Particle optical arrangement, in particular a multi-beam particle microscope, with a magnetic arrangement for separating a primary and a secondary particle optical beam path with improved performance

Abstract

A particle-optical arrangement is disclosed for providing a primary particle-optical beam path for a plurality of first single-particle beams directed from a multi-beam particle generator onto an object positionable in an object plane of the arrangement, as well as a secondary particle-optical beam path for a plurality of second single-particle beams emanating from the object. The particle-optical arrangement includes a magnetic array comprising a first magnetic field region traversed by the primary and secondary particle-optical beam paths to separate them.The magnetic arrangement further comprises a second magnetic field region, which is located in the primary particle optical beam path and not in the secondary particle optical beam path. The second magnetic field region is located in front of the first magnetic field region with respect to the primary particle optical beam path, and the first and second magnetic field regions deflect the primary particle optical beam path in different directions. The first magnetic field region has an exit inclination σ1 ≠ 0°, where the exit inclination σ1 is defined as the angle by which the orientation of the exit region deviates from the orthogonal to the particle optical axis Z of the primary particle optical beam path.

Description

Field of the invention

[0001] The invention relates to a particle-optical arrangement with an improved beam splitter. Specifically, the invention relates to a particle-optical arrangement, and in particular to a multi-beam particle microscope with a magnet arrangement for separating a primary particle-optical beam path and a secondary particle-optical beam path with improved performance. State of the art

[0002] With the continuous development of ever smaller and more complex microstructures such as semiconductor devices, there is a need for the further development and optimization of planar manufacturing techniques and inspection systems for the production and inspection of small dimensions of microstructures. For example, the development and manufacture of semiconductor devices requires verification of the design of test wafers, and planar manufacturing techniques require process optimization for reliable, high-throughput manufacturing. Furthermore, there is a recent demand for semiconductor wafer analysis for reverse engineering and customized, individual configuration of semiconductor devices. Therefore, there is a need for inspection tools that can be used at high throughput to examine microstructures on wafers with high accuracy.

[0003] Typical silicon wafers used in the manufacture of semiconductor devices have diameters of up to 300 mm. Each wafer is divided into 30 to 60 repeating regions (“dies”) with a size of up to 800 mm. 2A semiconductor device comprises several semiconductor structures that are manufactured in layers on a wafer surface using planar integration techniques. Due to the manufacturing processes, semiconductor wafers typically have a flat surface. The feature size of the integrated semiconductor structures ranges from a few µm up to the critical dimensions (CD) of 5 nm, with feature sizes set to become even smaller in the near future; feature sizes or critical dimensions (CD) of less than 3 nm, for example 2 nm, or even less than 1 nm are expected in the future. With the small feature sizes mentioned above, defects the size of the critical dimensions must be identified over a very large area in a short time.For several applications, the specification requirement for the accuracy of a measurement provided by an inspection device is even higher, for example, by a factor of two or an order of magnitude. For example, a semiconductor feature width must be measured with an accuracy of less than 1 nm, such as 0.3 nm or even less, and a relative position of semiconductor structures must be determined with an overlay accuracy of less than 1 nm, such as 0.3 nm or even less.

[0004] A recent development in the field of charged particle microscopes (CPM) is the MSEM, a multi-beam scanning electron microscope. A multi-beam scanning electron microscope is disclosed, for example, in US Pat. No. 7,244,949 B2 and US Pat. No. 2019 / 0355544 A1. In a multi-beam electron microscope, or MSEM, a sample is simultaneously irradiated with a plurality of individual electron beams arranged in a field or grid. For example, 4 to 10,000 individual electron beams can be provided as primary radiation, with each individual electron beam separated from a neighboring individual electron beam by a distance of 1 to 200 micrometers. For example, an MSEM has approximately 100 separate single electron beams (beamlets), arranged in a hexagonal grid, for example, with the single electron beams separated by a distance of approximately 10 µm.The plurality of charged single-particle beams (primary beams) are focused by a common objective lens onto the surface of a sample under investigation. The sample can be, for example, a semiconductor wafer attached to a wafer holder mounted on a movable stage. During illumination of the wafer surface with the charged primary single-particle beams, interaction products, such as secondary electrons or backscattered electrons, emanate from the wafer surface. Their starting points correspond to the locations on the sample on which the plurality of primary single-particle beams are focused. The quantity and energy of the interaction products depend on the material composition and the topography of the wafer surface.The interaction products form multiple secondary single-particle beams (secondary beams), which are collected by the common objective lens and projected by a projection imaging system of the multi-beam inspection system onto a detector arranged in a detection plane. The detector comprises multiple detection regions, each of which can comprise multiple detection pixels, and the detector records an intensity distribution for each of the secondary single-particle beams. This results in an image field of, for example, 100 µm × 100 µm.

[0005] The prior art multi-beam electron microscope comprises a sequence of electrostatic and magnetic elements. At least some of the electrostatic and magnetic elements are adjustable to adjust the focus position and stigma of the plurality of charged single-particle beams. The prior art multi-beam charged particle system further comprises at least one crossover plane of the primary or secondary charged single-particle beams. Furthermore, the prior art system comprises detection systems to facilitate adjustment. The prior art multi-beam particle microscope comprises at least one beam deflector (deflection scanner) for collectively scanning a region of the sample surface using the plurality of primary single-particle beams to obtain an image field of the sample surface.

[0006] To separate the particle-optical beam path of the primary beams from the particle-optical beam path of the secondary beams, a so-called beam splitter (also known as a "beam separator" or "beam divider") is used. Separation is achieved using special arrangements of magnetic and / or electrostatic fields, for example, a Wien filter.

[0007] The use of particle-optical components generally results in aberrations. These include, for example, field curvature and field astigmatism. The use of a beam splitter also results in aberrations in particle-optical images, which must be corrected if possible. Ideally, aberrations should be avoided or corrected for all individual particle beams. The corrections are generally more important the larger the image fields of the particle-optical images are. In multi-beam particle microscopes, which operate with a large number of individual particle beams, an image field can be particularly extensive (multi-field of view, so-called mFOV). This is all the more true since multi-beam particle microscopes operate with an increasing number of individual particle beams, which further enlarges the image field.

[0008] As imaging quality demands increase, so do the requirements for the multibeam particle microscope used for imaging. For example, to achieve very good resolution in a multibeam particle microscope, field curvature in the object plane must be minimized. The first measure is to optimize the electron optics or the charged particle optics of the multibeam particle microscope. As a second measure, the state of the art proposes the use of active devices for individual beam correction, and in particular, for focal length adjustment for each beam.

[0009] Optimizing electron optics as part of the first step also includes optimizing beam splitters. To correct aberrations in beam splitters of multi-beam particle microscopes, it is known from EP 1 668 662 B1 to provide 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. According to EP 1 668 662 B1, it is possible to correct first-order aberrations in both the primary and secondary paths. However, with increasing resolution requirements, it is becoming increasingly necessary to correct higher-order aberrations as well.

[0010] An active correction device is known from US Pat. No. 9,153,413 B2. This device discloses another beam splitter for multi-beam particle microscopes, which corrects beam splitter-induced aberrations. The beam splitter operates according to the Wien filter principle. To correct aberrations, the alignments or tilts of individual particle beams are corrected individually using multi-deflector arrays after passing through the beam splitter.

[0011] Furthermore, the prior art proposes the use of active devices for individual focal length adjustment per beam, e.g., arrays of individually addressable ring electrodes as the active parts of micro-lens arrays. The focal length of a single micro-lens is approximately quadratically dependent on the voltage applied to the respective lens electrode. However, these active devices for correcting the field curvature per individual particle beam are difficult to produce and expensive. It is essential that each individual micro-correction device functions perfectly; otherwise, this type of correction device is not practical.Furthermore, it is challenging, for example, to supply each micro-lens array with a voltage on the order of more than 50 V, more than 100 V, or even more than 400 V. This poses serious isolation problems, and current active correction devices have a very limited lifetime. Examples of active correction devices can be found in, for example, US 5,834,783 A, US 6,483,120 B1, US 6,903,353 B2, US 7,126,141 B2, and US 11,145,485 B2.

[0012] Especially with the use of ever-increasing numbers of single-particle beams and thus ever-larger image fields, the active correctors described above are reaching their limits. It is therefore desirable to further improve the electron optics themselves. This includes further improving the beam switch. This could also limit the requirements for additional active correction elements.

[0013] DE 35 32 698 A1 describes an alpha-type electron energy filter intended for use in a transmission electron microscope (TEM). The disclosed electron energy filter is a dispersive energy filter with a symmetrical structure and consists of three deflection regions separated from each other by gaps. DE 35 32 698 A1 discloses that edge inclinations of the magnetic sectors relative to the wavefront can be advantageous, and corresponding regions are specified.

[0014] DE 101 07 910 A1 discloses a particle beam system, such as a scanning electron microscope, that has a mirror corrector. The mirror corrector comprises an electrostatic mirror and a magnetic deflector consisting of five sectors. The lowest or last sector is a splitting sector. The magnetic deflector is generally straight-sighted and dispersion-free. Furthermore, the influence of trench inclinations on the focusing effect of the magnet arrangement is disclosed in DE 101 07 910 A1. An exit trench of the splitting sector is not inclined.

[0015] DE 35 32 699 A1 discloses an omega-type electron energy filter. Here, too, the edges of the magnetic sectors are inclined, and the overall arrangement is symmetrical.

[0016] US Pat. No. 7,244,949 B2 discloses a beam splitter with a total of three magnetic sectors in the secondary path. The bottom trench of the splitting sector is not inclined. Description of the invention

[0017] It is therefore an object of the invention to provide a particle-optical arrangement and in particular a multi-beam particle microscope by means of which beam switch-induced aberrations occurring in particular in the primary path can be corrected even better.

[0018] A particular object of the invention is to further reduce field tilt and field astigmatism. At the same time, other second-order and higher aberrations should not be magnified.

[0019] The problem is solved by the subject matter of the independent patent claim.

[0020] Advantageous embodiments of the invention emerge from the dependent patent claims.

[0021] The aberrations that can typically occur in multi-beam particle microscopes include, for example, spherical aberrations, astigmatism, coma, field curvature, distortion, chromatic aberrations or dispersion, etc. In the multi-beam particle microscope described in EP 1 668 662 B1 with the beam splitter already briefly described above or the described arrangement of magnetic sector fields or magnetic field regions, images of the plurality of first individual particle beams in the object plane can essentially already be essentially stigmatic in the first order and essentially distortion-free in the first order, and also dispersion-free.

[0022] An objective of the present invention is to further improve the performance of the already known beam switch and thus the performance of multi-beam particle beam systems and in particular multi-beam particle microscopes in general.

[0023] For this purpose, the aberrations induced by the known beam splitter were investigated in more detail, with high-precision measurements being carried out to create a so-called focus map. It turned out that the remaining leading residual error in particle-optical imaging is often not the field curvature at all, but the field tilt. With field tilt, the focus position of the first individual particle beams relative to the (ideal) object plane changes linearly with the distance from the optical axis. With field curvature, however, the focus position changes quadratically with the distance from the optical axis. Several compensators have already been proposed in DE 10 2021 200 799 B3 to correct field tilt.

[0024] Field tilt is a non-rotationally symmetric aberration, unlike, for example, field curvature. One cause of non-rotationally symmetric aberrations in existing beam splitters is a symmetry break in the beam splitters. A skew angle between the optical axis at the point where the primary rays enter the beam splitter and the optical axis at the point where the primary rays exit the beam splitter can contribute to this symmetry break. Therefore, one possible approach is to modify the design of the beam splitter itself and place at least one additional magnetic field region in the primary path, eliminating the tilt angle. This, however, requires further system modifications.

[0025] The present invention therefore takes a different approach. The basic design of the beam splitter or magnet arrangement with only two sectors or magnetic field regions in the primary path is to be retained. At the same time, however, the beam splitter-induced aberrations are to be further reduced. During investigations within the scope of the invention, a completely non-intuitive solution has surprisingly emerged that allows for the essential elimination or drastic reduction of leading second-order aberrations, namely field tilt and field astigmatism, with only two magnetic field regions in the primary path. At the same time, other aberrations are essentially not magnified.

[0026] According to a first aspect of the invention, this relates to a particle-optical arrangement for providing a primary particle-optical beam path for a plurality of charged first single-particle beams, which are directed from a multi-beam particle generator onto an object positionable in an object plane of the arrangement, and a secondary particle-optical beam path for a plurality of charged second single-particle beams, which emanate from the object, wherein the particle-optical arrangement comprises a magnet arrangement comprising: a first magnetic field region traversed by the primary particle-optical beam path and the secondary particle-optical beam path to separate the primary particle-optical beam path and the secondary particle-optical beam path from each other; a second magnetic field region arranged in the primary particle-optical beam path and not arranged in the secondary particle-optical beam path, wherein the second magnetic field region is arranged in front of the first magnetic field region with respect to the primary particle-optical beam path, and wherein the first magnetic field region and the second magnetic field region deflect the primary particle-optical beam path in different directions; wherein each magnetic field region has an entrance region for the primary particle-optical beam path with an entrance inclination φ and an exit region for the primary particle-optical beam path with an exit inclination σ, where the entrance inclination φ is defined as the angle by which the orientation of the entrance area deviates from the orthogonal to the particle-optical axis Z of the primary particle-optical beam path, and where the exit inclination σ is defined as the angle by which the orientation of the exit area deviates from the orthogonal to the particle-optical axis Z of the primary particle-optical beam path, and where the exit inclination σ1 of the first magnetic field region deviates from 0°.

[0027] The exit inclination σ1 of the first magnetic field region deviates from 0° intentionally and not accidentally due to an inaccuracy in the alignment. The accuracy with which the exit inclination σ1 of the first magnetic field region can be adjusted is, for example, + / - 0.1° or better, preferably + / - 0.05° or better.

[0028] By adjusting the exit inclination, which deviates from 0°, it is possible to significantly further reduce aberrations of the magnet array. This is surprising in that this geometric requirement is not at all intuitive: In particular, when the magnet array is integrated into a multi-beam particle microscope as a beam splitter, this leads to the situation where an extension of the particle-optical axis A of the objective lens does not orthogonally intersect the exit region of the first magnetic field region of the magnet array. It is therefore surprising that aberrations of the magnet array and also of the multi-beam particle microscope are significantly reduced with such a geometric arrangement.In particular, a reduction in a beam switch-induced image field tilt and a beam switch-induced image field astigmatism is achieved by a factor of approximately 6 each compared to a magnet arrangement in which the exit tilt σ1 of the first magnetic field region is 0° or in a multi-beam particle microscope in which an extension of the particle-optical axis A of the objective lens orthogonally intersects the exit region of the first magnetic field region. For example, an image field tilt δ in an object plane can be reduced to δ ≤ 0.05°, preferably δ ≤ 0.04° - and this without the use or necessity of an additional active corrector such as a multi-stigmator arrangement. In addition, the resolution of a multi-beam particle microscope can also be significantly improved by means of the invention, namely by a factor of approximately 1.5 to 2. All other aberrations of the second order or higher are also small or negligible in total.stay small.

[0029] A deflection of particle beams in essentially different directions can be achieved with magnetic fields that point in essentially opposite directions; the magnetic field strengths in the two magnetic field regions can be essentially identical or different.

[0030] The control parameters of the magnet arrangement are, in particular, the positions (height or z-positions) of the entry and exit points into the various magnetic field regions, as well as the corresponding entry and exit angles or inclinations of the entry and exit regions. By setting these control parameters, the respective arc length in a magnetic field region can be adjusted (for a given magnetic field and a given kinetic energy of the charged particles), along which the charged first single-particle beams move through the magnetic field regions.

[0031] The magnetic field regions themselves can be formed in a manner known per se. They are particularly designed to generate homogeneous magnetic fields, with the direction of the magnetic field oriented orthogonally to the direction of movement of the first individual particle beams. For example, the magnetic field regions can each be formed by two spaced-apart plates made of magnetizable material, each of which has recesses milled into it, into which current conductors or coils are inserted. However, other embodiments are also possible.

[0032] The charged first single-particle beams can be, for example, electrons, positrons, muons, ions, or other charged particles. The charged second single-particle beams can be mirror particles of the first charged single-particle beams, secondary electrons, or backscattered electrons. The particle-optical arrangement is therefore, in principle, flexible in its use.

[0033] The terms primary particle-optical beam path and secondary particle-optical beam path are used as is customary in technical jargon. However, it should be noted at this point that the primary particle-optical beam path, like the secondary particle-optical beam path, describes the paths of the multitude of first and second individual particle beams, respectively. For the purposes of simplification, however, depending on the context, the terms primary particle-optical beam path or secondary particle-optical beam path can of course only refer to an individual particle beam moving along the particle-optical axis of the system, or to the central beam, respectively. The central beam corresponds to the middle (i.e., central) individual particle beam of the bundle of individual particle beams. The direction of the particle-optical axis Z upon entry into one or more of the individual particle beams is...when exiting a magnetic field area is defined by the direction of the central beam, which is preferably identical to the centroid beam of all individual particle beams of the beam.

[0034] According to a preferred embodiment of the invention, the following relationship applies to the exit inclination σ1 of the first magnetic field region: |σ1| ≥ 0.5°, preferably |σ1| ≥ 1°, |σ1| ≥ 3°, or |σ1| ≥ 5°. The exit inclination σ1 is thus a "true" inclination and greater than it would be due solely to inaccuracies in the alignment. The sign or direction of the inclination depends on the specific design of the magnet arrangement and the charge of the primary particle beams used.

[0035] According to a further preferred embodiment of the invention, the following relationship applies to the exit inclination σ of the first magnetic field region: 0° < |σ1| ≤ 10°, preferably 1° ≤ |σ1| ≤ 9°, or most preferably 3° ≤ |σ1| ≤ 7°. Limiting the exit inclination σ to a maximum value can be useful if the geometric conditions of the second particle-optical beam path must also be taken into account. It is possible that a limited exit inclination σ1 contributes to limiting the absorption of aberrations of the secondary particle-optical beam path as it travels through the first magnetic field region. However, this depends on the specific design of a secondary path.

[0036] According to a further preferred embodiment of the invention, the following relationship applies to the entry inclination φ1 of the first magnetic field region: |φ1| > 0, in particular |φ1| ≥ 5° or |φ1| ≥ 10°. The direction of the exit inclination σ1 can be opposite to the entry inclination φ1. However, other implementations are also possible.

[0037] According to a preferred embodiment of the invention, the following relation applies to an entry inclination φ2 of the second magnetic field region: |φ2| ≤ 10°, preferably |φ2| ≤ 5°. Additionally or alternatively, the following applies to an exit inclination σ2 of the second magnetic field region: |σ2| ≤ 10°, preferably |σ2| ≤ 5°. This limitation of the inclination angles contributes to fewer aberrations occurring in the primary particle-optical beam path when entering and exiting the second magnetic field region. The direction of the entry inclination φ2 and the direction of the exit inclination σ2 can be different or opposite in sign. However, it is also conceivable for the entry inclination φ2 and the exit inclination σ2 to have the same sign.

[0038] According to a preferred embodiment of the invention, the particle-optical arrangement further comprises a deflector arrangement which is arranged in front of the second magnetic field region in the direction of the primary particle-optical beam path and which is configured to adjust the entry direction of the primary particle-optical beam path into the second magnetic field region and thus the required entry inclination φ2 with an accuracy of + / -0.1° or better, in particular of + / -0.05° or better or of + / -0.025° or better, and which is configured to adjust the entry location of the primary particle-optical beam path into the first magnetic field region with an accuracy of + / -0.3 mm or better, in particular of + / -0.1 mm or better or even + / -0.05 mm or better.The deflector arrangement preferably comprises two adjustment deflectors that can be precisely and independently adjusted, allowing both the offset and the tilt of the first individual particle beams upon entering the magnet arrangement to be precisely and independently adjusted. This prevents any recurrence of beam switch aberrations that were already corrected by the design of the magnet arrangement, such as field tilt, field astigmatism, global astigmatism, or other second- and third-order aberrations, in the case of tilted or offset beam coupling. The adjustment deflectors can, for example, each be configured as electrostatic deflectors and / or magnetic deflectors.

[0039] According to a preferred embodiment of the invention, during operation of the particle-optical arrangement, the direction of the magnetic fields in all magnetic field regions of the magnet arrangement is essentially orthogonal to the optical axis of the primary particle-optical beam path, and the magnetic fields are essentially homogeneous. The paths described by the first individual particle beams in the magnet arrangement (circular paths or helical paths with path radius r) B ) can be adjusted better and more precisely. For a path radius r B For example, the following applies: 0.1m ≤ r B ≤ 10.0m.

[0040] According to a preferred embodiment of the invention, the following relationship applies to a sum SUM = (S1 / R1) + (S2 / R2): 0.60 ≤ SUM ≤ 0.80, preferably 0.65 ≤ SUM ≤ 0.75. Here, R1 denotes the radius and S1 the arc length of the primary particle-optical beam path in the first magnetic field region. Correspondingly, R2 denotes the radius and S2 the arc length of the primary particle-optical beam path in the second magnetic field region. The above-given condition for the sum of the ratios of arc length to radius of the magnetic field regions can be used to influence the strength of the focusing effect of the magnet arrangement in the first particle-optical beam path. Upon entering or exiting each magnetic field region, the charged first individual particle beams each experience a focusing, albeit weak, due to the quadrupole fields that occur. This focusing must not be too great.Limiting the focusing allows for easier installation of the magnet array or particle-optical array into a multi-beam particle microscope.

[0041] Existing dimensions of an existing multi-beam particle microscope need to be modified less, which simplifies the overall design.

[0042] According to a further preferred embodiment of the invention, the following relationship applies to the path of the primary particle-optical beam path in the first magnetic field region and in the second magnetic field region for a ratio V = (S2 / R2) / (S1 / R1) during operation of the particle-optical arrangement: 0.7 ≤ V ≤ 0.9, in particular 0.75 ≤ V ≤ 0.85. Here, R1 again denotes the radius and S1 the arc length of the primary particle-optical beam path in the first magnetic field region. Analogously, R2 denotes the radius and S2 the arc length of the primary particle-optical beam path in the second magnetic field region. In principle, a weaker and thus longer magnetic field region with a correspondingly longer arc length exerts smaller aberrations on the primary particle-optical beam path than a shorter and stronger magnetic field region that causes the same deflection effect or the same deflection by the same angle.However, if only long and weak magnetic field regions are placed in the magnet arrangement, this increases the overall height of the magnet arrangement. If the height of the magnet arrangement is to be kept as constant as possible, particularly with a view to using the magnet arrangement in a multi-beam particle microscope, certain value ranges for the ratio V are advantageous. A value of V < 1 essentially means that it is advantageous to control the first magnetic field region with a relatively short arc length and also with a relatively strong, homogeneous magnetic field during operation. In contrast, the second magnetic field region can be controlled with a weaker magnetic field during operation, and the second magnetic field region can also be longer, resulting in a larger arc length S2.

[0043] According to a preferred embodiment of the invention, a first drift region, which is essentially free of magnetic fields, is arranged in the primary particle-optical beam path between the first magnetic field region and the second magnetic field region. Providing a drift region between the first magnetic field region and the second magnetic field region offers advantages in the design of the particle-optical arrangement, particularly with a predetermined entry point and a predetermined exit point from the particle-optical arrangement: This provides more independent control parameters for the magnet arrangement, which offers more options for correcting imaging errors. Furthermore, a greater distance between the magnetic field regions contributes to reducing or avoiding interaction effects between the magnetic field regions.In addition, spatial separation between the primary particle beams and the secondary particle beams can be facilitated.

[0044] According to a preferred embodiment of the invention, the drift region has a length LD, for which LD ≥ 8 cm, preferably LD ≥ 10 cm, applies. With this length LD, it is also quite possible to arrange one or more magnetic field regions (only) of the second particle-optical beam path at least partially in a gap between the first magnetic field region and the second magnetic field region, or to allow them to extend slightly into the gap.

[0045] According to a further preferred embodiment of the invention, a total height of the magnet arrangement, which is defined by a distance between the entry point of the primary particle-optical beam path into the second magnetic field region and the exit point of the primary particle-optical beam path from the first magnetic field region, is less than or equal to 35 cm, preferably less than or equal to 30 cm and most preferably less than or equal to 25 cm.

[0046] According to a further preferred embodiment of the invention, the magnet arrangement in the primary particle-optical beam path does not have any further magnetic field regions that are designed to deflect the primary particle-optical beam path by more than 2°, preferably by more than 1°, and most preferably by more than 0.5°. In other words, according to this preferred embodiment, ideally exactly two magnetic field regions are provided in the primary particle-optical beam path. Limiting the number of magnetic field regions in the primary particle-optical beam path offers the advantage that the multitude of first individual particle beams are not focused too strongly overall when moving through the magnet arrangement. When entering or exiting each magnetic field region, the charged first individual particle beams each experience a focusing, albeit weak, due to the quadrupole fields that occur.Limiting the magnetic field areas to a relatively small number also limits this essentially unwanted focusing.

[0047] According to a preferred embodiment of the invention, the first magnetic field region has two parallel plates with a plate spacing D1, between which a homogeneous magnetic field is generated during operation of the particle-optical arrangement. The entrance region of the first magnetic field region is linear and has a width BE1, wherein the following relationship applies to a ratio VPE1 = BE1 / D1: VPE1 ≥ 2.5, preferably VPE1 ≥ 3.0 or most preferably VPE1 ≥ 3.5. Additionally or alternatively, the exit region of the first magnetic field region is linear and has a width BA1, wherein the following relationship applies to a ratio VPA1 = BA1 / D1: VPA1 ≥ 2.5, preferably VPA1 ≥ 3.0 or most preferably VPA1 ≥ 3.5. The above ratios VPE1 and VPA1 contribute to a further reduction of aberrations. This applies in particular to the image field tilt and the image field astigmatism.The linear entry / exit region for the particle-optical beam path is located between the two plates and is often referred to as a trench. Therefore, it would be advantageous to make the trenches as wide as possible. However, this is only structurally possible or sensible to a limited extent if additional magnetic field regions of the second particle-optical beam path are to be arranged. These could collide with the magnetic field regions of the first particle-optical beam path. Another option for achieving the above ratio is to choose the smallest possible distance between the two plates, for example, D1 ≤ 20 mm or D1 ≤ 15 mm.

[0048] According to a preferred embodiment of the invention, the second magnetic field region has two parallel plates with a plate spacing D2, between which a homogeneous magnetic field is generated during operation of the particle-optical arrangement. The entrance region of the second magnetic field region is linear and has a width BE2, wherein the following relationship applies to a ratio VPE2 = BE2 / D2: VPE2 ≥ 2.5, in particular VPE2 ≥ 3.0 or VPE2 ≥ 3.5. Additionally or alternatively, the exit region of the second magnetic field region is linear and has a width BA2, wherein the following relationship applies to a ratio VPA2 = BA2 / D2: VPA2 ≥ 2.5, preferably VPA2 ≥ 3.0, most preferably VPA2 ≥ 3.5. The above ratios VPE1 and VPA1 contribute to a further reduction of aberrations. This applies in particular to the image field tilt and the image field astigmatism.The linear entry / exit region for the particle-optical beam path is located between the two plates and is often referred to as a trench. Therefore, it would be advantageous to make the trenches as wide as possible. However, this is only structurally possible or sensible to a limited extent if additional magnetic field regions of the second particle-optical beam path are to be arranged. These could collide with the magnetic field regions of the first particle-optical beam path. Another option for achieving the above ratio is to choose the smallest possible distance between the two plates, for example, D2 ≤ 20 mm or D2 ≤ 15 mm.

[0049] According to a preferred embodiment of the invention, the magnet arrangement comprises a beam tube arrangement within which at least the first particle-optical beam path runs within the magnet arrangement. During operation of the particle-optical arrangement, the following relationship applies to a fill factor F of the beam tube arrangement: F ≤ 55%, preferably F ≤ 35% or most preferably F ≤ 10%. The fill factor is given as the ratio of the maximum radius r of a beam bundle (the totality of the primary individual particle beams or the mFOV) to the inner diameter Ri of the beam tube or beam tube arrangement. The beam tube comprises a non-magnetic material. For a given maximum radius r of the beam bundle, the inner radius Ri of the beam tube can be dimensioned accordingly.This minimizes contamination of the beam tube due to interaction with the charged particle beams during operation, preventing unwanted beam deflections caused by charged contamination spots on the inside of the beam tube. The fill factor should be considered when selecting the plate spacings D1 and D2 of the magnetic field areas.

[0050] According to a preferred embodiment of the invention, the following applies to a splitting angle γ by which the primary particle-optical beam path is deflected in the first magnetic field region during operation of the particle-optical arrangement: γ ≥ 14°, preferably γ ≥ 16° and most preferably γ ≥ 18°. The splitting angle is a measure of the maximum possible separation of the primary particle-optical beam path from the secondary particle-optical beam path. The splitting angle γ must not be chosen too small, otherwise additional magnetic field regions for the secondary particle-optical beam path cannot be easily integrated into the magnet arrangement of the particle-optical arrangement. For example, it could happen that additional magnetic field regions that are exclusively assigned to the secondary particle-optical beam path collide with the magnetic field regions of the primary particle-optical beam path.For example, crosstalk can occur between different magnetic field areas.

[0051] According to a preferred embodiment of the invention, the entrance inclination of the first magnetic field region is selected such that an exit angle η of the secondary particle-optical beam path from this first magnetic field region is limited to η ≤ 35°, preferably η ≤ 25°, or most preferably η ≤ 15°. This prevents the accumulation of large aberrations upon exiting the first magnetic field region and additionally creates space for any additional secondary path magnetic field regions in the gap between the first magnetic field region and the second magnetic field region. Further details will be provided below.

[0052] According to a preferred embodiment of the invention, the magnet arrangement in the secondary particle-optical beam path has at least one further magnetic field region after passing through the first magnetic field region.

[0053] According to a preferred embodiment of the invention, the magnet arrangement in the secondary particle-optical beam path, after passing through the first magnetic field region, has at least two further magnetic field regions configured to precisely couple the particle-optical axis in the secondary beam path with respect to offset and angle into a downstream projection optics system, in response to varying energies of secondary particles whose path forms the second particle-optical beam path. The varying energy of the secondary particles can result, for example, from a changed setting of a landing energy.

[0054] According to a preferred embodiment of the invention, the magnet arrangement in the secondary particle-optical beam path, after passing through the first magnetic field region, has at least six further magnetic field regions and / or quadrupole fields, which are configured to precisely couple the particle-optical axis in the secondary beam path with respect to offset and angle into a subsequent projection optics when the energy of secondary particles, whose path forms the second particle-optical beam path, varies and additionally to enable paraxially stigmatic, paraxially distortion-free and paraxially dispersion-free imaging.

[0055] 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 magnetic field region and the second magnetic field region of the primary particle-optical beam path.

[0056] According to a further preferred embodiment of the 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. However, it can also be arranged substantially continuously between all magnetic field regions of the primary particle-optical beam path and all magnetic field regions of the secondary particle-optical beam path. For example, the magnetic shielding wall comprises a web made of soft magnetic material, which minimizes crosstalk between the primary and secondary path magnetic field regions.

[0057] According to a further preferred embodiment of the invention, the particle-optical arrangement is a multi-beam particle microscope and the particle-optical arrangement further comprises the following: a multi-beam particle generator configured to generate a first field of a plurality of charged first single particle beams; a first particle optics with a primary particle optical beam path, which is configured to image the generated first individual particle beams onto an object plane, so that the first individual particle beams strike an object at impact locations that form a second field; a detection unit with a plurality of detection regions forming a third field; a second particle optics with a secondary particle-optical beam path configured to image second single-particle beams emanating from the impact locations in the second field onto the third field of detection regions of the detection system; a magnetic and / or electrostatic objective lens through which both the first and the second single-particle beams pass; and a controller configured to control particle-optical components in the primary and / or secondary particle-optical beam path and / or components of the magnet arrangement, wherein the magnet arrangement is arranged in the first particle-optical beam path between the multi-beam particle generator and the objective lens, and wherein the magnet arrangement is arranged in the second particle-optical beam path between the objective lens and the detection unit.

[0058] The charged first single-particle beams can be, for example, electrons, positrons, muons, ions, or other charged particles. It is advantageous if the number of first single-particle beams is 3n (n-1) + 1, where n is any natural number. The first single-particle beams can then be arranged in a hexagonal field. However, other arrangements of the first single-particle beams are also possible. The second single-particle beams can be backscattered electrons or secondary electrons. For analysis purposes, it is preferable for the low-energy secondary electrons to be used for image generation. However, it is also possible to use mirror ions / mirror electrons as second single-particle beams, i.e., first single-particle beams that reverse directly in front of the object or at the object.

[0059] The magnet arrangement of the multi-beam particle microscope can, of course, be further 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, it is possible to arrange one or two or three additional magnetic field regions in the secondary particle-optical beam path, as already described in the prior art in EP 1 668 662 B1. This allows imaging errors in the secondary particle-optical beam path to be corrected by the magnet arrangement or the beam switch.

[0060] According to a preferred embodiment of the invention, the particle-optical axis A of the objective lens coincides with the direction of the particle-optical axis Z of the primary particle-optical beam path upon exiting the first magnetic field region. The exit region of the first particle-optical beam path from the first magnetic field region is not orthogonal to the particle-optical axis A of the objective lens. In this embodiment of the invention, the exit inclination σ1 of the first magnetic field region, which deviates from 0°, thus has a real, visible consequence. Illustratively speaking, the exit region of the first particle-optical beam path from the first magnetic field region is tilted relative to the orthogonal to the particle-optical axis A of the objective lens.The fact that particle-optical images with significantly reduced aberrations can be achieved with this geometric arrangement is surprising and has been demonstrated in simulations, albeit very clearly and significantly. The objective lens can comprise an objective lens system that includes magnetic and / or electrostatic lenses.

[0061] According to a preferred embodiment of the invention, the following relationship applies to the distance OLBS between the objective lens and the exit region of the first magnetic field region: OLBS ≤ 75 mm, preferably OLBS ≤ 70 mm. The distance between the magnet arrangement and the objective lens is thus relatively small. This contributes to reducing the overall height of the multi-beam particle microscope. This is particularly important in laboratory environments where ceiling or room height is typically limited.

[0062] According to a preferred embodiment of the invention, the imaging of the plurality of first individual particle beams into the object plane is essentially distortion-free, and / or the imaging of the first single particle beams into the object plane is essentially dispersion-free; and / or The impact points of the first individual particle beams in the object plane are astigmatic and round. Additionally or alternatively, it is also possible to correct other aberrations in particle-optical imaging. Depending on the design, the magnet arrangement according to the invention offers appropriate adjustment parameters for correction purposes. The correction can also include a correction for a tilt of the sample and / or a correction for a focus tilt due to a misalignment of an illumination system / condenser lens system.

[0063] According to a preferred embodiment of the invention, the imaging of the first individual particle beams into the object plane has substantially no image field inclination.

[0064] According to a preferred embodiment of the invention, the imaging of the first single particle beams into the object plane is substantially free of image field astigmatism.

[0065] According to a preferred embodiment of the invention, all other second and third order aberrations in the object plane amount to a maximum of only 1 nm, in particular a maximum of only 0.5 nm or a maximum of only 0.25 nm. The specified values ​​are scaled by means of the numerical aperture NA used and the image field size in the object plane and are determined at a landing energy of 1.5 keV.

[0066] It is possible to combine the embodiments described above in whole or in part, provided that this does not result in any technical contradictions.

[0067] The invention will be better understood with reference to the accompanying figures, in which: Fig. 1: shows schematically a multi-beam particle microscope; Fig. 2: shows schematically a multi-beam particle microscope with a beam switch or a magnet arrangement according to the prior art; Fig. 3: shows schematically a magnet arrangement according to the prior art and the occurrence of an image field tilt; Fig. 4: shows schematically control parameters for a magnet arrangement with two magnetic field regions in the primary path according to the prior art; Fig. 5: shows schematically control parameters for a magnet arrangement with two magnetic field regions in the primary path; Fig. 6: schematically shows inclinations of an entry region and an exit region of the first magnetic field region in the primary path; Fig. 7: schematically shows inclinations of an entry region and an exit region of the second magnetic field region in the primary path; Fig. 8: shows schematically a deflector arrangement in front of the second magnetic field region in the primary path; and Fig. 9: shows schematic geometric conditions of the first magnetic field region; Fig. 10: shows schematic geometric conditions of the second magnetic field region; Fig. 11: schematically illustrates a fill factor of the jet pipe arrangement; Fig. 12: shows schematically a shielding wall between magnetic field regions of the primary path and the secondary path; and Fig. 13: shows schematically an arrangement or alignment of the first magnetic field region in the particle optical beam path with respect to the secondary path.

[0068] Fig. Figure 1 schematically shows a multi-beam particle microscope 1. The multi-beam particle microscope 1 has a beam generation device 300 with a particle source 301, for example, an electron source. A diverging particle beam 309 is collimated by a sequence of condenser lenses 303.1 and 303.2 and impinges on a multi-aperture arrangement 305. The multi-aperture arrangement 305 comprises several multi-aperture plates 306 and a field lens 308. The multi-aperture arrangement generates a plurality of individual particle beams 3 or individual electron beams 3. Center points of apertures of the multi-aperture plate arrangement are arranged in a field, which is imaged onto another field formed by beam spots 5 in the object plane 101. The distance between centers of apertures of a multi-aperture plate 306 can be, for example, 5 µm, 100 µm and 200 µm.The diameters D of the apertures are smaller than the distance between the centers of the apertures; examples of diameters are 0.2 times, 0.4 times, and 0.8 times the distance between the centers of the apertures.

[0069] The multi-aperture arrangement 305 and the field lens 307 are configured to generate a plurality of focal points 323 of primary beams 3 in a grid arrangement within a surface 325. The surface 325 does not have to be a flat surface, but can be a spherically curved surface to accommodate field curvature of the subsequent particle-optical system.

[0070] The multi-beam particle microscope 1 further comprises a system of electromagnetic lenses 103 and an objective lens 102, which image the beam foci 323 from the intermediate image area 325 into the object plane 101 in a reduced size. The first individual particle beams 3 pass through the beam switch 400 and a collective beam deflection system 500, with which the plurality of first individual particle beams 3 are deflected during operation and the image field is scanned. The first individual particle beams 3 impinging on the object plane 101 form, for example, a substantially regular field, wherein distances between adjacent impingement points 5 can be, for example, 1 µm, 10 µm, or 40 µm. The field formed by the impingement points 5 can, for example, have a rectangular or hexagonal symmetry.

[0071] The object 7 to be examined can be of any type, for example, a semiconductor wafer or a biological sample, and it can comprise an array of miniaturized elements or the like. The surface 15 of the object 7 is arranged in the object plane 101 of the objective lens 102. The objective lens 102 can comprise one or more electron-optical lenses. It can be, for example, a magnetic objective lens and / or an electrostatic objective lens.

[0072] The primary particles 3 striking the object 7 generate interaction products such as secondary electrons, backscattered electrons, or primary particles that have undergone a reversal of motion for other reasons, which emanate from the surface of the object 7 or from the first plane 101 or object plane 101. The interaction products emanating from the surface 15 of the object 7 are formed into secondary particle beams 9 by the objective lens 102. The secondary beams 9 pass through the beam switch 400 after the objective lens 102 and are fed to a projection system 200. The projection system 200 has an imaging system 205 with first and second lenses 210 and 220, a contrast aperture 222, and a multi-particle detector 209. The points of incidence of the second single-particle beams 9 on detection areas of the multi-particle detector 209 are located in a third field at a regular distance from one another.Example values ​​are 10 µm, 100 µm and 200 µm.

[0073] The multi-beam particle microscope 1 further comprises a computer system or a control unit 10, which in turn can be designed as a single part or in multiple parts, and which is designed both to control the individual particle-optical components of the multi-beam particle microscope 1 and to evaluate and analyze the signals obtained with the multi-detector 209 or the detection unit 209.

[0074] Further information on such multi-beam particle beam systems or multi-beam particle microscopes 1 and components used therein, such as particle sources, multi-aperture plates and lenses, can be obtained from the international patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596 A1, WO 2011 / 124352 A1 and WO 2007 / 060017 A2 and the German patent applications DE 10 2013 016 113 A1 and DE 10 2013 014 976 A1.

[0075] The beam switch 400 or the magnet arrangement 400 is in Fig. 1 is shown only schematically without further details. In principle, it is possible that the magnet arrangement 400 is the magnet arrangement 400 that is included in the particle-optical arrangement according to the invention. However, the beam switch 400 known from the prior art or from EP 1 668 662 B1 is also compatible with the multi-beam particle microscope 1 according to Fig. 1 compatible.

[0076] Fig. Figure 2 shows a schematic sectional view of a multi-beam particle microscope 1 with a beam switch 400 or a magnet arrangement 400 according to the prior art. In particular, aspects of the known beam switch 400 are illustrated. Fig. In the multi-beam particle microscope 1 shown in Figure 2, a particle source 301 emits a particle beam that passes through a magneto-optical condenser lens system 303 and then impinges on the multi-aperture arrangement 305. This serves as a multi-beam particle generator, and individual particle beams 3 emanating from the multi-aperture arrangement 305 then pass through a magneto-optical field lens system 307 and then enter the magneto-optical beam splitter 400 or magnet arrangement 400. The beam splitter 400 shown comprises a beam tube arrangement 490, which in the example shown is Y-shaped and comprises three legs 461, 462, and 463. In addition to two flat, interconnected structures for holding the magnetic sectors or magnetic field regions 410, 430, the beam switch 400 has the two magnetic sectors or magnetic field regions 410 and 430 contained therein or fixed thereto.After passing through the beam switch 400, the first particle beams 3 pass through a scan deflector 500 and then the particle-optical objective lens 102 before the primary particle beams 3 impinge on the surface 15 of an object 7, in this case a semiconductor wafer with HV structures. HV structures refer to the predominantly horizontal or vertical orientation of semiconductor structures. The semiconductor wafer 7 is positioned by a traversing stage 600 below the objective lens 102. The impingement of the first individual particle beams 3 releases secondary particles or second individual particle beams 9 from the object 7. After exiting the object 7, the second individual particle beams 9 first pass through the particle-optical objective lens 102, then the scan deflector 500, and then the beam switch 400.The second single-particle beams 9 exit the beam splitter 400 through the leg 462, pass through a projection lens system 205 (shown in a highly simplified manner), pass through an electrostatic element 260, the so-called antiscan, and then impinge on a particle-optical detection unit 209. The computer system 10 or the control unit 10, which is used to control particle-optical components and other parts of the multi-beam particle microscope 1 according to . Fig. 2 is in Fig. 2 not shown for reasons of simplicity.

[0077] Fig. 3 schematically shows a magnet arrangement according to the prior art and the occurrence of an image field tilt. In the example shown, the magnet arrangement 400 comprises a first magnetic field region 410 and a second magnetic field region 430, whose magnetic fields are oriented opposite to one another and through which a primary particle-optical beam path 13 passes. Furthermore, in the example shown, three further magnetic field regions 450, 460, and 470 are provided. The secondary particle-optical beam path 11 runs through the first magnetic field region 410 as well as through these additional magnetic field regions 450, 460, and 470. The magnetic field in the magnetic field region 450 is oriented in the same direction as the magnetic field in the magnetic field region 410, so that the curvature of the second particle-optical beam path 11 in these magnetic field regions 410, 450 is free of curvature changes.

[0078] At the Fig. In the beam splitter shown in Figure 3, a tilt angle β exists between the optical axis of the first particle-optical beam path 13 and the axis A, which corresponds to the particle-optical axis of the objective lens 102 or its continuation. A right angle is set between a lower edge of the first magnetic field region 410 and the axis A, which is considered favorable for the overall imaging properties into the object plane 101 according to the prior art.

[0079] The angle γ is the so-called splitting angle, which provides a measure of the separation of the primary particle-optical beam path 13 from the second particle-optical beam path 11 within the magnetic field region 410. This angle must not be chosen too small, otherwise there may not be sufficient space available for the arrangement of magnetic field regions 450, 460, and 470 (and possibly other elements of the magnet arrangement 400) in the secondary particle-optical beam path 11.

[0080] Image aberrations of the first particle-optical beam path 13 can be largely corrected, and the image can be essentially stigmatic in the first order and essentially distortion-free in the first order. However, in the context of increasingly precise measurement tasks for multi-beam particle microscopes 1, ever higher demands are placed on the resolution, and it has been found that Fig. 3, the field tilt d often accounts for a large part of the remaining residual error. This field tilt ɗ is in Fig. 3 not drawn to scale. First individual particle beams 3 strike the object or object plane 101 at slightly different heights, with the location of the minimum particle beam diameter being regarded as the focal point. The individual particle beam 3, which lies exactly on the particle-optical axis A, has exactly one focal position on the object plane 101, the first individual particle beam 3 arranged to the left of it has a focal position just in front of the object plane 101, and the first individual particle beam 3 arranged to the right of the particle-optical axis A has a focal position slightly below the object plane 101. The creation of the image field inclination d is essentially explained by slightly different path lengths traveled by the plurality of first individual particle beams 3 within the magnet arrangement 400.Until now, it was not possible in the prior art to compensate for the image field inclination d in the design of the magnet arrangement 400 with only two magnetic field regions 410, 430 in the primary path.

[0081] Fig. Fig. 4 shows schematically the control parameters of a magnet arrangement 400 according to the prior art with two magnetic field regions 410 and 430 in the primary path 13; the secondary path is in Fig. 4 is not shown. In order to achieve a perpendicular exit of the primary particle-optical beam path 13 from the first magnetic field region 410 and good imaging properties at the objective lens (not shown), the exit point P1 and the inclination of the exit region G1 are fixed in a design of the magnetic field arrangement 400, the angle α1 is 90°, and the position in the direction of the Z axis is defined as z1. The remaining entry and exit regions in the magnetic field regions 410, 430 are therefore available for adapting particle-optical properties. The points P2, P3, and P4 can, for example, be described by their z-positions z2, z3, z4 and by the angles α2, α3, and α4; however, other coordinates can of course also be selected for this purpose. By selecting or defining the points P2, P3 and P4 accordingly, the respective arc lengths S2 and S1 in the magnetic field areas 430 and 410 are in principle adjusted.A drift section 405 is arranged between the points P2 and P3, the length of which is determined by the definition of the points P2 and P3.

[0082] The Fig. The system shown in Figure 4 has a maximum of six independent control parameters for a fixed point P1, fixed inclination G1, and fixed magnetic field strength in the magnetic field regions 410 and 430: the z-positions z2, z3, and z4, as well as the angles α2, α3, and α4. These six control parameters can be used to optimize the imaging properties of the magnet arrangement 400 and reduce aberrations. A complete compensation of path differences and thus a substantial elimination of an image field inclination in addition to already corrected aberrations is possible with the system shown in Fig. However, the arrangement shown in Figure 4 is only possible, if at all, for certain irradiation conditions.

[0083] Fig. 5 schematically shows a magnet arrangement 400 with two magnetic field regions 410, 430 in the primary path 13. The geometric arrangement of the magnet arrangement 400 according to Fig. 5 differs in one important aspect from the Fig. 4: The angle α1 between the exit region G1 and the particle-optical axis A is not 90°. Instead, the exit region G1 is inclined or tilted relative to the orthogonal to the direction of the particle-optical beam path 13 at the exit point P1. This exit inclination σ1 of the first magnetic field region 410 relative to the orthogonal to the particle-optical axis Z of the primary particle-optical beam path 13 is shown in Fig. 5. Changing the exit inclination σ1 leads to significantly reduced aberrations when designing the magnet arrangement. In particular, an image field inclination δ and also an image field astigmatism can be essentially eliminated. Other second-order and higher-order aberrations can also be kept correspondingly small or are in the range that is also affected by the magnet arrangement 400 according to Fig. 4 is known.

[0084] A possible variation of the exit inclination σ1 provides a further degree of freedom for the design of the magnet arrangement with a fixed position of the exit point P1, and surprisingly, this non-intuitive control parameter σ1 or σ1 is a key to significantly further reducing aberrations. The magnet arrangement 400 or its geometric representation in Fig. 5 is of course not to scale. According to one example, the following relationship applies to the exit inclination σ1 of the first magnetic field region 410: |σ1| ≥ 0.5°, preferably |σ1| ≥ 1°, |σ1| ≥ 3° or most preferably |σ1| ≥ 5°. The exit inclination σ1 of the first magnetic field region 410 therefore deviates significantly from 0° in some cases; in any case, the deviation is greater than an adjustment inaccuracy, which can be, for example, a deviation of + / - 0.1° or + / - 0.05° or better. According to another example, the exit inclination σ1 of the first magnetic field region can satisfy the following relationship: 0° < |σ1| ≤ 10°, preferably 1° ≤ |σ1| ≤ 9° or 3°≤ |σ1| ≤ 7°.

[0085] In Fig. 5, a drift path 405 is arranged between the second magnetic field region 430 and the first magnetic field region 410, in which the charged first single-particle beams 3 move in a straight line, or the primary path 13 runs in a straight line. The length LD of this drift path 405 can, for example, be LD ≥ 8 cm, preferably LD ≥ 10 cm.

[0086] It has further proven advantageous if the total length of the magnet arrangement 400, which is defined by a distance between the entry point P4 of the primary particle-optical beam path 13 into the second magnetic field region 430 and the exit point P1 of the primary particle-optical beam path 13 from the first magnetic field region 410, is less than or equal to 35 cm, preferably less than or equal to 30 cm, and most preferably less than or equal to 25 cm. This facilitates the installation of the magnet arrangement in particle-optical systems or in multi-beam particle microscopes, which are often installed in laboratories with limited ceiling heights.

[0087] Fig. Figure 6 schematically shows inclinations of an entry region G2 and an exit region G1 of the first magnetic field region 410 in the primary path. In Fig. 6 shows that not only the exit region G1 has an exit inclination σ1, but also the entrance region G2 is inclined relative to an orthogonal to the particle-optical beam path at the entry point P2 into the first magnetic field region 410, namely by the angle φ1. For example, the following relation can apply to an entrance inclination φ1 of the first magnetic field region 410: |φ1| > 0, preferably |φ1| ≥ 5° or |φ1| ≥ 10°. In the example shown, the directions of the inclinations φ1 and σ1 are opposite. However, it is theoretically also possible for the inclination directions to have the same sign or the same direction of rotation. Fig. 6, the particle-optical axis A is also shown as an imaginary extension of the particle-optical axis of the objective lens 102 of a multi-beam particle microscope 1. However, it should be noted that the definition of the inclinations σ1 and φ1 is independent of this particle-optical axis A, but that for the definition of the inclinations σ1 and φ1, reference is made solely to the direction of the particle-optical beam path Z and to the entrance and exit regions G2, G1. The orthogonals 411, 412 to the particle-optical axis Z are shown in Fig. 6 also shown as dashed auxiliary lines.

[0088] Fig. Figure 7 schematically shows inclinations of an entrance region G4 and an exit region G3 of the second magnetic field region 430 in the primary path 13. The entrance inclination φ2 of the second magnetic field region 430 is again defined as the angle by which the orientation of the entrance region G4 deviates from the orthogonal line 432 to the particle-optical axis Z of the primary particle-optical beam path 13 at the entrance location P4. Completely analogously, the exit inclination σ2 is defined as the angle by which the orientation of the exit region B3 deviates from the orthogonal line 431 to the particle-optical axis Z of the primary particle-optical beam path 13 at point P3. According to one embodiment, the following relation applies to the entrance inclination φ2 of the second magnetic field region 430: |φ2| ≤ 10°, preferably |φ2| ≤ 5°. Additionally or alternatively, the following relation may apply to an exit inclination σ2 of the second magnetic field region 430: |σ2| ≤ 10°, preferably |σ2| ≤ 5°.The smaller the inclinations |φ2| and |σ2| are, the fewer aberrations the charged particles or single particle beams 3 absorb when entering or exiting the magnetic field region 430.

[0089] It has been shown that to significantly reduce second-order aberrations such as field tilt and field astigmatism, the entrance inclination φ2 should be set very precisely. Deviations from the predetermined angle φ2 have a relatively strong impact on aberrations that would otherwise recur and would otherwise be eliminated. Therefore, according to a further embodiment, the particle-optical arrangement comprises a deflector arrangement 475 arranged in front of the second magnetic field region 430 in the direction of the primary particle-optical beam path 13. In the example shown, the deflector arrangement 475 is designed as a double deflector with the deflectors 471 and 472. These can be electrostatic and / or magnetic deflectors.The deflector arrangement 475 is configured to adjust the entry direction of the primary particle-optical beam path 13 into the second magnetic field region 430 and thus the entry inclination φ2 with an accuracy of + / - 0.1° or better, preferably + / - 0.05° or better, or even + / - 0.025° or better. Furthermore, the deflector arrangement 475 is configured to adjust the entry location P4 or P4' of the primary particle-optical beam path 13, 13' into the second magnetic field region 430 with an accuracy of + / - 0.3 mm or better, in particular + / - 0.1 mm or better, or even + / - 0.05 mm or better. The various adjustment options are shown in . Fig. 8 are only shown schematically and greatly exaggerated by the dashed particle-optical beam path 13' and serve only for illustration purposes.

[0090] In general, the deflector arrangement can be used to precisely and independently adjust, for example, two adjustment deflectors 471, 472, so that both the offset and the tilt of the first individual particle beams 3 upon entering the magnet arrangement 400 can be precisely and independently adjusted. This prevents any recurrence of beam switch aberrations that have already been corrected by the design of the magnet arrangement 400, such as field tilt, field astigmatism, global astigmatism, or other second- and third-order aberrations, in the case of tilted or offset beam coupling.

[0091] In addition to the above-described control parameters of the entry locations P1 to P4 and the entry and exit inclinations σ1, φ1, σ2 and φ2, there are fundamentally further control parameters for the design of the magnet arrangement 400. These can be dependent on or independent of the above-mentioned control parameters. According to one embodiment, during operation of the particle-optical arrangement, the directions of the magnetic fields in the first and second magnetic field regions 410, 430 of the magnet arrangement 400 are essentially orthogonal to the particle-optical axis Z of the primary particle-optical beam path 13, and the magnetic fields are essentially homogeneous. In the Fig. In the embodiments illustrated in Figures 3 to 8, the magnetic fields in the magnetic field regions 410 and 430 are oriented opposite to each other. The magnetic field strength can now also be varied (as a dependent control parameter). The magnetic field strength in the first magnetic field region 410 can differ in magnitude from the magnetic field strength in the second magnetic field region 430. Preferably, the magnetic field strength in the first magnetic field region 410 is greater than in the second magnetic field region 430. An associated arc length S1 in the first magnetic field region 410 is preferably shorter than the arc length S2 in the second magnetic field region 430. According to one embodiment, it can then apply that during operation of the particle-optical arrangement for the path of the primary particle-optical beam path 13 in the first magnetic field region 410 and in the second magnetic field region 430 for a ratio V = (S2 / R2) / (S1 / R1) the following relation applies: 0.7 ≤ V ≤ 0.9, preferably 0.75 ≤ V ≤ 0.85.Here, R1 denotes the radius and S1 the arc length of the primary particle-optical beam path 13 in the first magnetic field region 410 and, correspondingly, R2 denotes the radius and S2 the arc length of the primary particle-optical beam path 13 in the second magnetic field region 430. A ratio V that lies in the above-mentioned range contributes to reducing aberrations even further.

[0092] Furthermore, the following relationship can apply to a sum SUM=(S1 / R1) + (S2 / R2): 0.60 ≤ SUM ≤ 0.80, preferably 0.65 ≤ SUM ≤ 0.75. This can help keep the focusing effect of the magnet arrangement 400 within an acceptable, as small as possible, range.

[0093] Fig. Figure 9 schematically shows further geometric relationships of the first magnetic field region 410, which can further contribute to the reduction of aberrations as independent control parameters: Fig. 9a below, the entry region G1 of the first magnetic field region 410, with the particle-optical axis Z pointing into the plane of the paper in the example shown. The first magnetic field region 410 has two parallel plates 481, 482, which in the example shown are spaced apart by a distance D1. The spaced-apart plates 481, 482 can be made of magnetizable material, and recesses can be milled into the plates 481, 482, into which current conductors or coils are inserted. However, other embodiments for the two parallel plates 481, 482 are also possible. The exit region G1 of the first magnetic field region 410 is linear and has a width BA1. As a result, in principle, the entire exit region G1 or trench is linear, and the width BA1 can be defined at all.It has now been found that a ratio of trench width BA1 to plate spacing D1 is advantageous if the following relationship for the ratio VPA1 = WA1 / D1 is fulfilled: VPA1 ≥ 2.5, preferably VPA1 ≥ 3.0 or VPA1 ≥ 3.5. Aberrations can then be reduced even further. The same applies to the ratio VPE1 = BE1 / D1, where BE1 denotes the width of the entrance region of the first magnetic field region 410, which is shown in . Fig. 9b. Here, too, there are advantages in terms of aberration reduction if the following relation applies: VPE1 ≥ 2.5, preferably VPE1 ≥ 3.0 or VPE1 ≥ 3.5.

[0094] In a completely analogous manner, these advantageous geometric conditions also apply to the realization of the second magnetic field region 430. This is shown schematically in Fig. 10. In the illustrated embodiment, the plates 491 and 492 of the second magnetic field region 430 are spaced apart by the distance D2. The width of the entry region is designated BE2, and the width of the exit region is designated BA2. It is advantageous if the following relationship applies to the ratio VPE2 = BE2 / D2: VPE2 ≥ 2.5, preferably VPE2 ≥ 3.0 or VPE2 ≥ 3.5. Accordingly, for a ratio VPA2 = BA2 / D2, the following relationship advantageously applies: VPA2 ≥ 2.5, preferably VPA2 ≥ 3.0 or VPA2 ≥ 3.5.

[0095] In the in the Fig. 9 and Fig. In the exemplary embodiments illustrated in Figure 10, the width of the respective entry region BE1, BE2 may be identical to the width of the respective exit region BA1, BA2. However, these widths may also be different. Furthermore, it is possible for the plate spacing D1 in the first magnetic field region 410 to be identical to the plate spacing D2 of the second magnetic field region 430. However, it is also possible for the plate spacings D1 and D2 to be different from one another. A plate spacing D1 or D2 may, for example, be ≤ 25 mm, ≤ 20 mm, or ≤ 15 mm. However, it must be taken into account how many individual particle beams 3 in total travel through the magnet arrangement 400 during operation of the particle-optical arrangement. The charged individual particle beams 3 must not come too close to the plates 491, 492, 481, 482 in order to avoid imaging errors and / or contamination.

[0096] Fig. 11 illustrates considerations regarding the so-called fill factor of a beam tube 491. According to one embodiment, the magnet arrangement 400 has a beam tube arrangement 490, within which the primary particle-optical beam path 13 runs within the magnet arrangement 400. In Fig. 11 shows a beam bundle mFOV passing through the beam tube 490, which has an outer radius r. In contrast, the beam tube 490 has a maximum inner radius Ri. The fill factor is defined as the ratio of the maximum radius r of the beam bundle mFOV to the inner diameter Ri of the beam tube 490. According to one exemplary embodiment, the following relationship applies to this fill factor F: F ≤ 55%, preferably F ≤ 35% or F ≤ 10%. If the fill factor F is too large, unwanted contamination of the beam tube 490 may occur, or during operation of the particle-optical arrangement, interactions may occur between contamination of the beam tube 490 on the one hand and the charged particle beams 3.9 during operation on the other. This results in unwanted beam deflections due to charged contamination spots on the inside of the 490 beam tube.In this respect, a plate distance D1, D2 cannot be arbitrarily minimized, but it should be ensured that a beam pipe 490 in the particle-optical beam path 13 inside the magnet arrangement 400 also meets these advantageous requirements for the filling factor F.

[0097] Fig. 12 schematically shows a shielding wall 495 between magnetic field regions of the primary path and the secondary path. According to this exemplary embodiment, the magnet arrangement 400 has a magnetic shielding wall 495, which is arranged between at least one of the magnetic field regions 410, 430 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. However, it can of course also be arranged essentially continuously between all magnetic field regions 410, 430 of the primary particle-optical beam path 13 and all magnetic field regions of the secondary particle-optical beam path 11. For example, the magnetic shielding wall 495 comprises a web made of soft magnetic material, which minimizes crosstalk between the primary and secondary path magnetic field regions. In the Fig. In the example shown in Figure 12, at least one magnetic field region 450 of the secondary path 11 extends so far between the first magnetic field region 410 and the second magnetic field region 420 that it intersects the imaginary extension of the particle-optical axis A of an objective lens 102 when the magnet arrangement 400 is integrated as a beam splitter 400 into a multi-beam particle microscope 1. However, this could also be different.

[0098] Fig. 13 schematically illustrates an arrangement or orientation of the first magnetic field region 410 in the particle-optical beam path. The exit inclination of the exit region or groove G1 from the first magnetic field region 410 is different from 0°, as in the previous embodiments. Thus, there is no right angle between the exit region or groove G1 and the particle-optical axis A. The exit direction from the first magnetic field region 410 nevertheless corresponds to the direction of the particle-optical axis A of the objective lens 102 when the particle-optical arrangement is arranged in a multi-beam particle microscope 1. The secondary particle beams 9, e.g., electron beams, which travel through the secondary particle-optical beam path 11 during operation of the particle-optical arrangement, normally have lower kinetic energy than the primary particle beams 3.The secondary particles 9 are therefore slower and are deflected more strongly in the first magnetic field region 410 or have a path radius r. BThe path they describe in the homogeneous magnetic field is smaller than a corresponding path radius of the faster primary particles 3 or electrons. The exit angle η1 of the secondary particle-optical beam path 11 is therefore fundamentally different from the entrance angle φ1 of the primary beams 3 of the primary particle-optical beam path 13. The entrance angle φ and the exit angle η1 can be determined by the entrance inclination of the first magnetic field region 410 or the groove G2. It is advantageous to limit the exit angle η1 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 exiting the first magnetic field region 410 and additional installation space is created for any additional secondary path magnetic field regions in the gap between the first magnetic field region 410 and the second magnetic field region 420. It is also advantageous if the following applies to a splitting angle γ, by which the primary particle-optical beam path 13 is deflected overall in the first magnetic field region 410 during operation of the particle-optical arrangement: γ ≥ 14°, preferably γ ≥ 16° and most preferably γ ≥ 18°.

[0099] According to a further embodiment, at least one of the further magnetic field regions of the secondary particle-optical beam path 11 is arranged in a gap between the first magnetic field region 410 and the second magnetic field region 420 of the primary particle-optical beam path 13.

[0100] For example, the magnet arrangement 400 in the secondary particle-optical beam path 11 can have at least two further magnetic field regions after passing through the first magnetic field region 410, which are designed to project the particle-optical axis Z in the secondary beam path 11 with respect to offset and angle into a subsequent projection optics 200 (see e.g. Fig. 1) precisely. The varying energy of the secondary particles 9 can, for example, result from a change in the landing energy setting.

[0101] According to one embodiment, the magnet arrangement 400 in the secondary particle-optical beam path 11 has, after passing through the first magnetic field region 410, at least six further magnetic field regions and / or quadrupole fields, which are configured to project the particle-optical axis Z in the secondary beam path 11 with respect to offset and angle into a subsequent projection optics 200 (see e.g. Fig. 1) to couple precisely and additionally to enable paraxial stigmatic, paraxial distortion-free and paraxial dispersion-free imaging.

[0102] The magnet arrangements 400 according to the invention, like the magnet arrangements 400 according to the prior art, can be integrated into a multi-beam particle microscope 1, for example in the one shown in Fig. 1 schematically shown.

[0103] According to one exemplary embodiment, an imaging of the plurality of first individual particle beams 3 onto the object plane 101 is essentially free of image field tilt. However, it is of course also possible to correct other imaging errors by appropriately designing the magnet arrangement 400, as has already been described in more detail above. According to one exemplary embodiment, the imaging of the plurality of first individual particle beams 3 into the object plane 101 is essentially distortion-free overall, and / or the imaging of the first individual particle beams 3 into the object plane 101 is essentially dispersion-free; and / or the impact points 5 of the first individual particle beams 3 in the object plane 101 are astigmatic and round. Additionally or alternatively, it is also possible to correct other aberrations during particle-optical imaging. Depending on the design, the magnet arrangement 400 according to the invention offers corresponding adjustment parameters for correction purposes.The correction may also include a correction of a tilt of the sample 7 and / or a correction of a focus tilt due to a misalignment of an illumination system / condenser lens system 303.

[0104] According to one embodiment, the imaging of the first individual particle beams 3 into the object plane 101 is free of field astigmatism. In addition, all other second- and third-order aberrations in the object plane 101 can be a maximum of only 1 nm, preferably a maximum of only 0.5 nm or a maximum of only 0.25 nm. The specified values ​​are scaled using the numerical aperture NA used and the field size in the object plane and are determined at a landing energy of 1.5 keV. List of reference symbols 1 multi-beam particle microscope 3 primary particle beams (single particle beams) 5 beam spots, impact points 7 Object, sample 9 secondary particle beams 10 Computer system, control 11 secondary particle-optical beam path 13 primary particle-optical beam path 15 Sample surface 101 Object level 102 objective lens 105 Axis 200 detector system 205 Projection lens system 209 Detection system, particle multi-detector, detection unit 210 lens 220 lens 222 Contrast aperture 260 Anti-Scan 300 beam generating device 301 particle source 303 collimation lens system 305 multi-aperture arrangement 306 Microoptics 307 Field lens 308 field lens 309 diverging particle beam 323 beam foci 325 intermediate image plane 400 beam switch, magnet arrangement 405 Drift track 410 magnetic field range 411 Orthogonal to the particle-optical axis Z in the exit area (primary path) 412 Orthogonal to the particle-optical axis Z in the entrance area (primary path) 415 Orthogonal to the optical axis in the exit area (secondary path) 430 magnetic field range 431 Orthogonal to the particle-optical axis Z in the exit area 432 Orthogonal to the particle-optical axis Z in the entrance area 450 magnetic field range 460 magnetic field range 461 Leg of the jet pipe assembly 462 Legs of the jet pipe assembly 463 Leg of the jet pipe assembly 466 branching point 470 magnetic field range 475 deflector arrangement 471 first diversion 472 second deflector 481 plate 482 plate 490 jet pipe arrangement 491 plate 492 plate 495 Shielding wall 500 scan deflectors 600 Moving table or positioning device A axis, extension of the particle-optical axis of the objective lens Z particle optical axis D1 Plate spacing D2 plate spacing BE1 Width of the entry area or trench BE2 Width of the entry area or trench BA1 Width of the exit area or trench BA2 Width of the exit area or trench Ri inner radius of jet pipe r Radius of the multi-image field (mFOV) z1... z4 z-positions α1...α4 inclination angle β Tilt angle γ splitting angle δ Angle of field tilt σ1..σ2 Exit inclination, exit angle (primary particle optical beam path) φ1..φ2 entrance inclination, entrance angle (primary particle optical beam path) η1 Exit inclination (secondary particle-optical beam path) G1...G4 Magnetic field area edge, trench, depression P1... P4 point, position S1... S2 Length of a circular arc

Claims

[1] Particle-optical arrangement for providing a primary particle-optical beam path (13) for a plurality of first individual particle beams (3) which, emanating from a multi-beam particle generator, are directed onto an object (7) which can be positioned in an object plane (101) of the arrangement, and a secondary particle-optical beam path (11) for a plurality of second individual particle beams (9) which emanate from the object (7), wherein the particle-optical arrangement has a magnet arrangement (400) which comprises: a first magnetic field region (410) which is traversed by the primary particle-optical beam path (13) and the secondary particle-optical beam path (11) in order to separate the primary particle-optical beam path (13) and the secondary particle-optical beam path (11) from one another; a second magnetic field region (430) which is arranged in the primary particle-optical beam path (13) and which is not arranged in the secondary particle-optical beam path (11), wherein the second magnetic field region (430) is arranged in front of the first magnetic field region (410) with respect to the primary particle-optical beam path (13), and wherein the first magnetic field region (410) and the second magnetic field region (430) deflect the primary particle-optical beam path (13) in different directions; wherein each magnetic field region (410, 430) has an entrance region for the primary particle-optical beam path (13) with an entrance inclination φ and an exit region for the primary particle-optical beam path (13) with an exit inclination σ, wherein the entrance inclination φ is defined as the angle by which the orientation of the entrance region deviates from the orthogonal (412) to the particle-optical axis Z of the primary particle-optical beam path (13), and wherein the exit inclination σ is defined as the angle by which the orientation of the exit region deviates from the orthogonal (411) to the particle-optical axis Z of the primary particle-optical beam path (13), and wherein the exit inclination σ1 of the first magnetic field region (410) deviates from 0°. [2] Particle-optical arrangement according to the preceding claim, wherein the following relation applies to the exit inclination σ1 of the first magnetic field region (410): |σ1| ≥ 0.5°, in particular |σ1| ≥ 1°, |σ1| ≥ 3° or |σ1| ≥ 5° [3] Particle-optical arrangement according to one of the preceding claims, wherein the following relation applies to the exit inclination σ1 of the first magnetic field region (410): 0°<|σ1|≤10°, in particular 1°≤|σ1|≤9° or 3°≤|σ1|≤7° [4] Particle-optical arrangement according to one of the preceding claims, wherein the following relation applies to the entrance inclination φ1 of the first magnetic field region (410): |φ1| > 0, in particular |φ1| ≥ 5° or |φ1 | ≥ 10°. [5] Particle-optical arrangement according to one of the preceding claims, wherein the following relation applies to an entry inclination φ2 of the second magnetic field region (430): |φ2| ≤ 10°, in particular |φ2| ≤ 5°; and / or wherein the following relation applies to an exit inclination σ2 of the second magnetic field region (430): |σ2| ≤ 10°, in particular |σ2| ≤ 5°. [6] Particle-optical arrangement according to one of the preceding claims, which further comprises a deflector arrangement (475) arranged in front of the second magnetic field region (430) in the direction of the primary particle-optical beam path (13), wherein the deflector arrangement (475) is configured to adjust the entry direction of the primary particle-optical beam path (13) into the second magnetic field region (430) and thus the entry inclination φ2 with an accuracy of + / -0.1° or better, in particular of + / -0.05° or better or of + / -0.025° or better, and / or wherein the deflector arrangement (475) is configured to adjust the entry point of the primary particle-optical beam path (13) into the second magnetic field region (430) with an accuracy of + / -0.3 mm or better, in particular of + / -0.1 mm or better or even + / -0.05 mm or better. [7] Particle-optical arrangement according to one of the preceding claims, wherein during operation of the particle-optical arrangement the directions of the magnetic fields in the first (410) and in the second magnetic field region (430) of the magnet arrangement (400) are substantially orthogonal to the optical axis of the primary particle-optical beam path (13) and wherein the magnetic fields are substantially homogeneous. [8] Particle-optical arrangement according to the preceding claim, wherein the following relation applies to a sum SUM=(S1 / R1) + (S2 / R2): 0.60≤SUM≤0.80, in particular 0.65≤SUM≤0.75, where R1 denotes the radius and S1 the arc length of the primary particle-optical beam path (13) in the first magnetic field region (410), and where R2 denotes the radius and S2 the arc length of the primary particle-optical beam path (13) in the second magnetic field region (430). [9] Particle-optical arrangement according to one of claims 7 to 8, wherein during operation of the particle-optical arrangement, the following relation applies to the path of the primary particle-optical beam path (13) in the first magnetic field region (410) and in the second magnetic field region (430) for a ratio V = (S2 / R2) / (S1 / R1): 0.7≤V≤0.9, in particular 0.75≤V≤0.85, where R1 denotes the radius and S1 the arc length of the primary particle-optical beam path (13) in the first magnetic field region (410), and where R2 denotes the radius and S2 the arc length of the primary particle-optical beam path (13) in the second magnetic field region (430). [10] Particle-optical arrangement according to one of the preceding claims, wherein a first drift region (405) which is free of magnetic fields is arranged in the primary particle-optical beam path (13) between the first magnetic field region (410) and the second magnetic field region (430). [11] Particle-optical arrangement according to the preceding claim, wherein the drift region (405) has a length LD for which the following relation applies: LD≥8 cm, especially LD≥10 cm. [12] Particle-optical arrangement according to one of the preceding claims, wherein a total height of the magnet arrangement (400), which is defined by a distance between the entry point of the primary particle-optical beam path (13) into the second magnetic field region (430) and the exit point of the primary particle-optical beam path (13) from the first magnetic field region (410), is less than or equal to 1.0 m, in particular less than or equal to 0.5 m or less than or equal to 0.3 m. [13] Particle-optical arrangement according to one of the preceding claims, wherein the first magnetic field region (410) comprises two mutually parallel plates (481, 482) with a plate spacing D1 between them, between which a homogeneous magnetic field is generated during operation of the particle-optical arrangement, wherein the entry region of the first magnetic field region (410) is linear and has a width BE1, wherein the following relation applies to a ratio VPE1 = BE1 / D1: VPE1 ≥ 2.5, in particular VPE1 ≥ 3.0 or VPE1 ≥ 3.5; and / or wherein the exit region of the first magnetic field region (410) is linear and has a width BA1, wherein for a ratio VPA1 = BA1 / D1 the following relation applies: VPA1 ≥ 2.5, in particular VPA1 ≥ 3.0 or VPA1 ≥ 3.

5. [14] Particle-optical arrangement according to one of the preceding claims, wherein the second magnetic field region (430) comprises two mutually parallel plates (491, 492) with a plate spacing D2 between them, between which a homogeneous magnetic field is generated during operation of the particle-optical arrangement, wherein the entry region of the second magnetic field region (430) is linear and has a width BE2, wherein the following relation applies to a ratio VPE2 = BE2 / D2: VPE2 ≥ 2.5, in particular VPE2 ≥ 3.0 or VPE2 ≥ 3.5; and / or wherein the exit region of the second magnetic field region (430) is linear and has a width BA2, wherein for a ratio VPA2 = BA2 / D2 the following relation applies: VPA2 ≥ 2.5, in particular VPA2 ≥ 3.0 or VPA2 ≥ 3.

5. [15] Particle-optical arrangement according to one of the preceding claims, wherein the magnet arrangement (400) has a beam tube arrangement (490) within which the primary particle-optical beam path (13) runs within the magnet arrangement (400), wherein during operation of the particle-optical arrangement the following relation applies to a fill factor F of the beam tube arrangement (490) within the magnet arrangement (400): F ≤ 55%, in particular F ≤ 35% or F ≤ 10%. [16] Particle-optical arrangement according to one of the preceding claims, wherein the following relation applies to a splitting angle γ by which the primary particle-optical beam path (13) is deflected in the first magnetic field region (410) during operation of the particle-optical arrangement: γ ≥ 14°, in particular γ ≥ 16° or γ ≥ 18°. [17] Particle-optical arrangement according to one of the preceding claims, wherein the entrance inclination φ1 of the first magnetic field region (410) is selected such that an exit angle η of the secondary particle-optical beam path (11) from this first magnetic field region (410) is limited to η ≤ 35°, in particular η ≤ 25° or η ≤ 15°. [18] Particle-optical arrangement according to one of the preceding claims, wherein the magnet arrangement (400) has at least one further magnetic field region (450) in the secondary particle-optical beam path (11). [19] Particle-optical arrangement according to the preceding claim, wherein the magnet arrangement (400) in the secondary beam path (11) after passing through the first magnetic field region (410) has at least two further magnetic field regions which are configured to precisely couple the particle-optical axis in the secondary beam path (11) with respect to offset and angle into a subsequent projection optics in the case of varying energy of secondary particles whose path forms the second particle-optical beam path (11). [20] Particle-optical arrangement according to claim 18, wherein the magnet arrangement (400) in the secondary beam path (11) after passing through the first magnetic field region (410) has at least six further magnetic field regions and / or quadrupole fields which are configured to precisely couple the particle-optical axis in the secondary beam path (11) with respect to offset and angle into a subsequent projection optics when the energy of secondary particles, the path of which forms the second particle-optical beam path (11), varies and additionally to enable paraxially stigmatic, paraxially distortion-free and paraxially dispersion-free imaging. [21] Particle-optical arrangement according to one of claims 18 to 20, wherein at least one of the further magnetic field regions (450, 460, 470) of the secondary particle-optical beam path (11) is arranged in a gap between the first magnetic field region (410) and the second magnetic field region (430) of the primary particle-optical beam path (13). [22] Particle-optical arrangement according to one of claims 18 to 21, further comprising a magnetic shielding wall (495) arranged between at least one of the magnetic field regions (430) of the primary particle-optical beam path (13) and at least one of the magnetic field regions (450) of the secondary particle-optical beam path (11). [23] Particle-optical arrangement according to one of the preceding claims, wherein the particle-optical arrangement is a multi-beam particle microscope (1) and wherein the particle-optical arrangement further comprises: a multi-beam particle generator configured to generate a first field of a plurality of charged first single particle beams (3); a first particle optics with a primary particle-optical beam path (13) which is configured to image the generated first individual particle beams (3) onto an object plane (101) so that the first individual particle beams (3) strike an object (7) at impact locations (5) which form a second field; a detection unit (209) having a plurality of detection areas forming a third field; a second particle optics with a secondary particle-optical beam path (11) configured to image second single-particle beams (9) emanating from the impact locations (5) in the second field onto the third field of the detection regions of the detection system (209); a magnetic and / or electrostatic objective lens (102) through which both the first (3) and the second single-particle beams (9) pass; and a controller (10) configured to control particle-optical components in the primary (13) and / or secondary particle-optical beam path (11) and / or components of the magnet arrangement (400), wherein the magnet arrangement (400) is arranged in the primary particle-optical beam path (13) between the multi-beam particle generator and the objective lens (102), and wherein the magnet arrangement (400) is arranged in the secondary particle-optical beam path (11) between the objective lens (102) and the detection unit (209). [24] Particle optical arrangement according to the preceding claim, wherein the particle-optical axis A of the objective lens (102) coincides with the direction of the particle-optical axis Z of the primary particle-optical beam path (13) upon exiting the first magnetic field region (410), and wherein the exit region of the first particle-optical beam path (13) from the first magnetic field region (410) is not orthogonal to the particle-optical axis A of the objective lens (102). [25] Particle-optical arrangement according to the preceding claim, wherein the following relation applies to a distance OLBS between the objective lens (102) and the exit region of the first magnetic field region: OLBS≤75mm, especially OLBS≤70mm. [26] Particle-optical arrangement according to one of claims 23 to 25, wherein the imaging of the plurality of first individual particle beams (3) into the object plane (101) is substantially distortion-free, and / or wherein the imaging of the first single particle beams (3) into the object plane (101) is substantially dispersion-free; and / or wherein the impact points (5) of the first individual particle beams (3) in the object plane (101) are astigmatic and round. [27] Particle-optical arrangement according to the preceding claim, wherein the imaging of the plurality of first individual particle beams (3) onto the object plane (101) has substantially no image field inclination. [28] Particle-optical arrangement according to one of claims 23 to 27, wherein the imaging of the first individual particle beams (3) into the object plane (101) is free of image field astigmatism. [29] Particle-optical arrangement according to the preceding claim, wherein all other second and third order aberrations in the object plane (101) amount to a maximum of only 1 nm, in particular a maximum of only 0.5 nm or a maximum of only 0.25 nm.

Images