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

Abstract

The invention relates to a method for producing a micro-optical unit for a multiple particle beam system, comprising the following steps: (a) providing a first plate of the micro-optical unit that is electrically conductive; (b) providing a second plate of the micro-optical unit that is electrically conductive; (c) creating a plate stack comprising stacks of the first plate of the micro-optical unit and the second plate of the micro-optical unit one above the other, wherein the first plate of the micro-optical unit and the second plate of the micro-optical unit are fixed relative to one another in the plate stack and are electrically insulated from one another; and (d) drilling through the entire created plate stack comprising at least the first plate and the second plate of the micro-optical unit, and thereby creating both a first number of apertures in the first plate of the micro-optical unit and a second number of apertures in the second plate of the micro-optical unit.

Description

[0001] Method for producing a micro-optics for a multi-particle beam system, micro-optics and multi-particle beam system

[0002] Field of the invention

[0003] The invention relates generally to multi-beam particle systems and, more particularly, to multi-beam particle microscopes that operate with a plurality of charged single-particle beams. Specifically, the invention relates to a method for manufacturing micro-optics for a multi-beam particle system, to micro-optics, and to a multi-beam particle system.

[0004] State of the art

[0005] With the continuous development of ever smaller and more complex microstructures such as semiconductor devices, there is a need for the further development and optimization of planar manufacturing techniques and inspection systems for the production and inspection of small dimensions of microstructures. For example, the development and manufacture of semiconductor devices requires verification of the design of test wafers, and planar manufacturing techniques require process optimization for reliable, high-throughput manufacturing. Furthermore, there is a recent demand for semiconductor wafer analysis for reverse engineering and customized, individual configuration of semiconductor devices. Therefore, there is a need for inspection tools that can be used at high throughput to examine microstructures on wafers with high accuracy.

[0006] Typical silicon wafers used in the manufacture of semiconductor devices have diameters of up to 300 mm. Each wafer is divided into 30 to 60 repeating regions (“dies”) with a size of up to 800 mm. 2A semiconductor device comprises multiple semiconductor structures fabricated in layers on a wafer surface using planar integration techniques. Due to the manufacturing processes, semiconductor wafers typically have a flat surface. The feature size of the integrated semiconductor structures ranges from a few pm to critical dimensions (CD) of a few nanometers, with feature sizes becoming even smaller in the near future; it is expected that feature sizes or critical dimensions (CD) will correspond to the 3 nm, 2 nm, or even smaller technology nodes of the International Technology Roadmap for Semiconductors (ITRS) in the future. With the small feature sizes mentioned above, defects the size of the critical dimensions must be identified quickly and over a very large area.For several applications, the specification requirement for the accuracy of a measurement provided by an inspection device is even higher, for example, by a factor of two or an order of magnitude. For example, a semiconductor feature width must be measured with an accuracy of less than 1 nm, such as 0.3 nm or even less, and a relative position of semiconductor structures must be determined with an overlay accuracy of less than 1 nm, such as 0.3 nm or even less.

[0007] A recent development in the field of charged particle microscopes (CPM) is the MSEM, a multi-beam scanning electron microscope. A multi-beam scanning electron microscope is disclosed, for example, in US Pat. No. 7,244,949 B2 and US Pat. No. 2019 / 0355544 A1. In a multi-beam electron microscope, or MSEM, a sample is simultaneously irradiated with a plurality of individual electron beams arranged in a field or grid. For example, 4 to 10,000 individual electron beams can be provided as primary radiation, with each individual electron beam separated from a neighboring individual electron beam by a distance of 1 to 200 micrometers. For example, an MSEM has approximately 100 separate individual electron beams (“beamlets”) arranged, for example, in a hexagonal grid, with the individual electron beams separated by a distance of approximately 10 pm.The plurality of charged single-particle beams (primary beams) are focused by a common objective lens onto the surface of a sample under investigation. The sample can be, for example, a semiconductor wafer attached to a wafer holder mounted on a movable stage. During illumination of the wafer surface with the charged primary single-particle beams, interaction products, such as secondary electrons or backscattered electrons, emanate from the wafer surface. Their starting points correspond to the locations on the sample on which the plurality of primary single-particle beams are focused. The quantity and energy of the interaction products depend on the material composition and the topography of the wafer surface.The interaction products form multiple secondary single-particle beams (secondary beams), which are collected by the common objective lens and projected by a projection imaging system of the multi-beam inspection system onto a detector arranged in a detection plane. The detector comprises multiple detection regions, each of which contains multiple detection pixels, and the detector records an intensity distribution for each of the secondary single-particle beams. This results in an image field of, for example, 100 pm x 100 pm.

[0008] The prior art multi-beam electron microscope comprises a sequence of electrostatic and magnetic elements. At least some of the electrostatic and magnetic elements are adjustable to adjust the focus position and stigma of the plurality of charged single-particle beams. The prior art multi-beam charged particle system further comprises at least one crossover plane of the primary or secondary charged single-particle beams. Furthermore, the prior art system comprises detection systems to facilitate adjustment. The prior art multi-beam particle microscope comprises at least one beam deflector (deflection scanner) for collectively scanning a region of the sample surface using the plurality of primary single-particle beams to obtain an image field of the sample surface.

[0009] To separate the particle-optical beam path of the primary beams from the particle-optical beam path of the secondary beams, a so-called beam splitter (also known as a "beam separator" or "beam divider") is used. Separation is achieved using special arrangements of magnetic and / or electrostatic fields, for example, a Wien filter.

[0010] In multi-column particle beam systems, a fundamental distinction is made between systems that operate with a single column and systems that operate with multiple columns. In systems with a single column, the individual particle beams pass at least partially through the same particle optics or through one or more global particle lenses. Furthermore, in a single column, the individual particle beams are relatively close to one another. Despite the partially global particle optical elements, even with single columns there is a need for the individual particle beams to be individually influenced and / or shaped in order to correct imaging errors such as field curvature, field astigmatism, and other aberrations. So-called micro-optics can be used for this individual influence and / or shaping of the individual particle beams.Micro-optics is often also referred to as a multi-beam particle generator for generating and shaping a large number of individual particle beams. The multi-beam particle generator or micro-optics comprises a sequence of several multi-aperture plates that can be used for active beam shaping or at least one of which can be used for active beam shaping. For this purpose, electrodes that can be controlled collectively or individually can be provided in the area of ​​the apertures. These can be ring electrodes or multipole electrodes, for example. According to another example, a multi-aperture plate can be monolithic, with a voltage applied across the multi-aperture plate as a whole, i.e. the monolithic multi-aperture plate is then at a specific potential, so that its openings, in conjunction with other particle-optical elements, can create a lens effect.Other designs of a multi-aperture plate for active beam shaping are also possible.

[0011] For the best possible single-particle beam shaping / influencing, it is necessary that the apertures through which a single-particle beam passes are precisely aligned. For example, it may be necessary for the centers of the apertures to be exactly aligned. Furthermore, the apertures in known multi-aperture plates are relatively small, e.g., aperture diameters are each less than 100 μm, e.g., only 90 μm or less. These two conditions—small aperture diameters and precise alignment of the apertures / electrodes, including control—can be met by using MEMS techniques to manufacture micro-optics. In other words, similar processes are used to manufacture micro-optics and their multi-aperture plates that can also be used in semiconductor production.

[0012] The applications of semiconductor components open up, for example, through the combination of regions with different doping levels or through the influence of insulating separation layers. To meet these requirements, during the production of semiconductor components, various layers are deposited sequentially on a base substrate in the form of a disc, the so-called wafer (so-called planar technology). Silicon, for example, is used as the base substrate, and silicon oxide, for example, is used as the insulating layer. The deposited layers can then be structured using lithographic processes. This allows the production of integrated circuits with conductor tracks, i.e., semiconductor chips, or even micro-optics with multi-aperture plates for multi-particle beam systems.

[0013] As precise as the production of micro-optics using MEMS technologies is, there are still disadvantages to this type of manufacturing: The development time for producing a micro-optic device is relatively long, often between six months and nine months. Changes to the manufacturing process are difficult or only possible with considerable time expenditure. Furthermore, there are only a few semiconductor manufacturers, process control in semiconductor manufacturing is challenging, and very expensive equipment is required for semiconductor manufacturing. Description of the invention

[0014] It is therefore an object of the invention to provide an improved method for producing micro-optics for a multi-particle beam system. The method should be faster than known methods, without compromising the quality of the micro-optics or impairing the achievable resolution in multi-particle beam systems. Furthermore, the method should be simple and cost-effective to implement.

[0015] This object is achieved by the subject matter of the independent patent claims. Advantageous embodiments of the invention are set forth in the dependent patent claims.

[0016] The present patent application claims priority from German patent application No. 10 2023 133 567.7 of November 30, 2023, the disclosure of which is incorporated in its entirety by reference into the present patent application.

[0017] The present invention is essentially based on two fundamental findings:

[0018] (1 ) It has been shown that the silicon material used for micro-optics can pose serious problems: For example, undesirable surface potentials can occur, and the conductivity of the silicon can change over time. Both of these factors have an undesirable influence on the charged single-particle beams passing through the micro-optics, thus affecting the beam quality and, in turn, the resolution achievable with a multi-particle beam system during operation.

[0019] (2) Furthermore, it has surprisingly been found that the desire / trend towards further miniaturization of micro-optics for the purpose of improving resolution is not always correct or always necessary. Instead, there can be real advantages in manufacturing micro-optics with somewhat larger dimensions, such as larger apertures and / or thicker multi-aperture plates. Advantages are offered in particular by reduced parasitic effects such as reduced beam deflections with a comparable desired electron-optical effect and by higher voltages that can be applied to the multi-aperture plates of the micro-optics. The latter is of particular interest in micro-optics for ever-increasing numbers of single-particle beams and ever-larger image fields. It is therefore a fundamental idea of ​​the invention to use other manufacturing processes instead of MEMS techniques, namely those that can be used in metal processing.The fact that such metal processing processes tend to be used only to create somewhat larger structures is not necessarily a disadvantage. Instead, metal processing processes offer the advantage that silicon is no longer a mandatory material. In particular, the method according to the invention also makes it possible to produce micro-optics that have one or more multi-aperture plates made of metal. Furthermore, with skillful process management, the problem of precisely aligning the multi-aperture plates to one another can be solved, regardless of their material or light-optical or IR transparency; the multi-aperture plates are then correctly aligned to one another automatically or inherently within the process.

[0020] According to a first aspect of the invention, the invention relates to a method for manufacturing a micro-optic system for a multi-particle beam system, comprising the following steps:

[0021] (a) providing a first plate of the micro-optics which is electrically conductive;

[0022] (b) providing a second plate of the micro-optics which is electrically conductive;

[0023] (c) producing a plate stack comprising stacking the first plate of the micro-optics and the second plate of the micro-optics on top of each other, wherein the first plate of the micro-optics and the second plate of the micro-optics are fixed relative to each other in the plate stack and are electrically insulated from each other; and

[0024] (d) drilling through the entire produced plate stack with at least the first plate and the second plate of the micro-optics and thereby producing both a first plurality of apertures in the first plate of the micro-optics and a second plurality of apertures in the second plate of the micro-optics.

[0025] As stated in the introductory description, the term "micro-optics" refers to a sequence of multiple multi-aperture plates, of which at least one multi-aperture plate is used during operation for actively shaping the plurality of single-particle beams in the multi-particle beam system. Preferably, each of the apertures is penetrated by exactly one single-particle beam.

[0026] Patent claim 1 does not initially refer to a multi-aperture plate, but rather to a first micro-optic plate and a second micro-optic plate, respectively. This is due to the fact that the apertures in the first and second plates are only formed during the manufacturing process. The first micro-optic plate is electrically conductive. The entire first micro-optic plate can be electrically conductive, or only parts of the first plate can be. The same applies to the second micro-optic plate. The property of electrical conductivity contributes to, or is even necessary for, the use of many processes known from metal processing for manufacturing micro-optics for a multi-particle beam system. This will be discussed in more detail later.

[0027] Creating the plate stack comprises stacking the first micro-optic plate and the second micro-optic plate on top of each other, wherein the first micro-optic plate and the second micro-optic plate are fixed relative to each other in the plate stack and are electrically insulated from each other. The fixing and electrical insulation can be achieved simultaneously and / or using the same means; however, it is also possible to use different means for fixing and electrical insulation. For example, it is possible to use electrically insulating spacers or to provide a complete electrically insulating plate.

[0028] The plate stack comprises at least a first micro-optic plate and a second micro-optic plate. However, the plate stack can also comprise further micro-optic plates. In process step (d), the entire produced plate stack is drilled through with at least the first and second micro-optic plates, thereby creating both a first plurality of apertures in the first micro-optic plate and a second plurality of apertures in the second micro-optic plate. Apertures that are to be penetrated by the same individual particle beam during operation of the micro-optic plate or the multi-particle beam system are thus created in the same process step or during the same drilling process.If the drilling is carried out with appropriate precision using a drilling means, the apertures assigned to one another in the first plate of the micro-optics and the second plate of the micro-optics and, if applicable, one or more further plates of the micro-optics are automatically correctly aligned with one another.

[0029] According to a preferred embodiment of the invention, the first plate of the micro-optics and / or the second plate of the micro-optics is metallic. For example, the metal can be copper, silver, iron, aluminum, tungsten, gold, brass, platinum, stainless steel, or another metal or metal alloy, or combinations of the aforementioned materials. The metal plate itself can also have a surface finish, such as gold plating. Alternatively, it is also possible for the first plate of the micro-optics and / or the second plate of the micro-optics to be made of a semiconductor material. This semiconductor material can, for example, comprise silicon.

[0030] According to a further preferred embodiment of the invention, the plate stack further comprises at least one further and thus at least a third plate of the micro-optics, which is electrically conductive. The third plate of the micro-optics is fixed relative to the first plate of the micro-optics and the second plate of the micro-optics and is electrically insulated from each of them. When carrying out method step (d), the third plate of the micro-optics is also drilled through, thereby creating a third plurality of apertures in the third plate of the micro-optics. This third plurality of apertures is therefore also correctly aligned with the remaining apertures of the first plate and the second plate due to the process.

[0031] According to a preferred embodiment of the invention, the third plate of the micro-optics consists of a metal. The same applies to any additional plates that may be present. It is fundamentally possible for all plates of the micro-optics to be made of the same material, and in particular, the same metal; however, this is not necessarily the case.

[0032] According to a preferred embodiment of the invention, the first plate and / or the second plate and / or the third plate and / or a further plate of the micro-optics is magnetically conductive. In addition, a permeability p r of the material of the plate (respectively) the following relation: p r > 1000, preferably p r > 10000 or p r > 15000.

[0033] Magnetic conductivity of one, several, or even all plates enables expanded application areas and possible uses of a micro-optic system. A plate or a sequence of plates of the micro-optic system serves, for example, to adjust a focus. Magnetically conductive plates, and in particular a multi-aperture plate that is the final one with respect to the particle-optical beam path during operation of the micro-optic system, can also fulfill the function of a multi-deflector in combination with a magnetic lens arranged shortly thereafter: For such an application, the final multi-aperture plate is arranged within the magnetic field of the subsequent magnetic lens or can be arranged there. A specific design of such a multi-deflector will be discussed in more detail later in this patent application.There are various magnetically conductive materials with a permeability p in the state of the art. r > 1000. These include, among others, soft magnetic standard materials such as pure iron (e.g. Vacofer®), nickel-iron alloys with an approximately 75% nickel content such as Mu-metal, Permalloy or Supermalloy, nickel-iron alloys with an approximately 50% nickel content such as Permenorm®, cobalt-iron alloys with an approximately 50% cobalt content such as Vacoflux®, or silicon-iron alloys with an approximately 3% silicon content such as Trafoperm®. These materials are also commercially available as thin membranes, for example with a thickness of 25 pm, 50 pm, 100 pm or 250 pm. Due to their low thickness, plates made of such materials are fundamentally suitable for the inventive method for producing a micro-optic system for a multi-particle beam system.

[0034] According to a preferred embodiment of the invention, the plate stack is drilled through in step (d) using laser drilling. Laser drilling is a non-cutting thermal cutting process. There are various types of laser drilling processes, such as single-pulse drilling, percussion drilling, trepanning, and helical drilling. Single-pulse drilling is the fastest; it "shoots" through the material using a single pulse. In percussion drilling, several pulses are applied to the same point to laser a hole through the material. Trepanning occurs when, after the through-hole has been drilled, the hole is cut out by following the hole contour. Helical drilling may require special optics. In general, the precision of the drilling and the smoothness of the hole walls depend on the material being drilled and the type of laser radiation.Copper, for example, absorbs green and blue radiation very well, but not common infrared very well. Laser drilling processes are now very fast and also very efficient: For example, it is possible to drill 200 holes per second into 1 mm thick titanium sheet using single-pulse micro-drilling. The focus diameter of the laser used is, for example, 12 pm, and the resulting hole has a diameter of just under 80 pm. An aperture diameter of 80 pm already corresponds to the dimensions used in the state of the art for apertures when these are created using MEMS technologies. Using laser drilling, therefore, it is possible to produce both very small apertures, if desired, and much larger apertures, if necessary using other laser drilling technologies. Furthermore, the processes are very fast. Furthermore, laser drilling as a manufacturing process offers the advantage that the material to be drilled does not necessarily have to be a metal or even have to be conductive.Insulators can also be drilled through using laser drilling. Therefore, laser drilling can also drill through stacks of plates containing a sequence of electrically conductive and electrically insulating plates at once, using the same laser pulse, or using the same number of laser pulses.

[0035] According to a further preferred embodiment of the invention, the drilling of the plate stack in step (d) is carried out using micro-EDM. Micro-EDM, or micro-spark erosion, is a form of EDM (Electrical Discharge Machining) and can be described as a combination of drilling and sinking erosion techniques. This technique, which is based on spark erosion as a machining method, is highly suitable for shaping electrically conductive materials of various hardnesses into the correct shape at high speed and precision.

[0036] EDM is a non-contact process that allows the removal of material over very short lengths without creating mechanical stress in the material. The material is formed by highly localized melting and evaporation as a result of electrical discharges between an electrode and the material being processed. The discharges, which form tiny plasma channels with temperatures of up to 10,000°C, melt very small amounts of the material locally. When the current flow is interrupted, the generated plasma collapses, and the resulting vacuum draws the molten material out into the surrounding dielectric medium. For discharges to occur, the material must have sufficient electrical conductivity, while material hardness is not important. Therefore, in principle, all metals and many semiconductors are suitable for EDM and also for micro-EDM.

[0037] Micro-EDM is a special form of EDM that allows workpieces to have features as small as approximately 10 pm. These small features are achieved using electrodes that are also very small. Thus, even with micro-EDM, apertures of the order of magnitude already used for micro-optics can easily be achieved. Furthermore, the micro-EDM process is significantly faster than planar integration techniques.

[0038] According to a preferred embodiment of the invention, the plate stack is drilled through in step (d) using mechanical high-speed micro-drilling. Solid carbide micro-drills, for example, can be used for this purpose. In this way, drill hole diameters of just a few millimeters can be realized, as well as drill hole diameters of just 30 μm or even just 10 μm.

[0039] According to a preferred embodiment of the invention, the drilling of the plate stack in step (d) is carried out by means of vibration drilling or ultrasonic drilling. The principle of vibration drilling is to generate axial vibrations or oscillations in addition to the feed movement of the drill, so that the drill chips break up and can then be easily removed from the cutting zone. A distinction is made between self-sustaining vibration systems and forced vibration systems. In vibration drilling with natural vibration, the natural frequency of the tool is used to cause it to vibrate naturally during cutting. The vibrations can be maintained by a mass-spring system in the tool holder itself. Another possibility is the use of a piezoelectric system to generate and control vibrations.These systems enable high vibration frequencies (up to 2 kHz) with small dimensions (a few pm) and are particularly suitable for drilling small holes.

[0040] Ultrasonic drilling uses vibrations in the ultrasonic range to create a drilled hole. It is a non-rotary material machining process. It is particularly suitable for hard and brittle materials. Ultrasonic waves generated in an ultrasonic transducer cause the drilling tool to vibrate in the feed direction, also inducing vibrations in the grains of an abrasive suspension. During a short fraction of the oscillation period, the workpiece is removed in micro-divisions. It is also possible to supplement conventional drilling with the additional use of ultrasound to improve working parameters.

[0041] According to a preferred embodiment of the invention, the drilling of the plate stack in step (d) takes place using a focused ion beam (FIB). When high-energy ions hit a sample, they sputter atoms out of the surface. Due to the sputtering capability, a focused ion beam can be used as a tool for micro- and nanomachining, and materials in the micro- and nanoscale can be modified or processed. Gallium ions, for example, are used as focused ions, but other ions can also be used. Using focused ion beams, even features in the range of 10 to 15 nm can be milled, and the milling of features in the micrometer range is fully and comprehensively possible. The only problem with the use of a focused ion beam is its relatively shallow depth of field. This can therefore be difficult to process thick plates orto drill through thick plate stacks at once. However, there are solutions for this case as well, such as dividing a plate stack into several sub-stacks and then drilling through each of the sub-stacks using the FIB, especially at lens transitions where precise alignment of the apertures of different plates is very critical. The sub-stacks can then be combined to form a single stack.

[0042] In the drilling methods described above, the material removed by drilling must be removed from the plate stack. According to a preferred embodiment of the invention, flushing holes can therefore be provided in the plates of the plate stack, which have a larger diameter than the apertures in the first plate of the micro-optics and in the second plate of the micro-optics. These flushing holes can be created using the same or different methods as the apertures in the first plate of the micro-optics and in the second plate of the micro-optics; the method itself is not critical here. Instead, it is important that the diameter of the flushing holes is selected such that, during a flushing process in a process chamber after drilling through the plate stack, the removed material can be removed or flushed out through these flushing holes by means of a flushing process.A liquid, for example, can be used as a flushing agent, particularly in a metal drilling process. However, it is also possible to use a gas as a flushing agent, for example, after drilling through a metal using a laser or a focused ion beam.

[0043] Flushing holes also make it possible to remove or flush out any auxiliary materials used during the production of the plate stack / micro-optics. For example, it is possible to introduce a liquid between the plates of the plate stack before a mechanical drilling process, then cool it until it solidifies, and then drill through the plate stack. This allows the forces acting during drilling to be absorbed by the solidified liquid. After drilling, the plate stack can be reheated, the solidified liquid / solid is liquefied again, and can then be flushed out through the flushing holes.

[0044] According to a preferred embodiment of the invention, the method further comprises the following step: After drilling according to step d), rinsing the plate stack and removing drilling material through rinsing holes in the first plate of the micro-optics and in the second plate of the micro-optics, wherein the following relation applies to a diameter S of the rinsing holes in relation to the diameter A of the apertures in the first plate of the micro-optics and in the second plate of the micro-optics: S > 10A, preferably S > 100A.

[0045] According to a further preferred embodiment of the invention, the method further comprises the following steps: before drilling according to step d)

[0046] Filling a space between the first plate of the micro-optics and the second plate of the micro-optics with a liquid detergent, and

[0047] Cooling the detergent and thereby solidifying the detergent; and after drilling according to step d)

[0048] Heating the detergent and thereby liquefying the detergent; and

[0049] Removing the detergent from the gap.

[0050] The flushing holes described above can be used to fill and remove the detergent.

[0051] According to a further preferred embodiment of the invention, the method further comprises the following step: after drilling according to step d)

[0052] Annealing the plate stack.

[0053] Annealing the plate stack serves to restore the soft magnetic properties, or rather the high magnetic conductivity, of a magnetic plate. Stresses or vibrations that can occur during the inventive method for producing a micro-optic system for a multi-particle beam system could otherwise reduce the magnetic conductivity to such an extent that desired effects such as multi-deflection of individual particle beams can no longer be achieved using the plate. If a plate stack is annealed at a high temperature, further care must be taken to ensure that the electrical insulation between individual plates in the plate stack can also withstand the high temperatures of the annealing process. This can generally be ensured by selecting the appropriate material for the insulators.

[0054] According to a further preferred embodiment of the invention, at least one of the plates of the plate stack comprises an insulating material as base material, in particular a ceramic as base material, and the method further comprises the following steps, which are carried out before method steps (a) to (d):

[0055] (e) creating a plurality of coarse apertures in the at least one plate with the insulating material as the base material; and

[0056] (f) metallizing the coarse apertures; wherein, during subsequent execution of process step (d), the metallized coarse apertures are drilled through and thus the plurality of apertures are formed.

[0057] In this embodiment, not the entire plate of the plate stack is conductive, but only a portion of it, namely the areas metallized around the coarse apertures. This is sufficient to enable all material processing methods that require the conductivity of the material to be drilled. The diameter of the coarse apertures is naturally larger than the diameter of the apertures of the finished multi-aperture plates. The metallized coarse apertures, on the other hand, are smaller in diameter than the finished aperture diameters in the multi-aperture plate.

[0058] According to a preferred embodiment of the invention, the metallization of the coarse apertures is carried out by sputtering and / or by electroplating.

[0059] According to a preferred embodiment of the invention, in process step (d), the plurality of apertures in the plates of the plate stack are created simultaneously. For this purpose, a plurality of drilling means can be used simultaneously. These can be, for example, multiple laser pulses in laser drilling or a plurality of fixedly oriented electrodes (so-called "Manhattan electrodes") in the micro-EDM process. This type of simultaneous creation of drill holes is very fast.

[0060] According to an alternative embodiment of the invention, in process step (d), the plurality of apertures in the plates of the plate stack are successively created. Thus, the entire plate stack is first completely drilled through at a first location, then completely drilled through at a second location, and so on. In this embodiment, the drilling process used is relatively simple.

[0061] According to a preferred embodiment of the invention, the plurality of apertures each have a diameter A, where: 40 pm < A < 400 pm, preferably 80 pm < A < 400 pm or 1 10 pm < A < 400 pm. In the case of circular apertures, the diameter naturally corresponds to twice the radius. In the case of differently shaped apertures, for example elliptical apertures, the diameter A is defined as the smallest possible distance between the hole walls. In the case of ellipses, this then corresponds to twice the minor semi-axis. In the case of stepped apertures, which can be produced, for example, by means of stepped electrodes or by means of several drilling steps (e.g. first drilling through a plate with a small drilling medium, then partially drilling out with a larger drilling medium), the diameter A refers to the minimum diameter.

[0062] According to a preferred embodiment of the invention, the shape of the apertures in the plates of the plate stack is round, elliptical, n-fold, or irregular. The method according to the invention is therefore very flexible. According to a preferred embodiment of the invention, the centers of adjacent apertures in the plates of the plate stack have a distance B for which the following applies: 70 pm < B < 400 pm, preferably 90 pm < B < 400 pm or 120 pm < B < 400 pm.

[0063] According to a preferred embodiment of the invention, the following applies to a thickness C of a plate of the plate stack: 20 pm < C < 500 pm, preferably 150 pm < C < 500 pm or 250 pm < C < 500 pm.

[0064] According to a preferred embodiment of the invention, the following applies to a plate spacing D between directly adjacent plates of the plate stack: 1 pm < D < 100 pm, preferably 20 pm < D < 100 pm or 40 pm < D < 100 pm.

[0065] According to a preferred embodiment of the invention, the following applies to a total height H of the plate stack: 50 pm < H < 100 pm, preferably 300 pm < H < 1000 pm or 500 pm < H < 1000 pm.

[0066] The method according to the invention therefore makes it possible to drill through even relatively thick plates and plates that are relatively widely spaced from one another, using a fast and precise process. Especially for larger dimensions, the manufacturing process using known planar integration techniques is much slower.

[0067] According to a preferred embodiment of the invention, the micro-optic system comprises at least a second or further plate stack. The second or further plate stack of the micro-optic system can be produced using process steps (a) to (d). However, it is also possible for the second or further plate stack of the micro-optic system to be produced or to have been produced using planar technology and / or lithographic processes. In principle, other manufacturing processes are also possible.

[0068] According to a further preferred embodiment of the invention, the first plate stack and the second or further plate stack are aligned to one another in a method step (g). If several plate stacks are aligned to one another, a high degree of precision is required. However, this subsequent alignment of plate stacks or the apertures located therein is naturally less precise than the process-inherent positioning of the apertures within a plate stack if related apertures have been precisely created using the same method step. Therefore, it may be useful to arrange for the alignment of plate stacks to one another at transitions between different plate stacks where there is greater electron-optical insensitivity to misalignment. In this context, reference is again made to what was stated in connection with focused ion beam drilling.The sub-stacks described here essentially correspond to multiple stacks. In particular, critical lens transitions should, if possible, belong to the same plate stack, which was preferably produced by the method according to the invention comprising steps (a) to (d).

[0069] According to a further aspect of the invention, it relates to a micro-optics for a multi-particle beam system, which has been manufactured according to the method as described above in several embodiments.

[0070] According to a further aspect of the invention, this relates to a micro-optic system for a multi-particle beam system, in particular for a multi-beam particle microscope. The micro-optic system comprises a first multi-aperture plate made of metal and a second multi-aperture plate made of metal. For the aperture diameters A of the first multi-aperture plate and the second multi-aperture plate, A > 150 pm applies. Furthermore, for the thicknesses C of the first multi-aperture plate and the second multi-aperture plate, C > 250 pm applies. For the plate spacing D between the first multi-aperture plate and the second multi-aperture plate, D > 30 pm applies.

[0071] The micro-optics described are therefore relatively large and, what's more, made of metal. Such a micro-optics cannot be manufactured using conventional planar integration techniques, or only with considerable time and effort.

[0072] According to a further aspect of the invention, it relates to a multi-particle beam system, in particular to a multi-beam particle microscope, with a micro-optics as described above.

[0073] According to a preferred embodiment of the invention, during operation of the multi-particle beam system, a voltage U of U > 250 V, preferably U > 300 V or U > 350 V, can be applied to the first multi-aperture plate and / or to the second multi-aperture plate of the micro-optics. Applying such high voltages to a multi-aperture plate is normally not possible with known micro-optics manufactured using planar integration techniques. Instead, only voltages in the order of magnitude of less than 200 V can be used. Otherwise, arcing will occur between different multi-aperture plates. When using the aforementioned high voltages, sometimes significantly more than 250 V, relatively large plate spacings D are necessary.This is normally not possible using grown insulator layers such as silicon oxide, but it is possible using other manufacturing processes, because in these processes, the thicknesses of insulator layers are typically limited by the process. It is particularly advantageous that some of the described manufacturing processes or drilling methods according to the invention can also be used to drill through insulators (for example, using laser drilling).

[0074] According to a preferred embodiment of the invention, the multi-particle beam system further comprises a magnetic lens, which is arranged downstream of the micro-optics with respect to the particle-optical beam path of the multi-particle beam system during operation of the multi-particle beam system. The micro-optics comprises a final multi-aperture plate with respect to the particle-optical beam path of the multi-particle beam system. This final multi-aperture plate is magnetically conductive, with a permeability p r of the material of the final multi-aperture plate the following relation applies: p r > 1000, preferably p r > 10000 or p r> 15000. During operation of the multi-particle beam system, the final multi-aperture plate of the micro-optics is positioned within the magnetic field generated by the magnetic lens. This results in single particle beams passing through the micro-optics abruptly entering the magnetic field of the magnetic lens during operation of the multi-particle beam system, which provides the possibility of adjusting the azimuthal tilt of the single particle beams.

[0075] According to a preferred embodiment of the invention, the multi-particle beam system further comprises a controller configured to control the magnetic lens and adjust its magnetic field strength. Furthermore, the controller is configured such that, by changing the magnetic field strength of the magnetic lens, an azimuthal tilt of individual particle beams passing through the magnetic lens during operation is adjusted. Such an adjustment option is particularly interesting for the inspection of samples with a high aspect ratio: When examining samples with a high aspect ratio, it is often particularly important that the inspecting individual particle beams impinge on the sample surface telecentrically in order to be able to ideally scan the structures with the high aspect ratio.Another example application is samples located within the magnetic field of an objective lens system (magnetic immersion lenses). Charged particles experience rotation or Larmor rotation in the magnetic field due to the Lorentz force. If a sample to be scanned is still within the magnetic field, the rotation of the charged particles in the magnetic field is incomplete, and the azimuthal velocity component of the charged particles is not yet zero upon impact with the sample. This leads to an azimuthal tilt of individual particle beams. Such a tilt can be compensated for using the described arrangement of a final multi-aperture plate with high magnetic conductivity within a magnetic field of a magnetic lens, such as a field lens.

[0076] There are also applications where it is desired that charged single-particle beams pass through an objective lens at a slight angle. This can be the case, for example, if a sample surface is tilted relative to the particle-optical axis Z, i.e., if this axis Z is not exactly perpendicular to the sample surface.

[0077] In addition, it is possible, for example, to correct certain aberration terms of the objective lens using the described arrangement or using this passive multi-deflector.

[0078] According to another preferred embodiment, the material of the final multi-aperture 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 both high saturation induction and high maximum permeabilities.

[0079] There are various magnetically conductive materials with a permeability p suitable for the final multi-aperture plate in the state of the art. r > 1000. These include, among others, soft magnetic standard materials such as pure iron (e.g. Vacofer®), nickel-iron alloys with a nickel content of approximately 75% such as Mu-metal, Permalloy or Supermalloy, 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 Vacoflux®, or silicon-iron alloys with a silicon content of approximately 3% such as Trafoperm®. These materials are also commercially available as thin membranes, for example with a thickness of 25 pm, 50 pm, 100 pm or 250 pm. Due to their low thickness, plates made of such materials are generally suitable for a final multi-aperture plate.

[0080] According to a further aspect of the invention, this relates to a multi-particle beam system comprising: a particle source for generating a charged particle beam; a multi-beam generator through which the charged particle beam passes, forming a plurality of charged first individual particle beams that form a first field; first particle optics with a first particle-optical beam path, which is configured to image the generated first individual particle beams onto an object plane so that the first individual particle beams strike an object at impact locations that form a second field; an objective lens, in particular a magnetic objective lens, through which the first individual particle beams pass; and a controller;wherein the multi-beam generator comprises a micro-optic system with a plurality of successively arranged multi-aperture plates, which are each successively penetrated by the charged first individual particle beams, wherein the micro-optic system has a final multi-aperture plate with respect to the particle-optical beam path, which is magnetically conductive, wherein for a permeability number p; r of the material of the final multi-aperture plate the following relation applies: p r ä 1000, especially p r ä 10000 or p rä 15000, wherein the first particle optics comprises a magnetic field lens, wherein the final multi-aperture plate of the micro-optics is arranged within a magnetic field generated by the magnetic field lens during operation of the multiplicity particle beam system, wherein the controller is configured to control the magnetic field lens and to adjust its magnetic field strength, and wherein the controller is further configured such that an azimuthal tilt of the charged first individual particle beams is adjusted upon impact with the object and / or upon passing through the objective lens by means of a change in the magnetic field strength of the magnetic field lens.

[0081] It is again possible that the micro-optics of the multi-beam generator are manufactured according to the described method for manufacturing a micro-optics for a multi-particle beam system.

[0082] According to a preferred embodiment of the invention, the final multi-aperture plate and the magnetic field lens are arranged centered relative to one another with respect to their central aperture. This centering facilitates adjustment of the azimuthal tilt and its precision. According to a further preferred embodiment of the invention, the z-component Bz of the magnetic field B on the particle-optical axis Z at the final multi-aperture plate assumes a value for which the following relationship applies: 0.1 mT < Bz < 10.0 mT, preferably 1.0 mT < Bz < 10.0 mT. For this purpose, for example, for a given magnetic field, a distance dFF between the final multi-aperture plate and the lens center point of the magnetic lens can be set such that the relationship for the magnetic field Bz is satisfied.

[0083] 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 to adjust the azimuthal tilt of the first individual particle beams. This variation of the magnetic field strength is therefore a fine adjustment. It is possible that a lookup table is stored in a memory of the multiple particle beam system for various presets of magnetic field strengths B, for example, for different operating points of a multiple particle beam system, which allows the value for an azimuthal tilt of the first individual particle beams to be specifically adjusted. A nominal value is defined such that the nominal value corresponds to the case of a completely corrected azimuthal beam tilt at the object or at the sample surface or at a wafer surface.

[0084] According to a preferred embodiment of the invention, the material of the final multi-aperture plate is Permenorm®. However, other materials are also possible, for example, other soft-magnetic standard nickel-iron alloys with a nickel content of approximately 50%.

[0085] According to a further 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 another multi-particle beam system, for example, a lithography system.

[0086] According to a further preferred embodiment of the invention, the multi-beam particle system further comprises: a detection system with a plurality of detection regions forming a third field; a second particle optics system with a second particle-optical beam path, which is configured to image charged second single-particle beams emanating from the impact locations in the second field onto the third field of detection regions of the detection system; and a beam switch arranged in the first particle-optical beam path between the multi-beam particle source and the objective lens, and arranged in the second particle-optical beam path between the objective lens and the detection system; wherein the objective lens is penetrated by both the first single-particle beams and the second single-particle beams.

[0087] According to a further preferred embodiment of the invention, a second micro-optic system with a plurality of successively arranged multi-aperture plates is provided in the second particle-optical beam path, each of which is successively penetrated by the charged second individual particle beams. In this case, the micro-optic system has a final multi-aperture plate with respect to the particle-optical beam path, which is magnetically conductive, with a permeability p r of the material of the final multi-aperture plate, the following relation applies: p r > 1000, preferably p r > 10000 or p r> 15000. Furthermore, the second particle optics comprises a magnetic projection lens. During operation of the multi-particle beam system, the final multi-aperture plate of the second micro-optics is arranged within a magnetic field generated by the magnetic projection lens. In this embodiment of the invention, the controller is configured to control the magnetic projection lens and adjust its magnetic field strength. The controller is further configured such that, by changing the magnetic field strength of the magnetic projection lens, an azimuthal tilt of the charged second individual particle beams is adjusted upon impingement on the detection regions and / or upon passing through a contrast aperture arranged at the level of a beam crossing of the second individual particle beams.In this case, the second micro-optics with the final multi-aperture plate can again be manufactured according to the inventive method for producing a micro-optics for a multi-particle beam system, as described above in several embodiments. With the described configuration of the multi-particle beam system, it is possible to implement a multi-deflector not only in the first particle-optical beam path of a multi-particle beam system, but also in a second particle-optical beam path of the multi-particle beam system. The described effects and advantageous embodiments can be realized analogously to the described effects and embodiments in the first particle-optical beam path.

[0088] The various embodiments and aspects of the invention may be combined in whole or in part, provided that this does not result in technical contradictions. The invention will be better understood with reference to the accompanying figures. In these figures:

[0089] Fig. 1 : shows schematically a multi-particle beam system;

[0090] Fig. 2: shows schematically a structure of a micro-optics;

[0091] Fig. 3: shows schematically an alignment problem with multi-aperture plates;

[0092] Fig. 4: shows schematically process steps of an inventive

[0093] Manufacturing process for a micro-optic device;

[0094] Fig. 5: shows a flow chart of a manufacturing method according to the invention;

[0095] Fig. 6: shows schematically process steps of an inventive

[0096] manufacturing process;

[0097] Fig. 7: shows schematically process steps of an inventive

[0098] manufacturing process;

[0099] Fig. 8: shows schematically aspects of a manufacturing method according to the invention;

[0100] Fig. 9: shows schematically process steps of an inventive

[0101] manufacturing process;

[0102] Fig. 10: shows schematically a Manhattan electrode and a

[0103] multi-aperture plate;

[0104] Fig. 11 : shows schematically multi-aperture plates of a micro-optics;

[0105] Fig. 12: shows schematically aspects of a manufacturing process for a micro-optic device;

[0106] Fig. 13: shows another flow diagram of an inventive

[0107] manufacturing process;

[0108] Fig. 14: shows schematically particle-optical images through a symmetric and an asymmetric magnetic lens; and

[0109] Fig. 15: schematically illustrates an arrangement with a micro-optic and with a

[0110] Magnetic lens for the realization of a multi-deflector.

[0111] Fig. 1 schematically shows a multi-particle beam system 1 in the form of a multi-beam particle microscope 1. The multi-beam particle microscope 1 has a beam generation device 300 with a particle source 301, for example an electron source. A diverging particle beam 309 is collimated by a sequence of condenser lenses 303.1 and 303.2 and impinges on a multi-aperture arrangement 305, which forms a micro-optic system. The multi-aperture arrangement 305 comprises several multi-aperture plates 306 and a field lens 308. The multi-aperture arrangement 305 generates a plurality of individual particle beams 3 or individual electron beams 3. Center points of apertures of the multi-aperture plate arrangement are arranged in a field, which is imaged onto another field formed by beam spots 5 in the object plane 101.The distance between the centers of apertures of a multi-aperture plate 306 can be, for example, 5 pm, 100 pm, and 200 pm. The diameters A of the apertures are smaller than the distance between the centers of the apertures. Examples of diameters are 0.2 times, 0.4 times, and 0.8 times the distance between the centers of the apertures.

[0112] The multi-aperture arrangement 305 and the field lens 308 are configured to generate a plurality of focal points 323 of primary beams 3 in a grid arrangement on a surface 321. The surface 321 does not have to be a flat surface, but can be a spherically curved surface to accommodate field curvature of the downstream particle-optical system.

[0113] The multi-beam particle microscope 1 further comprises a system of electromagnetic lenses 103 and an objective lens 102, which image the beam foci 323 from the intermediate image area 325 into the object plane 101 in a reduced size. The first individual particle beams 3 pass through the beam switch 400 and a collective beam deflection system 500, with which the plurality of first individual particle beams 3 are deflected during operation and the image field is scanned. The first individual particle beams 3 impinging on the object plane 101 form, for example, a substantially regular field, wherein distances between adjacent impingement points 5 can be, for example, 1 pm, 10 pm, or 40 pm. The field formed by the impingement points 5 can, for example, have a rectangular or hexagonal symmetry.

[0114] The object 7 to be examined can be of any type, for example, a semiconductor wafer or a biological sample, and it can comprise an array of miniaturized elements or the like. The surface 15 of the object 7 is arranged in the object plane 101 of the objective lens 102. The objective lens 102 can comprise one or more electron-optical lenses. It can be, for example, a magnetic objective lens and / or an electrostatic objective lens.

[0115] The primary particles 3 striking the object 7 generate interaction products such as secondary electrons, backscattered electrons, or primary particles that have undergone a reversal of motion for other reasons, which emanate from the surface of the object 7 or from the first plane 101 or object plane 101. The interaction products emanating from the surface 15 of the object 7 are formed into secondary particle beams 9 by the objective lens 102. The secondary beams 9 pass through the beam switch 400 after the objective lens 102 and are fed to a projection system 200. The projection system 200 has an imaging system 205 with projection lenses 208, 209 and 210, a contrast aperture 214 and a multi-particle detector 207. Impact locations 25 of the second single-particle beams 9 on detection areas of the multi-particle detector 207 lie in a third field with a regular distance from one another.Example values ​​are 10 pm, 100 pm and 200 pm.

[0116] The multi-beam particle microscope 1 further comprises a computer system or a control unit 10, which in turn can be designed as a single or multi-part unit, and which is designed both to control the individual particle-optical components of the multi-beam particle microscope 1 and to evaluate and analyze the signals obtained with the multi-detector 207 or the detection unit.

[0117] Further information on such multi-beam particle beam systems or multi-beam particle microscopes 1 and components used therein, such as particle sources, multi-aperture plates and lenses, can be obtained from the international patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596 A1, WO 2011 / 124352 A1 and WO 2007 / 060017 A2 and the German patent applications DE 10 2013 016 113 A1 and DE 10 2013 014 976 A1, the disclosure of which is incorporated in its entirety by reference into the present application.

[0118] The multi-aperture arrangement 305 forms a micro-optic system 305, by means of which, in the example shown, during operation of the multi-particle beam system 1, the plurality of first individual particle beams 3 are initially generated at the first of the multi-aperture plates (so-called filter plate) and are also actively shaped at additional multi-aperture plates. The micro-optic system 305 itself can be designed in various ways.

[0119] Fig. 2 shows, by way of example, a micro-optics system 305 configured as a multi-beam generator 305. In the illustrated example, the multi-beam generator 305 comprises, in the z-direction, which corresponds to the propagation direction of the individual particle beams 3, a sequence of six multi-aperture plates 304, 306.1, 306.2, 306.3, 306.4, and 310, as well as a global condenser lens 307. Each of the multi-aperture plates 304, 306.1 to 306.4, and 310 comprises a plurality of apertures 351, each of which is penetrated by the plurality of individual particle beams 3. The cross-section through the apertures 351 in Figure 2 is not to scale.

[0120] The plurality of multi-aperture plates 304, 306.1, 306.2, 306.3, 306.4, and 310 are spaced apart from one another by spacers 83.1 to 83.5. Furthermore, a spacer 86 is provided between the final multi-aperture plate 310 and the global lens electrode 307. The plurality of first individual particle beams 3 are generated by the impact of a collimated particle or electron beam 309 upon passing through the first multi-aperture plate 304, which is also called a filter plate or pre-aperture plate. The pre-aperture plate 304 comprises a metallic layer 99 on its beam input side for stopping and absorbing the electrons of the electron beam 309 impinging thereon around the plurality of apertures 85. In the example shown, the material of the pre-aperture plate 304 is made of a conductive material, e.g. doped silicon, and is at ground potential.

[0121] The next multi-aperture plate is a multi-stigmator plate 306.1 in the example shown in Figure 2. The multi-stigmator plate 306.1 comprises a plurality of four or more electrodes 82, e.g., eight electrodes for each of the apertures. During operation of the multi-beam particle microscope 1, different voltages, for example, in the range between -20 V and +20 V, can be applied to each of these electrodes, thereby individually influencing each individual particle beam 3. For example, it is possible to use an antisymmetric voltage difference to deflect each individual particle beam 3 in any direction up to a few pm in order to pre-correct a distortion of the illuminating unit 100. An astigmatism pre-correction of each individual particle beam 3 can also be performed. With an offset voltage, each multipole element can additionally function as an individual lens.

[0122] The multi-aperture plates 306.2, 306.3, and 306.4 can, in principle, be any monolithic trajectory correction plates to which, in the example shown, a voltage V1, V2, and V3 is applied, respectively. It is also possible for the multi-aperture plates 306.2, 306.3, and 306.4 to form a single-lens array. Different apertures 351 in the same multi-aperture plate 306.2, 306.3, and 306.4 can be identical or different, for example, have different diameters, in order to account for a field dependence of the correction during the trajectory correction of the individual particle beams 3.

[0123] The multi-aperture plate 310 is a two-layer multi-aperture plate and comprises a plurality of ring electrodes 79 for the plurality of apertures, wherein each ring electrode is configured to individually change or correct a focal position of the first single-particle beam 3 passing through it. The upper layer is insulated from the layer or layer with the ring electrodes 79 and is made of a conductive material such as doped silicon. The field lens 307 comprises a ring electrode 84 to which a high voltage of, for example, 3 kV to 20 kV, e.g., 12 kV to 17 kV, can be applied. In the example shown, the condenser lens 307 provides a global electrostatic lens field for global focusing of the plurality of single-particle beams 3.

[0124] The micro-optics 305 shown in Figure 2 and its multi-aperture plates can, in principle, be manufactured using known manufacturing methods or using planar integration techniques. However, at least some multi-aperture plates, for example, the multi-aperture plates 306.2, 306.3, and 306.4, can also be manufactured using the manufacturing method according to the invention. Due to the special performance of such multi-aperture plates 306.2, 306.3, and 306.4 manufactured according to the invention (ability to apply relatively high voltages V, V2, V3 and relatively large plate spacings or large thickness of spacers / insulators 83.2, 83.3, 83.4, 83.5), it is also possible that, for example, the multi-aperture plate 310 with the ring electrodes 81 becomes superfluous.

[0125] Fig. 3 schematically shows an alignment problem with multi-aperture plates 350, each of which has been manufactured independently of one another, i.e., each one on its own. Fig. 3a schematically shows the provision of three plates 360 without openings. Fig. 3b schematically shows the use of a drilling means 900, which in principle can be of any type. In this respect, Fig. 3 is only concerned with the principle. The effective direction of the drilling means 900 is indicated schematically by the arrow in Fig. 3b. The drilling means 900 forms openings 351 in the plate 360, whereby the plate 360 ​​becomes a multi-aperture plate 350. It should be noted that, for reasons of ease of illustration, only one opening 351 is shown in Fig. 3, but of course there are several openings 351 in a multi-aperture plate 350. Fig. 3D now illustrates that the three multi-aperture plates 350.1, 350.2 and 350.3 to form a multi-aperture arrangement 305 or a micro-optic system 305. For this purpose, the conductive multi-aperture plates 350.1, 350.2, and 350.3 are aligned with each other, fixed, and insulated. In the example shown, this is achieved by the spacers 370.1 and 370.2.

[0126] 370.2. The openings 351.1, 351.2, and 351.3 are not exactly aligned, i.e., not centrally aligned. They are therefore not aligned. An exact arrangement or orientation relative to each other is not possible for the openings 351.1, 351.2,

[0127] 351.3 in the multi-aperture plates 350.1, 350.2, and 350.3 is very difficult, if not impossible. This is especially true if the multi-aperture plates 350.1, 350.2, and 350.3 are made of metal: They are then impermeable to visible light or infrared radiation, making optically based alignment, as typically used in die bonders, extremely difficult. Replacing semiconductor-based plates of a multi-aperture arrangement 305 with metal plates is therefore not readily possible.

[0128] However, the manufacturing method according to the invention offers a solution, in which, on the one hand, metal plates can be used to produce a micro-optic device 305 and, on the other hand, can be aligned with sufficient precision. Fig. 4 schematically shows the process steps of a manufacturing method according to the invention for a micro-optic device 305:

[0129] Fig. 4a first shows three plates 360.1, 360.2 and 360.3 for the micro-optics 305, which in the example shown are not only conductive but made of metal.

[0130] Fig. 4b shows the arrangement of plates 360.1, 360.2, and 360.3 relative to one another. Plates 360.1, 360.2, and 360.3 are fixed relative to one another and electrically insulated from one another by spacers 370.1 and 370.2. Spacers 370.1 and 370.2 can be made of silicon oxide, for example.

[0131] Fig. 4c now schematically shows the drilling of the plate stack with plates 360.1, 360.2, and 360.3 using a drilling tool 900. This is only shown schematically in Fig. 4c; the drilling direction is indicated by the arrow. It is important that the entire plate stack is drilled through at once, in the same drilling process, using the same drilling tool 900.

[0132] Fig. 4d shows the result of the drilling process: The apertures 351.1, 351.2, and 351.3 are perfectly aligned with each other, and the centers of the apertures 351.1, 351.2, and 351.3 are located centrally on the Z-axis in the example shown. Again, Fig. 4 only shows an exemplary sequence of apertures 351.1, 351.2, and 351.3; of course, the multi-aperture plates 350.1, 350.2, and 350.3 contain multiple apertures or sequences of apertures.

[0133] Furthermore, it is conceivable that drilling means 900 could be used to drill not only through plates 360.1, 360.2, and 360.3, but also through insulating plates or layers. Whether this is possible depends solely on the drilling method used.

[0134] Fig. 5 schematically shows a flow diagram of a manufacturing method according to the invention for a micro-optic system 305 for a multi-particle beam system 1: In a method step S1, a first plate 360.1 of the micro-optic system 305, which is electrically conductive, is first provided. In a method step S2, a second plate 360.2 of the micro-optic system 305, which is electrically conductive, is first provided.

[0135] In a method step S3, a plate stack is created. Creating a plate stack comprises stacking the first plate 360.1 of the micro-optics 305 and the second plate 360.2 of the micro-optics 305 one above the other, wherein the first plate 360.1 of the micro-optics 305 and the second plate 360.2 of the micro-optics 305 are fixed relative to one another in the plate stack and are electrically insulated from one another. This can be achieved, for example, by using insulating spacers 370.1, 370.2.

[0136] Then, in a method step S4, the entire produced plate stack is drilled through with at least the first plate 360.1 and the second plate 360.2 of the micro-optics 305, thereby producing both a first plurality of apertures 351.1 in the first plate 360.1 of the micro-optics 305 and a second plurality of apertures

[0137] 351.2 in the second plate 360.2 of the micro-optics 305. As a result, the sequence of apertures 350.1, 350.2 in the plates 360.1, 360.2 of the plate stack produced during the same drilling process is precisely aligned with one another, in a process-inherent manner. Optionally, the plate stack can further comprise at least one further and thus at least one third plate 360.3 of the micro-optics 305, which is electrically conductive. In this case, the third plate 360.3 of the micro-optics 305 is relative to the first plate 360.1 of the micro-optics 305 and the second plate

[0138] 360.2 of the micro-optics 305 and electrically insulated therefrom. The third plate of the micro-optics 305 is also drilled through during method step S4, thereby creating a third plurality of apertures 351.3 in the third plate 360.3 of the micro-optics 305. One or more of the aforementioned plates of the micro-optics 305 can be made of a metal. According to a preferred embodiment of the invention, all of the drilled plates are made of metal. However, it is also possible to provide, in addition to the conductive plates, other plates that are not conductive but are made of an insulating material, for example silicon dioxide.

[0139] The drilling of the plate stack according to method step S4 can be carried out in various ways: Examples of drilling methods include laser drilling, drilling by micro-EDM, mechanical high-speed micro-drilling, vibration drilling, ultrasonic drilling, or the use of a focused ion beam (FIB). For details on these methods, reference is made to the explanations in the general description of the invention. Optionally, in a further method step S5, the plate stack can be rinsed and drilling material removed through rinse holes in the first plate 306.1 of the micro-optics 305 and in the second plate 306.2 of the micro-optics 305. For a diameter S of the rinse holes in relation to the diameter A of the apertures in the first plate 306.1 of the micro-optics 305 and in the second plate 306.2 of the micro-optics 305, the following relationship can apply: S > 10A, preferably S > 100A.

[0140] A modified manufacturing method for a micro-optic unit 305 of a multi-particle beam system 1 is shown in the flow chart in Fig. 13: In this method, the method steps S1 to S3 are first carried out as described above. Before drilling through the plate stack according to step S4, in the described exemplary embodiment, in step S11, a space between the first plate 306.1 of the micro-optic unit 305 and the second plate 306.2 of the micro-optic unit 305 is filled with a liquid rinsing agent, and in step S12, the rinsing agent is cooled and thereby solidifies. Temperature control can be realized, for example, by carrying out the method within a process chamber whose internal temperature is adjustable, or the liquid is supplied heated and then cools down on its own. The entire plate stack is then drilled through in step S4.By arranging / providing the solidified rinsing agent, forces acting on plates 306.1 and 306.2 during drilling can be better absorbed, distributed, and dissipated. Bending of plates 306.1 and 306.2 can thus be better prevented. In a further method step S13, the rinsing agent is heated and thus liquefied. In this case, for example, the entire plate stack can be heated and the rinsing agent is heated along with it. In a further method step S14, the now liquid rinsing agent is removed from the intermediate space. The rinsing holes described above can be used for filling with the rinsing agent and for removing the rinsing agent.

[0141] Optionally, it is also possible for the entire plate stack to be annealed in a further process step. This may be necessary for a magnetically conductive final multi-aperture plate 350.f to ensure its magnetic conductivity, for example, for use of the micro-optics 305 in combination with a magnetic lens 308 in a multi-particle beam system 1 as a magnetic multi-deflector.

[0142] Fig. 6 schematically shows process steps of a manufacturing method according to the invention. In the embodiment shown in Fig. 6, the plates 360 of the micro-optics 305 are non-conductive, or not entirely conductive. Their conductivity is present only in sections, namely in the area around the apertures 351 that are yet to be formed:

[0143] Specifically, three inherently non-conductive plates 360 are initially provided for the micro-optics 305. The plates 360 can have an insulating material as the base material, for example, a ceramic. Coarse apertures 361 can then be formed in these plates 360. The coarse apertures 361 are larger than the final apertures 362 of the micro-optics 305.

[0144] In a further process step (see Fig. 6c), the coarse apertures 362 are metallized. The metallization of the coarse apertures 361 can be performed, for example, by sputtering or electroplating. Conductive regions 363 are formed around or adjacent to the coarse apertures 362. These, in turn, have openings 363. Their diameter is smaller than the diameter of the final apertures 351 of the micro-optics 305.

[0145] In a further process step, the plates 360.1, 360.2, and 360.3 are fixed relative to each other with the metallized coarse apertures 361 and arranged so as to be electrically insulated from each other. The spacers 370.1 and 370.2 can be electrically insulating, but they do not necessarily have to be, since the plate material of the plates 360.1, 360.2, and 360.3, as a ceramic material, can already be sufficiently insulating. The openings 363.1, 363.2, and 363.3 are not perfectly aligned with each other. However, they do not have to be at this stage of the manufacturing process:

[0146] As shown in Fig. 6e, the metallized coarse apertures 361 and the conductive regions 362.1, 362.2, and 362.3 are subsequently drilled through. Fig. 6e again schematically shows a drilling means 900 and its direction of movement.

[0147] As a result, apertures 351 .1, 351 .2 and 351 .3 are formed which are perfectly aligned or, inherently to the process, exactly aligned with one another, as shown in Fig. 6f.

[0148] Using the manufacturing method described in Fig. 6, not only monolithic multi-aperture plates 350.1, 350.2 and 350.3 can be produced, which are already (fully) conductive per se. Instead, it is also possible to realize ring electrodes using the manufacturing method according to the invention. The ring electrodes are formed by the conductive regions 362.1, 362.2 and 362.3 in the example shown. The supply of lines to the individual ring electrodes must be realized in a further process step; this is more complex than with monolithic multi-aperture plates 350, but can also be realized. For this purpose, a metal printing process, for example, is suitable even before the plate stack is assembled. It is also possible, for example, for conductor tracks to be applied using a combination of sputtering and electroplating.

[0149] Fig. 7 schematically shows process steps of a manufacturing method according to the invention for a micro-optic device 305. The plate stack shown in Fig. 7a with the plates 360.1, 360.2, and 360.3 can, for example, be manufactured as described in connection with Figs. 4a and 4b. Unlike what was shown in connection with Fig. 4c, however, the drilling of the plate stack in Fig. 7a is different, specifically with regard to the drilling direction: The plate stack is drilled at an angle. The resulting angled apertures 351.1, 351.2, and 351.3 are also precisely aligned with one another, as indicated by the dotted auxiliary lines in Fig. 7B. However, with this oblique drilling, apertures 351.1, 351.2, and 351.3 are not exactly circular, but slightly elliptical. The degree of ellipticity depends on the degree of inclination during drilling relative to the normal of the plate stack.

[0150] Fig. 8 schematically shows aspects of a manufacturing method according to the invention, wherein the drilling of the plate stack is carried out using a focused ion beam (FIB). The plate stack shown comprises a total of six membranes 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, which indicates a frame region, and reference numeral 381, which indicates a membrane region.

[0151] The plate stack shown is intended to have the functionality of a single lens, for example, after drilling through the entire plate stack. For this reason, voltages U1, U2 and U3 are indicated schematically in Fig. 8. However, instead of a single plate 360 ​​with the total height H over the entire plate width, two membranes with the small thickness h are provided. The corresponding voltage is applied to the lower and the upper membrane. From an electron optical point of view, the fact that cavities 382.1, 382.2 and 382.3 are provided between the membranes 360.1 and 360.2, between 360.3 and 360.4 and between 360.5 and 360.6 makes no significant difference. Insulating spacers 370.1 and 370.2 are arranged in a known manner between the respective pairs of membranes.When drilling through the plate stack, the focused ion beam can now be used in the same drilling process, starting from the top, to first drill through the uppermost membrane 360.1, then the next membrane 360.2, and so on. This can again be done in principle in the same process step, or without the position of the FIB column having to be changed, at least not in the x-direction or y-direction. This means that the x, y positions of the FIB column and thus also the x, y positions of the apertures 351 to be created are fixed. The fact that only the thin membrane sections with the height h need to be drilled through can take into account the fact that a focused ion beam has only a relatively small depth of field and can therefore only drill through relatively thin layers. Drilling through the entire plate stack as shown in Fig.8 is therefore particularly suitable for plate stacks with a low overall height, for example up to a height of a few micrometers.

[0152] For cases in which the plate stack as a whole has a greater height and the shallow depth of field of the focused ion beam becomes a problem, the process sequence shown in Fig. 9 represents a solution: The entire stack with plates 360.1 to 360.6 is divided into four sub-stacks. In particular, plates 360.2 and 360.3 as well as plates 360.4 and 360.5 each form independent stacks as defined in patent claim 1. The individual stacks or sub-stacks are then drilled through separately using the FIB or the focused ion beam. The stack according to Fig. 9b forms a stack in which a lens transition takes place. Here, the alignment of the apertures generated 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 shown in Fig. 9c. The transitions within the same lens, on the other hand, are not so critical.Therefore, it is possible to assemble the sub-stacks after separately drilling the partial stacks (Figs. 9b and 9c) and the individual plates or membranes (Figs. 9a and 9d) and to perform the appropriate alignment without any significant loss of performance of the micro-optics 305. This assembly of the sub-stacks is indicated by the bracket in Fig. 9. This, in turn, creates the micro-optics 305.

[0153] In principle, it is possible for the plurality of apertures in the plates of a plate stack to be created successively. However, it is also possible for the plurality of apertures in the plates to be created at least partially simultaneously. An example of this is shown in Fig. 10: Fig. 10a shows a Manhattan-type electrode as drilling means 900. This has a plurality of electrodes 902 arranged on a base element 901. In principle, the Manhattan-type electrode is therefore a multi-electrode. With this, several openings can be created simultaneously in batches at different positions in a plate 360. The result of the drilling process is shown in Fig. 10b: This shows a multi-aperture plate 350 with a plurality of circular apertures 351, the arrangement of which corresponds to the arrangement of the electrodes 902.

[0154] The Manhattan-type electrode shown in Fig. 10 can be used, for example, in a micro-EDM process. However, the principle is also transferable to other drilling processes.

[0155] Fig. 11 schematically shows several multi-aperture plates 350 of a micro-optics system 305. Fig. 11a shows a plurality of round apertures 351, each of which has the same diameter and is regularly arranged. Fig. 11b shows a multi-aperture plate 350 with circular apertures 351, the diameter of which, however, varies within the multi-aperture plate or depends on the position of the aperture in the respective plate 350. In the example shown, the diameter of the apertures 351 shows a radial dependence on the distance from the center C in the multi-aperture plate 350.

[0156] Fig. 11 c shows a multi-aperture plate 350 with elliptical apertures 351. Its longitudinal axis I varies depending on the center M, namely in terms of orientation and size.

[0157] All multi-aperture plates 350 shown in Fig. 11 are monolithic aperture plates 350, to each of which only a single voltage is applied. Due to the conductivity of the plates 350, the apertures 351 create an effect, or lens effect, whose magnitude then depends only on the size and shape of the aperture.

[0158] In principle, the shape of the apertures 351 in the plates 360, 350 of the plate stack can be round, elliptical, n-fold, or irregularly shaped. The apertures themselves are preferably arranged using a grid, for example, a hexagonal grid. However, they can also be arranged, for example, in a square or rectangular grid.

[0159] According to one embodiment, adjacent apertures 351 in the plates of the plate stack have a distance B for which the following applies: 70 pm < B < 400 pm, preferably 90 pm < B < 400 pm or 120 pm < B < 400 pm.

[0160] For a thickness C of a plate 360, 350 of the plate stack, for example, the following may apply: 20 pm < C < 500 pm, preferably 150 pm < C < 500 pm or 250 pm < C < 500 pm. According to one embodiment, the following may apply to a plate spacing D between adjacent plates 350, 360 of the plate stack: 1 pm < D < 100 pm, preferably 20 pm < D < 100 pm or 40 pm < D < 100 pm.

[0161] According to one embodiment of the invention, the following relationship applies to a total height H of the plate stack: 50 pm < H < 1000 pm, preferably 300 pm < H < 1000 pm or 500 pm < H < 1000 pm. The total height H of the plate stack is understood to be the height of the plate stack that is simultaneously drilled through by a drilling means 900. Of course, the micro-optics 305 can also have at least a second or at least one further plate stack. It is possible for the second or further plate stack of the micro-optics to also be produced by means of the described method according to the invention. However, it is also possible for the second or further plate stack of the micro-optics 305 to be produced by other methods, for example by means of planar technology and / or lithographic methods. The second or further plate stack can then be aligned relative to the first plate stack.

[0162] With a correspondingly large dimensioning of the micro-optics 305, for example with an aperture diameter A with A > 150 pm, a thickness C of the multi-aperture plates 350 with C > 250 pm and a plate spacing D between the multi-aperture plates 350 of D > 30 pm, a relatively large micro-optics 305 can be provided. Relatively large voltages U can be applied to this relatively large micro-optics 305 during operation of a multi-particle beam system, for example U > 250 V, preferably U > 300 V and U > 350 V. This is particularly advantageous in multi-particle beam systems that operate with a large number of individual particle beams 3, since in such systems the field dependence of imaging errors, for example an image field curvature or an image field astigmatism, is particularly large in the edge regions of a multi-particle beam arrangement of a large grid.

[0163] Fig. 12 schematically shows aspects of another manufacturing method for a micro-optic device 305. In contrast to the methods already described above, an arrangement of different plates one above the other or of different layers one above the other is no longer drilled together; instead, a negative mold 910 is provided, around which various layers are first built up. The negative mold 910 is removed at the end of the process, so that apertures 911 defined by the negative mold 910 are inherently precisely aligned with one another. This example also avoids complex alignment problems. Specifically, the negative mold as such can be provided in a first method step. This can, for example, have a Manhattan-like structure that defines the later position of apertures 911.In addition, this negative mold can also be used to provide individual electrodes, such as ring electrodes or lines for supplying voltage to the electrodes. This central negative mold, which defines at least the dimensions of later apertures 911, can be designed in various ways. For example, it can be photoresist, silicon dioxide, etched metal (lidar process), coated metal (for deposition purposes), and so on. In Fig. 12a, the negative mold 910 is schematically shown as a central block. This central block is arranged on a substrate 390. This can be, for example, a wafer, for example made of silicon.

[0164] After providing this basic structure, including the negative mold 910, various layers can be deposited on the substrate 390. In the example shown, for example, a first metallic layer 392 can be deposited on the substrate 390, for example by sputtering or by sputtering and electroplating.

[0165] Subsequently, another layer 393 is deposited on the conductive layer 392. This layer is essentially an insulating layer 393. This layer can either be insulating from the outset (for example, deposition of an insulator such as silicon dioxide via sputtering), or the layer can be initially deposited electroplated and then, through heat treatment, lose its original electrical conductivity and become an insulator. Electrolytic processes for insulators are, in principle, known from the prior art in other contexts.

[0166] The described deposition processes of alternating conductive and non-conductive layers can be repeated. In the example shown, a metallic layer 394 is deposited, followed by another insulating layer 395, followed by another metallic layer 396, and so on. At the end of the process, the negative mold 910 is removed: This is shown schematically in Fig. 12b. The apertures 911 formed in this process are precisely aligned with each other.

[0167] The trick, in which insulators are essentially applied electrolytically and only become insulators upon heat treatment or baking, has the advantage that, in principle, all layers 392 to 396 can be applied electrolytically. This simplifies the process, eliminating the need for machine changes when applying different layers. Dealing with contaminants is also less problematic with electroplating processes than with sputtering processes.

[0168] Fig. 14 schematically illustrates particle-optical images through a symmetrical and an asymmetrical magnetic lens. The occurrence of beam tilts is illustrated schematically. Fig. 14a shows the imaging through a symmetrical magnetic lens 700. In principle, the magnetic lens 700 can be an objective lens, a field lens, a projection lens, or another magnetic lens. In this respect, only the principle is illustrated here. The Z component Bz of the magnetic field generated by the lens 700 is plotted on the Y-axis. With respect to the particle-optical axis Z, in front of the magnetic lens 700 there is an object G to be imaged, which is represented by an upright arrow. It is important that the object G to be imaged is outside the magnetic field of the magnetic lens 700. The particle-optical image B is created behind the magnetic lens 700. An example is shown in Fig.Figure 14A shows a particle-optical beam path for a parallel beam or field beam, which is imaged through the focal point F in the focal plane E. The center beam is also shown. Figure 14a thus shows a very general imaging situation through a magnetic lens 700.

[0169] Below the schematically sketched beam paths through the magnetic lens 700, the azimuthal velocity component v aZ imutai of a particle beam 3, 9 moving parallel to the particle-optical axis Z. Before the charged particle beam 3, 9 enters the magnetic lens 700 or its magnetic field B or Bz, the azimuthal velocity component v aZimutai zero. Upon entering the magnetic field B or Bz of the magnetic lens 700, the charged particles or particle beams 3, 9 begin to rotate, the azimuthal velocity component Vazimutai increases and reaches a maximum value in the center of the magnetic lens 700. Subsequently, the azimuthal velocity component Vazimutai decreases again and the charged particles or the charged particle beams 3, 9 leave the magnetic lens 700 without an azimuthal velocity component, i.e. v aZ imutai = 0.

[0170] For comparison, Fig. 14b shows the particle-optical beam path for the case where the magnetic lens 700 is a magnetic immersion lens. In this case, the object G to be imaged, or an object, is located within the magnetic field B or Bz of the magnetic lens 700. It is crucial that the magnetic field B or Bz, which the charged particles or electrons experience and fly through, is not symmetrical, but asymmetrical: An off-axis electron, which emanates from the object G parallel to the particle-optical axis, starts without an azimuthal velocity component. It then rotates in the magnetic lens 700 and, due to the asymmetry, leaves the magnetic field with an azimuthal velocity component. Therefore, v azimutai * 0. This azimuthal velocity component leads to a tilt of the electron beams, or generally of the charged particle beams. As a result, parallel beams, for example, no longer meet homocentrically at the focal plane E. The situation shown in Fig. 14b is therefore typical, for example, for multi-beam particle microscopes 1 in which the objective lens 102 is a magnetic immersion lens. Thus, beam tilts occur when the beam hits a sample 7.

[0171] It is now a fundamental idea of ​​a partial aspect of the invention that the beam tilts described above can not only be caused by an asymmetric magnetic field from the perspective of charged particle beams, but can also be compensated: If charged particles or particle beams 3, 9 suddenly enter a magnetic field, this corresponds in principle to an asymmetrical flight through the magnetic field of a magnetic lens 700. By means of a corresponding trick, it is therefore possible to compensate for unwanted beam tilts in the particle-optical beam path or to specifically adjust beam tilts in the particle-optical beam path.

[0172] Fig. 15 schematically illustrates an arrangement with a micro-optic system 305 and a magnetic lens for implementing a multi-deflector. The arrangement shown in Fig. 15 can, for example, be integrated into the multi-beam particle microscope 1 shown in Fig. 1; in this case, the magnetic lens corresponds to the magnetic lens 308. This will be assumed as an example below.

[0173] The micro-optics 305 has a plurality of successively arranged multi-aperture plates 350.1, 350.2, and 350.3, each of which is successively penetrated by charged first single-particle beams 3. The micro-optics 305 can be manufactured, for example, by means of the inventive method for manufacturing a micro-optics 305 for a multi-particle beam system 1. The micro-optics 305 has, relative to the first particle-optical beam path, a final multi-aperture plate 350.f, which in the example shown corresponds to the multi-aperture plate 350.3. This final multi-aperture plate 350.f is magnetically conductive. The permeability p r of the material of the final multi-aperture plate satisfies the relation p r > 1000, especially p r > 10000 or p r> 15000. The material of the final multi-aperture plate 35O.f can be, for example, Permenorm® or another material. The final multi-aperture plate 35O.f is arranged centered relative to the magnetic field lens 308 with respect to its central aperture 351.c. To provide an adjustment or correction option for an azimuthal tilt of the charged first single-particle beams 3a, 3b, 3c, the final multi-aperture plate 35O.f of the micro-optics 305 is arranged within the magnetic field 701 generated by the magnetic field lens 308 during operation of the multi-particle beam system 1. The magnetic field 701 of the magnetic field lens 308, or a region in which the magnetic field 701 of the magnetic lens 308 is present, is shown schematically in a highly simplified manner in Fig. 15 by the dotted area.

[0174] Due to the magnetic conductivity of the final multi-aperture plate 35O.f, the magnetic field 701 of the magnetic lens 308 in Fig. 15 is sharply delimited in practice, and a sudden entry of the charged first single-particle beams 3a, 3b, and 3c into the magnetic field 701 can be realized. The azimuthal tilt of the first single-particle beams 3a, 3b, 3c is essentially proportional to the magnetic field strength and dependent on the field height or the distance of the charged single-particle beam 3 under consideration from the particle-optical axis Z. Accordingly, in the example shown, the charged particle beam 3a experiences an upward tilt and the charged particle beam 3c a downward tilt, while the axial beam 3b experiences no tilt on the particle-optical axis Z.

[0175] By a schematic representation of the geometric main axis A xof the field lens 308 as well as by the two distances dFF and d1, the asymmetry of the magnetic field 701 is also schematically illustrated: The distance dFF between the end of the final multi-aperture plate 35O.f and a center C of the magnetic field lens 308 along the particle-optical axis Z is smaller than the distance d1 from the center C of the magnetic field lens 308 to the end of the effective region of the magnetic field. In the example shown, dFF < d1 therefore applies. In the example shown, during operation of the multi-particle microscope 1, for example, dFF is selected such that the following relationship applies to the magnetic field 701 or to the magnetic field Bz on the axis Z at the final multi-aperture plate 35O.f: 0.1 mT < Bz < 10.0 mT, in particular 1.0 mT < Bz < 10.0 mT.

[0176] The controller 10 of the multi-particle beam system 1, or a part of the controller 10.1, is configured to control the magnetic field lens 308 and adjust its magnetic field strength. Furthermore, the controller 10, or a part of the controller 10.1, is further configured such that, by changing the magnetic field strength of the magnetic field lens 308, an azimuthal tilt of the charged first individual particle beams 3a, 3b, 3c, or generally of the charged first individual particle beams 3, is adjusted upon impact with the object 7 and / or upon passing through the objective lens 102 of the multi-particle beam system 1.

[0177] Furthermore, in the example shown, to adjust the azimuthal tilt of the first single-particle beams 3, the magnetic field strength of the magnetic field lens 308 is varied by a maximum of + / - 50% of its nominal value. The nominal value is defined such that it corresponds to the value of a fully corrected azimuthal beam tilt at the object 7 or at the object surface, such as a wafer surface.

[0178] Fig. 15 shows a concrete example of a magnetic multi-deflector. This example describes a concrete arrangement of the magnetic multi-deflector in the particle-optical beam path, in the example shown, in the primary beam path or immediately after the multi-beam generator 305 or the micro-optics 305, by means of which the plurality of charged first individual particle beams 3 in the multi-particle beam system are generated in the first place. Nevertheless, it is in principle possible to provide an arrangement with a micro-optics 305 and a magnetic lens 700 at other positions in the particle-optical beam path, both in the primary beam path and in the secondary beam path. The magnetic lens therefore does not have to be a field lens 308; instead, it can be any magnetic lens 700.

[0179] Furthermore, it is in principle possible for the charged particle beams to not abruptly enter a magnetic field 701 of a magnetic lens 700, but rather to merely abruptly exit the magnetic field of a magnetic lens 700. A fundamental condition for the possibility of adjusting an azimuthal tilt of charged single-particle beams is merely the asymmetry of the magnetic field through which the charged single-particle beams pass. Therefore, instead of arranging a final multi-aperture plate of a micro-optic system within a magnetic field of a magnetic lens, an initial, i.e., first, multi-aperture plate of a micro-optic system can also be arranged within a magnetic field of a previously arranged magnetic lens.

[0180] The exemplary embodiments described above are not intended to limit the invention, but merely serve to improve understanding of the invention. They may be combined in whole or in part, provided that no technical contradictions result.

[0181] List of reference symbols

[0182] 1 multi-particle beam system, multi-beam particle microscope primary particle beams, first single particle beams

[0183] Beam spots, impact points

[0184] Object, sample, wafer secondary particle beams, second single particle beams

[0185] Computer system, control

[0186] Sample surface, wafer surface

[0187] Image point of a second single particle beam

[0188] Multipole electrode

[0189] Ring electrode

[0190] spacers

[0191] Ring electrode

[0192] aperture

[0193] spacers

[0194] Absorbing and conductive layer

[0195] Object level

[0196] objective lens

[0197] Field lens

[0198] axis

[0199] Beam crossing, cross-over

[0200] detector system

[0201] Projection lens system

[0202] Projection lens

[0203] Multi-particle detector

[0204] Projection lens

[0205] Projection lens

[0206] Projection lens

[0207] Beam crossing, cross-over

[0208] Aperture filter, contrast diaphragm

[0209] Collective anti-deflection system

[0210] Beam generating device

[0211] Particle source

[0212] Collimation lens system

[0213] Multi-aperture array, filter plate

[0214] Microoptics, multi-aperture array, multi-beam particle generator

[0215] Multi-aperture plate

[0216] Field lens, aperture plate

[0217] Field lens 09 Particle beam 10 Multi-aperture plate 21 Intermediate image plane 23 Beam foci 33 Holding area 35 Membrane area 50 Multi-aperture plate 51 Aperture 60 Plate 61 Coarse aperture

[0218] 362 Conductive area 363 Opening in the conductive area 370 Spacer 380 Frame area 381 Membrane area

[0219] 382 Cavity 390 Wafer 391 Metallic layer

[0220] 392 Layer 393 Layer 394 Layer 395 Layer 396 Layer 400 Beam switch, magnet arrangement

[0221] 500 Scan deflector 600 Moving table or positioning device 700 Magnetic lens 701 Magnetic field

[0222] 900 drilling material 901 base element

[0223] 902 Manhattan-type electrode 910 Negative mold, photoresist A Central axis C Lens center of the magnetic lens E Plane F Focus

[0224] G Object B Image

[0225] Bz z-component of the magnetic field

[0226] Z axis

[0227] M center

[0228] H Height of frame section h Height of membrane x direction y direction z direction

[0229] I Longitudinal axis dFF Distance between final multi-aperture plate and lens center of the magnetic lens d1 Distance

Claims

Patent claims 1. A method for manufacturing a micro-optics for a multi-particle beam system, comprising the following steps: (a) providing a first plate of the micro-optics which is electrically conductive; (b) providing a second plate of the micro-optics which is electrically conductive; (c) producing a plate stack comprising stacking the first plate of the micro-optics and the second plate of the micro-optics one above the other, wherein the first plate of the micro-optics and the second plate of the micro-optics are fixed relative to each other in the plate stack and are electrically insulated from each other; and (d) drilling through the entire produced plate stack with at least the first plate and the second plate of the micro-optics and thereby producing both a first plurality of apertures in the first plate of the micro-optics and a second plurality of apertures in the second plate of the micro-optics.

2. The method according to claim 1, wherein the first plate of the micro-optics and / or the second plate of the micro-optics is metallic.

3. Method according to one of the preceding claims, wherein the plate stack further comprises at least one further or thus at least one third plate of the micro-optics which is electrically conductive, and wherein the third plate of the micro-optics is fixed relative to the first plate of the micro-optics and the second plate of the micro-optics and is electrically insulated therefrom, and wherein the third plate of the micro-optics is also drilled through when carrying out method step (d), so that a third plurality of apertures is thereby produced in the third plate of the micro-optics.

4. Method according to the preceding claim, wherein the third plate of the micro-optics is metallic.

5. The method according to claim 2 or 4, wherein the first plate and / or the second plate and / or the third plate is magnetically conductive; and wherein for a permeability r of the material of the plate the following relation applies: |j r 1000, especially r s 10000 or r s 15000.

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

7. The method according to any one of claims 1 to 5, wherein the drilling of the plate stack in step (d) is carried out by means of micro-EDM.

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

9. The method according to any one of claims 1 to 5, wherein the drilling of the plate stack in step (d) is carried out by means of vibration drilling or by means of ultrasonic drilling.

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

11. Method according to one of the preceding claims, wherein at least one of the plates of the plate stack has an insulating material as the base material, in particular a ceramic as the base material, and wherein the method further comprises the following steps, which are carried out before method steps (a) to (d): (e) creating a plurality of coarse apertures in the at least one plate with the insulating material as the base material; and (f) metallizing the coarse apertures; wherein, during the subsequent execution of process step (d), the metallized coarse apertures are pierced and the plurality of apertures are thus formed.

12. Method according to the preceding claim, wherein the metallization of the coarse apertures is carried out by sputtering and / or by electroplating.

13. The method according to any one of the preceding claims, wherein in step (d) the plurality of apertures in the plates of the plate stack are produced simultaneously.

14. The method according to any one of claims 1 to 12, wherein in method step (d) the plurality of apertures in the plates of the plate stack are successively produced.

15. Method according to one of the preceding claims, wherein the plurality of apertures each have a diameter A, where: 40pm < A < 400pm, in particular 80pm < A < 400pm or 110pm < A < 400pm.

16. The method according to the preceding claim, wherein the shape of the apertures in the plates of the plate stack is round, elliptical, n-fold or irregularly shaped.

17. Method according to one of the preceding claims, wherein adjacent apertures in the plates of the plate stack have a distance B for which the following applies: 70pm < B < 400pm, especially 90pm < B < 400pm or 120pm < B < 400pm.

18. Method according to one of the preceding claims, wherein for a thickness C of a plate of the plate stack: 20pm < C < 500pm, especially 150pm < C < 500pm or 250pm < C < 500pm.

19. Method according to one of the preceding claims, wherein for a plate spacing D between adjacent plates of the plate stack: 1 pm < D < 100pm, especially 20pm < D < 100 pm or 40pm < D < 100pm.

20. Method according to one of the preceding claims, wherein the following applies to a total height H of the plate stack: 50pm < H < 1000pm, in particular 300pm < H < 1000pm or 500pm < H < 1000pm.

21. Method according to one of the preceding claims, further comprising the following step: after drilling according to step d), rinsing the plate stack and removing drilling material through rinsing holes in the first plate of the micro-optics and in the second plate of the micro-optics, wherein the following relation applies to a diameter S of the rinsing holes in relation to the diameter A of the apertures in the first plate of the micro-optics and in the second plate of the micro-optics: S > 10A, in particular S > 100A.

22. A method according to the preceding claim, further comprising the steps of: prior to the piercing according to step (d) Filling a space between the first plate of the micro-optics and the second plate of the micro-optics with a liquid detergent, and - cooling the detergent and thereby solidifying the detergent; and after drilling according to step (d) Heating the detergent and thereby liquefying it; and removing the detergent from the space.

23. The method of claim 5, further comprising the step of: after drilling according to step (d) Annealing the plate stack.

24. Method according to one of the preceding claims, wherein the micro-optics comprises at least a second or further plate stack.

25. Method according to the preceding claim, wherein the second or further plate stack of the micro-optics is produced by means of method steps (a) to (d); or wherein the second or further plate stack of the micro-optics is produced by means of planar technology and / or lithographic methods.

26. A method according to the preceding claim, wherein the method further comprises the following method step: (g) Aligning the first stack of plates and the second or further stack of plates with each other.

27. Micro-optics for a multi-particle beam system, manufactured according to the method of any one of the preceding claims.

28. Micro-optics for a multi-particle beam system, wherein the micro-optics comprises a first multi-aperture plate consisting of metal and a second multi-aperture plate consisting of metal, wherein the aperture diameters A of the first multi-aperture plate and the second multi-aperture plate are each: A > 150 pm where the thicknesses C of the first multi-aperture plate and the second multi-aperture plate are each equal to: C > 250 pm; and where the plate spacing D between the first multi-aperture plate and the second multi-aperture plate is equal to: D > 30 pm.

29. A multi-beam particle beam system, in particular a multi-beam particle microscope, comprising a micro-optics system according to one of claims 27 to 28.

30. Multi-particle beam system according to the preceding claim, wherein during operation of the multi-particle beam system a voltage U can be applied to the first multi-aperture plate and / or to the second multi-aperture plate with U > 250V, in particular U > 300V or U > 350V.

31. A multiplicity particle beam system according to any one of claims 27 to 30, further comprising a magnetic lens which, with respect to the particle-optical beam path of the multiplicity particle beam system, is arranged downstream of the micro-optics during operation of the multiplicity particle beam system, wherein the micro-optics, with respect to the particle-optical beam path of the multiplicity particle beam system, comprises a final multi-aperture plate which is magnetically conductive, wherein for a permeability p r of the material of the final multi-aperture plate the following relation applies: p r > 1000, especially p r > 10000 or p r> 15000; and wherein the final multi-aperture plate of the micro-optics is arranged within a magnetic field generated by the magnetic lens during operation of the multi-particle beam system.

32. A multi-particle beam system according to the preceding claim, further comprising a controller, the controller being configured to control the magnetic lens and adjust the magnetic field strength thereof, the controller being further configured to adjust an azimuthal tilt of individual particle beams passing through the magnetic lens during operation by changing the magnetic field strength of the magnetic lens.

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

34. A multiplicity particle beam system comprising: a particle source for generating a charged particle beam; a multi-beam generator through which the charged particle beam passes, forming a plurality of charged first individual particle beams that form a first field; a first particle optics system with a first particle-optical beam path, configured to image the generated first individual particle beams onto an object plane, so that the first individual particle beams strike an object at impact locations that form a second field; an objective lens, in particular a magnetic objective lens, through which the first individual particle beams pass; and a controller;wherein the multi-beam generator has a micro-optic system with a plurality of successively arranged multi-aperture plates, which are each successively penetrated by the charged first individual particle beams, wherein the micro-optic system has a final multi-aperture plate with respect to the particle-optical beam path, which is magnetically conductive, wherein for a permeability number p; r of the material of the final multi-aperture plate the following relation applies: p r ä 1000, especially p r ä 10000 or p rä 15000, wherein the first particle optics comprises a magnetic field lens, wherein the final multi-aperture plate of the micro-optics is arranged within a magnetic field generated by the magnetic field lens during operation of the multi-particle beam system, wherein the controller is configured to control the magnetic field lens and to adjust its magnetic field strength, and wherein the controller is further configured such that an azimuthal tilt of the charged first individual particle beams is adjusted upon impact with the object and / or upon passing through the objective lens by means of a change in the magnetic field strength of the magnetic field lens.

35. A multi-particle beam system according to the preceding claim, wherein the final multi-aperture plate and the magnetic field lens are arranged centered relative to each other with respect to its central aperture.

36. A multi-particle beam system according to any one of claims 34 to 35, wherein the z-component Bz of the magnetic field B on the particle-optical axis Z at the final multi-aperture plate assumes a value for which the following relation applies: 0.1 mT < Bz < 10.0 mT, in particular 1.0 mT < Bz < 10.0 mT.

37. A multi-particle beam system according to any one of claims 34 to 36, wherein for adjusting the azimuthal tilt of the first single particle beams, the magnetic field strength Bz of the magnetic field lens is varied by a maximum of +-50% of its nominal value.

38. A multi-aperture particle beam system according to any one of claims 34 to 37, wherein the material of the final multi-aperture plate is Permenorm®.

39. A multi-particle beam system according to any one of claims 34 to 38, wherein the multi-particle beam system is a multi-beam particle microscope.

40. A multi-beam particle beam system according to any one of claims 34 to 39, further comprising: a detection system having a plurality of detection regions forming a third field; a second particle optics system having a second particle-optical beam path, configured to image charged second single-particle beams emanating from the impact locations in the second field onto the third field of detection regions of the detection system; and a beam splitter arranged in the first particle-optical beam path between the multi-beam particle source and the objective lens, and arranged in the second particle-optical beam path between the objective lens and the detection system; wherein the objective lens is traversed by both the first single-particle beams and the second single-particle beams.

41. A multiplicity particle beam system according to the preceding claim, wherein a second micro-optics system with a plurality of successively arranged multi-aperture plates is provided in the second particle-optical beam path, which are each successively penetrated by the charged second single particle beams, wherein the micro-optics system has a final multi-aperture plate with respect to the particle-optical beam path, which is magnetically conductive, wherein for a permeability p r of the material of the final multi-aperture plate the following relation applies: p r s 1000, especially p r s 10000 or p r > 15000, wherein the second particle optics comprises a magnetic projection lens, wherein the final multi-aperture plate of the second micro-optics is arranged within a magnetic field generated by the magnetic projection lens during operation of the multi-particle beam system, wherein the controller is configured to control the magnetic projection lens and to adjust its magnetic field strength, and wherein the controller is further configured such that, by means of a change in the magnetic field strength of the magnetic projection lens, an azimuthal tilt of the charged second individual particle beams is adjusted upon impingement on the detection regions and / or upon penetrating a contrast aperture arranged at the level of a beam crossing of the second individual particle beams.

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