Method for producing a micro-optical unit for a multiple particle beam system, micro-optical unit and multiple particle beam system

Abstract

The present invention discloses a method for manufacturing a micro-optical unit for a multi-particle beam system, the method comprising the following steps: (a) providing a first plate of the micro-optical unit, the first plate being conductive; (b) providing a second plate of the micro-optical unit, the second plate being conductive; (c) forming a plate stack comprising stacking the first plate of the micro-optical unit and the second plate of the micro-optical unit on top of each other, wherein the first plate of the micro-optical unit and the second plate of the micro-optical unit are fixed relative to each other in the plate stack and electrically insulated from each other; and (d) penetrating the entire plate stack formed having at least the first plate and the second plate of the micro-optical unit, thereby forming both a first plurality of holes in the first plate of the micro-optical unit and a second plurality of holes in the second plate of the micro-optical unit.

Description

Technical Field

[0001] This invention relates generally to multi-particle beam systems, and more particularly to multi-particle microscopes operating using a plurality of individual charged particle beams. Specifically, this invention relates to a method for manufacturing a micro-optical unit for a multi-particle beam system, a micro-optical unit, and a multi-particle beam system. Prior Technology

[0002] With the continued development of smaller and more complex microstructures, such as those in semiconductor devices, there is a need to further develop and optimize planar manufacturing technologies and inspection systems for manufacturing and inspecting small-sized microstructures. For example, the development and manufacturing of semiconductor components requires monitoring the design of test wafers, and planar manufacturing technologies need process optimization for reliable manufacturing at high throughput. Furthermore, there is a recent demand for the analysis of semiconductor wafers used for reverse engineering and for customized individual configurations of semiconductor components. Therefore, there is a need for inspection components capable of high-throughput operation to inspect microstructures on wafers with high accuracy.

[0003] Typical silicon wafers used to manufacture semiconductor components can reach diameters of up to 300 mm. Each wafer system is divided into 30 to 60 repeating regions (dies), with dimensions up to 800 mm². Semiconductor devices contain multiple semiconductor structures, which are fabricated in multiple layers on the wafer surface using planar integration technology. Due to the manufacturing process, semiconductor wafers typically have planar surfaces. In this case, the structural dimensions of the integrated semiconductor structures extend from a few micrometers to the critical size (CD) of several nanometers, and the structural dimensions will become even smaller in the near future; it is expected that future structural dimensions or critical sizes (CD) will conform to the 3-nanometer, 2-nanometer, or even smaller process technology generations of the International Technology Roadmap for Semiconductors (ITRS). With the aforementioned small structural dimensions, defects on the order of the critical size must be identified rapidly over very large areas. For various applications, the specifications for the measurement accuracy provided by the inspection equipment are even higher, for example, twice or an order of magnitude. For example, the width of semiconductor features must be measured with an accuracy better than 1 nm, such as 0.3 nm or even smaller, and the relative positions of semiconductor structures must be determined with a superposition accuracy better than 1 nm, such as 0.3 nm or even smaller.

[0004] Multi-beam scanning electron microscopy (MSEM) is a relatively recent development in the field of charged particle systems (charged particle microscopy (CPM)). For example, multi-beam scanning electron microscopy is disclosed in documents US7244949B2 and US 2019 / 0355544 A1. In the case of multi-beam electron microscopy or MSEM, a plurality of individual electron beams are simultaneously irradiated by a plurality of individual electron beams arranged in a field or grid. For example, 4 to 10,000 individual electron beams can be provided as primary radiation, with each individual electron beam separated from adjacent individual electron beams by a spacing of 1 to 200 micrometers. For example, an MSEM has approximately 100 individual electron beams (small beams), which are arranged, for example, in a hexagonal grid, with the individual electron beams separated by a spacing of approximately 10 μm. The plurality of individual charged particle beams (primary beams) are focused onto the surface of the sample to be examined through a common objective. For example, the sample can be a semiconductor wafer fixed to a wafer carrier mounted on a movable stage. When a wafer surface is irradiated by a single beam of charged particles, interaction products (e.g., secondary electrons or backscattered electrons) are emitted from the wafer surface. Their initiation points correspond to the locations on the sample where multiple single beams of charged particles are focused in each case. The number and energy of the interaction products depend on the material composition and the wafer surface layout. The interaction products form multiple secondary beams of charged particles, which are focused by a common objective lens and, after passing through a projection imaging system of a multi-beam detection system, are incident on a detector arranged on a detection plane. The detector contains multiple detection regions, each containing multiple detection pixels, and captures the intensity distribution of each secondary beam of charged particles. In this process, an image field of, for example, 100 μm × 100 μm is obtained.

[0005] Existing multibeam electron microscopes include a sequence of electrostatic and magnetic elements. At least some of these electrostatic and magnetic elements can be configured to adjust the focal position and astigmatism of a plurality of individual charged particle beams. Existing multibeam systems with charged particles further include at least one intersecting plane of primary or secondary individual charged particle beams. Furthermore, existing systems include a detection system for ease of setup. State-of-the-art multibeam particle microscopes include at least one deflector (deflection scanner) that scans a sample surface area by focusing a plurality of primary individual particle beams to obtain an image field of the sample surface.

[0006] A beam splitter (or alternative beam splitter or beam splitter) is used to separate the particle optical beam paths of the primary beam from those of the secondary beam. In this case, the separation is achieved through a special configuration of magnetic and / or electrostatic fields, such as through a Wien filter.

[0007] In the case of multi-particle beam systems, there is a fundamental difference between using a single-column system and a multiple-column system. In a single-column system, individual particle beams pass at least partially through the same particle optics unit or through one or more monolithic particle lenses. Furthermore, in a single-column system, the individual particle beams are relatively close to each other. Despite the presence of some monolithic particle optics elements, individual controllability and / or shapeability of the individual particle beams are still required in the single-column case to correct aberrations such as field curvature and field astigmatism. So-called micro-optics units can be used for the individual influence and / or shaping of individual particle beams. Micro-optics units are often also called multi-beam particle generators, used to form and shape multiple individual particle beams. A multi-beam particle generator or micro-optics unit comprises a sequence of multiple porous plates that can be used for active beam shaping, or at least one porous plate can be used for active beam shaping. For example, electrodes that can be collectively or individually controlled can be placed in the regions of the apertures for this purpose. These can be, for example, annular electrodes or multi-electrode electrodes. According to another example, the porous plate can have an integral embodiment in which a voltage is applied uniformly to the porous plate, i.e., the entire porous plate is at a certain potential, so that its openings can form a lens effect when interacting with other particle optics elements. Other configurations of porous plates for active beam shaping are also possible.

[0008] To achieve optimal individual particle beam shaping / individual particle beam influence, the apertures through which the individual particle beams pass must be precisely aligned with each other. For example, the centers of the apertures must be precisely overlapped. Furthermore, the apertures in porous plates are known to be relatively small, for example, each aperture diameter is less than 100 µm, such as only 90 µm or smaller. Both of these conditions—small aperture size and precise aperture / electrode alignment (including control)—can be met by fabricating micro-optical units using MEMS technology. In other words, the fabrication process for micro-optical units or their porous plates is similar to the processes used in semiconductor manufacturing.

[0009] For example, the application of semiconductor components becomes possible by combining regions with different doping properties or by utilizing the effects of insulating layers. To meet these requirements, various layers are sequentially applied onto a disk-shaped base substrate, known as a wafer, during the manufacturing process of semiconductor components (known as a planar process). For example, silicon is used as the base substrate, and silicon oxide, for example, is used as the insulating layer. The applied layers can then be structured using lithography. Thus, integrated circuits with conductor tracks, i.e., semiconductor wafers, or simply micro-optical units with porous plates for multi-particle beam systems, can be formed.

[0010] While MEMS technology offers highly precise fabrication of micro-optical units, it also has drawbacks: the development time for micro-optical units is relatively long, often requiring six to nine months. Changes to the manufacturing process are difficult or time-consuming to implement. Overall, there are very few semiconductor companies involved, semiconductor manufacturing process control is challenging, and semiconductor manufacturing requires extremely expensive equipment. Summary of the Invention

[0011] Therefore, the problem solved by this invention is to provide an improved method for manufacturing micro-optical units for multi-particle beam systems. In particular, this method should be faster than known methods, and especially without sacrificing the quality of the micro-optical units or degrading the achievable resolution in the multi-particle beam system. Furthermore, the method should be easy to implement and cost-effective.

[0012] The aforementioned problems are solved by the technical features of the independent claim. Advantageous embodiments of the invention will be understood from the appendices to the claims.

[0013] This patent application claims priority to German Patent Application No. 10 2023 133 567.7, dated November 30, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0014] This invention is essentially based on two fundamental insights: (1) It has been found that materials used for micro-optical units, such as silicon, can cause serious problems: for example, unwanted surface potentials may occur, and the conductivity of silicon may change over time. Both have adverse effects when individual beams of charged particles pass through the micro-optical unit, thus affecting beam quality and, in turn, the resolution achievable by multi-particle beam systems during their operation. (2) Furthermore, it has been surprisingly found that the expectation / trend to further miniaturize micro-optical units in order to improve resolution is not always correct or necessary. Instead, real advantages are found in fabricating micro-optical units with slightly larger dimensions (e.g., porous plates with larger apertures and / or thicker thicknesses). In particular, there are advantages due to the reduction of parasitic effects (such as reduced beam deflection) while still requiring considerable electro-optical effects, and due to the higher voltage that can be applied to the porous plate of the micro-optical unit. The latter is especially advantageous for increasingly larger individual particle beams and, in the case of micro-optical units, for increasingly larger image fields.

[0015] Therefore, one of the fundamental concepts of this invention is to replace MEMS technology with other manufacturing processes, particularly those applicable to metal processing. In fact, such metal processing processes are often only used to form larger structures, but this is not necessarily a disadvantage. On the contrary, the advantage of metal processing processes is that silicon is no longer required to be used as a material in a quasi-forced manner. In particular, the method according to the invention can also be used to manufacture micro-optical units having one or more porous plates made of metal. Furthermore, with skilled procedures, the problem of precisely aligning the porous plates with each other can be solved, regardless of their material or optical or infrared transmittance; in this case, the porous plates are automatically or inherently aligned correctly with each other.

[0016] According to a first aspect of the present invention, the present invention relates to a method for manufacturing a micro-optical unit for a multi-particle beam system, the method comprising the following steps: (a) A first plate of the micro-optical unit is provided, the first plate being conductive; (b) A second plate of the micro-optical unit is provided, the second plate being conductive; (c) Forming a plate stack, comprising the step of stacking a first plate and a second plate of the micro-optical unit on top of each other, wherein the first plate and the second plate of the micro-optical unit are fixed relative to each other in the plate stack and are electrically isolated from each other; and (d) Penetrating the entire stack of plates having the first and second plates of the micro-optical unit, thereby forming a first plurality of holes in the first plate of the micro-optical unit and a second plurality of holes in the second plate of the micro-optical unit.

[0017] Similar to the introductory section of the description, the term "micro-optical unit" should be understood as referring to a sequence of multiple porous plates, wherein at least one porous plate is used during operation for active beamforming of a plurality of individual particle beams in a multi-particle beam system. Preferably, each of these apertures is through which an exact individual particle beam passes.

[0018] Request 1 does not begin by directly mentioning the porous plate, but rather by referring to the first plate and the second plate of the micro-optical unit. This is because the multiple holes in the first and second plates are formed only during the manufacturing process.

[0019] The first plate of this micro-optical unit is conductive. The conductivity may extend to the entire first plate or only to a portion of it. The same applies to the second plate of the micro-optical unit. This conductivity property contributes to, or is even necessary for, the ability to use many methods known in metal processing in the fabrication of micro-optical units for multi-particle beam systems. This will be explained in detail below.

[0020] The formation of the plate stack includes the step of stacking a first plate and a second plate of the micro-optical unit on top of each other, wherein the first plate and the second plate of the micro-optical unit are fixed relative to each other in the plate stack and electrically isolated from each other. Fixing and electrical insulation can be achieved simultaneously and / or through the same component, but different components can also be used for fixing and electrical insulation. For example, electrically insulating spacers can be used, or a complete electrically insulating plate can be provided.

[0021] The plate stack includes at least a first plate and a second plate of the micro-optical unit. However, the plate stack may also include additional plates of the micro-optical unit. Method step (d) performs the following operation: penetrating the entire plate stack formed with at least the first and second plates of the micro-optical unit, thereby forming a first plurality of holes in the first plate of the micro-optical unit and a second plurality of holes in the second plate of the micro-optical unit. Thus, holes that should be passed through by the same individual particle beam during the operation of the micro-optical unit or multi-particle beam system are formed in the same method step or during the same penetration event. Therefore, when penetration is performed accurately through the drilling member, the mutually distributed hole systems in the first plate and the second plate of the micro-optical unit, as well as selectively in one or more additional plates of the micro-optical unit, are automatically and correctly aligned with each other.

[0022] According to a preferred embodiment of the invention, the first plate and / or the second plate of the micro-optical unit are metals. For example, the metal may be copper, silver, iron, aluminum, tungsten, gold, brass, platinum, stainless steel, or any other metal or metal alloy, or a combination of the above materials. The metal plate itself may also include a surface coating, such as gold plating. Alternatively, the first plate and / or the second plate of the micro-optical unit may also be composed of a semiconductor material. For example, the semiconductor material may include silicon.

[0023] According to another preferred embodiment of the invention, the plate stack further includes at least one additional plate and thus includes at least one third plate of the micro-optical unit, the third plate being conductive. In this case, the third plate of the micro-optical unit is fixed relative to and electrically isolated from the first and second plates of the micro-optical unit in each case. When method step (d) is performed, the third plate of the micro-optical unit is also penetrated, thus creating a third plurality of holes in the third plate of the micro-optical unit. Therefore, the third plurality of holes are also substantially correctly aligned with the other holes of the first and second plates.

[0024] According to a preferred embodiment of the invention, the third plate of the micro-optical unit is made of metal. This also applies to any additional plates that may be present. In principle, all plates of the micro-optical unit can be made of the same material, and in particular, of the same metal; however, this is not necessarily the case.

[0025] According to a preferred embodiment of the invention, the first and / or second and / or third and / or additional plates of the micro-optical unit are magnetically permeable. Additionally, the following relationship (in each case) applies to the relative permeability μr of the plate material: μr ≥ 1000, preferably μr ≥ 10000 or μr ≥ 15000.

[0026] The magnetic permeability of one or more plates, or even all of them, allows for an expansion of the application or potential range of uses of the micro-optical unit. For example, one plate or a sequence of plates in the micro-optical unit is used to set the focus. The magnetic permeable plate, and particularly the final porous plate with respect to the particle optical beam path during operation of the micro-optical unit, can also function as a multi-deflector combined with a downstream magnetic lens: for such applications, the final porous plate is configured or can be configured within the magnetic field of the downstream magnetic lens. Specific configurations of such multi-deflectors will be discussed in more detail in the course of this patent application.

[0027] Various magnetic materials with a relative permeability μr ≥ 1000 exist in the prior art. These include standard soft magnetic materials such as pure iron (e.g., Vacofer®), nickel-iron alloys with approximately 75% nickel content (e.g., Mu Metal), permeable alloys or superpermeable alloys, nickel-iron alloys with approximately 50% nickel content (e.g., Permenorm®), cobalt-iron alloys with approximately 50% cobalt content (e.g., Vacolux®), or silicon-iron alloys with approximately 3% silicon content (e.g., Trafoperm®). These materials are also commercially available as thin films, for example, with thicknesses of 25 μm, 50 μm, 100 μm, or 250 μm. Due to their small thickness, plates made from these materials are, in principle, suitable for use in the method according to the present invention for manufacturing micro-optical units for multi-particle beam systems.

[0028] According to a preferred embodiment of the invention, in step (d), the board stack is penetrated through laser drilling. Laser drilling is a non-mechanical thermal separation method. There are various types of laser drilling technology, such as single-pulse drilling, impact drilling, trephine drilling, and auger drilling. Single-pulse drilling is the fastest; it "penetrates" the material through a single pulse. Impact drilling involves releasing multiple pulses at the same point to laser-perforate the material. Trephine drilling refers to cutting a hole along the drill profile after a through-hole has been formed. Auger drilling may require special optical elements. Fundamentally, the accuracy of the drilling and the smoothness of the hole walls depend on the material being drilled and the type of laser radiation. For example, copper absorbs green and blue radiation well, but not so well with ordinary infrared radiation. Today, laser drilling methods are very fast and very efficient: for example, using single-pulse micro-drilling, 200 holes per second can be drilled on a 1 mm thick titanium plate. For example, the focal diameter of the laser used is 12 micrometers, and the diameter of the resulting hole is only 80 micrometers. When these holes are created using MEMS technology, a hole diameter of 80 μm already corresponds to the size of holes used in prior art. Therefore, laser drilling can be used to create very small holes if needed, and larger holes can be created if necessary through other laser drilling techniques. Furthermore, these methods are very fast. Moreover, as a manufacturing method, laser drilling has the advantage that the material to be drilled does not necessarily have to be metal or even conductive. Insulators can also be penetrated through laser drilling. Therefore, in laser drilling, even a stack of boards with a sequence of conductive and electrically insulating plates can be penetrated immediately, either through the same laser pulse or through multiple identical laser pulses.

[0029] According to another preferred embodiment of the invention, in step (d), the board stack is perforated by micro-discharge machining (Micro-EDM). Micro-discharge machining, or micro-spark erosion, is a form of electrical discharge machining (EDM) and can be described as a combination of drill bit erosion and punch erosion techniques. This technique, using electrical discharge machining erosion as the processing method, is well-suited for high-speed, high-precision machining of conductive materials of varying hardness into the correct shape.

[0030] EDM is a non-contact method that removes material over very short lengths without inducing mechanical stress within it. The material is shaped through highly localized melting and evaporation caused by a discharge between the electrode and the workpiece. The discharge forms tiny plasma channels at temperatures up to 10,000°C, locally melting a very small amount of material. If the current is interrupted, the plasma collapses, and the resulting vacuum pulls the molten material into the surrounding dielectric medium. For the discharge to occur, the material must possess sufficient conductivity; material hardness is not critical. Therefore, all metals and many semiconductors are suitable for EDM, and in principle, micro-EDM is also suitable.

[0031] Micro-discharge machining (MDM) is a special form of electrical discharge machining in which the workpiece can only have features of about 10 µm. These small features are obtained using electrodes that are also very small. Therefore, MDM can also be used to easily obtain holes on the order of those used in micro-optical units. Furthermore, MDM processes are much faster than planar integration techniques.

[0032] According to a preferred embodiment of the invention, in step (d), the stack of boards is perforated by high-speed mechanical micro-drilling. For example, a solid carbide micro-drill bit can be used for this purpose. In this way, drill diameters of several millimeters can be achieved, as well as drill diameters of only 30 μm or even only 10 μm.

[0033] According to a preferred embodiment of the invention, in step (d), the stack of boards is perforated by vibratory drilling or ultrasonic drilling. The principle of vibratory drilling is that, in addition to the feed motion of the drill bit, axial vibration or oscillation is generated, thus breaking down drill chips, which can then be easily removed from the cutting area. There is a difference between self-driven vibration systems and forced vibration systems. In vibratory drilling with intrinsic vibration, the tool's characteristic frequency is used to cause it to vibrate naturally during cutting. Vibration can be maintained by a mass spring system within the tool holder itself. Alternatively, a piezoelectric system can be used to generate and control the vibration. These systems allow for high vibration frequencies (up to 2 kHz) and small dimensions (several micrometers), and are particularly suitable for drilling small holes.

[0034] Ultrasonic drilling utilizes oscillations within the ultrasonic range to create a hole. This is a non-rotational machining method for processing materials. It is particularly suitable for hard and brittle materials. The drilling tool is set to vibrate along the feed direction via ultrasound generated in an ultrasonic sensor, which also excites the vibration of particles in the supplied abrasive suspension. The workpiece is removed from a micro-region within a small fraction of the oscillation cycle. Ultrasonic drilling can also be used in conjunction with conventional drilling to improve operating parameters.

[0035] According to a preferred embodiment of the invention, a focused ion beam (FIB) is used to penetrate the plate stack in step (d). When high-energy ions bombard the sample, they sputter atoms off the surface. Due to its sputtering capability, the focused ion beam can be used as a tool for micrometer and nanometer processing, and can modify or process materials in the micrometer and nanometer range. For example, gallium ions are used as the focused ions, but other ions can also be used. Features in the 10 to 15 nm range can even be milled using a focused ion beam; feature milling in the micrometer range is entirely possible. One problem with the application of focused ion beams is that its focal depth is relatively shallow. Therefore, penetrating thick plates or thick plate stacks in one go can be difficult. However, even in this case, there are solutions, such as dividing the plate stack into several sub-stacks and then using the FIB to penetrate the sub-stacks separately, especially during lens switching, where precise alignment of the holes in different plates is critical. The sub-stacks can then be assembled into a whole stack.

[0036] In the aforementioned drilling method, the material removed through the perforation must be removed from the plate stack. According to a preferred embodiment of the invention, flushing holes can therefore be provided or have been provided in multiple plates of the plate stack, the diameter of which is larger than the holes in the first and second plates of the micro-optical unit. These flushing holes can be formed using the same method as the holes in the first and second plates of the micro-optical unit or by other methods; the method itself is not decisive here. Rather, it is important that the diameter of the flushing holes is chosen such that, during a flushing operation in the process chamber after penetrating the plate stack, the removed material can be removed or flushed away through these flushing holes. For example, liquids can be used as flushing agents, particularly in metal drilling processes. However, gases can also be used as flushing agents, for example, after perforation via laser drilling or after using a focused ion beam.

[0037] The flushing holes also allow for the removal or flushing away of any auxiliary materials that may be used in the fabrication of the board stack / micro-optical unit. For example, liquid can be introduced between multiple boards in a board stack before a mechanical drilling process, and then the liquid can be cooled to solidify before perforating the board stack. Thus, the forces acting during perforation can also be absorbed by the solidified liquid. After perforation, the board stack can be reheated to liquefy the solidified liquid / solid again, which can then be flushed out through the flushing holes.

[0038] According to a preferred embodiment of the present invention, the method further includes the following steps: after penetration according to step d), rinsing the plate stack and removing drilling material through rinsing holes in the first plate and the second plate of the micro-optical unit, wherein the following relationship applies to the diameter S of the rinsing hole relative to the diameter A of the hole in the first plate and the diameter A of the hole in the second plate of the micro-optical unit: S ≥ 10A, preferably S ≥ 100A.

[0039] According to another preferred embodiment of the present invention, the method further includes the following steps: Before proceeding with penetration according to step d). - Fill the space between the first plate and the second plate of the micro-optical unit with a rinsing agent; and - Cool the rinsing agent, and thus solidify it; and After penetration according to step d), - Heating the flushing agent to liquefy it; and - Remove the flushing agent from the middle space.

[0040] The aforementioned flushing hole can be used to fill and remove flushing solution.

[0041] According to another preferred embodiment of the present invention, the method further comprises the following step: after penetration according to step d). - Anneal the board stack.

[0042] The annealing of the plate stack is used to restore the soft magnetic properties or high permeability of the magnetic plates. Otherwise, voltage or oscillations that may occur in the method according to the invention for manufacturing micro-optical units for multi-particle beam systems could reduce the permeability to a level where it is no longer possible to achieve desired effects such as multiple deflections of individual particle beams. If the plate stack is annealed at high temperatures, care must also be taken to ensure that the electrical insulation between the individual plates in the stack can withstand the high temperatures of the annealing process. In principle, this can be ensured by selecting appropriate insulating materials.

[0043] According to another preferred embodiment of the invention, at least one of the plurality of plates in the plate stack comprises an insulating material as a substrate material, particularly ceramic, and the method further comprises the following steps, which are temporarily performed before method steps (a) to (d): (e) Forming a plurality of coarse holes in at least one plate having an insulating material as a substrate; and (f) Metallize these coarse holes; The subsequent implementation of method step (d) relates to penetrating the metallized coarse hole and thus forming a plurality of holes.

[0044] Therefore, in the exemplary embodiment, it is not the entire conductive plate of the plate stack, but a portion of the plate, specifically the metallized region around the coarse holes. This is sufficient to perform all material processing methods that require the conductivity of the perforated material. Essentially, the diameter of the coarse holes is larger than the aperture of the complete porous plate. In contrast, the diameter of the metallized coarse holes is smaller than the diameter of the complete aperture in the porous plate.

[0045] According to a preferred embodiment of the present invention, coarse pores are metallized by sputtering and / or by electroplating.

[0046] According to a preferred embodiment of the invention, a plurality of holes in the multiple plates of the plate stack are formed simultaneously in method step (d). For this purpose, a plurality of drilling components can be used simultaneously. These could be, for example, multiple laser pulses during laser drilling, or a plurality of electrodes (so-called "Manhattan electrodes") that are fixedly oriented relative to each other in a micro-discharge machining method. This type of simultaneous drilling generates holes very quickly.

[0047] According to an alternative embodiment of the invention, in method step (d), a plurality of holes are formed sequentially in a plurality of plates in a plate stack. This means that the entire plate stack is first fully penetrated at a first point, then fully penetrated at a second point, and so on. In this variant of the embodiment, the drilling method used is relatively simple in procedure.

[0048] According to a preferred embodiment of the invention, each of the plurality of holes has a diameter A, wherein the following relationship applies: 40 μm ≤ A ≤ 400 μm, preferably 80 μm ≤ A ≤ 400 μm or 110 μm ≤ A ≤ 400 μm. For a circular hole, the diameter naturally corresponds to twice the radius. In the case of holes of different shapes, such as elliptical holes, the minimum possible distance between the hole walls is defined as the diameter A. In the case of an ellipse, this is therefore equivalent to twice the minor axis. In the case of a stepped hole, which can be formed, for example, through a stepped electrode or through multiple drilling steps (e.g., first penetrating the plate using a small drilling member, and then partially drilling it open using a larger drilling member), the diameter A refers to the minimum diameter.

[0049] According to a preferred embodiment of the invention, the openings in the stacked plates are circular, elliptical, n-folded, or irregular in shape. In this way, the method according to the invention is very flexible.

[0050] According to a preferred embodiment of the present invention, the centers of adjacent holes in a plurality of plates in the plate stack are spaced apart by a distance B, wherein the following relationship applies under the following conditions: 70 μm ≦ B ≦ 400 μm, preferably 90 μm ≦ B ≦ 400 μm or 120 μm ≦ B ≦ 400 μm.

[0051] According to a preferred embodiment of the present invention, the following relationship applies to the thickness C of one of the plates in the plate stack: 20 μm ≦ C ≦ 500 μm, preferably 150 μm ≦ C ≦ 500 μm or 250 μm ≦ C ≦ 500 μm.

[0052] According to a preferred embodiment of the present invention, the following relationship applies to the spacing D between adjacent boards in a board stack: 1 μm ≦ D ≦ 100 μm, preferably 20 μm ≦ D ≦ 100 μm or 40 μm ≦ D ≦ 100 μm.

[0053] According to a preferred embodiment of the present invention, the following relationship applies to the total height H of the board stack: 50 μm ≦ H ≦ 1000 μm, preferably 300 μm ≦ H ≦ 1000 μm or 500 μm ≦ H ≦ 1000 μm.

[0054] Therefore, the method according to the invention can also penetrate relatively thick and relatively distant plates, especially through a fast and precise method. Particularly in the case of larger sizes, manufacturing processes using known planar integration technologies are much slower.

[0055] According to a preferred embodiment of the present invention, the micro-optical unit comprises at least a second plate stack or an additional plate stack. In this case, the second or additional plate stack of the micro-optical unit can be formed by method steps (a) to (d). However, the second or additional plate stack of the micro-optical unit may also be manufactured or has been manufactured by planarization processes and / or lithography methods. In principle, other manufacturing methods are also possible.

[0056] According to another preferred embodiment of the invention, the first plate stack and the second or other plate stack are aligned with each other in method step (g). High precision is required when aligning multiple plate stacks. However, such back-alignment of the plate stacks or the holes contained therein is naturally less precise than the inherent positioning of the holes within the plate stacks if the associated holes are precisely formed through the same method steps. Therefore, expediently, alignment of the plate stacks with each other is provided at those transitions between different plate stacks, which, from an electro-optical perspective, is more immune to misalignment. Reference is again made herein to statements relating to focused ion beam drilling. In principle, the sub-stacks described in the process correspond to several stacks. In particular, critical lens transitions should preferably belong to the same plate stack, which is preferably generated using the method according to the invention comprising steps (a) to (d).

[0057] According to another aspect of the present invention, the present invention relates to a micro-optical unit for a multi-particle beam system, the micro-optical unit being manufactured according to the methods described in the above-described variations of the embodiments.

[0058] According to another embodiment of the invention, the invention relates to a micro-optical unit for a multi-beam particle system, particularly for a multi-beam particle microscope. In this case, the micro-optical unit comprises a first porous plate made of metal and a second porous plate made of metal. The following relationship applies to the aperture A of the first and second porous plates: A ≥ 150 μm. Furthermore, in each case, the following relationship applies to the thickness C of the first and second porous plates: C ≥ 250 μm. The following relationship applies to the plate spacing D between the first and second porous plates: D ≥ 30 μm.

[0059] Therefore, the described micro-optical unit is a relatively large micro-optical unit, and it is made of metal. Fabricating such a micro-optical unit using known planar integration techniques is not always possible or would require a considerable amount of time.

[0060] According to another aspect of the present invention, the present invention relates to a multi-particle beam system, and more particularly to a multi-particle microscope having micro-optical units as described above.

[0061] According to a preferred embodiment of the invention, during operation of the multi-particle beam system, a voltage U can be applied to the first and / or second porous plates of the micro-optical unit, wherein U ≥ 250V, preferably U ≥ 300V or U ≥ 350V. It is generally not possible to apply such high voltages to porous plates using known micro-optical units manufactured using planar integration technology. Instead, voltages on the order of less than 200V can be used in these cases. Otherwise, flashover will occur between different porous plates. When using the aforementioned high voltages, which sometimes significantly exceed 250V, a relatively large plate spacing D is required. While this cannot generally be achieved by growing an insulating layer (such as silicon oxide), it can be achieved by other manufacturing methods, as the thickness of the insulating layer is generally limited by the method used in the growth process. It is particularly advantageous that the isolator can also be penetrated by some of the manufacturing methods or drilling methods described according to the invention (e.g., through laser drilling).

[0062] According to a preferred embodiment of the invention, the multi-particle beam system further includes a magnetic lens, which is positioned downstream of the micro-optical unit relative to the particle optical beam path of the multi-particle beam system during operation. In this case, the micro-optical unit has a final porous plate relative to the particle optical beam path of the multi-particle beam system. The final porous plate is magnetically permeable, wherein the following relationship applies to the relative permeability μr of the final porous plate material: μr ≥ 1000, preferably μr ≥ 10000 or μr ≥ 15000. In this case, during operation of the multi-particle beam system, the final porous plate of the micro-optical unit is positioned within the magnetic field formed by the magnetic lens. Therefore, during operation of the multi-particle beam system, individual particle beams passing through the micro-optical unit suddenly enter the magnetic field of the magnetic lens, which provides the option to set the azimuth tilt of the individual particle beams.

[0063] According to a preferred embodiment of the invention, the multi-particle beam system further includes a controller configured to control the magnetic lens and set its magnetic field strength. Furthermore, the controller is configured to set the azimuth tilt of individual particle beams by changing the magnetic field strength of the magnetic lens, wherein these individual particle beams pass through the magnetic lens during operation. Such setting options are particularly useful for examining samples with high aspect ratios: when examining samples with high aspect ratios, it is often particularly important to detect that the individual particle beams are incident on the sample surface in a telecentric manner to ideally scan structures with high aspect ratios. Another exemplary application option is a sample located within the magnetic field of the objective lens system (magnetic immersion lens). Due to the Lorentz force, charged particles undergo rotation or Lorentz rotation in the magnetic field. If the sample to be scanned is still within the magnetic field, the rotation of the charged particles in the magnetic field is incomplete, and the azimuth angular velocity component of the charged particles when incident on the sample is not zero. This results in the azimuth tilt of the individual particle beams. Such tilt is compensated by the described configuration of a final porous plate having high permeability within the magnetic field of a magnetic lens, such as a field lens.

[0064] There are also several applications where charged particle beams pass through, for example, slightly tilted objectives. This is possible, for instance, if the sample surface is tilted relative to the particle optical axis Z, i.e., the axis Z is not perfectly perpendicular to the sample surface.

[0065] Furthermore, certain aberrations of the objective lens can be corrected, for example, through the aforementioned configuration or through this passive multi-deflector.

[0066] According to another preferred embodiment, the final porous plate is made of Permenorm®. However, other materials are also possible. These include, in particular, soft magnetic standard nickel-iron alloys with approximately 50% nickel content. These alloys combine high saturation magnetic flux density with high maximum permeability.

[0067] Prior art encompasses a variety of magnetically permeable materials with a relative permeability μr ≥ 1000 suitable for the final porous plate. These include standard soft magnetic materials such as pure iron (e.g., Vacofer®); nickel-iron alloys with approximately 75% nickel content, such as molybdenum metal (Mu Metal), permeable alloys, or superpermeable alloys; nickel-iron alloys with approximately 50% nickel content, such as Permenorm®; cobalt-iron alloys with approximately 50% cobalt content, such as Vacolux®; or silicon-iron alloys with approximately 3% silicon content, such as Trafoperm®. These materials are also commercially available as thin films, for example, with thicknesses of 25 μm, 50 μm, 100 μm, or 250 μm. Due to their small thickness, plates made from these materials are, in principle, suitable for the final porous plate.

[0068] According to another aspect of the present invention, the present invention relates to a multi-particle beam system comprising the following: A single particle source is used to form a beam of charged particles; A multi-beam generator, through which the charged particle beam passes to form a plurality of first separately charged particle beams, the first separately charged particle beams forming a first field; A first particle optical unit having a first particle optical beam path and configured to image a formed first separate particle beam onto an object plane, such that the first separate particle beam strikes the object at the incident position where the second field is formed; An objective lens, particularly a magnetic objective lens, through which the first separate particle beam passes; and One controller; The multi-beam generator comprises a micro-optical unit having a plurality of consecutively arranged porous plates. In each case, a first charged particle beam sequentially passes through the porous plates. The micro-optical unit comprises a magnetically permeable final porous plate relative to the particle optical beam path, wherein the following relationship applies to the relative permeability μr of the final porous plate material: μr ≥ 1000, particularly μr ≥ 10000 or μr ≥ 15000. The first particle optical unit includes a magnetic field lens, wherein during the operation of the multi-particle beam system, the final porous plate of the micro-optical unit is positioned within the magnetic field formed by the magnetic field lens. The controller is configured to control the magnetic field lens and set its magnetic field strength. The controller is further configured to set the azimuth tilt of the first charged particle beam when it hits the object and / or passes through the objective lens by means of the change in the magnetic field strength of the magnetic field lens.

[0069] Therefore, the micro-optical unit of the multi-beam generator can be manufactured here according to the method described for manufacturing micro-optical units for multi-particle beam systems.

[0070] According to a preferred embodiment of the invention, the central hole of the final porous plate and the magnetic field lens are configured to be centered on each other. This centering is beneficial for setting the azimuth tilt or its accuracy.

[0071] According to another preferred embodiment of the invention, the z-component Bz of the magnetic field B on the particle optical axis Z has a value at the final perforated plate, and the following relationship applies to this value: 0.1 mT ≤ Bz ≤ 10.0 mT, preferably 1.0 mT ≤ Bz ≤ 10.0 mT. For example, given a magnetic field, the distance dFF between the final perforated plate and the lens center of the magnetic lens can be set such that the relationship of the magnetic field Bz is satisfied.

[0072] According to a preferred embodiment of the invention, in order to set the azimuth tilt of the first separate particle beam, the magnetic field strength B of the magnetic field lens is changed by a maximum of ±50% of its nominal value. Therefore, this change in magnetic field strength is a fine-tuning. A lookup table for different presets of magnetic field strength B (e.g., for different operating points of the multi-particle beam system) can be stored in the memory of the multi-particle beam system, and this allows for the targeted setting of the azimuth tilt value of the first separate particle beam. In this case, a nominal value is defined such that it conforms to the condition of fully correcting the azimuth beam tilt at the object, the sample surface, or the wafer surface.

[0073] According to a preferred embodiment of the invention, the final porous plate is made of Permenorm®. However, other materials are also possible, such as other soft magnetic standard nickel-iron alloys with a nickel content of approximately 50%.

[0074] According to another preferred embodiment of the invention, the multi-particle beam system is a multi-beam particle microscope. However, the multi-particle beam system may also be a different multi-particle beam system, such as a lithography system.

[0075] According to another preferred embodiment of the present invention, the multi-particle beam system further comprises the following: A detection system having a plurality of detection zones that form a third field; A second particle optical unit having a second particle optical beam path, configured to image a second individual charged particle beam emitted from an incident position in the second field onto a third field in the detection region of the detection system; and A beam splitter is disposed in a first particle optical beam path between the multi-beam particle source and the objective lens, and in a second particle optical beam path between the objective lens and the detection system; Both the first and second separate particle beams pass through the objective lens.

[0076] According to another preferred embodiment of the invention, a second micro-optical unit having a plurality of consecutively arranged porous plates is provided in the second particle optical beam path through which the second charged particle beam passes. In this case, the micro-optical unit has a magnetically permeable final porous plate relative to the particle optical beam path, wherein the following relationship again applies to the relative permeability μr of the final porous plate material: μr ≥ 1000, preferably μr ≥ 10000 or μr ≥ 15000. Furthermore, the second particle optical unit includes a magnetic projection lens. In this case, during operation of the multi-particle beam system, the final porous plate of the second micro-optical unit is disposed within the magnetic field formed by the magnetic projection lens. In this embodiment of the invention, the controller is configured to control the magnetic projection lens and set its magnetic field strength. In this case, the controller is further configured such that when the second charged particle beam impacts the detection area and / or when it passes through a contrast aperture arranged flush with the intersection of the second charged particle beam, its azimuth angle is tilted by the change in the magnetic field strength transmitted through the magnetic projection lens. Furthermore, in this case, the method for manufacturing micro-optical units for multi-particle beam systems according to the present invention is used to manufacture a second micro-optical unit having a final porous plate, as described previously in several embodiment variations. With the configuration of the described multi-particle beam system, multiple deflectors can be implemented in both the first and second particle optical beam paths of the multi-particle beam system. The described effects and advantageous embodiments can be achieved in a manner similar to those described in the first particle optical beam path.

[0077] Provided that no technical contradictions arise, the various embodiments and forms of the present invention can be combined with each other completely or partially. Simple Explanation of the Diagram

[0078] The invention will be better understood by referring to the accompanying drawings. In the drawings: Figure 1 schematically illustrates a multi-particle beam system; Figure 2 schematically illustrates the structure of the micro-optical unit; Figure 3 schematically illustrates the alignment problem in the case of a perforated plate; Figure 4 schematically illustrates the method steps of the manufacturing method for a micro-optical unit according to the present invention; Figure 5 shows a flowchart of the manufacturing method according to the present invention; Figure 6 schematically illustrates the method steps of the manufacturing method according to the present invention; Figure 7 schematically illustrates the method steps of the manufacturing method according to the present invention; Figure 8 schematically illustrates multiple configurations of the manufacturing method according to the present invention; Figure 9 schematically illustrates the method steps of the manufacturing method according to the present invention; Figure 10 schematically shows the Manhattan electrode and the porous plate formed therewith; Figure 11 schematically shows the porous plate of the micro-optical unit; Figure 12 schematically illustrates several variations of manufacturing methods for micro-optical units; Figure 13 shows another flowchart of the manufacturing method according to the present invention; Figure 14 schematically illustrates particle optical imaging through a symmetrical magnetic lens and through an asymmetrical magnetic lens; and Figure 15 schematically illustrates a configuration with a micro-optical unit and a magnetic lens for implementing a multi-deflector. Implementation

[0079] Figure 1 schematically illustrates a multi-beam particle microscope system 1. The multi-beam particle system 1 includes a beam-generating device 300 having a particle source 301 (e.g., an electron source). A diverging particle beam 309 is collimated by a series of focusing lenses 303.1 and 303.2 and incident on a porous configuration 305 forming micro-optical units. The porous configuration 305 includes several porous plates 306 and a field lens 308. A plurality of individual particle beams 3 or individual electron beams 3 are formed by the porous configuration 305. The midpoints of the multiple apertures in the porous plate configuration are positioned in a field that is imaged onto a separate field formed by the beam points 5 in the object plane 101. The spacing between the multiple midpoints of the apertures in the porous plates 306 can be, for example, 5 μm, 100 μm, and 200 μm. The diameter A of the holes is less than the distance between the midpoints of the holes; examples of the diameter are 0.2 times, 0.4 times, and 0.8 times the distance between the midpoints of the holes.

[0080] The porous configuration 305 and the field lens 308 are configured to form a plurality of focal points 323 of the primary beam 3 on the surface 321 using a grating configuration. The surface 321 does not need to be planar; it can also be a spherical curved surface to take into account the field curvature of the subsequent particle optics system.

[0081] The multi-beam particle microscope 1 further includes a system containing multiple electromagnetic lens systems 103 and an objective lens 102, which images the beam focal point 323 from the intermediate image surface 325 onto the object plane 101 in a reduced size. During this process, the first individual particle beam 3 passes through the beam splitter 400 and a beam deflection system 500, which deflects and scans the image field of multiple first individual particle beams 3 during operation. The first individual particle beams 3 incident on the object plane 101, for example, form a substantially regular field, wherein the spacing between adjacent incident positions 5 can be, for example, 1 μm, 10 μm, or 40 μm. For example, the field formed by the incident positions 5 can have rectangular or hexagonal symmetry.

[0082] The object 7 to be examined can be of any desired type, such as a semiconductor wafer or a biological sample, and may contain miniaturized components. The surface 15 of the object 7 is disposed in the object plane 101 of the objective lens 102. The objective lens 102 may include one or more electro-optical lenses. For example, this may be a magnetic objective and / or an electrostatic objective.

[0083] Primary particles 3 are incident on object 7, producing interaction products, such as secondary electrons, backscattered electrons, or primary particles that undergo motion reversal for other reasons. These interaction products are emitted from the surface of object 7 or from the first plane 101 or the object plane 101. The interaction products emitted from the surface 15 of object 7 are shaped by objective lens 102 to form secondary particle beam 9. In this process, secondary beam 9 passes through beam splitter 400 downstream of objective lens 102 and is guided to projection system 200. Projection system 200 includes imaging system 205 with projection lenses 208, 209, and 210, a contrast stop 214, and a multiparticle detector 207. The incident positions 25 of the second individual particle beam 9 on the detection area of ​​multiparticle detector 207 are located in a third field at regular intervals. Exemplary values ​​are 10 μm, 100 μm, and 200 μm.

[0084] The multi-beam particle microscope 1 further includes a computer system or a control unit 10, which may have a single-component or multi-component design and is designed to control the individual particle optical components of the multi-beam particle microscope 1 and evaluate and analyze the signals obtained by the multi-particle detector 207 or the detection unit.

[0085] Further information regarding such multi-beam particle systems or multi-beam particle microscopes 1 and the components used therein, such as particle sources, perforated plates, and lenses, is available from PCT patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596 A1, WO 2011 / 124352 A1 and WO 2007 / 060017 A2 and German patent applications DE 10 2013 016 113 A1 and DE 10 2013 014 976 A1, the disclosures of which are incorporated herein by reference in their entirety.

[0086] The porous configuration 305 forms a micro-optical unit 305. In the example shown, through this micro-optical unit, during the operation of the multi-particle beam system 1, a plurality of first individual particle beams 3 are initially formed at the first porous plate (so-called filter plate) and are also actively formed at other porous plates. Here, the micro-optical unit 305 itself can be configured in different ways.

[0087] Figure 2 illustrates an example of a micro-optical unit 305 designed as a multi-beam generator 305. In the illustrated example, the multi-beam generator 305 comprises a series of six porous plates 304, 306.1, 306.2, 306.3, 306.4, and 310 along the z-direction and a global focusing lens 307, the orientation of which corresponds to the propagation direction of the individual particle beams 3. Each of the porous plates 304, 306.1 to 306.4 and 310 contains a plurality of holes 351 through which a plurality of individual particle beams 3 pass. The cross-sections through the holes 351 in Figure 2 are not drawn to scale.

[0088] A plurality of porous plates 304, 306.1, 306.2, 306.3, 306.4, and 310 are spaced apart from each other by spacers 83.1 to 83.5. Furthermore, a spacer 86 is disposed between the final porous plate 310 and the global lens electrode 307. Due to the incident of collimated particles or electron beams 309, a plurality of first individual particle beams 3 are formed during passage through the first porous plate 304, also referred to as a filter plate or pre-perforated plate. The pre-perforated plate 304 includes a metal layer 99 on its beam input side for blocking and absorbing electrons incident on the electron beams 309 surrounding the plurality of holes 85. In this case, the material of the pre-perforated plate 304 is generated from a conductive material as shown in the example, such as from doped silicon, and is at ground potential.

[0089] In the example shown in Figure 2, the next multi-aperture plate is a multi-stigmator plate 306.1. The multi-stigmator plate 306.1 contains a plurality of four or more electrodes 82, for example, each of these apertures has eight electrodes. During operation of the multi-beam particle microscope 1, different voltages, for example, voltages ranging from -20 V to +20 V, can be applied to each of these electrodes, individually affecting each individual particle beam 3. For example, an antisymmetric voltage difference can be used to deflect each individual particle beam 3 by several μm in each direction to pre-correct the distortion of the illumination unit 100. Astigmatism pre-correction can also be performed on each individual particle beam 3. Through the offset voltage, each multi-pole element can be attached to act as an ensemble lens.

[0090] In principle, the porous plates 306.2, 306.3, and 306.4 can be any desired trajectory correction plate with a monolithic design and, in the illustrated example, the corresponding voltages V1, V2, and V3 applied. The porous plates 306.2, 306.3, and 306.4 can also form a single-lens array. Different holes 351 in the same porous plates 306.2, 306.3, and 306.4 can have the same or different designs, for example, different diameters, to account for the dependence of the correction field in the trajectory correction of individual particle beams 3.

[0091] The porous plate 310 is a double-layer porous plate and includes a plurality of annular electrodes 79 for a plurality of pore sizes, wherein each annular electrode is configured to individually change or correct the focal position of the first separate particle beam 3 passing through it. In this case, the upper layer is insulated from the layer having the annular electrodes 79 and is made of, for example, a conductive material such as doped silicon.

[0092] Field lens 307 includes a ring electrode 84, which can be subjected to a high voltage, for example, from 3kV to 20kV, or from 12kV to 17kV. In the example shown, global focusing lens 307 provides a global electrostatic lens field for global focusing of the plurality of individual particle beams 3.

[0093] The micro-optical unit 305 or its porous plate shown in Figure 2 is, in principle, manufactured using known manufacturing methods or planar integration technology. However, at least some porous plates, such as porous plates 306.2, 306.3, and 306.4, can also be manufactured using the manufacturing method according to the present invention. Due to the excellent performance of such porous plates 306.2, 306.3, and 306.4 manufactured according to the present invention (relatively high voltages V, V2, V3 and applicability to relatively large plate spacing or thick spacers / isolation elements 83.2, 83.3, 83.4, 83.5), it is possible, for example, to make the porous plate 310 with the annular electrode 81 redundant.

[0094] Figure 3 schematically illustrates the alignment problem in the case of porous plates 350, which are each manufactured independently of each other, i.e., independent in each case. Figure 3(a) schematically shows the arrangement of three plates 360 without openings. Figure 3(b) schematically shows the use of a drilling member 900, which can be of any type in principle. For this, Figure 3 only considers the principle. The effective direction of the drilling member 900 is schematically indicated by arrows in Figure 3(b). The drilling member 900 forms an opening 351 in the plate 360, thereby exposing the porous plate 350 from the plate 360. It should be understood that, for clarity, only one opening 351 is depicted in Figure 3(c), but the porous plate 350 essentially contains several openings 351. Figure 3(d) now shows three porous plates 350.1, 350.2, and 350.3 assembled to form a porous configuration 305 or a micro-optical unit 305. For this purpose, conductive porous plates 350.1, 350.2, and 350.3 are aligned with each other and are also fixed and insulated. In the example shown, this is achieved through spacers 370.1 and 370.2. In this case, openings 351.1 and 351.2 and 351.3 are not precisely positioned on top of each other, i.e., not centered on top of each other. Therefore, these openings are not flush aligned. Precisely aligning or orienting the openings 351.1, 351.2, and 351.3 in porous plates 350.1, 350.2, and 350.3 relative to each other is very difficult, if not impossible. This is especially true if porous plates 350.1, 350.2, and 350.3 are made of metal: this is because in this case, they do not transmit visible light or infrared radiation, and optical alignment, typically used in die bonding machines, is very difficult. Therefore, it is not easy to replace the semiconductor-based plates in the porous configuration 305 with metal plates.

[0095] However, the manufacturing method according to the present invention provides a solution in which a plate made of metal can first be used to manufacture the micro-optical unit 305, and secondly, it can be fully and precisely aligned. Figure 4 schematically illustrates the method steps of the manufacturing method for the micro-optical unit 305 according to the present invention:

[0096] Figure 4(a) first shows three plates 360.1, 360.2 and 360.3 for the micro-optical unit 305, which are conductive and made of metal in the example shown.

[0097] Figure 4(b) shows the arrangement of plates 360.1, 360.2, and 360.3 relative to each other. In this configuration, plates 360.1, 360.2, and 360.3 are fixed relative to each other and electrically insulated from each other by spacers 370.1 and 370.2. Spacers 370.1 and 370.2 may be made of silicon oxide, for example.

[0098] Figure 4(c) schematically illustrates the penetration of a stack of boards with plates 360.1, 360.2, and 360.3 through the drilling member 900. This is only schematically depicted in Figure 4(c); the drilling direction is indicated by arrows. It is important that the entire stack of boards is penetrated in principle by the same drilling member 900 in a single attempt and during the same drilling process.

[0099] Figure 4(d) shows the result of the drilling process: in the example shown, holes 351.1, 351.2, and 351.3 are perfectly aligned with each other, and the centers of holes 351.1, 351.2, and 351.3 are located at the center of axis Z. Again, Figure 4 merely illustrates a series of holes 351.1, 351.2, and 351.3; however, in essence, there are several holes or multiple sequences of holes in the perforated plates 350.1, 350.2, and 350.3.

[0100] Furthermore, it is conceivable that, in addition to boards 360.1, 360.2, and 360.3, insulating boards or multiple insulating layers can also be penetrated through the drilling member 900. Whether this is possible depends solely on the drilling method used.

[0101] Figure 5 schematically illustrates a flowchart of a method for manufacturing a micro-optical unit 305 for a multi-particle beam system 1 according to the present invention: in step S1, a conductive first plate 360.1 for the micro-optical unit 305 is first provided.

[0102] In method step S2, a conductive second plate 360.2 is provided for the micro-optical unit 305.

[0103] In method step S3, a plate stack is established: the establishment of a plate stack includes the step of stacking the first plate 360.1 and the second plate 360.2 of the micro-optical unit 305 on top of each other, wherein the first plate 360.1 and the second plate 360.2 of the micro-optical unit 305 are fixed relative to each other in the plate stack and are electrically insulated from each other. For example, this can be achieved by using insulating spacers 370.1, 370.2.

[0104] Then, method step S4 performs the following operation: perforating the entire stack of plates formed with at least the first plate 360.1 and the second plate 360.2 having micro-optical units 305, thereby forming a first plurality of holes 351.1 in the first plate 360.1 of the micro-optical units 305 and a second plurality of holes 351.2 in the second plate 360.2 of the micro-optical units 305. Thus, a sequence of holes 351.1, 351.2 in the plates 360.1, 360.2 of the stack of plates formed during the same drilling process has precise alignment, particularly in a process-inherent manner. Alternatively, the stack of plates may further include at least one additional plate and thus include at least a conductive third plate 360.3 of the micro-optical units 305. In this case, the third plate 360.3 of the micro-optical units 305 is fixed relative to and electrically insulated from the first plate 360.1 and the second plate 360.2 of the micro-optical units 305. During the implementation of method step S4, the third plate of the micro-optical unit 305 is also penetrated, thus forming a third plurality of holes 351.3 in the third plate 360.3 of the micro-optical unit 305. One or more of the aforementioned plates in the micro-optical unit 305 may be made of metal. According to a preferred embodiment of the invention, all perforated plates are made of metal. However, in addition to conductive plates, other plates that are non-conductive but made of insulating materials such as silicon dioxide may also be provided.

[0105] In method step S4, the board stack can be penetrated in different ways: examples of drilling methods include, for example, laser drilling, micro-discharge machining drilling, mechanical high-speed micro-drilling, vibratory drilling, ultrasonic drilling, or using focused ion beam (FIB). For details regarding these methods, refer to the explanations given in the general section of this specification.

[0106] Alternatively, in step S5, the plates can be flushed, and the drilling material can be removed through flushing holes in the first plate 360.1 and the second plate 306.2 of the micro-optical unit 305. In this case, the following relationship applies to the diameter S of the flushing hole relative to the diameter A of the hole in the first plate 306.1 and the second plate 306.2 of the micro-optical unit 305: S ≥ 10A, preferably S ≥ 100A.

[0107] An improved manufacturing method for the micro-optical unit 305 used in the multi-particle beam system 1 is shown in the flowchart of FIG13. In this case, the method steps S1 to S3 are first implemented as described above. Before perforating the plate stack according to step S4, in the exemplary embodiment described, the intermediate space between the first plate 306.1 and the second plate 306.2 of the micro-optical unit 305 is filled with a liquid rinsing agent and cooled in step S11, so that the rinsing agent is solidified in step S12. For example, temperature control is achieved by a method performed in a process chamber, the internal temperature of which can be set, or the liquid is supplied in a heated state and then self-cooled. Then, the entire plate stack is perforated in step S4. By configuring / supplying the solidified rinsing agent, the forces acting on plates 306.1 and 306.2 during the penetration process can be better absorbed, distributed, and dissipated. This can help to better prevent plates 306.1 and 306.2 from bending. In another method step S13, the rinsing agent is heated and thus liquefied. For example, the entire board stack can be heated during the process, thus heating the rinsing agent as well. In a separate method step S14, the rinsing agent, now again in liquid form, is removed from the intermediate space. The aforementioned rinsing holes can be used to fill and remove the rinsing agent.

[0108] Alternatively, the entire plate stack can be annealed in an additional method step. This may be necessary in the case of the final porous plate 350.f with magnetic permeability to ensure its permeability, for example, for use in a multi-particle beam system 1 to combine the micro-optical unit 305 with the magnetic lens 308 as a magnetic multi-deflector.

[0109] Figure 6 schematically illustrates the method steps of the manufacturing method according to the present invention. In the exemplary embodiment shown in Figure 6, the plate 360 ​​of the micro-optical unit 305 is non-conductive or completely non-conductive. The conductivity of the plate is provided only in a portion, specifically in the area around where the hole 351 has not yet been formed:

[0110] Specifically, three non-conductive plates 360 are initially provided for the micro-optical unit 305. The plates 360 may have an insulating material as a substrate, such as ceramic. Coarse holes 361 can now be formed in these plates 360. The coarse holes 361 are larger than the holes 362 ultimately formed in the micro-optical unit 305.

[0111] The coarse aperture 362 is metallized in a separate process step (see Figure 6(c)). For example, the metallization of the coarse aperture 361 can be carried out by sputtering or electroplating. In this process, conductive regions 363 are formed around or adjacent to the coarse aperture 362. These, in turn, have openings 363. The diameter of these openings is smaller than the diameter of the final aperture 351 of the micro-optical unit 305.

[0112] In another step of the process, plates 360.1, 360.2, and 360.3, having metallized coarse holes 361, are configured to be fixed relative to each other and electrically insulated from each other. In this case, spacers 370.1 and 370.2 may be electrically insulated; however, this is not necessarily the case, as the plate material of plates 360.1, 360.2, and 360.3, being ceramic, is already sufficiently insulating. Openings 363.1, 363.2, and 363.3 are not perfectly aligned with each other. However, at this stage of the manufacturing process, this is not necessary.

[0113] This is because, as shown in Figure 6(e), the metallized coarse hole 361 or conductive regions 362.1, 362.2, and 362.3 are subsequently penetrated. Again, Figure 6(e) schematically shows the drilling member 900 and its direction of movement in this respect.

[0114] Therefore, as shown in Figure 6(f), holes 351.1, 351.2 and 351.3 are formed that are perfectly aligned with each other or precisely aligned with each other in a way that is inherent to the process.

[0115] Therefore, the manufacturing method described in Figure 6 not only allows for the manufacture of monolithic porous plates 350.1, 350.2, and 350.3 that are themselves (fully) conductive; conversely, annular electrodes can also be achieved through the manufacturing method according to the invention. In this case, the annular electrodes are formed by the conductive regions 362.1, 362.2, and 362.3 in the illustrated example. The wiring supply for the individual annular electrodes must be implemented in further method steps; this is more complex than in the case of the monolithic porous plate 350, but it is also achievable. This can be achieved, for example, by performing a metal printing process prior to the plate stack assembly. Conductor tracks can also be applied, for example, by a combination of sputtering and electroplating.

[0116] Figure 7 schematically illustrates the steps of a method for manufacturing a micro-optical unit 305 according to the present invention. For example, a stack of plates having plates 360.1, 360.2, and 360.3 as shown in Figure 7(a) can be manufactured as described in conjunction with Figures 4(a) and 4(b). However, unlike the case shown in Figure 4(c), the perforations in the stack of plates in Figure 7(a) are now different, particularly in terms of the drilling direction: this is because the stack of plates is penetrated at an angle. The resulting angled holes 351.1, 351.2, and 351.3 are also precisely aligned with each other, as shown by the dashed guide line in Figure 7(b). However, in this case of angled penetration, the holes 351.1, 351.2, and 351.3 are not perfectly circular but slightly elliptical. The ellipticity depends on the degree of inclination relative to the normal of the stack of plates during perforation.

[0117] Figure 8 schematically illustrates several variations of the manufacturing method according to the present invention, wherein a focused ion beam (FIB) is used to penetrate a plate stack. The plate stack shown comprises a total of six films 360.1, 360.2, 360.3, 360.4, 360.5, and 360.6 sandwiched within a frame. This is shown by the frame region 380 and the film region 381.

[0118] The plate stack shown should function as a single lens, for example, after penetrating the entire plate stack. Therefore, voltages U1, U2, and U3 are schematically indicated in Figure 8. However, instead of a single plate 360 ​​with a total height H over the entire plate width, two films with a small thickness h are provided. In this case, the corresponding voltages are applied to the lower and upper films, respectively. From an electro-optical perspective, the cavities 382.1, 382.2, and 382.3 actually do not produce significant differences in their arrangement between films 360.1 and 360.2, between films 360.3 and 360.4, and between films 360.5 and 360.6. Insulating spacers 370.1 and 370.2 are again arranged in a known manner between the correspondingly associated film pairs.

[0119] In cases where penetration of a plate stack is required, a focused ion beam can now be used in the same drilling process, starting from the top, first penetrating the topmost film 360.1, then the next film 360.2, and so on, in principle again precisely, using the same method steps or in a manner that does not require changing the position of the FIB pillars, at least not in the x- or y-direction, i.e., the x and y positions of the FIB pillars, and thus fixing the x and y positions of the hole 351 to be formed. The fact that only a portion of the thin film with a height of h needs to be penetrated can be taken into account that the focused ion beam has only a relatively small focal depth and therefore can only penetrate relatively thin layers. Therefore, as shown in Figure 8, penetration of the entire plate stack is particularly suitable for plate stacks with a small total height (e.g., up to several micrometers).

[0120] The procedure shown in Figure 9 represents a solution to a situation where the overall height of the plate stack is relatively large and the depth of focus of the focused ion beam is limited: the entire stack system with plates 360.1 to 360.6 is divided into four sub-stacks. In particular, plates 360.2 and 360.3, and plates 360.4 and 360.5, respectively form independent stacks as defined in Request 1. Now, the individual stacks or sub-stacks are individually penetrated through the FIB or through the focused ion beam in each case. In this case, the stacking according to Figure 9(b) results in a lens transformation. Here, the alignment of the apertures formed in plates 360.2 and 360.3 is particularly important. This also applies to the lens transformation between plates 360.4 and 360.5, as shown in Figure 9(c). In contrast, transformations within the same lens are less important. Therefore, the sub-stacks can be assembled after individual penetration of the sub-stacks (Figure 9(b) and (c)) and the individual plates or films (Figure 9(a) and (d)). The performance of the micro-optical unit 305 is not significantly compromised, and the corresponding alignment is performed. This assembly of the sub-stacks is shown in brackets in Figure 9. This again produces the micro-optical unit 305.

[0121] In principle, a plurality of holes in multiple plates in a stack of plates can be formed sequentially. However, at least some of the plurality of holes in multiple plates can also be formed simultaneously. An example of this is shown in Figure 10: Figure 10a shows a Manhattan electrode as a drilling member 900. The Manhattan electrode comprises a plurality of electrodes 902 disposed on a substrate element 901. In principle, the Manhattan electrode is therefore a multi-electrode. The Manhattan electrode can be used to simultaneously form multiple openings at different locations in the plate 360, which can be described as batch formation. The result of the perforation process is shown in Figure 10b: a porous plate 350 with a plurality of circular holes 351 is shown, the arrangement of which corresponds to the arrangement of the electrodes 902.

[0122] The Manhattan electrode shown in Figure 10 can be used, for example, in micro-discharge machining methods. However, the principle can also be applied to other drilling methods.

[0123] Figure 11 schematically illustrates a plurality of porous plates 350 of a micro-optical unit 305. In this document, Figure 11(a) shows a plurality of circular holes 351, each having the same diameter and arranged in a regular pattern. Figure 11(b) shows a porous plate 350 with circular holes 351; however, the diameter of the holes varies within the porous plate or depends on the position of the holes within the respective plates 350. In the example shown, the diameter of the holes 351 exhibits radial dependence with respect to a distance C from the center in the porous plate 350.

[0124] Figure 11(c) shows a porous plate 350 with elliptical holes 351. Its longitudinal axis l varies according to the center M, specifically based on the orientation and size of the center M.

[0125] All the perforated plates 350 shown in Figure 11 are monolithic perforated plates, to which only a single voltage is applied in each case. Due to the conductivity of the plate 350, the holes 351 produce an effect or lens effect, the size of which still depends only on the size and shape of the holes.

[0126] In principle, the shape of the holes 351 in the plates 360 and 350 of the plate stack can be circular, elliptical, n-folded, or irregular. These holes are preferably configured through a grid, such as a hexagonal grid. However, they can also be configured as, for example, square or rectangular grids.

[0127] According to an exemplary embodiment, adjacent holes 351 in a plurality of stacked plates have a distance B, and the following relationship applies to this distance: 70 μm ≦ B ≦ 400 μm, preferably 90 μm ≦ B ≦ 400 μm or 120 μm ≦ B ≦ 400 μm.

[0128] For example, the following relationship can be applied to the thickness C of plates 360 and 350 in a plate stack: 20 μm≦C≦500 μm, preferably 150 μm≦C≦500 μm or 250 μm≦C≦500 μm.

[0129] According to an exemplary embodiment, the following relationship can be applied to the plate spacing D between adjacent plates 350 and 360 in a plate stack: 1 μm ≦D ≦100 μm, preferably 20 μm ≦D ≦100 μm or 40 μm ≦D ≦100 μm.

[0130] According to an embodiment of the present invention, the following relationship applies to the total height H of the plate stack: 50 μm ≤ H ≤ 1000 μm, preferably 300 μm ≤ H ≤ 1000 μm or 500 μm ≤ H ≤ 1000 μm. Here, the total height H of the plate stack is considered to be the height of the plate stack simultaneously penetrated by the drilling member 900. Essentially, the micro-optical unit 305 may have at least a second or at least one additional plate stack. The second or additional plate stack of the micro-optical unit may also be formed by the method described in the present invention. However, the second or additional plate stack of the micro-optical unit 305 may also be formed by other methods, such as by planarization and / or lithography. The second or additional plate stack can then be aligned relative to the first plate stack.

[0131] When the size of the micro-optical unit 305 is relatively large, a relatively large micro-optical unit 305 can be provided. For example, when the aperture A is A≧150 μm, the thickness C of the porous plate 350 is C≧250 μm, and the plate spacing D between the porous plates 350 is D≧30 μm. During the operation of the multi-particle beam system, a relatively large voltage U can be applied to this relatively large micro-optical unit 305, for example, U≧250V, preferably U≧300V and U≧350V. This is particularly advantageous in multi-particle beam systems using a large number of individual particle beams 3, where the field dependence of imaging aberrations, such as field curvature or field astigmatism, is particularly large, especially in the edge regions of a large-grid multi-particle beam configuration.

[0132] Figure 12 schematically illustrates several alternative manufacturing methods for the micro-optical unit 305. In contrast to the aforementioned methods, it is possible that different plates are configured on top of each other or different layers are stacked on top of each other without penetrating each other; instead, a negative mold 910 is provided around which the various layers are initially constructed. The negative mold 910 is removed at the end of the process, thus the holes 911 defined by the negative mold 910 are precisely aligned with each other in a process-inherent manner. Therefore, complex alignment problems are also avoided according to this example.

[0133] Specifically, a negative mold can therefore be provided in the first method step. For example, this can have a Manhattan-like structure that defines the later position of the hole 911. Furthermore, individual electrodes (such as, for example, ring electrodes or lines for providing voltage to the electrodes) can also be provided by this negative mold. This central negative mold, which at least defines the size of the subsequent hole 911, can be configured in various ways. For example, the negative mold can be photoresist, silicon dioxide, etched metal (laser radar processes), coated metal (for deposition purposes), etc. In Figure 12a, the negative mold 910 is schematically depicted as a central block. The central block is disposed on the substrate 390. For example, this can be a wafer made of, for example, silicon.

[0134] After providing the basic structure including the negative mold 910, various layers can be deposited on the substrate 390. For example, in the example shown, the first metal layer 392 can be deposited on the substrate 390, for example, by sputtering or by a combination of sputtering and electroplating.

[0135] Subsequently, an additional layer 393 is deposited on the conductive layer 392. In principle, this is an insulating layer. The conductive layer may be insulating from the outset (e.g., via sputtering deposition of an insulator such as silicon dioxide), or the layer may have been initially a galvanic deposition that then lost its original conductivity and became an insulator through heat treatment. In principle, the electrolytic process for isolators is known from the prior art in a separate context.

[0136] The described alternating deposition process of conductive and non-conductive layers can be repeated. In the example shown, a metal layer 394 is then deposited, followed by another insulating layer 395; then another metal layer 396, and so on. The negative mold 910 is then removed at the end of the process: this is schematically depicted in Figure 12b. The plurality of holes 911 formed in this process are precisely aligned with each other.

[0137] The advantage of the technique of applying isolators via galvanocouplers and making them insulators only during heat treatment or baking is that, in principle, all the aforementioned layers (e.g., 392 to 396) can be applied via galvanocouplers. This is easier to control in the process and can be managed without any possible machine changes when applying different layers. The contamination handling issues of the galvanocoupler process are also fewer than those of the sputtering process.

[0138] Figure 14 schematically illustrates particle optical imaging through a symmetrical magnetic lens and an asymmetrical magnetic lens. The formation of beam tilt is illustrated schematically. Imaging with a symmetrical magnetic lens 700 is shown in Figure 14(a). In principle, the magnetic lens 700 can be an objective lens, field lens, projection lens, or any other magnetic lens. Only the principle is explained here. The Z component Bz of the magnetic field induced by the lens 700 is plotted along the Y-axis. The object to be imaged, indicated by the upright arrow, is located upstream of the magnetic lens 700 relative to the particle optical axis Z. It is important here that the object to be imaged, G, is located outside the magnetic field of the magnetic lens 700. The particle optical image B appears downstream of the magnetic lens 700. Figure 14(a) illustrates, for example, the particle beam path of a parallel or field beam, which is imaged through the focal point F in the focal plane E. Furthermore, the central beam is also plotted. Therefore, Figure 14(a) shows a very general imaging situation through the magnetic lens 700.

[0139] The azimuth angular velocity components (vazimuthal) of particle beams 3 and 9 moving parallel to the particle optical axis Z are now plotted below the schematic depiction of the beam path through the magnetic lens 700. Before the charged particle beams 3 and 9 enter the magnetic lens 700 or its magnetic field B or Bz, the azimuth angular velocity component (vazimuthal) is zero. As the charged particles or particle beams 3 and 9 enter the magnetic field B or Bz of the magnetic lens 700, they begin to rotate, and the azimuth angular velocity component (vazimuthal) increases, reaching its maximum value at the center of the magnetic lens 700. The azimuth angular velocity component (vazimuthal) then decreases, and the charged particles or charged particle beams 3 and 9 leave the magnetic lens 700 without any azimuth angular velocity component, i.e., (vazimuthal) = 0.

[0140] For comparative purposes, Figure 14(b) shows the particle optical beam path when the magnetic lens 700 is a magnetic immersion lens. Here, the object G to be imaged is therefore located within the magnetic field B or Bz of the magnetic lens 700. The decisive factor is that the magnetic field B or Bz experienced and passed through by the charged particle or electron is not symmetric, but asymmetric: the off-axis electron is emitted from the object G parallel to the particle optical axis, initially without an azimuth angular velocity component. It then rotates within the magnetic lens 700 and leaves the magnetic field with an azimuth angular velocity component due to the asymmetry. Therefore, vazimuthal ≠ 0 applies. This azimuth angular velocity component causes the electron beam, or generally the charged particle beam, to tilt. Thus, for example, the parallel beams no longer meet concentrically in the focal plane E. Therefore, the situation depicted in Figure 14(b) is typical for, for example, a multi-beam particle microscope 1 where the objective lens 102 is a magnetic immersion lens. Therefore, beam tilt occurs when incident on the sample 7.

[0141] The basic concept of the local state pattern of the present invention is the aforementioned beam tilt, which, from the perspective of the charged particle beam, can be caused not only by an asymmetric magnetic field but also compensated for: if charged particles or particle beams 3 and 9 suddenly enter the magnetic field, this in principle corresponds to an asymmetric channel through the magnetic field of the magnetic lens 700. Therefore, appropriate techniques can make it possible to compensate for unwanted beam tilt in the particle optical beam path or to set the beam tilt in the particle optical beam path in a targeted manner.

[0142] Figure 15 schematically illustrates a configuration having a micro-optical unit 305 and a magnetic lens for implementing multiple deflectors. For example, the configuration shown in Figure 15 can be integrated into the multi-beam particle microscope 1 shown in Figure 1; in this case, the magnetic lens corresponds to magnetic lens 308. This is assumed as in the following example.

[0143] The micro-optical unit 305 comprises a plurality of consecutively arranged porous plates 350.1, 350.2, and 350.3, in each case through which a first charged particle beam 3 passes consecutively. For example, the micro-optical unit 305 can be manufactured by a method according to the invention for manufacturing a micro-optical unit 305 for a multi-particle beam system 1. Relative to the first particle optical beam path, the micro-optical unit 305 has a final porous plate 350.f, which corresponds to porous plate 350.3 in the illustrated example. This final porous plate 350.f is magnetically permeable. The relative permeability μr of the final porous plate material satisfies the relationship μr ≥ 1000, particularly μr ≥ 10000 or μr ≥ 15000. The material of the final porous plate 350.f can be, for example, Permenorm®, or other materials. With respect to its central aperture 351.c, the final porous plate 350.f is centrally positioned relative to the magnetic field lens 308.

[0144] To provide options for setting or correcting the orientation tilt of the first charged particle beams 3a, 3b, and 3c, the final porous plate 350.f of the micro-optical unit 305 is now positioned within the magnetic field 701 formed by the magnetic field lens 308 during operation of the multi-particle beam system 1. The magnetic field 701 of the magnetic field lens 308, or the region where the magnetic field 701 of the magnetic lens 308 exists, is schematically shown in a simplified manner through the dashed lines in Figure 15.

[0145] Considering the permeability of the final porous plate 350.f, the magnetic field 701 of the magnetic lens 308 in Figure 15 experiences a sharp boundary in practice, allowing the first individual charged particle beams 3a, 3b, and 3c to suddenly enter the magnetic field 701. In this case, the azimuth tilt of the first individual charged particle beams 3a, 3b, and 3c is substantially proportional to the magnetic field strength and depends on the field height or the distance of the observed individual charged particle beams 3 from the particle optical axis Z. Thus, in the example shown, charged particle beam 3a experiences an upward tilt, and charged particle beam 3c experiences a downward tilt, while beam 3b on the particle optical axis Z shows no tilt.

[0146] The asymmetry of the magnetic field 701 is also schematically shown through a diagram of the geometric principal axis Ax of the field lens 308 and two distances dFF and d1: the distance dFF between the end of the final porous plate 350.f and the center C of the magnetic field lens 308 along the particle optical axis Z is less than the distance d1 from the center C of the magnetic field lens 308 to the end of the effective range of the magnetic field. In the example shown, dFF = d1 therefore applies. In the example shown, dFF is chosen such that, during the operation of the multi-particle microscope 1, for example, the following relationship applies to the magnetic field 701 at the final porous plate 350.f or the magnetic field Bz on the Z-axis: 0.1 mT ≦ Bz ≦ 10.0 mT, and in particular 1.0 mT ≦ Bz ≦ 10.0 mT.

[0147] The controller 10 or a portion of the controller 10.1 of the multi-particle beam system 1 is configured to control the magnetic field lens 308 and set its magnetic field strength. Furthermore, the controller 10 or a portion of the controller 10.1 is also configured to use the change in the magnetic field strength of the magnetic field lens 308 to set the azimuth tilt when the first separately charged particle beams 3a, 3b, 3c (or the first separately charged particle beam 3) are incident on the object 7 and / or pass through the objective lens 102 of the multi-particle beam system 1.

[0148] Furthermore, in the example shown, in order to set the azimuth tilt of the first magnetic field lens 308, the magnetic field strength of the magnetic field lens 308 is changed by a maximum of ±50% of its nominal value. In this case, for example, the nominal value is defined as the value that makes its azimuth tilt fully corrected at the object 7 or at the surface of an object such as a wafer surface.

[0149] Figure 15 illustrates a specific example of a magnetic multi-deflector. This example describes the specific configuration of the magnetic multi-deflector in the particle optical beam path, namely, in or directly downstream of the primary beam path of the multi-beam generator 305 or micro-optical unit 305 in the illustrated example, thereby completely forming a plurality of first separately charged particle beams 3 in a multi-particle beam system. However, in principle, a configuration with micro-optical unit 305 and magnetic lenses 700 at other locations in the particle optical beam path can be provided, more specifically, in both the primary and secondary beam paths. Therefore, the magnetic lens need not be a field lens 308; rather, it can be any desired magnetic lens 700.

[0150] Furthermore, in principle, charged particle beams will not suddenly enter the magnetic field 701 of the magnetic lens 700, but will only suddenly leave the magnetic field of the magnetic lens 700. The fundamental condition for setting the azimuth angle tilt of individual charged particle beams lies solely in the asymmetry of the magnetic field through which the individual charged particle beams pass. Therefore, instead of placing the final porous plate of the micro-optical unit within the magnetic field of the magnetic lens, the initial (i.e., first) porous plate of the micro-optical unit can be placed within the magnetic field of the upstream magnetic lens.

[0151] The foregoing exemplary embodiments should not be construed as limiting the present invention, but are merely for a better understanding of the invention. The exemplary embodiments may be combined, in whole or in part, without causing any technical inconsistencies.

[0152] 1: Multi-beam particle system / multi-beam particle microscope 3: Particle beam / Electron beam / Primary beam / First-order particle beam / Primary particle 3a, 3b, 3c: The first one is a non-charged particle beam. 5: Ladder point / incident position 7:Object 9: Secondary beam / Second separate particle beam / Particle beam 10: Controller 10.1: Controller 15: Surface 25: Location of incidence 81: Ring electrode 82: Electrode 83.1: Spacer 83.2: Spacer / Isolator 83.3: Spacers / Isolators 83.4: Spacers / Isolators 83.5: Spacers / Isolators 84: Ring electrode 85: Kong 86: Spacer 99: Metal layer 100: Lighting Unit 101: Object plane / First plane 102: Objective lens 103: Lens 200: Projection System 205: Imaging System 207: Multi-Particle Detector 208: Projection Lens 209: Projection Lens 210: Projection lens 214: Contrast Aperture 300: Beam generation equipment 301: Particle Source 303.1: Converging Lens 303.2: Converging Lens 304: Perforated plate / First perforated plate / Pre-perforated plate 305: Multi-aperture configuration / micro-optical unit / multi-beam generator / micro-optical unit 305.f: Final porous plate 306: Perforated plate 306.1: Perforated Plate / Multi-image Dispersion Plate 306.2: Perforated Plate 306.3: Perforated Plate 306.4: Perforated Plate 307: Global Lens Electrode / Global Converging Lens / Field Lens 308: Magnetic lens / Magnetic field lens / Field lens 309: Diverging particle beam / collimated particle or electron beam 310: Perforated plate / Final perforated plate 321: Surface 323: Focal Point / Bundle Focal Point 350: Perforated plate 350.1: Perforated Plate 350.2: Perforated plate 350.3: Perforated Plate 350.f: Final porous plate 351: Hole / Opening / Round Hole 351.1: Hole / Opening 351.2: Hole / Opening 351.3: Hole / Opening 351.c: Center Hole 360: board 360.1: Board / First Board 360.2: Board / Second Board 360.3: Plate / Third Plate / Membrane 360.4: Plate / Film 360.5: Plate / Film 360.6: Plate / Film 361: Coarse pores 362: Coarse pores 362.1: Coarse pores 362.2: Coarse pores 362.3: Coarse pores 363: Conductive area / opening 363.1: Opening 363.2: Opening 363.3: Opening 370.1: Spacer 370.2: Spacer 380: Frame area 381: Membrane region 382.1: Cavity 382.2: Cavity 382.3: Cavity 390:Substrate 392: First metal layer / conductive layer 393: Additional Layer 394: Metallic layer 395: Insulation layer 396: Metal layer 400: Beam splitter 500: Cluster Deflection System 700: Magnetic Lens 701: Magnetic Field 900: Drilling components 901: Substrate element 902: Electrode 910: Negative Modulus 911: Kong 3a: Particle beam 3b: Particle beam / axis beam 3c: Particle beam Ax geometric principal axis B: Distance / Magnetic Field Bz: z-component / magnetic field C: Thickness D: Plate spacing d1: Distance dFF: Distance E: Focal plane F: Focus FIB: Focused Ion Beam G: Object H: Thickness / Height L: Vertical axis M: Center S1: Method and Steps S2: Method and Steps S3: Method and Steps S4: Method and Steps S5: Method and Steps S11: Steps S12: Steps S13: Methods and Steps S14: Methods and Steps U1: Voltage U2: Voltage U3: Voltage Z: Axis

Claims

1. A method for manufacturing a micro-optical unit for a multi-particle beam system, comprising the following steps: (a) providing a first plate of the micro-optical unit, the first plate being conductive; (b) providing a second plate of the micro-optical unit, the second plate being conductive; (c) forming a plate stack comprising the step of stacking the first plate of the micro-optical unit and the second plate of the micro-optical unit on top of each other, wherein the first plate of the micro-optical unit and the second plate of the micro-optical unit are fixed relative to each other in the plate stack and electrically insulated from each other; and (d) penetrating the entire plate stack formed having at least the first plate and the second plate of the micro-optical unit, thereby forming a first plurality of holes in the first plate of the micro-optical unit and a second plurality of holes in the second plate of the micro-optical unit.

2. The method as described in claim 1, wherein the first plate of the micro-optical unit and / or the second plate of the micro-optical unit are metal.

3. The method as claimed in claim 1, wherein the plate stack further includes at least one additional plate of the micro-optical unit and / or at least one third plate, the third plate being conductive, and wherein the third plate of the micro-optical unit is fixed and electrically insulated relative to the first plate and the second plate of the micro-optical unit, and wherein, while performing method step (d), the third plate of the micro-optical unit is also penetrated, thereby creating a third plurality of holes in the third plate of the micro-optical unit.

4. The method as described in claim 3, wherein the third plate of the micro-optical unit is metal.

5. The method as described in claim 3, wherein the first plate and / or the second plate and / or the third plate are magnetically permeable; and wherein the following relationship applies to the relative permeability μr of the plate material of the first plate and / or the second plate and / or the third plate: μr ≥ 1000, particularly μr ≥ 10000 or μr ≥ 15000.

6. The method as described in any one of claims 1 to 5, wherein in step (d) the board stack is penetrated through a laser drill.

7. The method as described in any one of claims 1 to 5, wherein the board stack is penetrated by micro-discharge processing in step (d).

8. The method as described in any one of claims 1 to 5, wherein in step (d) the board stack is penetrated by a high-speed mechanical micro-drill.

9. The method as described in any one of claims 1 to 5, wherein in step (d), the board stack is penetrated by vibratory drilling or ultrasonic drilling.

10. The method as described in any one of claims 1 to 5, wherein a focused ion beam (FIB) is used in step (d) to penetrate the plate stack.

11. The method as described in any one of claims 1 to 5, wherein at least one of the plurality of plates in the plate stack comprises an insulating material as a substrate material, particularly ceramic, and wherein the method further comprises the following steps, which are temporarily performed before method steps (a) to (d): (e) forming a plurality of coarse holes in the at least one plate having an insulating material as the substrate material; and (f) metallizing the coarse holes; wherein a subsequent implementation of method step (d) penetrates the metallized coarse holes and thus forms the plurality of holes.

12. The method as described in claim 11, wherein the coarse holes are metallized by sputtering and / or by electroplating.

13. The method as described in any one of claims 1 to 5, wherein the plurality of holes in the plurality of stacked plates are formed simultaneously in method step (d).

14. The method as described in any one of claims 1 to 5, wherein the plurality of holes in the plurality of plates of the plate stack are formed sequentially in method step (d).

15. The method as described in any one of claims 1 to 5, wherein each of the plurality of holes has a diameter A, which is subject to the following relationship: 40 μm ≦ A ≦ 400 μm, particularly 80 μm ≦ A ≦ 400 μm or 110 μm ≦ A ≦ 400 μm.

16. The method as described in claim 15, wherein the holes in the plurality of stacked plates are circular, elliptical, n-folded, or irregular in shape.

17. The method as described in any one of claims 1 to 5, wherein adjacent holes in a plurality of stacked plates have a distance B, which is subject to the following relationship: 70 μm ≦ B ≦ 400 μm, particularly 90 μm ≦ B ≦ 400 μm or 120 μm ≦ B ≦ 400 μm.

18. The method as described in any one of claims 1 to 5, wherein the following relationship applies to the thickness C of one of the plates in the plate stack: 20 μm ≦ C ≦ 500 μm, particularly 150 μm ≦ C ≦ 500 μm or 250 μm ≦ C ≦ 500 μm.

19. The method as described in any one of claims 1 to 5, wherein the following relationship applies to the board spacing D between adjacent boards in the board stack: 1 μm ≦D ≦100 μm, particularly 20 μm ≦D ≦100 μm or 40 μm ≦D ≦100 μm.

20. The method as described in any one of claims 1 to 5, wherein the following relationship applies to the total height H of the board stack: 50 μm ≦ H ≦ 1000 μm, particularly 300 μm ≦ H ≦ 1000 μm or 500 μm ≦ H ≦ 1000 μm.

21. The method as described in any one of claims 1 to 5, further comprising the following steps: after penetration according to step (d), flushing the plate stack through a plurality of flushing holes in the first plate and the second plate of the micro-optical unit to remove drilling material, wherein the following relationship applies to the diameter S of the flushing holes relative to the diameter A of the holes in the first plate and the second plate of the micro-optical unit: S ≥ 10A, in particular S ≥ 100A.

22. The method as claimed in claim 21 further comprises the following steps: filling the intermediate space between the first plate of the micro-optical unit and the second plate of the micro-optical unit with a rinsing agent prior to penetration according to step (d); cooling the rinsing agent and thus solidifying the rinsing agent; heating the rinsing agent after penetration according to step (d) and thereby liquefying the rinsing agent; and removing the rinsing agent from the intermediate space.

23. The method as described in claim 5 further includes the following steps: annealing the board stack after penetration according to step (d).

24. The method as described in any one of claims 1 to 5, wherein the micro-optical unit comprises at least a second plate stack or an additional plate stack.

25. The method as described in claim 24, wherein the second plate stack or additional plate stack of the micro-optical unit is formed by method steps (a) to (d); or wherein the second plate stack or additional plate stack of the micro-optical unit is formed by a planar process and / or lithography method.

26. The method as described in claim 25, wherein the method further comprises the following method steps: (g) aligning the first plate stack and the second plate stack or another plate stack with each other.

27. A micro-optical unit for a multi-particle beam system, manufactured according to the method described in claim 1.

28. A micro-optical unit for a multi-particle beam system, wherein the micro-optical unit comprises a first porous plate made of metal and a second porous plate made of metal, wherein the following relationship applies to the aperture A of the first porous plate and the second porous plate: A ≥ 150 μm, wherein the following relationship applies to the thickness C of the first porous plate and the second porous plate: C ≥ 250 μm; and wherein the following relationship applies to the plate spacing D between the first porous plate and the second porous plate: D ≥ 30 μm.

29. A multi-particle beam system, particularly a multi-particle microscope, having micro-optical units as described in any one of claims 27 and 28.

30. A multi-particle beam system as claimed in claim 29, wherein a voltage U, wherein U ≥ 250V, particularly U ≥ 300V or U ≥ 350V, is applied to a first porous plate and / or a second porous plate during operation of the multi-particle beam system.

31. The multi-particle beam system as claimed in claim 29, further comprising a magnetic lens disposed downstream of the micro-optical unit relative to the particle optical beam path of the multi-particle beam system during operation of the multi-particle beam system, wherein, Relative to the particle optical beam path of the multi-particle beam system, the micro-optical unit has a magnetically permeable final porous plate, wherein the following relationship applies to the relative permeability μr of the material of the final porous plate: μr ≥ 1000, particularly μr ≥ 10000 or μr ≥ 15000; and wherein, during operation of the multi-particle beam system, the final porous plate of the micro-optical unit is disposed within a magnetic field formed by the magnetic lens.

32. The multi-particle beam system as claimed in claim 31 further includes a controller configured to control the magnetic lens and set its magnetic field strength, wherein the controller is further configured such that the azimuth tilt of individual particle beams passing through the magnetic lens during operation is set by changing the magnetic field strength of the magnetic lens.

33. A multi-particle beam system as described in any one of claims 31 to 32, wherein the material of the final porous plate is Permenorm®.

34. A multi-particle beam system comprising: a particle source for forming a charged particle beam; a multi-beam generator through which the charged particle beam forms a plurality of first separately charged particle beams, the first separately charged particle beams forming a first field; a first particle optics unit having a first particle optical beam path configured to image the formed first separately charged particle beams onto an object plane such that the first separately charged particle beams strike the object at an incident position forming a second field; an objective lens, particularly a magnetic objective lens, through which the first separately charged particle beams pass; and a controller; wherein the multi-beam generator includes a micro-optics unit having a plurality of successively arranged porous plates, wherein, in each case, the first separately charged particle beams pass continuously through the porous plates, wherein... Relative to the particle optical beam path, the micro-optical unit includes a magnetically permeable final porous plate, wherein the following relationship applies to the relative permeability μr of the material of the final porous plate: μr ≥ 1000, particularly μr ≥ 10000 or μr ≥ 15000, wherein the first particle optical unit includes a magnetic field lens, wherein during operation of the multi-particle beam system, the final porous plate of the micro-optical unit is disposed within a magnetic field formed by the magnetic field lens, wherein the controller is configured to control the magnetic field lens and set its magnetic field strength, and wherein the controller is further configured to set the azimuth tilt of the first separately charged particle beams when impacting the object and / or passing through the objective lens by means of the change in the magnetic field strength of the magnetic field lens.

35. The multi-particle beam system as claimed in claim 34, wherein the central hole of the final porous plate and the magnetic field lens are configured to be centered on each other.

36. A multi-particle beam system as claimed in any of claims 34 to 35, wherein the z-component Bz of the magnetic field B on the particle optical axis Z has a value at the final porous plate, which is subject to the following relationship: 0.1 mT ≦ Bz ≦ 10.0 mT, and in particular 1.0 mT ≦ Bz ≦ 10.0 mT.

37. A multi-particle beam system as described in any of claims 34 to 35, wherein, in order to set the azimuth tilt of the first separately charged particle beams, the magnetic field strength Bz of the magnetic field lens is changed by a maximum plus or minus 50% of its nominal value.

38. A multi-particle beam system as described in any one of claims 34 to 35, wherein the material of the final porous plate is Permenorm®.

39. A multi-particle beam system as described in any one of claims 34 to 35, wherein the multi-particle beam system is a multi-beam particle microscope.

40. The multi-particle beam system as claimed in any one of claims 34 to 35, further comprising: a detection system having a plurality of detection regions forming a third field; a second particle optics unit having a second particle optics beam path configured to image a second individual charged particle beam emitted from an incident position in the second field onto the third field of the plurality of detection regions of the detection system; and a beam splitter disposed in the first particle optics beam path between the multi-particle source and the objective lens, and disposed in the second particle optics beam path between the objective lens and the detection system; wherein both the first individual charged particle beam and the second individual charged particle beam pass through the objective lens.

41. The multi-particle beam system as claimed in claim 40, wherein a second micro-optical unit having a plurality of consecutively arranged porous plates is disposed in the second particle optical beam path, the second separately charged particle beam passing continuously through the porous plates, wherein, Relative to the particle optical beam path, the micro-optical unit includes a magnetically permeable final porous plate, wherein the following relationship applies to the relative permeability μr of the final porous plate material: μr ≥ 1000, particularly μr ≥ 10000 or μr ≥ 15000, wherein the second particle optical unit includes a magnetic projection lens, wherein during operation of the multi-particle beam system, the final porous plate of the second micro-optical unit is disposed within a magnetic field formed by the magnetic projection lens, wherein the controller is configured to control the magnetic projection lens and set its magnetic field strength, and wherein the controller is further configured to set the azimuth tilt of the second charged particle beam when it impacts the detection area and / or when it passes through a contrast aperture horizontally arranged with the second charged particle beam by means of the change in the magnetic field strength of the magnetic projection lens.

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