Particle-optical setup, in particular a multi-beam particle microscope, having a magnet setup for separating primary and secondary particle-optical beam paths

Abstract

A particle-optical mechanism, particularly a multi-beam particle microscope, is disclosed, having a magnet mechanism for separating primary and secondary particle-optical beam paths. The magnet mechanism includes a first magnetic field region through which the primary and secondary particle-optical beam paths pass, a second magnetic field region disposed in the primary particle-optical beam path but not in the secondary particle-optical beam path, and a third magnetic field region disposed in the primary particle-optical beam path but not in the secondary particle-optical beam path, the third magnetic field region disposed upstream of the second magnetic field region with respect to the primary particle-optical beam path, and the first and third magnetic field regions deflect the primary particle-optical beam path substantially in the same direction. The direction of incidence of the primary particle-optical beam path into the third magnetic field region and the direction of emergence of the primary particle-optical beam path from the first magnetic field region are parallel to each other and have no offset.

Description

[Technical Field]

[0001] The present invention relates to a particle-optical setup with an improved beam splitter, in particular to a particle-optical setup with a magnet arrangement for separating a primary particle-optical beam path and a secondary particle-optical beam path, and in particular to a multi-beam particle microscope. [Background technology]

[0002] With the continuous development of smaller and more complex microstructures, such as semiconductor components, there is a need to further develop and optimize planar manufacturing techniques and inspection systems for producing and inspecting small-dimension microstructures. For example, the development and production of semiconductor components requires oversight of test wafer designs, and planar manufacturing techniques require process optimization for reliable production with high throughput. Furthermore, recent years have seen a demand for analysis of semiconductor wafers for reverse engineering and for customer-specific individual configuration of semiconductor components. Therefore, there is a need for inspection tools that can be used with high throughput to examine the microstructures on wafers with high precision.

[0003] Typical silicon wafers used in the production of semiconductor components have a diameter of up to 300 mm. Each wafer can be up to 800 mm 2A semiconductor device includes multiple semiconductor structures fabricated in layers on the surface of a wafer using planar integration techniques. Semiconductor wafers typically have flat surfaces due to the production process. The feature sizes of integrated semiconductor structures range from a few microns to a critical dimension (CD) of 5 nm. The feature sizes are expected to become even smaller in the near future, with feature sizes or critical dimensions (CDs) expected to be less than 3 nm, e.g., 2 nm, or even less than 1 nm. With these small feature sizes, defects of the critical dimension size must be quickly identified within very large areas. For some applications, the specification requirements for the accuracy of measurements provided by inspection equipment are even higher, e.g., by two or even one order of magnitude. For example, the width of semiconductor features must be measured with an accuracy of less than 1 nm, e.g., 0.3 nm, or even less, and the relative positions of semiconductor structures must be determined with an overlay accuracy of less than 1 nm, e.g., 0.3 nm, or even less.

[0004] The MSEM, or multi-beam scanning electron microscope, is a relatively new development in the field of charged particle systems (charged particle microscopes, CPM). For example, U.S. Pat. No. 7,244,949 and U.S. Patent Application Publication No. 2019 / 0355544 disclose multi-beam scanning electron microscopes. In a multi-beam electron microscope or MSEM, a sample is simultaneously illuminated by multiple individual electron beams arranged in a field or raster. For example, an MSEM may provide 4 to 10,000 individual electron beams as primary radiation, each separated from adjacent individual electron beams by a pitch of 1 to 200 micrometers. For example, an MSEM may have approximately 100 separate individual electron beams ("beamlets") arranged in a hexagonal raster, with the individual electron beams separated by a pitch of approximately 10 micrometers. Multiple charged individual charged particle beams (primary beams) are focused onto the surface of a sample under investigation through a common objective lens. For example, the sample can be a semiconductor wafer fixed on a wafer holder mounted on a movable stage. During illumination of the wafer surface by the charged individual primary particle beams, interaction products, such as secondary electrons or backscattered electrons, emerge from the wafer surface. Their origins correspond in each case to the locations on the sample where the multiple individual primary particle beams are focused. The amount and energy of the interaction products depend on the material composition and topography of the wafer surface. The interaction products form multiple secondary individual particle beams (secondary beams), which are collected by a common objective lens and, as a result of the projection imaging system of the multi-beam inspection system, are incident on a detector located in a detection plane. The detector includes multiple detection areas, each containing multiple detection pixels, and captures the intensity distribution for each of the secondary individual particle beams. For example, an image field of 100 μm × 100 μm is acquired in the process.

[0005] Prior art multi-beam electron microscopes include a series of electrostatic and magnetic elements, at least some of which are adjustable to adapt the focal positions and astigmatism correction of the multiple charged individual particle beams. Prior art multi-beam systems using charged particles further include at least one crossover plane for the primary or secondary charged individual particle beams. Furthermore, prior art systems include a detection system to facilitate easier adjustment. Prior art multi-beam particle microscopes include at least one beam deflector ("deflection scanner") for simultaneous scanning of an area of the sample surface with the multiple primary individual particle beams to obtain an image field of the sample surface.

[0006] To separate the particle-optical beam path of the primary beam from the particle-optical beam path of the secondary beam, what are known as beam splitters (or alternatively as beam separators or beam dividers) are used, where the separation is performed using a special arrangement of magnetic and / or electrostatic fields, for example using a Wien filter.

[0007] The use of particle-optical components results in imaging aberrations quite commonly. When beam splitters are used, aberrations in the range of particle-optical imaging also occur, which need to be corrected if possible. Ideally, imaging aberrations should be avoided or corrected for all individual particle beams. As the image field becomes much larger in the range of particle-optical imaging, correction usually becomes even more important. In the case of multi-beam particle microscopes (multi-image field, so-called mFOV) that operate with several individual particle beams, the image field can become particularly large.

[0008] To correct aberrations caused by the beam splitter in a multi-beam particle microscope, EP 1668662 discloses the provision of an additional magnetic sector field in the primary path upstream of the actual separating magnetic sector field. Aberrations in the secondary path are corrected by up to three additional magnetic sector fields in the secondary path.

[0009] U.S. Patent No. 9,153,413 discloses a further beam splitter for a multi-beam particle microscope, in this case, correcting beam splitter-induced aberrations. The beam splitter operates according to the Wien filter principle. To correct the aberrations, the alignment or skew of each particle beam is corrected separately or individually using a multiple deflector array after passing through the beam splitter.

[0010] As the demand for resolution in multi-beam particle microscopes increases, so does the demand for aberration correction, and therefore there is a need for an overall improvement in terms of correction of beam splitter-induced imaging aberrations. Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention therefore aims to provide a particle-optical setup, and in particular a multi-beam particle microscope, in which beam splitter-induced aberrations occurring in particular in the primary path can be better corrected.

[0012] The object is achieved by the subject matter of the independent patent claims.

[0013] Advantageous embodiments of the invention are evident from the dependent patent claims.

[0014] This patent application claims priority from the German patent application having application number 102022120496.0 of August 12, 2022, the complete disclosure of which is incorporated by reference into the present patent application. [Means for solving the problem]

[0015] Aberrations that may typically occur in a multi-beam particle microscope include, for example, spherical aberration, astigmatism, coma, field curvature, distortion, chromatic aberration, or dispersion. In the case of the multi-beam particle microscope described in EP 1 668 662, which has the beam splitter already briefly described above or the above-described arrangement of magnetic sector fields or magnetic field regions, the imaging of the first individual particle beams into the object plane can already be substantially aberration-free in the first order, substantially free of distortion in the first order, and further free of dispersion as a whole. This should still be possible. The full disclosure of EP 1 668 662 is incorporated by reference into the present patent application.

[0016] Therefore, some have taken the first approach and attempted to provide an additional correction element for an existing beamsplitter while leaving the beamsplitter itself substantially unchanged. For example, this approach was taken to correct for field curvature.

[0017] However, more recent and more precise investigations (high-precision measurements of what are known as focus maps) have surprisingly shown that the remaining dominant residual error during particle-optical imaging is often not field curvature but field inclination. In the case of field inclination, the focal position of the first individual particle beam relative to the (ideal) object plane varies linearly with the distance from the optical axis; in contrast, in the case of field curvature, the focal position varies quadratically with the distance from the optical axis. In DE 2021200799 several compensators have already been proposed to correct for field inclination.

[0018] Unlike field curvature, for example, field tilt is a non-rotationally symmetric aberration. A possible cause of non-rotationally symmetric aberrations in existing beam splitters can be found in a broken symmetry in the beam splitter. The angle between the optical axis at the entrance of the first-order beam into the beam splitter and the optical axis at the emergence of the first-order beam from the beam splitter (the "skew angle") can contribute to this symmetry breaking. Therefore, the present invention proposes a modified design for the beam splitter itself or for the associated magnet mechanism. In particular, field tilt can be simultaneously corrected, or even not occur if the beam splitter design is appropriately selected. This is because field tilt is essentially the result of slight path differences between the various individual particle beams as they pass through the beam splitter. According to the inventors' investigations, these path length differences arise decisively in the case of the design according to EP 1 668 662 as a result of the angle (the so-called "skew angle") that exists between the optical axis of the primary beam at the time of its entry into the beam splitter and the optical axis at the time of its emergence from the beam splitter. Therefore, the primary beam column is slightly tilted relative to the rest of the structure or relative to the lower region of the column in the area of the objective lens and the sample. Similarly, imprecise collimation of the individual particle beams into the beam splitter can contribute to path length differences, as can the inclination of the magnetic field region or the recess of the sector relative to the optical axis.

[0019] Therefore, according to the present invention, an aligned optical axis design for a beam splitter is proposed, which further provides at least the same number of operating parameters for correcting aberrations, or even more, compared to designs known from the prior art. In the case of the aligned optical axis design, the skew angle is omitted, which, in addition to the improved imaging properties of the beam splitter, provides significant advantages during the manufacture and adjustment of multi-beam particle microscopes.

[0020] According to a first aspect of the invention, the latter therefore comprises a particle-optical arrangement for providing a primary particle-optical beam path for a plurality of first individual charged particle beams emanating from a multi-beam particle generator and directed towards an object positionable in an object plane of the arrangement, and a secondary particle-optical beam path for a plurality of second individual charged particle beams emanating from the object, the particle-optical arrangement comprising: The particle-optical mechanism comprises a magnet mechanism, a first magnetic field region through which the primary particle-optical beam path and the second particle-optical beam path pass, for separating the primary particle-optical beam path and the second particle-optical beam path from each other; a second magnetic field region disposed in the primary particle optical beam path and not in the secondary particle optical beam path, the second magnetic field region being disposed upstream of the first magnetic field region with respect to the primary particle optical beam path, the first magnetic field region and the second magnetic field region substantially deflecting the primary particle optical beam path in different directions; a third magnetic field region disposed in the primary particle optical beam path and not in the secondary particle optical beam path, the third magnetic field region being disposed upstream of the second magnetic field region with respect to the primary particle optical beam path, the first and third magnetic field regions substantially deflecting the primary particle optical beam path in the same direction; Including, The particle-optical arrangement relates to a particle-optical arrangement in which the direction of incidence of the primary particle optical beam path into the third magnetic field region and the direction of emergence of the primary particle optical beam path from the first magnetic field region are substantially parallel to each other and have substantially no offset. As a result of this condition, the magnet arrangement therefore has an "aligned optical axis" for the primary particle optical beam path. This aligned optical axis characteristic can be obtained with high precision, with the error or angle between the direction of incidence of the primary particle optical beam path into the third magnetic field region and the direction of emergence of the primary particle optical beam path from the first magnetic field region being 4 mrad or less, preferably 1 mrad or less, or most preferably 0.1 mrad or less. The error in the no-offset characteristic is similarly very small, for example, + / - 0.6 mm or less, preferably + / - 0.3 mm, + / - 0.1 mm, or even + / - 0.05 mm.

[0021] For example, if the particle-optical system is a multi-beam particle microscope, then—unlike the prior art—the first individual particle beams can reach the sample even when the beam splitter or magnet system is switched off. In this way, the intended operation of the magnet system and other particle-optical imaging components can be checked much more easily. The manufacture of the multi-beam particle microscope as a whole is also significantly simplified in this way.

[0022] Deflection of the particle beam in substantially the same direction may be achieved using magnetic fields oriented in substantially the same direction, in which case the magnetic field strength in the two magnetic field regions may be the same or different.

[0023] Deflection of the particle beam in substantially different directions can be achieved using magnetic fields oriented in substantially opposite directions, in which case the magnetic field strength in the two magnetic field regions can be substantially the same or different.

[0024] Because the primary path of the particle-optical system provides one more magnetic field region than in the prior art, the magnet system also offers ample options for optimization approaches aimed at aberration correction, since there are at least as many independent operational parameters as in previous systems. The operational parameters for the magnet system are, in particular, the positions (height or z-position) of the entrance and exit points into and out of the various magnetic field regions, as well as the associated entrance or exit angles. By defining these operational parameters, it is possible to set the respective arc lengths within the magnetic field region that the first individual charged particle beams travel through (for a given magnetic field and a given kinetic energy of the charged particles).

[0025] The magnetic field regions themselves can be formed in a manner known per se. They are designed in particular to generate a uniform magnetic field whose direction is oriented perpendicular to the direction of motion of the first individual particle beam. By way of example, the magnetic field regions can each be formed by two spaced apart slabs of magnetizable material, each having a milled recess into which a current conductor or coil is inserted. However, other embodiments are also possible.

[0026] The first individual charged particle beam can be, for example, electrons, positrons, muons, ions, or other charged particles. The second individual charged particle beam can be mirror particles of the first individual charged particle beam, such as secondary electrons or backscattered electrons. In principle, the particle-optical setup can therefore be used flexibly.

[0027] The terms primary particle-optical beam path and secondary particle-optical beam path are used as is customary in the art. However, attention is drawn here to the fact that primary particle-optical beam path, as well as secondary particle-optical beam path, describe paths of a plurality of first or second individual particle beams. However, for simplicity, it will be appreciated that—depending on the context—the terms primary particle-optical beam path and secondary particle-optical beam path may refer only to the individual particle beams, or the central beam, moving along the optical axis of the system.

[0028] According to a preferred embodiment of the present invention, a first drift region substantially free of a magnetic field is disposed in the primary particle-optical beam path between the first and second magnetic field regions, and / or a second drift region substantially free of a magnetic field is disposed in the primary particle-optical beam path between the second and third magnetic field regions. In this case, the first and second drift regions may have different lengths and orientations. Providing a drift region between the magnetic field regions offers advantages in the design of the particle-optical system, particularly for a given entry point into the particle-optical system and a given exit point from the particle-optical system. This is because it creates more independent operating parameters for the magnet system and provides more options for correcting imaging aberrations. Furthermore, a larger distance between the magnetic field regions contributes to reducing or avoiding interaction effects between the magnetic field regions. Furthermore, the spatial separation between the primary and secondary particle beams can be enhanced.

[0029] According to a further preferred embodiment of the present invention, the magnet arrangement has a fourth magnetic field region arranged in the primary particle optical beam path and not arranged in the secondary particle optical beam path, the fourth magnetic field region is disposed upstream of the second magnetic field region and downstream of the third magnetic field region with respect to the primary particle optical beam path; The fourth magnetic field region and the second magnetic field region substantially deflect the primary particle optical beam path in the same direction. The provision of a fourth magnetic field region has the advantage that further operating parameters become available for the correction of aberrations, which can be up to four further operating parameters (e.g., the height of entry into and exit from the magnetic field region, and the inclination of the magnetic field region or groove relative to the optical axis of the primary particle optical beam path at entry or exit).

[0030] According to a further preferred embodiment of the present invention, the particle-optical mechanism has a first drift region in which a magnetic field is substantially absent and which is arranged in the primary particle-optical beam path between the first and second magnetic field regions. Additionally or alternatively, the particle-optical mechanism has a second drift region in which a magnetic field is substantially absent and which is arranged in the primary particle-optical beam path between the second and fourth magnetic field regions. Additionally or alternatively, the particle-optical mechanism has a third drift region in which a magnetic field is substantially absent and which is arranged in the primary particle-optical beam path between the fourth and third magnetic field regions. Also in this variant of the present embodiment of the present invention, the provision of drift regions contributes to increasing the number of parameters of the magnet mechanism that can be adjusted independently of each other.

[0031] According to a further preferred embodiment of the present invention, the magnet arrangement has no additional magnetic field regions in the primary particle optical beam path designed to deflect the primary particle optical beam path by more than 2°, preferably more than 1°, and most preferably more than 0.5°. In other words, according to this preferred embodiment, either exactly three magnetic field regions or exactly four magnetic field regions must be provided in the primary particle optical beam path. Limiting the number of magnetic field regions in the primary particle optical beam path provides the advantage that the first individual particle beams are not focused excessively strongly as a whole during their movement through the magnet arrangement. This is because, due to the resulting quadrupole fields, the first individual charged particle beams each experience focusing, albeit weakly, upon entering or exiting each magnetic field region. Limiting the number of magnetic field regions to a relatively small number also simultaneously limits this focusing, which is generally undesirable.

[0032] According to a further preferred embodiment of the present invention, the magnet arrangement of the particle-optical arrangement is configured such that there are substantially no path differences for the first individual particle beams as they pass through the magnet arrangement, e.g., this eliminates or reduces field tilt.

[0033] According to a preferred embodiment of the present invention, the magnet mechanism of the particle-optical mechanism has a symmetry plane, and the primary particle-optical beam path is mirror-symmetric with respect to the symmetry plane as it passes through the magnet mechanism. Therefore, this symmetry plane can then be located midway between the point of entry of the primary particle-optical beam path into the magnet mechanism as a whole and the point of exit of the primary particle-optical beam path from the magnet mechanism as a whole. If the magnet mechanism as a whole has exactly three magnetic field regions, the symmetry plane intersects with the second magnetic field region. If the magnet mechanism as a whole has four magnetic field regions, the symmetry plane is located between the second and fourth magnetic field regions. The symmetry condition with respect to the symmetry plane relates to the particle-optical beam path, and in particular, to the principal lines, and does not automatically relate to the design of the magnetic field regions themselves. Nevertheless, some magnetic field regions may have identical or mirror-identical dimensions, which may be advantageous from a manufacturing standpoint. Furthermore, the symmetric design of the magnet mechanism results in the elimination of five second-order aberration terms (out of a total of 18 linearly independent second-order aberration terms). Generally, each symmetry requirement reduces the number of operating parameters that can be adjusted independently of one another. Nevertheless, if corresponding drift paths are provided in the magnet arrangement, as already explained in detail above, there remains in principle a sufficient number of operating parameters that can be adjusted independently of one another.

[0034] According to a preferred embodiment of the present invention, the direction of the magnetic field in all of the magnetic field regions of the magnet arrangement is substantially perpendicular to the optical axis of the primary particle optical beam path during operation of the particle-optical arrangement, and the magnetic field is substantially uniform. Therefore, the trajectory (with trajectory radius r) within the magnet arrangement described by the first individual particle beam is B ) can be adjusted in a better and more precise manner. For example, if the following equation is true for the orbit radius r B Applicable to: 0.1m≦r B ≦10.0 m.

[0035] According to a further preferred embodiment of the present invention, the uniform magnetic fields in the magnetic field region in the primary particle-optical beam path each have an absolute value of the magnetic field strength during operation of the particle-optical arrangement, the magnetic fields each being assigned a sign, the sign characterizing the direction of the magnetic field; The sum of the signed absolute value of the magnetic field strength, summed over all magnetic field regions in the primary particle optical beam path, and the associated arc length within the magnetic field region along which the primary particle optical beam path travels is zero to a first approximation. This condition applies to the central beam to a first approximation. This is a necessary, but not sufficient, condition for the aligned optical axis characteristics of the magnet system. The direction of entry of the primary particle optical beam path into the third magnetic field region and the direction of exit of the primary particle optical beam path from the first magnetic field region are then substantially parallel to each other. However, in principle, an offset can still occur. This can be eliminated by appropriate selection of the drift paths or their lengths. For example, if there are a total of three magnetic field regions and the first and second drift regions are respectively positioned between two magnetic field regions, then the lengths of the two drift regions must be identical to avoid any offset. For example, if a total of four magnetic field regions are provided for the magnet arrangement, with each drift region being provided between two magnetic field regions, then the lengths of the first and last drift regions can be chosen, for example, to be identical, with the central drift region extending parallel to the (already vectorially identical) entrance or exit direction of the primary particle optical beam path into / out of the magnet arrangement. Quite generally, for a magnet arrangement with an aligned optical axis relative to the primary particle optical beam path, it can be said that the vector sum of the drift paths as a whole is a vector that is a multiple of the entrance direction of the primary particle optical beam path into the magnet arrangement as a whole. In any case, this applies when the magnetic field strength is identical in all magnetic field regions. In addition to the above conditions for the particle-optical beam path of the central beam, the magnet arrangement is preferably designed such that there are substantially no path length differences between the various first individual particle beams as they travel through the magnet arrangement, even for off-axis beams in the case of divergent or convergent entrance of the first individual particle beams into the magnet arrangement and / or in the case of divergent or convergent emergence of the first individual particle beams from the magnet arrangement.

[0036] According to a preferred embodiment of the present invention, the following relationship applies to the separation angle γ, by which the primary particle optical beam path is deflected as a whole in the first magnetic field region during operation of the particle-optical mechanism: γ≧2°, preferably γ≧5°, and most preferably γ≧10°. The separation angle in this case is a measure for the maximum possible separation of the primary particle optical beam path from the secondary particle optical beam path. The separation angle γ must not be selected to be too small. Otherwise, the additional magnetic field region for the secondary particle optical beam path cannot be integrated into the magnet mechanism of the particle-optical mechanism without problems. For example, the additional magnetic field region to be assigned exclusively to the secondary particle optical beam path could collide with the magnetic field region of the primary particle optical beam path. For example, this could result in crosstalk between the various magnetic field regions.

[0037] According to a further preferred embodiment of the present invention, the total length of the magnet arrangement, as defined by the distance between the point of entry of the primary particle optical beam path into the third magnetic field region and the point of exit of the primary particle optical beam path from the first magnetic field region, is 1.0 m or less, preferably 0.5 m or less, and most preferably 0.3 m or less.

[0038] According to a further preferred embodiment of the present invention, each magnetic field region has an entrance region for the primary particle optical beam path with an entrance tilt and an exit region for the primary particle optical beam path with an exit tilt, the exit tilt of the first magnetic field region being substantially 0°. Here, the entrance tilt is defined as the angle at which the alignment of the entrance region deviates from the normal to the optical axis of the primary particle optical beam path, and the exit tilt is defined as the angle at which the alignment of the exit region deviates from the normal to the optical axis of the primary particle optical beam path. Providing that the exit tilt of the first magnetic field region is substantially 0° ensures that the optical axis of an objective lens further down in the primary particle optical beam path can correspond to or coincide with the exit direction of the primary particle optical beam path. This facilitates further configuration of the particle-optical setup as a whole.

[0039] According to a preferred embodiment of the present invention, the incidence tilt of the third magnetic field region is substantially 0°, which in turn can further facilitate further configuration of particle-optical mechanisms within the primary particle-optical beam path, while the 0° tilt can indicate a condition for establishing symmetry within the aligned optical axis magnet mechanism.

[0040] According to a preferred embodiment of the present invention, the particle-optical arrangement is arranged upstream of the third magnetic field region in the direction of the primary particle optical beam path and is configured to set the direction of incidence of the primary particle optical beam path into the third magnetic field region with an accuracy of + / −0.1° or better, in particular with an accuracy of + / −0.05° or better, or with an accuracy of + / −0.025° or better, and therefore to set, for example, a required incidence tilt of 0°, and further comprises a deflector arrangement configured to set the location of incidence of the primary particle optical beam path into the third magnetic field region with an accuracy of + / −0.3 mm or better, in particular with an accuracy of + / −0.1 mm or better, or even with an accuracy of + / −0.05 mm or better. Preferably, the deflector arrangement includes two adjusting deflectors that can be adjusted precisely and independently of each other, so that both the offset and the skew of the first individual particle beams upon incidence into the magnet arrangement can be set precisely and independently of each other. This prevents possible re-occurrence of beam splitter aberrations, such as field tilt, field astigmatism, global astigmatism, or other second- or third-order aberrations, which were actually previously corrected using the design of the magnet mechanism, in the case of input coupling of a skewed or offset beam.

[0041] According to a preferred embodiment of the present invention, the entrance gradient of the first magnetic field region is selected such that the exit angle σ of the secondary particle optical beam path from this first magnetic field region is limited to σ≦35°, preferably σ≦25° or most preferably σ≦15°. This avoids the collection of large aberrations on emergence from the first magnetic field region and creates additional installation space for possible additional secondary path magnetic field regions in the gap between the first and second magnetic field regions. Further details on this point are provided below.

[0042] According to a preferred embodiment of the present invention, the magnet mechanism includes a beam tube mechanism through which the primary particle optical beam path extends, the beam tube mechanism having a torus topology. As a result, when the primary path beam splitter is switched off or when the magnetic field region in the primary particle optical beam path is switched off, the alignment optical axis characteristics of the magnet mechanism can be used for adjustment purposes. The torus topology describes, in a very general sense, two branches of the beam tube mechanism, whereby when the magnetic field region is switched off, the primary particle optical beam path can split in a first branch and recombine in a second branch.

[0043] According to a preferred embodiment of the present invention, the following relationship applies to the fill factor F of the beam tube system during operation of the particle-optical system: F≦50%, preferably F≦30%, or most preferably F≦10%. In this case, the fill factor is given as the ratio of the maximum diameter S of the beam (total of the individual particle beams of the first order) to the inner diameter R of the beam tube or beam tube system. In this case, the beam tube is made of a non-magnetic material. For a given maximum diameter S of the beam, the inner diameter R of the beam tube can be appropriately dimensioned. This minimizes contamination of the beam tube as a result of the interaction of the charged particle beam during operation in order to avoid undesired beam deflections due to charged contamination spots inside the beam tube.

[0044] According to an alternative preferred embodiment of the present invention, the magnet mechanism does not include a beam tube mechanism through which the primary particle optical beam path extends within the magnet mechanism. The beam tube mechanism used in the prior art limits the space for the individual particle beams to be manipulated as they pass through the magnet mechanism. However, if the alignment optical axis design of the magnet mechanism according to the present invention is to enable checking of the primary particle optical beam path when the magnet mechanism is switched off, the space limitation for the particle beams to be manipulated provided by the beam tube mechanism can be an obstacle. Further details can be gleaned, for example, from GB Patent Application Publication No. 000002519511, the full disclosure of which is incorporated herein by reference. According to a preferred embodiment of the present invention, the magnet mechanism therefore includes a vacuum chamber through which the primary particle optical beam path and / or the secondary particle optical beam path extend within the magnet mechanism. The necessary free movement of the individual particle beams is provided within this vacuum chamber. In principle, arranging or fixing the individual magnetic field regions within the vacuum chamber can be performed in a manner already known per se.

[0045] According to a preferred embodiment of the invention, the magnet arrangement has at least two further magnetic field regions in the secondary particle-optical beam path after passing through the first magnetic field region, the at least two further magnetic field regions being configured to precisely couple the particle-optical axis in the secondary beam path into the downstream projection optical unit with respect to offset and angle when the energy of the secondary particles, whose path forms the second particle-optical beam path, is variable. For example, a change in the energy of the secondary particles can be the result of changing the landing energy setting.

[0046] According to a preferred embodiment of the present invention, the magnet arrangement has at least six further magnetic field regions and / or quadrupole fields in the secondary particle optical beam path after passing through the first magnetic field region, and the at least six further magnetic field regions and / or quadrupole fields are configured to precisely couple the particle optical axis in the secondary beam path into a downstream projection optical unit in terms of offset and angle when the energy of the secondary particles whose path forms the second particle optical beam path is variable, and additionally to enable imaging that is paraxial aberration-free, has no paraxial distortion aberration, and has no paraxial dispersion.

[0047] According to a further preferred embodiment of the invention, at least one of the further magnetic field regions of the secondary particle optical beam path is arranged in a gap between the first and second magnetic field regions of the primary particle optical beam path.

[0048] According to a further preferred embodiment of the present invention, the magnet arrangement further comprises a magnetic shielding wall arranged between at least one of the magnetic field regions of the primary particle optical beam path and at least one of the magnetic field regions of the secondary particle optical beam path. Of course, it may also be arranged substantially continuously between all of the magnetic field regions of the primary particle optical beam path and all of the magnetic field regions of the secondary particle optical beam path. By way of example, the magnetic shielding wall comprises a web of soft magnetic material that minimizes crosstalk between the primary and secondary path magnetic field regions.

[0049] According to a further preferred embodiment of the present invention, the magnetic shielding wall has an open channel through which the first particle-optical beam path passes linearly along the particle-optical axis when the magnet mechanism is switched off. As a result, the alignment optical axis characteristics of the magnet mechanism when the magnetic field region of the primary path is switched off can be used for adjustment purposes. The open channel can be characterized by a ratio K of the channel length L to the channel width B. For example, if K≧3, preferably K≧5, or most preferably K≧10, magnetic shielding between the magnetic field regions of the primary and secondary paths is well ensured despite the open channel.

[0050] According to a further preferred embodiment of the present invention, the particle-optical setup is a multi-beam particle microscope, the particle-optical setup comprising: a multi-beam particle generator configured to generate a first field of a plurality of charged first individual particle beams; a first particle-optical unit having a primary particle-optical beam path configured to image the generated first individual particle beam onto an object plane such that the first individual particle beam impinges on the object at an incidence location that forms a second field of view; a detection unit having a plurality of detection areas forming a third field of view; a second particle-optical unit having a secondary particle-optical beam path configured to image a second individual particle beam emanating from an incidence location within the second field of view onto a third field of view of a detection region of the detection system; a magnetic and / or electrostatic objective lens through which both the first and second individual particle beams pass; a controller configured to control particle-optical components in the primary particle-optical beam path and / or the secondary particle-optical beam path and / or components of the magnet arrangement; and The magnet mechanism is disposed in a first particle-optical beam path between the multi-beam particle generator and the objective lens, and the magnet mechanism is disposed in a second particle-optical beam path between the objective lens and the detection unit.

[0051] The first individual charged particle beam can be, for example, electrons, positrons, muons, ions, or other charged particles. It is advantageous for the number of first individual particle beams to be 3n(n-1)+1, where n is any natural number. In this case, the first individual particle beams can be arranged within a hexagonal field of view. However, other arrangements of the first individual particle beams are also possible. The second individual particle beam can be backscattered electrons or other secondary electrons. In this case, for analytical purposes, low-energy secondary electrons are preferably used for image generation. However, mirror ions / mirror electrons can also be used as the second individual particle beam. That is, the first individual particle beam undergoes reversal immediately upstream of or at the object.

[0052] Naturally, the magnet arrangement of the multi-beam particle microscope can still be expanded or improved for the secondary particle optical beam path, as already described above. According to a preferred embodiment, the magnet arrangement has at least one additional magnetic field region in the secondary particle optical beam path. For example, as already described in the prior art in EP 1 668 662, it is possible to arrange one, two, or three additional magnetic field regions in the secondary particle optical beam path. As a result, imaging aberrations resulting from the magnet arrangement or beam splitter can also be corrected in the secondary particle optical beam path.

[0053] According to a preferred embodiment of the present invention, the imaging of the first individual particle beams onto the object plane exhibits substantially no image plane tilt. Of course, it is also possible to correct other imaging aberrations through appropriate design of the magnet arrangement, as already explained in detail above.

[0054] According to a preferred embodiment of the invention, the imaging of the plurality of first individual particle beams into the object plane as a whole is substantially free of distortion, and / or the imaging of the first individual particle beam into the object plane is substantially dispersion-free, and / or The location of incidence of the first individual particle beam in the object plane is astigmatic and circular. Additionally or alternatively, it is also possible to correct other aberrations in the field of particle-optical imaging. Depending on the design, the magnet arrangement according to the invention also provides suitable operating parameters for correction purposes. Corrections can also include correction of sample skew and / or correction of focal tilt as a result of misalignment of the illumination system / condenser lens system.

[0055] According to a preferred embodiment of the invention, the imaging of the first individual particle beam into the object plane is free of field astigmatism.

[0056] According to a preferred embodiment of the invention, the sum of all other second and third order aberrations in the object plane is no more than 1 nm, in particular no more than 0.5 nm or no more than 0.25 nm.

[0057] The above-described embodiments can be combined with each other fully or partially as long as no technical contradictions result.

[0058] The present invention will be better understood with reference to the accompanying drawings. [Brief explanation of the drawings]

[0059] [Figure 1] 1 is a schematic diagram of a multi-beam particle microscope; [Figure 2] 1 shows a schematic diagram of a multi-beam particle microscope with a beam splitter or magnet arrangement according to the prior art; [Figure 3] 1A and 1B are diagrams illustrating a magnet mechanism according to the prior art and the occurrence of image plane tilt. [Figure 4] FIG. 10 shows a schematic diagram of the operating parameters for a magnet arrangement having two magnetic field regions in the primary path. [Figure 5] FIG. 10 is a diagram illustrating the operating parameters for a magnet arrangement having three magnetic field regions in the primary path. [Figure 6]FIG. 10 is a diagram illustrating the operating parameters for a symmetrized magnet mechanism with three magnetic field regions in the primary path. [Figure 7] FIG. 10 is a diagram illustrating the operating parameters for a symmetrized magnet mechanism having four magnetic field regions in the primary path. [Figure 8] FIG. 2 shows a schematic diagram of the placement or alignment of a first magnetic field region in a particle-optical beam path. DETAILED DESCRIPTION OF THE INVENTION

[0060] FIG. 1 shows a schematic diagram of a multi-beam particle microscope 1. The multi-beam particle microscope 1 comprises a beam generator 300 having a particle source 301, e.g., an electron source. A diverging particle beam 309 is collimated by a series of condenser lenses 303.1 and 303.2 and impinges on a multi-aperture mechanism 305. The multi-aperture mechanism 305 includes multiple multi-aperture plates 306 and a field lens 308. Multiple individual particle beams 3 or individual electron beams 3 are generated by the multi-aperture mechanism. The midpoints of the apertures in the multi-aperture plate mechanism are positioned within a field that is imaged onto a further field formed by a beam spot 5 in the object plane 101. The pitch between the midpoints of the apertures of the multi-aperture plate 306 can be, for example, 5 μm, 100 μm, or 200 μm. The diameter D of the apertures is less than the pitch between the midpoints of the apertures, with example diameters being 0.2, 0.4, and 0.8 times the pitch between the midpoints of the apertures.

[0061] The multi-aperture mechanism 305 and field lens 307 are configured to generate a raster array of multiple focal points 323 of the primary beam 3 on a surface 325. The surface 325 does not have to be a planar surface, but can be a spherically curved surface to accommodate the field curvature of the subsequent particle optics.

[0062] The multi-beam particle microscope 1 further comprises a system of electromagnetic lenses 103 and objective lenses 102, which image a beam focus 323 having a reduced size from the intermediate image surface 325 into the object plane 101. Between them, the first individual particle beams 3 pass through a beam splitter 400 and a collective beam deflection system 500, which deflect the first individual particle beams 3 in operation to scan the image field. The first individual particle beams 3 incident in the object plane 101 form, for example, a substantially regular field, and the pitch between adjacent incident locations 5 can be, for example, 1 μm, 10 μm, or 40 μm. By way of example, the field formed by the incident locations 5 can have four- or six-gonal symmetry.

[0063] The object 7 to be investigated can be of any desired type, for example a semiconductor wafer or a biological sample, and can include an array of micropatterned elements or the like. The surface 15 of the object 7 is located in the object plane 101 of the objective lens 102. The objective lens 102 can include one or more electron-optical lenses. By way of example, this can be a magnetic objective lens and / or an electrostatic objective lens.

[0064] The primary particles 3 incident on the object 7 generate interaction products, such as secondary electrons, back electrons, or primary particles that have undergone a reversal of motion for other reasons. These interaction products originate from the surface of the object 7 or from the first plane 101 or object plane 101. The interaction products originating from the surface 15 of the object 7 are shaped by the objective lens 102 to form a secondary particle beam 9. In the process, the secondary beam 9 passes through a beam splitter 400 after the objective lens 102 and is supplied to a projection system 200. The projection system 200 includes an imaging system 205 having first and second lenses 210 and 220, a contrast stop 222, and a multi-particle detector 209. The incidence locations of the second individual particle beams 9 on the detection area of the multi-particle detector 209 are arranged within the third field of view with a regular mutual pitch. Exemplary values are 10 μm, 100 μm, and 200 μm.

[0065] The multi-beam particle microscope 1 further comprises a computer system or control unit 10, which in turn may be made in one part or in many parts and is designed to control the individual particle-optical components of the multi-beam particle microscope 1 as well as to evaluate and analyze the signals obtained by the multi-detector 209 or detection unit 209.

[0066] Further information relating to such a multi-beam particle beam system or multi-beam particle microscope 1 and the components used therein, such as, for example, the particle source, the multi-aperture plate, and the lenses, can be gleaned from international patent applications WO 2005 / 024881, WO 2007 / 028595, WO 2007 / 028596, WO 2011 / 124352, and WO 2007 / 060017, and from German patent applications DE 102013016113 and DE 102013014976, the full disclosures of which are incorporated herein by reference.

[0067] The beam splitter 400 or magnet arrangement 400 is shown only diagrammatically and without further details in Fig. 1. In principle, the magnet arrangement 400 can be the magnet arrangement 400 included in the particle-optical arrangement according to the invention. However, beam splitters 400 known from the prior art or from EP 1 668 662 are also suitable for the multi-beam particle microscope 1 according to Fig. 1.

[0068] FIG. 2 shows a schematic cross-sectional view of a multi-beam particle microscope 1 having a beam splitter 400 or magnet arrangement 400 according to the prior art. A special aspect of the known beam splitter 400 is described here. In the multi-beam particle microscope 1 shown in FIG. 2, a particle beam emitted by a particle source 301 passes through a magneto-optical condenser lens system 303 and then impinges on a multi-aperture arrangement 305. The latter acts as a multi-beam particle generator, and the individual particle beams 3 emerging from the multi-aperture arrangement 305 then immediately pass through a magneto-optical field lens system 307 and then enter the magneto-optical beam splitter 400 or magnet arrangement 400. The illustrated beam splitter 400 includes a beam tube arrangement 490, which in the illustrated example has a Y-shaped embodiment and includes three limbs 461, 462, and 463. Here, in addition to two planar interconnected structures for holding the magnetic sectors or magnetic field regions 410, 430, the beam splitter 400 includes two magnetic sectors or magnetic field regions 410 and 430, either contained within or fixed to the aforementioned structure. After passing through the beam splitter 400, the first particle beam 3 passes through a scanning deflector 500 and immediately thereafter through a particle-optical objective lens 102 before the primary particle beam 3 impinges on an object 7, in this case, a surface 15 of a semiconductor wafer having an HV structure. In this case, the HV structure represents the predominantly horizontal or vertical profile of the semiconductor structure. In this case, the semiconductor wafer 7 is positioned below the objective lens 102 by a displacement stage 600. As a result of the incidence of the first individual particle beam 3, secondary particles or second individual particle beams 9 are emitted from the object 7. After emerging from the object 7, the second individual particle beam 9 first passes through the particle-optical objective 102, then through the scanning deflector 500 and then through the beam splitter 400. From the beam splitter 400, the second individual particle beam 9 emerges from limb 462, passes through the projection lens system 205 (shown in a very simplified manner), passes through an electrostatic element 260, the so-called anti-scan, and then impinges on the particle-optical detection unit 209.The computer system 10 or control unit 10 responsible for controlling the particle-optical components and other components of the multi-beam particle microscope 1 of FIG. 2 is not shown in FIG. 2 to keep things simple.

[0069] From the prior art beam splitter 400 it is clear that the provision of the beam tube 490 brings advantages because of the structure shown and because of the necessary evacuation around the first and second particle-optical beam paths 13 and 11, respectively, within the beam splitter 400. However, it is also clear that the first particle-optical beam path 13 cannot pass through the beam splitter 400 when the beam splitter 400 is switched off, but instead hits the wall of the beam tube 490. This makes the adjustment of the multi-beam particle microscope 1 more difficult, since the contribution of the beam splitter 400 to possible misalignments cannot be investigated separately.

[0070] FIG. 3 is a schematic diagram illustrating a prior art magnet mechanism and the generation of image plane tilt. In the illustrated example, the magnet mechanism 400 includes a first magnetic field region 410 and a second magnetic field region 430, with the magnetic fields of both magnetic field regions oriented in opposite directions, and the primary particle-optical beam path 13 passes through both of these magnetic field regions. Additionally, in the illustrated example, three additional magnetic field regions 450, 460, and 470 are provided. The secondary particle-optical beam path 11 extends through the first magnetic field region 410 and through these additional magnetic field regions 450, 460, and 470. The magnetic field in magnetic field region 450 is oriented in the same direction as the magnetic field in magnetic field region 410, so that the curvature of the second particle-optical beam path 11 does not change within these magnetic field regions 410, 450.

[0071] 3 is not of the aligned optical axis type. Instead, there is a skew angle β between the optical axis of the first particle-optical beam path 13 and axis A, which corresponds to the optical axis of the objective lens 102 or an extension thereof. A right angle is set between the lower edge of the first magnetic field region 410 and axis A, which is advantageous for the properties of the imaging into the object plane 101 as a whole. The skew angle β requires special precision measurements when the multi-beam particle microscope 1 is manufactured, which is much more time-consuming and costly than in the aligned optical axis or Cartesian configurations, where the skew angle β would be zero.

[0072] The angle γ is the so-called separation angle, which provides a measure for the separation of the primary particle optical beam path 13 from the second particle optical beam path 11 in the magnetic field region 410. This angle must not be chosen to be too small, otherwise there may not be enough installation space available for the arrangement of the magnetic field regions 450, 460, and 470 in the secondary particle optical beam path 11.

[0073] The imaging aberrations of the first particle-optical beam path 13 can be largely corrected, resulting in an image that is essentially aberration-free up to the first order and virtually free of distortion aberrations up to the first order. However, with the increasing demand for higher resolution in the range of more precise measurement tasks for the multi-beam particle microscope 1, it has been found that the image plane tilt δ of the beam splitter 400 shown in FIG. 3 frequently accounts for a large portion of the remaining residual aberrations. In FIG. 3, this image plane tilt δ is not drawn to scale. The first individual particle beams 3 impinge on the object or object plane 101 at slightly different heights. In this case, the location of the smallest particle beam diameter is considered to be the focal point. The individual particle beam 3 located exactly on the optical axis A has a focal position exactly on the object plane 101, the first individual particle beam 3 located to the left of it has a focal position located just in front of the object plane 101, and the first individual particle beam 3 located to the right of the axis A has a focal position slightly below the object plane 101. The formation of the field tilt δ is essentially explained by the slightly different path lengths traversed by the plurality of first individual particle beams 3 within the magnet arrangement 400. Investigations by the inventors have shown that previous designs with two magnetic field regions 410 and 430 and a given skew angle β result in the field tilt δ not being able to be compensated for.

[0074] FIG. 4 shows a schematic diagram of the operating parameters for a prior art magnet mechanism 400 having two magnetic field regions 410 and 430 in the primary path 13. The secondary path is not shown in FIG. 4. To ensure a vertical emergence of the primary particle-optical beam path 13 from the first magnetic field region 410 and good imaging characteristics in the objective lens (not shown), the inclination of the emergence point P1 and the emergence region G1 are fixed in the design of the magnetic field mechanism 400, the angle α1 is 90°, and the position in the direction of the Z axis is defined as z1. Therefore, the remaining entrance and exit regions into and out of the magnetic field regions 410 and 430 are available for particle-optical property adaptation. By way of example, points P2, P3, and P4 can be described by their z positions z2, z3, and z4 and by angles α2, α3, and α4. However, other coordinates can, of course, also be chosen to achieve this goal. In principle, the arc lengths S2 and S1 within magnetic field regions 430 and 410, respectively, can be adapted by appropriate selection or definition of points P2, P3, and P4. A drift path 405 is located between points P2 and P3, and the length of the drift path results from the definition of points P2 and P3.

[0075] If point P1 is kept fixed and tilt G1 and the magnetic field strengths in magnetic field regions 410 and 430 are defined, then the system shown in Figure 4 has up to six independent operating parameters: z-positions z2, z3, and z4, and angles α2, α3, and α4. These six operating parameters can be used to optimize the imaging properties of magnet arrangement 400 and reduce aberrations. However, in addition to the aberrations already corrected, complete compensation for path differences, and thus substantial elimination of field tilt, is only possible, if at all, for certain incoming radiation conditions with the arrangement shown in Figure 4.

[0076] Figure 5 is a diagram illustrating the operating parameters for a magnet mechanism 400 having three magnetic field regions 410, 420, and 430 in the primary path 13. Again, the secondary path 11 is not shown in Figure 5 for clarity, but it may correspond to the mechanism shown in Figure 3 with magnetic field regions 450, 460, and 470. Other designs are possible.

[0077] The magnet arrangement 400 in Fig. 5 is of the aligned optical axis type, where the direction of incidence of the primary particle optical beam path 13 into the third magnetic field region 430 and the direction of emergence of the primary particle optical beam path 13 from the first magnetic field region 410 are parallel to each other and have no offset. The direction corresponds to the optical axis A, which in turn corresponds to the optical axis of the objective lens 102 (not shown here). The orientation of the first particle optical beam path 13 upon emergence from the first magnetic field region 410 is defined and shown in Fig. 5 by the angle α1, which is 90°. In other words, the exit tilt of the first magnetic field region 410 is 0°, and the exit region G1 (the letter G indicates "groove") is oriented parallel to the optical axis A and perpendicular to the z-axis. Furthermore, the magnet arrangement 400 specifies that the magnetic field of the first magnetic field region 410 and the magnetic field of the third magnetic field region 430 deflect the primary particle optical beam path 13 in substantially the same direction (in this case, into the plane of the drawing). In this case, the direction of the magnetic field is perpendicular to the z-axis and also to the optical axis A of the objective lens 102 (not shown here). In contrast, the magnetic field in the second magnetic field region 420 is oriented in the opposite direction, so that the first magnetic field region 410 and the second magnetic field region 420 substantially deflect the primary particle optical beam path 13 in different directions.

[0078] To change or define the particle-optical imaging characteristics of the magnet mechanism 400, the magnet mechanism 400, having a fixed point P1 (position and orientation), now includes ten parameters that can be adjusted independently of one another: the z-positions z2, z3, z4, z5, and z6, as well as the angles α2, α3, α4, α5, and α6, which represent measures for the inclination of the grooves G2, G3, G4, G5, and G6. FIG. 5 plots absolute inclination angles. However, it is also possible to define the difference angles of the grooves G1-G6 relative to the horizontal arrangement of the grooves as measures for the inclination. Furthermore, the angles α1-α6 were each selected relative to the field-free region (in this case, the drift paths 405 and 406, or the region outside the magnet mechanism 400). This is because the angles can be plotted directly here. However, these definitions can also be made differently.

[0079] 5, if it is not only the exit point P1 that is defined, but also the entrance point P6 and therefore the entire extent of the magnet arrangement 400 in the z direction, then the number of operating parameters is reduced accordingly. If the tilt α6 is also defined, then there are still eight operating parameters.

[0080] In order to eliminate the image plane tilt induced by the beam splitter, the magnet arrangement 400 according to FIG. 5 may be configured such that there is substantially no path difference for the multiple first individual particle beams 3 when passing through the magnet arrangement 400.

[0081] 6 shows a schematic representation of a magnet arrangement 400 having a plane of symmetry Sy. The primary particle optical beam path 13 or the beam path of the main line is mirror-symmetric with respect to the plane of symmetry Sy as it passes through the magnet arrangement 400. The magnet arrangement 400 includes three magnetic field regions 410, 420, and 430 in the primary path 13 and is symmetrized. The secondary path 11 is not shown in FIG. 6 for clarity. However, the secondary path 11 may be designed as described above in the context of other exemplary embodiments.

[0082] To be precise, the symmetry plane Sy intersects the second magnetic field region 420 centrally. In the symmetrized magnet arrangement 400, the angles α1 and α6 are identical, 90° in the illustrated example. Therefore, the exit tilt of the first magnetic field region 410 is 0° relative to the horizontal, and the same applies to the entrance tilt of the third magnetic field region 430. The angles α2 and α5, as well as α3 and α4, correspond to each other. The z-positions z1 and z6 have the same distance from the symmetry plane Sy, and the same applies to the pairs z2 and z5 and z3 and z4. As a result of the symmetry definition, the magnet arrangement 400 still includes a total of six operating parameters that can be defined independently of each other. This is exactly the same number as in the prior art example shown in FIG. 4. As a result of the more pronounced symmetrization of the magnet arrangement 400, it is possible to reduce or completely compensate for aberrations. To achieve this goal, it may be necessary to make further demands on the symmetry of the primary particle optical beam path 13, for example, with regard to divergence. Each of the first individual particle beams 3 has a divergence D i and enters the magnet assembly 400 with the same divergence, but with the opposite sign, i.e., -D i It may be necessary to eject the magnet assembly 400 again with

[0083] In the illustrated example, the magnetic field strengths of sectors 410 and 430 are set to have the same strength, which contributes to symmetry. The opposing magnetic field strength of second magnetic field region 420 can likewise be chosen to be the same in absolute value.

[0084] The particle-optical mechanism may further comprise a deflector mechanism (not shown in Figure 6) arranged upstream of the third magnetic field region 430 in the direction of the primary particle optical beam path 13 and configured to set the direction of incidence of the primary particle optical beam path 13 into the third magnetic field region 430, and therefore the required incidence tilt, with an accuracy of + / -0.1° or better, in particular with an accuracy of + / -0.05° or better, or + / -0.025° or better, and configured to set the location of incidence of the primary particle optical beam path 13 into the third magnetic field region 430 with an accuracy of + / -0.3 mm or better, in particular with an accuracy of + / -0.1 mm or better, or even with an accuracy of + / -0.05 mm or better. By way of example, the deflector arrangement comprises two adjustment deflectors which can be precisely and independently adjusted to allow setting both the offset and the skew of the first individual particle beam 3 upon entry into the magnet arrangement 400. This prevents possible re-occurrence of beam splitter aberrations, such as field tilt, field astigmatism, global astigmatism or other second or third order aberrations, in case of in-coupling of a skewed or offset beam, which have in fact been previously corrected with the design of the magnet arrangement 400.

[0085] FIG. 7 shows a schematic representation of a further symmetrized magnet arrangement 400 with just four magnetic field regions 410, 420, 440, and 430 in the primary path. Using a total of four magnetic field regions 410, 420, 440, and 430 in the primary particle-optical beam path 13 provides more operational parameters. However, operational parameters are again lost as a result of the symmetry. This magnet arrangement 400 is also of the aligned optical axis type. Angles α1 and α8 are defined, as are positions z1 and z8 or points P1 and P8. Angles α2 and α7, α3 and α6, and α4 and α5 are equal in absolute value. A symmetry plane Sy is located between the second magnetic field region 420 and the fourth magnetic field region 440. Points P4 and P5 have the same distance from the symmetry plane Sy; the same applies to points P3 and P6, P2 and P7, and also to points P1 and P8, or their respective z coordinates. In this case, due to the required symmetry conditions, there are three operational parameters from angles α2, α3, and α4, and three operational parameters from z-positions z2, z3, and z4. In contrast, if both entrance locations P1 and P8 are not simultaneously defined, but rather, for example, only exit location P1 is defined, then an additional operational parameter for the z-position can be obtained. This displaces the position of the symmetry plane Sy, or, in principle, changes the distance between z-positions z4 and z5. Naturally, here, again, even more symmetries can be broken and released; theoretically, as a result of the four parts of the magnet mechanism 400 in the primary path, up to 16 operational parameters can be obtained. Introducing symmetry reduces the number of these operational parameters, but allows for compensation of aberrations. Furthermore, the symmetric design of the magnet mechanism 400 results in the elimination of five second-order aberration terms (out of a total of 18 linearly independent second-order aberration terms). In particular, the field tilt induced by the magnet arrangement 400 can be compensated for or it does not even occur.

[0086] In the case of the symmetrized magnet arrangement 400 shown in FIGS. 6 and 7, the sum of the products of the signed absolute values of the magnetic field strengths, summed over all magnetic field regions 410, 420, 440, and 430 in the primary particle optical beam path 13, and the associated arc lengths in the magnetic field regions 410, 420, 440, and 430 through which the primary particle optical beam path 13 travels is zero. The magnetic field is uniform and typically has no sign. However, the sign is used mathematically to define the direction of the magnetic field. Expressed another way, the sign specifies the direction of the magnetic field relative to a preferred axis perpendicular to the deflection plane in the sense of a vector product. Specifically, in the embodiment shown in FIG. 6, the following sum of products is zero for the central beam: M430*S3+M420*S2+M410*S1=0. Furthermore, the lengths of the drift paths 406 and 405 are identical. Overall, this results in a condition for the aligned optical axis properties of the magnet arrangement 400. The above mentioned condition may not thus apply to the off-axis divergent first individual particle beam 3.

[0087] For the exemplary embodiment shown in FIG. 7, to satisfy the aligned optical axis condition, the following sum of products is 0: M430*S4+M440*S3+M420*S2+M410*S1. Furthermore, drift paths 405 and 407 have the same length, and drift path 406 runs parallel to the z-axis or to the optical axis A (extension of the optical axis of the objective lens). In principle, the length of drift path 406 can be chosen freely and it can be used as a further operating parameter for the target variable to be set.

[0088] Advantageously, the following relationship applies to the separation angle γ by which the primary particle optical beam path 13 is deflected as a whole in the first magnetic field region 410 during operation of the particle-optical mechanism: γ≧2°, preferably γ≧5°, and most preferably γ≧10°.

[0089] Furthermore, it has been found to be advantageous for the total length of the magnet arrangement 400, as defined by the distance between the point of entry (P6, P8) of the primary particle optical beam path 13 into the third magnetic field region 430 and the point of exit P1 of the primary particle optical beam path 13 from the first magnetic field region 410, to be 1.0 m or less, preferably 0.5 m or less, and most preferably 0.3 m or less.

[0090] Furthermore, it is advantageous if the magnet arrangement 400 according to the present invention does not include a beam tube arrangement, through which the primary particle optical beam path 13 extends within the magnet arrangement 400. Instead, the magnet arrangement 400 can have a vacuum chamber, through which the primary particle optical beam path extends within the magnet arrangement 400. Therefore, even when the magnet arrangement 400 is switched off, it is possible to ensure that the first individual particle beam 3 passes through the magnet arrangement 400 or emerges from the magnet arrangement 400 at an exit point P1 that is identical to the exit point P1 when the magnet arrangement 400 is switched on. This facilitates adjustment of the multi-beam particle microscope 1 and is a significant advantage of the aligned optical axis design of the magnet arrangement 400.

[0091] According to an alternative exemplary embodiment, the magnet arrangement 400 nevertheless comprises a beam tube arrangement (not shown here) through which the primary particle optical beam path 13 extends within the magnet arrangement 400, the beam tube arrangement having a torus topology form. As a result, the alignment optical axis properties of the magnet arrangement 400 can be used for adjustment purposes when the primary path beam splitter is switched off or when the magnetic field regions 410, 420, 430, 440 in the primary particle optical beam path 13 are switched off. The torus topology very generally describes two branches of the beam tube arrangement, and when the magnetic field regions 410, 420, 430, 440 are switched off, the primary particle optical beam path 13 can split in a first branch and recombine in a second branch.

[0092] According to a preferred embodiment of the present invention, the following relationship applies to the fill factor F of the beam tube arrangement during operation of the particle-optical arrangement: F≦50%, preferably F≦30%, or most preferably F≦10%. In this case, the fill factor is given as the ratio of the maximum diameter S of the beam (total of the individual particle beams of primary order) to the inner diameter R of the beam tube or beam tube arrangement. In this case, the beam tube is made of a non-magnetic material. For a given maximum diameter S of the beam, the inner diameter R of the beam tube can be appropriately dimensioned. This minimizes contamination of the beam tube as a result of the interaction of the charged particle beam 3, 9 during operation in order to avoid undesired beam deflections due to charged contamination spots inside the beam tube.

[0093] 8 shows a schematic arrangement or alignment of the first magnetic field region 410 in the particle-optical beam path. The exit slope of the exit region or groove G1 from the first magnetic field region 410 is also 0°, as in the previous exemplary embodiment. Therefore, there is a right angle between the exit region or groove G1 and the axis A. If the particle-optical setup is arranged in a multi-beam particle microscope 1, the exit direction from the first magnetic field region 410 corresponds in particular to the direction of the particle-optical axis of the objective lens 102. The secondary particle beam 9, e.g., an electron beam, traveling through the secondary particle-optical beam path 11 during operation of the particle-optical setup typically has a lower kinetic energy than the primary particle beam 3. Therefore, the secondary particles 9 are slower and are deflected more strongly in the first magnetic field region 410, or the trajectory radius r of the trajectory they trace out in a uniform magnetic field. Bis smaller than the corresponding trajectory radius of the faster primary particles 3 or electrons. Therefore, the exit angle σ of the secondary particle optical beam path 11 can, in principle, differ from the incidence angle Φ of the primary beam 3 in the primary particle optical beam path 13, even in the case of orthogonal alignment of the groove G2 with respect to the axis A. The incidence angle Φ and the exit angle σ can be defined by the incidence inclination of the first magnetic field region 410 or the groove G2. In the process, it is advantageous to limit the exit angle σ of the secondary particle optical beam path 11 from this first magnetic field region 410 to σ≦35°, preferably σ≦25° or σ≦15°. This avoids the collection of large aberrations when emerging from the first magnetic field region 410 and creates additional installation space for possible additional secondary path magnetic field regions in the gap between the first magnetic field region 410 and the second magnetic field region 420. According to a further exemplary embodiment, at least one of the further magnetic field regions of the secondary particle optical beam path 11 is arranged in the gap between the first magnetic field region 410 and the second magnetic field region 420 of the primary particle optical beam path 13.

[0094] By way of example, the magnet arrangement 400 can have at least two further magnetic field regions in the secondary particle optical beam path 11 after passing through the first magnetic field region 410, which are configured to precisely couple the particle optical axis Z in the secondary beam path 11 into the downstream projection optical unit 200 (see, e.g., FIG. 1 ) with respect to offset and angle when the energy of the secondary particles whose paths form the second particle optical beam path 11 is variable. By way of example, a change in the energy of the secondary particles 9 can be the result of changing the landing energy setting.

[0095] According to an exemplary embodiment, the magnet mechanism 400 has at least six further magnetic field regions and / or quadrupole fields in the secondary particle optical beam path 11 after passing through the first magnetic field region 410, and the at least six further magnetic field regions and / or quadrupole fields are configured to precisely couple the particle optical axis Z in the secondary beam path 1 into the downstream projection optical unit 200 (e.g., see Figure 1) in terms of offset and angle when the energy of the secondary particles 9 whose path forms the second particle optical beam path 11 is variable, and in addition to that enable imaging that is paraxial aberration-free, has no paraxial distortion aberration, and has no paraxial dispersion.

[0096] According to a further exemplary embodiment, the magnet arrangement 400 further comprises a magnetic shielding wall arranged between at least one of the magnetic field regions 410, 420, 430, 440 of the primary particle optical beam path 13 and at least one of the magnetic field regions of the secondary particle optical beam path 11. Of course, it may also be arranged substantially continuously between all of the magnetic field regions 410, 420, 430, 440 of the primary particle optical beam path 13 and all of the magnetic field regions of the secondary particle optical beam path 11. By way of example, the magnetic shielding wall comprises a web of soft magnetic material which minimizes crosstalk between the primary and secondary path magnetic field regions.

[0097] According to a further exemplary embodiment, the magnetic shielding wall has an open channel through which the first particle-optical beam path passes linearly along the particle-optical axis when the magnet mechanism is switched off. As a result, the alignment optical axis characteristics of the magnet mechanism when the magnetic field region of the primary path is switched off can be used for adjustment purposes. The open channel can be characterized by a ratio K of the channel length L to the channel width B. For example, if K≧3, preferably K≧5 or K≧10, magnetic shielding between the magnetic field regions of the primary and secondary paths is well ensured despite the open channel.

[0098] The magnet arrangement 400 according to the invention, like the magnet arrangement 400 according to the prior art, can also be integrated into a multi-beam particle microscope 1, for example within the one shown diagrammatically in FIG.

[0099] According to exemplary embodiments, the imaging of the first individual particle beams 3 onto the object plane 101 exhibits substantially no image plane tilt. Naturally, as already explained in detail above, it is also possible to correct other imaging aberrations through a suitable design of the magnet arrangement 400. According to exemplary embodiments, the imaging of the first individual particle beams 3 into the object plane 101 as a whole has substantially no distortion aberrations, and / or the imaging of the first individual particle beams 3 into the object plane 101 has substantially no dispersion, and / or the incidence locations 5 of the first individual particle beams 3 in the object plane 101 have astigmatism and are circular. Additionally or alternatively, it is also possible to correct other aberrations in the field of particle-optical imaging. Depending on the design, the magnet arrangement 400 according to the present invention also provides suitable operating parameters for the purpose of correction. Correction may also include correction of sample skew and / or correction of focal tilt as a result of misalignment of the illumination system / condenser lens system.

[0100] According to an exemplary embodiment, the imaging of the first individual particle beam 3 into the object plane 101 has no field astigmatism. In addition, it may apply that the sum of all other aberrations of second and third order in the object plane 101 is no more than 1 nm, preferably no more than 0.5 nm or no more than 0.25 nm.

[0101] Further exemplary embodiments are listed below. Example 1. A particle-optical arrangement for providing a primary particle-optical beam path for a plurality of first individual particle beams emanating from a multi-beam particle generator and directed toward an object positionable in an object plane of the arrangement, and a secondary particle-optical beam path for a plurality of second individual particle beams emanating from the object, comprising: The particle-optical mechanism comprises a magnet mechanism, a first magnetic field region through which the primary particle-optical beam path and the second particle-optical beam path pass, for separating the primary particle-optical beam path and the second particle-optical beam path from each other; a second magnetic field region disposed in the primary particle optical beam path and not in the secondary particle optical beam path, the second magnetic field region being disposed upstream of the first magnetic field region with respect to the primary particle optical beam path, the first magnetic field region and the second magnetic field region substantially deflecting the primary particle optical beam path in different directions; a third magnetic field region disposed in the primary particle optical beam path and not in the secondary particle optical beam path, the third magnetic field region being disposed upstream of the second magnetic field region with respect to the primary particle optical beam path, the first and third magnetic field regions substantially deflecting the primary particle optical beam path in the same direction; Including, A particle-optical arrangement, wherein the direction of incidence of the primary particle-optical beam path into the third magnetic field region and the direction of emergence of the primary particle-optical beam path from the first magnetic field region are substantially parallel to each other and have substantially no offset. Example 2. A first drift region substantially free of a magnetic field is disposed in the primary particle optical beam path between the first magnetic field region and the second magnetic field region; and / or 2. The particle-optical setup of example 1, wherein a second drift region substantially free of a magnetic field is disposed in the primary particle-optical beam path between the second magnetic field region and the third magnetic field region. Example 3. A magnet arrangement having a fourth magnetic field region disposed in the primary particle optical beam path and not disposed in the secondary particle optical beam path; a fourth magnetic field region disposed upstream of the second magnetic field region and downstream of the third magnetic field region with respect to the primary particle optical beam path; 2. The particle-optical setup of example 1, wherein the fourth magnetic field region and the second magnetic field region substantially deflect the primary particle-optical beam path in the same direction. Example 4. A first drift region substantially free of a magnetic field is disposed in the primary particle optical beam path between the first magnetic field region and the second magnetic field region; and / or a second drift region substantially free of a magnetic field is disposed in the primary particle optical beam path between the second magnetic field region and the fourth magnetic field region; and / or 4. The particle-optical setup of example 3, wherein a third drift region substantially free of a magnetic field is disposed in the primary particle-optical beam path between the fourth magnetic field region and the third magnetic field region. Example 5. A particle-optical arrangement according to any one of Examples 1 to 4, wherein the magnet arrangement does not have an additional magnetic field region in the primary particle-optical beam path designed to deflect the primary particle-optical beam path by more than 2°, in particular 1°, or 0.5°. Example 6. The particle-optical arrangement of any one of Examples 1 to 5, wherein the magnet arrangement is configured such that there is substantially no path difference for the plurality of first individual particle beams as they pass through the magnet arrangement. Example 7. A particle-optical arrangement according to any one of Examples 1 to 6, wherein the magnet arrangement has a plane of symmetry, and the primary particle-optical beam path is mirror symmetric with respect to the plane of symmetry as it passes through the magnet arrangement. Example 8. The particle-optical setup of Examples 3 and 7, wherein the plane of symmetry intersects the second magnetic field region. Example 9. The particle-optical setup of Examples 5 and 7, wherein the plane of symmetry is located between the second magnetic field region and the fourth magnetic field region. Example 10. A particle-optical mechanism according to any one of Examples 1 to 9, wherein the direction of the magnetic field in all of the magnetic field regions of the magnet mechanism is substantially perpendicular to the optical axis of the primary particle-optical beam path during operation of the particle-optical mechanism, and the magnetic field is substantially uniform. Example 11. The uniform magnetic fields in the magnetic field region in the primary particle optical beam path each have an absolute value of the magnetic field strength during operation of the particle optical mechanism, and the magnetic fields are each assigned a sign, the sign characterizing the direction of the magnetic field; 11. The particle-optical setup of example 10, wherein a sum of the signed absolute value of the product of the magnetic field strength, summed over all magnetic field regions in the primary particle-optical beam path, and the associated arc length in the magnetic field region along which the primary particle-optical beam path travels in the magnetic field region is substantially zero. Example 12. A particle-optical mechanism according to any one of Examples 1 to 11, wherein the following relationship applies to the separation angle γ by which the primary particle-optical beam path is deflected as a whole in the first magnetic field region during operation of the particle-optical mechanism: γ≧2°, in particular γ≧5° or γ≧10°. Example 13. A particle-optical arrangement according to any one of Examples 1 to 12, wherein the total length of the magnet arrangement, as defined by the distance between the point of entry of the primary particle-optical beam path into the third magnetic field region and the point of exit of the primary particle-optical beam path from the first magnetic field region, is equal to or less than 1.0 m, in particular equal to or less than 0.5 m and / or equal to 0.3 m. Example 14. Each magnetic field region has an entrance region for a primary particle optical beam path with an entrance gradient and an exit region for a primary particle optical beam path with an exit gradient; Incident tilt is defined as the angle by which the alignment of the incident field deviates from the normal to the optical axis of the primary particle optical beam path; the exit tilt is defined as the angle by which the alignment of the exit region deviates from the normal to the optical axis of the primary particle optical beam path; A particle-optical setup according to any one of Examples 1 to 13, wherein the first magnetic field region has an exit tilt of 0°. Example 15. The particle-optical setup of example 14, wherein the third magnetic field region has an incident tilt of 0°. Example 16. The particle-optical arrangement of any one of Examples 1 to 15, wherein the magnet arrangement does not include a beam tube arrangement in which the primary particle-optical beam path extends within the magnet arrangement. Example 17. The particle-optical arrangement of example 16, wherein the magnet arrangement comprises a vacuum chamber through which the primary particle-optical beam path extends within the magnet arrangement. Example 18. The intermediate images of the first individual particle beams are not located in the primary particle optical beam path in the magnet arrangement, and / or 18. The particle-optical setup of any one of examples 1-17, wherein no crossovers between the plurality of first individual particle beams are formed in the primary particle-optical beam path in the magnet setup. Example 19. The particle-optical arrangement of any one of Examples 1 to 18, wherein the magnet arrangement has at least one further magnetic field region in the secondary particle-optical beam path. Example 20. The particle-optical setup is a multi-beam particle microscope, and the particle-optical setup comprises: a multi-beam particle generator configured to generate a first field of a plurality of charged first individual particle beams; a first particle-optical unit having a primary particle-optical beam path configured to image the generated first individual particle beam onto an object plane such that the first individual particle beam impinges on the object at an incidence location that forms a second field of view; a detection unit having a plurality of detection areas forming a third field of view; a second particle-optical unit having a secondary particle-optical beam path configured to image a second individual particle beam emanating from an incidence location within the second field of view onto a third field of view of a detection region of the detection system; a magnetic and / or electrostatic objective lens through which both the first and second individual particle beams pass; a controller configured to control particle-optical components in the primary particle-optical beam path and / or the secondary particle-optical beam path and / or components of the magnet arrangement; and 20. The particle-optical mechanism of any one of Examples 1 to 19, wherein the magnet mechanism is disposed in a primary particle-optical beam path between the multi-beam particle generator and the objective lens, and the magnet mechanism is disposed in a secondary particle-optical beam path between the objective lens and the detection unit. Example 21. The particle-optical setup of example 20, wherein the imaging of the plurality of first individual particle beams onto the object plane exhibits substantially no image plane tilt. Example 22. Imaging of the plurality of first individual particle beams into the object plane as a whole is substantially free of distortion, and / or the imaging of the first individual particle beams into the object plane has substantially no dispersion, and / or 22. The particle-optical setup of embodiment 20 or 21, wherein the locations of incidence of the individual particle beams in the object plane are astigmatic and circular. [Explanation of symbols]

[0102] 1. Multibeam particle microscope 3 Primary particle beams (individual particle beams) 5 Beam spot, incident point 7 Objects, Samples 9 Secondary particle beam 10 Computer system, controller 11 Secondary particle optical beam path 13 Primary particle optical beam path 15 Sample surface 101 Object plane 102 Objective Lens 105 axes 200 detector system 205 Projection Lens System 209 Detection system, particle multi-detector, detection unit 210 Lens 220 Lens 222 contrast aperture 260 Scan Prevention 300 Beam Generator 301 Particle Source 303 Collimation Lens System 305 Multi-aperture mechanism 306 Micro-Optical Elements 307 Field Lens 308 Field Lens 309 Diverging Particle Beam 323 Beam Focus 325 Intermediate image plane 400 Beam splitter, magnet mechanism 405 Drift Path 406 Drift Path 407 Drift Path 410 Magnetic Field Region 420 Magnetic Field Region 430 Magnetic Field Region 440 Magnetic Field Region 450 magnetic field region 460 Magnetic Field Region 461 Beam tube mechanism limbs 462 Beam Tube Mechanism Limbs 463 Beam Tube Mechanism Limbs 466 Junction 470 Magnetic Field Region 490 Beam Tube Mechanism 500 scanning deflector 600 Displacement table or positioning device A-axis z1…z8 z position α1…α8 Inclination angle β Skew angle γ separation angle δ Image plane tilt angle σ Output angle Φ Incident angle G1...G8 Magnetic field area edges, grooves, depressions P1…P8 points, positions S1…S4 Arc length Sy symmetry plane

Claims

1. 1. A particle-optical arrangement for providing a primary particle-optical beam path for a plurality of first individual particle beams emanating from a multi-beam particle generator and directed towards an object positionable in an object plane of the arrangement, and a secondary particle-optical beam path for a plurality of second individual particle beams emanating from the object, comprising: The particle-optical mechanism includes a magnet mechanism, and the magnet mechanism a first magnetic field region through which the primary particle optical beam path and the secondary particle optical beam path pass, for separating the primary particle optical beam path and the secondary particle optical beam path from each other; a second magnetic field region disposed in the primary particle optical beam path and not in the secondary particle optical beam path, the second magnetic field region being disposed upstream of the first magnetic field region with respect to the primary particle optical beam path, the first magnetic field region and the second magnetic field region substantially deflecting the primary particle optical beam path in different directions; a third magnetic field region disposed in the primary particle optical beam path and not in the secondary particle optical beam path, the third magnetic field region being disposed upstream of the second magnetic field region with respect to the primary particle optical beam path, the first and third magnetic field regions substantially deflecting the primary particle optical beam path in the same direction; Including, A particle-optical setup, wherein the direction of incidence of the primary particle-optical beam path into the third magnetic field region and the direction of emergence of the primary particle-optical beam path from the first magnetic field region are parallel to each other and have no offset.

2. a first drift region substantially free of a magnetic field is disposed in the primary particle optical beam path between the first magnetic field region and the second magnetic field region; and / or 2. The particle-optical setup of claim 1, wherein a second drift region substantially free of a magnetic field is disposed in the primary particle-optical beam path between the second magnetic field region and the third magnetic field region.

3. the magnet mechanism has a fourth magnetic field region disposed in the primary particle optical beam path and not disposed in the secondary particle optical beam path; the fourth magnetic field region is disposed upstream of the second magnetic field region and downstream of the third magnetic field region with respect to the primary particle optical beam path; The particle-optical setup of claim 1 , wherein the fourth magnetic field region and the second magnetic field region substantially deflect the primary particle-optical beam path in the same direction.

4. a first drift region substantially free of a magnetic field is disposed in the primary particle optical beam path between the first magnetic field region and the second magnetic field region; and / or a second drift region substantially free of a magnetic field is disposed in the primary particle optical beam path between the second magnetic field region and the fourth magnetic field region; and / or 4. The particle-optical setup of claim 3, wherein a third drift region substantially free of a magnetic field is disposed in the primary particle-optical beam path between the fourth magnetic field region and the third magnetic field region.

5. 5. The particle-optical arrangement according to claim 1, wherein the magnet arrangement has no further magnetic field regions in the primary particle-optical beam path designed to deflect the primary particle-optical beam path by more than 2°, in particular by more than 1°, or by more than 0.5°.

6. 6. The particle-optical arrangement according to claim 1, wherein the magnet arrangement is configured such that there are substantially no path differences for the plurality of first individual particle beams as they pass through the magnet arrangement.

7. A particle-optical arrangement according to any one of claims 1 to 6, wherein the magnet arrangement has a plane of symmetry, and the primary particle-optical beam path is mirror-symmetric with respect to the plane of symmetry as it passes through the magnet arrangement.

8. A particle-optical setup according to claims 3 and 7, wherein the plane of symmetry intersects the second magnetic field region.

9. 8. A particle-optical setup according to claims 5 and 7, wherein the plane of symmetry is located between the second magnetic field region and the fourth magnetic field region.

10. 10. The particle-optical mechanism according to claim 1, wherein the direction of the magnetic field in all of the magnetic field regions of the magnet mechanism is substantially perpendicular to the optical axis of the primary particle-optical beam path during operation of the particle-optical mechanism, and the magnetic field is substantially uniform.

11. the uniform magnetic fields in the magnetic field region in the primary particle-optical beam path each have an absolute value of the magnetic field strength during the operation of the particle-optical mechanism, the magnetic fields each being assigned a sign, the sign characterizing the direction of the magnetic field; 11. The particle-optical setup of claim 10, wherein the sum of the products of the signed absolute values of the magnetic field strengths, summed over all magnetic field regions in the primary particle optical beam path, and the associated arc lengths within the magnetic field region that the primary particle optical beam path traverses within the magnetic field region is substantially zero.

12. 12. The particle-optical arrangement according to claim 1, wherein the following relationship applies to a separation angle γ, by which the primary particle-optical beam path is deflected as a whole in the first magnetic field region during the operation of the particle-optical arrangement: γ≧2°, in particular γ≧5° or γ≧10°.

13. 13. The particle-optical arrangement according to any one of claims 1 to 12, wherein the total length of the magnet arrangement, as defined by the distance between the point of entry of the primary particle optical beam path into the third magnetic field region and the point of exit of the primary particle optical beam path from the first magnetic field region, is 1.0 m or less, in particular 0.5 m or less or 0.3 m or less.

14. each magnetic field region having an entrance region for the primary particle optical beam path having an entrance gradient and an exit region for the primary particle optical beam path having an exit gradient; the incidence tilt is defined as the angle by which the alignment of the incidence region deviates from normal to the optical axis of the primary particle optical beam path; the exit tilt is defined as the angle by which the alignment of the exit region deviates from the normal to the optical axis of the primary particle optical beam path; A particle-optical setup according to any one of claims 1 to 13, wherein the exit tilt of the first magnetic field region is 0°.

15. 15. The particle-optical setup of claim 14, wherein the incidence tilt of the third magnetic field region is 0[deg.].

16. 1. A particle-optical arrangement comprising: a deflector mechanism arranged upstream of the third magnetic field region in the direction of the primary particle optical beam path and configured to set the entrance direction, and therefore the entrance tilt, of the primary particle optical beam path into the third magnetic field region with an accuracy of + / - 0.1° or better, in particular with an accuracy of + / - 0.05° or better, or with an accuracy of + / - 0.025° or better, and configured to set the entrance location of the primary particle optical beam path into the third magnetic field region with an accuracy of + / - 0.3 mm or better, in particular with an accuracy of + / - 0.1 mm or better, or even with an accuracy of + / - 0.05 mm or better.

17. 17. The particle-optical arrangement according to any one of claims 14 to 16, wherein the incidence tilt of the first magnetic field region is selected such that the exit angle σ of the secondary particle optical beam path from this first magnetic field region is limited to σ≦35°, in particular σ≦25° or σ≦15°.

18. 18. The particle-optical setup according to any one of claims 1 to 17, wherein the magnet setup comprises a beam tube setup through which the primary particle-optical beam path extends within the magnet setup, the beam tube setup having a torus topological form.

19. 19. Particle-optical setup according to claim 18, wherein the following relationship applies to the fill factor F of the beam tube setup during operation of the particle-optical setup: F≦50%, in particular F≦30% or F≦10%.

20. Particle-optical set-up according to any one of claims 1 to 17, wherein the magnet set-up does not include a beam tube set-up through which the primary particle-optical beam path extends within the magnet set-up.

21. 21. The particle-optical setup of claim 20, wherein the magnet setup includes a vacuum chamber through which the primary particle-optical beam path extends within the magnet setup.

22. Particle-optical set-up according to any one of claims 1 to 21, wherein the magnet set-up has at least one further magnetic field region in the secondary particle-optical beam path.

23. 23. The particle-optical arrangement of claim 22, wherein the magnet arrangement has at least two further magnetic field regions in the secondary beam path after the passage of the first magnetic field region, the at least two further magnetic field regions configured to precisely couple the particle-optical axis in the secondary beam path into a downstream projection optical unit with respect to offset and angle when the energy of secondary particles whose paths form the second particle-optical beam path is variable.

24. 23. The particle-optical setup according to claim 22, wherein the magnet setup comprises at least six further magnetic field regions and / or quadrupole fields in the secondary beam path after the passage of the first magnetic field region, the at least six further magnetic field regions and / or quadrupole fields being configured to precisely couple the particle-optical axis in the secondary beam path into a downstream projection optical unit with respect to offset and angle when the energy of secondary particles whose paths form the second particle-optical beam path is variable, and additionally to enable paraxial aberration-free, paraxial distortion-free and paraxial dispersion-free imaging.

25. 25. A particle-optical setup according to any one of claims 22 to 24, wherein at least one of the further magnetic field regions of the secondary particle optical beam path is arranged in a gap between the first and second magnetic field regions of the primary particle optical beam path.

26. 26. The particle-optical setup according to any one of claims 22 to 25, further comprising a magnetic shielding wall arranged between at least one of the magnetic field regions of the primary particle optical beam path and at least one of the magnetic field regions of the secondary particle optical beam path.

27. 27. The particle-optical arrangement of claim 26, wherein the magnetic shielding wall has an open channel through which the first particle-optical beam path passes linearly along the particle-optical axis when the magnet arrangement is switched off.

28. The particle-optical setup is a multi-beam particle microscope, and the particle-optical setup comprises: a multi-beam particle generator configured to generate a first field of a plurality of charged first individual particle beams; a first particle-optical unit having a primary particle-optical beam path configured to image the generated first individual particle beam onto an object plane such that the first individual particle beam impinges on an object at an incidence location that forms a second field of view; a detection unit having a plurality of detection areas forming a third field of view; a second particle-optical unit having a secondary particle-optical beam path configured to image a second individual particle beam emanating from the incidence location within the second field of view onto the third field of view of the detection area of the detection system; a magnetic and / or electrostatic objective lens through which both the first and second individual particle beams pass; a controller configured to control particle-optical components in the primary particle-optical beam path and / or the secondary particle-optical beam path and / or components of the magnet arrangement; and 28. The particle-optical setup according to any one of claims 1 to 27, wherein the magnet setup is arranged in the primary particle-optical beam path between the multi-beam particle generator and the objective lens, and the magnet setup is arranged in the secondary particle-optical beam path between the objective lens and the detection unit.

29. 30. The particle-optical setup of claim 28, wherein the imaging of the plurality of first individual particle beams onto the object plane exhibits substantially no image plane tilt.

30. the imaging of the plurality of first individual particle beams into the object plane is substantially distortion-free overall; and / or the imaging of the first individual particle beam into the object plane has substantially no dispersion, and / or 30. A particle-optical setup according to claim 28 or 29, wherein the location of incidence of the first individual particle beam in the object plane is astigmatic and circular.

31. A particle-optical setup according to any one of claims 28 to 30, wherein the imaging of the first individual particle beam into the object plane is free of field astigmatism.

32. 32. A particle-optical setup according to claim 31, wherein the sum of all other second and third order aberrations in the object plane is no more than 1 nm, in particular no more than 0.5 nm or no more than 0.25 nm.

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