Method of manufacturing a micro-optical unit for a multi-particle beam system, micro-optical unit and multi-particle beam system

Abstract

The present invention relates to a method for manufacturing a micro-optical unit for a multi-particle beam system, comprising the steps of: (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) creating 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) piercing the entire created plate stack having at least the first plate and the second plate of the micro-optical unit, thereby creating 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 generally relates to multi-particle beam systems, and more specifically to multi-beam particle microscopes operating using multiple separate charged particle beams. In particular, 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. Background Technology

[0002] With the continuous development of increasingly smaller and more complex microstructures, such as semiconductor components, there is a need for further development and optimization of planar fabrication technologies and inspection systems for the production and inspection of small-sized microstructures. For example, the development and production of semiconductor components requires monitoring and testing the design of wafers, and planar fabrication technologies require process optimization to achieve reliable production with 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 an inspection apparatus capable of high throughput to inspect microstructures on wafers with high precision.

[0003] Typical silicon wafers used in the production of semiconductor components have diameters up to 300 mm. Each wafer is divided into 30 to 60 repeating regions (“dies”), with dimensions up to 800 mm. 2 Semiconductor devices comprise multiple semiconductor structures fabricated in layers on the surface of a wafer using planar integration techniques. Due to the manufacturing process, semiconductor wafers typically have planar surfaces. In this context, the structural dimensions of integrated semiconductor structures range from a few μm to a critical size (CD) of a few nanometers, and these dimensions are expected to become even smaller in the near future; it is anticipated that future structural dimensions, or critical sizes (CD), will correspond to process nodes of 3 nm, 2 nm, or even smaller according to the International Technology Roadmap for Semiconductors (ITRS). With these small structural dimensions, defects on the order of the critical size must be rapidly identified over very large areas. For many applications, specifications regarding the accuracy of measurements provided by inspection equipment are even higher, for example, by a factor of two or an order of magnitude. For instance, the width of semiconductor features must be measured with an accuracy better than 1 nm (e.g., 0.3 nm or even smaller), and the relative positions of semiconductor structures must be determined with a superposition accuracy better than 1 nm (e.g., 0.3 nm or even smaller).

[0004] MSEM (a type of multi-beam scanning electron microscope) is a relatively recent development in the field of charged particle systems (“charged particle microscopy”, CPM). For example, a multi-beam scanning electron microscope is disclosed in US 7,244,949 B2 and US 2019 / 0355544 A1. In the case of a multi-beam electron microscope or MSEM, the sample is simultaneously irradiated by multiple individual electron beams arranged in a field or grating. For example, 4 to 10,000 individual electron beams can be provided as primary radiation, with each individual electron beam spaced 1 to 200 micrometers apart from adjacent individual electron beams. For example, an MSEM may have approximately 100 separate individual electron beams (“sub-beams”), arranged, for example, in a hexagonal grating, with the individual electron beams separated by a pitch of approximately 10 μm. The multiple 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 may be a semiconductor wafer fixed to a wafer holder mounted on a movable stage. When a wafer surface is irradiated by a primary beam of individually charged particles, interaction products (such as secondary electrons or backscattered electrons) are emitted from the wafer surface. Their origin points correspond to the locations on the sample where the multiple primary beams are focused in each case. The amount and energy of the interaction products depend on the material composition and the morphology of the wafer surface. These interaction products form multiple secondary beams of individual particles, which are collected by a common objective and, after passing through a projection imaging system of a multi-beam inspection system, are incident on a detector arranged in a detection plane. The detector comprises multiple detection regions, each containing several detection pixels, and captures the intensity distribution of each secondary beam of individual particles. An image field of, for example, 100 μm × 100 μm is obtained in this process.

[0005] Prior art multibeam electron microscopes include a series of electrostatic and magnetic elements. At least some of these electrostatic and magnetic elements can be configured to adjust the focusing position and astigmatism of multiple individual charged particle beams. Prior art multibeam systems with charged particles also include at least one intersecting plane of primary or secondary individual charged particle beams. Furthermore, prior art systems include a detection system for ease of setup. Prior art multibeam particle microscopes include at least one beam deflector (“deflection scanner”) for collectively scanning an area of ​​the sample surface with multiple primary individual particle beams to obtain an image field of the sample surface.

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

[0007] In the case of multi-beam systems, a distinction is generally made between systems operating with a single column and systems operating with multiple columns. In a system with a single column, individual particle beams pass at least partially through the same particle optics unit or through one or more global particle lenses. Additionally, within a single column, the individual particle beams are relatively close to each other. Despite the presence of partially global particle optics, even in the case of a single column, individual controllability and / or shapeability of individual particle beams are required to correct imaging aberrations such as field curvature, field astigmatism, and other aberrations. So-called micro-optics units can be used for this individual effect and / or shaping of individual particle beams. Micro-optics units are also commonly referred to as multi-beam particle generators for generating and shaping multiple individual particle beams. Multi-beam particle generators or micro-optics units comprise a sequence of several perforated plates that can be used for active beam shaping, or at least one of the perforated plates can be used for active beam shaping. For example, electrodes that can be collectively or individually controlled can be provided in the regions of the perforations for this purpose. These can be, for example, annular electrodes or multi-pole electrodes. According to another example, the porous plate can have a monolithic embodiment in which a voltage is applied uniformly to the porous plate, i.e., the monolithic porous plate is then at a certain potential, so that its openings can produce a lensing effect in interaction with other particle optics elements. Other configurations of the porous plate for active beamforming are also possible.

[0008] For optimal individual particle beam shaping / individual particle beam effects, 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 on top of each other. Furthermore, the apertures in known porous plates are relatively small, for example, each aperture diameter is less than 100 μm, such as only 90 μm or less. These two conditions—the small aperture diameter and the precise alignment of the apertures / electrodes, including control—can be met by using MEMS technology to fabricate micro-optical units. In other words, processes similar to those used in semiconductor manufacturing are used to produce micro-optical units or their porous plates.

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

[0010] While the production of micro-optical units using MEMS technology is highly precise, this type of production still has drawbacks: the development time for micro-optical unit production is relatively long, typically ranging from six months to three-quarters of a year. Changes to the production process are only possible under difficult circumstances or over a considerable period. Furthermore, generally only a few semiconductor manufacturers are involved, semiconductor manufacturing process control is challenging, and semiconductor manufacturing requires very expensive equipment. Summary of the Invention

[0011] Therefore, the problem to be solved by the present 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 should not sacrifice the quality of the micro-optical unit or degrade the achievable resolution in the multi-particle beam system. Furthermore, the method should be easy to implement and cost-effective.

[0012] This problem is addressed by the subject matter of the independent claims. Advantageous embodiments of the invention will be apparent from the dependent 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 based on two fundamental insights:

[0015] (1) It has been found that silicon, the material used for micro-optical units, can cause serious problems: for example, undesirable surface potentials may appear, and the conductivity of silicon may change over time. Both have undesirable effects on individual charged particle beams as they pass through the micro-optical unit, and therefore on beam quality, and thus on the resolution achievable during operation of a multi-particle beam system.

[0016] (2) Furthermore, it has been surprisingly found that the expectation / trend for further miniaturization of micro-optical units for the purpose of improving resolution is not always correct or necessary. Instead, real advantages can be identified when producing micro-optical units with slightly larger dimensions, such as larger apertures and / or thicker aperture plates. In particular, advantages are provided due to reduced parasitic effects, such as reduced beam deflection when the desired electro-optical effects are comparable, and because of the higher voltage that can be applied to the aperture plates of the micro-optical unit. In particular, the latter is of particular interest for increasingly more individual particle beams and, in the case of micro-optical units, for increasingly larger image fields.

[0017] Therefore, the basic concept of this invention is to use alternative manufacturing processes to replace MEMS technology, particularly those applicable to metalworking. The fact that such metalworking processes tend to be used only to produce slightly larger structures is not necessarily a disadvantage in this case. On the contrary, the advantage offered by metalworking processes is that silicon no longer has 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, the problem of precisely aligning the porous plates with each other can also be solved with skilled procedures, precisely, independently of their material or optical or IR transparency; in this case, the porous plates are automatically or inherently aligned correctly with each other.

[0018] 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:

[0019] (a) A first plate providing the micro-optical unit, which is conductive;

[0020] (b) A second plate for providing the micro-optical unit is conductive;

[0021] (c) Creating a plate stack comprising the step of stacking a first plate of a micro-optical unit and a second plate of a 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 are electrically isolated from each other; and

[0022] (d) Puncture the entire created plate stack having at least a first plate and a second plate with micro-optical units, thereby creating a first plurality of holes in the first plate of the micro-optical units and a second plurality of holes in the second plate of the micro-optical units.

[0023] Similar to the introduction of this specification, the term "micro-optical unit" should be understood as a sequence of multiple porous plates, wherein at least one porous plate is used during operation for active beamforming of multiple individual particle beams in a multi-particle beam system. Preferably, each aperture is through which exactly one individual particle beam passes.

[0024] Claim 1 did not originally refer to a porous plate, but rather to a first plate and a second plate of the micro-optical unit. This is due to the fact that the holes in the first and second plates are formed only during the manufacturing process.

[0025] The first plate of the micro-optical unit is conductive. This conductivity can extend to the entire first plate or only to a portion of it. The same applies to the second plate. Conductivity is essential for the ability to manufacture micro-optical units for multi-particle beam systems, even using many methods known in metalworking. This will be explained in detail below.

[0026] The creation of the plate stack includes the step of stacking a first plate and a second plate of a 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 and electrically isolated from each other in the plate stack. Fixing and electrical insulation can be achieved simultaneously and / or by the same means, but different means 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.

[0027] The plate stack comprises at least a first plate and a second plate of micro-optical units. However, the plate stack may also include additional plates of micro-optical units. In any case, method step (d) achieves the following: piercing the entire created plate stack, which has at least the first and second plates of micro-optical units, thereby creating a first plurality of holes in the first plate of the micro-optical units and a second plurality of holes in the second plate of the micro-optical units. Thus, holes that should be passed through by the same individual particle beam during operation of the micro-optical unit or multi-particle beam system are generated in the same method step or during the same piercing event. Thus, when the piercing is performed accordingly precisely by a drilling device, the mutually allocated holes in the first and second plates of the micro-optical units, and optionally one or more additional plates of the micro-optical units, are automatically and correctly aligned with each other.

[0028] According to a preferred embodiment of the invention, the first plate and / or the second plate of the micro-optical unit are metallic. 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 treatment, such as gold plating. Alternatively, the first plate and / or the second plate of the micro-optical unit may also be made of a semiconductor material. For example, the semiconductor material may include silicon.

[0029] According to another preferred embodiment of the invention, the plate stack further includes at least one additional plate, and thus includes at least a third plate of the micro-optical unit, which is conductive. In this case, the third plate of the micro-optical unit is fixed relative to the first plate and the second plate of the micro-optical unit, and is electrically isolated from them in each case. During the execution of method step (d), the third plate of the micro-optical unit is also punctured, thus creating a third plurality of holes in the third plate of the micro-optical unit. Therefore, these third plurality of holes are also inherently correctly aligned with the other holes in the first and second plates.

[0030] 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, particularly the same metal; however, this is not necessarily the case.

[0031] 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. Furthermore, the following relationship (in each case) applies to the relative permeability μ of the plate materials. r μ r ≥1000, preferably μ r ≥ 10000 or μ r ≥ 15000.

[0032] The magnetic permeability of one, several, or even all of the plates enables the expansion of the application areas or potential uses of the micro-optical unit. For example, plates or a series of plates in the micro-optical unit are used to set a focus. Magnetic guide plates, particularly the final porous plates regarding the particle beam path during operation of the micro-optical unit, can also be combined with downstream magnetic lenses to achieve the function of multiple deflectors: for such applications, the final porous plate is arranged within the magnetic field of the downstream magnetic lens, or may be arranged within the magnetic field of the downstream magnetic lens. Specific configurations of such multiple deflectors will be discussed in further detail below during the course of this patent application.

[0033] Various relative permeability μ exists in the existing technology. r Magnetic materials with a strength ≥ 1000. These specifically include standard soft magnetic materials, such as pure iron (e.g., Vacofer). ® Nickel-iron alloys with a nickel content of approximately 75%, such as high-permeability nickel-iron alloys, permalloy, or super-permalloy; nickel-iron alloys with a nickel content of approximately 50%, such as Permenorm. ® Cobalt-iron alloys with a cobalt content of approximately 50%, 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 such materials are, in principle, suitable for use in the method according to the invention for manufacturing micro-optical units for multi-particle beam systems.

[0034] According to a preferred embodiment of the invention, in step (d), the plate stack is pierced by laser drilling. Laser drilling is a non-mechanical thermal separation method. Various types of laser drilling techniques exist, such as single-pulse drilling, impact drilling, piercing, and helical drilling. Single-pulse drilling is the fastest; it "shoots" the material through a single pulse. Impact drilling involves placing multiple pulses at the same point to laser-drill a hole through the material. Piercing refers to cutting a hole by following the drill profile after a through hole has already been formed. Helical drilling may require special optics. At a basic level, the accuracy of the drilling and the smoothness of the drilled hole walls depend on the material being pierced and the type of laser radiation. For example, copper absorbs green and blue radiation very well, but not so well with ordinary infrared radiation. Today, laser drilling methods are very fast and very efficient: for example, 200 holes per second can be drilled on a 1 mm thick titanium sheet using single-pulse micro-drilling. For example, the focal diameter of the laser used is 12 μm, and the diameter of the resulting drilled holes is only 80 μm. When created using MEMS technology, an 80 μm hole diameter already corresponds to the size of holes used in existing technologies. Therefore, laser drilling can be used to manufacture very small holes—if needed—and much larger holes—if needed, using other laser drilling techniques. Furthermore, the method is very fast. Additionally, as a manufacturing method, laser drilling offers the advantage that the material to be pierced does not necessarily have to be metallic or even conductive. Insulators can also be pierced by laser drilling. Therefore, in laser drilling, even a stack of plates with a series of conductive and electrically insulating plates can be pierced in one go or with the same laser pulse or multiple identical laser pulses.

[0035] According to another preferred embodiment of the invention, the plate stack is pierced by micro-EDM in step (d). Micro-EDM, or micro-spark etching, is a form of EDM (electrical discharge machining) and can be described as a combination of drilling etching and sinking etching techniques. This technique, based on spark etching as a machining method, is well-suited for machining conductive materials of varying hardness into the correct shape at high speed and with high precision.

[0036] EDM is a non-contact method that allows for the removal of material over very short lengths without inducing mechanical stress within the material. The material is shaped through highly localized melting and evaporation due to a discharge between the electrode and the material being treated. The discharge, forming tiny plasma channels at temperatures up to 10,000°C, locally melts very small amounts of material. If the current is interrupted, the generated plasma collapses, and the resulting vacuum pulls the molten material into the surrounding dielectric. For the discharge to occur, the material must possess sufficient conductivity; material hardness is irrelevant. Therefore, in principle, all metals and many semiconductors are suitable for EDM, as are micro-EDM.

[0037] Micro-EDM is a special form of EDM where the workpiece can have features as small as approximately 10 μm. These tiny features are achieved using equally small electrodes. Therefore, micro-EDM can also be used to easily obtain apertures on the order of those already used in micro-optical units. Furthermore, micro-EDM processes are significantly faster than planar integration techniques.

[0038] According to a preferred embodiment of the invention, in step (d), the plate stack is pierced 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.

[0039] According to a preferred embodiment of the invention, in step (d), the plate stack is pierced by means of vibratory drilling or ultrasonic drilling. The principle of vibratory drilling is that axial vibration or oscillation is generated in addition to the feed motion of the drill bit, so that drill chips can be broken and then easily removed from the cutting area. A distinction is made between self-sustaining vibration systems and forced vibration systems. In vibratory drilling with inherent vibration, the tool's natural frequency is utilized to cause it to vibrate naturally during cutting. The vibration can be maintained by a mass spring system in the tool holder itself. Another option is to use a piezoelectric system to generate and control the vibration. These systems allow for high vibration frequencies (up to 2 kHz) with small dimensions (a few μm) and are particularly suitable for drilling small holes.

[0040] Ultrasonic drilling uses oscillations within the ultrasonic range to create a hole. This is a machining method for materials that does not rely on rotary machining. It is particularly useful for hard and brittle materials. The drilling tool is set to vibrate in the feed direction by ultrasonic waves generated in an ultrasonic transducer, which also stimulates the vibration of particles in the supplied abrasive suspension. During a small portion of the oscillation cycle, the workpiece is removed in a micro-region. Conventional drilling can also be supplemented by the additional use of ultrasound to improve operating parameters.

[0041] According to a preferred embodiment of the invention, a focused ion beam (FIB) is used to pierce 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 micron and nanometer processing and can modify or process materials in the micron and nanometer range. For example, gallium ions are used as the focused ions, but other ions can also be used. The use of a focused ion beam even allows for milling features in the 10 to 15 nm range; milling of features in the micron range is entirely and comprehensively possible. One problem with applying a focused ion beam is its relatively shallow focusing depth. Therefore, it may be difficult to pierce a thick plate or a thick plate stack in one go. However, even in this case, there are solutions, such as dividing the plate stack into several sub-stacks and then using the FIB to pierce the sub-stacks separately, especially at lens transitions, where precise alignment of the holes in the different plates is critical. The sub-stacks can then be assembled into a single stack.

[0042] In the above-described drilling method, the material removed by piercing must be removed from the plate stack. According to a preferred embodiment of the invention, flushing holes can therefore be provided, or have already been provided, in the plates of the plate stack, having a larger diameter than the holes in the first and second plates of the micro-optical unit. These flushing holes can be produced by the same or other methods relative to the holes in the first and second plates of the micro-optical unit; the method itself is not decisive here. Rather, it is important that the diameter of the flushing holes is chosen in such a way that the removed material can be removed or flushed out through these flushing holes during the flushing operation in the processing chamber after piercing the plate stack. 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 laser drilling or after using a focused ion beam.

[0043] The flushing holes also allow for the subsequent removal or flushing away of any auxiliary materials that might be used in the production of the board stack / micro-optical unit. For example, liquid can be introduced between the boards of the board stack before the mechanical drilling process, and then the liquid can be cooled to solidify before piercing the board stack. As a result, the forces acting during piercing can also be absorbed by the solidified liquid. After piercing, the board stack can be reheated, the solidified liquid / solid can be liquefied again, and then flushed out through the flushing holes.

[0044] According to a preferred embodiment of the present invention, the method further includes the following steps: after perforation according to step d), flushing the plate stack and removing the drilled material through flushing holes in the first plate and the second plate of the micro-optical unit, wherein the diameter S of the flushing hole is subject to the following relationship with respect to the diameter A of the hole in the first plate and the second plate of the micro-optical unit: S ≥ 10A, preferably S ≥ 100A.

[0045] According to another preferred embodiment of the present invention, the method further includes the following steps:

[0046] Before puncture according to step d).

[0047] - Fill the space between the first plate and the second plate of the micro-optical unit with rinsing agent, and

[0048] - Cooling the rinsing agent and thus solidifying it; and

[0049] After piercing according to step d).

[0050] - Heating the flushing agent to liquefy it; and

[0051] - Remove the flushing agent from the intermediate space.

[0052] The above-mentioned flushing holes can be used to fill and remove flushing fluid.

[0053] According to another preferred embodiment of the present invention, the method further includes the following step: after puncture according to step d).

[0054] - Anneal the stack of plates.

[0055] Annealing of the plate stack is used to restore the soft magnetic properties or high permeability of the magnetic plates. Voltage or vibrations that may occur in the method according to the invention for manufacturing micro-optical units for multi-particle beam systems can reduce the permeability to the point that the desired effect, such as multiple deflections of individual particle beams, can no longer be achieved through the plates. 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 plate stack can also withstand the high temperatures of the annealing process. In principle, this can be ensured by making appropriate material selections for the insulators.

[0056] According to another preferred embodiment of the invention, at least one plate in the plate stack comprises an insulating material as a substrate material, particularly ceramic, and the method further comprises the following steps, which are performed in time prior to method steps (a) to (d):

[0057] (e) A plurality of coarse pores are formed in at least one plate having an insulating material as a substrate; and

[0058] (f) Metallized coarse pores;

[0059] In this process, the subsequent implementation of step (d) involves piercing the metallized coarse hole and thus forming multiple holes.

[0060] Therefore, in this exemplary embodiment, not the entire plate of the plate stack is conductive, but only a portion of it, particularly the metallized region around the coarse holes. This is sufficient to perform all material processing methods that require the conductivity of the material to be pierced. Naturally, the diameter of the coarse holes is larger than the diameter of the holes in the finished porous plate. In contrast, the metallized coarse holes are smaller in diameter than the diameter of the full holes in the porous plate.

[0061] According to a preferred embodiment of the invention, the coarse holes are metallized by sputtering and / or by electroplating.

[0062] According to a preferred embodiment of the invention, multiple holes in the boards of a board stack are simultaneously generated in method step (d). For this purpose, multiple drilling devices can be used simultaneously. These can be, for example, multiple laser pulses during laser drilling, or multiple electrodes (so-called "Manhattan electrodes") that are fixedly oriented relative to each other in a micro-EDM method. This type of simultaneous drilling is very fast.

[0063] According to an alternative embodiment of the invention, multiple holes in the plates of the plate stack are continuously generated in method step (d). This means that the entire plate stack is first completely pierced at a first point, then completely pierced at a second point, and so on. In this variant of the embodiment, the drilling method used is relatively simple.

[0064] According to a preferred embodiment of the invention, each of the plurality of holes has a diameter A, wherein the following applies: 40 μm ≤ A ≤ 400 μm, preferably 80 μm ≤ A ≤ 400 μm or 110 μm ≤ A ≤ 400 μm. For circular holes, the diameter naturally corresponds to twice the radius. In the case of holes of different shapes (e.g., elliptical holes), the minimum possible distance between the hole walls is defined as the diameter A. In the case of an ellipse, this therefore corresponds to twice the semi-minor axis. In the case of stepped holes, which can be produced, for example, by a stepped electrode or by several drilling steps (e.g., first piercing the plate with a small drilling device, then partially drilling it open with a larger drilling device), the diameter A refers to the minimum diameter.

[0065] According to a preferred embodiment of the invention, the holes in the plates of the plate stack have circular, elliptical, n-fold, or irregular shapes. In this respect, the method according to the invention is very flexible.

[0066] According to a preferred embodiment of the present invention, the centers of adjacent holes in the plates of the plate stack have a distance B, which is suitable as follows: 70 μm ≤ B ≤ 400 μm, preferably 90 μm ≤ B ≤ 400 μm or 120 μm ≤ B ≤ 400 μm.

[0067] According to a preferred embodiment of the present invention, the following applies to the thickness C of the plates in the plate stack: 20 μm ≤ C ≤ 500 μm, preferably 150 μm ≤ C ≤ 500 μm or 250 μm ≤ C ≤ 500 μm.

[0068] According to a preferred embodiment of the present invention, the following applies to the plate distance D between directly adjacent plates in a plate stack: 1 μm ≤ D ≤ 100 μm, preferably 20 μm ≤ D ≤ 100 μm or 40 μm ≤ D ≤ 100 μm.

[0069] According to a preferred embodiment of the present invention, the following 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.

[0070] Therefore, the method according to the invention is also capable of piercing relatively thick and relatively distant plates, particularly through a fast and precise method. Especially in the case of larger sizes, the production process using known planar integration techniques is much slower.

[0071] According to a preferred embodiment of the invention, the micro-optical unit includes at least a second or additional plate stack. In this case, the second or additional plate stack of the micro-optical unit can be created by means of method steps (a) to (d). However, it is also possible that the second or additional plate stack of the micro-optical unit is created or has been created by means of planar processes and / or photolithography methods. In principle, other manufacturing methods are also possible.

[0072] According to another preferred embodiment of the invention, the first plate stack and the second or additional plate stack are aligned with each other in method step (g). If several plate stacks are aligned with each other, a high degree of precision is required. However, such retrospective alignment of the plate stacks or the holes contained therein is naturally less precise than the inherently precise positioning of the holes within the plate stacks if the associated holes are precisely produced by the same method steps. Therefore, it is advantageous to provide alignment of the plate stacks with each other at those transitions between different plate stacks, as these transitions are more immune to misalignment from an electro-optical perspective. In this case, refer again to the statements related to focused ion beam drilling. In principle, the sub-stacks described in this process correspond to several stacks. In particular, the critical lens transitions should preferably belong to the same plate stack, which is preferably manufactured using the method according to the invention, including steps (a) through (d).

[0073] According to another aspect of the invention, the present invention relates to a micro-optical unit for a multi-particle beam system, which is manufactured in several embodiment variations according to the method described above.

[0074] According to another aspect of the invention, the present invention relates to a micro-optical unit for a multi-particle beam system, particularly for a multi-beam particle microscope. In this embodiment, the micro-optical unit comprises a first porous plate made of metal and a second porous plate made of metal. In each case, the following applies to the aperture diameter A of the first and second porous plates: A ≥ 150 μm. Furthermore, in each case, the following applies to the thickness C of the first and second porous plates: C ≥ 250 μm. The following applies to the plate distance D between the first and second porous plates: D ≥ 30 μm.

[0075] Therefore, the described micro-optical unit is a relatively large micro-optical unit, which is also made of metal. It is fundamentally impossible, or only possible for a considerable period of time, to manufacture such a micro-optical unit using known planar integration techniques.

[0076] According to another aspect of the invention, the present invention relates to a multi-particle beam system, particularly a multi-particle microscope, having micro-optical units as described above.

[0077] According to a preferred embodiment of the invention, during operation of the multi-particle beam system, a voltage U having U ≥ 250 V, preferably U ≥ 300 V, or U ≥ 350 V can be applied to the first and / or second porous plates of the micro-optical unit. For known micro-optical units manufactured using planar integration technology, it is generally not possible to apply such a high voltage to the porous plates. Instead, voltages on the order of less than 200 V can be used in these cases. Otherwise, flashover will occur between different porous plates. When using the aforementioned high voltages, which are sometimes significantly greater than 250 V, a relatively large plate distance 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 then particularly advantageous that the isolator can also be pierced (e.g., by laser drilling) using some of the manufacturing methods or drilling methods described according to the invention.

[0078] According to a preferred embodiment of the invention, the multi-particle beam system further includes a magnetic lens arranged downstream of the micro-optical unit relative to the particle beam path of the multi-particle beam system during operation. In this case, the micro-optical unit has a final porous plate with respect to the particle beam path of the multi-particle beam system. This final porous plate is magnetically permeable, wherein the following relationship applies to the relative permeability μ of the material of the final porous plate. r μ r ≥ 1000, preferably μ r ≥10000 or μ r ≥ 15000. In this case, during operation of the multi-particle beam system, the final porous plate of the micro-optical unit is arranged within a magnetic field generated by the magnetic lens. As a result, 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 opens up the option for setting the azimuth tilt of individual particle beams.

[0079] 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 angle tilt of the individual particle beams passing through the magnetic lens during operation by changing the magnetic field strength of the magnetic lens. This setting option is particularly useful for examining samples with high aspect ratios: when examining samples with high aspect ratios, it is often particularly important that the individual particle beams being examined are incident on the sample surface in a telecentric manner so that structures with high aspect ratios can be ideally scanned. Another exemplary application option is a sample located within the magnetic field of an objective lens system (magnetic immersion lens). Charged particles rotate or Larmor rotate in the magnetic field due to the Lorentz force. 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 is not zero when incident on the sample. This results in an azimuth angle tilt of the individual particle beams. This tilt can be compensated for by the arrangement of a final porous plate with high permeability within the magnetic field of a magnetic lens, such as a field lens.

[0080] There are also applications where a single beam of charged particles is intended to pass through, for example, an objective lens at a slight angle. This could be the case, for example, 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.

[0081] Furthermore, certain aberrations of the objective lens can be corrected, for example, by the described arrangement or by such a passive multi-deflector.

[0082] According to another preferred embodiment, the material of the final porous plate is Permenorm. ® However, other materials are also possible. These include, in particular, soft magnetic standard nickel-iron alloys with a nickel content of approximately 50%. These alloys combine high saturation magnetic flux density and high maximum permeability.

[0083] The prior art includes μ-type materials suitable for the final porous plate. r Various magnetically permeable materials with a relative permeability ≥ 1000. These materials particularly include soft magnetic standard materials, such as pure iron (e.g., Vacofer). ® Nickel-iron alloys with a nickel content of approximately 75%, such as high-permeability nickel-iron alloys, permalloy, or super-permalloy; nickel-iron alloys with a nickel content of approximately 50%, such as Permenorm. ® Cobalt-iron alloys with a cobalt content of approximately 50%, 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 thinness, plates made from this material are, in principle, suitable for use in the final porous plates.

[0084] According to another aspect of the present invention, the present invention relates to a multi-particle beam system comprising the following:

[0085] Particle source, used to generate beams of charged particles;

[0086] A multi-beam generator, through which the charged particle beam passes, thereby forming a plurality of first individual charged particle beams, the plurality of first individual charged particle beams forming a first field;

[0087] The first particle optical unit has a first particle beam path and is configured to image the generated first individual particle beam onto the object plane, such that the first individual particle beam strikes the object at the incident position where the second field is formed.

[0088] Objective lenses, especially magnetic objectives, through which the first individual particle beam passes; and

[0089] Controller;

[0090] The multi-beam generator includes a micro-optical unit having a plurality of successively arranged porous plates. In each case, the first individual charged particle beam passes successively through the porous plates. The micro-optical unit includes a magnetically permeable final porous plate relative to the particle beam path. The following relationship applies to the relative permeability μ of the material of the final porous plate. r μ r ≥ 1000, especially μ r ≥ 10000 or μ r ≥ 15000,

[0091] The first particle optical unit includes a magnetic field lens.

[0092] In this system, during operation of the multi-particle beam system, the final porous plate of the micro-optical unit is arranged within a magnetic field generated by a magnetic lens.

[0093] The controller is configured to control the magnetic field lens and set its magnetic field strength.

[0094] The controller is also configured to set the orientation of the first individual charged particle beam as it impacts an object and / or passes through the objective lens by means of changes in the magnetic field strength of the magnetic field lens.

[0095] Alternatively, the micro-optical units of the multi-beam generator can be manufactured according to the method described for manufacturing micro-optical units for multi-particle beam systems.

[0096] According to a preferred embodiment of the invention, the central hole of the final perforated plate and the magnetic field lens are arranged to be centered on each other. This centering helps to set the azimuth tilt or its accuracy.

[0097] According to another preferred embodiment of the invention, the z-component Bz of the magnetic field B on the particle optical axis Z takes a value at the final porous 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 porous plate and the lens center of the magnetic lens can be set such that the relationship of magnetic field Bz is satisfied.

[0098] According to a preferred embodiment of the invention, the magnetic field strength B of the magnetic field lens is varied by a maximum of + / - 50% of its nominal value for the purpose of setting the azimuth tilt of the first individual particle beam. Therefore, this variation in magnetic field strength is a fine-tuning. It is possible that a lookup table for different presets of magnetic field strength B (e.g., for different operating points of the multi-particle beam system) is stored in the memory of the multi-particle beam system, and this allows the azimuth tilt value of the first individual particle beam to be set specifically. In this case, a nominal value is defined such that the nominal value corresponds to a fully corrected azimuth beam tilt at the object, the sample surface, or the wafer surface.

[0099] According to a preferred embodiment of the present invention, the material of the final porous plate is Permenorm. ® However, other materials are also possible, such as other soft magnetic standard nickel-iron alloys with a nickel content of about 50%.

[0100] 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 can also be a different type of multi-particle beam system, such as a photolithography system.

[0101] According to another preferred embodiment of the present invention, the multi-particle beam system further includes the following:

[0102] A detection system having multiple detection areas that form a third field;

[0103] The second particle optical unit, having a second particle beam path, is configured to image a second, separate 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

[0104] A beam splitter is arranged in a first particle beam path between the multi-particle source and the objective lens, and in a second particle beam path between the objective lens and the detection system.

[0105] Both the first and second individual particle beams pass through the objective lens.

[0106] According to another preferred embodiment of the invention, a second micro-optical unit is provided in the second particle beam path, the second micro-optical unit having a plurality of successively arranged porous plates through which the second individual charged particle beam passes in each case. In this case, the micro-optical unit has a magnetically permeable final porous plate relative to the particle beam path, wherein the following relationship again applies to the relative permeability μ of the material of the final porous plate. r μ r ≥ 1000, preferably μ r ≥10000 or μ r ≥ 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 arranged within the magnetic field generated by the magnetic projection lens. In this embodiment of the invention, a controller is configured to control the magnetic projection lens and set its magnetic field strength. In this case, the controller is also configured such that the azimuth tilt of the second individual charged particle beam when impacting the detection region and / or passing through a contrast aperture arranged flush with the intersection point of the second individual particle beam is set by the change in the magnetic field strength of the magnetic projection lens. Furthermore, in this case, the second micro-optical unit with the final porous plate can be manufactured again using the method for manufacturing micro-optical units of a multi-particle beam system according to the invention, as described above in several embodiment variations. Utilizing the configuration of the multi-particle beam system, multiple deflectors can be implemented not only in the first particle beam path of the multi-particle beam system but also in the second particle beam path 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 beam path.

[0107] Various embodiments and aspects of the present invention may be combined with each other, in whole or in part, as long as they do not create technical contradictions. Attached Figure Description

[0108] The invention will be better understood with reference to the accompanying drawings. In the drawings:

[0109] Figure 1 A multi-particle beam system is schematically illustrated.

[0110] Figure 2 The structure of the micro-optical unit is schematically shown.

[0111] Figure 3 This schematically illustrates the alignment problem in the case of a perforated plate.

[0112] Figure 4The following diagram schematically illustrates the method steps of a method for manufacturing a micro-optical unit according to the present invention.

[0113] Figure 5 A flowchart of the manufacturing method according to the present invention is shown;

[0114] Figure 6 The following diagram schematically illustrates the method steps of the manufacturing method according to the present invention.

[0115] Figure 7 The following diagram schematically illustrates the method steps of the manufacturing method according to the present invention.

[0116] Figure 8 The following diagram schematically illustrates various aspects of the manufacturing method according to the present invention.

[0117] Figure 9 The following diagram schematically illustrates the method steps of the manufacturing method according to the present invention.

[0118] Figure 10 The diagram schematically illustrates a Manhattan electrode and the porous plate produced therefrom.

[0119] Figure 11 A porous plate for micro-optical units is schematically shown.

[0120] Figure 12 This schematically illustrates various aspects of a method for manufacturing micro-optical units.

[0121] Figure 13 Another flowchart of the manufacturing method according to the present invention is shown;

[0122] Figure 14 : This schematically illustrates particle optical imaging through symmetrical magnetic lenses and through asymmetrical magnetic lenses; and

[0123] Figure 15 The diagram schematically illustrates a device having a micro-optical unit and a magnetic lens for realizing multiple deflectors. Detailed Implementation

[0124] Figure 1A multi-beam particle microscope 1 in the form of a multi-beam particle microscope 1 is schematically shown. The multi-beam particle microscope 1 includes a beam-generating device 300 having a particle source 301 (e.g., an electron source). A diverging particle beam 309 is collimated and incident on a porous arrangement 305 formed by a series of condenser lenses 303.1 and 303.2. The porous arrangement 305 includes multiple porous plates 306 and field lenses 308. Multiple individual particle beams 3 or individual electron beams 3 are generated by the porous arrangement 305. The midpoints of the holes in the porous plate arrangement are arranged in a field that is imaged onto another field formed by a beam point 5 in the object plane 101. The spacing between the midpoints of the holes in the porous plates 306 can be, for example, 5 μm, 100 μm, and 200 μm. The diameter A of the holes is smaller than the spacing between the midpoints; examples of the diameter are 0.2 times, 0.4 times, and 0.8 times the spacing between the midpoints of the holes.

[0125] The aperture arrangement 305 and the field lens 308 are configured to generate multiple focal points 323 of the primary beam 3 in a grating arrangement on the surface 321. The surface 321 does not need to be a planar surface, but can be a spherically curved surface to take into account the field curvature of the subsequent particle optics system.

[0126] The multi-beam particle microscope 1 further includes a system of electromagnetic lenses 103 and objectives 102, which images the beam focus 323 from the intermediate image surface 325 onto the object plane 101 in a reduced size. Therein, a first individual particle beam 3 passes through a beam splitter 400 and a beam deflection system 500, through which multiple first individual particle beams 3 are deflected and the image field is scanned 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.

[0127] The object 7 to be examined can be of any desired type, such as a semiconductor wafer or a biological sample, and may include arrangements of miniaturized components, etc. The surface 15 of the object 7 is arranged 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 lens and / or an electrostatic objective lens.

[0128] Primary particles 3 incident on object 7 produce interaction products, such as secondary electrons, backscattered electrons, or primary particles that have undergone a reversal of motion for other reasons, and 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 a secondary particle beam 9. In this process, the secondary beam 9 passes through a 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, contrast stop 214, and multi-particle detector 207. The second individual particle beam 9 is located in a third field at a regular pitch at an incident position 25 on the detection region of multi-particle detector 207. Exemplary values ​​are 10 μm, 100 μm, and 200 μm.

[0129] The multibeam particle microscope 1 further includes a computer system or control unit 10, which may have a single or multiple component design and is designed to control the individual particle optics components of the multibeam particle microscope 1 and to evaluate and analyze the signals obtained by the multi-detector 207 or detection unit.

[0130] Further information relating to such a multi-beam particle system or multi-beam particle microscope 1 and its components (e.g., particle source, perforated plate, and lens) can be obtained from international patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596A1, 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.

[0131] The porous arrangement 305 forms a micro-optical unit 305, through which, in the example shown, multiple first individual particle beams 3 are initially generated at the first porous plate (so-called filter plate) and actively formed on other porous plates during operation of the multi-particle beam system 1. The micro-optical unit 305 itself can be constructed differently here.

[0132] Figure 2A micro-optical unit 305 is exemplarily shown, designed as a multi-beam generator 305. In the example shown, the multi-beam generator 305 includes a sequence of six porous plates 304, 306.1, 306.2, 306.3, 306.4, and 310 in the z-direction, corresponding to the propagation direction of individual particle beams 3. Each of the porous plates 304, 306.1 through 306.4, and 310 contains a plurality of apertures 351 through which, in each case, multiple individual particle beams 3 pass. The cross-section through the aperture 351 is shown in... Figure 2 It is not drawn to scale.

[0133] Multiple 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 provided between the final porous plate 310 and the global lens electrode 307. Multiple first individual particle beams 3 are generated during passage through the first porous plate 304, also referred to as a filter plate or pre-aperture plate, due to the incidence of collimated particles or electron beams 309. The pre-aperture plate 304 includes a metal layer 99 on its beam input side for blocking and absorbing electrons of the electron beams 309 incident thereon around the multiple apertures 85. In this case, the material of the pre-aperture plate 304 is made of a conductive material, such as doped silicon, in the example shown, and is at ground potential.

[0134] exist Figure 2 In the example shown, the next multi-aperture plate is a polyastigmatism corrector plate 306.1. The polyastigmatism corrector plate 306.1 includes multiple electrodes 82, four or more in total, for example, eight electrodes for each aperture. During operation of the multi-beam particle microscope 1, different voltages (e.g., ranging between -20 V and +20 V) can be applied to each of these electrodes, thus individually affecting each individual particle beam 3. For example, each individual particle beam 3 can be deflected up to several micrometers in each direction using an asymmetric voltage difference to pre-correct distortion of the illumination unit 100. Astigmatism pre-correction can also be performed on each individual particle beam 3. By offsetting the voltage, each multipole element can additionally function as a single lens.

[0135] In principle, the porous plates 306.2, 306.3, and 306.4 can be any desired trajectory correction plates with a monolithic design, and in the example shown, corresponding voltages V1, V2, and V3 are 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 field dependence of the correction in the trajectory correction of the individual particle beam 3.

[0136] The porous plate 310 is a double-layer porous plate and includes a plurality of annular electrodes 79 for the plurality of holes, wherein each annular electrode is configured to individually change or correct the focal position of a first individual particle beam 3 passing through it. In this case, the upper layer is insulated from the layer or sheet having the annular electrodes 79 and is made of, for example, a conductive material such as doped silicon.

[0137] The field lens 307 includes a ring electrode 84 to which a high voltage, such as 3 kV to 20 kV, or for example 12 kV to 17 kV, can be applied. In the example shown, the condenser lens 307 provides a global electrostatic lens field for globally focusing multiple individual particle beams 3.

[0138] Figure 2 The micro-optical unit 305 or its porous plate shown can, in principle, be manufactured using known manufacturing methods or planar integration techniques. 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 invention. Due to the excellent performance of such porous plates 306.2, 306.3, and 306.4 manufactured according to the invention (relatively high voltages V, V2, V3 and the applicability of relatively large plate spacing or thick spacers / isolators 83.2, 83.3, 83.4, 83.5), porous plates 310, for example, with annular electrodes 81, may also become redundant.

[0139] Figure 3 The alignment problem is illustrated in the case of perforated plates 350, which are manufactured independently of each other, i.e., independently in each case. Figure 3 A schematic illustration shows the arrangement of three panels 360 without openings. Figure 3 b schematically illustrates the use of a drilling device 900, which can in principle be of any type. Figure 3 Only this principle was considered. The direction of action of the drilling device 900 is... Figure 3 b is schematically shown by an arrow. The drilling device 900 forms an opening 351 in the plate 360, thereby allowing the porous plate 350 to emerge from the plate 360. It should be observed that, for clarity, Figure 3 Only one opening 351 is depicted, but the perforated plate 350 naturally contains several openings 351. Figure 3D now shows three porous plates 350.1, 350.2, and 350.3 assembled to form a porous arrangement 305 or a micro-optical unit 305. For this purpose, the 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 by spacers 370.1 and 370.2. The issue here is that the openings 351.1 and 351.2 and 351.3 are not precisely arranged on top of each other, i.e., not centrally arranged on top of each other. Therefore, they are not flush aligned. Achieving a precise arrangement or orientation of the openings 351.1, 351.2, and 351.3 in the porous plates 350.1, 350.2, and 350.3 relative to each other is very difficult, if not impossible. This is particularly true for the porous plates 350.1, 350.2, and 350.3, which are made of metal: this is because they do not transmit visible light or infrared radiation in this case, and optical-based alignment, as is commonly used in chip bonding, is very difficult. Therefore, it is not easy to replace the semiconductor-based plates in the porous arrangement 305 with metal plates.

[0140] However, the manufacturing method according to the 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 aligned with sufficient precision. Figure 4 The method steps of the manufacturing method for the micro-optical unit 305 according to the present invention are illustrated schematically:

[0141] Figure 4 First, three plates 360.1, 360.2, and 360.3 for the micro-optical unit 305 are shown, which are not only conductive in the example shown, but also made of metal.

[0142] Figure 4 Figure b shows the arrangement of plates 360.1, 360.2, and 360.3 relative to each other. In this case, 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.

[0143] Figure 4 c now schematically illustrates the piercing of a stack of plates having plates 360.1, 360.2, and 360.3 by a drilling device 900. This is only... Figure 4 The diagram in c is schematic; the drilling direction is indicated by arrows. It is important now that, in principle, the entire stack of boards is pierced by the same drilling device 900 in a single attempt and during the same drilling process.

[0144] Figure 4Figure 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 centered on axis Z. Again, Figure 4 A series of holes 351.1, 351.2 and 351.3 are depicted purely as examples; however, naturally, multiple holes or sequences of holes exist in the porous plates 350.1, 350.2 and 350.3.

[0145] Furthermore, it is conceivable that the drilling device 900 pierces not only plates 360.1, 360.2, and 360.3, but also the insulating plate or layer. Whether this is possible depends solely on the drilling method used.

[0146] Figure 5 A flowchart illustrating a method for manufacturing a micro-optical unit 305 for a multi-particle beam system 1 according to the present invention is shown: firstly, in method step S1, a first plate 360.1 of a conductive micro-optical unit 305 is provided.

[0147] In method step S2, a conductive second plate 360.2 is provided for the micro-optical unit 305.

[0148] In method step S3, a plate stack is created: the creation of the 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.

[0149] Then, method step S4 performs the following operation: piercing the entire created plate stack, which has at least a first plate 360.1 and a second plate 360.2 of the micro-optical unit 305, thereby creating a first plurality of holes 351.1 in the first plate 360.1 of the micro-optical unit 305 and a second plurality of holes 351.2 in the second plate 360.2 of the micro-optical unit 305. As a result, the sequence of holes 350.1, 350.2 in the plates 360.1, 360.2 of the plate stack produced during the same drilling process has precise alignment, particularly in a process-inherent manner. Optionally, the plate stack may also include at least one additional plate, and thus include at least a third plate 360.3 of the micro-optical unit 305, which is conductive. In this case, the third plate 360.3 of the micro-optical unit 305 is fixed relative to and electrically insulated from the first plate 360.1 and the second plate 360.2 of the micro-optical unit 305. During step S4 of the method, the third plate of the micro-optical unit 305 is also punctured, thus creating 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 made of non-conductive but insulating materials (e.g., silicon dioxide) may also be provided.

[0150] In method step S4, the plate stack can be pierced in different ways: examples of drilling methods include, for example, laser drilling, micro EDM drilling, mechanical high-speed micro drilling, vibratory drilling, ultrasonic drilling, or using a focused ion beam (FIB). For details of these methods, refer to the explanations given in the overview section of this specification.

[0151] Optionally, the plate stack can be flushed, and in a further method step S5, 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 diameter S of the flushing hole can be related 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 as follows: S ≥ 10A, preferably S ≥ 100A.

[0152] exist Figure 13The flowchart illustrates a modified manufacturing method for the micro-optical unit 305 used in the multi-particle beam system 1: In this case, method steps S1 to S3 are first performed as described above. Before piercing the plate stack according to step S4, in the described exemplary embodiment, in step S11, 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 in step S12, the rinsing agent is cooled, thus solidifying it. For example, temperature control can be achieved by performing the method in a processing chamber, the internal temperature of which can be set, or the liquid can be supplied in a heated state and subsequently self-cooled. Then, the entire plate stack is pierced in step S4. By arranging / supplying the solidified rinsing agent, the forces acting on plates 306.1 and 306.2 during piercing can be better absorbed, distributed, and dissipated. This can help to better prevent bending of plates 306.1 and 306.2. In another method step S13, the rinsing agent is heated and thus liquefied. For example, the entire plate stack can be heated during this process, and the flushing agent is also heated while doing so. In another method step S14, the flushing agent, now in liquid form again, is removed from the intermediate space. The aforementioned flushing holes can be used for filling and removing the flushing agent.

[0153] Alternatively, the entire plate stack can be annealed in another method step. This may be necessary in the case of the magnetically permeable final porous plate 350.f to ensure its permeability, for example, for use as a magnetic multi-deflector in the multi-particle beam system 1 when combining the micro-optical unit 305 with the magnetic lens 308.

[0154] Figure 6 The method steps of the manufacturing method according to the present invention are illustrated schematically. Figure 6 In the exemplary embodiment shown, the plates 360 of the micro-optical units 305 are not conductive or not conductive everywhere. Their conductivity is provided only partially, specifically in the region around the unformed aperture 351:

[0155] Specifically, three plates 360 that are not conductive are initially provided for the micro-optical unit 305. The plates 360 may have an insulating material as the substrate material, such as ceramic. Coarse holes 361 can now be formed in these plates 360. The coarse holes 361 are larger than the holes 362 that are ultimately manufactured in the micro-optical unit 305.

[0156] The coarse aperture 362 is metallized in another method step (see [link]). Figure 6c). For example, the metallization of the coarse aperture 361 can be achieved by sputtering or by electroplating. In this process, conductive regions 363 are formed around or adjacent to the coarse aperture 362. These, in turn, have openings 363. Their diameter is smaller than the diameter of the final aperture 351 of the micro-optical unit 305.

[0157] In another step of the process, plates 360.1, 360.2, and 360.3 with metallized coarse holes 361 are fixed relative to each other and arranged in a manner that is 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, because the plate material of plates 360.1, 360.2, and 360.3, as ceramic, can already be sufficiently insulating. Openings 363.1, 363.2, and 363.3 are not perfectly aligned with each other. However, this is not necessary at this stage of the manufacturing process:

[0158] This is because, such as Figure 6 As shown in Figure e, the metallized coarse holes 361 or conductive regions 362.1, 362.2, and 362.3 are subsequently pierced. Figure 6 The drilling device 900 and its direction of movement in this respect are again schematically shown in Figure e.

[0159] As a result, Figure 6 As shown in 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 manner inherent to the process.

[0160] therefore, Figure 6 The manufacturing method described herein not only allows for the fabrication of monolithic porous plates 350.1, 350.2, and 350.3 that are themselves (fully) conductive; conversely, it also allows for the fabrication of annular electrodes according to the invention. In this case, the annular electrodes are formed by conductive regions 362.1, 362.2, and 362.3 in the illustrated example. The supply of lines to the individual annular electrodes must be achieved in another method step; this is more complex than in the case of the monolithic porous plate 350, but it is also achievable. For example, a metal printing process prior to the plate stack assembly is suitable for this purpose. For example, conductor tracks can also be applied by a combination of sputtering and electroplating.

[0161] Figure 7 The method steps of a method for manufacturing a micro-optical unit 305 according to the present invention are illustrated schematically. For example, having Figure 7 The stack of plates 360.1, 360.2, and 360.3 shown in Figure a can be combined as follows: Figure 4 It is manufactured as described in a and 4b. However, with combination Figure 4 The difference shown in c is different. Figure 7The piercing of the plate stack in section a is now different, especially regarding the drilling direction: this is because the plate stack is pierced at a certain angle. The resulting angled holes 351.1, 351.2, and 351.3 are also precisely flush with each other, as shown below. Figure 7 The dashed guide line in B is shown. However, in this case of angled piercing, holes 351.1, 351.2, and 351.3 are not perfectly circular, but slightly elliptical. The ellipticity depends on the inclination relative to the normal of the plate stack during piercing.

[0162] Figure 8 Aspects of the manufacturing method according to the invention are schematically illustrated, wherein a focused ion beam (FIB) is used to pierce 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, which are clamped in a frame. This is illustrated by reference numeral 380 indicating the frame area and reference numeral 381 indicating the film area.

[0163] The plate stack shown should function as a single lens, for example, after the entire plate stack has been punctured. Therefore, in Figure 8 Voltages U1, U2, and U3 are schematically shown. However, instead of a single plate 360 ​​with a total height H over the entire width of the plate, two films with a small thickness h are provided. In this case, the corresponding voltage is applied to the lower and upper films in each case. From an electro-optical point of view, there is no significant difference in the fact that cavities 382.1, 382.2, and 382.3 are provided 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 arranged between the respective associated film pairs in a known manner.

[0164] In the case of piercing the plate stack, a focused ion beam can now be used in the same drilling process, starting from the top, first piercing the topmost film 360.1, then piercing the next film 360.2, and so on. Again, to be precise, in principle, in the same method steps, or in a way 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 therefore the x and y positions of the hole 351 to be created are fixed. The fact that only each film portion of height h needs to be pierced can be taken into account that the focused ion beam has only a relatively small focusing depth and therefore can only pierce relatively thin layers. Therefore, as... Figure 8 The method shown, which involves piercing the entire plate stack, is particularly suitable for plate stacks with a small total height, such as a height of a few micrometers.

[0165] Figure 9The process shown represents a solution to a problem where the overall height of the plate stack is large and the focusing depth of the focused ion beam is limited: the overall stack with plates 360.1 to 360.6 is divided into four sub-stacks. Specifically, plates 360.2 and 360.3, and plates 360.4 and 360.5, respectively form independent stacks in the sense defined in claim 1. Now, in each case, the individual stacks or sub-stacks are pierced by means of the FIB or by means of the focused ion beam. In this case, according to Figure 9 The stack of plates b forms the stack in which the lens transition occurs. Here, the alignment of the holes created in plates 360.2 and 360.3 is particularly critical. The same applies to the lens transition between plates 360.4 and 360.5, as... Figure 9 As shown in c. In contrast, the transition within the same lens is less critical. Therefore, it is possible to puncture the sub-stacks individually ( Figure 9 b and 9c) and individual plates or membranes ( Figure 9 Following steps a and 9d), the sub-stacking is assembled without any significant performance loss in the micro-optical unit 305, and corresponding alignment is performed. This assembly of the sub-stacking is carried out by... Figure 9 The brackets in the text indicate that this leads to the micro-optical unit 305.

[0166] In principle, multiple holes in a plate stack can be generated continuously. However, at least some of the multiple holes in a plate can also be generated simultaneously. Figure 10 An example of this situation is shown in the image: Figure 10 A is shown as a Manhattan-type electrode as a drilling device 900. It includes multiple electrodes 902 arranged on a base element 901. In principle, the Manhattan-type electrode is therefore a multi-electrode. It can be used to simultaneously create multiple openings at different locations in the plate 360, which can be said to be batch-based. The result of the piercing process is... Figure 10 Figure b shows a porous plate 350 with multiple circular holes 351, the arrangement of which corresponds to the arrangement of electrodes 902.

[0167] Figure 10 The Manhattan-type electrode shown can be used, for example, in micro EDM. However, the principle can also be applied to other drilling methods.

[0168] Figure 11 A plurality of porous plates 350 of the micro-optical unit 305 are schematically shown. In this case, Figure 11 a shows a plurality of circular holes 351, each having the same diameter and arranged in a regular pattern. Figure 11b illustrates a porous plate 350 with a circular hole 351; however, the diameter of the hole varies within the porous plate or depends on the position of the hole within the respective plate 350. In the example shown, the diameter of the hole 351 exhibits a radial dependence on the distance from the center C in the porous plate 350.

[0169] Figure 11 c shows a porous plate 350 with elliptical holes 351. Their longitudinal axis l varies with respect to the center M and is precise in orientation and size.

[0170] Figure 11 All the perforated plates 350 shown are monolithic perforated plates 350, 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.

[0171] In principle, it is applicable that the shape of the holes 351 in the plates 360, 350 of the plate stack can be circular, elliptical, n-fold, or irregular. The holes themselves are preferably arranged by means of a grating, such as a hexagonal grating. However, they can also be arranged in, for example, square or rectangular gratings.

[0172] According to an exemplary embodiment, adjacent holes 351 in the plates of the plate stack have a distance B, which is suitable for the following: 70 μm ≤ B ≤ 400 μm, preferably 90 μm ≤ B ≤ 400 μm or 120 μm ≤ B ≤ 400 μm.

[0173] For example, the following 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.

[0174] According to an exemplary embodiment, the following can be applied to the plate distance D between adjacent plates 350, 360 in a plate stack: 1 μm ≤ D ≤ 100 μm, preferably 20 μm ≤ D ≤ 100 μm or 40 μm ≤ D ≤ 100 μm.

[0175] According to one embodiment of the 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 understood to be the height of the plate stack simultaneously pierced by the drilling device 900. Of course, the micro-optical unit 305 may have at least one second or at least one additional plate stack. It is possible that the second or additional plate stack of the micro-optical unit is also created using the method described according to the invention. However, it is also possible that the second or additional plate stack of the micro-optical unit 305 is created using other methods, such as planarization and / or photolithography. The second or additional plate stack can then be aligned relative to the first plate stack.

[0176] With a correspondingly large size of the micro-optical unit 305, for example, with an aperture diameter A ≥ 150 μm, a porous plate thickness C ≥ 250 μm, and a plate distance D between porous plates 350 ≥ 30 μm, a relatively large micro-optical unit 305 can be provided. During operation of the multi-particle beam system, a relatively large voltage U can be applied to the relatively large micro-optical unit 305, for example, U ≥ 250 V, preferably U ≥ 300 V and U ≥ 350 V. This is particularly advantageous in multi-particle beam systems that operate using a large number of individual particle beams 3, because the field dependence of imaging aberrations (e.g., field curvature or field astigmatism) in such systems is particularly large, especially in the edge regions of a multi-particle beam arrangement with a large grating.

[0177] Figure 12 An aspect of another manufacturing method for the micro-optical unit 305 is schematically illustrated. Contrary to the methods described above, instead of piercing together arrangements of different plates or different layers stacked on top of each other, a female mold 910 is provided, around which various layers are initially constructed. The female mold 910 is removed at the end of the process, thus the holes 911 defined by the female mold 910 are precisely aligned with each other in a process-inherent manner. Therefore, complex alignment problems are also avoided according to this example.

[0178] Specifically, such a mold can be provided in the first method step. For example, it can have a Manhattan-like structure that defines the later position of the hole 911. Furthermore, separate electrodes, such as ring electrodes or lines for supplying voltage to the electrodes, can be provided through this mold. This central mold, which at least defines the size of the subsequent hole 911, can be constructed in various ways. For example, it can be a photoresist, silicon dioxide, etched metal (LiDAR process), coated metal (for deposition purposes), etc. Figure 12In diagram a, the female mold 910 is schematically depicted as a central block. This central block is arranged on the substrate 390. For example, this could be a wafer made of silicon.

[0179] After providing this basic structure including the female 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.

[0180] Subsequently, another layer 393 is deposited on the conductive layer 392. In principle, this is the insulating layer 393. The latter can be insulating from the outset (e.g., by sputtering deposition of an insulator such as silicon dioxide), or the layer can be initially deposited by electroplating and then lose its original conductivity and become an insulator through heat treatment. In principle, the electrolytic process of the isolator is known from the prior art in another context.

[0181] The described process of depositing alternating 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... Figure 12 Figure b illustrates this schematically. The holes 911 formed during this process are precisely aligned with each other.

[0182] The technique of applying the insulator by electroplating in principle and only becoming insulator during heat treatment or baking has the following advantages: In principle, all layers 392 to 396 can be applied by electroplating. This is easier in process control and can be managed without any possible machine changes when different layers are applied. There are also fewer contaminant handling issues in the electroplating process compared to sputtering.

[0183] Figure 14 Particle optical imaging via symmetrical and asymmetrical magnetic lenses is schematically illustrated. Beam tilting formation is also schematically illustrated. Figure 14 Figure a illustrates imaging through a symmetrical magnetic lens 700. In principle, the magnetic lens 700 can be an objective lens, field lens, projection lens, or any other magnetic lens. In this respect, only the principle is illustrated here. The Y-axis plots the Z component Bz of the magnetic field induced by the lens 700. The object G 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 G to be imaged 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 the particle beam path of a parallel or field beam, imaged through focal point F in focal plane E. Additionally, the center beam is also plotted. Therefore, Figure 14a shows a very general imaging situation through the magnetic lens 700.

[0184] Now, the azimuth angular velocity components v of particle beams 3 and 9, which are moving parallel to the particle optical axis Z, azimuthal The beam path through the magnetic lens 700 is schematically plotted below. The azimuth angular velocity component v is shown before the charged particle beams 3 and 9 enter the magnetic lens 700 or its magnetic field B or Bz. azimuthal The value is zero. Charged particles or particle beams 3 and 9 begin to rotate upon entering the magnetic field B or Bz of the magnetic lens 70°, with an azimuth angular velocity component v. azimuthal It increases and reaches its maximum value at the center of the magnetic lens 700. Then, the azimuth angular velocity component v azimuthal The velocity decreases again, and the charged particles or charged particle beams 3 and 9 leave the magnetic lens 70° without an azimuth angular velocity component, i.e., v azimuthal = 0.

[0185] For the purpose of comparison, Figure 14 b now illustrates the particle beam path for the case where 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 traversed by the charged particle or electron is asymmetrical rather than symmetrical: an off-axis electron emitted from the object G in a manner parallel to the particle's optical axis begins without an azimuth angular velocity component. It then rotates within the magnetic lens 700 and, due to the asymmetry, leaves the magnetic field with an azimuth angular velocity component. Therefore, v applies azimuthal ≠ 0. This azimuth angular velocity component causes the electron beam to tilt, or generally causes the charged particle beam to tilt. Therefore, parallel beams no longer meet concentrically in the focal plane E. Therefore, Figure 14 The situation described in b is typical for 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.

[0186] The basic concept of some aspects of the present invention is that, from the perspective of the charged particle beam, the aforementioned beam tilt can not only be caused by an asymmetric magnetic field, but can also be compensated for: if charged particles or particle beams 3, 9 suddenly enter the magnetic field, this in principle corresponds to an asymmetric passage of the magnetic field through the magnetic lens 700. Therefore, appropriate techniques allow for the compensation of undesirable beam tilt in the particle beam path, or the targeted setting of beam tilt in the particle beam path.

[0187] Figure 15 An arrangement having a micro-optical unit 305 and magnetic lenses for realizing multiple deflectors is schematically shown. For example, Figure 15 The layout described in the text can be integrated into Figure 1 In the multi-beam particle microscope 1 shown, the magnetic lens corresponds to magnetic lens 308. Hereinafter, we will assume this as an example.

[0188] The micro-optical unit 305 includes a plurality of successively arranged porous plates 350.1, 350.2, and 350.3, each of which is successively passed through by a first individual charged particle beam 3. For example, the micro-optical unit 305 can be manufactured by means of the method according to the invention for manufacturing a micro-optical unit 305 for a multi-particle beam system 1. With respect to the first particle 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 μ of the material of the final porous plate... r Satisfying relation μ r ≥ 1000, especially μ r ≥ 10000 or μ r ≥ 15000. The final porous plate 350.f can be made of materials such as Permenorm. ® Or it could be another material. Regarding its central hole 351.c, the final porous plate 350.f is centered relative to the magnetic field lens 308.

[0189] To provide options for setting or correcting the azimuth tilt of the first individual charged particle beams 3a, 3b, 3c, it is now the case that during operation of the multi-particle beam system 1, the final porous plate 350.f of the micro-optical unit 305 is arranged within the magnetic field 701 generated by the magnetic field lens 308. The magnetic field 701 of the magnetic field lens 308, or the area where the magnetic field 701 of the magnetic lens 308 is present, is within... Figure 15 The area is schematically shown in a very simplified manner through the dashed lines.

[0190] Due to the final permeability of the porous plate of 350.f, Figure 15 In practice, the magnetic field 701 of the magnetic lens 308 experiences a sharp boundary, 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 particle beams 3a, 3b, and 3c is substantially proportional to the magnetic field strength and depends on the field height or the distance between the observed individual charged particle beam 3a and 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 the axial beam 3b on the particle optical axis Z does not experience any tilt.

[0191] The asymmetry of the magnetic field 701 is also through the principal geometric axis A of the field lens 308. xThe schematic diagram and two distances dFF and d1 are schematically shown: 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 selected during the operation of the multi-particle microscope 1 in such a way that, for example, the following relationship applies to the magnetic field Bz on axis Z at the magnetic field 701 or the final porous plate 350.f: 0.1 mT ≤ Bz ≤ 10.0 mT, and in particular 1.0 mT ≤ Bz ≤ 10.0 mT.

[0192] A portion of the controller 10 or 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 cause changes in the magnetic field strength passing through the magnetic field lens 308 to tilt the azimuth angle of the first individual charged particle beam 3a, 3b, 3c, or generally the first individual charged particle beam 3, when incident on the object 7 and / or when passing through the objective lens 102 of the multi-particle beam system 1.

[0193] Furthermore, in the example shown, the magnetic field strength of the magnetic field lens 308 is changed by a maximum of + / -50% of its nominal value for the purpose of setting the azimuth tilt of the first individual particle beam 3. In this case, the nominal value is defined as a value that corresponds to a fully corrected azimuth beam tilt, for example, at object 7 or at the surface of an object such as a wafer surface.

[0194] Figure 15 A specific example of a magnetic multi-deflector is shown. This example describes a specific arrangement of the magnetic multi-deflector in the particle beam path, namely, in the primary beam path or immediately downstream of the multi-beam generator 305 or the micro-optics unit 305, by means of which multiple first individual charged particle beams 3 are fully generated in the multi-particle beam system. However, in principle, an arrangement with the micro-optics unit 305 and magnetic lenses 700 at other locations in the particle beam path can be provided, specifically in both the primary and secondary beam paths. Therefore, the magnetic lens does not need to be the field lens 308; instead, it can be any desired magnetic lens 700.

[0195] Furthermore, in principle, it is possible that the charged particle beam does not suddenly enter the magnetic field 701 of the magnetic lens 700, but only suddenly leaves the magnetic field of the magnetic lens 700. The fundamental condition for setting the orientation tilt of a single charged particle beam lies solely in the asymmetry of the magnetic field through which the single charged particle beam passes. Therefore, instead of arranging the final porous plate of the micro-optical unit within the magnetic field of the magnetic lens, it is also possible to arrange the initial (i.e., first) porous plate of the micro-optical unit within the magnetic field of the magnetic lens arranged upstream thereon.

[0196] The exemplary embodiments described above should not be construed as limiting the present invention, but are merely for a better understanding of the invention. They can be combined with each other, in whole or in part, as long as this does not create a technical contradiction.

[0197] List of reference numerals

[0198] 1. Multi-beam particle system, multi-beam particle microscope

[0199] 3. Primary particle beam, first individual particle beam

[0200] 5 beams, incident position

[0201] 7. Objects, Samples, Wafers

[0202] 9th secondary particle beam, second separate particle beam

[0203] 10. Computer systems and controllers

[0204] 15 Sample surface, wafer surface

[0205] 25 Image points of the second individual particle beam

[0206] 81 multi-electrode

[0207] 82 ring electrode

[0208] 83 spacers

[0209] 84 ring electrode

[0210] 85 holes

[0211] 86 spacers

[0212] 99% Absorption Conductive Layer

[0213] 101 Object Plane

[0214] 102 Objective Lens

[0215] 103 field lens

[0216] 105 shaft

[0217] 108 intersection

[0218] 200 detector system

[0219] 205 Projection Lens System

[0220] 206 projection lens

[0221] 207 Multi-Particle Detector

[0222] 208 projection lens

[0223] 209 projection lens

[0224] 210 projection lens

[0225] 212 intersection

[0226] 214-hole filter, contrast diaphragm

[0227] 222 Collective Anti-Deflection System

[0228] 300-beam generator

[0229] 301 Particle Source

[0230] 303 Collimating Lens System

[0231] 304 porous array, filter plate

[0232] 305 micro-optical unit, porous arrangement, multi-beam particle generator

[0233] 306 perforated plate

[0234] 307 field lenses, aperture plates

[0235] 308 field lens

[0236] 309 particle beam

[0237] 310 perforated plate

[0238] 321 Intermediate Image Plane

[0239] 323-beam focal length

[0240] 333 holding area

[0241] 335 membrane region

[0242] 350-hole plate

[0243] 351 holes

[0244] 360 board

[0245] 361 coarse pores

[0246] 362 conductive area

[0247] Openings in the 363 conductive region

[0248] 370 spacer

[0249] 380 frame area

[0250] 381 membrane region

[0251] 382 chambers

[0252] 390 chip

[0253] 391 metal layer

[0254] 392nd floor

[0255] 393rd floor

[0256] 394th floor

[0257] 395th floor

[0258] 396th floor

[0259] 400 beam splitter, magnet device

[0260] 500 Scan Deflector

[0261] 600 displacement stage or positioning device

[0262] 700 Magnetic Lens

[0263] 701 Magnetic Field Strength

[0264] 900 Drilling Equipment

[0265] 901 substrate element

[0266] 902 Manhattan-type electrode

[0267] 910 negative mold, photoresist

[0268] A central axis

[0269] C. Lens center of the magnetic lens

[0270] E plane

[0271] F Focus

[0272] G object

[0273] Image B

[0274] The z-component of the Bz magnetic field

[0275] Z-axis

[0276] M Center

[0277] Height of the H-frame section

[0278] h Membrane height

[0279] x direction

[0280] y direction

[0281] z direction

[0282] l longitudinal axis

[0283] dFF is the final distance between the porous plate and the center of the magnetic lens.

[0284] d1 distance

Claims

1. A method for manufacturing a micro-optical unit for a multi-particle beam system, comprising the following steps: (a) A first plate of the micro-optical unit is provided, which is conductive; (b) A second plate of the micro-optical unit is provided, which is conductive; (c) Creating 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 are electrically insulated from each other; and (d) Puncture the entire created plate stack having at least the first plate and the second plate of the micro-optical unit, thereby creating 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 according to claim 1, in, The first plate and / or the second plate of the micro-optical unit are made of metal.

3. The method according to any one of the preceding claims, in, The plate stack also includes at least one additional plate and / or at least a third plate of the micro-optical unit, wherein the at least one additional plate and / or at least a third plate is conductive, and The third plate of the micro-optical unit is fixed relative to and electrically insulated from the first plate and the second plate of the micro-optical unit. During the execution of method step (d), the third plate of the micro-optical unit is also punctured, and thus a third plurality of holes are generated in the third plate of the micro-optical unit.

4. The method according to claim 3, wherein, The third plate of the micro-optical unit is metal.

5. The method according to claim 2 or 4, in, The first plate and / or the second plate and / or the third plate are magnetically conductive; and The following relationship applies to the relative permeability μ of the plate material. r μ r ≥ 1000, especially μ r ≥ 10000 or μ r ≥ 15000.

6. The method according to any one of the preceding claims, in, In step (d), the plate stack is pierced by laser drilling.

7. The method according to any one of claims 1 to 5, in, In step (d), the plate stack is punctured by micro EDM.

8. The method according to any one of claims 1 to 5, in, In step (d), the plate stack is pierced by high-speed mechanical micro-drilling.

9. The method according to any one of claims 1 to 5, in, In step (d), the plate stack is pierced by vibratory drilling or ultrasonic drilling.

10. The method according to any one of claims 1 to 5, in, In step (d), the plate stack is pierced using a focused ion beam (FIB).

11. The method according to any one of the preceding claims, in, At least one plate in the plate stack comprises an insulating material as a substrate material, particularly ceramic, and wherein the method further comprises the following steps performed prior to method steps (a) to (d): (e) A plurality of coarse holes are formed in the at least one plate having the insulating material as the substrate material; and (f) Metallize the coarse pores; In this process, the subsequent implementation of step (d) involves piercing the metallized coarse hole and thus forming multiple holes.

12. The method according to claim 11, in, The coarse pores are metallized by sputtering and / or by electroplating.

13. The method according to any one of the preceding claims, in, Multiple holes in the plates of the plate stack are generated simultaneously in method step (d).

14. The method according to any one of claims 1 to 12, in, Multiple holes in the plates of the plate stack are continuously generated in method step (d).

15. The method according to any one of the preceding claims, in, Each of the plurality of holes has a diameter A, wherein the following applies: 40 μm ≤ A ≤ 400 μm, especially 80 μm ≤ A ≤ 400 μm or 110 μm ≤ A ≤ 400 μm.

16. The method according to claim 15, in, The holes in the plates of the plate stack have circular, elliptical, n-fold, or irregular shapes.

17. The method according to any one of the preceding claims, in, Adjacent holes in the plates of the plate stack are spaced by a distance B, wherein the distance B applies as follows: 70 μm ≤ B ≤ 400 μm, especially 90 μm ≤ B ≤ 400 μm or 120 μm ≤ B ≤ 400 μm.

18. The method according to any one of the preceding claims, in, The following applies to the thickness C of the plates in the plate stack: 20 μm ≤ C ≤ 500 μm, especially 150 μm ≤ C ≤ 500 μm or 250 μm ≤ C ≤ 500 μm.

19. The method according to any one of the preceding claims, in, The following applies to the plate distance D between adjacent plates in the plate stack: 1 μm ≤ D ≤ 100 μm, especially 20 μm ≤ D ≤ 100 μm or 40 μm ≤ D ≤ 100 μm.

20. The method according to any one of the preceding claims, in, The following applies to the total height H of the plate stack: 50 μm ≤ H ≤ 1000 μm, especially 300 μm ≤ H ≤ 1000 μm or 500 μm ≤ H ≤ 1000 μm.

21. The method according to any one of the preceding claims further comprises the following steps: After puncturing according to step (d), the plate stack is flushed and the drilling material is removed through flushing holes in the first plate and the second plate of the micro-optical unit, wherein the diameter S of the flushing hole is subject to the following relationship with respect to the diameter A of the hole in the first plate and the second plate of the micro-optical unit: S ≥ 10A, in particular S ≥ 100A.

22. The method of claim 21, further comprising the step of: Before puncture according to step (d) - Fill the intermediate 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 piercing according to step (d) - Heating the flushing agent to liquefy it; and - Remove the flushing agent from the intermediate space.

23. The method of claim 5, further comprising the following step: After piercing according to step (d) - Anneal the plate stack.

24. The method according to any one of the preceding claims, wherein, The micro-optical unit includes at least a second plate stack or another plate stack.

25. The method according to claim 24, in, The second plate stack or additional plate stack of the micro-optical unit is created by method steps (a) to (d); or The second plate stack or other plate stack of the micro-optical unit is created by means of planar processing and / or photolithography.

26. The method according to claim 25, wherein, The method further includes the following method steps: (g) Align 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 of any one of the preceding claims.

28. A micro-optical unit for a multi-particle beam system, in, The micro-optical unit includes a first porous plate made of metal and a second porous plate made of metal. In each case, the following applies to the pore diameter A of the first porous plate and the second porous plate: A ≥ 150 μm, In each case, the following applies to the thickness C of the first porous plate and the second porous plate: C ≥ 250 μm; and The following applies to the plate distance 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 a micro-optical unit as described in any one of claims 27 and 28.

30. The multi-particle beam system according to claim 29, in, During operation of the multi-particle beam system, a voltage U of U ≥ 250V, particularly U ≥ 300V or U ≥ 350V, can be applied to the first porous plate and / or the second porous plate.

31. The multi-particle beam system according to any one of claims 27 to 30, It also includes a magnetic lens, which is positioned downstream of the micro-optical unit relative to the particle beam path of the multi-particle beam system during operation of the multi-particle beam system. in, The micro-optical unit has a magnetically perforated final porous plate relative to the particle beam path of the multi-particle beam system, wherein the following relationship applies to the relative permeability μ of the material of the final porous plate. r μ r ≥ 1000, especially μ r ≥ 10000 or μ r ≥ 15000; and During operation of the multi-particle beam system, the final porous plate of the micro-optical unit is arranged within a magnetic field generated by the magnetic lens.

32. The multi-particle beam system according to claim 31, It also includes the controller, in, The controller is configured to control the magnetic lens and set its magnetic field strength. The controller is further configured to tilt the azimuth angle of individual particle beams passing through the magnetic lens during operation by changing the magnetic field strength of the magnetic lens.

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

34. A multi-particle beam system, comprising: Particle source, used to generate beams of charged particles; A multi-beam generator, through which the charged particle beam passes to form a plurality of first individual charged particle beams, the plurality of first individual charged particle beams forming a first field; The first particle optical unit has a first particle beam path and is configured to image the generated first individual particle beam onto the object plane, such that the first individual particle beam strikes the object at the incident position where the second field is formed. Objective lens, particularly a magnetic objective lens, through which the first individual particle beam passes; and Controller; The multi-beam generator includes a micro-optical unit having a plurality of successively arranged porous plates. In each case, the first individual charged particle beam passes successively through the porous plates. The micro-optical unit includes a magnetically permeable final porous plate relative to the particle beam path. The following relationship applies to the relative permeability μ of the material of the final porous plate. r μ r ≥ 1000, especially μ r ≥ 10000 or μ r ≥ 15000, The first particle optical unit includes a magnetic field lens. During operation of the multi-particle beam system, the final porous plate of the micro-optical unit is arranged within the magnetic field generated 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 such that the orientation tilt of the first individual charged particle beam when it impacts the object and / or passes through the objective lens is set by the change in the magnetic field strength of the magnetic field lens.

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

36. The multi-particle beam system according to any one of claims 34 to 35, in, The z-component Bz of the magnetic field B on the particle's optical axis z takes a value at the final porous plate, and the following relationship applies to this value: 0.1mT ≤ Bz ≤ 10.0mT, and in particular 1.0mT ≤ Bz ≤ 10.0mT.

37. The multi-particle beam system according to any one of claims 34 to 36, in, The magnetic field strength Bz of the magnetic field lens is changed by a maximum of ±50% of its nominal value for the purpose of setting the azimuth tilt of the first individual particle beam.

38. The multi-particle beam system according to any one of claims 34 to 37, in, The material of the final porous plate is Permenorm®.

39. The multi-particle beam system according to any one of claims 34 to 38, in, The multi-particle beam system is a multi-beam particle microscope.

40. The multi-particle beam system according to any one of claims 34 to 39, Also includes the following: A detection system having multiple detection areas that form a third field; The second particle optical unit, having a second particle beam path, is configured to image a second single charged particle beam emitted from an incident position in the second field onto a third field of the detection region of the detection system. and A beam splitter is arranged in the first particle beam path between the multi-particle source and the objective lens, and in the second particle beam path between the objective lens and the detection system; Both the first and second individual particle beams pass through the objective lens.

41. The multi-particle beam system according to claim 40, in, A second micro-optical unit having a plurality of continuously arranged porous plates is disposed in the second particle beam path, wherein the second individual charged particle beam passes continuously through the plurality of continuously arranged porous plates in each case, wherein, relative to the particle beam path, the micro-optical unit comprises a magnetically permeable final porous plate, wherein the following relationship applies to the relative permeability μ of the material of the final porous plate. r μ r ≥ 1000, especially μ r ≥ 10000 or μ r ≥ 15000, The second particle optical unit includes a magnetic projection lens. During operation of the multi-particle beam system, the final porous plate of the second micro-optical unit is arranged within the magnetic field generated by the magnetic projection lens. The controller is configured to control the magnetic projection lens and set its magnetic field strength. The controller is further configured such that the azimuth angle of the second individual charged particle beam when it impacts the detection area and / or when it passes through a contrast aperture arranged flush with the intersection point of the second individual particle beam is set by a change in the magnetic field strength of the magnetic projection lens.

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