Multi-particle beam system with contrast correction lens system

Abstract

A multi-particle beam system (1) comprising the following: a multi-beam particle source (21) configured to generate a first field of a plurality of charged first particle beams (3); a first particle optic (80) with a first particle-optical beam path configured to map the generated single-particle beams (3) onto an object plane (101) such that the first particle beams (3) meet at points of impact on an object (7) forming a second field; a detection system (13) with a plurality of detection areas forming a third field; a second particle optics (90) with a second particle-optical beam path configured to map second single-particle beams (9) originating from the points of impact in the second field onto the third field of the detection areas of the detection system (13) (102); a magnetic objective lens (102), in particular a magnetic immersion lens, through which both the first (3) and the second single-particle beams (9) pass; a beam splitter (400) arranged in the first particle-optical beam path between the multi-beam particle source (21) and the objective lens (102), and arranged in the second particle-optical beam path between the objective lens (102) and the detection system (13); and a controller (10); wherein in the second particle-optical beam path between the beam switch (400) and the detection system (13) a beam crossing (510) of the second single-particle beams (9) takes place, wherein in the area of ​​beam crossing (510) a contrast aperture (511) with a central recess for filtering the second single-particle beams (9) according to their starting angles from the object plane (101) is arranged, wherein in the second particle-optical beam path between the objective lens (102) and the contrast aperture (511) a contrast-correction lens system (500) with a first magnetic contrast-correction lens (500) is arranged, which is configured to generate a magnetic field of adjustable strength and to correct beam tilts of the second single-particle beams (9) in the beam crossing (510) with respect to the optical axis (Z) of the multi-particle beam system (1), and wherein the control (10) is configured to control the excitation of the contrast correction lens system (500).

Description

Field of invention

[0001] The invention relates to particle beam systems that operate with a multitude of particle beams. State of the art

[0002] Multi-beam particle microscopes, like single-beam particle microscopes, can be used to analyze objects on a microscopic scale. For example, these particle microscopes can capture images of an object that represent its surface. In this way, the surface structure can be analyzed. While a single-beam particle microscope uses a single beam of charged particles, such as electrons, positrons, muons, or ions, to analyze the object, a multi-beam particle microscope uses multiple beams. These multiple beams, also called beams, are directed simultaneously at the object's surface, allowing a significantly larger area of ​​the object's surface to be scanned and analyzed in the same amount of time compared to a single-beam particle microscope.

[0003] From WO 2005 / 024 881 A2, a multi-particle beam system in the form of an electron microscopy system is known, which operates with a multitude of electron beams to scan an object under investigation with a parallel beam of electron beams. The beam of electron beams is generated by directing an electron beam produced by an electron source onto a multi-aperture plate, which has a multitude of openings. Part of the electrons of the electron beam strikes the multi-aperture plate and is absorbed there, while another part of the beam passes through the openings of the multi-aperture plate, so that an electron beam is formed in the beam path behind each opening, the cross-section of which is defined by the cross-section of the opening.Furthermore, appropriately selected electric fields, provided in the beam path before and / or after the multi-aperture plate, cause each aperture in the plate to act as a lens on the electron beam passing through it. This focuses the electron beams into a plane located at a distance from the multi-aperture plate. The plane in which the electron beam foci are formed is then imaged onto the surface of the object under investigation by a subsequent optical system, so that the individual electron beams, as primary beams, strike the object. There, they generate interaction products emanating from the object, such as backscattered electrons or secondary electrons, which are shaped into secondary beams and directed by a further optical system onto a detector.There, each of the secondary beams strikes a separate detector element, so that the electron intensities detected by this element provide information about the object at the location where the corresponding primary beam strikes the object. The bundle of primary beams is systematically scanned across the surface of the object to generate an electron microscopic image of the object in the manner typical for scanning electron microscopes.

[0004] Magnetic immersion lenses are frequently used as objective lenses in the above-mentioned multi-particle beam systems. In this system, the object plane is located within the magnetic field of the objective lens. Secondary beams originating from a given point of impact on the object therefore traverse an asymmetric magnetic field, which leads to an undesired tilting of the particle beam in the subsequent particle-optical beam path. This tilting causes precision problems in particle-optical imaging at focal planes and also during beam crossings.

[0005] In the area where the beams cross over the object and the detector array, a diaphragm is typically positioned. This diaphragm serves two purposes: firstly, to prevent crosstalk between the secondary beams, and secondly, to ensure good and uniform contrast (edge ​​contrast) across all secondary beams during imaging with the detector array. This, however, requires that all beams passing through the diaphragm strike it centrally with respect to the optical axis. Only then is precise filtering of the secondary beams with respect to their starting angle from the sample / object plane possible. This, in turn, requires that the secondary beams are not tilted relative to each other. The degree of this tilt depends on the position of a secondary beam within the array of secondary beams. Beams located further out in the array exhibit greater tilt.

[0006] WO 2019 / 243 349 A2 discloses a multi-particle beam system that incorporates a deflector array in the secondary path in the region of an intermediate image plane. This allows individual tilted secondary beams to be selectively deflected and their propagation direction corrected. However, this solution requires extremely high precision in the fabrication and arrangement of numerous components of the deflector array relative to one another, and it also necessitates complex control of the individual components.

[0007] US 9,153,413 B2 discloses a multi-beam particle microscope with a beam splitter that is achromatic with respect to primary particle beams, but dispersive with respect to secondary particle beams. The secondary particle beams then pass through a magnetic lens, which projects different virtual images, correlated with different energies of the secondary particle beams, onto underdetection units. The lens allows for imaging and magnification of the energy distribution of the secondary particle beams.

[0008] US 2015 / 0287568 A1 discloses a multi-beam particle microscope and a method for adjusting an autofocus. Astigmatic particle beams are generated in an outer area of ​​the beam bundle, and the changes in these beam parameters when the focus is changed are analyzed and used to improve the focusing of stigmatic particle beams. Description of the invention

[0009] The object of the present invention is therefore to provide an alternative multi-particle beam system that enables improved contrast and / or resolution. In particular, this contrast improvement should be achievable uniformly for all beams, even with a small contrast aperture and when using a large number of individual particle beams. Furthermore, the contrast improvement of the multi-particle beam system should also be achievable for planar samples such as semiconductor wafers, which exhibit practically no topographic contrast.

[0010] Another objective of the invention is to optionally adjust telecentric illumination at the detector.

[0011] Another function of the invention is to illuminate a sample telecentrically.

[0012] The first problem is solved by the independent patent claim. Preferred embodiments of the invention are described in the dependent patent claims.

[0013] According to a first aspect of the invention, it relates to a plurality particle beam system comprising the following: a multi-beam particle source configured to generate a first field of a multitude of charged first particle beams; a first particle optics with a first particle-optical beam path configured to map the generated single-particle beams onto an object plane, such that the first particle beams hit an object at points of impact that form a second field; a detection system with a plurality of detection areas forming a third field; a second particle optics system with a second particle-optical beam path configured to image second single-particle beams emanating from the points of impact in the second field onto the third field of detection areas of the detection system; a magnetic objective lens, in particular a magnetic immersion lens, through which both the first and the second single-particle beams pass; a beam divider arranged in the first particle-optical beam path between the multi-beam particle source and the objective lens, and arranged in the second particle-optical beam path between the objective lens and the detection system; and a control system; wherein in the second particle-optical beam path between the beam switch and the detection system a beam crossing of the second single-particle beams takes place, wherein in the area of ​​the beam crossing a contrast aperture with a central recess for filtering the second single-particle beams according to their starting angles from the object plane is arranged, wherein in the second particle-optical beam path between the objective lens and the contrast aperture a contrast-correction lens system with a first magnetic contrast-correction lens is arranged, which is configured to generate a magnetic field of adjustable strength and to correct beam tilts of the second single-particle beams in the beam crossing with respect to the optical axis of the multi-particle beam system, and the control is configured to control the excitation of the contrast correction lens system.

[0014] The charged particles can be, for example, electrons, positrons, muons, ions, or other charged particles. Preferably, these are electrons, which are generated, for example, using a thermal field emission source (TFE). However, other particle sources can also be used.

[0015] The number of initial single-particle beams is variably selectable. However, it is advantageous if the number of particle beams is 3n (n-1) + 1, where n is any natural number. This allows for a hexagonal grid arrangement of the detection areas. Other grid arrangements of the detection areas, e.g., in a square or rectangular grid, are also possible. For example, the number of initial single-particle beams can be more than 5, more than 60, or more than 100.

[0016] According to the invention, in the second particle-optical beam path between the beam splitter and the detection system, a beam crossing of the second individual particle beams is provided. A contrast aperture with a central recess is arranged in the region of the beam crossing. Ideally, the second individual particle beams lie exactly on top of each other in the region of the beam crossing. This makes it possible to select the contrast aperture with its central recess such that a large proportion of the beam intensity of each second individual particle beam is retained even when clipped by the contrast aperture. This applies particularly to second individual particle beams originating further away from the optical axis, which are especially affected by the tilting of the second individual particle beams when a magnetic immersion lens is used as the objective lens.Typically, weak immersion lenses only exhibit a remanent azimuthal or tangential tilt of a single-particle beam of a few degrees, e.g., about 2° or 5°. However, strong immersion lenses can exhibit significantly stronger remanent azimuthal or tangential tilts, e.g., of about 30°, 40°, 50°, or even more. An azimuthal or tangential tilt of a single-particle beam refers to a tilt or directional component of a single-particle beam that is perpendicular to an optical axis and perpendicular to a radial direction of the beam. The terms azimuthal and tangential are synonymous, with a tangential directional component being a component that is tangential to a circumferential direction around an orbit perpendicular to the optical axis.The azimuthal or tangential tilt is also referred to here, for simplicity, as Larmor rotation, where Larmor rotation generally encompasses both a pure rotation of a grid arrangement of the individual particle beams and the azimuthal or tangential tilt of the individual particle beam. The term velocity component is used equivalently for the directional component.

[0017] The contrast correction lens system according to the invention compensates precisely for this remanent azimuthal or tangential tilt. The contrast correction lens system comprises at least one first magnetic contrast correction lens, but it can also include a second, third, fourth, or more magnetic contrast correction lenses. These lenses can be identical or different in design. The tilt of the second beam of individual particles is caused by the Lorentz force or the Larmor rotation of the charged particles in the magnetic field. Accordingly, this tilt is compensated for precisely by a further magnetic field of adjustable strength, as described in the invention. This is a precision correction. The magnetic field of the magnetic contrast correction lens(es) is therefore relatively weak and preferably extends over a relatively long area along the optical axis in order to perform the correction.In the magnetic field of the contrast-correcting lens(es), the second beams of individual particles move along a spiral path. Preferably, it is designed such that less than one full rotation within the magnetic field is required for correction.

[0018] The multi-particle beam system includes a controller configured to manage the excitation of the contrast-correcting lens system. This controller can be a single unit that manages the entire multi-particle beam system and its components. Alternatively, a separate controller can be provided for the contrast-correcting lens(es).

[0019] Preferably, the contrast-correcting lens system is arranged at a location or locations in the second particle-optical beam path where no other magnetic lens fields are present. This facilitates precise adjustment of the Larmor rotation compensation.

[0020] The term magnetic contrast correction lens encompasses not only the fact that it is a magnetic particle lens, but also its function of correcting contrast. A contrast correction lens must therefore be suitable and designed for this purpose.

[0021] According to a preferred embodiment of the invention, the first magnetic contrast correction lens is arranged in an area where, during operation of the multiple particle beam system, the second single particle beams converge or divergently.

[0022] According to a preferred embodiment of the invention, the excitation of the contrast-correcting lens system is controlled such that, after passing through the contrast-correcting lens system, the second single-particle beams in a subsequent image plane or intermediate image plane of the second particle-optical beam path run essentially parallel to the optical axis and, in the subsequent beam path outside of magnetic lenses, exhibit essentially no different azimuthal velocity components. The second single-particle beams can strike the detection system telecentrically. However, additional correctors may be required to fulfill this telecentricity requirement.

[0023] According to a preferred embodiment of the invention, the excitation of the contrast-correcting lens system is controlled such that, after passing through the contrast-correcting lens system, all second individual particle beams lie essentially one above the other in a subsequent beam crossing of the second particle-optical beam path and pass through the beam crossing centrally with respect to the optical axis of the system. In the subsequent beam path outside of magnetic lenses, the second individual particle beams exhibit essentially no different azimuthal velocity components. The azimuthal velocity components can, in particular, be zero. This is a prerequisite for ensuring that, in a beam crossing, all second individual particle beams lie exactly one above the other and that a uniform, high imaging contrast is achieved across all second individual particle beams.In this context, one speaks of the homocentricity of the bundle of two single-particle beams, and the center point or central ray of each second single-particle beam lies practically exactly on the optical axis of the system at the beam intersection. The maximum deviation from the central beam axis (heavy ray) is preferably less than 4%, particularly less than 2%, and / or less than 1%, of the radius (recess) of the contrast aperture used. The center point or central ray of each second single-particle beam refers to the ray of each second single-particle beam that is perpendicular to an object plane, in which, for example, the surface of a semiconductor wafer is arranged. The central ray can coincide with a heavy ray of a second single-particle beam.

[0024] According to a preferred embodiment of the invention, the magnetic field of the first contrast-correcting lens is aligned substantially parallel to the optical axis of the system. The magnetic contrast-correcting lens is arranged in a region of the second single-particle beams where the second single-particle beams converge or diverge with respect to their radial propagation direction; that is, the second single-particle beams are not parallel or telecentric to each other. This causes the charged particles to move in a spiral path around the optical axis within the magnetic field. The magnetic field is substantially homogeneous. Second single-particle beams aligned along or parallel to the optical axis are not deflected in the magnetic field of the first contrast-correcting lens because they lack a radial velocity component.However, if the second individual particle beams are inclined to the optical axis and thus also to the magnetic field, the Lorentz force acts on them in the magnetic field, and the contrast-correcting lens system can be used to compensate for the azimuthal velocity component with the aid of the Larmor rotation. In a convergent or divergent bundle of two individual particle beams, the magnitude of a radial directional component of an individual particle beam with respect to an optical axis increases with increasing distance of the individual particle beam from the optical axis. In the axially aligned magnetic field of the contrast-correcting lens(es), a second individual particle beam thus acquires an azimuthal or tangential directional component that is proportional to the radial directional component and counteracts the residual azimuthal or tangential tilt.This compensates for the residual azimuthal or tangential tilting of the individual particle beams.

[0025] According to a preferred embodiment of the invention, the length L of the first contrast correction lens is greater than the radius r of the contrast correction lens, i.e., L > r.

[0026] According to a further preferred embodiment of the invention, the length L of the first contrast correction lens is at least twice the radius r of the contrast correction lens, i.e., L > 2r. The length L of the first contrast correction lens is measured along the optical axis of the system. It corresponds, for example, to the distance between two pole pieces of a magnetic contrast correction lens and / or the length over which the magnetic field is present and effective. The radius r corresponds, for example, to half the aperture width of the pole pieces, which can be, for example, a few centimeters, e.g., about 2 cm or 5 cm.

[0027] According to a preferred embodiment of the invention, the length L of the first contrast correction lens is at least 15 cm, in particular at least 20 cm and / or at least 30 cm. Integrating a contrast correction lens into a multi-particle beam system therefore requires sufficient space. However, a long contrast correction lens has the advantage that a relatively weak magnetic field can be used very precisely for contrast correction. The axial magnetic field can, for example, have a magnetic field strength of about 1 mT. However, for stronger corrections, it can also have, for example, about 5 mT or about 15 mT.

[0028] According to another preferred embodiment of the invention, the objective lens is a magnetic immersion lens. This can be a weak or a strong immersion lens. Magnetic immersion lenses are typically implemented by having a bore in the outer pole piece of the lens with a larger diameter than the bore in the inner pole piece. In contrast to objective lenses, which provide only a weak magnetic field at the object, immersion lenses have the advantage of achieving lower spherical and chromatic aberrations, but the disadvantage of greater off-axis aberrations. The stronger the magnetic field of the immersion lens and the closer the immersion lens is positioned to the object plane, the stronger the Larmor rotation of the charged particles in the magnetic field.This applies both to the first single-particle beams that hit the object and to the second single-particle beams that are emitted from the object.

[0029] According to a preferred embodiment of the invention, the immersion lens provides a focusing magnetic field which provides a magnetic field strength at the object plane greater than 10 mT, in particular greater than 20 mT, 50 mT and / or 150 mT.

[0030] According to a preferred embodiment of the invention, the second particle optic comprises a projection lens system comprising a first projection lens system and a second projection lens system, wherein the first contrast correction lens is arranged between the first and the second projection lens systems. The first projection lens system may have exactly one projection lens. However, it is also possible for it to have two or more projection lenses. Similarly, the second projection lens system may have exactly one projection lens. However, it is also possible for it to have two or more projection lenses. It is also possible for the projection lens system to include a third projection lens system.Even then, it is preferable that the first contrast correction lens is arranged between the first and second projection lens systems and / or between the first and second projection lenses; the projection lens systems / projection lenses are thus numbered sequentially in the direction of the particle-optical beam path. The first projection lens (the first projection lens system) is often also referred to as the contrast lens (contrast lens system).

[0031] According to a preferred embodiment of the invention, the second particle optic comprises a projection lens system, wherein the first contrast correction lens is arranged between the contrast aperture and the projection lens (contrast lens) nearest to it in the direction opposite to the particle optical beam path. In this case, there is therefore no further projection lens between the first contrast correction lens and the contrast aperture. In existing multi-particle beam systems, there is a relatively large amount of space at this position, so that even a weak contrast correction lens, which will generally have a greater length L, can be arranged there.

[0032] According to a preferred embodiment of the invention, the projection lens system has at least one magnetic projection lens and / or consists of at least one magnetic projection lens.

[0033] According to a further preferred embodiment of the invention, the projection lens system has at least one electric projection lens and / or consists of at least one electric projection lens.

[0034] According to a further embodiment of the invention, the contrast correction lens system comprises a second or further contrast correction lens.

[0035] According to a further embodiment of the invention, the first contrast correction lens and / or a further contrast correction lens is arranged between the objective lens and the beam splitter. The contrast correction lens can be arranged between the objective lens and the upper focal plane of the objective lens. Alternatively or additionally, it is also possible for the contrast correction lens to be arranged between the upper focal plane of the objective lens and the beam splitter. In both of these positions, however, less installation space is available, so shorter and more powerful contrast correction lenses should generally be used. This, of course, also depends on the effects to be corrected caused by the magnetic field of the objective lens. Furthermore, in these installation positions, the contrast correction lens is also penetrated by the first single-particle beams.This fact can be used to precisely adjust even a telecentric impact of the first individual particle beams onto the object plane. The effects on the first and second individual particle beams add constructively; that is, the contrast-correcting lens deflects both beams in the same direction. However, the effects are usually of different magnitudes for the first and second individual particle beams because their energies are generally different.

[0036] According to a preferred embodiment of the invention, the first contrast correction lens and / or a further contrast correction lens is designed as a multi-part component. A contrast correction lens can thus form a subsystem of the multi-lens contrast lens system. The components of a contrast correction lens can be arranged directly one behind the other or separately from one another.

[0037] According to a preferred embodiment of the invention, the multiple particle beam system further comprises a deflector field with a plurality of adjacent deflectors, arranged in the region of an intermediate image plane in the second particle-optical beam path, wherein the deflectors are configured to generate electric and / or magnetic deflection fields of adjustable strength, wherein, during operation, the second single-particle beams penetrate the deflector field and wherein the second single-particle beams are deflected by the deflection fields by deflection angles dependent on the strength of the deflection fields, and wherein the control system is configured to control the strength of the electric and / or magnetic deflection fields. Each deflector is penetrated by a single second single-particle beam or a group of second single-particle beams.

[0038] Such deflector fields are also disclosed in WO 2019 / 243349 A2, the disclosure of which is incorporated in its entirety into this application by reference. The deflector field can also be used to correct the tilting of secondary single-particle beams, so that the secondary single-particle beams can be precisely superimposed at the beam intersection point of the contrast aperture. The deflection angles in question can be greater than 10 µrad, in particular greater than 15 µrad, in particular greater than 100 µrad, and in particular greater than 300 µrad. To determine the deflection angles and / or angles of incidence of a particle beam onto a plane, the so-called heavy beam of the particle beam is usually used. The heavy beam represents the fictitious sum of the trajectories of all particles in the particle beam.

[0039] In this embodiment of the invention, the correction of beam tilts caused by differing azimuthal velocity components can be performed stepwise. This offers advantages when using strong magnetic immersion objective lenses or with large image fields compared to correction solely by deflector fields in the secondary path: In such cases, it is necessary to perform a first tilt correction on the second individual particle beams using the contrast correction lens according to the invention in order to precisely target the deflector field for the required residual correction and to prevent problems with crosstalk between the second individual particle beams.

[0040] According to a preferred embodiment of the invention, the multiple particle beam system further comprises a deflector field with a plurality of adjacent deflectors, which is arranged in the region of an intermediate image plane of the first single particle beams, wherein the deflectors are configured to generate electromagnetic deflection fields of adjustable strength, wherein in operation the first single particle beams penetrate the deflector field and wherein the first single particle beams are deflected by the deflection fields by deflection angles dependent on the strength of the deflection fields, and wherein the control system is configured to control the strength of the electromagnetic deflection fields.

[0041] In this design variant, means for correcting beam tilt in the secondary path (contrast correction lens(es) and optionally a deflector field in the secondary path) are combined with means for correcting beam tilt in the primary path. In the primary path, this correction ensures precisely telecentric illumination of the sample, even when a strong magnetic immersion lens is used as the objective lens. In the secondary path, the correction serves to adjust the homocentricity of the second individual particle beams or the beam bundle at the contrast diaphragm.

[0042] Depending on the position of the (possibly multi-part) contrast correction lens(es) and the deflector field(s), corrections for beam tilts can be made to both the first and second individual particle beams using the same corrective means. These corrective means are then positioned where the first and second particle optical beam paths overlap, i.e., between the sample and the beam splitter, particularly at the positions already explicitly mentioned above. The extent of the correction for the first and second individual particle beams is typically different due to their differing particle energies. A subsequent correction or stepwise correction of at least the beam tilts of the second individual particle beams in the (pure) secondary path is then advantageous.

[0043] WO 2019 / 243349 A2 discloses a first deflector field in the primary path, arranged in an intermediate image plane of the primary particle beam path. The first deflector field is configured to influence the angles of incidence of the primary beams on the sample. By appropriately controlling the individual deflectors of the deflector field, a tilting of the beams by the magnetic immersion lens is maintained, so that they strike the sample telecentrically. A tilting of the secondary beams is then compensated by the contrast-correction lens system according to the invention. Alternative means for influencing the angles of incidence of the primary beams on the sample are also known from German patent application DE 10 2019 004 124 A1, the disclosure of which is incorporated in full by reference into this application: This application discloses a magnetic multi-deflector array for deflecting single-particle beams in the azimuthal direction.The multi-deflector array comprises a combination of a simple aperture plate with a single opening and a multi-aperture plate, which are connected in such a way that a cavity is formed between the two plates. A coil for generating a magnetic field is located in this cavity. This allows for a specific shaping of the magnetic field, enabling the simple and individual adjustment of azimuth angles for each individual particle beam within the particle beam system. This method exploits the fact that an azimuthal (and radial) telecentricity error in magnetic immersion lenses is essentially proportional to the distance of the respective individual particle beam from the optical axis.

[0044] WO 2019 / 243 349 A2 discloses a second deflector field in the secondary path, arranged in an intermediate image plane of the secondary particle beam path. In one embodiment, a first contrast correction lens is arranged in the common beam path and used to compensate for tilting of both the primary and secondary particles. Since these particles experience different tilting due to their energy difference, the first contrast correction lens in the common beam path can be designed such that, for example, the tilting of the primary beams on the sample is compensated, and any residual tilting of the secondary particles is compensated by either a second contrast correction lens in the secondary path or the second deflector field in the secondary path.

[0045] It is also possible to combine a deflector field in the primary or secondary path with a contrast correction lens or lenses in the primary or secondary path. Particularly with a raster array of primary beams with a large number of beams, for example, more than 300 individual beams, very large tilts of the outer beams occur. Here, it is possible to largely compensate for a significant portion of the beam tilt with a contrast correction lens, for example, by 90%, and to compensate for a residual error of, for example, 10% with a deflector field. The deflector field then only needs to be operated at lower voltages.

[0046] According to a preferred embodiment of the invention, each deflector has at least one pair of opposing electrodes between which the second single-particle beams pass through the deflector, and the control system is configured to apply independently adjustable electrical potentials to the electrodes of the pair of electrodes. One pair of opposing electrodes is sufficient for deflections in one direction. The use of several pairs of opposing electrodes allows for more flexible adjustment of the directional correction. Each deflector can have several pairs of opposing electrodes; for example, two, three, or four pairs, each forming four, six, or eight individual electrodes, are common.

[0047] According to a preferred embodiment of the invention, the deflector field has a center, and a connecting line between the centers of the two electrodes of the pair of electrodes of each deflector is oriented circumferentially with respect to the center of the deflector field. With such a deflector field, it is then possible, for example, to influence particle beams whose trajectories have an azimuthal velocity component with respect to the optical axis, such that after passing through the deflector field, the azimuthal velocity component is corrected, so that all individual particle beams superimpose homocentrically in a subsequent beam crossing.

[0048] According to a preferred embodiment of the invention, each deflector has at least a first plate and a second plate arranged one behind the other in the beam path, wherein the first plate has a first opening and the second plate has a second opening through which the second single-particle beams pass, wherein a center of the first opening, viewed in the direction of the beam path, is laterally offset relative to a center of the second opening, and wherein the control is configured to apply different electrical potentials to the first and the second plates. These electric fields then cause the second single-particle beams passing through the openings to be deflected.

[0049] According to a preferred embodiment of the invention, the deflector field has a center and the center of the first opening, seen in the direction of the beam path, is laterally offset in the circumferential direction relative to the center of the second opening with respect to the center of the deflector field.

[0050] According to a preferred embodiment of the invention, the plurality of deflectors of the deflector field have a common first multi-aperture plate with a plurality of first openings and a common second multi-aperture plate with a plurality of second openings, wherein one of the first openings and one of the second openings is penetrated by the second single-particle beams. It is possible that only one second single-particle beam passes through each opening, but it is also possible that a group of second single-particle beams passes through each opening.

[0051] The embodiments of the invention described above can be combined in whole or in part, provided that no technical contradictions arise as a result.

[0052] The invention will be better understood with reference to the accompanying figures. These show: Fig. Figure 1 shows a schematic representation of a particle beam system in the form of a multi-beam particle microscope. Fig. Figure 2 shows a schematic representation of a detail of the particle beam system. Fig. 1 with intermediate image planes and contrast aperture; Fig. 3: schematically illustrates particle-optical images through a symmetrical and an asymmetrical magnetic lens; Fig. Figure 4 shows a schematic representation of a magnetic contrast correction lens; Fig. Figure 5: schematically shows a first arrangement of a magnetic contrast correction lens in a multi-particle beam system; Fig. Figure 6: schematically shows a second arrangement of a magnetic contrast correction lens in a multi-particle beam system; Fig. Figure 7: schematically shows a third arrangement of a magnetic contrast correction lens in a multi-particle beam system; Fig. 8: shows a schematic top view of a deflector field which is used in the particle beam system of the Fig. 1 can be used; Fig. 9: shows a schematic top view of another deflector field, which is part of the particle beam system of the Fig. 1 can be used; and Fig. 10: shows a schematic representation of a cross-sectional view of the in Fig. 9 depicted deflector field along a line VI-VI.

[0053] In the following, the same reference symbols denote the same features, even if these are not explicitly mentioned in the text.

[0054] A particle beam system according to one embodiment is in Fig. Figure 1 is shown schematically. The particle beam system 1 comprises an illumination system 80 with a first particle-optical beam path, which is configured to direct a plurality of first particle beams 3 onto a plane 101 in which an object 7 is arranged. Each of the particle beams 3 illuminates an impact point on the object 7, with the particle beams 3 striking the object 7 side by side and at a distance from one another, so that an array of impact points is illuminated. The particle beams 3 can, for example, be electron beams, which generate secondary electrons and backscattered electrons at the object 7. An imaging optic 90 of a detection system with a second particle-optical beam path is configured to collect the electrons generated at the impact points and direct them onto a detector array 13.Here, electrons emanating from each of the impact points are used to form a separate particle beam 9. The particle beams 9 are directed towards the detector array 13. The detector array 13 comprises an array of detector elements, with one or more detector elements being designated for the detection of each of the particle beams 9. For this purpose, the detector elements are arranged in an array that corresponds to the arrangement of the impact points on the object 7. The imaging optics 90 are configured with respect to the surface of the object 7 and the detector array 13 such that the surface of the object 7 is arranged in an object plane 101 of the image provided by the imaging optics 90, and the detector elements of the detector array 13 are arranged in an image plane 19 of this image.The imaging optics 35 of the illumination system 3 and the imaging optics 90 of the detection system are arranged such that the image plane 101 of the imaging optics 35 and the object plane of the imaging optics 90 coincide, and the surface of the object can be positioned there. The plane 101 is thus the image plane of the illumination system 80, the object plane 17 of the imaging optics 30, and the sample plane in which the surface of an object 7 to be examined is positioned.

[0055] The illumination system 80 comprises a multi-beam particle source 21 with a particle emitter 22 for generating a particle beam 23, which is collimated by one or more condenser lenses 25 and strikes a multi-aperture plate arrangement 27. The multi-aperture plate arrangement 27 comprises at least one multi-aperture plate having a plurality of apertures. The particles of the particle beam 23 passing through the apertures in the multi-aperture plate form the particle beams 3. The multi-aperture plate arrangement 27 is further configured to focus the individual particle beams 3, so that foci 31 of the particle beams 3 are formed in a region around a surface 29. The surface 29 may have a curved shape. Additional lenses 33 influencing the beam path may be provided between the multi-aperture plate arrangement 27 and the surface 29.

[0056] The illumination system 80 further comprises an imaging optic 35, which is configured to image the surface 29 onto the plane 101, such that the surface 29 and the plane 101 are conjugate planes in the sense of an optical image. The imaging optic 35 comprises an objective lens 102, which is the lens of the imaging optic 35 that is located closest to the plane 101. Furthermore, the imaging optic 35 may include additional lenses 39.

[0057] The illumination system 3 directs the particle beams 3 onto the plane 101 such that they strike the plane 101 as orthogonally or perpendicularly as possible, i.e., at an angle of incidence of 90°. However, due to the properties of the lenses 37 and 39, deviations from this relationship occur, so that the particle beams strike the plane 101 at angles of incidence other than 90°. In particular, these directions are not the same for all particle beams 3, but can depend on the position of the respective particle beam 3 within the field of particle beams. The deviation of the angle of incidence from 90° can, for example, be caused by telecentricity errors of the imaging optics 35. Furthermore, the objective lens 102 can provide its focusing effect by means of a magnetic field that extends to the surface of the object 7.Then the trajectories of the particle beams 3 immediately at the surface of the object 7 have the form of spirals. In order to at least partially compensate for such deviations from telecentrity, a deflector field 41 is arranged in this embodiment near the surface 29, which is mapped onto the plane 101. This deflector field 41 can also be omitted.

[0058] The imaging optics 90 comprise the objective lens 102 and several lenses 205, which are arranged in Fig. 1 schematically and in Fig. 2 are shown in greater detail. The imaging optics 90 image the plane 17 onto the plane 19, in which the detector elements of the detector array 13 are arranged, such that three intermediate images 71, 72, and 73 are formed successively along the beam path of the particle beams 15. In addition, the particle beams 15 intersect in a plane 75, which is arranged in the beam path between the intermediate images 72 and 73 (see Fig. 2) In this plane 75 a contrast aperture 511 with a recess 79 is arranged, which serves to filter out particles of the particle beams 9 which would otherwise hit a detector element of the detector field 13, which is different from the detector element(s) which are assigned to the location in the plane 101 from which the particle was started.

[0059] As explained above, the quality of this filtering is reduced if the particle beams 9 do not originate orthogonally from plane 101 or 17, i.e., at angles other than 90°. In practice, this occurs, for example, when the objective lens 102 generates a focusing magnetic field that extends to plane 101.

[0060] To compensate for this, a deflector field 81 can be arranged in the region of the intermediate image 72. This field comprises a series of deflectors, each of which is penetrated by one of the particle beams 9. The deflectors deflect the particle beams 9 penetrating them in such a way that they penetrate the smallest possible area in the plane 75, and the aperture 79 can be chosen to be sufficiently small to achieve good filtering at high throughput.

[0061] The deflector field 81 can have a structure as shown below. Fig. Sections 8 to 10 are explained. However, a deflector field 81 is not required.

[0062] The multi-particle beam system further comprises a computer system 10, which is designed both for controlling the individual particle-optical components of the multi-particle beam system and for evaluating and analyzing the signals acquired with the multi-detector 209. The computer system 10 can be composed of several individual computers or components. It can also control the contrast-correct lens system 500 according to the invention (in Fig. 1 and Fig. 2 not shown).

[0063] Further information on such multi-beam particle beam systems and components used therein, such as particle sources, multi-aperture plates and lenses, can be obtained from the international patent applications WO 2005 / 024881 A2, WO 2007 / 028 595 A2, WO 2007 / 028 596 A1, WO 2011 / 124 352 A1 and WO 2007 / 060 017 A2 and the German patent applications DE 10 2013 016 113 A1 and DE 10 2013 014 976 A1, the disclosure of which is incorporated in full by reference into the present application.

[0064] Fig. Figure 3 schematically illustrates particle-optical imaging through a symmetrical and an asymmetrical magnetic lens and is intended to illustrate the occurrence of beam tilting. Fig. 3a) The image formed by a symmetrical magnetic lens, e.g., a magnetic objective lens 102, is shown. The z-component Bz of the magnetic field generated by the lens is plotted on the y-axis. The object to be imaged, G, is located in front of the magnetic objective lens 102 with respect to the optical axis Z and is represented by an upright arrow. The particle-optical image B is formed behind the magnetic objective lens 102. The object to be imaged, G, is located outside the magnetic field of the objective lens 102. An example of a particle-optical ray path for a parallel ray, which is imaged through the focal point F in the focal plane E, is shown. The central ray is also shown.

[0065] Below the schematically sketched beam paths through the objective lens 102 is now the azimuthal velocity component v. azimutalThe image shows a field beam originating perpendicularly from the sample. The off-axis electrons belonging to this field beam, which start perpendicularly from the sample (i.e., without an azimuthal velocity component), rotate within the lens and exit the lens field without any azimuthal velocity component. Consequently, the electrons converge in the focal plane, and a contrast aperture (not shown) allows for precise filtering of the electrons in the focal plane according to their starting angles. This filtering enables homogeneous contrast even across a large image field.

[0066] In Fig. 3b) For comparison, the particle-optical beam path is shown for the case where the magnetic lens 102 is a magnetic immersion lens. In this case, the object G to be imaged, or a sample, is located within the magnetic field of lens 102. The magnetic field that the electrons experience and traverse is therefore not symmetrical, but asymmetrical. The azimuthal velocity component v azimutalThe velocity is not zero after passing through lens 102. An off-axis electron, which starts perpendicular to the sample (i.e., without an azimuthal velocity component), rotates within the magnetic lens 102 and exits the lens field with an azimuthal velocity component due to the asymmetry. This azimuthal velocity component leads to a tilting of the electron beams or secondary beams. Consequently, electrons launched parallel from the sample no longer converge homocentrically in the focal plane E. It is no longer possible to perform high-precision filtering based on launch angles in the focal plane. This results in errors and, consequently, contrast drift across the image field.

[0067] The Fig. Figure 4 shows a schematic representation of a magnetic contrast correction lens 500. Fig. 4 The contrast correction lens 500 according to the invention is arranged in the particle-optical beam path downstream of a magnetic projection lens 205. This projection lens 205 can be one of several projection lenses of a projection lens system. It would also be possible that another particle-optical lens, e.g., an objective lens 102, is provided instead of the projection lens 205. Fig. In this respect, figure 4 serves only to illustrate and to better understand the inventive concept.

[0068] The magnetic contrast correction lens 500 is thus positioned in an area where the bundle of two single-particle beams converges.

[0069] In Fig. Figure 4 shows, as an example, the beam paths of three second single-particle beams 9a, 9b, and 9c. The projection lens 205 is a high-refractive-index lens. The second single-particle beams 9a, 9b, and 9c are thus focused onto the beam crossing point 510. The magnetic contrast correction lens 500, on the other hand, is a magnetic lens with a weak magnetic field. The magnetic field is effective in the region 501 and in Fig. In section 4, the direction of the magnetic field is indicated by arrows. Essentially, the magnetic field is aligned parallel to the optical axis Z; this is denoted by B. z indicated on one of the arrows.

[0070] The charged second single-particle beams or electrons 9a, 9b and 9c exhibit different radial velocity components. Regarding velocity components in the radial direction v r It works - mediated by the magnetic field Bz - the Lorentz force F L This leads to a spiral motion of the charged particles in the magnetic field 501. The spiral motion of the charged particles is stronger, or rather the Lorentz force is stronger, the further a charged particle beam 9a, 9b and 9c is from the optical axis Z, since the velocity component v is higher here. ris larger. By means of appropriate control via the controller 10.1, the magnetic field 501 of the contrast correction lens 500 can be selected such that the Larmor rotation generated here counteracts the azimuthal tilt caused, for example, by the magnetic immersion lens. The contrast correction lens must now be adjusted so that particles launched from the sample at the same angles and energies, for example, perpendicular to the surface of a semiconductor wafer, meet again at the beam intersection, and the Larmor rotation or remanent tilt of the individual particle beams is exactly compensated. For this compensation, it is sufficient if the charged particles in the magnetic field 501 complete less than a full rotation or helix. Accordingly, the magnetic field 501 can be selected to be weak, provided that a sufficient drift distance is available within the magnetic field.In the example shown, the drift distance or length L of the contrast correction lens 500, and thus of the effective magnetic field 501 generated by it, is approximately 20 cm. However, it could also be 10 cm or 30 cm; other lengths are also possible. In the example shown, the radius r of the magnetic field is approximately 5 cm.

[0071] Upon exiting the magnetic field 501, the undesired tilting of the second single-particle beams 9a, 9b, and 9c caused by the magnetic field of the magnetic immersion lens is exactly compensated. Thus, in the beam crossing 510, the second single-particle beams 9a, 9b, and 9c can be precisely superimposed. This makes it possible to filter the second single-particle beam according to its starting angle distribution on the sample using a contrast aperture (not shown). In one example, filtering is performed according to the central beam of every second single-particle beam, with the central beams being oriented perpendicular to the surface of a semiconductor wafer arranged in the plane 101.

[0072] The Fig. 5, Fig. 6 and Fig. Figure 7 schematically shows a first, a second, and a third arrangement of a magnetic contrast-correcting lens 500 in a multi-particle beam system 1. The object G, or a sample, is located within the magnetic field of the objective lens, which is, for example, a strong magnetic immersion lens 102. Due to Larmor rotation, the second individual particle beams 9a, 9c are slightly tilted azimuthally after leaving the immersion lens 102, so that they would not meet exactly at the beam crossing 510 without the contrast-correcting lens 500 according to the invention. The second individual particle beams 9a, 9c emanating from the sample then pass through the beam splitter 400 and subsequently a projection lens system 205, which in the example shown comprises three projection lenses 205a, 205b, and 205c. The example shown consists of magnetic projection lenses 205a, 205b and 205c.However, it would also be possible to use electric or electromagnetic projection lenses. In this embodiment, the contrast correction lens 500 is arranged within the projection lens system 205. Specifically, it is located between the first projection lens 205a and the second projection lens 205b, or in other words, between the projection lens 205a, which is arranged in the particle-optical beam path upstream of the contrast aperture 511 and the beam crossing 510, and the contrast aperture 511. At this point, there is normally sufficient installation space in multi-particle beam systems 1 to arrange a relatively long contrast correction lens 500 in the second particle-optical beam path.

[0073] In the example shown, the particle-optical components in the second particle-optical beam path are controlled by components of the control unit 10, specifically components 10.1, 10.2, and 10.3. This targeted control makes it possible to optimize the particle-optical beam path and, in particular, to ensure that the second individual particle beams 9a and 9c are precisely homocentrically aligned at beam crossing 510 by means of exact compensation of the Larmor rotation using the contrast correction lens.

[0074] In Fig. In step 6, the position of the contrast correction lens 500 is different than in the one described above. Fig. In the embodiment shown in Figure 5: The contrast correction lens 500 is located between the objective lens 102 and the beam splitter 400. Specifically, the contrast correction lens 500 is arranged between the objective lens 102 and the upper focal plane 502 of the objective lens 102. In this embodiment, compensation for the Larmor rotation is performed immediately after the unwanted azimuthal tilt of the individual particle beams occurs. However, due to the limited space available, a stronger magnetic field must be used to compensate for the Larmor rotation when the contrast correction lens 500 according to the invention is positioned in this way.

[0075] At the in Fig. In the embodiment shown in Figure 7, the contrast correction lens 500 according to the invention is also located between the objective lens 102 and the beam splitter 400. However, in this embodiment, the contrast correction lens 500 is arranged between the upper focal plane 520 of the objective lens 102 and the beam splitter 400. In this area, the second individual particle beams diverge, so that, compared to the two other embodiments, the Fig. 5 and Fig. 6 the direction of the magnetic field within the contrast correction lens 500 must be reversed.

[0076] It is also possible to see the examples of the implementation of the Fig. 5, Fig. 6 and Fig. 7. to combine them wholly or partially. The contrast correction lens system can then include a first, second, and / or third contrast correction lens, or even more contrast correction lenses. Each contrast correction lens can be designed as a single unit or in multiple parts. Furthermore, the embodiments of the Fig. 5, Fig. 6 and Fig. 7 wholly or partly with the in Fig. 7, Fig. 8 and Fig. The 9 described embodiments of the deflector fields 41 are combined.

[0077] In Fig. Figure 8 is a schematic top view of an embodiment of the deflector field 41. Such a deflector field 41 can be arranged in an intermediate image plane of the first and / or second particle-optical beam path and allows individual directional correction of particle beams. Deflection angles can be individually adjusted by means of a control system.

[0078] The deflector field 41 comprises a multi-aperture plate 43, which has a plurality of openings 45 arranged in a field 46 such that each opening 45 is centrally penetrated by one of the second single-particle beams 9. At least one pair of opposing electrodes 47 is arranged on either side of the center of each opening 45. Each electrode 47 is connected to a controller 10.4, which is configured to apply different electrical potentials to the electrodes 47 of each pair of electrodes. The potential difference between the electrodes 47 of a pair of electrodes 47 generates an electric field between the electrodes 47, which deflects the particle beam 9 penetrating the pair of electrodes 47 by an angle that depends on the potential difference.

[0079] The pairs of electrodes 47 are oriented with respect to the particle beams 5 passing through them such that a connecting line 51 between the centers of the two electrodes 47 of the pair is arranged circumferentially with respect to a center 53 of the field 46 of the openings 45 through which the particle beams 5 pass. This makes it possible to deflect the particle beams 5 in such a way that the effect of a magnetic field extending from the objective lens 102 to the surface of the object 9 is compensated.

[0080] At the in Fig. In the deflector field 41 shown in Figure 8, each individual deflector has a pair of opposing electrodes 47, which are arranged circumferentially offset with respect to the center 53. This makes it possible to deflect the particle beams in directions oriented circumferentially with respect to the center. However, it is also possible to arrange two or more pairs of opposing electrodes distributed circumferentially around the opening in order to also be able to adjust the orientations into which the particle beam passing through the multiple pairs of electrodes is deflected.

[0081] Another embodiment of a deflector field 41 is described below with reference to the Fig. 9 and Fig. 10 explained. Here we show Fig. 9 a top view of the deflector field 41 and Fig. 10 a cross-section through the deflector field 41 along a line VI-VI of the Fig. 9.

[0082] The deflector field 41 comprises a first multi-aperture plate 56, which has a plurality of openings 45, and a second multi-aperture plate 57, which has a plurality of openings 45', through which the particle beams 5 pass. The two multi-aperture plates 56 and 57 are arranged one behind the other in the beam path, such that each particle beam 5 first passes through an opening 45 in the first multi-aperture plate 56 and then through an opening 45' in the second multi-aperture plate 57. The openings 45 and 45' in the two multi-aperture plates 56 and 57 can each have the same diameter. However, this need not be the case.

[0083] The two multi-aperture plates 56 and 57 are arranged relative to each other such that the center of the aperture 45 through which a given particle beam passes in the first multi-aperture plate 56 is laterally offset relative to the center of the aperture 45' through which this particle beam passes in the second multi-aperture plate 57, viewed in the direction of the beam. This is in the Fig. 8 is represented by the fact that the openings 45 in the first multi-aperture plate 56 are completely visible and are shown as solid lines, while the openings 45' in the second multi-aperture plate 57 are partially obscured and, where visible, are shown with solid lines, and where obscured, are shown with broken lines.

[0084] A controller 10.5 is configured to apply different electrical potentials to the first multi-aperture plate 56 and the second multi-aperture plate 57. This generates electrostatic fields between the multi-aperture plates 56 and 57, which deflect the particle beams 5. The deflection angle can be adjusted by the potential difference between the multi-aperture plates 56 and 57, which is determined by the controller 10.5.

[0085] The deflector field has a center 53 around which the second multi-aperture plate 57 is rotated relative to the first multi-aperture plate 56, as indicated by an arrow 61 in Fig.Figure 8 is shown. This rotation creates a lateral displacement in the circumferential direction around the center 53 between the openings 45 and 45', which are successively penetrated by the particle beam 9, whereby this lateral displacement in the circumferential direction increases with increasing distance of the respective openings 45 and 45' from the center 53. Reference symbol list 1 multi-beam particle microscope 3 primary particle beams (single-particle beams) 7 objects 9 secondary particle beams 10 Computer system, control system with multiple components 13 Detector field 19 Level of detector elements 21 Multibeam particle source 22 particle emitters 23 Particle beam 25 condenser lenses 27 multi-aperture plate array 29 Area of ​​the foci 31 Foci 33 lenses 35 Imaging optics 39 lens 41 Deflector field 43 Multi-aperture plate 45 opening 46th field 47 Electrode 51 connecting line 53 Center 56 first multi-aperture plate 57 second multi-aperture plate 67 Region of a homogeneous magnetic field 71 Intermediate image 72 Intermediate frame 73 Intermediate image 75 Plane of beam crossing 79 Opening 80 Lighting system 81 Deflector field 90 Imaging optics 101 Object level 102 lens 205 Projection lens 206 Area Magnetic field 400 beam switch 500 contrast correction lens 501 Area Magnetic field 510 beam crossing 511 Contrast aperture 520 Beam crossing in the upper focal plane of the objective lens Z optical axis G Subject B image Bz magnetic field L Length of the effective magnetic field r radius of the effective magnetic field

Claims

[1] A multi-particle beam system (1) comprising: a multi-beam particle source (21) configured to generate a first field of a plurality of charged first particle beams (3); a first particle optic (80) with a first particle-optical beam path, which is configured to image the generated individual particle beams (3) onto an object plane (101) so that the first particle beams (3) strike an object (7) at impact locations that form a second field; a detection system (13) having a plurality of detection areas forming a third field; a second particle optic (90) with a second particle-optical beam path, which is configured to image (102) second single-particle beams (9) emanating from the impact locations in the second field onto the third field of the detection regions of the detection system (13); a magnetic objective lens (102), in particular a magnetic immersion lens, through which both the first (3) and the second single particle beams (9) pass; a beam switch (400) arranged in the first particle-optical beam path between the multi-beam particle source (21) and the objective lens (102), and arranged in the second particle-optical beam path between the objective lens (102) and the detection system (13); and a controller (10); wherein a beam crossing (510) of the second individual particle beams (9) takes place in the second particle-optical beam path between the beam switch (400) and the detection system (13), wherein in the region of the beam crossing (510) a contrast aperture (511) with a central recess for filtering the second individual particle beams (9) according to their starting angles from the object plane (101) is arranged, wherein in the second particle-optical beam path between the objective lens (102) and the contrast aperture (511) a contrast correction lens system (500) with a first magnetic contrast correction lens (500) is arranged, which is configured to generate a magnetic field of adjustable strength and to correct beam tilts of the second individual particle beams (9) in the beam crossing (510) relative to the optical axis (Z) of the multiplicity particle beam system (1), and wherein the controller (10) is configured to control the excitation of the contrast correction lens system (500). [2] A multiplicity particle beam system (1) according to claim 1, wherein the first magnetic contrast correction lens (500) is arranged in a region in which the second single particle beams (9) converge or divergently during operation of the multiplicity particle beam system (1). [3] A multiplicity particle beam system (1) according to any one of the preceding claims, wherein the excitation of the contrast correction lens system (500) is controlled such that the second individual particle beams (9) have substantially no azimuthal velocity components after passing through the contrast correction lens system (500) in a subsequent image plane or intermediate image plane (71, 72, 73) of the second particle-optical beam path. [4] A multi-particle beam system (1) according to any one of the preceding claims, wherein the excitation of the contrast correction lens system (500) is controlled such that all second single particle beams (9) pass through the beam crossing (510) centrally with respect to the optical axis (Z) of the system (1). [5] A multi-particle beam system (1) according to any one of the preceding claims, wherein the magnetic field of the first contrast correction lens (500) inside the lens (500) is aligned substantially parallel to the optical axis (Z) of the system (1). [6] A multi-particle beam system (1) according to any one of the preceding claims, wherein the length L of the first contrast correction lens (500) is greater than the radius r of the contrast correction lens (500), i.e. L > r. [7] A multi-particle beam system (1) according to the preceding claim, wherein the length L of the first contrast correction lens (500) is at least twice as large as the radius r of the contrast correction lens (500), i.e. L ≥ 2r. [8] A multi-particle beam system (1) according to any one of the preceding claims, wherein the length L of the first contrast correction lens (500) is at least 15 cm, in particular at least 20 cm and / or at least 30 cm. [9] A multi-particle beam system (1) according to any one of the preceding claims, wherein the objective lens (102) is a magnetic immersion lens. [10] A multi-particle beam system (1) according to the preceding claim, wherein the immersion lens (102) provides a focusing magnetic field having a magnetic field strength at the object plane (101) that is greater than 10 mT, in particular greater than 20 mT, 50 mT and / or 150 mT. [11] Multiparticle beam system (1) according to one of the preceding claims, wherein the second particle optics (90) comprises a projection lens system (205) comprising a first projection lens system (205a) and a second projection lens system (205b), and wherein the first contrast correction lens (500) is arranged between the first (205a) and the second (205b) projection lens system of the projection lens system (205). [12] Multiparticle beam system (1) according to one of the preceding claims, wherein the second particle optics (90) comprises a projection lens system (205), and wherein the first contrast correction lens (500) is arranged between the contrast aperture (511) and the projection lens (205a) closest to it in the direction opposite to the particle-optical beam path. [13] A multi-particle beam system (1) according to any one of claims 11 to 12, wherein the projection lens system (205) comprises at least one magnetic projection lens (205a, 205b, 205c). [14] A multi-particle beam system (1) according to any one of claims 11 to 13, wherein the projection lens system (205) comprises at least one electric projection lens. [15] A multi-particle beam system (1) according to any one of the preceding claims, wherein the contrast correction lens system (500) comprises a second or further contrast correction lens. [16] A multi-particle beam system (1) according to any one of the preceding claims, wherein the first contrast correction lens (500) and / or a further contrast correction lens is arranged between the objective lens (102) and the beam splitter (400). [17] A multi-particle beam system (1) according to any one of the preceding claims, wherein the first contrast correction lens (500) and / or a further contrast correction lens is arranged between the objective lens (102) and the upper focal plane (520) of the objective lens (102). [18] A multi-particle beam system (1) according to any one of the preceding claims, wherein the first contrast correction lens (500) and / or a further contrast correction lens is arranged between the upper focal plane (520) of the objective lens (102) and the beam switch (400). [19] A multi-particle beam system (1) according to any one of the preceding claims, wherein the first contrast correction lens (500) and / or a further contrast correction lens is formed in several parts. [20] Multiparticle beam system (1) according to one of the preceding claims, which further comprises a deflector field (81) with a plurality of deflectors arranged side by side, which is arranged in the region of an intermediate image plane (72), wherein the deflectors are configured to generate electromagnetic deflection fields of adjustable strength, wherein in operation the second single-particle beams (9) pass through the deflector field (81) and wherein the second single-particle beams (9) are deflected by the deflection fields by deflection angles dependent on the strength of the deflection fields, and wherein the controller (10) is configured to control the strength of the electromagnetic deflection fields. [21] Multiparticle beam system (1) according to one of the preceding claims, which further comprises a deflector field (41) with a plurality of deflectors arranged next to one another, which is arranged in the region of an intermediate image plane (29), wherein the deflectors are configured to generate electromagnetic deflection fields of adjustable strength, wherein in operation the first single particle beams (3) pass through the deflector field and wherein the first single particle beams (3) are deflected by the deflection fields by deflection angles dependent on the strength of the deflection fields, and wherein the controller (10) is configured to control the strength of the electromagnetic deflection fields. [22] A multi-particle beam system (1) according to claim 20 or 21, wherein each of the deflectors comprises at least one pair of mutually opposing electrodes (47) between which the first (3) or second (9) single particle beams pass through the deflector, and wherein the controller (10) is configured to apply mutually different adjustable electrical potentials to the electrodes of the pair of electrodes. [23] A multi-particle beam system (1) according to the preceding claim, wherein the deflector field (41, 81) has a center (53), and wherein a connecting line (51) between centers of the two electrodes of the pair of electrodes of each deflector is oriented circumferentially with respect to the center of the deflector field (41, 81). [24] A multi-particle beam system (1) according to claim 20 or 21, wherein each of the deflectors comprises at least a first plate (56) and a second plate (57) arranged one behind the other in the beam path, wherein the first plate has a first opening (45) and the second plate has a second opening (45') through which the second single-particle beams (9) pass, wherein a center of the first opening, viewed in the direction of the beam path, is laterally offset (61) relative to a center of the second opening, and wherein the controller (10) is configured to apply different electrical potentials to the first (56) and second (57) plates. [25] A multi-particle beam system (1) according to the preceding claim, wherein the deflector field (41, 81) has a center (53), and wherein the center of the first opening (45), viewed in the direction of the beam path, is offset relative to the center of the second opening (45') in the circumferential direction with respect to the center (53) of the deflector field (41, 81). [26] Multiparticle beam system (1) according to one of the two preceding claims, wherein the plurality of deflectors of the deflector field (41, 81) have a common first multi-aperture plate (56) with a plurality of first openings (45) and a common second multi-aperture plate (57) with a plurality of second openings (45'), wherein one of the first openings (45) and one of the second openings (45') is penetrated by the second individual particle beams (9).

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