation unit 111 (see FIGS. 1, 7, or 8), for example, and reacts chemically with elements in the supply unit 110. Thus, in this example, the aperture 132 is provided above the nozzle or the outlet of the gas supply unit 130. The aperture 132 has a through-opening for the particle beam 112. The aperture 132 prevents a free gas flow from flowing upward in a direction opposite to the beam direction.

[0179] At the same time, a potential can be applied to the aperture 132, whereby the aperture 132 can be used for beam guidance and / or otherwise as a detector. In addition to the aperture 132, differential pump stages can be provided (not shown), which further reduce the upward gas flow in a direction opposite to the beam direction.

[0180] FIGS. 14A to 14D each show a cross-section through a shield element 116 in a plurality of different embodiments. Each shield element 116 illustrated in these figures can be used in particular with the device 100 of FIGS. 1 to 3, 7, 8, 10, 12, or 13.

[0181] The shield elements 116 illustrated in FIGS. 14A to 14D all have a planar section 116A from which a convex section 117 extends. The shield elements 116 illustrated herein have different geometries, particularly of their respective convex sections 117. However, it should be noted that the planar section 116A is not an essential feature of the shield element 116. In a plurality of embodiments (not shown), the shield element 116 does not comprise a planar section 116A. In further embodiments, the shield element 116 consists of a convex section 117.

[0182] The shield element 116 illustrated in FIG. 14A has a hemispherical convex section 117, in which case the through-opening 118 is located at the deepest point of this hemisphere. It should be noted that the convex section 117 does not have to constitute a complete hemisphere. In further embodiments, the convex section 117 constitutes a smaller section on a spherical surface. Furthermore, the shape does not have to be strictly spherical, and there may rather be a deviation therefrom, for example when the shape is compressed or stretched.

[0183] FIG. 14B shows a shield element 116 which is geometrically identical to that shown in FIG. 14A but has an additional opening (not reference numeraled) in addition to the through-opening 118. It can also be said that the convex section 117 of the shield element 116 is embodied as a mesh body.

[0184] The shield element 116 illustrated in FIG. 14C has a convex section 117 in the form of a paraboloid of revolution, and the through-opening 118 is located at the deepest point of the paraboloid of revolution.

[0185] The shield element 116 illustrated in FIG. 14D has a convex section 117 in the form of a cone, in which case the through-opening 118 is located at the apex of the cone.

[0186] It should be noted that each shield element 116 illustrated in FIGS. 4(A) to 4(F), FIG. 6, or FIG. 9 can be made into the shape as illustrated with reference to FIGS. 14A to 14D. In other words, each of the shield elements 116 illustrated in FIGS. 14A to 14D may also have the same additional features of the shield element 116 described with reference to FIGS. 4(A) to 4(F), FIG. 6, or FIG. 9.

[0187] The embodiments illustrated in FIGS. 14A to 14C are examples of the convex section 117 that is strictly convex according to the mathematical definition. The term "convex" will be described based on an illustrative example with reference to FIG. 15.

[0188] FIG. 15 shows a schematic diagram for explaining the term "convex". FIG. 15 shows a curve 117 representing, for example, a cut edge of a cross section passing through the convex section 117. Two points P1 and P2 on the curve 117 are emphasized. A connecting straight line LIN between these two points P1 and P2 is further illustrated.

[0189] The curve 117 is convex, which can be recognized from the fact that, for example, as illustrated with respect to two points P1 and P2 in FIG. 15, the connecting straight line LIN for any random pair of points P1 and P2 on the curve 117 exists outside the curve 117.

[0190] Although the present invention has been described based on exemplary embodiments, the present invention can be modified in various ways. In particular, the features and aspects described in the various exemplary embodiments can be combined with each other, and this also applies even when it is not explicitly stated as such in the corresponding descriptions of the exemplary embodiments.

Description of Reference Numerals

[0191] 100 Device 110 Supply Unit 111 Beam Generation Unit 112 Particle Beam 113 Beam Guidance Element 114 Aperture 116 Shield element 116 * Retention device 116A Planar region 117 Convex section 118 Through-opening 118 * Through-opening 118A Cross-sectional area 118B Cross-sectional area 119 Web 120 Sample stage 130 Gas supply section 132 Aperture 140 Positioning unit 200 Sample 202 Processing position 204 Protective layer Α Opening angle E Electric field I1 Current measurement device Ia Section Ib Section IIa Section IIb Section IIIa Section IIIb Section IVa Section IVb Section LIN Connection straight line P1 Point P2 Point PG Process gas Q Charge S1 Step of method S2 Step of method S3 Step of method U0 Voltage source U1 Voltage source U2 Voltage source UI Voltage source UII Voltage source UIII Voltage source UIV Voltage source

Claims

1. An apparatus (100) for analyzing and / or processing a sample (200) with a particle beam (112), wherein the sample (200) is a lithography mask, and the apparatus (100) comprises: a sample stage (120) for holding the sample (200); a supply unit (110) for supplying the particle beam (112); an aperture (114) for guiding the particle beam (112) to a processing position (202) on the sample (200); and a shield element (116) for shielding an electric field (E) generated by a charge (Q) accumulated on the sample (200), wherein the shield element (116) covers the aperture (114), is embodied in a sheet-like manner, and contains a conductive material; wherein the shield element (116) comprises a convex section (117), and the section is convex with respect to the sample stage (120) so as to project in the direction of the sample stage (120); wherein the convex section (117) has a through-opening (118) for the particle beam (112) to pass through to the sample (200), and a supply unit (110); wherein the apparatus (100) is configured such that, during analysis or processing of the sample (200) by the particle beam (112), the convex section (117) of the shield element (116) is at a maximum distance of 500 μm from the sample (200).

2. The apparatus according to claim 1, further comprising a gas supply unit (130) configured to feed a process gas (PG) through the through-opening (118) of the shield element (116) to the processing position (202) on the sample (200).

3. The apparatus according to claim 1 or 2, further comprising a gas supply unit (130) configured to feed a process gas (PG) into a gap, the gap being formed by the sample (200) disposed on the sample stage (120) and the shield element (116).

4. The apparatus according to claim 2 or 3, wherein the gas supply unit (130) comprises a supply channel incorporated in the shield element (116).

5. The apparatus according to any one of claims 1 to 4, wherein the through-opening (118) includes a point where the distance between the shield element (116) and the sample stage (120) is the smallest.

6. The device according to any one of claims 1 to 5, wherein the shield element (116) comprises a planar section (116A) from which the convex section (117) extends in the direction of the sample stage (120).

7. The device according to any one of claims 1 to 6, wherein the convex section (117) is embodied in a funnel-shaped manner, in particular having a circular cross-section.

8. The device according to any one of claims 1 to 7, wherein the convex section (117) comprises a section that is strictly convex, a spherical surface, and / or a section with a spherical surface.

9. The device according to any one of claims 1 to 8, wherein the convex section (117) of the shield element (116) is embodied in such a manner that a connecting line (LIN) connecting two points (P1, P2) on the surface of the convex section (117) of the shield element (116) is present outside the shield element (116) for any combination of the two points (P1, P2) on the surface of the convex section (117) of the shield element (116).

10. The device according to any one of claims 1 to 9, wherein the shield element (116) comprises a layer made of a conductive material on its surface, and the layer thickness of the layer is greater than or equal to the penetration depth of the particles of the particle beam (112) into the material.

11. The device according to any one of claims 1 to 10, wherein the shield element (116) has exactly one through-opening (118).

12. The device according to any one of claims 1 to 11, wherein the shield element (116) has a plurality of through-openings (118) separated from each other by webs (119).

13. The device according to claim 12, wherein each of the through-openings (118) has a hexagonal cross-section.

14. The device according to claim 12 or 13, wherein the web (119) is shaped such that the sample stage-side cross-sectional area (118A) of each one of the plurality of through-openings (118) in a first plane perpendicular to the surface normal (N) of the shield element (116) above the through-openings (118) is smaller than the opening-side cross-sectional area (118B) of the corresponding through-opening (118) in a second plane parallel to the first plane.

15. The device according to any one of claims 12 to 14, wherein one of the plurality of through openings (118) has a geometric feature that distinguishes the through opening (118) from further said through openings (118).

16. The device according to any one of claims 12 to 15, wherein one of the plurality of through openings (118) includes a point where the distance between the shield element (116) and the sample stage (120) is minimum, and further said through openings (118) are arranged symmetrically with respect to said one through opening (118).

17. The device according to any one of claims 1 to 16, comprising: a beam generation unit (111); and a beam guiding element (113) arranged between the beam generation unit (111) and the shield element (116) and configured to guide the particle beam (112), wherein a voltage source (U1) for applying a voltage between the shield element (116) and the beam guiding element (113) is provided.

18. The shielding element (116) is fixed to the supply unit (110) by a holding device (116 * ), and the holding device (116 * ) and the shielding element (116) are electrically insulated from each other, and a further voltage source (U2) is provided for applying a voltage between the holding device (116 * ) and the beam guiding element (113) and / or the shielding element (116). The device according to claim 17.

19. The device according to any one of claims 1 to 18, wherein the shield element (116) is held in an electrically insulated manner and includes a detection unit (I1) for detecting a current flowing away from the shield element (116).

20. The device according to any one of claims 1 to 19, wherein the shield element (116) includes a plurality of sections (Ia, Ib, IIa, IIb, IIIa, IIIb, IVa, IVb) that are electrically insulated from each other and define the through openings (118), and in any case where they are arranged opposite to each other, a voltage can be applied between two sections (Ia, Ib, IIa, IIb, IIIa, IIIb, IVa, IVb) by corresponding voltage sources (UI, UII, III, UIV).

21. The device according to any one of claims 1 to 20, wherein a plurality of shield elements (116) are arranged one by one along the beam direction and cover the opening (114), and at least one of the plurality of shield elements (116) is held in a displaceable manner for the purpose of providing an opening with an adjustable aperture value.

22. A combination of the device according to any one of claims 1 to 21 and a sample (200), wherein the sample (200) is a lithography mask, the combination of the device according to any one of claims 1 to 21 and the sample (200).

23. A method for analyzing and / or processing a sample (200) with a particle beam (112) by means of the device (100) according to any one of claims 1 to 21, wherein the sample (200) is a lithography mask, and the method comprises a step (S1) of placing the sample (200) on the sample stage (120); a step (S2) of supplying the particle beam (112); a step (S3) of irradiating the particle beam (112) through the through-opening (118) onto the processing position (202) on the sample (200).

Images