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

Abstract

Device (100) for analyzing and / or processing a sample (10) with a particle beam (110), comprising: a provisioning unit (106) for providing the particle beam (110); a shielding element (202) for shielding an electric field (E) generated by charges (Q) accumulated on the sample (10) when the shielding element (202) is located at a distance of at most 100 µm from the sample (10), wherein the shielding element (202) has a passage opening (206) for the particle beam (110) to pass through to the sample (10); a detection unit (112) which is designed to detect the actual position of the shielding element (202); an adjustment unit (600) for adjusting the shielding element (202) from the actual position to a target position; and a fastening device (310) for frictionally fastening the shielding element (202), wherein the adjustment unit (600) is configured to move the shielding element (202) from its actual position to its desired position by overcoming the frictional engagement.

Description

[0001] The present invention relates to a device for analyzing and / or processing a sample with a particle beam and a corresponding method.

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system, which includes an illumination system and a projection system. The image of a mask (reticule) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0003] The mask, or lithography mask, is used for a multitude of exposures, making its defect-free condition of paramount importance. Consequently, considerable effort is invested in examining lithography masks for defects and repairing any identified flaws. Defects in lithography masks can be on the order of a few nanometers. Repairing such defects requires equipment that offers very high spatial resolution for the repair process.

[0004] Devices that activate local etching or deposition processes based on particle beam-induced processes are suitable for this purpose.

[0005] EP 1 587 128 B1 discloses such a device, which uses a beam of charged particles (“particle beam”), in particular an electron beam from an electron microscope, to trigger the chemical processes. When using charged particles, the sample can become charged if it is non-conductive or only poorly conductive. This can lead to uncontrolled beam deflection, which limits the achievable process resolution. Therefore, it is proposed to arrange a shielding element very close to the processing position, so that the charging of the sample is minimized and the process resolution and control are improved.

[0006] In particular, an electron microscope is known with a shielding element in the form of a metallic shielding element, which is located, for example, 70–80 µm above the mask. The shielding element typically has openings, such as round, rectangular, or hexagonal meshes, and is held in the desired position by a holder. The holder is an integral part of the component, which also incorporates the electrostatic deflection system and the gas supply. The particle beam is to be guided along the optical axis of the electron microscope through a specific opening in the shielding element. Until now, this has required a complex adjustment of the shielding element, in which a vacuum is first created, the position of the shielding element is determined with the electron microscope, and the holder, along with the mesh, is then manually moved after the vacuum is broken.This process is repeated until the corresponding opening is in the appropriate position.

[0007] US 2010 / 0119698 A1 discloses a device for producing a miniaturized object using an electron beam and suitable reactive process gases. A shielding element is provided for shielding charges accumulated on the sample directly above it. During operation of the device, the electron beam passes through the shielding element.

[0008] US 2001 / 0002697A1 discloses an electron microscope particularly suitable for examining a sample with material contrast to detect defects in the sample. For this purpose, the secondary electron signal from secondary electrons emitted by the materials is used. The yield of secondary electrons, and thus also the contrast between different materials, depends strongly on an electric field near the sample. The electric field can accelerate or decelerate the secondary electrons, with an accelerating field improving the yield. Therefore, it is proposed to position a grid above the sample, which is set to a positive potential relative to the sample.

[0009] US 2002 / 0148960A1 discloses an electron microscope for examining samples, particularly samples made of insulating material. It is proposed to arrange a shielding electrode between an electron-optical objective and the sample, whereby the shielding electrode can be subjected to a potential relative to the sample stage. In this way, a higher accelerating voltage for the electron beam can be used, which is why the electron microscope can exhibit higher resolution.

[0010] The article by N. Okai et al., “Study on image drift induced by charging during observation by scanning electron microscope,” published in the Japanese Journal of Applied Physics 51 (2012), describes simulations for determining image drift that can occur when using electron microscopes at the interface between conductive and insulating materials of a sample due to charging of the insulating material. It is explained that the occurrence of image drift can be avoided by applying a bias voltage between the anode of the electron microscope and the sample.

[0011] WO 2005 / 101451A1 discloses a device for examining and / or modifying a sample using charged particles. The device comprises a beam of charged particles and a shielding element with an opening for allowing the beam of charged particles to pass through. The opening is sufficiently small and the shielding element is positioned sufficiently close to the surface of the sample to reduce the influence of charge accumulation effects at the surface on the beam of charged particles.

[0012] WO 2018 / 025849 A1 discloses a device for providing a beam of charged particles comprising an electron source, a sample stage, a shielding electrode, and a potential electrode. A potential difference is applied between the sample stage and the potential electrode. Furthermore, an electric potential is applied to the shielding electrode to reduce the electric field caused by the potential difference in the sample.

[0013] Against this background, one object of the present invention is to provide an improved device for analyzing and / or processing a sample with a particle beam and an improved method.

[0014] According to a first aspect, a device for analyzing and / or processing a sample with a particle beam is proposed. The device comprises: a provisioning unit for providing the particle beam; a shielding element for shielding an electric field generated by charges accumulated on the sample, wherein the shielding element has a passage opening for the particle beam to pass through to the sample; a detection unit which is designed to detect the actual position of the shielding element; and an adjustment unit for moving the shielding element from the actual position to a target position.

[0015] This device offers the advantage that the adjustment unit allows for semi- or fully automated adjustment of the shielding element's position. In particular, this eliminates the need for manual adjustment. The vacuum also no longer needs to be broken. A particularly advantageous feature is that the shielding element's position can be monitored by the detection unit during the entire adjustment process or parts thereof. This preferably eliminates the iterative process known from the prior art.

[0016] The sample is, for example, a lithography mask with a feature size in the range of 10 nm to 10 µm. It could be, for instance, a transmissive lithography mask for DUV lithography (DUV: "deep ultraviolet," working light wavelengths in the range of 30–250 nm) or a reflective lithography mask for EUV lithography (EUV: "extreme ultraviolet," working light wavelengths in the range of 1–30 nm). The analysis includes, in particular, imaging of the sample surface using the particle beam. The processing performed using the particle beam includes, for example, etching processes in which material is locally removed from the sample surface, deposition processes in which material is locally applied to the sample surface, and / or similar locally activated processes, such as the formation of a passivation layer or the compaction of a layer.

[0017] The particle beam consists of charged particles, such as ions, electrons, or positrons. The delivery unit is, for example, an electron column capable of providing an electron beam with an energy in the range of 10 eV to 10 keV and a current in the range of 1 µA to 1 pA. Alternatively, it can be an ion source providing an ion beam. The particle beam is preferably focused onto the sample surface, achieving, for example, an irradiation zone with a diameter in the range of 1 nm to 100 nm. The particle beam of charged particles can be manipulated by electric and magnetic fields, i.e., accelerated, steered, shaped, and / or focused. For this purpose, the delivery unit can include a number of elements configured to generate the corresponding electric and / or magnetic field.These elements are arranged in particular between the beam generating unit and the shielding element.

[0018] The shielding element serves to shield, i.e., spatially confine, the electric field of the charges that have accumulated on the sample, particularly to the smallest possible gap between the shielding element and the sample. For this purpose, the shielding element comprises an electrically conductive material. The shielding element may, for example, contain a precious metal. For instance, the shielding element may contain at least one element from the list including gold, nickel, palladium, platinum, and iridium. In some embodiments, the shielding element is made of gold. For example, the shielding element is grounded so that charges falling onto it are dissipated. The shielding element effectively shields the electric field of charges on the sample in a region of space above the shielding element, from where the particle beam originates.

[0019] The shielding element itself can be planar, preferably having a three-dimensional shape whose surface has a convex section facing a sample stage for holding the sample. The convex section preferably forms the section closest to the sample stage, meaning that the distance between the sample stage or the sample and the shielding element is smallest in the region of the convex section. The convex section extends, for example, over a distance of at least 100 µm, preferably at least 250 µm, and more preferably at least 500 µm, towards the sample stage. Preferably, the difference between the distance of the point closest to the sample stage of the shielding element and the distance of the point furthest from the sample stage is at least 100 µm, preferably at least 250 µm, and more preferably at least 500 µm.In the convex section, the shielding element can have the opening through which the particle beam passes and illuminates the sample. The shielding element can be arranged to close an opening in the delivery unit through which the particle beam is guided to a processing position on the sample and / or form the component of the delivery unit closest to the sample stage in the beam direction.

[0020] The shielding element, in particular its convex section, maintains a distance from the sample of at most 100 µm, preferably at most 50 µm, more preferably at most 25 µm, and further preferably at most 10 µm, during analysis or processing of the sample with the particle beam. The smaller the distance, the less an electric interference field can influence the particle beam.

[0021] This allows the particle beam to be precisely controlled and is less susceptible to random and / or uncontrollable disturbances. High resolution is therefore possible, both in image acquisition, as in a scanning electron microscope, and in processing methods performed with the particle beam, such as particle beam-induced etching or deposition processes, ion implantation, and / or other structure-modifying processes.

[0022] The shielding element, for example, has a length and width in the range of 1 mm to 50 mm. The material thickness of the shielding element is, for example, in the range of 1 µm to 100 µm, preferably 5 µm to 15 µm. The opening, for example, has a cross-sectional area in the range of 100 µm. 2 - 2500 µm 2 preferably between 400 µm 2 - 1600 µm 2 , preferably between 750 µm 2 - 1400 µm 2The passage opening has, for example, a diameter in the range of 10 µm to 50 µm, preferably between 20 µm and 40 µm, and more preferably between 25 µm and 35 µm. The diameter refers, for example, to the distance between two opposite points of the passage opening.

[0023] Any type of sensor can be used as the detection unit. In particular, an electron microscope, as explained below, is suitable. Alternatively, the sensor can be optical, inductive, or capacitive. Preferably, the detection unit detects both the actual position before adjustment and the new actual position after adjustment (which corresponds to the target position or an intermediate position between the actual and target positions of the shielding element). The detection unit can be configured to sample the respective actual position of the shielding element at a sampling rate of, for example, greater than 1, greater than 10, or greater than 100 Hz. The actual and / or target position can each be detected relative to an optical axis of the delivery unit.

[0024] The adjustment unit can have one or more motors or actuators. The motors can be electric motors, the actuators electromagnetic actuators.

[0025] In particular, a regulation can be provided such that the adjustment unit adjusts the shielding element depending on the actual position of the shielding element (possibly at a respective sampling time).

[0026] Furthermore, the device can have a gas supply which is set up to supply a process gas into a gap, wherein the gap is formed by the sample arranged on the sample table and the shielding element.

[0027] The process gas flows through the gap to the processing position on the sample. The supply unit, for example, has a flushing plate encompassing the opening for the particle beam. The gas is supplied, for example, through the flushing plate.

[0028] Suitable process gases for material deposition or the growth of raised structures in conjunction with the particle beam include, in particular, alkyl compounds of main group elements, metals or transition elements. Examples include cyclopentadienyl trimethylplatinum CpPtMe3 (Me = CH4), methylcyclopentadienyl trimethylplatinum MeCpPtMe3, tetramethyltin SnMe4, trimethylgallium Ga-Me3, ferrocene Cp2Fe, bis-aryl chromium Ar2Cr, 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 Co2(CO)8, triruthenium dodecacarbonyl Ru3(CO)12, iron pentacarbonyl Fe(CO)5, and / or alkoxide compounds of main group elements, metals, or transition elements, such as tetraethyl orthosilicate Si(OC2H5)4, tetraisopropoxytitanium Ti(OC3H7)4and / or halide compounds of main group elements, metals or transition elements, such as tungsten hexafluoride WF6, tungsten hexachloride WCl6, titanium tetrachloride TiCl4, boron trifluoride BF3, silicon tetrachloride SiCl4, and / or complexes with main group elements, metals or transition elements, such as copper bis-hexafluoroacetylacetonate Cu(C5F6HO2)2, dimethyl gold trifluoroacetylacetonate Me2Au(C5F3H4O2), and / or organic compounds such as carbon monoxide CO, carbon dioxide CO2, aliphatic and / or aromatic hydrocarbons, and the like.

[0029] Examples of process gases suitable for etching materials in conjunction with the particle beam include: xenon difluoride XeF₂, xenon dichloride XeCl₂, xenon tetrachloride XeCl₄, water vapor H₂O, heavy water D₂O, oxygen O₂, ozone O₃, ammonia NH₃, nitrosyl chloride NOCl, and / or one of the following halide compounds: XNO, XONO₂, X₂O, XO₂, X₂O₄, X₂O₆, where X is a halide. Further process gases for etching materials are specified in the applicant's US patent US 2012 / 0273458A1.

[0030] Additive gases, which can be mixed with the process gas in certain proportions to better control the processing, include, for example, oxidizing gases such as hydrogen peroxide (H₂O₂), nitrous oxide (N₂O), nitrogen oxide (NO₂), nitrogen dioxide (NO₂), nitric acid (HNO₃), and other oxygen-containing gases; and / or halides such as chlorine (Cl₂), hydrogen chloride (HCl), hydrogen fluoride (HF), iodine (I₂), hydrogen iodide (HI), bromine (Br₂), hydrogen bromide (Hbr), phosphorus trichloride (PCl₃), phosphorus pentachloride (PCl₅), phosphorus trifluoride (PF₃), and other halogen-containing gases; and / or reducing gases such as hydrogen (H₂), ammonia (NH₃), methane (CH₄), and other hydrogen-containing gases. These additive gases can be used, for example, in etching processes, as buffer gases, as passivating agents, and for similar applications.

[0031] In embodiments, adjusting the shielding element and / or the holder, which will be explained in more detail later, changes the supply of process gas in relation to the processing point.

[0032] According to one embodiment, the device has a vacuum housing for providing a vacuum within it, wherein at least the shielding element and the adjustment unit are arranged in the vacuum housing.

[0033] This provides a simple solution where the vacuum does not need to be broken to adjust the position of the shielding element. The residual gas pressure in the vacuum housing, when a vacuum is applied—especially without the presence of process gases—is preferably between 2 × 10⁻⁶. -07 and 4×10 -07 mbar, preferably 3×10 -07 mbar.

[0034] The device preferably comprises a sample stage for holding the sample. Preferably, the sample stage is arranged within the vacuum housing. The device includes, for example, a positioning unit for positioning the sample stage relative to the delivery unit. The positioning unit can, for example, be configured to move the sample stage along three spatial axes. Additionally, the positioning unit can be configured to rotate the sample stage about at least one of these axes, preferably about at least two of these axes. The sample stage is preferably vibration-isolated and / or actively damped by a holding structure.

[0035] According to one embodiment, the detection unit includes an electron microscope, in particular a scanning electron microscope.

[0036] This allows the position of the shielding element, in particular the position of the through-hole, to be precisely determined. Advantageously, the device intended for the analysis and / or processing of the sample is also used simultaneously as a detection unit for recording the position of the shielding element.

[0037] A fastening device is provided for the friction-fit fastening of the shielding element, wherein the adjustment unit is designed to move the shielding element from its actual position to its target position by overcoming the frictional engagement.

[0038] The fastening device can be provided on the dispensing unit, particularly at its lower end. The fastening device can be formed in one piece or integrally with the dispensing unit. A predefined force must be applied to overcome the frictional connection. In particular, the fastening device can have one or more clamps by means of which the shielding element or a holder that holds the shielding element is clamped against a friction surface (hereinafter also referred to as the "counter-holder surface"). The clamping force results in a frictional force perpendicular to it, which counteracts any displacement of the shielding element or its holder along the friction surface. The friction surface can be an end face of the dispensing unit, which in particular faces the sample stage and / or downwards.

[0039] According to another embodiment, the adjustment unit can be brought into operative contact with the shielding element.

[0040] The functional connection can be such that the adjustment unit acts directly or indirectly on the shielding element. It can also be designed to be permanent or detachable. The functional connection can be, in particular, mechanical and / or electromagnetic. Specifically, the adjustment unit can be detachably connected or connectable to the shielding element or a holder that holds the shielding element for the purpose of adjustment.

[0041] According to a further embodiment, the device has an engagement element and a receiving element which can be detachably brought into engagement with each other to provide the operative connection, wherein the adjusting unit has one of the engagement element and the receiving element and the shielding element or a holder which holds the shielding element has the other of the engagement element and the receiving element.

[0042] The engagement element and the receiving element form a detachably connected positive fit. This allows for particularly simple creation of the functional connection. The positive fit is preferably achieved by moving the engagement element vertically into the receiving element.

[0043] According to another embodiment, the engagement element is designed as a pin and / or the receiving element as a hole, in particular as a hole in the shielding element or the holder.

[0044] In particular, the pin is moved along its longitudinal axis to engage positively in the hole. The pin can have a circular cylindrical outer contour, while the hole can have a corresponding circular inner contour.

[0045] According to a further embodiment, the device has a force transmission element for providing the operative connection between the adjusting unit and the shielding element, wherein the mechanical stability of the force transmission element is selected such that force transmission along the operative connection is limited to a predefined level, wherein the force transmission element in particular has a predetermined breaking point and / or the engagement element forms the force transmission element.

[0046] This ensures that the adjustment unit can move the shielding element within a predefined range, while on the other hand, if the limits of this range (which is determined in particular by stops) are reached and damage to other parts of the device is imminent, the force exerted on these other parts is limited.

[0047] According to a further embodiment, a further detection device is provided which is configured to detect a position of the engagement element in relation to the receiving element.

[0048] This allows the intervention to be carried out in a controlled manner, making this process faster and / or without potential damage to other parts of the device.

[0049] According to another embodiment, the further detection device includes a camera and / or captures an image using a deflecting mirror.

[0050] This makes it particularly easy to observe the intervention element.

[0051] According to another embodiment, the engagement element protrudes from the deflecting mirror. Alternatively, the receiving element could be molded into or penetrate the deflecting mirror.

[0052] This makes it particularly easy to insert the intervention element into the receiving element, because the outer contour of the intervention element and the inner contour of the receiving element can be observed using the deflecting mirror.

[0053] According to another embodiment, the adjustment unit has a sample table for holding the sample and / or a sample.

[0054] Advantageously, the sample table provided by the system is also used as an adjustment unit; that is, the sample table acts directly or indirectly on the shielding element. If necessary, a special sample (so-called service sample) can also be used, which is moved by means of the sample table, with the sample acting directly or indirectly on the shielding element. In particular, the engagement element or the receiving element is permanently attached to the sample table or the sample itself.

[0055] According to another embodiment, the adjustment unit is configured to move the shielding element in a direction transverse to the optical axis of the provisioning unit.

[0056] In principle, adjusting the actual position to the target position can involve positioning the shielding element in up to six degrees of freedom (three rotational and three translational). However, preferably, only a mechanically simple displacement of the shielding element transversely to the optical axis of the delivery unit is provided.

[0057] According to another embodiment, a flushing plate is provided for supplying process gases, wherein the shielding element is detachably attached to the flushing plate in its actual and target positions.

[0058] In particular, the flushing plate may have the fastening device for the detachable fastening of the shielding element or its holder.

[0059] According to a second aspect, a method for setting the position of a shielding element in a device for analyzing and / or processing a sample with a particle beam is provided. The method comprises the following steps: a) Mounting the shielding element in a vacuum housing of the device; b) Creating the vacuum in the vacuum housing; c) Recording the actual position of the shielding element; and d) Adjusting the shielding element from its actual position to a target position under vacuum.

[0060] Advantageously, the vacuum is not broken during steps c) and d). This significantly reduces the adjustment effort. The device can be, in particular, the device described in the first aspect. The steps do not have to be performed in the order specified in a) - d). For example, step c) can be performed before step b).

[0061] Other possible implementations of the invention also include combinations of features or embodiments described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In such cases, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0062] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention will be explained in more detail below with reference to preferred embodiments and the accompanying figures. Fig. Figure 1 shows a schematic view of a first embodiment of a device for analyzing and / or processing a sample with a particle beam; Fig. Figure 2 shows a section of a schematic view of a second embodiment of a device for analyzing and / or processing a sample with a particle beam; Fig. Figure 3 shows a top view of an embodiment of a shielding element; Fig. Figure 4 shows in perspective several components of a third embodiment of a device for analyzing and / or processing a sample with a particle beam; Fig. 5 shows the components from Fig. 4 in a state installed in the device. Fig. Figure 6 shows the device Fig. 5 including a camera directed at a deflecting mirror to illustrate a further embodiment; Fig. Figures 7a) and b) show, by way of example, different positions of the shielding element in the device made of Fig. 5; and Fig. Figure 8 shows several process steps according to one embodiment in a flowchart.

[0063] In the figures, identical or functionally equivalent elements have been labelled with the same reference symbols, unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0064] Fig. Figure 1 shows a schematic view of a first embodiment of a device 100 for analyzing and processing a sample 10. The device 100 has a vacuum housing 102, the interior of which is kept at a specific vacuum by a vacuum pump 104.

[0065] The device 100 is specifically designed for analyzing and processing samples 10, particularly in the form of lithography masks. For example, the device serves as a verification and / or repair tool for lithography masks, especially for lithography masks used in EUV (extreme ultraviolet) or DUV (deep ultraviolet) lithography. A sample 10 to be analyzed or processed is placed on a sample stage 11 within the vacuum housing 102. The sample stage 11 of the device 100 is specifically designed to adjust the position of the sample 10 to within a few nanometers in three spatial directions and three rotational axes.

[0066] The device 100 further comprises a supply unit 106 in the form of an electron column. This includes an electron source 108 for supplying an electron beam 110 (particle beam) and an electron microscope 112, which detects the electrons backscattered from the sample 10. Instead of the electron beam 110, an ion beam could also be supplied. An additional detector for secondary electrons may also be provided (not shown). The electron column 106 preferably has its own vacuum housing 113 within the vacuum housing 102. The vacuum housing 113 is, for example, pressurized to a residual gas pressure of 10 -7 mBar - 10 -8 The room is evacuated to mbar. In this vacuum, the electron beam 110 travels from the electron source 108 until it exits the vacuum housing 113 at its underside and then falls onto the sample 10.

[0067] The electron column 106, in conjunction with supplied process gases introduced externally by a gas supply unit 114 via a gas line 116 into the area of ​​a focal point of the electron beam 110 on the sample 10, can perform electron-beam induced processing (EBIP). This includes, in particular, the deposition of material onto and / or the etching of material from the sample 10. The device 100 also has a control computer 118, which appropriately controls the electron column 106, the sample stage 11, and / or the gas supply unit 114.

[0068] Fig. Figure 2 shows a section of a schematic view of a second embodiment of a device 100 for analyzing and / or processing a sample 10 with a particle beam 110. Unless otherwise described below, the device 100 can be used for... Fig. 2 the same features as device 100 of the Fig. exhibit 1.

[0069] An opening 200 for the electron beam 110 is arranged on the underside of the vacuum housing 113. The opening 200 is partially or completely closed by a shielding element 202. The shielding element 202 is planar and comprises an electrically conductive material, in particular gold. The shielding element 202 may have a convex section 204 with respect to the sample stage 11. The convex section 204 curves towards the sample stage 11. The convex section 204 (or, if no such section is present, generally the shielding element 202) has a passage opening 206 for the electron beam 110 to pass through. The distance of the shielding element 202 from the sample stage 11 is preferably smallest in the region of the passage opening 206.The distance between the passage opening 206 and the sample 10 during operation (analysis / processing of the sample 10) of the device 100 is preferably between 1 µm - 100 µm, preferably between 5 µm - 30 µm and more preferably 10 µm.

[0070] The shielding element 202 is designed to shield an electric field E. To illustrate this, the following are shown in the Fig. Two exemplary charges Q are shown, which generate the electric field E. The charges Q are shown below the shielding element 202, in an area where, when using the device 100, a processing area 208 of the sample 10 is located. Particularly with samples 10 that are electrically non-conductive or only slightly conductive (at least in sections), when the electron beam 110 is directed onto the sample 10, the sample 10 becomes charged and thus the electric field E is generated. In the Fig. Figure 1 shows examples of negative charges Q that are created by irradiating the electron beam 110.

[0071] Shielding the electric field E results in increased accuracy regarding the point of impact and focus position of the electron beam 110 on the sample 10, thus improving resolution and process control. Furthermore, it reduces the influence on the trajectory of backscattered electrons and secondary electrons traveling in the opposite direction to the electron beam 110 towards the electron source 108, which also improves resolution and process control, as well as sensitivity.

[0072] In this example, the supply unit 106 has a gas supply 210, which is configured to supply a process gas PG into a gap 212 between the shielding element 202 and the sample 10. The process gas PG flows along the gap 212 and thus reaches the processing position 208 on the sample 200. The gas supply 210 therefore ensures, on the one hand, a sufficient supply of process gas PG to the processing position 202, and on the other hand, a comparatively low volume flow of the process gas PG through the opening 206 into the supply unit 106, particularly lower than if the process gas PG were fed to the processing position 208 from above through the opening 206.

[0073] Fig. Figure 3 shows an example of a shielding element 202 with a plurality of through-openings 206, of which only one is marked with a reference symbol for clarity. All through-openings 206 have a hexagonal geometry. In this example, several through-openings 206 are also located, at least partially, in the convex section 204.

[0074] Fig. Figure 4 shows in perspective several components of a third embodiment of a device 100 for analyzing and / or processing a sample 10 with a particle beam 110. Fig. Figure 5 shows the components in a state installed in the device 100. Fig. Figure 6 shows the device 100 from Fig. 5 including a camera. Unless otherwise described below, the device can be 100 of the Fig. 4, Fig. 5 to Fig. 6 the same features as the device 100 of the Fig. 1 and Fig. 2 exhibit. The shielding element 202 can be used as in Fig. 3 be trained.

[0075] The shielding element 202 of the Fig. 4 is held by means of a holder 300. The shielding element 202 can be attached to the holder 300, in particular to a ring 302 of the holder (shown only partially visible). Suitable attachment methods include, for example, welding, soldering, or gluing. Alternatively, the shielding element 202 can be integrated into the holder 300, i.e., formed integrally with it.

[0076] According to the exemplary embodiment, the holder 300 has the opening 200 (shown concealed because it is behind the shielding element 202), which is closed by the shielding element 202. The opening 200 can, in particular, be formed within the ring 302.

[0077] The holder 300 can further include the gas supply 210, in particular in the form of openings or holes 304. In the example, four holes 304 are provided, the number of which can vary, in particular, between 2 and 6. The process gas PG is supplied to the processing point 208 via the holes 304 (see Fig. 2) supplied (see Fig. 2) The holes 304 can be formed by connecting the ring 302 to a section 308 of the holder 300 via webs 306. The holder 300 can be made of metal, an alloy, or plastic.

[0078] The holder 300 is frictionally clamped by means of one or more clamps 310 – here, two such clamps 310 are provided. The clamping forces can act, in particular, on the section 308. For example, the clamps 310 can have arms 312 which act on the holder 300 or the section 308. A section of the electron column 106 can – generally speaking – serve as a counter-support surface 314 to generate the clamping effect together with the clamps 310 or their arms 312. In particular, an underside of the vacuum housing 113 serves as the counter-support surface 314. In the exemplary embodiment, a plate attached to or in the area of ​​the underside of the vacuum housing 113, in particular a flushing plate 316, has the counter-support surface 314. The flushing plate 316 has connections 500 (one such connection is shown by way of example) for the process gas PG, which are also located in Fig. Figure 5 shows a simplified representation of the flushing plate 316. The connections 500 are via channels 210 formed in the flushing plate 316 (see Figure 5). Fig. 2) designed to supply the process gas PG, if necessary, through the holes 304 to the processing area 208.

[0079] Alternatively or additionally, the flushing plate 316 (or plate) can have a jet deflection device 216 attached to it or integrated therein (see Fig. 2) exhibit. By means of the beam deflection device 216, the electron beam 110 is deflected for the purpose of processing the processing area 208. The beam deflection device 216 has several, for example, between four and sixteen, preferably six to ten, in particular eight (therefore the beam deflection device 216 is also referred to as an octopole) coils or electromagnets (each not shown because they are obscured), which are arranged around an optical axis 214 of the electron column 106. Current connections 318, one of which is shown by way of example in Fig. As shown in Figure 4, the electromagnets are supplied with electricity.

[0080] The holder 300 together with shielding element 202 is adjustable between an actual position and a target position, i.e. movable, is provided. Fig. Figure 4 shows the actual position. The actual position is detected by a detection unit, which, according to the exemplary embodiment, is formed by the electron microscope 112, which is in particular a scanning electron microscope. This detects the electrons backscattered by the shielding element 202. A corresponding detection image is shown in Fig. 7a) shown, where 206 denotes the aperture which is to be positioned opposite the optical axis 214 of the electron column 106. The optical axis 214 is in the Fig. 1 and Fig. 2 shown collinear with the electron beam 110. The optical axis 214 thus extends in a vertical direction and intersects a center point of the aperture 200.

[0081] In principle, positioning of the holder 300 or the shielding element 202 in all 6 degrees of freedom is conceivable. According to the exemplary embodiment, the positioning only takes place in a plane perpendicular to the optical axis 214, i.e., here in a horizontal direction (xy-plane in Fig. 4) Here, the counter-support surface 314 serves as a sliding or bearing surface, which allows the holder 300 to move horizontally. This sliding movement requires overcoming the frictional force acting between the holder 300 and the counter-support surface 314. The frictional force can be adjusted using screws 320, which hold the clamps 310 to the counter-support surface 314. As shown, the counter-support surface 314 can be recessed into the flushing plate 316, resulting in a rim 322. The rim 322 limits the sliding movement of the holder 300 in the xy-plane, thus forming an end stop for it. A receiving element in the form of a hole 324 is provided on the holder 300 in a tab 326 integrally formed on the holder 300. The plane of the hole is also located in the xy-plane.

[0082] The adjustment of the holder 300 including the shielding element 202 is carried out using a mechanism integrated into the Fig. 6 (partly also in Fig. 5) Adjustment unit 600 shown. According to the exemplary embodiment, the adjustment unit 600 comprises the sample table 11, to which an engagement element 602 is attached, which here is designed in particular as a pin that projects vertically upwards. Alternatively, the pin 602 could also be attached to a sample 10 (so-called service sample) provided specifically for this purpose, which is temporarily arranged on the sample table 11 (namely only for the duration of the adjustment).

[0083] In the exemplary embodiment, the pin 602 is provided to consist of a deflecting mirror 502 (see Fig. 5) protrudes. The deflecting mirror 502 is arranged obliquely to the optical axis 214. For this purpose, it can, for example, be formed on a wedge-shaped or prismatically shaped block 504. The block 504 is in turn attached to the sample stage 11 or the sample 10.

[0084] As in Fig. As shown in Figure 6, a further detection device 606 in the form of a camera is arranged horizontally outside the space 604 between the sample stage 11 and the electron column 106. Using the camera 606 and the deflecting mirror 502, the position of the pin 602 relative to the hole 324 on the tab 324 of the holder 300 can be observed, as indicated by an arrow in Figure 6. Fig. 6 indicated. The sample table 11 is then, for example, controlled using the control computer 118 (see Fig. 1) is appropriately controlled to insert the pin 602 into the hole 324 in a vertical direction. The pin 602 is then moved in the horizontal plane by means of the sample stage 11, which simultaneously causes the holder 300 and the shielding element 202 to move as soon as a predetermined frictional force value is exceeded. This moves the holder 300 and thus the shielding element 202, aligning the through-hole 206 in the shielding element 202 with the one in the Fig. 7b) shown target position moved.

[0085] To prevent damage within the device 100, in particular to the holder 300 or shielding element 202, by means of the pin 602, for example in the event of improper movement thereof, it can be equipped with a predetermined breaking point 506 (see Fig. 5) be provided. The pin 602 breaks off at this point if it, in particular its free tip, is subjected to a force that exceeds a predefined force limit. This is particularly the case if the holder 300 is pushed against the edge 322 by means of the pin 602 (see Fig. 3) is pressed and the applied force exceeds the predefined force limit.

[0086] Fig. Figure 8 shows several process steps according to one embodiment in a flowchart.

[0087] First, when manufacturing a new device 1 or when replacing the shielding element 202 (possibly including holder 300), a new shielding element 202 is mounted on the counter-holder surface 314 (step S1 in Fig. 8) This is done using the clamps 310 and tightening the screws 320. At this point, the vacuum housing 102 is open, i.e., the vacuum in the vacuum housing 102 is broken. The mounting of the holder 300 together with the shielding element 202 can be carried out with the flushing plate 316 removed from the vacuum housing 102, i.e., after the mounting of the holder 300, it is placed back into the vacuum housing 102 and mounted on the electron column 106. Alternatively, the mounting of the holder 300 together with the shielding element 202 takes place in the vacuum housing 102, i.e., on the flushing plate 316 which is already mounted on the electron column 106.

[0088] The vacuum in the vacuum housing 102 is then restored using the vacuum pump 104 (step S2). This means that the holder 300, including the shielding element 202, and the sample stage 11 are in a vacuum.

[0089] In step S3, the actual position of the shielding element 202, in particular the passage opening 206, with respect to the optical axis 214, is determined using the electron microscope 112 (see Fig. 1) recorded.

[0090] Based on a target position of the shielding element 202 provided to or calculated by the control computer 118, this or another computer unit determines a travel path in step S4 along which the sample stage 11 is to be moved in order to appropriately move the shielding element 202 using the pin 602. The sample stage 11 and the pin 602 then move accordingly (step S5). That is, the pin 602 first engages the hole 324 by moving vertically and, if necessary, horizontally. The pin 602 is then moved horizontally to shift the shielding element 202 in the xy-plane and move it from its actual position to the target position. The current actual position is continuously scanned by the electron microscope 112, for example, at a sampling rate of 100 Hz. As soon as the target position is reached, the pin 602 and the hole 324 are disengaged.In particular, the insertion and removal of the pin 602 and the hole 324 is monitored by means of the camera 606, which in embodiments provides corresponding measurement data to the control computer 118 so that the movement of the sample table 11 can be controlled.

[0091] The sample table 11 can then move into a change position (step S6) in which the block 504 along with the pin 602 is removed. This can be done using an automatic tool changer, if necessary.

[0092] Following this – possibly omitting step S6 – the analysis and / or processing of sample 10 in processing area 208 begins in step S7 ( Fig. 2), if necessary without breaking the vacuum provided in step S2 in the meantime.

[0093] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. REFERENCE MARK LIST 10 Sample 11 Sample table 100 Device 102 vacuum housings 104 Vacuum pump 106 electron column 108 electron source 110 electron beam 112 Electron microscope 113 Vacuum housings 114 Gas supply unit 116 Gas pipeline 118 tax calculators 200 opening 202 Shielding element 204 convex section 206 Passage opening 208 processing area 210 Gas supply 212 gap 214 optical axis 216 Beam deflection device 300 holders 302 Ring 304 holes 306 Bridge Section 308 310 terminal 312 Arm 314 Counter-support surface 316 Sink plate 318 Power connection 320 screw 322 Rand 324 holes 326 tab 500 connection 502 Deflection mirrors 504 Block 506 Breakaway point 600 adjustment unit 602 pen 604 space 606 Camera E field lines Q charges x direction y direction

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