Multi-beam particle beam system with electrostatic booster lens, method for operating a multi-beam particle beam system and associated computer program product

Abstract

A multi-beam particle beam system 1 with improved resolution and higher acquisition speed is revealed. For this purpose, an electrostatic booster lens 112 is arranged in an upper focal plane of the objective lens 102 at the level of the crossing region of the primary particle beams. The electrostatic booster lens 112 selectively increases the kinetic energy of the primary beams 3 significantly in the crossing region 108, thereby reducing the Coulomb interaction between the charged particles.

Description

Field of the invention

[0001] The invention relates to multi-beam particle beam systems that operate with a plurality of charged single-particle beams. Specifically, the invention relates to a multi-beam particle beam system with an electrostatic booster lens, a method for operating a multi-beam particle beam system, and an associated computer program product. 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 multiple semiconductor structures fabricated in layers on a wafer surface using planar integration techniques. Due to the manufacturing processes, semiconductor wafers typically have a flat surface. The feature size of the integrated semiconductor structures ranges from a few µm to critical dimensions (CD) of a few nanometers, with feature sizes becoming even smaller in the near future; it is expected that feature sizes or critical dimensions (CD) will correspond to the 3nm, 2nm, or even smaller technology nodes of the International Technology Roadmap for Semiconductors (ITRS) in the future. With the small feature sizes mentioned above, defects the size of the critical dimensions must be identified quickly and over a very large area.For several applications, the specification requirement for the accuracy of a measurement provided by an inspection device is even higher, for example, by a factor of two or an order of magnitude. For example, a semiconductor feature width must be measured with an accuracy of less than 1 nm, such as 0.3 nm or even less, and a relative position of semiconductor structures must be determined with an overlay accuracy of less than 1 nm, such as 0.3 nm or even less.

[0004] A recent development in the field of charged particle inspection systems or particle microscopes 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.

[0005] The bundle of electron beams, or more generally, charged single-particle beams, is generated by directing a primary charged particle beam onto a multi-aperture array comprising at least one multi-aperture plate with a plurality of openings. A portion of the charged particles of the primary charged particle beam impinges on the multi-aperture plate and is absorbed there; another portion of the primary charged particle beam penetrates the openings of the multi-aperture plate, forming a charged first single-particle beam in the beam path behind each opening, the cross-section of which is defined by the cross-section of the opening.

[0006] 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 sample stage. During illumination of the wafer surface with the charged first single-particle beams, interaction products, such as secondary electrons or backscattered electrons, emanate from the surface of the sample. Their starting points correspond to the locations on the sample / object 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.

[0007] 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 also includes at least one crossover plane of the primary or secondary charged single-particle beams. Furthermore, the prior art system includes detection systems to facilitate adjustment. The prior art multi-beam particle microscope comprises at least one collective beam deflector (deflection scanner) for collectively scanning a region of the sample surface using the plurality of primary single-particle beams to obtain a field of view of the sample surface.The bundle of primary single-particle beams is systematically scanned over the surface of the sample and an electron microscopic image of the sample is generated in the usual way for scanning electron microscopes.

[0008] 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.

[0009] Typically, the two most important parameters of a particle microscope, or more generally of a multi-beam particle beam system, are its resolution and its scanning speed. This is especially true for particle microscopes used in the semiconductor industry. The scanning speed is fundamentally a function of the beam current. Using a high beam current also allows for a high scanning speed, which enables faster image generation.

[0010] Unfortunately, higher beam currents generate more Coulomb interactions between the charged particles or particle beams. These Coulomb interactions are a source or cause of aberrations. Higher beam currents therefore reduce the resolution of a particle microscope.

[0011] In a multi-beam particle beam system, the two parameters of resolution and scanning speed are at least partially decoupled from each other by dividing the total beam current into a multitude of spatially spaced, charged individual particle beams. Compared to a single-beam particle beam system, the dependence of resolution on the total beam current is therefore weaker in a multi-beam particle beam system.

[0012] However, even in a multi-beam particle beam system operating with a single column, it is not possible to spatially separate the individual particle beams from one another along the entire illumination path. Instead, the laws of optics require that there be at least one crossover plane or region in the primary path where the charged individual particle beams cross or penetrate each other. In this crossover region – also called the pupil plane – more Coulomb interactions occur, which promotes the formation of aberrations, which in turn negatively impacts the resolution of the multi-beam particle beam system. Therefore, even in multi-beam particle beam systems, it is not possible to arbitrarily increase the total beam current, neither by increasing the individual beam currents nor by increasing the number of individual particle beams.

[0013] It is also fundamentally known that the strength of the Coulomb interaction depends on the electrical potential or kinetic energy of the charged particles. High kinetic energy reduces the occurring Coulomb interaction. State-of-the-art multi-beam particle beam systems therefore already operate with high electrical potentials and high kinetic energies of the particles within the column. For this purpose, a high voltage is applied to the particle source or a high-voltage potential is provided; the same essentially applies to the sample stage or the sample. For example, high voltages of approximately (+ / -) 25 kV, (+ / -) 28 kV, or (+ / -) 30 kV can be used there. The charged particles or particle beams are strongly accelerated in the region of the particle source, then move at a very high speed throughout the entire column, and are only decelerated again shortly before reaching the sample.Theoretically, it is therefore an option to further increase the high voltage applied to the particle source and the sample (in terms of magnitude). However, in practice, this poses difficulties, particularly in the area of ​​the sample or sample stage. Increasing the high voltage applied to the sample stage and thus to the sample is either technically impossible or very difficult to implement. Description of the invention

[0014] It is an object of the present invention to provide a multi-beam particle beam system with improved resolution without having to reduce the scanning speed. In particular, it is an object of the invention to further reduce aberrations caused by Coulomb interaction in the primary path of a multi-beam particle beam system operating with a single column. This reduction should also be technically simple to implement.

[0015] A further object of the invention is to vary the numerical aperture in the object plane during operation of the multi-beam particle beam system. The numerical aperture depends on the total beam current and the landing energy. If one of these variables is changed, the optimal numerical aperture, at which the resolution is optimal, also changes, which is why it is advantageous to be able to adjust or set the numerical aperture.

[0016] It is a further object of the invention to change a working distance or the position of the object plane relative to the objective lens without thereby changing the magnification or the telecentricity of the first individual particle beams upon impingement in the object plane.

[0017] The problem is / are solved by the subject matter of the independent patent claims. Advantageous embodiments of the invention are evident from the dependent patent claims.

[0018] A fundamental idea of ​​the invention is not to increase the kinetic energy of the charged first single-particle beams along the entire illumination column, but rather to increase the kinetic energy of the charged first single-particle beams only in sections, specifically at the location with the most critical Coulomb interactions, i.e., in the crossover region. This approach significantly reduces Coulomb interaction-induced aberrations and simultaneously avoids problems that would arise when applying an even higher (in magnitude) high voltage to the sample stage / sample, which can be of any type.To increase the kinetic energy in sections, an electrostatic booster lens is implemented in a way that does not entail highly complex changes of particle-optical imaging parameters, but on the contrary provides one or more additional degrees of freedom for adjusting the multi-beam particle beam system.

[0019] According to a first aspect of the invention, it relates to a multi-beam particle beam system having the following features: a particle source for emitting a charged particle beam, a multi-aperture arrangement comprising at least one multi-aperture plate having a plurality of through-openings, wherein the multi-aperture arrangement is configured to generate a first field of a plurality of charged first single-particle beams from the charged particle beam; a first particle optics with a first particle optical beam path, which is configured to image the generated first single particle beams onto a sample surface in the object plane, so that the first single particle beams strike the sample surface at impact locations that form a second field; a magnetic and / or electrostatic objective lens through which the first single particle beams pass; a sample stage for arranging a sample with a sample surface in the object plane; an electrostatic booster lens, wherein the first particle-optical beam path has a crossover region of the charged first single-particle beams, which crossover region is arranged in the region of an upper focal plane of the objective lens, and wherein the electrostatic booster lens is arranged in the region of this crossover region; a voltage supply unit; and a controller for controlling the multi-beam particle beam system, wherein the controller is configured to provide a booster high voltage VB by means of the voltage supply unit at the electrostatic booster lens such that the charged first single-particle beams pass through the crossover region in sections with a significantly increased kinetic energy, so that aberrations due to a Coulomb interaction of the single-particle beams within the crossover region are reduced.

[0020] 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.

[0021] The sample can be of any type. In this patent application, the term "sample" is used generally to refer to the substrate to be examined or processed. The term "sample" is therefore to be interpreted broadly. Examples of a sample include wafers, lithography masks, or mask blanks.

[0022] The voltage supply unit according to the invention can be designed in one or more parts. In particular, it can be modular, for example, with a module for providing a high voltage and a module for providing a low voltage. The terms high voltage and low voltage are used in this patent application as is customary in electrical engineering: In DC operation, a high voltage is defined as a voltage V > 1500 V. A low voltage is defined as V ≤ 1500 V. The low voltage provided to the multi-aperture arrangement according to a preferred embodiment of the invention is preferably an extra-low voltage, with V ≤ 120 V being the applicable low voltage in DC operation. It can also be ground potential.

[0023] According to the invention, the electrostatic booster lens is arranged in the region of the crossover area of ​​the charged first single-particle beams in the first particle-optical beam path. Ideally, the crossover area would be a crossover plane; in practice, this is not the case, so instead, it is referred to as a crossover area. The electrostatic booster lens is arranged in the region of this crossover area. It therefore acts on the charged first single-particle beams in the crossover area. The nature of this effect is relatively abrupt, which is indicated by the term "booster."The idea is to use the electrostatic booster lens to significantly increase the kinetic energy of the first single-particle beams over a relatively short section of the first particle-optical beam path, so that the first single-particle beams pass through the crossover region with significantly increased kinetic energy. As a result, aberrations due to Coulomb interaction of the first single-particle beams within the crossover region are significantly reduced.Furthermore, this increased kinetic energy is only present in certain sections, meaning that the electrostatic booster lens does not increase the kinetic energy of the charged individual particle beams for the entire remaining section of the particle-optical beam path up to the objective lens or the sample. Instead, the significantly increased kinetic energy is at least substantially reduced again immediately after passing through the crossover region. Thus, the electrostatic booster lens only significantly increases the kinetic energy of the charged first individual particle beams in certain sections.

[0024] According to a preferred embodiment of the invention, the first individual particle beams have their maximum kinetic energy in the region of the booster lens and thus in the crossover region in the particle-optical beam path between the particle source and the sample, whereby the following relationship applies to the maximum electrical potential increase ΔVB caused by the booster lens: ΔVB ≥ 10 kV, in particular ΔVB ≥ 15 kV. This maximum electrical potential increase ΔVB is very high compared to typical total potential changes in the particle-optical beam path. For example, it is possible that the electrical potential increase ΔVB caused by the electrostatic booster lens is ≥ 30%, ≥ 40%, or ≥ 50% of the potential difference that the charged particles, preferably electrons, have already experienced on their way from the particle source to entering the booster lens.For example, it is possible for a negative potential or a negative high voltage of -30 kV to be applied to the particle source. For example, before entering the booster lens, the electrons are approximately at ground potential and have a kinetic energy of 30 kV. Their kinetic energy can then be further increased by ≥ 10 kV or ≥ 15 kV using the booster lens, which corresponds to an increase of ≥ 1 / 3 or ≥ 50% of their kinetic energy, respectively.

[0025] According to a preferred embodiment of the invention, the controller is configured to provide a first high voltage V1 to the particle source by means of the voltage supply unit. Furthermore, the controller is configured to provide a maximum low voltage Um to the multi-aperture arrangement by means of the voltage supply unit, and the controller is configured to provide a second high voltage V2 to the sample stage and thus to the sample by means of the voltage supply unit.

[0026] According to a preferred embodiment of the invention, the first high voltage V1 and the second high voltage V2 have the same sign. In this embodiment, the first high voltage V1 at the particle source satisfies the following relationship in terms of magnitude: 20 kV ≤ V1 ≤ 40 kV, in particular 25 kV ≤ V1 ≤ 35 kV. Furthermore, the following relationship applies to the second high voltage V2 at the sample stage: 20 kV ≤ V2 ≤ 40 kV, preferably 25 kV ≤ V2 ≤ 35 kV. Furthermore, the following relationship applies to the low voltage Vm at the multi-aperture arrangement: 0 V ≤ Vm ≤ 100 V, preferably Vm = 0 V or ground potential. The identical sign of the first high voltage V1 and the second high voltage V2 is explained by the fact that the charged first single particle beams are initially accelerated but then decelerated again strongly before reaching the sample.Typical landing energies upon impact with the sample are several hundred eV, for example, 900 eV, 1.2 keV, or 1.5 keV. The high voltages V1 and V2 specified above, as well as the low voltage Vm or the ground potential at the multi-aperture arrangement, are voltages that have previously been applied to multi-beam particle beam systems in this way. The special feature of the present invention is that these values ​​do not have to be changed. This avoids problems that arise when applying an even higher high voltage, for example, at the sample stage. Furthermore, it is highly advantageous to keep the multi-aperture arrangement, or the so-called micro-optics, at ground potential. This avoids problems, particularly with the electronics and their control.Nevertheless, the electrostatic booster lens makes it possible to harden the charged first single-particle beams in the crossover region to reduce Coulomb interactions. The use of a booster lens is therefore a very elegant solution compared to a solution that would require ever-increasing high voltages at both the particle source and the sample stage.

[0027] According to a preferred embodiment of the invention, the booster high voltage VB has a different sign than the first and second high voltages, with the booster high voltage VB at the electrostatic booster lens satisfying the following relationship in terms of magnitude: VB ≥ 10 kV, in particular VB ≥ 15 kV. Thus, if the particle source and sample stage are at a negative high-voltage potential, a positive high-voltage potential is present at the electrostatic booster lens according to this embodiment of the invention. This embodiment further substantiates the fundamental advantages of the electrostatic booster lens arrangement described above.

[0028] According to a further preferred embodiment of the invention, the following relationship applies to a length LB of the electrostatic booster lens along the particle-optical axis Z: 2 mm ≤ LB ≤ 10 mm. The electrostatic booster lens or its lens field therefore has only a very small extent along the particle-optical axis Z, which means that the section-by-section increase in the kinetic energy of the charged first individual particle beams and also their re-deceleration occur over a very short distance. The length LB of the electrostatic booster lens is measured along the extent of the effectiveness of the electrostatic booster lens, which essentially corresponds to the distance between the electrodes or counterelectrodes of the electrostatic booster lens. According to a further preferred embodiment of the invention, the following relationship applies to a length LBm of a central electrode of the electrostatic booster lens: 1.5 mm ≤ LBm ≤ 4.5 mm.

[0029] According to a preferred embodiment of the invention, the electrostatic booster lens is functionally essentially designed as a single lens. A characteristic of a single lens is that the charged particles have the same kinetic energy upon entering and exiting the single lens. They are merely accelerated within the single lens. This applies to the electrostatic booster lens, at least in principle, so that a significant increase in kinetic energy and also a subsequent decrease in it can be achieved in sections of the crossover region. This ensures the booster function. However, it is possible that the counter electrodes of the "single lens" are not at exactly the same potential. This offers advantages for correcting particle-optical imaging parameters. Details on this will be discussed in more detail below.

[0030] According to a preferred embodiment of the invention, the lens effect of the electrostatic booster lens is at least partially realized by means of an offset voltage at a multipole electrode. This offset voltage at a multipole electrode, for example a quadrupole, octupole, or twelve-pole electrode, can also be used to adjust the lens effect of the multipole electrode. An offset voltage is preferably applied to a multipole electrode(s) to create a counterelectrode(s). However, it is also possible to apply an offset voltage to a multipole electrode to create the center electrode of a single lens. These embodiments make it possible to utilize multipole electrodes already arranged in the crossover region for the design of the electrostatic booster lens.For example, a collective scanning deflector is provided in the region of the beam crossing or in the region of the crossing area, which may comprise corresponding multipole electrodes for the collective deflection of the first individual particle beams.

[0031] According to a preferred embodiment of the invention, the multi-beam particle beam system comprises a beam tube arrangement within which at least the first individual particle beams are guided at least in sections, and wherein the beam tube arrangement comprises a beam tube extension that projects into the objective lens. The electrostatic booster lens is arranged within this beam tube extension. In this embodiment of the invention, the electrostatic booster lens can be designed, for example, as a single lens with a first electrode, a second (middle) electrode, and a third electrode. It is preferred that the beam tube extension be substantially at ground potential.

[0032] According to an alternative embodiment of the invention, the multi-beam particle beam system comprises a beam tube arrangement within which at least the first individual particle beams are guided, at least in sections. The beam tube arrangement has a beam tube interruption in the region of the crossover area, and the beam tube arrangement is subdivided into a first beam tube section and a second beam tube section by means of the beam tube interruption. According to this embodiment, a first upper electrode of the electrostatic booster lens can then be formed by means of the first beam tube section, to which a maximum low voltage VT1 is applied. Furthermore, a second middle electrode of the electrostatic booster lens can be arranged within the beam tube interruption, to which the booster high voltage VB is provided.Furthermore, a third lower electrode of the electric booster lens can be formed by means of the second beam tube section, to which a maximum low voltage VT2 is applied. The low voltages VT1 and VT2 can be identical, but they can also differ from each other. According to this embodiment of the invention, the electrostatic booster lens can again be functionally designed in a very simple manner, essentially as a single lens. The manufacture of this electrostatic booster lens is also very simple in terms of design.

[0033] According to a preferred embodiment of the invention, the multi-beam particle beam system comprises a collective scan deflector with an upper deflection unit in the upper crossover region and a lower deflection unit in the lower crossover region. The crossover plane, i.e., the idealized plane of beam crossing, is located between the upper and lower crossover regions. According to this embodiment of the invention, the middle electrode of the electrostatic booster lens is arranged between the upper deflection unit and the lower deflection unit. The electrostatic booster lens is therefore located with its middle electrode very centrally in the crossover region, or at the level of the theoretical crossover plane. As a result, the electrostatic booster lens acts very precisely in the crossover region of the individual particle beams.A counter potential to the middle electrode in the form of an offset voltage can be applied to the upper deflection unit and to the lower deflection unit.

[0034] The provision of an electrostatic booster lens in the crossover region, or as precisely as possible at the level of the crossover, has another advantage and another important consequence: In multi-beam particle beam systems, particle-optical imaging parameters cannot be adjusted independently of one another. A change in one parameter usually requires the adjustment of another. However, in the crossover region of the first individual particle beams, particle-optical imaging parameters are at least largely decoupled from one another.The electrostatic booster lens essentially only influences the α-beam or axial beam and thus the focusing of the first individual particle beams, while the γ-beam or field beam passes through the system's axis of symmetry and is thus essentially unaffected by the electrostatic booster lens. The provision of an electrostatic booster lens in the crossover region therefore has manageable consequences for the imaging properties of the multi-beam particle beam system and does not lead to a complete misalignment of the entire system. Instead, the electrostatic booster lens essentially causes a slightly changed focusing of the first individual particle beams as they leave the electrostatic booster lens. This changed focus position can be corrected or adjusted relatively easily.

[0035] According to the invention, it is now even possible to design the multi-beam particle beam system not only once for a specific booster high voltage or booster voltage VB, but even to vary this booster voltage and to use it for the purpose of setting a changed numerical aperture NA of the first individual particle beams upon impact in the object plane.

[0036] According to a preferred embodiment of the invention, the multi-beam particle beam system further comprises a first adjustment means, wherein the controller is configured to actuate the first adjustment means so that the booster high voltage VB applied to the electrostatic booster lens is changed. This, in turn, changes a working distance WD of the first individual particle beams and / or a numerical aperture NA of the first individual particle beams upon impact in the object plane.

[0037] According to a further preferred embodiment of the invention, the multi-beam particle beam system further comprises a second adjustment means that is different from the first adjustment means, and the controller is configured to actuate the second adjustment means so that the changed working distance WD of the first individual particle beams is corrected and / or so that the changed numerical aperture NA of the first individual particle beams upon impingement in the object plane is corrected. It is therefore possible to use the second adjustment means to keep particle-optical properties constant that would otherwise change due to the changed setting of the electrostatic booster lens. However, such a correction is naturally unnecessary if the changed setting of the electrostatic booster lens is intentionally used to change the particle-optical parameters.The electrostatic booster lens then provides an additional degree of freedom for the adjustability of particle-optical imaging parameters. In particular, it can be used to specifically adjust the numerical aperture (NA) and thus optimize the resolution. Details on degrees of freedom and their use in adjusting particle-optical imaging parameters, and in particular the numerical aperture, can be found, for example, in international patent application WO 2021 / 018332 A1, the disclosure of which is incorporated in its entirety by reference into the present patent application.

[0038] The second adjustment means, which differs from the first adjustment means, can be configured in different ways. It can be a single-piece or multi-piece design. It is possible to provide separate second adjustment means for the multi-beam particle beam system, but it is also possible to use existing particle-optical elements of the multi-beam particle beam system as the second adjustment means or to control them accordingly.

[0039] According to a preferred embodiment of the invention, the second adjustment means is configured to effect a changed excitation of the objective lens and / or a field lens. If one considers the first particle-optical beam path from an intermediate image plane to the object plane, this essentially corresponds to a 4f system. Two focal lengths f1 can be provided, for example, by means of a field lens, and two further focal lengths f2 by means of the objective lens of the multi-beam particle beam system. The electrostatic booster lens is located in the crossover region and thus essentially at the level of the so-called pupil plane. The imaging properties of the so-called 4f system can be maintained as long as a focal length of the objective lens and a focal length of the field lens are changed simultaneously.It is then possible for the overall system to remain telecentric, the image scale changes only insignificantly, and its change can be tolerated. Furthermore, the pupil plane remains essentially fixed, and the position of the electrostatic booster lens remains in the crossover region. The objective lens and the field lens can, in particular, be magnetic lenses, whose excitation change can be achieved by changing the corresponding lens current.

[0040] A change in the refractive power of the objective lens can, in principle, also be achieved by means other than changing the excitation of the objective lens. In principle, this can be achieved by using elements that change the speed of the charged particles of the first single-particle beams within the magnetic field of the objective lens, which in turn can vary the objective lens's refractive power.

[0041] According to a preferred embodiment of the invention, the second adjustment means is configured to effect a modified control of the collective scanning deflector. A slightly modified offset potential can be applied to the upper and / or lower deflectors of the collective scanning deflector, which induces a corresponding lensing effect and, with modified offset potentials, causes a velocity change, which in turn changes the refractive power of the objective lens for these individual particle beams. The offset voltage differs from a voltage applied to a beamline.

[0042] According to a further preferred embodiment of the invention, the second adjustment means is configured to apply a modified voltage VT2 to the second beam tube section. This also results in a modified lens effect and a modified velocity within the magnetic field of the objective lens.

[0043] According to a further preferred embodiment of the invention, the second adjustment means comprises an electrostatic correction element arranged in a / the magnetic field of the objective lens. This can be, for example, an autofocus correction lens and / or a multipole corrector.

[0044] According to a further embodiment of the invention, the second adjustment means can be configured not to change the focal length of the objective lens, but only to adjust the focal length of a field lens. With respect to the 4f system mentioned above, the originally telecentric system is thereby transformed into a non-telecentric system. Accordingly, adjusting the input telecentricity of the individual particle beams upon entry into the 4f system is an adjustment option or correction option.

[0045] According to a preferred embodiment of the invention, the multi-beam particle beam system further comprises an intermediate image plane and a telecentricity correction means, in particular an additional field lens, in the first particle-optical beam path. The telecentricity correction means is arranged between the multi-beam generator and the intermediate image plane. The controller is configured to control the telecentricity correction means, in particular the additional field lens, so that an input telecentricity of the first individual particle beams in the intermediate image plane is varied.

[0046] In both cases (change of both objective lens focal length and field lens focal length or no change of objective lens focal length and only change of field lens focal length) an extraction field between the objective lens and the sample can remain unchanged.

[0047] According to a preferred embodiment of the invention, the multi-beam particle beam system is configured for telecentric impingement of the first individual particle beams in the object plane. This is particularly advantageous for semiconductor samples with high-voltage structures, but it can also be advantageous for other samples.

[0048] According to a preferred embodiment of the invention, the multi-beam particle beam system further comprises: a detection system having a plurality of detection areas forming a third field; a second particle optics with a second particle optical beam path, which is configured to image second single particle beams emanating from the impact locations in the second field onto the third field of the detection areas of the detection system; a beam switch arranged in the first particle-optical beam path between the multi-aperture arrangement and the objective lens, and arranged in the second particle-optical beam path between the objective lens and the detection system, whereby the second single particle beams also pass through the objective lens.

[0049] According to a preferred embodiment of the invention, the multi-beam particle beam system is an inspection system, in particular a multi-beam particle microscope. According to an alternative embodiment of the invention, the multi-beam particle beam system is a lithography system. Lithography systems can be used, for example, to produce lithography masks or wafers using direct-write lithography. However, the multi-beam particle beam system according to the invention can also be of a different type.

[0050] The above-described embodiments of the invention according to the first aspect may be combined in whole or in part with one another, provided that no technical contradictions arise.

[0051] According to a second aspect of the invention, it relates to a method for operating a multi-beam particle beam system, in particular a multi-beam particle beam system as described above in several embodiments. The method comprises the following steps: (a) providing a multi-beam particle beam system having a crossover region of charged first single particle beams in the illumination path in an upper focal plane of an objective lens; and (b) significantly increasing the kinetic energy of the first single-particle beams in the crossover region in sections to significantly reduce the Coulomb interaction between the charged first single-particle beams. This can be achieved, in particular, by implementing an electrostatic booster lens in the crossover region, as has already been described in several embodiments in connection with the first aspect of the invention.

[0052] According to a preferred embodiment of the invention, the method further comprises the following steps: (c) changing the maximum kinetic energy of the first single-particle beams in the crossover region, whereby at least one imaging parameter of the multi-beam particle beam system is changed upon impingement of the first single-particle beams in an object plane; and (d) Correcting the at least one changed imaging parameter. This imaging parameter can be, for example, the changed working distance WD or the numerical aperture NA of the first single particle beams upon impact in the

[0053] Object plane. Additionally or alternatively, particle-optical parameters such as telecentricity or magnification can be set or adjusted.

[0054] Furthermore, everything already stated in connection with the first aspect of the invention also applies in connection with the second aspect of the invention. This particularly applies to definitions and advantageous embodiments.

[0055] According to a third aspect of the invention, this relates to a computer program product with program code for carrying out the method as described above in connection with the second aspect of the invention. The program code can be written in any programming language. The program code can be designed in one or more parts. In particular, it is advantageous to provide separate program code for controlling the electrostatic booster lens. However, this does not have to be the case; the program code can also be structured differently.

[0056] The invention will be better understood with reference to the accompanying figures, in which: Fig. 1: shows a schematic representation of a multi-beam particle beam system using the example of a multi-beam particle microscope; Fig. 2: shows a schematic section of the illumination column of the multi-beam particle beam system from Fig. 1 together with a schematic representation of the kinetic energy of primary rays traveling through the lighting column; Fig. 3: shows schematically an image sensor of the multi-beam particle beam system from Fig. 1; Fig. 4: shows a schematic of an electrostatic booster lens and its control as well as its influence on the kinetic energy of the charged particles passing through it; Fig. 5: shows a schematic diagram of an electrostatic booster lens and its control as well as its influence on the kinetic energy of the charged particles passing through it; Fig. 6: shows schematically an arrangement of an electrostatic booster lens in a multi-beam particle beam system; Fig. 7: shows schematically an electrostatic booster lens and its control as well as its influence on the kinetic energy of the charged particles traveling through it when the booster lens is arranged according to Fig. 6; Fig. 8: shows schematically an arrangement of an electrostatic booster lens in a multi-beam particle beam system; Fig. 9: shows a schematic of a 4f system with an electrostatic booster lens in a crossover region and its influence on the particle-optical beam path; and Fig. 10: shows schematically a flow diagram of a method according to the invention.

[0057] In the exemplary embodiments of the invention described below, components with similar functions and structures are designated by similar or identical reference numerals wherever possible. Elements of an array, for example, the plurality of first charged single-particle beams, may be designated by a single reference numeral. Depending on the context, the same reference numeral may also designate an individual element of the array. Each charged first single-particle beam (3.1, 3.2, 3.3) is a single-particle beam or "beamlet" of the plurality of charged first single-particle beams (3).

[0058] The schematic representation in Fig. Figure 1 shows basic features and functions of a multi-beam particle beam system 1. It is noted that the symbols used within the figure have been selected based on the respective functionality they symbolize. The type of system 1 shown is that of a multi-beam particle microscope 1. However, the invention is not limited to multi-beam particle microscopes; the representation in Fig. 1 is for illustrative purposes only. The multi-beam particle beam system 1 operates with a plurality of charged first single-particle beams 3 to generate a corresponding plurality of impact locations or beam spots 5 of the first single-particle beams on a surface 25 of an object 7, wherein the object 7 or the sample 7 can be, for example, a wafer or a mask substrate arranged with its surface 25 in an object plane 101 of an objective lens 102. For reasons of simplicity, only three charged first single-particle beams 3.1 to 3.3 and correspondingly three impact locations 5.1 to 5.3 of the charged first single-particle beams in the object plane 101 are shown. The features and functions of the multi-beam particle beam system 1 can be implemented using electrons or other charged particles such as ions and in particular helium ions.Further details about the multi-beam particle beam system 1 are disclosed in international patent application WO 2021 / 018332 A1, filed on June 16, 2021. The disclosure of this patent application is incorporated in its entirety by reference into the present patent application.

[0059] The multi-beam particle beam system 1 comprises an object illumination unit 100 and a detection unit 200 as well as a beam switch 400 for separating a secondary particle-optical beam path 13 from a first particle-optical beam path 11. The object illumination unit 100 comprises a beam generation device 300 for generating a plurality of charged first single-particle beams 3 and is adapted to focus the plurality of charged first single-particle beams 3 into the object plane 101, in which the surface 25 of an object 7 or wafer 7 is positioned by means of a sample stage 500.

[0060] The beam generating device 300 generates a plurality of charged first single-particle beam spots in an intermediate image plane 321. The beam generating device 300 comprises at least one source 301 of charged particles, for example, electrons. The at least one particle source 301 emits a divergent charged particle beam, which is collimated by at least one collimating lens 303 to form a collimated or parallel first charged particle beam 309. The collimating lens 303 typically comprises one or more electrostatic or magnetic lenses, or a combination of electrostatic and magnetic lenses. The collimated primary charged particle beam 309 impinges on the multi-beam generator 305.A multi-beam generator 305 is described, for example, in US 2019 / 0259575 A1 and in US 10 741 355 B1; both publications are incorporated in their entirety by reference into the present patent application. The multi-beam generator 305 essentially comprises a first multi-aperture plate or filter plate 304, which is illuminated by the then collimated first particle beam 309. The first multi-aperture plate or filter plate 304 has a plurality of apertures in a grid arrangement for generating the plurality of charged first single-particle beams 3, wherein these charged first single-particle beams 3 are formed when charged particles of the charged first particle beam 309 pass through the corresponding openings.The multi-beam generator 305 further comprises at least one further multi-aperture plate 306, which is arranged downstream of the first multi-aperture plate or filter plate 304 in the direction of the particle-optical beam path. The direction of the particle-optical beam path is determined by the direction of movement of the charged particles of the particle beam 309. According to one example, a second multi-aperture plate 306 can have four or eight electrostatic elements for each of the plurality of openings, for example, to individually deflect each of the first single-particle beams 3. Together with a second field lens 303, the plurality of charged first single-particle beams 3 are focused into the intermediate image plane 321 or in its immediate vicinity. The charged particle source 301 and each of the active multi-aperture plates 306 are controlled by the primary path control module 830, which is part of the controller 800 of the multi-beam particle beam system 1.

[0061] The plurality of focal points of the charged first single-particle beams 3 passing through the intermediate image plane 321 are imaged into the object plane 101 by means of a field lens group 103 and an objective lens 102, in which the surface 25 of the object 7 is positioned. An electrostatic deceleration field is generated between the objective lens 102 and the object surface 25 by applying a voltage to the object 7 via a sample voltage supply 503. By means of the electrostatic deceleration field generated by the sample voltage supply 503, a landing energy EL of the charged first single-particle beams, for example, primary electrons, is adjusted, for example, to less than 1 keV, less than 800 eV, less than 500 eV, less than 300 eV, or even less.

[0062] Fig. Figure 2 schematically illustrates further details of the electrostatic deceleration field. A plurality of charged single-particle beams 3 are generated from the collimated electron beam 309 by means of the multi-aperture arrangement 305 or by means of the multi-beam generator 305. For reasons of simplicity, only three single-particle beams 3.1 to 3.3 are shown, but more charged first single-particle beams 3 can naturally be generated, for example, more than 60, more than 90, or even more than 300 single-particle beams. A beam tube 151, in which the plurality of single-particle beams 3 are guided, is arranged downstream of the multi-aperture arrangement 305 in the direction of the particle-optical beam path 11. This beam tube 151 is connected to a voltage supply that provides a beam tube voltage VT.From the time they enter the beam tube 151 until they exit the beam tube 151 through the beam exit opening 153, the charged first single-particle beams 3 have a constant kinetic energy ET. The kinetic energy ET of the charged first single-particle beams 3 or electron beams during their passage through the beam tube 151 is, for example, 20 keV, 30 keV, or 35 keV.

[0063] The plurality of first individual particle beams 3 are imaged, and beam spots 5.1 to 5.3 are formed in the image plane 101 or object plane 101 by means of field lenses 333 and 103 and by means of the objective lens 102. In the example shown, the objective lens 102 is a magnetic lens with a winding 161 and a pole piece 163 with a lower pole piece segment 165, wherein the lower pole piece segment 165 forms a gap in the axial direction for the magnetic field of the magnetic lens 163. A current I is provided during operation of the winding 161 to generate the focusing magnetic field (not shown). Other types of magnetic lenses are also possible, for example, lenses with a radial gap for generating an immersion lens field or magnetic lenses with multiple windings and pole pieces.A beam splitter 400 is arranged above or partially integrated into the magnetic lens 102. This beam splitter is configured to separate the secondary electrons 9 or second charged single-particle beams 9 along the secondary particle-optical beam path 13 and guide them to the detection unit 200. An electrode 133 is provided below the lower pole shoe segment 165, which is connected to a voltage supply so that a second voltage VE is provided at the electrode 133. In the example shown, the electrode 133 is designed as a separate electrode.

[0064] After leaving the beam tube 151, the plurality of charged first single-particle beams 3 are decelerated from the kinetic energy ET to the second kinetic energy EE. The voltage difference between VT and VE is responsible for the generation of the first electric field 135, which Fig. 1 is represented by two equipotential lines of the first electric field 135. The associated vectors of the electric field are substantially parallel to the propagation direction of the charged first single-particle beams 3 and generate a deceleration force on the charged first single-particle beams 3. The first voltage VE is typically adjusted such that the second kinetic energy EE is in a range of less than 5 keV, less than 3 keV, or even less than 2 keV. A third sample voltage VL is supplied by the voltage supply unit 503 to the sample support plate 505, which serves to hold and contact the sample 7 during operation of the multi-beam particle beam system 1.According to the voltage difference between VL and VE, a second electric field 137 is generated, which is almost parallel to the propagation direction of the charged first single-particle beams 3 and exerts a deceleration force on the charged first single-particle beams 3 or the associated particles. The third or sample voltage VL is adjusted such that the third kinetic energy or landing energy EL of the primary single-particle beams 3, for example, electrons in the described example, is in a range of < 800 eV, < 300 eV, or even < 100 eV. The electric fields 135 and 137 both form a deceleration field to reduce the kinetic energy of the charged first single-particle beams 3 before they impact the sample surface 25, which is arranged in the object plane 101.The first electric field 135 also forms an acceleration field for the second single-particle beams 9 or secondary electrons 9 emerging from the sample 7 or wafer 7. The second electric field 137 forms an extraction field for extracting and accelerating secondary particles or secondary electrons from the sample 7 or wafer 7. The second electric field 137 is therefore also referred to as the extraction field 137.

[0065] The Fig. The example shown in Figure 2 shows a two-stage deceleration field 135 and 137 as well as an additional electrode 133. In another example, only one deceleration field or extraction field 137 may be provided, which is generated between the beam exit opening 153 of the beam tube 151 on the one hand and the sample 7 on the other hand, which is arranged on the sample receiving plate 505. In this case, the exit opening 153 of the beam tube 151 plays the role of the electrode 133 for the extraction field 137.

[0066] The object illumination unit 100 of the multi-beam particle beam system 1, which is installed in the Fig. 1 and Fig. 2, further comprises a collective beam deflector 110 near a crossover region 108 of the charged single-particle beams 3. By means of the collective beam deflector 110, the charged first single-particle beams 3 can be collectively deflected in a scanning direction 143, wherein the scanning direction 143 is orthogonal to the propagation direction of the charged single-particle beams 3. The propagation direction of the charged first single-particle beams in each of the described examples is in the positive z-direction. Both the objective lens 102 and the collective scanning deflector 110 are centered on an optical axis Z (not shown) of the multi-beam particle beam system 1, which is perpendicular to the sample surface 25 or wafer surface 25, respectively.The plurality of charged first single-particle beams 3, which form the beam spots 5 according to a grid arrangement, are synchronously scanned across the wafer surface 25 or sample surface 25. According to one example, the grid arrangement of the beam spots 5 of the plurality of charged first single-particle beams 3 is a hexagonal grid of approximately 100 or more charged first single-particle beams 3, for example, 91 beams, 100 beams, or even 300 or more beams. The beam spots 5 have a mutual spacing of approximately 6 µm to 45 µm and a diameter of less than 5 nm, for example, 3 nm, 2 nm, or even less. According to one example, the size of a beam spot is approximately 3 nm, and the spacing between adjacent beam spots is approximately 8 µm.At each scanning position of the charged first single-particle beams and thus in the region of the beam spots 5, a plurality of secondary electrons is generated, each forming a plurality of charged second single-particle beams 9 or charged secondary electron beams 9, respectively, in the same grid configuration as the beam spots 5. The intensity of the secondary electron beams 9 formed at each beam spot or illumination spot 5 depends on the intensity of the incident charged first single-particle beams 3 illuminating the spot 5, the material compositions 67, 69 and the topography of the object 7 beneath the respective illumination spot 5, as well as the charge state of the sample 7 at the illumination spot 5.The plurality of charged second single-particle beams 9 are accelerated by the same electrostatic field between the objective lens 102 and the object surface 25 and are collected by the objective lens 102. The secondary beams 9 pass through the first collective scanning deflector 110 in the opposite direction to the primary single-particle beams 3. The plurality of charged second single-particle beams 9 are collectively deflected by the collective scanning deflector 110. The plurality of charged second single-particle beams 9 are then deflected by the beam splitter 400 to follow the second particle-optical beam path 13 toward the detection unit 200.The plurality of charged second single electron beams 9 move in the opposite direction to the charged first single particle beams 3, specifically with the kinetic energy ES = ET - EL, and the beam switch 400 is configured to separate the second particle-optical beam path 13 from the primary particle-optical beam path 11 by means of magnetic fields or by means of a combination of magnetic field and electrostatic field.

[0067] The detection unit 200 images the second single-particle beams 9 or secondary electron beams 9 onto an image sensor 600, forming a plurality of second charged image spots 15. The detector or image sensor 600 comprises a plurality of detection pixels or individual detectors. For each of the second charged beam spots 15, the intensity is detected separately, and the property of the object surface 25 is recorded with high resolution for a large image field of the object 7 with a high throughput. For example, with a grid of 10 × 10 single-particle beams 3 with a pitch of 8 µm, an image field of approximately 88 µm × 88 µm can be scanned by means of an image scanning process using the collective scanning deflector 110, with an image resolution of, for example, 2 nm or better.The image field is scanned with half the beam spot size, thus with a number of 800 pixels per image line for each individual particle beam 3, so that the generated image field, generated using 100 individual particle beams 3, comprises approximately 6.4 gigapixels. The digital image data is collected by the controller 800. Details regarding the image data collection and image data processing, for example, using parallel data processing, are described in the international patent application WO 2020 151 904 A2 and in the US patent US 9 536 702 B2, the contents of which are each incorporated in their entirety by reference into the present patent application.

[0068] The detection unit 200 further comprises at least one second collective scan deflector 222, which is connected to the scan deflector control module 860. The scan deflector control module 860 is configured to compensate for a deviation in the deflection force of the first collective scan deflector 110 in the common particle-optical beam path, so that the positions of the second individual particle beams 9 upon impingement on the image sensor 600, thus the beam spots 15, are kept constant. The difference in the collective deflection according to the first collective scan deflector 110 arises from the different kinetic energies ET of the first individual particle beams 3 compared to the kinetic energy ES of the second individual particle beams 9. The multi-beam particle beam system 1 can further optionally comprise a retractable monitoring system 230.Monitoring systems and methods for detecting charging effects on charged samples are described in more detail in patent applications PCT / EP2022 / 061042 and DE 10 2022114923.4, each of which is incorporated in its entirety by reference into the present patent application. The detection unit 200 is described in more detail below.

[0069] The image sensor 600 is configured by an arrangement or an array of detection areas arranged in a pattern that is compatible with or corresponds to the grid arrangement of the second individual particle beams that are focused onto the image sensor 600 by the detection unit 200. This enables the detection of each second individual particle beam 9 independently of the other second individual particle beams 9 upon impingement on the image sensor 600. The image sensor 600, which is Fig. 1, can be an electron-sensitive detection array, for example a CMOS detector or a CCD sensor. Such an electron-sensitive detection array can comprise an electron-photon conversion unit, for example a scintillation element or an array or grid of scintillation elements. In another embodiment, the image sensor 600 can be designed as an electron-photon conversion unit, which is arranged in the focal plane of the second single-particle beams 9 or the formed beam spots 15. In this embodiment, which is shown by way of example in Fig. 3, the image sensor 600 may further comprise an optical relay system comprising converging lenses 605 and a zoom lens 611 for imaging and guiding the photons generated at the impact points 15 by the electron-photon conversion unit 602 to special photodetection elements 623, for example, a plurality of photomultipliers or avalanche photodiodes. Such an image sensor 600 is disclosed, for example, in US Pat. No. 9,536,702 B2, which was cited above and is incorporated in its entirety by reference into the present patent application. In the described example, the image sensor 600 is further provided with an optionally retractable monitoring system 230 comprising a beam splitter mirror 237, an imaging lens 235, and a high-resolution CMOS sensor 232.

[0070] During the acquisition of an image field by scanning the sample 7 using the plurality of charged first single-particle beams 3, the sample stage 500 is preferably not moved. After the acquisition of an image field, the sample stage 500 is moved and the next image field is acquired. According to an alternative implementation, the sample stage 500 is continuously moved in a second direction while an image is acquired by scanning the plurality of charged single-particle beams 3 with the collective scanning deflector 110 in a first direction. The movement of the sample stage 500 and the position of the sample stage 500 are monitored and controlled using known sensor technology, for example, using laser interferometers, grating interferometers, confocal microlens arrays, or the like.

[0071] During image acquisition, the controller 800 is configured to trigger the image sensor 600 to record a plurality of temporally corresponding intensity signals from the plurality of second single-particle beams 9 at predetermined time intervals, and the digital image of an image field is collected and stitched together (so-called "stitching") from all scanning positions of the plurality of first single-particle beams 3.

[0072] The controller 800 of the multi-beam particle beam system 1 further includes an image control module 810 configured to receive a data stream from the image sensor 600 and generate a digital image of the surface of the sample 7 during operation. The controller further includes a secondary path control module 840 configured to control the detection unit 200. The controller 800 further includes a primary path control module 830 configured to control the elements of the object illumination unit 100. The controller 800 further includes a sample stage control module 850 configured to control the positioning and orientation of the sample stage and to control the supply of voltage by the voltage supply module 503.The controller 800 further comprises a scan deflector control module 860 configured to control a scanning operation using the first collective scan deflector 110 and the second deflection system 222. Furthermore, the controller 800 comprises a processor 880 for the controller, which is configured to control inspection tasks for the samples 7 and is further configured to control the modules 810, 820, 830, 840, 850, 860, as well as a memory 890 for storing software, work instructions, and image data. The processor 880 for the controller 800 is further connected to a user interface IX for exchanging data, work instructions, software, or user interactions.

[0073] The controller 800 of the multi-beam particle beam system 1 further includes a contrast control module 870 connected to the processor 880 for the controller 800. The contrast control module 870 is configured to receive instructions from the processor 880 for the controller to compensate for charging effects during the imaging of the second single-particle beams 9 onto the image sensor 600. The contrast control module 870 is connected to a sensor control module 820, which in turn is connected to the monitoring system 230.

[0074] According to the invention, an electrostatic booster lens 112 can now be integrated into the multi-beam particle beam system 1 described above by way of example. The electrostatic booster lens 112 is arranged in the primary particle-optical beam path 11 in the crossover region 108 of the charged first single particle beams 3. This crossover region 108, in turn, is located in the upper focal plane of the objective lens 102. The controller 800 or one of its modules, for example the primary path control module 830, is configured to use a voltage supply unit (in the Fig. 1 to 3 not explicitly shown) to provide a booster high voltage VB at the electrostatic booster lens 112 such that the charged first single particle beams 3 pass through the crossover region 108 in sections with a significantly increased kinetic energy, so that aberrations due to a Coulomb interaction of the charged first single particle beams 3 within the crossover region 108 are reduced. The position of the electrostatic booster lens 112 is in Fig. 1 schematically by means of the arrow, with details of the electrostatic booster lens 112 itself in Fig. 1 are not explicitly shown. Instead, Fig. 4 schematically shows an electrostatic booster lens 112 and its control as well as its influence on the kinetic energy of the charged particles passing through it:

[0075] In Fig. 4 below, the electrostatic booster lens 112 is shown, which in the example shown is essentially designed as a single lens. The single lens comprises a first (upper) electrode 112a, a second (middle) electrode 112b, and a third (lower) electrode 112c. The electrodes 112a, 112b, and 112c can, for example, be designed as thin plates with a central opening, thus forming tubular lenses or tubular lens sections. The central openings are arranged centrally on the particle-optical axis Z or centrally relative to the first particle-optical beam path 11. The first electrode 112a, the second electrode 112b, and the third electrode 112c can be individually supplied with voltage. In the example shown, the voltage supply is controlled by the primary path control module 830.For this purpose, a voltage VB0 is provided at the first electrode 112a of the electrostatic booster lens 112. In the example shown, the same voltage VB0 is also provided at the third electrode 112c of the electrostatic booster lens 112. In contrast, a high voltage VB is provided at the second electrode 112b. The provided voltage VB0 is, for example, a low voltage. Preferably, the low voltage VB0 can also be 0 V, i.e., ground potential. The booster high voltage VB can, for example, be ≥ 10 kV or ≥ 15 kV. Fig. Figure 4 therefore only shows the principle. Due to the potential difference between the first electrode 112a and the second electrode 112b (and with appropriate polarity), the charged first single-particle beams 3 are accelerated in the region between the electrodes 112a, 112b, and their kinetic energy is greatly increased. Inside the tube lens section, or inside the middle electrode 112b, the charged first single-particle beams 3 then move with the maximum kinetic energy Ekin. maxAfter exiting the middle electrode 112b, the charged particles or the charged first single particle beams 3 are strongly decelerated due to the potential difference between the electrodes 112b and 112c, down to the original kinetic energy EPB0, which the charged particles or particle beams 3 already had upon entering the acceleration field of the electrostatic booster lens 112. This kinetic energy EPB0 can, for example, be identical to the kinetic energy ET, which in Fig. 2 for the primary path. If the electrostatic booster lens 112 is designed exactly as a single lens, the kinetic energy of the charged first single-particle beams 3 upon entering the electrostatic booster lens 112 is the same as upon exiting the electrostatic booster lens 112. As a result, the kinetic energy in the crossover region 108 is significantly increased in sections, and only in sections.

[0076] Fig. 5 shows a slight modification of the Fig. 4: The electrostatic booster lens 112 is not exactly designed as a single lens, but only essentially as a single lens 112. As in the previous example according to Fig. 4, a high voltage or a booster high-voltage potential VB is applied to the second electrode 112b. However, the two low-voltage potentials at the first electrode 112a and the third electrode 112c of the electrostatic booster lens 112 are Fig. 5 are not identical, but slightly different. In the example shown, a low-voltage potential VB1 is applied to the first electrode 112a and a low-voltage potential VB2 is applied to the third electrode 112c. The kinetic energy of the charged particles or charged first single-particle beams 3 is therefore slightly different when entering the electrostatic booster lens 112 than when exiting the electrostatic booster lens 112. Specifically, the kinetic energy when entering Fig. 5 with EPB1 slightly higher than upon exit, whereby the kinetic energy is then only EPB2 with EPB1 > EPB2. However, the maximum kinetic energy inside the middle electrode 112b is identical in both cases. Theoretically, it is also possible that the kinetic energy EPB2 upon exiting the electrostatic booster lens 112 is greater than upon entering the electrostatic booster lens 112, so that EPB2 > EPB1 applies. In this context, it should be noted that in the diagram section in Fig. 5 the kinetic energy is shown only schematically and not to scale.

[0077] Because the kinetic energy of the first individual particle beams 3 is significantly increased specifically in the crossover region 108 and thus only in certain sections, it is not necessary to change the voltage applied to other elements of the multi-beam particle beam system 1 compared to the prior art. In particular, it is not necessary to further increase the magnitude of a high voltage applied to the particle source 301, nor is it necessary to do so with the high voltage provided at the sample stage 500 or by means of the power supply 503 on the sample support plate 505. Instead, the first high voltage V1 provided at the particle source by means of a voltage supply unit can satisfy the following relationship in terms of magnitude: 20 kV ≤ V1 ≤ 40 kV, preferably 25 kV ≤ V1 ≤ 35 kV.Furthermore, the following relationship can apply to the second high voltage V2 provided at the sample: 20 kV ≤ V2 ≤ 40 kV, preferably 25 kV ≤ V2 ≤ 35 kV. Furthermore, it is possible to provide a maximum low voltage Vm at the multi-aperture arrangement 305 or at the multi-beam generator 305 (also called micro-optics), even when implementing a booster lens 112. Preferably, a low voltage Vm can be provided at the multi-aperture arrangement 305, which, in terms of magnitude, satisfies the following relationship: 0 V ≤ Vm ≤ 100 V, preferably 0 V, i.e., ground potential. It is then also possible to apply ground potential or at least only a low-voltage potential to the beam tube arrangement 151.

[0078] In this way, the first single particle beams 3 can reach their maximum kinetic energy Ekin in the area of ​​the booster lens 112 and thus in the crossover area 108. maxin the particle-optical beam path 11 between the particle source 301 and the sample 7, wherein the following relationship applies to a maximum electrical potential increase ΔVB caused by the electrostatic booster lens 112: ΔVB ≥ 10 kV, preferably ΔVB ≥ 15 kV. For example, the high voltage VB at the electrostatic booster lens 112 or at the second (middle) electrode 112b can be VB ≥ 10 kV, preferably VB ≥ 15 kV.

[0079] A length LB of the electrostatic booster lens 112 along the particle-optical axis Z is very short and the following relation can apply, for example: 2 mm ≤ LB ≤ 10 mm. The length LB is in Fig. 4 and Fig. 5 and is identical to the length in the direction of the particle-optical beam path 11 in the primary path, in which the electrostatic booster lens 112 is effective overall. The length LB here essentially corresponds to the distance between the electrodes or counterelectrodes of the electrostatic booster lens. Furthermore, according to an example, the following relationship applies for a length LBm of the middle electrode 112b: 1.5 mm ≤ LBm ≤ 4.5 mm.

[0080] Fig. Figure 6 schematically shows an arrangement of an electrostatic booster lens 112 in a multi-beam particle beam system 1, for example in an inspection system or in a lithography system. As already described in connection with Fig. As explained in Figure 1, the collective scan deflector 110, which serves to scan the sample 7, is also arranged near the crossover region 108. This collective scan deflector 110 comprises an upper scan deflector 110a and a lower scan deflector 110b. Between this upper scan deflector 110a and the lower scan deflector 110b, the electrostatic booster lens 112 or its second (middle) electrode 112b is arranged. Both the upper scan deflector 110a, the lower scan deflector 110b and the middle electrode 112b of the booster lens 112 are located within a beam tube interruption: In the Fig. In the embodiment illustrated in Figure 6, the jet pipe 151 is divided into a first (upper) jet pipe section 151.1 and a second (lower) jet pipe section 151.2. A DC voltage VT1 is applied to the first (upper) jet pipe section 151.1. A DC voltage VT2 is applied to the second (lower) jet pipe section 151.2. The provision of the DC voltages VT1 and VT2 is controlled by the primary path control module 830. The voltages VT1 and VT2 can be different, but they can also be identical. Together with the electrode 112b of the electrostatic booster lens 112, to which a high voltage or high-voltage potential VB is applied, the electrostatic booster lens 112 as a whole is thus essentially formed as a single lens. In other words, the exit region 154 of the first jet pipe section 151.1, the first electrode 112a of the electrostatic booster lens 112 is realized, and the third electrode 112c of the electrostatic booster lens 112 is realized by the entry region 155 into the second beam tube section 151.2.

[0081] According to an alternative embodiment, it would also be possible for one of the scan deflectors 110a, 110b to be subjected to an offset voltage VB (not shown). Then, the other of the scan deflectors 110b, 110a and one of the beam tube sections 154, 155 can form the counter electrodes of the booster lens 112. Generally speaking, at least one of the electrodes 112a, 112b, 112c of the electrostatic booster lens 112 can be realized by means of an offset potential at a multipole electrode, for example, at one of the scan deflectors 110a, 110b.

[0082] While the electrostatic booster lens 112 and the voltages VT1, VB, and VT2 applied thereto are provided or controlled by the primary path control module 830, the voltage provided to the collective beam deflector 110 is provided or controlled by the scan deflector control module 860. In the example shown, the upper scan deflector 110a is designed as an electrostatic octupole electrode, wherein the octupole electrode is supplied with the voltage V8a. Each of the eight electrodes of the octupole can be individually supplied with a voltage. The same applies to the lower scan deflector 110b, which is designed as an electrical octupole electrode, wherein an individually adjustable voltage can be applied to each of the eight electrodes; this is symbolically represented by the voltage V8b in Fig. 6 shown.

[0083] Fig. Figure 7 shows schematically an electrostatic booster lens 112 and its control as well as its influence on the kinetic energy of the charged particles flying through it in an arrangement of the booster lens 112 according to Fig. 6. The electrostatic booster lens 112 comprises, as its first electrode, the beam tube exit region 154 of the first (upper) beam tube section 151.1 and, as its third electrode, the beam tube entry region 155 of the second (lower) beam tube section 151.2. The second electrode, i.e., the middle electrode 112b of the electrostatic booster lens 112, is provided centrally. In this way, a single lens is formed, at whose electrodes the voltages VT1, VB, and VT2 are applied. The voltage VB is a high-voltage potential. The applied voltages VT1, VB, and VT2, which are provided by the primary path control module 830, are static voltages. In contrast, the upper scan deflector 110a and the lower scan deflector 110b of the collective scan deflector 110 are dynamically controlled.The specific control of the multipole electrodes, for example, the octupole electrodes, depends on the scanning position of the first single particle beams 3 on the sample. Therefore, it is also advisable to control the collective scan deflector 110 using a separate module, in the example shown using the scan deflector control module 860.

[0084] As already mentioned, the voltage applied to the center electrode 112b of the electrostatic booster lens 112 is a high voltage. In contrast, the voltages applied to the multipole electrodes 110a, 110b of the collective scanning deflector 110 are low voltages. They are, for example, approximately 50V.

[0085] The control of the five electrodes in Fig. 7 is also reflected in the corresponding diagram of the kinetic energy of the charged particles forming the charged first single particle beams 3: In the diagram in Fig. Figure 7 shows the kinetic energy for two different activations of the upper scan deflector 110a and the lower scan deflector 110b. The solid line A1 shows the kinetic energy profile during a first activation of the collective scan deflector 110, and the dashed line A2 shows the kinetic energy profile during a second activation of the collective scan deflector 110. During the first activation A1, the kinetic energy of the charged particles in the area between the first electrode 112a of the booster lens 112 and the upper scan deflector 110a is slightly reduced, thus slightly decelerating the particles. After passing through the upper scan deflector 110a, a strong, boosted increase in kinetic energy occurs until it enters the middle electrode 112b of the electrostatic booster lens 112. The middle electrode 112b is then charged with the maximum kinetic energy Ekin maxor the kinetic energy EPB. A drastic reduction in kinetic energy then occurs between the middle electrode 112b of the electrostatic booster lens 112 and the lower scan deflector 110b. Between exiting the lower scan deflector 110b and entering the beam tube entry area 155 or the third electrode 112c of the electrostatic booster lens 112, a further slight reduction in kinetic energy occurs.

[0086] In the second illustrated control of the collective scan deflector 110, there is initially a slight increase in the kinetic energy between the first electrode 112a or the beam tube exit area 154, before the strong increase in speed or the maximum kinetic energy Ekin maxis reached. This maximum kinetic energy is essentially identical to the kinetic energy during the second activation of the collective scan deflector 110 when the collective scan deflector is activated in the first activation mode A1. The kinetic energy then drops significantly, specifically to a somewhat lower level in the second activation mode A2 than in the first activation mode A1 of the collective scan deflector 110. A further, slight reduction in kinetic energy then occurs between the lower scan deflector 110b and the beam tube inlet region 155, which serves as the third electrode 112c of the electrostatic booster lens 112. Despite the slight potential differences or the differences in the kinetic energy upon entering and exiting the electrostatic booster lens 112, the electrostatic booster lens is also Fig. The example shown in Figure 7 is essentially designed as a single lens.

[0087] Fig. Fig. 8 schematically shows a further arrangement of an electrostatic booster lens 112 in a multi-beam particle beam system 1. The multi-beam particle beam system can be, for example, an inspection system or a lithography system. Fig. In the example shown in Figure 8, the lens effect of the electrostatic booster lens 112 is at least partially realized by means of an offset voltage at a multipole electrode. Specifically, in the example shown in Fig. In the embodiment shown in Figure 8, the collective beam deflector is combined with the counter electrodes (i.e., the first and third electrodes of the electrostatic booster lens 112): With a multipole electrode, all individual electrodes can, in principle, be controlled individually. This is correspondingly the case with the upper scan deflector 110a and the lower scan deflector 110b. Additionally, it is possible to apply the same voltage as an offset to all individual electrodes of the multipole electrode. This gives the multipole electrode a round lens component, and a round lens effect can be achieved in addition to the collective beam deflection.

[0088] In the example shown, the multi-beam particle beam system 1 comprises a beam tube assembly 151, which in the example shown has a beam tube extension, i.e., a section that extends into the objective lens 102. The electrostatic booster lens 112 is arranged within this beam tube extension. In this example, no beam tube interruption is provided in the region of the crossover area 108.

[0089] A booster high voltage VB, which is provided statically, is applied to the middle electrode 112b of the electrostatic booster lens 112. The voltage V8a already provided at the upper scan deflector 110a is provided dynamically and superimposed with a static offset. Accordingly, the voltage V8b at the lower scan deflector 110b is also provided dynamically and superimposed with a static offset voltage. The two offset voltages can be identical, but they can also be different from each other.

[0090] Fig. Figure 9 schematically shows a 4f system with an electrostatic booster lens 112 in a crossover region 108 and its influence on the particle-optical beam path. A 4f system is a schematic representation of an imaging system. Basically, the 4f system comprises a first lens with a focal length f1 and a second lens with a focal length f2. The magnification of the system is M = f2 : f1. The intermediate image plane between the two subsystems is the plane in which the principal rays of the individual particle beams move parallel to each other (this is shown in Fig. 9 cannot be seen in this way with the simplified representation). If an aperture is arranged in the intermediate image plane in the crossover region 108, or more precisely in the crossover plane 108, the telecentric properties of the imaging system are not changed.

[0091] Applied to the multi-beam particle beam system 1, this means the following: For inspection purposes or illumination purposes with high uniformity, the first individual particle beams 3 must be telecentric upon impingement in the object plane 101. The second lens in the 4f system therefore corresponds to the objective lens 102. The upper focal plane of the objective lens 102 must therefore coincide with the crossover region 108 for telecentric imaging. The electrostatic booster lens 112 must therefore be located in the upper focal plane of the objective lens 102 or, in other words, in the crossover region 108. As long as the electrostatic booster lens 112, or in a single-lens configuration, its central electrode 112b, is located within the crossover region 108, the provision of the electrostatic booster lens 112 does not change the telecentric properties of the first individual particle beams 3 upon impingement in the object plane 101.

[0092] In the Fig. In the example shown in Figure 9, the intermediate image plane 321 and a field lens 103 are also shown. In the example shown, the first individual particle beams 3 are parallel to each other in the intermediate image plane 321. However, this does not have to be the case.

[0093] If the excitation of the electrostatic booster lens 112 is now varied, a working distance WD or the position of the object plane 101 relative to the position of the object plane 101' changes. For this variation of the electrostatic booster lens 112, a first adjustment means can be provided, which is controlled by the controller 800, so that the booster high voltage VB applied to the electrostatic booster lens 112 is changed. Additionally or alternatively, this changed setting of the electrostatic booster lens 112 can also change the numerical aperture NA of the first individual particle beams 3 upon impact in the object plane 101, 101'.

[0094] According to one embodiment of the invention, a second adjustment means is further provided, which is different from the first adjustment means. The controller 800 is then configured to control the second adjustment means so that the changed working distance WD of the first individual particle beams 3 is corrected or changed and / or so that the changed numerical aperture NA of the first individual particle beams 3 upon impingement in the object plane 101 is corrected or changed. Generally speaking, the multi-beam particle beam system 1 comprises a further degree of freedom with a variable static booster high voltage VB applied to the electrostatic booster lens 112. As a result, changes in other imaging parameters caused by varying the refractive power of the electrostatic booster lens 112 can be corrected accordingly.However, as long as the electrostatic booster lens 112 is essentially located within the crossover region 108, neither the magnification nor the telecentricity changes, even if the control of the electrostatic booster lens 112 is changed. The 4f system according to . Fig. 9 remains geometrically unchanged in principle.

[0095] In order to keep the entire system telecentric, according to a preferred embodiment of the invention, both the objective lens focal length f2 and the field lens focal length f1 can be varied simultaneously. The effect on the image scale is very small and can be tolerated. Even if the aperture plane shifts slightly in the area of ​​the electrostatic booster lens 112, the crossover area still remains within the electrostatic booster lens 112. The changed position of the object plane 101 is Fig. 9 indicated by the dashed beam path.

[0096] A change in the refractive power of the objective lens 102 can be realized in various ways: According to a first embodiment, the excitation or a current I of the objective lens can be varied (cf. Fig. 2). Additionally or alternatively, a variation in the refractive power of the objective lens 101 can be effected by changing the control of the collective scanning deflector 110 or at least one of its deflectors 110a, 110b. Additionally or alternatively, if the beam tube arrangement 151 is subdivided into a first (upper) beam tube section 151.1 and a second (lower) beam tube section 151.2, a changed voltage, in particular a changed low voltage VT2, can be applied to the second (lower) beam tube section 151.2. The second, lower beam tube section 151.2 is located within the magnetic field of the objective lens 102, so that a changed voltage at the lower beam tube section 151.2 results in a changed velocity of the charged particles of the first single-particle beams 3 within the magnetic field of the objective lens 102, which in turn changes the refractive power of the objective lens 102.

[0097] Additionally or alternatively, it is possible to arrange an electrostatic correction element in the magnetic field of the objective lens 101.

[0098] The described variation possibilities for the changed refractive power of the objective lens 101 can be realized by means of a second adjustment means (not shown) which is controlled by means of the controller 800 or a component of the controller 800.

[0099] According to an alternative embodiment of the invention, the refractive power of the objective lens 101 remains unchanged and only the refractive power of the field lens 103 is adjusted. As a result, the input telecentricity of the charged first single-particle beams 3.1, 3.2, 3.3 changes in the intermediate image plane 321 and thus upon entry into the 4f system according to Fig. 9. Using a second field lens 333 (see Fig. 1) or an alternative telecentricity adjustment device, the input telecentricity can be changed or adjusted. Overall, the 4f system remains telecentric even in this embodiment, or the first individual particle beams 3 impinge telecentrically on the object plane 101.

[0100] In both embodiments described in more detail above, the extraction field between the electrode 133 and the sample or the wafer 7 can remain unchanged.

[0101] Fig. 10 schematically shows a flowchart of a method according to the invention for operating a multi-beam particle beam system 1, as described above in several embodiments. According to a first method step S1, a multi-beam particle beam system 1 is provided with a crossover region 108 of charged first individual particle beams 3 in the illumination path 11 in an upper focal plane of an objective lens 101.

[0102] In a second method step S2, the kinetic energy of the first single particle beams 3 in the crossing region 108 is increased in sections to significantly reduce the Coulomb interaction between the charged first single particle beams 3.

[0103] According to a method step S3, the maximum kinetic energy of the first individual particle beams 3 is changed in the crossover region, whereby at least one imaging parameter of the multi-beam particle beam system 1 is changed upon impact of the first individual particle beams 3 in the object plane 1. This can be, for example, the working distance WD or the refractive power of the objective lens 101; additionally or alternatively, it can also be the numerical aperture NA. Despite the change in the maximum kinetic energy of the first individual particle beams 3 in the crossover region 108, other imaging parameters do not change, or at least not significantly; in particular, the telecentricity upon impact of the first individual particle beams in the object plane 101 is maintained.

[0104] According to a further method step S4, the correction of at least one changed imaging parameter, for example the changed working distance WD and / or the changed numerical aperture NA, takes place.

[0105] The described method steps of the method according to the invention can be realized with the above-described features of the multi-beam particle beam system 1 and in particular with its particle-optical elements such as the electrostatic booster lens 112 and the described controller 800.

[0106] The embodiments described in the figures are not to be understood as limiting the invention, but merely serve to improve the understanding of the invention.

[0107] A multi-beam particle beam system 1 with improved resolution and higher acquisition speed is disclosed. For this purpose, an electrostatic booster lens 112 is arranged in an upper focal plane of the objective lens 101 at the level of the crossover region 108 of the primary particle beams 3. By means of the electrostatic booster lens 112, the kinetic energy of the primary beams 3 is specifically increased in the crossover region 108, thus reducing the Coulomb interaction between the charged particles 3. List of reference symbols 1 multi-beam particle beam system 3 primary particle beams (first single particle beams) 5 beam spots, impact points of the first single particle beams 7 Object, sample 9 secondary particle beams (second single particle beams) 13 secondary particle-optical beam path 15 beam spots, impact points of the second single particle beams 25 Surface of the object or sample 67 first material composition 69 second material composition 100 object lighting units 101 Object level 102 objective lens 103 Field lens 108 Crossover area 110 collective scan deflector (primary path) 110a upper scan deflector 110b lower scan deflector 112 electrostatic booster lens 112a first electrode of the electrostatic booster lens 112b second electrode of the electrostatic booster lens 112c third electrode of the electrostatic booster lens 133 Electrode 135 first electric field 137 second electric field 151 jet pipe 151.1 first (upper) jet pipe section 151.2 second (lower) jet pipe section 153 jet outlet opening 154 Jet pipe outlet area 155 Jet pipe inlet area 161 winding 163 Pole shoe 165 lower pole shoe segment 200 detection units 222 second collective beam deflector (secondary path) 225 Image plane for second single-particle beams 230 monitoring system 232 high-resolution sensor 235 imaging lens 237 beam splitter mirrors 300 beam generating device 301 particle source 303 Collimating lens system, condenser lens system 304 filter plate 305 Multi-beam generator, multi-aperture arrangement 306 multi-aperture plates 309 primary particle beam 321 Intermediate image plane 331 first field lens 333 second field lens 400 beam switch 500 sample table 503 Sample voltage supply 505 Sample plate 600 image sensor 602 Electron-to-photon converter, scintillator plate 605 convex lens 609 Light beam 611 zoom lens 613 Light entry surface 615 fiber optic 617 Engine, rotary engine 623 Detection element 630 Direction of movement 800 Control 810 Image Control Module 820 Sensor Control Module 830 Primary Path Control Module 840 Secondary Path Control Module 850 Sample Table Control Module 860 Scan deflector control module 870 Contrast Control Module 880 processor for control 890 memory IX User Interface QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 7 244 949 B2

[0004] US 2019 / 0355544 A1

[0004] WO 2021 / 018332 A1 [0037, 0058] US 2019 / 0259575 A1

[0060] US 10 741 355 B1

[0060] WO 2020 151 904 A2

[0067] US 9 536 702 B2 [0067, 0069] EP 2022 / 061042

[0068] DE 10 2022114923.4

[0068]

Claims

[1] Multi-beam particle beam system having the following features: a particle source for emitting a charged particle beam, a multi-aperture arrangement comprising at least one multi-aperture plate having a plurality of through-openings, wherein the multi-aperture arrangement is configured to generate a first field of a plurality of charged first single-particle beams from the charged particle beam; a first particle optics with a first particle optical beam path, which is configured to image the generated first single particle beams onto a sample surface in the object plane, so that the first single particle beams strike the sample surface at impact locations that form a second field; a magnetic and / or electrostatic objective lens through which the first single particle beams pass a sample stage for arranging a sample with a sample surface in the object plane; an electrostatic booster lens, wherein the first particle-optical beam path has a crossover region of the charged first single-particle beams, which crossover region is arranged in the region of an upper focal plane of the objective lens, and wherein the electrostatic booster lens is arranged in the region of this crossover region; a voltage supply unit; and a controller for controlling the multi-beam particle beam system, wherein the controller is configured to provide a booster high voltage VB by means of the voltage supply unit at the electrostatic booster lens such that the charged first single-particle beams pass through the crossover region in sections with a significantly increased kinetic energy, so that aberrations due to a Coulomb interaction of the single-particle beams within the crossover region are reduced. [2] Multi-beam particle beam system according to claim 1, wherein the first individual particle beams in the region of the booster lens and thus in the crossover region have their maximum kinetic energy in the particle-optical beam path between the particle source and the sample; and where the following relation applies to the maximum electrical potential increase ΔVB caused by the booster lens: ΔVB ≥ 10kV, in particular ΔVB ≥ 15kV. [3] Multi-beam particle beam system according to one of the preceding claims, wherein the controller is configured to provide a first high voltage V1 to the particle source by means of the voltage supply unit, wherein the controller is configured to provide a maximum of a low voltage Um to the multi-aperture arrangement by means of the voltage supply unit, and wherein the controller is configured to provide a second high voltage V2 on the sample table and thus on the sample by means of the voltage supply unit. [4] Multi-beam particle beam system according to the preceding claim, where the first high voltage V1 and the second high voltage V2 have the same sign; and wherein the first high voltage V1 at the particle source satisfies the following relation: 20kV ≤ V1 ≤ 40kV, in particular 25kV ≤ V1 ≤ 35kV; and wherein the second high voltage V2 on the sample table satisfies the following relation: 20kV ≤ V2 ≤ 40kV, in particular 25kV ≤ V2 ≤ 35kV; and where the low voltage Um at the multi-aperture arrangement satisfies the following relation in terms of magnitude: 0V ≤ Vm ≤ 100V, in particular 0V. [5] Multi-beam particle beam system according to the preceding claim, wherein the booster high voltage VB has a different calibration than the first and second high voltages, and where the booster high voltage UB at the electrostatic booster lens satisfies the following relation in terms of magnitude: VB ≥ 10kV, in particular VB ≥ 15kV. [6] Multi-beam particle beam system according to one of the preceding claims, where the following relation applies to a length LB of the electrostatic booster lens along the particle-optical axis Z: 2mm ≤ LB ≤ 10mm; and / or where for a length LBm of a central electrode of the electrostatic booster lens the following relation applies: 1.5mm ≤ LBm ≤ 4.5 mm. [7] Multi-beam particle beam system according to one of the preceding claims, wherein the electrostatic booster lens is functionally designed essentially as a single lens. [8] Multi-beam particle beam system according to one of the preceding claims, wherein the lens effect of the electrostatic booster lens is realized at least partially by means of an offset voltage at a multipole electrode. [9] Multi-beam particle beam system according to one of the preceding claims, wherein the multi-beam particle beam system comprises a beam tube arrangement within which at least the first individual particle beams are guided at least in sections, and wherein the beam tube assembly has a beam tube extension extending into the objective lens, and wherein the electrostatic booster lens is arranged within this beamline extension. [10] Multi-beam particle beam system according to one of claims 1 to 8, wherein the multi-beam particle beam system comprises a beam tube arrangement within which at least the first individual particle beams are guided at least in sections, and wherein the jet pipe arrangement has a jet pipe interruption in the region of the crossing area and the jet pipe arrangement is thereby subdivided into a first jet pipe section and a second jet pipe section, and wherein a first upper electrode of the electrostatic booster lens is formed by means of the first beam tube section, to which a maximum low voltage VT1 is applied, wherein a second central electrode of the electrostatic booster lens is arranged within the beam tube interruption, at which the booster high voltage VB is provided, and wherein a third lower electrode of the electrostatic booster lens is formed by means of the second beam tube section, to which a maximum low voltage VT2 is applied. [11] Multi-beam particle beam system according to one of the preceding claims, wherein the multi-beam particle beam system comprises a collective scanning deflector with an upper deflection unit in the upper crossover region and with a lower deflection unit in the lower crossover region, and wherein the middle electrode of the electrostatic booster lens is arranged between the upper deflection unit and the lower deflection unit. [12] Multi-beam particle beam system according to one of the preceding claims, wherein the multi-beam particle beam system further comprises a first adjusting means, and wherein the controller is configured to control the first adjustment means so that the booster high voltage VB applied to the electrostatic booster lens is changed, which in turn changes a working distance WD of the first individual particle beams and / or a numerical aperture NA of the first individual particle beams upon impact in the object plane. [13] Multi-beam particle beam system according to claim 12, which further comprises a second adjusting means different from the first adjusting means; and wherein the controller is configured to control the second adjustment means so that the changed working distance WD of the first individual particle beams is corrected and / or so that the changed numerical aperture NA of the first individual particle beams is corrected upon impact in the object plane. [14] A multi-beam particle beam system according to claim 13, wherein the second adjusting means is configured to effect a changed excitation of the objective lens and / or a field lens. [15] A multi-beam particle beam system according to claims 11 and 13, wherein the second adjusting means is configured to effect a changed control of the collective scanning deflector. [16] A multi-beam particle beam system according to claims 10 and 13, wherein the second adjusting means is configured to apply a varied voltage VT2 to the second beam tube section. [17] A multi-beam particle beam system according to claim 13, wherein the second adjusting means comprises an electrostatic correction element arranged in a / the magnetic field of the objective lens. [18] A multi-beam particle beam system according to claim 13, wherein the multi-beam particle beam system comprises a multipole corrector and wherein the second adjusting means is configured to effect a changed control of the multipole corrector. [19] Multi-beam particle beam system according to one of the preceding claims, wherein the multi-beam particle beam system further comprises an intermediate image plane and a telecentricity correction means, in particular an additional field lens, in the first particle-optical beam path, wherein the telecentricity correction means is arranged between the multi-beam generator and the intermediate image plane, and wherein the controller is configured to control the telecentricity correction means so that an input telecentricity of the first single particle beams in the intermediate image plane is varied. [20] A multi-beam particle beam system according to any preceding claim, configured for telecentric impingement of the first single particle beams in the object plane. [21] Multi-beam particle beam system according to one of the preceding claims, further comprising a detection system having a plurality of detection areas forming a third field; a second particle optics with a second particle-optical beam path, which is configured to image second single-particle beams emanating from the impact locations in the second field onto the third field of the detection areas of the detection system; and a beam switch arranged in the first particle-optical beam path between the multi-aperture arrangement and the objective lens, and arranged in the second particle-optical beam path between the objective lens and the detection system, and whereby the second single particle beams also pass through the objective lens. [22] Method for operating a multi-beam particle beam system, in particular a multi-beam particle beam system according to one of the preceding claims, comprising the following steps: (a) providing a multi-beam particle beam system having a crossover region of charged first single particle beams in the illumination path in an upper focal plane of an objective lens; and (b) Sectionally, significantly increasing the kinetic energy of the first single-particle beams in the crossover region to significantly reduce the Coulomb interaction between the charged first single-particle beams. [23] A method according to the preceding claim, further comprising the following steps: (c) changing the maximum kinetic energy of the first single-particle beams in the crossover region, whereby at least one imaging parameter of the multi-beam particle beam system is changed upon impingement of the first single-particle beams in an object plane; and (d) correcting the at least one changed imaging parameter. [24] Computer program product comprising a program code for carrying out the method according to one of claims 22 to 23.

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