Multi-particle beam system with extended maintenance interval

Abstract

Disclosed is a multi-particle beam system 1 with an arrangement comprising a pre-aperture module 370 and a micro-optics module 380. The pre-aperture module 370 comprises a carrier plate 371 with a first set comprising at least two identical and thus effectively identical multi-aperture arrays 372, which have the same number N of apertures, the same shape and size of the apertures, and the same arrangement of the apertures and are thus interchangeable. A mechanism for arranging the carrier plate 371 in the particle-optical beam path allows the exchange of effectively identical multi-aperture arrays in the event of damage to the active multi-aperture array, in particular due to X-rays. The micro-optics module 380 arranged downstream of the pre-aperture module 370 in the particle-optical beam path is thus better protected against X-rays and has a longer service life. Maintenance intervals of the multi-particle beam system 1 can be extended.

Description

Field of the InventionThe invention relates generally to multiple particle beam systems which operate with multiple charged single particle beams, such as multiple beam particle microscopes or lithography systems. Specifically, the invention relates to a multiplicity of particle beam systems with an extended maintenance interval.Prior ArtWith the continuous development of smaller and more complex microstructures such as semiconductor devices, there is a need to further develop and optimize planar fabrication techniques and inspection systems for fabricating and inspecting small dimensions of the microstructures. For example, the development and fabrication of the semiconductor devices requires a review of the design of test wafers, and the planar fabrication techniques require process optimization for reliable, high throughput fabrication. Moreover, recently, analysis of semiconductor wafers for reverse engineering and custom individual configuration of semiconductor devices have been demanded. There is therefore a need for inspection means that can be used with high throughput for inspecting microstructures on wafers with high accuracy.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") having a size of up to 800 mm 2. A semiconductor device includes a plurality of semiconductor structures fabricated by planar integration techniques in layers on a surface of the wafer. Due to the manufacturing processes, semiconductor wafers typically have a planar surface. The structure size of the integrated semiconductor structures extends from a few μm up to the critical dimensions (CD) of a few nanometers, wherein in the near future the structure sizes become even smaller; it is expected that the structure sizes or critical dimensions (CD) will correspond in the future to the 3 nm, 2 nm or even smaller technology nodes of the international technology schedule for semiconductors (ITRS)). In the above-mentioned small feature sizes, defects in the size of critical dimensions must be identified in a very large area in a short time. 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 width of a semiconductor feature needs to be measured with an accuracy below 1 nm, for example 0.3 nm or even less, and a relative position of semiconductor structures needs to be determined with an overlay accuracy below 1 nm, for example 0.3 nm or even less.A recent development in the charged particle microscope (CPM) field is mSEM, a multi-beam scanning electron microscope. A multi-beam scanning electron microscope is disclosed, for example, in U.S. Pat. No. 7,244,949 B2 and in U.S. Pat. No. 2019 / 0355544 A1. In a multi-beam electron microscope or mPTFE, a sample is irradiated simultaneously with a plurality of single electron beams arranged in an array or grid. For example, 4 to 10000 individual electron beams can be provided as primary radiation, wherein each individual electron beam is separated from an adjacent individual electron beam by a distance of 1 to 200 micrometers. For example, an mSEM has approximately 100 separate beamlets ("beamlets") arranged, for example, in a hexagonal grid, wherein the individual electron beams are separated by a distance of approximately 10 μm. The plurality of charged single particle beams (primary beams) are focused on a surface of a sample to be examined by a common objective lens. The sample may be, for example, a semiconductor wafer mounted on a wafer holder mounted on a movable stage. During the illumination of the wafer surface with the charged primary individual particle beams, interaction products, for example secondary electrons or back-scattered electrons, originate from the surface of the wafer. Their starting points correspond to the locations on the sample onto which the plurality of primary individual particle beams is in each case focused. The amount and energy of the interaction products depends on the material composition and the topography of the wafer surface. The interaction products form a plurality of secondary single particle beams (secondary beams) collected by the common objective lens and incident on a detector disposed in a detection plane through a projection imaging system of the multi-beam inspection system. The detector includes a plurality of detection regions each including a plurality of detection pixels, and the detector detects an intensity distribution for each of the secondary single particle beams. An image field of, for example, 100 μm×100 μm is obtained.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 the triangulation of the plurality of charged single particle beams. The prior art charged particle multi-beam system also includes at least one crossover plane of the primary or secondary charged single particle beams. Furthermore, the prior art system includes detection systems to facilitate adjustment. The multi-beam particle microscope of the prior art comprises at least one beam deflector ("deflection scanner") for collectively scanning a region of the sample surface by means of the plurality of primary single particle beams in order to obtain an image field of the sample surface.For separating the particle-optical beam path of the primary beams from the particle-optical beam path of the secondary beams, a so-called beam splitter ("beam splitter" or "beam separator" or "beam divisor") is used. Separation is effected by means of special arrangements of magnetic fields and / or electrostatic fields, for example by means of a Wien filter.In the case of a plurality of particle beam systems, a distinction is fundamentally made between systems which operate with a single column and systems which operate with a plurality of columns. In systems with a single column, the passage of the single particle beams takes place at least partially through the same particle optics or through one or more global particle lenses. In addition, in the case of a single column, the single particle beams are relatively close to one another. Despite the partially global particle-optical elements, there is a need for individual influenceability and / or formability of the individual particle beams in individual columns in order to correct aberrations such as curvature of the field, astigmatism of the field and other aberrations. For this individual influencing and / or shaping of the individual particle beams, a so-called microoptical system can be used. Micro-optics are often also referred to as multi-beam particle generators for generating and shaping a plurality of individual particle beams. The multi-beam particle generator or the micro-optics comprises a sequence of a plurality of multi-aperture plates, which can be used for active beam shaping or of which at least one multi-aperture plate can be used for active beam shaping. For this purpose, electrodes can be provided, for example, in the area of the apertures, which electrodes can be controlled collectively or individually. These may be, for example, ring electrodes or multipole electrodes. According to another example, a multi-aperture plate can be monolithically formed, wherein a voltage is applied to the multi-aperture plate overall, i.e. the monolithic multi-aperture plate is then at a specific potential, so that its openings can generate a lens effect in cooperation with other particle-optical elements. Other configurations of a multi-aperture plate for active beam shaping are also possible.For the production of micro-optics, MEMS techniques or planar integration techniques are used, for example, that is to say the same methods that are also used for semiconductor production. The production of micro-optics is relatively slow and expensive, and a single micro-optics is therefore relatively valuable.During operation of a plurality of particle beam systems, however, the microoptics are exposed to wear processes even during operation under high vacuum: a portion thereof has not only charged particles, such as electrons, impinging on the microoptics, but also secondary particles, which are ejected from the microoptics, and X-ray radiation which occurs when charged particles impinge on the microoptics. These particles and in particular the X-ray radiation impair the functioning of the microoptical unit and the microoptical unit is destroyed in the long term and has to be exchanged. This exchange, in turn, is second-time: the vacuum in the column of the multiple particle beam system must be broken and subsequently restored. In addition, necessary adjustment work on the system is required because of the replacement of the micro-optics that is carried out. An exchange of the microoptics should therefore have to be carried out as rarely as possible.U.S. Pat. No. 9,653,254 B2 discloses a multiplicity of particle beam systems which permits simple setting of a beam current of individual particle beams. To this end, a multi-aperture selector plate having a plurality of multi-aperture arrays is disclosed, which is arranged on a movable carrier. The multi-aperture arrays are all formed differently, namely with regard to the aperture diameter and / or with regard to the number of apertures per array. By arranging the multi-aperture selector plate differently in the particle-optical beam path, it is thus possible to generate a different number of individual particle beams and / or the individual beam diameter and thus the individual beam current intensity of the individual particle beams can thus be adjusted. A problem in connection with wear processes and in particular in connection with X-ray radiation is not discussed in U.S. Pat. No. 9,653,254 B2. The specific structure of a sequence of multi-aperture plates and their production will also not be described in more detail.DE 10 2020 115 183 A1 discloses a particle beam system with a multisource system. The multi-source system has an electron emitter array as a particle multi-source. In this multi-source system, the inhomogeneous emission characteristics of the various emitters are corrected by particle-optical components which can be produced by means of MEMS techniques or precorrected for a subsequent particle-optical imaging. A beam current of the individual particle beams can be adjusted in the multi-source system.DE 10 2018 202 421 B3 discloses a multi-beam particle beam system comprising a multi-aperture plate having a plurality of apertures, wherein each of the apertures is traversed in operation by a particle beam of the plurality of particle beams. A plurality of electrodes are provided insulated from the second multi-aperture plate in order to influence the particle beam passing through the aperture. A voltage supply system for the electrodes comprises a signal generator for generating a serial sequence of digital signals, a D / A converter for converting the digital signals into a sequence of voltages between an output of the D / A converter and the multi-aperture plate, and a controllable switching system for supplying the sequence of voltages to different electrodes in succession.DE 10 2018 133 703 A1 discloses an apparatus for generating a plurality of particle beams comprising a particle source, a first multi-aperture plate having a plurality of openings, a second multi-aperture plate having a plurality of openings, a first particle lens, a second particle lens, a third particle lens and a controller which supplies an adjustable excitation to the first particle lens, the second particle lens and the third particle lens, respectively.DE 10 2018 007 652 A1 discloses a particle beam system for adjusting single beam currents, comprising: at least one particle source, which is configured to generate a beam of charged particles; a first multi-lens array, which comprises a first plurality of individually adjustable and focusing particle lenses and which is arranged in the beam path of the particles such that at least some particles pass through openings of the multi-lens array in the form of a plurality of single particle beams; a second multi-aperture plate, which has a plurality of second openings and which is arranged in the beam path of the particles after the first multi-lens array and in such a way that particles which pass through the first multi-lens array partially strike the second multi-aperture plate and partially pass through the openings of the second multi-aperture plate; and a controller which is configured to supply an individually adjustable voltage to the particle lenses of the first multi-lens array and thus individually adjust the focusing of the associated particle lens for each individual particle beam.DE 10 2014 008 083 A1 discloses a particle beam system comprising a particle source; a first multi-aperture plate having a plurality of openings behind which particle beams are shaped; a second multi-aperture plate having a plurality of openings through which the particle beams pass; an aperture plate having an opening through which all particles that also pass through the openings in the first and second multi-aperture plates pass; a third multi-aperture plate having a plurality of openings through which the particle beams pass and having a plurality of field generators, each of which provides a dipole field or quadrupole field for a beam; and a controller for supplying electrical potentials to the multi-aperture plates and the aperture plate such that the second openings in the second multi-aperture plate each act as a lens on the particle beams, and supplying adjustable excitations to the field generators.DESCRIPTION OF THE INVENTIONIt is the object of the present invention to provide a multiplicity of particle beam systems with an extended maintenance interval. In particular, a micro-optics of the plurality of particle beam systems should have a longer lifetime and have to be exchanged less frequently. In particular, it is to be better protected from X-ray radiation. Optionally, an exchange of the microoptical system should be able to be carried out more quickly overall.The object of the invention is achieved by the subject matter of the independent claim. Advantageous embodiments of the invention are evident from the dependent claims.Conventional high-power micro-optics are manufactured using MEMS techniques. In addition to the beam-forming multi-aperture plates, the micro-optics also comprise a first single-beam-generating multi-aperture plate, the so-called filter plate or pre-aperture plate. Not only are the individual particle beams generated at this filter plate or pre-aperture plate when passing through the filter plate, but the impingement of high-energy charged particles on the filter plate also leads to the generation of X-ray radiation, which first damages the filter plate, but then also the remaining multi-aperture plates of the micro-optics and makes it unusable in the long term.It is therefore a basic idea of the invention to decouple the filter plate from the actual beam-forming micro-optic and to make it separately replaceable. By replacing the filter plate, the beam-forming micro-optic arranged in the particle-optical beam path downstream thereof is protected overall for longer from the damaging influences of the X-ray radiation and it has to be replaced less frequently. For this purpose, in the case of the multiplicity of particle beam system according to the invention, a modular structure is provided with a pre-aperture module on the one hand and with a micro-optics module on the other hand. The pre-aperture module in turn comprises, as a reservoir, a plurality of identical and thus functionally identical multi-aperture arrays, which can be used successively as filter arrays. In principle, an exchange of the multi-aperture arrays is possible without breaking the vacuum of the plurality of particle beam systems until the supply of multi-aperture arrays is used up.According to a first aspect of the invention, it relates to a plurality of particle beam systems, which comprises:a particle source for emitting charged particles;a pre-aperture module comprisinga carrier plate, wherein the carrier plate comprises a first set with at least two identical multi-aperture arrays, which have the same number N of apertures, the same shape and size of the apertures and the same arrangement of the apertures and are thus mutually interchangeable,a holding element for the carrier plate, anda mechanism for arranging, in particular displacing, the carrier plate in the particle-optical beam path and for exchanging the at least two identical multi-aperture arrays in the particle-optical beam path with one another,wherein, during operation of the plurality of particle beam system, the carrier plate is arranged in the particle-optical beam path of the plurality of particle beam system such that the charged particles,which are emitted by the particle source, impinge on only one of the at least two multi-aperture arrays and pass through the latter to form a plurality of first individual particle beams N; anda micro-optic module arranged in the particle-optical beam path after the pre-aperture module and comprising:a sequence of a plurality of multi-aperture plates forming the micro-optic and fixedly arranged relative to each other, anda micro-optic holder for holding the micro-optic,wherein during operation of the plurality of particle beam system the apertures of the multi-aperture plates are each traversed by exactly one of the individual particle beams, and wherein the micro-optics form the plurality of first individual particle beams in a particle-optical manner.The plurality of particle beam systems can be, for example, a multi-beam inspection system, in particular a multi-beam particle microscope. However, it can also be a lithography system or another multiplicity of particle beam systems. Preferably, this is a multiplicity of particle beam systems which operate with a single column.The plurality of particle beam systems has at least one particle source for emitting charged particles, for example electrons, positrons, myones or ions.The carrier plate with the at least two identical multi-aperture arrays forms the frog of the pre-aperture module. A multi-aperture array takes over the function of the filter plate in each case, as described above in connection with the description of the prior art. By means of the multi-aperture array, which is currently arranged in the particle-optical beam path, the plurality of first individual particle beams is thus generated. The carrier plate with the respectively active multi-aperture array, that is to say with the multi-aperture array respectively arranged in the particle-optical beam path, is preferably the first multi-aperture unit calculated by the particle source or first multi-aperture plate which is used for forming the first individual particle beams. This has the consequence that the charged particles impinging on the multi-aperture array impinge there in a very large number. According to a preferred embodiment of the invention, more than 90% of all particles impinging on the multi-aperture array are absorbed and discharged there; according to another preferred embodiment variant, more than 95% or more than 98% of the charged particles are. During this impact of the particles on the multi-aperture array, secondary particles are ejected from the carrier plate there and X-ray radiation is produced. Both lead to damage to the carrier plate and also to structures arranged beneath it. The damage to structures arranged beneath it is all the greater the greater the damage to the carrier plate or the damage in the active multi-aperture array. By exchanging the multi-aperture array in the particle-optical beam path, the lifetime of the pre-aperture module and thus also its protective function for the underlying actual micro-optic or the micro-optic module can be extended. The microoptical module therefore does not have to be exchanged as frequently. This is more durable and saves time and costs.The mechanism for arranging the carrier plate in the particle-optical beam path can be realized in different ways. It can be formed in one part or in multiple parts. It is possible for the mechanism to be operated manually. The mechanism can preferably be electronically controlled. This allows a more precise positioning of the carrier plate with the identical multi-aperture arrays located thereon in the particle-optical beam path.The term "arranging" in connection with the present patent application is merely understood to mean that one of the identical multi-aperture arrays can be introduced into the particle-optical beam path in a targeted manner. This can be a displacement of the carrier plate, but it can also be a rotation of the carrier plate etc. The term of exchanging two identical multi-aperture arrays in the particle-optical beam path with one another only means that the two multi-aperture arrays are functionally exchanged: one multi-aperture array is active and the other is not. It does not automatically mean that the positions of the two multi-aperture arrays are exchanged exactly with one another.The micro-optics module according to the present invention comprises a sequence of a plurality of multi-aperture plates forming the (beam forming) micro-optics and which are fixed relative to each other. This fixed arrangement defines the module-like character of the micro-optic module. It is not possible by definition that one of the multi-aperture plates of the micro-optics module can be exchanged separately during operation or a short operating pause of the plurality of particle beam systems. Instead, it is the case that the sequence of a plurality of multi-aperture plates or the microoptics is produced as a module before the installation into the multiplicity of particle beam systems.According to the invention, the microoptics form the multiplicity of first individual particle beams in a particle-optical manner. The microoptics is thus an active microoptics, that is to say the particle-optical beam path of the first individual particle beams is actively influenced by the microoptics. The individual particle beams can be focused, deflected, provided with a triangulation or the like, for example. Particle-optical shaping by means of the micro-optics does not mean, however, generating the first individual particle beams. Instead, this is done by means of the pre-aperture module and the multi-aperture arrays arranged in the carrier plate.According to a preferred embodiment of the invention, the microoptics comprise a multi-stigmator unit and / or the microoptics comprise a multi-lens array. The multi-locator unit can be realized, for example, as a multi-aperture plate, wherein individually controllable multipole electrodes are provided in the region of the apertures. The multi-lens array can be realized, for example, as a multi-aperture plate, ring electrodes being provided around the openings thereof. However, other realization forms for these active elements of the microoptics for particle-optical beam forming are also possible.According to a preferred embodiment of the invention, the sequence of the multi-aperture plates has a first multi-aperture plate through which the first individual particle beams formed in the pre-aperture module pass in the particle-optical beam path of the plurality of particle beam systems as the first multi-aperture plate. In this case, the dimensions of the apertures of the first multi-aperture plate are designed such that the first individual particle beams pass through the apertures of the first multi-aperture plate without contact. The first multi-aperture plate of the micro-optics is thus functionally not a filter plate. Because the first individual particle beams pass through the apertures of the first multi-aperture plate in a contactless manner, charged particles do not strike this first multi-aperture plate and do not form secondary particles or X-ray radiation. This protects the micro-optic from contamination and destruction by this secondary particle / secondary radiation.According to a preferred embodiment of the invention, the holding element of the carrier plate is firmly connected to the micro-optics holder of the micro-optics or integrated therein. This provides a fixed reference in the relative positioning of the pre-aperture module relative to the micro-optics module. These must be aligned exactly with respect to one another in order to be able to cooperate functionally exactly. For example, the centers of apertures of a multi-aperture array in the support plate would have to be exactly aligned with the centers of apertures in the sequence of multi-aperture plates of the micro-optics.According to a preferred embodiment of the invention, the micro-optics holder has a flange by means of which the micro-optics holder is sealingly installed in the plurality of particle beam systems. During operation, a vacuum or high vacuum normally prevails in the multiplicity of particle beam systems. The sealing installation of the microoptics by means of the microoptics holder is therefore then important. This can be easily realized by means of a flange.According to a preferred embodiment of the invention, the holding element of the carrier plate is passed through the flange. Preferably, the holding element of the carrier plate is also mounted in the flange as a result. In addition, it is preferably such that this passage is formed in a vacuum-tight manner. In this embodiment, the holding element of the carrier plate is therefore integrated into the micro-optic holder or the flange.According to a preferred embodiment of the invention, the pre-aperture module further comprises a lower aperture plate having a singular central opening, which is arranged in the particle-optical beam path between the carrier plate and the micro-optics module such that during operation of the plurality of particle beam systems the first individual particle beams pass through the opening of the lower aperture plate in a contactless manner. According to the invention, this lower aperture plate serves, inter alia, as a shielding plate: secondary particles and X-ray radiation which are generated when the charged particles of the particle source strike the active multi-aperture array normally have different directions or scattering angles. A large part of the secondary particles or X-ray radiation generated, which has a directional component in the direction of the microoptics module, can thus strike this lower aperture plate. This further protects the microoptics of the microoptics module. Contactless passage of the lower aperture plate is important for two reasons: on the one hand, the first individual particle beams have already been generated in principle in the pre-aperture module. Cutting out or attenuating some individual particle beams is therefore counterproductive. Secondly, non-contactless impingement on the lower aperture plate would in turn ensure that secondary particles and X-ray radiation are produced, which in turn would negatively impair the service life of the microoptical system.According to a preferred embodiment of the invention, the material of the lower aperture plate is X-ray absorbing. Preferably, it comprises copper. The lower aperture plate is preferably about 1 mm to 1.5 mm thick. Additionally or alternatively, it is possible for the lower aperture plate to be coated so as to absorb X-rays. Such a coating can comprise, for example, a gold coating, for the thickness d AU for example 3 μm≤d AU≤50 μm, preferably 5 μm≤d AU≤20 μm. The gold coating can be applied by sputtering or galvanically. Additionally or alternatively, it is also possible for the X-ray absorbing layer to have a thin film or layer comprising copper, tantalum and / or titanium, wherein for the thickness d S of this layer, for example, 0.1 mm≤d S≤1.0 mm, preferably 0.25 mm≤d S≤0.75 mm applies.According to a preferred embodiment of the invention, the following relationship applies for a distance D 2 between the lower aperture plate and an uppermost multi-aperture plate of the microoptics module: D 2≥0.5 cm, preferably D 2≥1.0 cm or D 2≥5.0 cm. The uppermost multi-aperture plate can be identical to the first multi-aperture plate of the micro-optics. The distance D 2 between the lower aperture plate of the pre-aperture module on the one hand and the uppermost multi-aperture plate of the micro-optics module on the other hand is a measure of the distance between the pre-aperture module and the micro-optics module. This distance can be selected to be greater than in a nonmodular embodiment of single beam generation and single beam formation, on the one hand, due to the modular division for single beam formation and particle-optical shaping of the single particle beams, on the other hand. The plurality of particle beam systems according to the invention thereby has a flexibly selectable parameter more than conventional plurality of particle beam systems. A relatively large distance D 2 also has the consequence that the shielding effect or protective effect of the pre-aperture module for the micro-optics module is improved even further. Namely, at a larger distance D2, even more secondary particles and even more X-ray can be prevented from reaching the micro optic itself.According to a preferred embodiment of the invention, the pre-aperture module further comprises an upper aperture plate having a singular central opening, which is arranged in the particle-optical beam path above the carrier plate such that the charged particles of the particle source partially or completely pass through the central opening of the upper aperture plate. Unlike the lower aperture plate, the upper aperture plate is not per se harmful to the micro-optic located further down in the particle-optical path when secondary particles and X-rays are generated at the upper aperture plate. The upper aperture plate is somewhat farther from the micro-optic than the lower aperture plate of the pre-aperture module. However, it is also possible for the charged particles of the particle source to pass through the central opening of the upper aperture plate completely and thus without contact, without secondary particles or X-ray radiation being produced.According to a preferred embodiment of the invention, the material of the upper aperture plate is X-ray absorbing. Preferably, it comprises copper. Preferably, the thickness of the upper aperture plate is at least 1 mm. Additionally or alternatively, it is possible for the upper aperture plate to be coated in an X-ray absorbing manner. Such a coating can comprise, for example, a gold coating, for the thickness d AU for example 3 μm≤d AU≤50 μm, preferably 5 μm≤d AU≤20 μm. The gold coating can be applied by sputtering or galvanically. Additionally or alternatively, it is also possible for the X-ray absorbing layer to have a thin film or layer comprising copper, tantalum and / or titanium, wherein for the thickness d S of this layer, for example, 0.1 mm≤d S≤1.0 mm, preferably 0.25 mm≤d S≤0.75 mm applies.According to a preferred embodiment of the invention, the upper aperture plate and the lower aperture plate form walls of a pre-aperture chamber for the carrier plate and the opening in the upper aperture plate and / or the lower aperture plate is / are closable in a vacuum-tight manner. For this purpose, a vacuum slide can be provided, for example, in the region of the singular openings of the upper and lower aperture plate. As a result, the pre-aperture chamber can be closed in a vacuum-tight manner in both directions, that is to say specifically both in the direction of the particle source and in the direction of the microoptical system. If the carrier plate with the at least two identical multi-aperture arrays namely has arrived at the end of its lifetime, i.e. all identical multi-aperture arrays are damaged, the carrier plate must be replaced. In the described embodiment variant, it is now possible to initially close the pre-aperture chamber in a vacuum-tight manner in the particle-optical beam path and subsequently to break the vacuum only in the pre-aperture chamber. The carrier plate can then be removed from the pre-aperture chamber and exchanged for a new carrier plate with new identical multi-aperture arrays. It is furthermore possible to evacuate and / or heat the pre-aperture chamber again. Thereafter, the openings of the upper aperture plate and / or the lower aperture plate can be released again. An exchange of the carrier plate carried out in this way takes place more quickly than an exchange of the entire pre-aperture module or even an exchange of the entire micro-optic module. In addition, this procedure is more resource-saving.According to a preferred embodiment of the invention, the pre-aperture chamber is accessible from outside the plurality of particle beam systems. This facilitates the above-described replacement of the carrier plate without having to replace the entire pre-aperture module.According to a preferred embodiment of the invention, the carrier plate is linearly displaceable in a direction orthogonal to the particle-optical beam path. The carrier plate can thus be displaced, for example, from left to right.According to a further preferred embodiment of the invention, the carrier plate is displaceable with two degrees of freedom within a plane which is oriented orthogonally to the particle-optical beam path. According to one example, the carrier plate is therefore not only displaceable from left to right, but also, for example, from front to rear (x- and y-direction if the particle-optical beam path corresponds to the z-direction).According to a preferred embodiment of the invention, the carrier plate is displaceable along the direction of the particle-optical beam path. The carrier plate thus comprises a height adjustment along the particle-optical beam path. This is an additional degree of freedom, which makes it possible, for example, to use the pre-aperture module according to the invention in combination with a multiplicity of differently configured micro-optics modules.According to a preferred embodiment of the invention, the multi-aperture arrays of the carrier plate can be introduced into the particle-optical beam path by means of a carousel or revolver system. In this embodiment variant of the invention, too, the exchangeability of functionally identical multi-aperture arrays is made possible.According to a preferred embodiment of the invention, the apertures of the two functionally identical multi-aperture arrays are round or elliptical. Additionally or alternatively, the apertures of the two multi-aperture arrays have a field profile. In this case, for example, the radii of round apertures in the multi-aperture arrays are not all of identical size. For example, the radius of the apertures can depend on how far the aperture is from the middle of the individual particle beams (radial dependence). The same can apply to the ellipticity of the apertures. However, it is also possible for the described field profile to be graphical, for example to vary from left to right and / or to vary from front to rear.According to a preferred embodiment of the invention, the carrier plate has at least one second set with at least two identical multi-aperture arrays. In this second set, the at least two identical multi-aperture arrays are in turn functionally identical, that is to say the number of apertures is identical, the shape of the apertures and the size of the apertures are identical and the apertures have overall the same arrangement in the multi-aperture arrays. According to the invention, the apertures of the multi-aperture arrays of the first set differ from the apertures of the multi-aperture arrays of the second set. The first set of the carrier plate can differ from the second set of the carrier plate, for example, by the radius of the apertures. In this way, it is possible not only to extend the lifetime of the micro-optics of the multiplicity of particle beam systems, but also to vary the beam current intensity of the individual particle beams: in the case of large apertures, this beam current intensity is large, in the case of small apertures it is small. In addition, it is possible, for example, for the first set to be provided with round apertures in the multi-aperture arrays and for the second set to be provided with elliptical apertures in the multi-aperture arrays. Other design variants are also possible.In addition, the carrier plate can have a third or further set with likewise at least two functionally identical multi-aperture arrays. However, it is not advisable to provide too many sets in the carrier plate. This is because there is the risk that not every set is actually completely used or used up until the end of the service life of the carrier plate.According to a preferred embodiment of the invention, the plurality of particle beam systems furthermore has at least one further microoptics module which is arranged within a vacuum but outside the particle-optical beam path of the plurality of particle beam systems. Furthermore, the plurality of particle beam systems has an exchange mechanism for exchanging the microoptics module with the further microoptics module under vacuum. In this embodiment variant of the invention, the further microoptics module is thus already provided, so to speak, for storage under vacuum in the multiplicity of particle beam systems. If the exchange of the micro-optics module for the further micro-optics module is necessary, this can be done more quickly, because a vacuum break in the multiple particle beam system is not necessary for this.According to a further preferred embodiment of the invention, the plurality of particle beam systems has a storage chamber in which the at least one further microoptics module is arranged. In this case, the storage chamber is separated from the internal vacuum of the multiplicity of particle beam systems by means of a lock. This lock protects the further micro-optics even better from X-ray radiation and in particular also from secondary radiation which arises in the interior of the plurality of particle beam systems. The active microoptics module can be exchanged for the further microoptics module through the lock.According to a further preferred embodiment of the invention, the storage chamber has an outer door and / or the storage chamber has a vacuum and ventilation unit in order to build up a vacuum in the storage chamber or to ventilate the storage chamber. A defective or used microoptics module can be removed through this outer door during the operation of the multiplicity of particle beam systems and a new, unused microoptics module can be introduced into the storage chamber. This does not interfere with the ongoing operation of the multiplicity of particle beam systems. During the operation of the plurality of particle beam systems, a vacuum can then furthermore be built up in the storage chamber by means of the vacuum and ventilation unit. In this way, an unused micro-optics module is more quickly ready for exchange under vacuum in the plurality of particle beam systems.According to a preferred embodiment of the invention, the storage chamber furthermore has a heating element for heating out the storage chamber and / or the storage chamber has a plasma cleaning unit in order to clean a stored microoptics module and / or an exchanged microoptics module. The heating element allows a vacuum or high vacuum to be established more quickly in the storage chamber. The plasma cleaning unit reduces the introduction of contaminants at a micro-optics module into the particle-optical beam path of the plurality of particle beam systems. In addition, it is possible that an already exchanged microoptics module can be once again put into a state in which it can be used without errors in the multiplicity of particle beam systems for some time by the plasma cleaning unit.It is of course also possible not only to exchange the microoptics module in the described manner, but to exchange the combination of the pre-aperture module and the microoptics module in the described manner. Depending on the structural configuration of the pre-aperture module and micro-optics module, this may be preferred or even necessary for an exchange. In addition, it is possible to also exchange a microoptics including a filter plate already known from the prior art in this way. This would then be less lasting overall, however, for which reason the modular construction with the pre-aperture module and micro-optics module is preferred for the individual particle beam formation and shaping.The invention will be better understood with reference to the accompanying figures. The following are shown: FIG. 1 shows schematically a multiplicity of particle beam systems; FIG. 2 shows schematically a structure of a microoptics with a filter plate; FIG. 3 shows schematically an arrangement with a pre-aperture module and with a micro-optics module; FIG. 4 shows schematically an arrangement with a pre-aperture module and with a micro-optics module; FIG. 5 schematically shows a plurality of carrier plates with multi-aperture arrays; FIG. 6 shows schematically a plurality of carrier plates with multi-aperture arrays; FIG. 7 shows schematically a carrier plate with multi-aperture arrays; FIG. 8 shows schematically an arrangement with a pre-aperture module and with a micro-optics module; FIG. 9 : shows schematically a multiplicity of particle beam systems having a storage chamber for a microoptics module; and FIG. 10 : shows schematically a multiplicity of particle beam systems having a storage chamber for a microoptics moduleFIG. 1 schematically shows a plurality of particle beam systems 1 in the form of a multi-beam particle microscope 1. 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. The multi-aperture arrangement 305 comprises a plurality of multi-aperture plates 306 and a field lens 308. A plurality of individual particle beams 3 or individual electron beams 3 is generated by the multi-aperture arrangement 305. Centers of apertures of the multi-aperture plate arrangement are arranged in a field which is imaged onto a further field which is formed by beam spots 5 in the object plane 101. The distance between centers of apertures of a multi-aperture plate 306 may be, for example, 5 μm, 100 μm and 200 μm. The diameters D of the apertures are smaller than the pitch of the centers of the apertures, examples of the diameters are 0.2 times, 0.4 times and 0.8 times the pitches between the centers of the apertures.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 raster arrangement in a surface 321. The surface 321 may not be a planar surface but may be a spherically curved surface to keep a field curvature of the subsequent particle optical system.The multi-beam particle microscope 1 further comprises a system of electromagnetic lenses 103 and an objective lens 102 which image the beam focus 323 in a reduced manner from the intermediate image surface 325 into the object plane 101. The first individual particle beams 3 pass between the beam splitter 400 and a collective beam deflection system 500, with which the plurality of first individual particle beams 3 is deflected during operation and the image field is scanned. The first individual particle beams 3 impinging into the object plane 101 form, for example, an essentially regular field, wherein distances between adjacent impingement locations 5 can be, for example, 1 μm, 10 μm or 40 μm. The field formed by the impingement locations 5 can have, for example, a rectangular or a hexagonal symmetry.The object to be inspected 7 may be of any kind, for example, a semiconductor wafer or a biological sample, and may include 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 may include one or more electron optical lenses. It can be, for example, a magnetic objective lens and / or an electrostatic objective lens.The primary particles 3 striking the object 7 generate interaction products such as secondary electrons, back-scattered electrons or primary particles which have undergone a movement reversal for other reasons, which originate 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 shaped by the objective lens 102 into secondary particle beams 9. In this case, the secondary beams 9 downstream of the objective lens 102 pass through the beam splitter 400 and are fed to a projection system 200. The projection system 200 comprises an imaging system 205 having projection lenses 208, 209 and 210, a contrast aperture 214 and a multi-particle detector 207. Sites of impingement 25 of the second individual particle beams 9 on detection regions of the multi-particle detector 207 are situated in a third field at a regular distance from one another. Exemplary values are 10 μm, 100 μm, and 200 μm.The multi-beam particle microscope 1 furthermore has a computer system or a control unit 10, which in turn can be embodied in one part or in multiple parts, and which is embodied both for controlling the individual particle-optical components of the multi-beam particle microscope 1 and for evaluating and analyzing the signals obtained with the multi-detector 207 or the detection unit.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 plate 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 / 06017 A 2 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.The multi-aperture arrangement 305 comprises a plurality of multi-aperture plates for generating the individual particle beams 3 and for particle-optical shaping of the plurality of particle beams.In this case, the multi-aperture arrangement 305 can be of modular construction and comprise an arrangement according to the invention having a pre-aperture module 370 and a micro-optics module, as described above in a plurality of embodiment variants.FIG. 2 shows, by way of example, a microoptical unit 305 which is designed as a multi-beam generator 305. In the example shown, the multi-beam generator 305 comprises, in the z-direction, which corresponds to the propagation direction of the individual particle beams 3, a sequence having six multi-aperture plates 304, 306.1, 306.2, 306.3, 306.4 and 310 and 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 through which the plurality of individual particle beams 3 pass, respectively. The cross-section through the apertures 351 in FIG. 2 is not true to scale.The plurality of multi-aperture plates 304, 306.1, 306.2, 306.3, 306.4 and 310 are spaced apart 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. By the impingement of a collimated particle beam or electron beam 309, the plurality of first individual particle beams 3 is generated during the passage through the first multi-aperture plate 304, which is also called a filter plate or a pre-aperture plate. The pre-aperture plate 304 comprises a metallic layer 99 on its beam input side for stopping and absorbing the charged particles or 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. of doped silicon, and is at ground potential.The next multi-aperture plate in the example shown in FIG. 2 is a multi-stigmator plate 306.1. 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 the 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 and thereby individually influence each individual particle beam 3. It is possible, for example, to deflect each individual particle beam 3 in each direction up to a few μm with an antisymmetrical voltage difference in order to precorrect a distortion of the illuminating unit 100. An astigmatism precorrection of each individual particle beam 3 can thus be carried out. With an offset voltage, each multipole element can additionally function as a single lens.The multi-aperture plates 306.2, 306.3 and 306.4 can in principle be any desired trajectory correction plates which are monolithically formed and to which a voltage V 1, V 2 or V 3 is applied in each case in the example shown. 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 in design, for example have different diameters, in order to take account of a field dependence of the correction in the course correction of the individual particle beams 3.The multi-aperture plate 310 is a two-layered 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 individual particle beam 3 passing through it. The upper layer is insulated from the layer having the ring electrodes 79 and 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 can be applied, e.g., 12 kV to 17 kV. In the example shown, the condenser lens 307 provides a global electrostatic lens field for global focusing of the plurality of individual particle beams 3.The micro-optics 305 illustrated in FIG. 2 or their multi-aperture plates can / can be produced in principle by means of known production methods or by means of planar integration techniques. In this case, it is characteristic of the microoptics 305 that the microoptics 305 comprise the filter plate 304, such that the multiplicity of first individual particle beams 3 is generated at all by means of the microoptics 305. However, the impingement of charged particles such as electrons on the filter plate 304 not only generates the first individual particle beams 3, but also generates X-ray radiation which, on the one hand, damage the filter plate 304 itself and, on the other hand, also damage the remaining multi-aperture plates 306.1, 306.2, 306.3, 306.4 and 310 of the micro-optics 305 and the conductor tracks / electrodes arranged thereon and, over time, make them unusable. In such a case, the entire micro-optics 305 illustrated in FIG. 2 must be exchanged during maintenance of the plurality of particle beam systems.FIG. 3 illustrates, on the basis of a first exemplary embodiment, an improved arrangement for generating the individual particle beams 3 and for the particle-optical shaping thereof: the arrangement schematically illustrated in FIG. 3 comprises a pre-aperture module 370 and a micro-optics module 380. The pre-aperture module 370 comprises a support plate 371, wherein the support plate 371 comprises a set of three identical multi-aperture arrays 372 a, 372 band 372 c. The three multi-aperture arrays 372 a, 372 band 372 care functionally interchangeable and functionally equivalent. That is, the multi-aperture arrays 372 a, 372 b, and 372 chave the same number N of apertures, the same shape and size of the apertures, and the same arrangement of the apertures. Their effect for shaping the first individual particle beams 3 is thus identical. The carrier plate 371 can be arranged or displaced in various ways in the particle-optical beam path. This is illustrated by the double arrow in FIG. 3A. The carrier plate 371 is thus arranged in the particle-optical beam path of the plurality of particle beam systems 1 during operation of the plurality of particle beam systems 1 in such a way that the charged particles-illustrated by the particle beam 309-emitted by the particle source 301 (not illustrated) impinge on only one of the three multi-aperture arrays 372 a, 372 band 372 cand pass through it to form a plurality of first individual particle beams 3.The microoptics module 380 is arranged in the particle-optical beam path downstream of the pre-aperture module 370. This has a sequence of a plurality of multi-aperture plates which form the micro-optics and which are fixedly arranged relative to one another. The sequence of multi-aperture plates is not shown in detail in FIG. 3, but instead this sequence is illustrated only as a block with a membrane region 335 and a holding region 333. During operation of the plurality of particle beam system, exactly one of the individual particle beams 3 passes through the apertures of the multi-aperture plates of the microoptical module 380, so that the microoptical particle-optically shapes the plurality of first individual particle beams 3. For example, the sequence of the multi-aperture plates can be the sequence of multi-aperture plates 306.1, 306.2, 306.3, 306.4 and 310, which was explained by way of example in FIG. 2. However, this sequence does not include a filter plate 304. According to one embodiment, the microoptics comprise a multi-stigmator unit and / or the microoptics comprise a multi-lens array.When the charged particles of the particle beam 309 strike the respectively active multi-aperture array 372 a, 372 bor 372 c, which is located in the particle-optical beam path, secondary particles are formed on the one hand and X-ray radiation is formed on the other hand. These secondary particles and in particular the X-ray radiation damage the active multi-aperture array 372 first and to a certain extent also the multi-aperture plate sequence of the micro-optics module 380. If, in the arrangement according to the invention of pre-aperture module 370 and micro-optics module 380, the damage to the active multi-aperture array 372 a, 372 band 372 cis now so far advanced that the multi-aperture array 372 a, 372 b, 372 cmay no longer be used for particle beam generation, this must be exchanged. According to the invention, this exchange is now accomplished by introducing an identical multi-aperture array 372 a, 372 band 372 cinto the particle-optical beam path by a modified arrangement of the carrier plate 371: in FIG. 3A, the multi-aperture array 372 bis active. If this has to be exchanged, the carrier plate 371 can be displaced in such a way that instead of the multi-aperture array 372 b, the still unused multi-aperture array 372 ais introduced into the particle-optical beam path. In this way, the underlying micro-optic module 380 may be protected for longer. In the course of the replacement of the defective multi-aperture array 372 b, it is also not necessary to replace the micro-optics module 380 as well. If the carrier plate comprises three identical multi-aperture arrays 372 a, 372 band 372 c, the time until the entire arrangement of the pre-aperture module 370 and the micro-optics module 380 is replaced can be approximately tripled. The more structurally identical or functionally identical multi-aperture arrays 372 are integrated into the carrier plate 371, the greater the time interval between two maintenance operations can become due to the exchange of components of the arrangement with the pre-aperture module 370 and the micro-optics module 380.In the exemplary embodiment shown in FIG. 3, the microoptics are held by means of a microoptics holder 382. The micro-optic holder 382 may include a flange, for example. The membrane region 335 corresponds to the micro-optic in the narrower sense. The beam shaping of the already previously formed first individual particle beams 3 takes place by means of the membrane region 335. In the exemplary embodiment shown, the microoptics holder 382 has a feedthrough 383 through which the carrier plate 371 of the preliminary aperture module 370 is passed. In the region of this feedthrough 383, the micro-optic holder 382 thus simultaneously also serves as a holding element for the carrier plate 371.The mechanism for arranging the carrier plate 371 in the particle-optical beam path is not explicitly illustrated in FIG. 3. Instead, only the linear direction of movement is indicated by the double arrow in FIG. 3A. The mechanism can be, for example, a linear drive which can be electrically actuated, for example. However, other embodiments are also possible.In the exemplary embodiment illustrated in FIG. 3, it is furthermore such that the sequence of multi-aperture plates of the micro-optics 335 has a first multi-aperture plate (not designated separately), through which the first individual particle beams 3 formed in the pre-aperture module 370 pass in the particle-optical beam path of the multiplicity of particle beam systems 1 as a first multi-aperture plate. The dimensions of the apertures of this first multi-aperture plate are designed such that the first individual particle beams 3 pass through the apertures of the first multi-aperture plate without contact. Therefore, there is no impact of charged first individual particle beams 3 on the first or uppermost multi-aperture plate of the micro-optics 335. There is therefore no formation of secondary particles and in particular no formation of X-ray radiation. The formation of x-ray radiation is thereby limited to another location, namely in the region of the pre-aperture module 370. This protects the micro-optic 335. In addition, the support plate 371 is spaced apart from the uppermost multi-aperture plate of the micro-optics 335 by the distance D 1. This can be, for example, more than 0.5 cm or more than 1 cm or 3 cm or 5 cm. The distance D1 can in principle be selected constructively and optionally also explicitly set. This greater distance also allows greater protection of the micro-optics 335 of the micro-optics module 380 to be achieved.In the exemplary embodiment shown in FIG. 3, the holding element of the carrier plate 371 is furthermore fixedly connected to the micro-optics holder 382 of the micro-optics 335 and, in the case shown, is integrated into the micro-optics holder 382. Specifically, the holding element of the carrier plate 371 is passed through the flange, by means of which the micro-optics holder 382 can be installed sealingly in a multiplicity of particle beam systems 1.FIG. 4 schematically shows a further arrangement with a pre-aperture module 370 and with a micro-optics module 380. In FIG. 4A, the illustrated pre-aperture module 370 further includes a lower aperture plate 373 having a singular central opening 374. This is arranged in the particle-optical beam path between the carrier plate 371 and the micro-optics module 380 in such a way that, during operation of the plurality of particle beam systems 1, the first individual particle beams 3 pass through the opening 374 of the lower aperture plate 373 in a contactless manner. In this case, in the example shown, the material of the lower aperture plate 373 is X-ray-absorbing. It can comprise copper, for example. The lower aperture plate 373 thus forms an additional protection against X-ray radiation for the microoptics module 380. The lower aperture plate is preferably about 1.0 mm to 1.5 mm thick. Additionally or alternatively, it is possible for the lower aperture plate to be coated so as to absorb X-rays. Such a coating can comprise, for example, a gold coating, for the thickness d AU for example 3 μm≤d AU≤50 μm, preferably 5 μm≤d AU≤20 μm. The gold coating can be applied by sputtering or galvanically. Additionally or alternatively, it is also possible for the X-ray absorbing layer to have a thin film or layer comprising copper, tantalum and / or titanium, wherein for the thickness d S of this layer, for example, 0.1 mm≤d S≤1.0 mm, preferably 0.25 mm≤d S≤0.75 mm applies.The arrangement shown in FIG. 4 b, comprising the pre-aperture module 370 and the micro-optics module 380, comprises, in addition to the lower aperture plate 373, an upper aperture plate 375 having a singular central opening 376. This upper aperture plate 375 is arranged in the particle-optical beam path above the carrier plate 371, such that the charged particles 309 of the particle source 301 partially or completely pass through the central opening 376 of the upper aperture plate 375. In the example shown, they completely penetrate them. Secondary beams and in particular X-ray radiation therefore also arise in the example in FIG. 4 bwhen the illuminating beam 309 impinges on the multi-aperture array 372 b. According to one embodiment of the invention, the material of the upper aperture plate 375 is X-ray absorbing. It can comprise copper, for example. Preferably, the thickness of the upper aperture plate is at least 1 mm. Additionally or alternatively, it is possible for the upper aperture plate to be coated in an X-ray absorbing manner. Such a coating can comprise, for example, a gold coating, for the thickness d AU for example 3 μm≤d AU≤50 μm, preferably 5 μm≤d AU≤20 μm. The gold coating can be applied by sputtering or galvanically. Additionally or alternatively, it is also possible for the X-ray absorbing layer to have a thin film or layer comprising copper, tantalum and / or titanium, wherein for the thickness d S of this layer, for example, 0.1 mm≤d S≤1.0 mm, preferably 0.25 mm≤d S≤0.75 mm applies.As already explained in connection with the exemplary embodiments in FIGS. 3 aand b, the carrier plate 371 is also displaceable in the particle-optical beam path in the exemplary embodiments illustrated in FIGS. 4 aand b, so that exactly one multi-aperture array 372 of the carrier plate 371 is actively arranged in the particle-optical beam path and serves as a filter array. This movement is again illustrated by the double arrows in FIGS. 4 aand 4 b.It can be seen in particular in FIG. 4 a that the upper aperture plate 375 and the lower aperture plate 373 form walls of a pre-aperture chamber 398. In this pre-aperture chamber 398, secondary particles are largely absorbed. X-ray radiation which also arises is predominantly absorbed by the walls of this pre-aperture chamber 398. The inner wall regions on the sides of the pre-aperture chamber 398 can also be X-ray absorbing for this purpose or have a corresponding coating.According to a preferred embodiment of the invention, the openings 376 and 374 of the upper aperture plate 375 and / or of the lower aperture plate 373 can be closed in a vacuum-tight manner, for example by means of a vacuum slide (not illustrated in FIG. 4 ). This can provide advantages in the exchange of the carrier plate 371, provided that the pre-aperture chamber 398 is accessible from outside the plurality of particle beam systems 1. It is then possible to close the pre-aperture chamber and then to ventilate it, to remove the carrier plate 371 completely and to replace it with a new carrier plate having a set of at least two identical multi-aperture arrays 372, to evacuate the pre-aperture chamber 398 again and to place precisely one of the functionally identical or identical multi-aperture arrays 372 of the new carrier plate 371 in the particle-optical beam path in a targeted manner. In this way, an exchange of the microoptics module 380 can be delayed even longer.FIG. 8 exemplarily shows such an example in which the pre-aperture chamber 398 comprises an outer region 385 that is accessible from the outside. After the openings 376 and 374 have been sealed, the carrier plate 371 can be reached and replaced separately by releasing the fastening region 384.The exemplary embodiments illustrated in FIGS. 3, 4 and 8 show a carrier plate 371 which is linearly displaceable in a direction orthogonal to the particle-optical beam path. However, it is of course also possible for the carrier plate 371 to be displaceable with two degrees of freedom within a plane which is oriented orthogonally to the particle-optical beam path. In addition, it is an option that the support plate 371 is displaceable along the direction of the particle optical path (height adjustment). The latter facilitates use of the pre-aperture module 370 with any micro-optics modules 380.FIG. 5 schematically shows several examples of carrier plates 371: FIG. 5 ashows a carrier plate 371 with a set comprising four identical multi-aperture arrays 372 a, 372 b, 372 cand 372 d. Each multi-aperture array 372 comprises the same number N of apertures 377 (in the example shown 16 apertures), which have the same shape and size of the apertures 377 and the same arrangement of the apertures 377. In the example shown, the apertures 377 are round and the 16 apertures 377 are arranged overall as a square array 372. Of course, the array 372 could also be arranged differently, for example as a rectangle, or it could be a hexagonal arrangement of apertures.FIG. 5 bshows a carrier plate 371 with a first set and with a second set. The first set includes multi-aperture arrays 372 aand 372 b. These are identical and have the same effect. The second set includes multi-aperture arrays 372 cand 372 d. The number of apertures, the shape and the arrangement of the apertures are identical in both sets. However, the aperture diameters differ in the two sets: the apertures 377 of the first multi-aperture arrays 372 aand 372 bhave a larger diameter than the apertures 378 of the multi-aperture arrays 372 cand 372 dof the second set. Multi-aperture arrays from different sets are therefore not functionally identical. Specifically, when using a multi-aperture array 372 a, 372 bof the first set, individual particle beams 3 having a larger individual beam diameter and thus also having a higher individual beam current are generated. Accordingly, when using the multi-aperture arrays 372 c, 372 d, individual particle beams 3 having a smaller diameter and a lower beam current intensity are generated in each case. Thus, by using a filter plate 371 with different sets of identical multi-aperture arrays 372, it can be achieved that, on the one hand, the maintenance interval is extended due to a required exchange due to x-ray damage and, on the other hand, it can be achieved that a simple possibility exists for setting different beam currents in the plurality of particle beam systems 1.FIG. 5 bshows a further filter plate 371 comprising a set with three identical multi-aperture arrays 372 a, 372 band 372 c. In the example shown, the apertures of the multi-aperture arrays 372 a, 372 band 372 ceach have an (identical) field profile. In the example shown, the aperture diameter is varied, namely in two mutually independent directions x and y or with a radial dependence on the minimum central opening in the multi-aperture arrays 372 a, 372 band 372 c. However, it is of course also conceivable for a field profile to be Cartesian and to exist only in one direction, for example for the correction of an image plane tilt.FIG. 6 schematically shows further examples of carrier plates 371: FIG. 6 ashows a carrier plate 371 with a set comprising four identical multi-aperture arrays 372 ato 372 d. In the example shown, the apertures 379 are elliptical.FIG. 6 bshows a carrier plate 371 having a total of 12 multi-aperture arrays 372 ato 372 l. Unlike in the exemplary embodiments described hitherto, these are not all arranged linearly one behind the other, but are arranged two-dimensionally or two-dimensionally in the carrier plate 371. In order to use these multi-aperture arrays 372 ato 372 l, it is therefore necessary for the carrier plate 371 of the pre-aperture module 370 to be displaceable in two linearly independent directions x, y, which are arranged orthogonally to the particle-optical beam path. In the case of such a two-dimensional arrangement of multi-aperture arrays 372, it is of course also possible to provide different sets. For each set, it applies here that it comprises at least two identical and functionally identical multi-aperture arrays 372.FIG. 7 schematically shows a further carrier plate 371 with identical multi-aperture arrays 372 ato 372 h. In the example shown, the multi-aperture arrays 372 ato 372 hare arranged on a circular ring. By a circular movement about the center point M of the circular ring-indicated by the double arrow-the multi-aperture arrays can each be introduced into the particle-optical beam path in a targeted manner and individually as an active multi-aperture array. The example shown is thus a carousel solution. A turret system solution is also conceivable in a slightly modified manner.FIG. 9 schematically shows a multiplicity of particle beam systems 1 having a storage chamber 392 for a microoptics module 380. Specifically, the plurality of particle beam system 1 includes a column chamber 390 that is evacuated. An operating position 391 for the micro-optics module 380 is arranged within the column. In FIG. 9A, the micro-optics module 380 ais located in this operating position 391. Outside the particle-optical beam path inside the storage chamber 392 is a further microoptics module 380 b. This is arranged in a storage position 393. The storage chamber 392, like the column chamber 390, is evacuated, and the two chambers 392 and 390 may be separated from each other or may communicate with each other. In any case, the further microoptical module 380 bis protected from particle beams by virtue of the fact that the storage chamber 392 is located outside the column chamber 390 and therefore remote from the particle-optical beam path. In addition, it is protected from X-rays, which does not, however, represent the main problem in the exemplary embodiment shown. Furthermore, the plurality of particle beam systems 1 comprises a lock chamber 389 with a lock 394 to the storage chamber 392.The arrows in FIGS. 9 aand 9 b now illustrate an exchange mechanism for exchanging the microoptics module 380 awith the further microoptics module 380 b: By means of a corresponding mechanism, which is indicated by the arrows in FIGS. 9 aand 9 b, the microoptics modules 380 aand 380 bmay be moved past one another and exchange their locations. The micro-optics module 380 acan be moved from the operating position 391 into the storage position 393. Accordingly, the additional micro-optics module 380 bmay be moved from the storage position 393 into the operating position 391. This stock with at least one further microoptics module 380 bin turn lengthens the maintenance interval on account of a necessary replacement of the microoptics module.Instead of providing a separate lock chamber 389, it is also possible to provide the storage chamber 392 itself with an outer door. This simplifies the exchange mechanism for the micro-optics module 380, but overall lengthens the time required to completely exchange a micro-optics module 380: namely, it is possible to carry out an evacuation and / or a ventilation process in the lock chamber 389 independently of the operation of the plurality of particle beam systems 1. This saves time.FIG. 10 shows, by way of example, a further multiplicity of particle beam system 1 having a storage chamber 392 for a multiplicity of microoptics modules 380 a, 380 band 380 c. In the exemplary embodiment shown, the storage chamber 392 is divided into three compartments 395, 396 and 397. Each compartment 395, 396, 397 may include a micro-optic module 380 a, 380 b, 380 cthat may be disposed in a storage position. A microoptics module 380 can then be replaced as follows: First, the storage chamber 392 is in a first position, as is shown in FIG. 10 a: the compartment 395 is at the level of the operating position 391 for a microoptics module 380. The microoptics module 380 acan be introduced by the compartment 395 under vacuum into the column chamber 390 through a lock (not shown) and arranged in the active operating position 391. It is then possible to return the "used" microoptics module 380a back to the compartment 395. This is illustrated in FIG. 10 b.The relative position of the storage chamber 392 to the column chamber 390 with the operating position 391 located therein for the microoptics module 380 can then be changed. This is indicated in FIG. 10 c by the double arrow in the height direction or z direction. After this relative movement, the compartment 396 with the microoptics module 380 barranged therein is now at the level of the operating position 391. The microoptics module 380 bcan be moved into the operating position 391 through a lock (not shown). This is illustrated in FIG. 10 d.Accordingly, the micro-optics module 380 cmay be further processed in the compartment 397, and so forth.Other mechanisms for moving a micro-optics module 380 into the column chamber 390 and the operating position 391 therein are also conceivable.In principle, because one or more microoptics modules 380 are already stored under vacuum, a more rapid exchange of a "used" microoptics module 380 for one of the stored microoptics modules 380 can take place. A stored microoptics module 380 is preferably transferred into the operating position, its qualification and alignment during an inactive time of the multiplicity of particle beam systems during which, for example, no measurement is carried out.Both in the exemplary embodiments shown in FIG. 9 and in the exemplary embodiments shown in FIG. 10, it is possible for the storage chamber 392 to have an outer door and / or for the storage chamber to have a vacuum and ventilation unit in order to build up a vacuum in the storage chamber 392 or to ventilate the storage chamber 392. In addition, it is possible for the storage chamber 392 to furthermore have a heating element (not shown) for heating out the storage chamber 392. Additionally or alternatively, the storage chamber 392 can have a plasma cleaning unit (not shown) in order to clean a stored microoptics module 380 and / or an exchanged microoptics module 380. As a result, secondary particles deposited on the micro-optics module 380 can be removed, for example, and the micro-optics module can be used once more for a longer time.In addition, it is possible, according to the principles illustrated in FIGS. 9 and 10, not only to store and replace a microoptics module 380 according to the arrangement of the pre-aperture module 370 and the microoptics module 380 according to the invention, but also to store and replace the entire arrangement with the pre-aperture module 370 and the microoptics module 380. Alternatively, instead of the arrangement according to the invention with pre-aperture module 370 and micro-optics module 380, it can also be a micro-optics or multi-aperture arrangement 305, as has been illustrated in connection with FIG. 2.Moreover, it is quite general that the described exemplary embodiments should not be understood as restrictive for the invention. Instead, they represent only possible exemplary embodiments.Disclosed is a multiplicity of particle beam systems 1 having an arrangement comprising a pre-aperture module 370 and a micro-optics module 380. The pre-aperture module 370 comprises a carrier plate 371 having a first set comprising at least two identical and thus functionally identical multi-aperture arrays 372 which have the same number N of apertures, the same shape and size of the apertures and the same arrangement of the apertures and are thus interchangeable. A mechanism for arranging the carrier plate 371 in the particle-optical beam path allows the exchange of functionally identical multi-aperture arrays in the event of damage to the active multi-aperture array, in particular on account of X-ray radiation. The microoptics module 380 arranged in the particle-optical beam path downstream of the pre-aperture module 370 is thereby better protected from x-rays occurring and has a longer lifetime. Maintenance intervals of the plurality of particle beam systems 1 can be extended.List of reference characters1 Multi-particle beam system, multi-beam particle microscope 3 primary particle beams, first single particle beams 5 beam spots, sites of impingement 7 object, sample, wafer 9 secondary particle beams, second single particle beams 10 computer system, controller 15 sample surface, wafer surface 25 image point of a second single particle beam 81 multipole electrode 82 ring electrode 83 spacer 84 ring electrode 85 aperture 86 spacer 99 absorbing and conducting layer 101 object plane 102 objective lens 103 field lens 105 axis 108 beam crossover, cross-over 200 detector system 205 projection lens system 206 projection lens 207 multi-particle detector 208 projection lens 209 projection lens 210 projection lens 212 beam crossover, cross-over 214 aperture filter, Contrast diaphragm 222 Collective anti-deflection system 300 Beam generating device 301 Particle source 303 Collimating lens system 304 Multi-aperture array, filter plate 305 Micro-optics, multi-aperture arrangement, multi-beam particle generator 306 Multi-aperture plate 307 Field lens, Aperture plate 308 Field lens 309 Particle beam 310 Multi-aperture plate 321 Intermediate image plane 323 Beam focus 333 Holding region 335 Membrane region 351 Aperture 370 Pre-aperture module 371 Carrier plate 372 Multi-aperture array 373 Lower aperture plate 374 Singular opening 375 Upper aperture plate 376 Singular opening 377 Round aperture 378 Round aperture 379 Elliptical aperture 380 Micro-optics module 381 Sequence of multi-aperture plates 382 Micro-optics holder 383 Passage 384 Fastening region 385 Outer region 386 Vacuum chamber 387 Vacuum chamber 388 Vacuum chamber 389 Lock chamber 390 Column chamber 391 Operating position for micro-optics / micro-optics module 392 Storage chamber 393 Storage position 394 Lock 395 Compartment 396 Compartment 397 Compartment 400 Beam splitter, Magnet arrangement 500 Scanning deflector 600 Moving table or positioning device x Direction y Direction z Direction M Center

Claims

A plurality of particle beam system (1) comprising: a particle source (301) for emitting charged particles; a pre-aperture module (370) comprising: a carrier plate (371), wherein the carrier plate (371) comprises a first set with at least two identical multi-aperture arrays (372) having the same number N of apertures (351), the same shape and size of the apertures (351) and the same arrangement of the apertures (351) and thus being interchangeable, a holding element for the carrier plate (371), and a mechanism for arranging the carrier plate (371) in the particle optical path and for replacing the at least two identical multi-aperture arrays (372) in the particle optical path with one another, wherein, during operation of the plurality of particle beam system (1), the carrier plate (371) is arranged in the particle-optical beam path of the plurality of particle beam system (1) such that the charged particles emitted by the particle source (301) strike only one of the at least two multi-aperture arrays (372) and pass through it to form a plurality of first individual particle beams N (3); and a micro-optics module (380) which is arranged in the particle-optical beam path after the pre-aperture module (370) and which has: a sequence of a plurality of multi-aperture plates (381) which form the micro-optics (335) and which are fixedly arranged relative to one another, and a micro-optics holder (382) for holding the micro-optics (335), wherein, during operation of the plurality of particle beam systems (1), the apertures (351) of the multi-aperture plates (306) are each penetrated by exactly one of the individual particle beams (3) and wherein the micro-optics (335) form the plurality of first individual particle beams (3) in a particle-optical manner.The plurality of particle beam system (1) according to the preceding claim, wherein the microoptics (335) comprise a multi-stigmator unit and / or wherein the microoptics (335) comprise a multi-lens array.The plurality of particle beam system (1) according to one of the preceding claims, wherein the sequence of multi-aperture plates (381) has a first multi-aperture plate, through which the first individual particle beams (3) formed in the pre-aperture module (370) pass as a first multi-aperture plate in the particle-optical beam path of the plurality of particle beam system (1), wherein the dimensions of the apertures (351) of the first multi-aperture plate are such that the first individual particle beams (3) pass through the apertures (351) of the first multi-aperture plate in a contactless manner.The multiple particle beam system (1) according to any one of the preceding claims, wherein the holding element of the carrier plate (371) is fixedly connected to or integrated into the micro-optics holder (382) of the micro-optics (335).The plurality of particle beam system (1) according to the preceding claim, wherein the micro-optics holder (382) has a flange by means of which the micro-optics holder (382) is sealingly installed in the plurality of particle beam system (1).The multiple particle beam system (1) according to the preceding claim, wherein the holding element of the carrier plate (371) is passed through the flange.The plurality of particle beam system (1) according to one of the preceding claims, wherein the pre-aperture module (370) further comprises a lower aperture plate (373) having a singular central opening (374), which is arranged in the particle-optical beam path between the carrier plate (371) and the micro-optics module (380) such that during operation of the plurality of particle beam system (1) the first individual particle beams (3) pass through the opening (374) of the lower aperture plate (373) in a contactless manner.The multiple particle beam system (1) according to the preceding claim, wherein the material of the lower aperture plate (373) is X-ray absorbing and in particular comprises copper.The multiple particle beam system (1) according to one of claims 7 to 8, wherein the following relationship applies for a distance D between the lower aperture plate (373) and an uppermost multi-aperture plate of the micro-optics module (380): D2 ≥ 0.5 cm, in particular D2 ≥ 1 cm or D2 ≥ 5 cm.The multiple particle beam system (1) according to any one of the preceding claims, wherein the pre-aperture module (370) further comprises an upper aperture plate (375) having a singular central opening (376) which is arranged in the particle-optical beam path above the carrier plate (371) such that the charged particles of the particle source partially or completely pass through the central opening (376) of the upper aperture plate (375).The multiple particle beam system (1) according to the preceding claim, wherein the material of the upper aperture plate (375) is X-ray absorbing and in particular comprises copper.The multiple particle beam system (1) according to claims 7 and 10, wherein the upper aperture plate (375) and the lower aperture plate (373) form walls of a pre-aperture chamber (398) for the carrier plate (371), and wherein the openings in the upper aperture plate (375) and / or the lower aperture plate (373) can be closed in a vacuum-tight manner.The plurality of particle beam system (1) according to the preceding claim, wherein the pre-aperture chamber (398) is accessible from outside the plurality of particle beam system (1).The multiple particle beam system (1) according to any one of the preceding claims, wherein the support plate (371) is linearly displaceable in a direction orthogonal to the particle optical path.The multiple particle beam system (1) according to any one of the preceding claims, wherein the carrier plate (371) is displaceable with two degrees of freedom within a plane oriented orthogonally to the particle optical beam path.The multiple particle beam system (1) according to any one of the preceding claims, wherein the carrier plate (371) is displaceable along the direction of the particle optical beam path.The plurality of particle beam system (1) according to one of the preceding claims, wherein multi-aperture arrays (372) of the carrier plate (371) can be introduced into the particle-optical beam path by means of a carousel or revolver system.The plurality of particle beam system (1) according to one of the preceding claims, wherein the apertures (377, 379) of the two multi-aperture arrays (372) are round or elliptical, and / or wherein the apertures of the two multi-aperture arrays (372) have a field profile.The multiple particle beam system (1) according to any one of the preceding claims, wherein the carrier plate (371) comprises at least one second set with at least two identical multi-aperture arrays, wherein apertures (377) of the multi-aperture arrays of the first set differ from the apertures (378) of the multi-aperture arrays of the second set.The plurality of particle beam system (1) according to any one of the preceding claims, wherein the plurality of particle beam system (1) further comprises: at least one further micro-optics module (380b) arranged within a vacuum but outside the particle-optical beam path of the plurality of particle beam system (1), and an exchange mechanism for exchanging the micro-optics module (380a) with the further micro-optics module (380b) under vacuum.The plurality of particle beam system (1) according to the preceding claim, wherein the plurality of particle beam system (1) has a storage chamber (392), in which the at least one further microoptical module (380b) is arranged, and wherein the storage chamber (392) is separated from the internal vacuum of the plurality of particle beam system (1) by means of a lock (394).The multiple particle beam system (1) according to the preceding claim, wherein the storage chamber (392) has an outer door; and / or wherein the storage chamber (392) has a vacuum and ventilation unit in order to build up a vacuum in the storage chamber (392) or to ventilate the storage chamber (392).The multiple particle beam system (1) according to one of claims 21 to 22, wherein the storage chamber (392) further comprises a heating element for baking the micro-optics module (380b); and / or wherein the storage chamber (392) comprises a plasma cleaning unit for cleaning a stored micro-optics module (380b) and / or an exchanged micro-optics module (380a).

Images