Method for designing a multi-beam particle beam system with monolithic path correction plates, computer program product and multi-beam particle beam system

Abstract

A method for designing a multi-beam particle microscope and a multi-beam particle microscope are disclosed. The microscope operates with a multitude of charged single-particle beams, imaging them onto a plane, and features a plurality of path correction plates. Each path correction plate has a plurality of apertures for the multitude of single-particle beams, and during operation of the multi-beam particle microscope, exactly one adjustable correction voltage is applied to each path correction plate. A path correction plate is permanently assigned to a specific operating parameter of the multi-beam particle microscope. During the design of the path correction plates, the apertures in the path correction plates are adapted with respect to shape and size so that path deviations of all single-particle beams related to operating parameters can be corrected.

Description

Field of the invention

[0001] The invention relates generally to multi-beam particle beam systems and, more particularly, to multi-beam particle microscopes operating with a plurality of charged single-particle beams. Specifically, the invention relates to a method for designing a multi-beam particle beam system with monolithic trajectory correction plates, to a corresponding computer program product, and to a correspondingly designed multi-beam particle beam system. 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 the analysis of semiconductor wafers 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 over a very large area in a short time.For several applications, the specification requirement for the accuracy of a measurement provided by an inspection device is even higher, for example, by a factor of two or an order of magnitude. For example, a semiconductor feature width must be measured with an accuracy below 1 nm, such as 0.3 nm or even less, and a relative position of semiconductor structures must be determined with an overlay accuracy below 1 nm, such as 0.3 nm or even less.

[0004] A recent development in the field of charged particle microscopes (CPM) is the MSEM, a multi-beam scanning electron microscope. A multi-beam scanning electron microscope is disclosed, for example, in US Pat. No. 7,244,949 B2 and US Pat. No. 2019 / 0,355,544 A1. In a multi-beam electron microscope, or MSEM, a sample is simultaneously irradiated with a plurality of single electron beams arranged in a field or grid. For example, 4 to 10,000 single electron beams can be provided as primary radiation, with each single electron beam separated from a neighboring single electron beam by a distance of 1 to 200 micrometers. For example, an MSEM has approximately 100 separate single electron beams (beamlets), arranged, for example, in a hexagonal grid, with the single electron beams separated by a distance of approximately 10 µm.The plurality of charged single-particle beams (primary beams) are focused by a common objective lens onto the surface of a sample under investigation. The sample can be, for example, a semiconductor wafer attached to a wafer holder mounted on a movable stage. During illumination of the wafer surface with the charged primary single-particle beams, interaction products, such as secondary electrons or backscattered electrons, emanate from the wafer surface. Their starting points correspond to the locations on the sample on which the plurality of primary single-particle beams are respectively 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 contains multiple detection pixels, and the detector records an intensity distribution for each of the secondary single-particle beams. This results in an image field of, for example, 100 µm × 100 µm.

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

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

[0007] The use of particle-optical components generally results in imaging errors. These include, for example, field curvature and field astigmatism.

[0008] As imaging quality demands increase, so do the requirements for the multibeam particle microscope used for imaging. For example, to achieve very good resolution in a multibeam particle microscope, field curvature in the object plane must be minimized. The first step is to optimize the electron optics or charged particle optics of the multibeam particle microscope. However, these measures have a limit due to the Scherzer theorem. This limit is insufficient for today's beam uniformity requirements.

[0009] Therefore, the prior art proposes the use of active devices for individual focal length adjustment per beam, e.g., arrays of individually addressable ring electrodes as the active parts of micro-lens arrays. The focal length of an individual micro-lens is approximately quadratically dependent on the voltage applied to the respective lens electrode. However, these active devices for correcting the field curvature per individual particle beam are difficult to produce and expensive. It is essential that each individual micro-correction device functions perfectly; otherwise, this type of correction device is not useful.Furthermore, it is challenging, for example, to supply each micro-lens array with a voltage on the order of more than 50 V, more than 100 V, or even more than 400 V. This poses serious isolation problems, and current active correction devices have a very limited lifetime. Examples of active correction devices can be found in, for example, US 5 834 783 A, US 6 483 120 B1, US 6 903 353 B2, US 7 126 141 B2, and US 11 145 485 B2.

[0010] An alternative approach proposes the use of passive devices, e.g., arrays of monolithic single-lens systems, where only a single drive voltage is provided for the entire array. It is known that the focal length of a single lens is approximately proportional to the diameter of the aperture of the central electrode of the single lens. Therefore, by appropriately varying the diameters of the apertures in a multi-aperture plate that is part of the single-lens array, individual focal length variation per single-particle beam can also be achieved. By applying a single drive voltage to the multi-hole plate with different hole diameters, the field curvature and also field tilt can be corrected. Examples of such passive correction devices can be found, for example, in JP S60-05229 A, US 10 504 681 B2, US 10 784 070 B2, and US 11 139 138 B2.Further examples are disclosed in US 10 923 313 B1 and US 11 322 335 B2.

[0011] It is also known to correct field astigmatism using a monolithic multi-aperture plate. US Pat. No. 7,554,094 B2 shows elliptical apertures whose semi-major axis increases with increasing distance from a central aperture or center point, with the semi-major axis oriented perpendicular to a longitudinal axis of elliptical beam spots that would be formed in an object plane without appropriate correction.

[0012] US 10 923 313 B1 discloses monolithic multi-aperture plates, each of which has exactly one voltage applied to it, and which have either circular apertures of different sizes or elliptical apertures of different sizes. In the elliptical apertures, a ratio Q of the major semi-axis to the minor semi-axis scales with the distance r from a central aperture in the plate (radial variation) or along the x or y direction (Cartesian variation). In order to correct an aberration with high accuracy, it is proposed to use a plurality of monolithic multi-aperture plates that simulate terms of a polynomial that expands aberrations or their correction into a series. Several plates in series with an individual scaling of the aperture diameters for each plate, e.g., in a first plate according to r, in a second plate according to r 2 , in a third plate according to r 3 , in a fourth plate according to r 4etc. correct, for example, field curvature, or multiple plates in series with individual scaling of the Q ratio for each plate correct, for example, field astigmatism. The more precise the correction of aberrations needs to be, the more monolithic multi-aperture plates are required for the correction.

[0013] US 2011 / 0 147 605 A1 discloses multiple plate sequences, each with an aperture of a specific geometry, for correcting aberrations, each of which generates a multipole field. Specifically, US 2011 / 0 147 605 A1 describes, as an example, a hexapole corrector for correcting spherical aberrations. This aberration is rotationally symmetrical. In connection with multi-particle beam systems, US 2011 / 0 147 605 A1 discloses a system with multiple emitter tips for generating a plurality of particle beams. Sequences of multiple multi-aperture plates, each with multiple apertures of a specific geometry, are interspersed with the generated plurality of particle beams. Description of the invention

[0014] It is therefore an object of the invention to improve and / or simplify the correction of image aberrations in multi-beam particle beam systems, and in particular in multi-beam particle microscopes. The correction should be precise and elegant. Ideally, the correction elements should be easy to manufacture and / or easy to integrate into multi-beam particle beam systems.

[0015] This object is achieved by the subject matter of the independent patent claims. Advantageous embodiments of the invention emerge from the dependent patent claims.

[0016] The present invention uses monolithic multi-aperture plates as aberration correction elements, as does the prior art. However, the design and layout of monolithic multi-aperture plates or trajectory correction plates involve a strategic shift in several respects: A disadvantage of the known monolithic multi-aperture plates is that after their manufacture there is only one free parameter that can be varied for the purpose of correcting aberrations, namely the voltage applied to the plate. The parameter that can be varied within the existing monolithic multi-aperture plates is also only a single parameter, namely the aperture size. The shape of the aperture is fixed. The present invention breaks away from this definition: In order to design a monolithic multi-aperture plate or trajectory correction plate, according to the invention not only the size of the apertures in a plate is varied, but also the respective shape of the apertures. Within the scope of a design process there are therefore at least two freely selectable parameters for each aperture in the plate and not just a single parameter.

[0017] In addition, the invention provides a kind of base change: Instead of providing one plate, or rather a sequence of plates, to correct a specific category of aberration (field curvature, astigmatism correction, image plane tilt, etc.), the invention involves designing the monolithic multi-aperture plates to correct aberrations when certain operating parameters change. The plates to be designed are thus specifically adapted to the respective multi-beam particle beam system. This allows for very good aberration corrections with fewer, and possibly significantly fewer, monolithic multi-aperture plates overall.

[0018] Specifically, according to a first aspect, the invention relates to a method for designing a multi-beam particle beam system, in particular a multi-beam particle microscope, which operates with a plurality of charged individual particle beams and images them into an object plane and which has a plurality of trajectory correction plates, wherein each of the trajectory correction plates has a plurality of apertures for the plurality of individual particle beams and wherein, during operation of the multi-beam particle beam system, exactly one adjustable correction voltage is applied to each of the trajectory correction plates to generate a contribution to the trajectory correction, the method comprising the following steps: Defining operating parameters that describe an operating state of the multi-beam particle beam system; Defining operating parameter intervals for each operating parameter in which possible values ​​of the respective operating parameter lie during operation of the multi-beam particle beam system; Determining a single-particle beam trajectory deviation from an ideal single-particle beam trajectory for each operating parameter along its operating parameter interval for each of the single-particle beams; and Laying out the path correction plates, whereby each operating parameter is assigned a path correction plate, and wherein for each trajectory correction plate, the sizes of its apertures are determined based on the determined trajectory deviations of the associated individual particle beams along the operating parameter interval, and wherein for each trajectory correction plate, the shapes of the respective apertures are determined based on the respectively determined trajectory deviations of the associated individual particle beams along the operating parameter interval, so that path deviations that occur due to changes in an operating parameter within its operating parameter interval can be corrected by applying exactly one correction voltage to the path correction plate that is assigned to this operating parameter.

[0019] In this patent application, the terms "trajectory correction plate" and "monolithic multi-aperture plate" are used synonymously. The number of trajectory correction plates is at least two, but more trajectory correction plates can of course also be provided, for example three, four, five, six, seven, eight, nine, or ten trajectory correction plates. Preferably, there are fewer than ten trajectory correction plates, most preferably five or fewer trajectory correction plates. The number of apertures per trajectory correction plate is matched to the number of individual particle beams of the multi-beam particle beam system to be designed. The trajectory correction plates are provided one after the other in the particle-optical beam path; however, they do not have to be provided directly one after the other; their position can be varied and optimized during the design process.Preferred positions of path correction plates will be discussed in more detail below.

[0020] The operating parameters describe an operating state of the multi-beam particle beam system. When defining the operating parameters, it is not necessarily the case that all operating parameters that describe an operating state of the multi-beam particle beam system are also defined within the scope of the method according to the invention. Rather, it is a matter of selecting operating parameters whose change has an influence or a significant influence on trajectory deviations of the individual particle beams from the ideal particle beam trajectories. At least two operating parameters are defined, but three, four, or more operating parameters can naturally also be defined. Examples of operating parameters include the beam current, the landing energy, and the beam spacing of the individual particle beams. Further examples are explained in more detail below.

[0021] When defining operating parameter intervals for each operating parameter, the limits within which an operating parameter may or should change during operation of the multi-beam particle beam system are determined. It is not necessary for the operating parameters to be continuously variable within the intervals. Rather, the aim is to ensure that all values ​​that the operating parameters can assume during operation of the multi-beam particle beam system, which can be adjusted accordingly by a user, are covered by the operating parameter intervals.

[0022] According to the invention, a single-particle beam trajectory deviation from an ideal single-particle beam trajectory is determined for each of the individual particle beams along its operating parameter interval. This trajectory deviation can be determined, for example, by a corresponding particle-optical simulation. However, it is also possible for corresponding measurements to be performed on a multi-beam particle beam system to be designed. The trajectory deviations of the individual particle beams are determined relative to a reference position in the particle-optical beam path, typically when the individual particle beams impinge on an object plane.However, it is also conceivable in principle that a different plane in the particle-optical beam path is selected as the reference position or reference plane, for example in front of particle-optical elements that require precise passage of the individual particle beams, such as filigree multi-beam deflectors. The ideal single-particle beam trajectory can, for example, be selected such that the diameter of the single-particle beam is minimal upon impact in an object plane, i.e. the object plane passes exactly through the beam waist. Additionally or alternatively, an ideal single-particle trajectory can be selected such that the beam diameter is perfectly round or stigmatic. According to the invention, the trajectory deviation is determined for each of the individual particle beams, specifically for each operating parameter along its operating parameter interval.During this determination, the operating parameter is varied; at least two values ​​of an operating parameter are measured or simulated; however, it is also possible to run through the entire operating parameter interval, so to speak. It should be emphasized again at this point that the trajectory deviations of the individual particle beams exhibit a field profile with the inventive type of fine correction. Global corrections, i.e., corrections equally required for all individual particle beams, do not have to be corrected using the monolithic multi-aperture plates or trajectory correction plates; they can be pre-corrected using global corrections.

[0023] When designing the trajectory correction plates, a trajectory correction plate is assigned to each operating parameter according to the invention. Preferably, exactly one trajectory correction plate is assigned to each operating parameter, thus creating a 1:1 assignment. However, it is also possible to assign two trajectory correction plates to one operating parameter if, for example, it is not possible to correct the trajectory deviations caused by changes to this operating parameter within one trajectory correction plate. However, this is only very rarely the case. In the vast majority of cases, changing an operating parameter requires a trajectory correction that is largely independent of the current setting of other operating parameters. This helps to reduce the number of trajectory corrections required for the system overall.In some cases, it is even possible to encode multiple operating parameters in a single trajectory correction plate. However, even in the case where operating parameters are not independent of each other, in the sense that the resulting trajectory corrections are not independent of each other, it is still possible to determine a basis set of trajectory correction plates by solving a multidimensional optimization problem that covers the entire possible state space of the multi-beam particle beam system while simultaneously minimizing the number of trajectory correction plates.

[0024] According to the invention, when designing the trajectory correction plates, not only the size of the apertures is varied, but also their shape. The goal is therefore, in principle, to find the aperture that best performs the desired trajectory correction for the respective individual particle beam along the operating parameter interval. The value of the operating parameter is reflected by the voltage applied to the trajectory correction plate.

[0025] The terms size and shape can be defined in different ways. For circular apertures, the definition is naturally simple: the size can be specified as the diameter of the aperture, for example, and the shape itself as circular. But even with an elliptical or oval aperture, the size of the aperture and the shape of the aperture can be defined in different ways. Reference is possible to the major semi-axis of an ellipse, to a minor semi-axis of the ellipse, to a ratio of the major semi-axis to the minor semi-axis, or to the total area of ​​the opening. For three-fold or four-fold shapes, there are even more ways to define size and shape. However, these definitions are not really decisive for the patent application: As already explained above, the goal is to determine the ideal aperture. In principle, this means the greatest possible freedom in finding the aperture.So there is definitely more than one degree of freedom for determining the aperture. This is an important difference compared to the state of the art. At this point, it should also be noted that a circular aperture through which a central single-particle beam passes in the field of the multitude of single-particle beams normally has no different shape than, for example, an otherwise elliptical field of apertures: In this context, the circle is merely a special form of the ellipse and fits mathematically precisely into the field distribution of the shapes or ellipses. It is not the case that this type of multi-aperture plate offers several free parameters for selecting the aperture.

[0026] An algorithmic approach to determining the size and shape of the respective apertures can be used, for example, to define two or more parameters to describe the aperture, which are then varied and optimized. Finally, the optimal apertures are determined for each individual particle beam, and the trajectory correction plate is thus completely designed. A fully designed trajectory correction plate can then ultimately comprise apertures of different sizes and shapes. However, it is also possible that only the size of the apertures within the trajectory correction plate actually varies because it has been determined that a variation in shape is not necessary. During the design process itself, however, the shape of the apertures in the plate was not predetermined from the outset. Instead, variation in shape was generally permitted.Ultimately, the shape depends on the operating parameter itself and its influence on trajectory deviations of the individual particle beams.

[0027] According to a preferred embodiment of the invention, when determining the shape of an aperture, the orientation of the shape within the trajectory correction plate is also determined. This is particularly practical for strictly geometric shapes, for example, when the orientation of a semi-major axis of an ellipse is specified.

[0028] According to a preferred embodiment of the invention, when determining the size of the respective aperture by means of a simulation, a relationship is determined between the size of the aperture and a resulting focus shift when a corrective voltage is applied to the trajectory correction plate; and / or when determining the shape of the respective aperture by means of a simulation, a relationship is determined between the shape of the aperture and a resulting changed beam profile when a corrective voltage is applied to the trajectory correction plate. Common particle-optical simulation programs can be used for the simulation. The changed beam profile describes, for example, the deviation of the beam profile from the ideal beam profile, for example a stigmatic beam profile.

[0029] According to a preferred embodiment of the invention, the determination of a relationship between the size of the aperture and a resulting focus shift is repeated upon application of at least one further correction voltage; and / or the determination of a relationship between the shape of the aperture and a resulting changed beam profile is repeated upon application of at least one further correction voltage. This allows the operating parameter interval to be selectively covered or traversed during a simulation. By applying a correction voltage, the correction for a specific operating parameter is always performed or simulated.

[0030] According to a preferred embodiment of the invention, the applied voltages cover or correct path deviations substantially across the entire operating parameter interval of the path correction plate associated with this operating parameter, wherein a best fit is determined for the aperture size at all applied correction voltages and a best fit is determined for the aperture shape for the single particle beam passing through this aperture. It is possible for the best fit to be determined simultaneously for both the aperture size and the aperture shape; ultimately, this depends on the mathematical or algorithmic implementation of the variations in a simulation program.

[0031] According to a preferred embodiment of the invention, the design of a trajectory correction plate involves optimizing the individual particle beam profiles toward a beam profile that is as stigmatic as possible after trajectory correction. This is the standard case. However, it is also possible, in principle, to select a different beam profile as the optimal beam profile. Ultimately, this depends on the experiment being conducted with the multi-beam particle beam system.

[0032] According to a preferred embodiment of the invention, one or more apertures in a trajectory correction plate have the shape of at least one of the following: circle, ellipse, shape with twofold symmetry, shape with threefold symmetry, shape with fourfold symmetry, shape with fivefold symmetry, shape with sixfold symmetry, shape with sevenfold symmetry, shape with eightfold symmetry. Shapes with generally n-fold symmetry are n-polygons with n ≥ 2 and n ∈ ℕ. These regular n-polygons can be rounded, since tips are disadvantageous when forming electrodes that ultimately represent the apertures. A shape with threefold symmetry can, for example, be an equilateral triangle with rounded corners; a shape with fourfold symmetry can, for example, be a square with rounded corners, etc.However, other forms with n-fold symmetry that are not n-gons are of course possible.

[0033] According to an embodiment of the invention, one or more apertures in a trajectory correction plate are in the form of a freeform. The aperture or apertures can thus also be shaped completely irregularly. What is decisive is that an aperture is designed exactly as it is optimal for the trajectory correction. The credo when designing the apertures in a trajectory correction plate is therefore: Find the apertures such that the corrections effected by them fit exactly to the present system.

[0034] According to a preferred embodiment of the invention, the operating parameters include such parameters, or the operating parameters consist of such parameters, that can be selected by a user of the multi-beam particle beam system for the operation of the multi-beam particle beam system. The user therefore has direct access to these parameters. Typically, these parameters are the parameters that the user sets to appropriately perform an experiment or measurement to be conducted by the user.

[0035] According to a preferred embodiment of the invention, the operating parameters comprise at least one parameter from the following list of parameters: beam current, landing energy, distance between the individual particle beams upon impact in an object plane, and angle of impact of the individual particle beams in an object plane (telecentricity). The beam current can be varied, for example, by adjusting a condenser lens system (fanning out the illuminating beam before impacting a multi-beam generator). Additionally or alternatively, a tip can be operated differently. Landing energy variation can be achieved, for example, by subjecting a sample holder to a variable voltage, thus generating a deceleration field for primary electrons or charged first individual particle beams, or an extraction field for secondary electrons or second individual particle beams.The distance between the individual particle beams upon impact in an object plane is linked to the system's magnification and can be varied, for example, by adjusting the objective lens and / or varying the working distance. The angle at which the individual particle beams impinge on an object plane can be varied or corrected, for example, by a corrector arranged in an intermediate image, if a telecentric impact of the individual particle beams is required. For many practical applications, a telecentric impact of the individual particle beams on a sample is advantageous.

[0036] According to an advantageous embodiment of the invention, the operating parameters include or consist of parameters that are component-related adjustment parameters. Preferably, the component-related adjustment parameters are not parameters that can be selected by a user of the multi-beam particle beam system for the operation of the multi-beam particle beam system.

[0037] According to a preferred embodiment of the invention, the control parameters comprise at least one parameter from the following list of parameters: beam splitter excitation, objective lens excitation, field lens excitation. The excitation can be a voltage and / or a current. This ultimately depends on the structural design of the particle optics. According to this embodiment of the invention, it is therefore possible to make corrections to trajectories on a component-specific basis. For example, there is then a trajectory correction plate for the beam splitter, a trajectory correction plate for the objective lens, and a trajectory correction plate for a field lens, etc.

[0038] According to a preferred embodiment of the invention, exactly one path correction plate is assigned to each operating parameter. This helps to keep the total number of path correction plates small.

[0039] According to a further preferred embodiment of the invention, the method further comprises the following step: minimizing the number of required trajectory correction plates. It is possible that all states of the multi-beam particle beam system can be mapped or corrected with fewer trajectory correction plates than those originally determined or designed. Minimizing the number of required trajectory correction plates is then de facto an orthogonalization of the trajectory correction plate system used. Whether this is possible, however, depends individually on the multi-beam particle beam system to be designed and, in particular, on how good a trajectory correction should or must be for a specific measurement or inspection.It may be possible to obtain a simplified system with fewer path correction plates through a clever combination and a certain tolerance in the residual error.

[0040] According to a preferred embodiment of the invention, the number of all operating parameters of the multi-beam particle beam system is greater than the number of all trajectory correction plates of the system. This can, for example, be an orthogonalized trajectory correction plate system.

[0041] According to a preferred embodiment of the invention, the method further comprises the following step: selecting a basic set of trajectory correction plates which provide a trajectory correction for all trajectory corrections to be expected in the system to be designed. In algorithmic terms, this is a multi-dimensional optimization. Those skilled in the art will know how such a process can be carried out in principle, for example using optimization methods and / or recursive methods, etc. Within the scope of the optimization, a further optimization goal can also be to minimize the total number of trajectory correction plates to be designed while maintaining a maximum permissible residual error tolerance. If an acceptable residual error is very small, more trajectory correction plates will tend to be required for the trajectory correction; if an acceptable residual error is somewhat larger, the trajectory correction may require fewer trajectory correction plates.with fewer path correction plates. Furthermore, by cleverly selecting the base as a linear combination of path corrections, it is possible to reduce the number of path correction plates required.

[0042] According to a second aspect of the invention, it relates to a computer program product with program code for executing the method as described above in various embodiments. The program code can be written in any programming language. The program code can be modular in structure. A module can, for example, access input and / or output parameters of a particle-optical simulation program.

[0043] According to a third aspect of the invention, it relates to a multi-beam particle beam system, in particular to a multi-beam particle microscope, which is designed using the method as described above in several embodiments. Typically, such a multi-beam particle beam system will have at least one trajectory correction plate with apertures that have both different sizes and different shapes. However, this is not necessary.

[0044] According to a fourth aspect of the invention, it relates to a multi-beam particle microscope having the following features: a multi-beam generator configured to generate a first field of a plurality of charged first single-particle beams; 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 impinge on the sample surface at impact locations that form a second field; 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 magnetic and / or electrostatic objective lens through which both the first and second single-particle beams pass; a beam switch arranged in the first particle-optical beam path between the multi-beam generator and the objective lens, and arranged in the second particle-optical beam path between the objective lens and the detection system; a plurality of trajectory correction plates, each having a plurality of apertures through which the plurality of first individual particle beams pass during operation and to which exactly one correction voltage associated with the trajectory correction plate is applied during operation; and a control, wherein apertures of different sizes and different shapes are arranged in at least one of the trajectory correction plates, and wherein the controller is configured to control the plurality of trajectory correction plates during operation with a correction voltage individually predefined for each trajectory correction plate, wherein the respective correction voltages are selected by the controller as a function of operating parameters for the multi-beam particle microscope.

[0045] 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 that the low-energy secondary electrons are 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.

[0046] The control system of the multi-beam particle microscope can be designed as a single or multi-part unit. For example, it is possible that the control system includes a special module for controlling the trajectory correction plates. However, this is not required.

[0047] According to a preferred embodiment of the invention, one of the trajectory correction plates is adapted to perform a trajectory correction based on a beam current or a beam current change. Such a trajectory correction plate thus corresponds to a beam current correction plate. If the beam current changes, the control of the trajectory correction plate changes.

[0048] Additionally or alternatively, one of the trajectory correction plates is adapted to perform a trajectory correction based on a landing energy or landing energy change. This corresponds to a landing energy correction plate.

[0049] Additionally or alternatively, a trajectory correction plate is adapted to perform a trajectory correction based on a distance or a change in distance of the first individual particle beams upon impingement of the first individual particle beams in the object plane. This trajectory correction plate thus corresponds to a distance correction plate.

[0050] Additionally or alternatively, one of the trajectory correction plates is adapted to perform a trajectory correction based on the angle or an angle change of the first individual particle beams upon impingement of the first individual particle beams in the object plane. This trajectory correction plate thus corresponds to a telecentricity correction plate.

[0051] The trajectory correction plates mentioned as examples in this embodiment are typical trajectory correction plates of operating parameters that can be actively selected by a user of the multi-beam particle microscope for the operation of the multi-beam particle microscope.

[0052] According to a further preferred embodiment of the invention, one of the trajectory correction plates is adapted to perform a trajectory correction based on an excitation or excitation change of the objective lens. This trajectory correction plate thus corresponds to an objective lens correction plate.

[0053] Additionally or alternatively, one of the trajectory correction plates is adapted to perform a trajectory correction based on an excitation or excitation change of the beam switch. Such a trajectory correction plate corresponds to a beam switch correction plate.

[0054] Additionally or alternatively, one of the trajectory correction plates is adapted to perform a trajectory correction based on an excitation or excitation change of a field lens arranged in the first particle-optical beam path. Such a trajectory correction plate corresponds to a field lens correction plate.

[0055] The trajectory correction plates described in this embodiment are typical examples of component-specific trajectory correction plates. However, the component-specific nature does not specify the specific arrangement of the trajectory correction plates in the particle-optical beam path. Rather, what is crucial is the type of trajectory correction that must be performed using the corresponding trajectory correction plate, based on the type of aberration correction. The arrangement of the corresponding trajectory correction plates in the beam path depends on this.

[0056] According to a preferred embodiment of the invention, the multi-beam generator comprises at least one trajectory correction plate; and / or a trajectory correction plate is arranged in the region of an intermediate image plane.

[0057] The multi-beam generator can in any case comprise a stack of multi-aperture plates, which, on the one hand, generate the plurality of initial single-particle beams in the first place and, on the other hand, also perform initial corrections to the individual particle beams. For example, the focus stroke or the field curvature can be pre-corrected, as can field astigmatism. Alternatively or additionally, the trajectory correction plates according to the invention can be provided in the multi-beam generator. It is important that the plurality of individual particle beams are strictly separated from one another in the area of ​​the multi-beam generator. Nevertheless, the beam waist of the individual particle beams in the area of ​​the multi-beam generator is not minimal, but has a certain extent. Trajectory correction plates arranged in the area of ​​the multi-beam generator can then, in principle, compensate for any field dependence of an aberration.

[0058] If a trajectory correction plate is positioned in the area of ​​an intermediate image plane, the beam diameter of the individual particle beams is minimal there. At such a location, only the angle of each individual particle beam can be individually influenced using a trajectory correction plate. A telecentricity correction plate could therefore be positioned, for example, in the area of ​​an intermediate image.

[0059] According to a preferred embodiment of the invention, a multi-aperture plate with a plurality of round apertures is arranged directly before and after a trajectory correction plate, with the same voltage, in particular ground potential, applied to both multi-aperture plates. This allows for better separation of the field patterns generated by the trajectory correction plates. For example, it is possible to provide an alternating sequence of trajectory correction plates on the one hand and grounded multi-aperture plates on the other hand in the multi-beam generator. This arrangement is particularly simple in design.

[0060] According to a further embodiment of the invention, the multi-beam particle microscope further comprises means for in-situ plasma cleaning of the trajectory correction plates; and / or the multi-beam particle microscope comprises means for providing a low partial pressure of hydrogen gas during operation of the multi-beam particle microscope for cleaning purposes. The hydrogen can be provided continuously during operation of the multi-beam particle microscope, or it can be provided in pulsed form or intermittently between different images or generally during an interruption of an image acquisition or interruption of a scanning process. Additionally or alternatively, the multi-beam particle microscope can have means for continuously heating the trajectory correction plates. This heating contributes to the cleaning of the trajectory correction plates.Cleaning the trajectory correction plates is beneficial for the correct functioning of the trajectory correction plates and for precise correction of the trajectories, since contamination or deposits on the apertures in the trajectory correction plates can impair the high-precision correction.

[0061] According to a preferred embodiment of the multi-beam particle microscope, in addition to or as an alternative to the trajectory correction plates in the first particle-optical beam path, the multi-beam particle microscope has at least one further trajectory correction plate in the second particle-optical beam path, wherein the further trajectory correction plate has a plurality of apertures through which the plurality of second individual particle beams pass during operation and to which exactly one correction voltage associated with the further trajectory correction plate is applied during operation, wherein apertures of different sizes and different shapes are arranged in the at least one path correction plate, and wherein the controller is configured to control the trajectory correction plate during operation with a further correction voltage individually predefined for the further trajectory correction plate, wherein the further correction voltage is selected by the controller as a function of an operating parameter for the multi-beam particle microscope.

[0062] The apertures in the further trajectory correction plate in the second particle-optical beam path can be designed analogously to the method described above for designing the multi-beam particle beam system with monolithic trajectory correction plates in the first particle-optical beam path.

[0063] It is possible to combine the above-described embodiments of the invention in whole or in part within one aspect of the invention and across aspects, provided that this does not result in any technical contradictions.

[0064] The invention will be better understood with reference to the accompanying figures, in which: Fig. 1: shows schematically a multi-beam particle microscope; Fig. 2: shows several monolithic multi-aperture plates with openings of the same shape Fig. 3: schematically illustrates apertures of different shapes; Fig. 4: illustrates a flow chart of a method according to the invention for designing a multi-beam particle beam system; Fig. 5: shows schematically a path correction plate for a beam switch; Fig. 6: shows schematically a path correction plate for an objective lens; Fig. 7: shows schematically an alternative trajectory correction plate for an objective lens; Fig. 8: shows schematically a trajectory correction plate with threefold apertures of different shapes; Fig. 9: shows schematically a trajectory correction plate with fourfold apertures of different shapes; Fig. 10: shows schematically a trajectory correction plate with freeform apertures; Fig. 11: schematically illustrates the ratio S of single beam diameter to beam bundle diameter; Fig. 12: shows schematically a multi-beam particle microscope with trajectory correction plates, which is designed according to the method of the invention; Fig. 13: shows schematically a multi-beam generator with monolithic trajectory correction plates; Fig. 14: schematically shows a multi-beam generator with monolithic path correction plates

[0065] Fig. 1 schematically shows a multi-beam particle microscope 1. The multi-beam particle microscope 1 has a beam generation device 300 with a particle source 301, for example, an electron source. A diverging particle beam 309 is collimated by a sequence of condenser lenses 303.1 and 303.2 and impinges on a multi-aperture arrangement 305. The multi-aperture arrangement 305 comprises several multi-aperture plates 306 and a field lens 308. The multi-aperture arrangement generates a plurality of individual particle beams 3 or individual electron beams 3. Center points of apertures of the multi-aperture plate arrangement are arranged in a field, which is imaged onto another field formed by beam spots 5 in the object plane 101. The distance between centers of apertures of a multi-aperture plate 306 can be, for example, 5 µm, 100 µm and 200 µm.The diameters D of the apertures are smaller than the distance between the centers of the apertures; examples of diameters are 0.2 times, 0.4 times, and 0.8 times the distance between the centers of the apertures.

[0066] The multi-aperture arrangement 305 and the field lens 308 are configured to generate a plurality of focal points 323 of primary beams 3 in a grid arrangement on a surface 321. The surface 321 does not have to be a flat surface, but can be a spherically curved surface to accommodate field curvature of the subsequent particle-optical system.

[0067] The multi-beam particle microscope 1 further comprises a system of electromagnetic lenses 103 and an objective lens 102, which image the beam foci 323 from the intermediate image area 325 into the object plane 101 in a reduced size. The first individual particle beams 3 pass through the beam switch 400 and a collective beam deflection system 500, with which the plurality of first individual particle beams 3 are deflected during operation and the image field is scanned. The first individual particle beams 3 impinging on the object plane 101 form, for example, a substantially regular field, wherein distances between adjacent impingement points 5 can be, for example, 1 µm, 10 µm, or 40 µm. The field formed by the impingement points 5 can, for example, have a rectangular or hexagonal symmetry.

[0068] The object 7 to be examined can be of any type, for example, a semiconductor wafer or a biological sample, and it can comprise an array of miniaturized elements or the like. The surface 15 of the object 7 is arranged in the object plane 101 of the objective lens 102. The objective lens 102 can comprise one or more electron-optical lenses. It can be, for example, a magnetic objective lens and / or an electrostatic objective lens.

[0069] The primary particles 3 striking the object 7 generate interaction products such as secondary electrons, backscattered electrons, or primary particles that have experienced a reversal of motion for other reasons, which emanate from the surface of the object 7 or from the first plane 101 or object plane 101. The interaction products emanating from the surface 15 of the object 7 are formed into secondary particle beams 9 by the objective lens 102. The secondary beams 9 pass through the beam switch 400 after the objective lens 102 and are fed to a projection system 200. The projection system 200 has an imaging system 205 with projection lenses 208, 209 and 210, a contrast aperture 214 and a multi-particle detector 207. Impact locations 25 of the second single-particle beams 9 on detection areas of the multi-particle detector 207 lie in a third field with a regular distance from one another.Example values ​​are 10 µm, 100 µm and 200 µm.

[0070] The multi-beam particle microscope 1 further comprises a computer system or a control unit 10, which in turn can be designed as a single part or in multiple parts, and which is designed both to control the individual particle-optical components of the multi-beam particle microscope 1 and to evaluate and analyze the signals obtained with the multi-detector 207 or the detection unit.

[0071] Further information on such multi-beam particle beam systems or multi-beam particle microscopes 1 and components used therein, such as particle sources, multi-aperture plates and lenses, can be obtained from the international patent applications WO 2005 / 024 881 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 its entirety by reference into the present application.

[0072] In the illustrated multi-beam particle microscope 1, imaging errors generally occur due to the use of particle-optical components. For this reason, the electron optics or, more generally, the optics for charged particles of the multi-beam particle microscope 1 are optimized. However, due to the Scherzer theorem, these measures have a limit that is no longer sufficient for today's requirements for beam uniformity. The illustrated multi-beam particle microscope 1 can therefore comprise one or more correction means. These correction means include, for example, already known monolithic multi-aperture plates with apertures of a predetermined shape, but of different sizes along the field path. Additionally or alternatively, the inventive trajectory correction plates 350 (not shown in Figure 1) can also be arranged as correction means at various positions in the particle-optical beam path in the multi-beam particle microscope 1.These path correction plates 350 are designed according to the method of the invention. This will be discussed in more detail later.

[0073] Fig. 2 schematically shows several monolithic multi-aperture plates 350 with openings 351. The openings 351 in the respective plate 350 basically have the same shape: In the example according to Fig. 2a) shows a monolithic multi-aperture plate 350 whose apertures 351 are all circular. However, the size of the apertures 351 varies depending on the position of the respective aperture 351 in the field of apertures 351. In the example shown, the diameter of the apertures 351 increases with the radial distance r from a center point C in the monolithic multi-aperture plate 350. Thus, there is a radial dependence of the aperture size; it varies as a function of r. The dependence on r can be different, e.g., linear, quadratic, cubic, hyperbolic, etc.

[0074] Fig. 2b) shows a monolithic multi-aperture plate 350 with circular apertures 351 that exhibit a Cartesian variation of the diameter along the Cartesian coordinate x. The diameters of the apertures 351 do not vary in the direction of the Cartesian coordinate y. With such a multi-aperture plate 350, it is possible, for example, to correct an image field tilt. Of course, it is also possible to imprint a variation of the aperture diameters in the y direction into a multi-aperture plate 350 and not provide any variation of the aperture diameters along the x coordinate. It is also possible to implement a variation in both the x-direction and the y-direction (i.e., obliquely) in a multi-aperture plate 350.

[0075] Fig. 2c) shows a monolithic multi-aperture plate 350 with elliptical apertures 351 (the aperture positioned centrally in the plate 350 around the center point C is only a special case of the ellipse, not a different shape). The longitudinal axis I of the elliptical apertures 351 increases with the distance from the center point C. Such a monolithic multi-aperture plate 350 can be used to correct field astigmatism. The orientation of the longitudinal axis I relative to the center point 358 is then transverse to an orientation of the longitudinal axis of astigmatic beam spots upon incidence in an object plane (not shown). In the example shown, the orientation of the longitudinal axis I is variable within the field of apertures in Cartesian coordinates; at the same time, however, its orientation is fixed, namely in the radial direction from the center point C.The orientation here is therefore not a freely selectable parameter, but occurs along a given, uniform direction.

[0076] For all Fig. In the monolithic multi-aperture plates 350 shown in Figure 2, the shape of the apertures 351 is fixed. Only a single (true) parameter is varied in the field of apertures, namely the aperture size. The present invention dispenses with the specification of the aperture shape in order to obtain more free parameters for aberration corrections, even if only a single correction voltage is applied to a monolithic multi-aperture plate 350. In order to design a monolithic multi-aperture plate or trajectory correction plate 350, according to the invention, not only the size of the aperture 351 in a plate 350 is varied, but also the respective shape of the apertures 351 is varied. Within the scope of the design process, there are therefore at least two free parameters for each aperture 351 in the monolithic multi-aperture plate 350 and not just a single parameter.

[0077] Fig. Figure 3 schematically illustrates apertures 351 of various shapes. Shown in each case is the outer edge of an aperture 351, which is at a constant potential by applying a voltage to the multi-aperture plate 350. Additionally, equipotential lines 353 of the electrostatic field inside the apertures 351 are shown in dashed lines in a suitable section plane perpendicular to the particle beam.

[0078] Specifically, Fig. 3a) a circular aperture 351 with circular equipotential lines 353, which form a circular perpendicular to the field lines. If a single particle beam 3 passes centrally through the aperture 351, the particle beam 3 experiences a lensing effect. If the passage occurs off-axis, a deflection by a certain angle is added to the lensing effect.

[0079] In Fig. 3b), the aperture 351 shown is elliptical. The equipotential lines 353 are also elliptical and perpendicular to the field lines. This allows astigmatism to be created or corrected.

[0080] Fig. 3c) shows an aperture 351 whose shape corresponds to a rounded triangle, for example, a rounded equilateral triangle. The equipotential lines 353 have the same shape. When a single-particle beam 3 passes through the aperture with 3-fold symmetry, a three-wave pattern of the single-particle beam profile can be generated, or an existing three-wave pattern can be corrected.

[0081] In principle, any shape is possible for an aperture of 351, as long as it is suitable for correcting any aberrations that occur.

[0082] Fig. 4 illustrates, as a flowchart, an example of a method according to the invention for designing a multi-beam particle beam system, in particular a multi-beam particle microscope 1. In a first method step S0, the multi-beam particle beam system, in particular a multi-beam particle microscope 1, is provided. For this purpose, it can actually be physically provided, i.e., already manufactured. However, it is also possible for the multi-beam particle beam system 1 to exist only as a simulation. The multi-beam particle beam system or multi-beam particle microscope 1 operates with a plurality of charged individual particle beams 3 and images them into an object plane 101.For aberration correction, the multi-beam particle beam system 1 has a plurality of trajectory correction plates 350, each of the trajectory correction plates 350 having a plurality of apertures 351 for the plurality of individual particle beams 3. During operation of the multi-beam particle beam system 1, precisely one adjustable correction voltage is applied to each of the trajectory correction plates 350 to generate a contribution to the trajectory correction. The number of apertures 351 per trajectory correction plate 350 is matched to the number of individual particle beams 3 of the multi-beam particle beam system 1 to be designed; thus, each individual particle beam 3 passes through an aperture 351 assigned to it and only to it.

[0083] In a further method step S1, operating parameters are defined that describe an operating state of the multi-beam particle beam system 1. In particular, those operating parameters are selected whose changes influence trajectory deviations of the individual particle beams 3 from the ideal particle beam trajectories. Operating parameters can be, for example, the beam current, the landing energy, and the beam spacing of the individual particle beams. However, it is also possible for the operating parameters to include or consist of parameters that are component-specific control parameters. Such parameters can be, for example, beam switch excitation, objective lens excitation, field lens excitation, etc.

[0084] In method step S2, operating parameter intervals are defined for each operating parameter, within which possible values ​​of the respective operating parameter lie during operation of the multi-beam particle beam system 1. For example, the interval within which the beam current or landing energy can be varied is defined. The definition of these operating parameter intervals serves to define in which phase space of the multi-beam particle beam system 1 a correction of aberrations must be performed. The aberrations depend on the operating parameters.

[0085] In a method step S3, a single-particle beam trajectory deviation from an ideal single-particle beam trajectory is determined for each operating parameter along its operating parameter interval for each of the individual particle beams 3. This trajectory deviation can be determined, for example, by a corresponding particle-optical simulation. However, it is also possible for corresponding measurements to be performed on the already existing multi-beam particle beam system 1. For example, the beam profile and / or the position and shape of the minimum beam waist can be measured in the object plane. The trajectory correction plates 350, which are still to be designed, will then be added to or implemented in the system later.

[0086] In method step S4, the trajectory correction plates 350 are then designed. According to the invention, a trajectory correction plate 350 is assigned to each operating parameter. For each trajectory correction plate 350, the sizes of its apertures 351 are determined based on the respectively determined trajectory deviations of the associated individual particle beams 3 along the operating parameter interval. In addition, for each trajectory correction plate 350, the shapes of the respective apertures 351 are determined based on the respectively determined trajectory deviations of the associated individual particle beams 3 along the operating parameter interval. The determination of the sizes and shapes of the respective apertures can take place in two separate method steps or in a combined method step. This fundamentally depends on the type of mathematical implementation of the design method.In any case, however, it is crucial that, in this design of the multi-aperture plates 350, at least two free parameters, such as shape and size, are selected or optimized for each aperture. An aperture of a specific shape and size is then designed such that a path correction is as optimal as possible for each value of the operating parameter to which a specific correction voltage is assigned.

[0087] It is pointed out again that according to the invention, a kind of change of basis takes place: Instead of providing a single multi-aperture plate or a sequence of multi-aperture plates for correcting a specific category or type of aberration (field curvature or astigmatism correction or image plane tilt, etc.), according to the invention, the monolithic multi-aperture plates or path correction plates 350 for correcting aberrations are designed to be tailored to changes in specific operating parameters. The corresponding explanations in the general part of the description of the invention are explicitly referred to again at this point.

[0088] Fig. Figure 5 schematically shows a trajectory correction plate 350 for a beam splitter 400. In the design of this trajectory correction plate 350, the apertures 351 were varied in shape and size. The result is a trajectory correction plate 350 with apertures of varying ellipticity 351; strictly mathematically, the apertures can also be non-elliptical. Fig. 5, a field distribution of the apertures 351 can be seen: A central aperture 351 around the center point C is circular and relatively small, while the remaining apertures 351 tend to be larger. If one draws a longitudinal axis into the oval shapes of the apertures 351, one recognizes very different orientations of these longitudinal axes. The orientation of these axes alone is a clear difference from the already known uniform orientation of longitudinal axes for pure astigmatism correction (cf. Fig. 2c).

[0089] Fig. Figure 6 schematically shows a trajectory correction plate 350 for a magnetic objective lens 102. When designing this trajectory correction plate 350, both the size and shape of the aperture 351 were also freely selectable or optimized. In the example shown, the apertures 351 are essentially elliptical, which is due to the fact that the objective lens 102 causes, among other things, field astigmatism as an aberration when its adjustment parameter or excitation changes. However, this could also be different.

[0090] Fig. 7 shows a trajectory correction plate 350 for an objective lens 102, which causes two leading aberrations, namely field curvature and field astigmatism, upon excitation change. The multi-aperture plate 350 designed according to the inventive method essentially comprises elliptical apertures 351, which essentially correspond to a superposition of ellipses and circular apertures 351. This example clearly shows that it is not absolutely necessary to correct each category of aberrations with a separate monolithic multi-aperture plate and thus to use a plurality of correction plates. Instead, it is also possible to achieve complete aberration correction upon a change in a specific control parameter, here the excitation of an objective lens 102, by appropriately designing the apertures 351 in a single trajectory correction plate 350.With such an approach, it is particularly important that the shapes of the apertures are not fixed in the design of the path correction plate 350, but can be variably determined.

[0091] Fig. Figure 8 schematically shows a trajectory correction plate 350 with 3-fold apertures of various shapes. Different 3-fold shapes can, for example, generate hexapoles or correct hexapole components in aberrations. Here, too, the orientation and hexapole strength vary with position.

[0092] Fig. Figure 9 schematically shows a trajectory correction plate 350 with 4-fold apertures 351 of various shapes. These shapes are essentially more or less rounded squares. Such apertures 351 can generate eight-poles when a voltage is applied to the trajectory correction plate 350 and correct components of 4-fold aberrations.

[0093] Fig. 10 schematically shows a trajectory correction plate 350 with free-form apertures 351. This example of a trajectory correction plate 350 is the logical consequence of a completely free optimization of the shapes of apertures 351. Theoretically, it is possible for an aperture 351 to be designed in any desired manner; what is crucial is that the aperture 351 is actually suitable for correcting trajectory deviations of the single particle beam 3 passing through it. This correction is performed not only for a specific value of an operating parameter, but along the entire operating parameter interval (pointwise or continuously). A correction voltage is always assigned to the value of the respective operating parameter, which is applied to the monolithic multi-aperture plate 350.

[0094] Fig. 11 schematically illustrates the ratio S of individual beam diameter to beam bundle diameter. This ratio provides information about whether the multitude of individual particle beams in the particle-optical beam path are strictly separated from one another or whether the individual particle beams 3 overlap with one another. This is crucial for determining whether an individual trajectory correction can be carried out for each individual particle beam 3 or whether only a global trajectory correction can be carried out for all individual particle beams 3 together. In the latter case, however, it is still the case that with a global lens or global electrode at least a weaker field-dependent change in the individual particle beams is possible. In practice, however, an aberration to be corrected with a global trajectory corrector will at least essentially be field-independent.

[0095] At a ratio S = 0, the diameter of each individual particle beam 3 is much smaller than the beam diameter of the entire beam bundle in Fig. 11 as a hexagonal arrangement of seven individual particle beams 3. The ratio S = 0 is realized in a multi-beam particle beam system 1 in an intermediate image position. The individual particle beams 3 are therefore very clearly separated from one another, so that an individual beam correction or trajectory correction can be carried out at this position. At such a location, for example, a trajectory correction plate with a plurality of apertures for each of the individual particle beams 3 can be arranged. However, exactly in the intermediate image position, only the angle of each individual particle beam 3 can be influenced by means of the trajectory correction plate 350, to which a predefined correction voltage is applied, but not the position of the individual particle beams 3. In the intermediate image, for example, a telecentric trajectory correction plate 350 can be arranged.

[0096] At a ratio S = 0.1 of individual beam diameter to beam bundle diameter, the first individual particle beams 3 are still strictly separated from one another, and the diameter of each individual particle beam 3 is expanded. This situation exists, for example, in the area of ​​the multi-beam particle generator 305 of a multi-beam particle beam system 1 or multi-beam particle microscope 1. A trajectory correction plate 350 can therefore, for example, be integrated into the multi-beam particle generator 305. With a trajectory correction plate 350 at a position according to S = 0.1, any field dependence of aberrations can, in principle, be individually corrected for each of the individual particle beams 3.

[0097] At a ratio S = 0.3 of individual beam diameter to beam bundle diameter, the individual particle beams 3 are no longer strictly separated from one another, which is why a trajectory correction plate 350 with individual apertures for each individual particle beam cannot be meaningfully arranged at such a position in the particle-optical beam path. A relationship S = 0.3 is present, for example, near an image field plane.

[0098] Fig. 12 schematically shows a multi-beam particle microscope 1 with trajectory correction plates, which is designed according to the method according to the invention. In the example shown, trajectory correction plates are integrated into the multi-beam particle generator 305. The multi-beam particle generator 305 has a plurality of multi-aperture plates. These can serve both to generate the plurality of individual particle beams 3 and for the first beam shaping. Additionally or alternatively, the trajectory correction plates 350 according to the present invention can be arranged in the multi-beam generator 305.

[0099] An example is Fig. 12 shows a plurality of multi-aperture plates 306.1, 306.2, 306.3, and 306.4. The multi-beam particle generator 305 can, of course, have even more multi-aperture plates. In the example shown, at least two of the multi-aperture plates 306.1 to 306.4 are trajectory correction plates 350 according to the present invention, whose plurality of apertures 351 are penetrated by the plurality of first individual particle beams 3 during operation, and to which, during operation, exactly one correction voltage associated with the trajectory correction plate 350 is applied. Apertures 351 of different sizes and shapes are arranged in at least one trajectory correction plate, or, in the course of the design process of the multi-beam particle microscope 1, the apertures 351 have been optimized or determined by at least two free parameters, corresponding, for example, to a size and a shape.The trajectory correction plates 350 are controlled by the controller 10 during operation with a correction voltage that is individually predefined for the respective trajectory correction plate 350, wherein the respective correction voltage is selected by the controller 10 as a function of the respective value of the operating parameter for the multi-beam particle microscope 1.

[0100] It is possible, for example, for one of the trajectory correction plates, e.g., trajectory correction plate 306.4, to be adapted to perform a trajectory correction based on a beam current or a beam current change. Additionally or alternatively, it is possible, for example, for trajectory correction plate 306.3 to be adapted to perform a trajectory correction based on a landing energy or a change in the landing energy. Additionally or alternatively, it is possible, for example, for trajectory correction plate 306.2 to be adapted to perform a trajectory correction based on a distance or a distance change of the first individual particle beams upon impact of the first individual particle beams 3 in the object plane 101 (pitch change).

[0101] Additionally or alternatively, the multi-beam generator 305 can have one or more further trajectory correction plates 350. For example, it is possible to provide a trajectory correction plate 350 to perform a trajectory correction based on an excitation or a change in excitation of the object lens 102. Additionally or alternatively, one of the trajectory correction plates 350 can be adapted to perform a trajectory correction based on an excitation or a change in excitation of the beam splitter 400. Additionally or alternatively, one of the trajectory correction plates can be adapted to perform a trajectory correction based on an excitation or a change in excitation of a field lens arranged in the first particle-optical beam path 13. This field lens can be, for example, one of the field lenses 307, 308, or 103.The shape of the apertures in the trajectory correction plates 350 may also be a useful combination of the above shapes and shape gradients, which, for example, minimizes the number of correction plates 350 required.

[0102] According to one example, a multi-aperture plate with a plurality of round apertures is arranged directly before and after a path correction plate 350, wherein the same voltage, in particular ground potential, is applied to both multi-aperture plates. In this way, a single lens or a system comprising several single lenses can be realized. The provision of the multi-aperture plates, which are in particular grounded, also between two path correction plates contributes to separating fields or field patterns caused by the path correction plates from one another.

[0103] According to an exemplary embodiment of the invention, the multi-beam particle microscope 1 comprises a voltage source 503 configured to adjust the landing energy of the first individual particle beams 3 by changing the deceleration field near a sample surface or wafer surface arranged in the object plane 101. Due to the changed landing energy, the focus position of the first individual particle beams 3 also changes upon impact in the object plane 101. This can be corrected very precisely using a trajectory correction plate 350, which is precisely designed for landing energy correction. The apertures 351 most suitable for this purpose can be ideally designed according to their size and shape. In many cases, such a landing energy correction plate has relatively round apertures whose diameter varies linearly with the distance from the central beam or a plate center point.

[0104] Additionally or alternatively, it is possible for a spherical component of a trajectory to be corrected, for example, caused by a change in the refractive power of any lens in the first particle-optical beam path. This lens can, in turn, be assigned a special lens correction plate 350 for correcting the trajectory. Here, too, it is possible to optimally design the apertures 351 of this lens correction plate 350 for the specific multi-beam particle microscope 1, and not just specify, for example, a quadratic dependence of aperture diameters for the lens correction plate. However, this can, of course, be the case in principle.

[0105] In the Fig. In the example shown in Figure 12, a trajectory correction plate 390 is further provided in the region of the intermediate image or along the curved intermediate image plane 321, which can perform a trajectory correction based on an angle or an angle change of the first individual particle beams 3 when the first individual particle beams 3 impinge on the object plane 101. The trajectory correction plate 390 is thus, for example, the aforementioned telecentricity correction plate 390. Its voltage supply is in turn controlled by the controller 10, depending on the selected operating parameter, here the telecentricity or the angle.

[0106] Fig. Figure 13 schematically shows a multi-beam generator 305 with monolithic trajectory correction plates 306.2, 306.3, and 306.4. A voltage V1, V2, and V3, respectively, is applied to these trajectory correction plates 306.2, 306.3, and 306.4. The value of these correction voltages V1, V2, and V3 depends on the operating parameters and their current values ​​assigned to the respective trajectory correction plates 306.2, 306.3, and 306.4. The operating parameters and the associated correction voltages V1, V2, and V3 are provided or set by the controller 10 of the multi-beam particle microscope 1.

[0107] Fig. 13 further shows in particular the integration of the inventive trajectory correction plates 306.2, 306.3 and 306.4 into already existing multi-beam generators 305. In the illustrated example, the multi-beam generator 305 comprises in the z-direction, which corresponds to the propagation direction of the individual particle beams 3, a sequence with six multi-aperture plates 304, 306.1, 306.2, 306.3, 306.4 and 310 as well as a global condenser lens 307. Each of the multi-aperture plates 304, 306.1 to 306.4 and 310 comprises a plurality of apertures 351, through which the plurality of individual particle beams 3 pass. The cross section through the apertures 351 in Fig. 13 is not to scale; instead, the illustration is in Fig. 13 about the fundamentally possible arrangement of path correction plates 350 in the form of the multi-aperture plates 306.2, 306.3, and 306.4 in a multi-beam generator 305.

[0108] The plurality of multi-aperture plates 304, 306.1, 306.2, 306.3, 306.4, and 310 are spaced apart from one another by spacers 83.1 to 83.5. Furthermore, a spacer 86 is provided between the final multi-aperture plate 310 and the global lens electrode 307. The plurality of first individual particle beams 3 are generated by the impact of a collimated particle or electron beam 309 upon passing through the first multi-aperture plate 304, which is also called a filter plate or pre-aperture plate. The pre-aperture plate 304 includes a metallic layer 99 on its beam input side for stopping and absorbing the electrons of the electron beam 309 impinging thereon around the plurality of apertures 85. In the example shown, the material of the pre-aperture plate 304 is made of a conductive material, e.g. doped silicon, and is at ground potential.

[0109] The next multi-aperture plate is in the example shown in Fig. 13 a multi-stigmator plate 306.1. The multi-stigmator plate 306.1 comprises a plurality of four or more electrodes 82, e.g., eight electrodes for each of the apertures. During operation of the multi-beam particle microscope 1, different voltages, for example in the range between -20 V and +20 V, can be applied to each of these electrodes, thereby individually influencing each individual particle beam 3. For example, it is possible to deflect each individual particle beam 3 in any direction up to a few µm using an antisymmetric voltage difference in order to pre-correct a distortion correction of the illuminating unit 100. An astigmatism pre-correction of each individual particle beam 3 can be performed in this way. With an offset voltage, each multipole element can additionally function as an individual lens.

[0110] The multi-aperture plates 306.2, 306.3, and 306.4, which implement trajectory correction plates 350 in the illustrated example, can in principle be any trajectory correction plates 350. For example, it is possible for the trajectory correction plate 306.2 to correspond to a landing energy correction plate, the multi-aperture plates 306.3 to a beam current correction plate, and the multi-aperture plate 306.4 to correspond to a distance correction plate or pitch correction plate. However, it is also possible for additional trajectory correction plates 350 to be provided. Alternatively, the multi-aperture plates 306.2, 306.3, and 306.4 can be, for example, an objective lens correction plate, a beam switch correction plate, and a field lens correction plate. Furthermore, what has already been stated in the general description of the invention applies.

[0111] The multi-aperture plate 310 is a two-layer multi-aperture plate and includes a plurality of ring electrodes 79 for the plurality of apertures, each ring electrode configured to individually change or correct a focal position of the first single-particle beam 3 passing through it. The upper layer is insulated from the layer or layer with the ring electrodes 79 and is made of a conductive material such as doped silicon.

[0112] The field lens 307 comprises a ring electrode 84, to which a high voltage of, for example, 3 kV to 20 kV, e.g., 12 kV to 17 kV, can be applied. In the example shown, the condenser lens 307 provides a global electrostatic lens field for global focusing of the plurality of individual particle beams 3.

[0113] Fig. Figure 14 shows a schematic section of a multi-beam generator 305 with monolithic trajectory correction plates. In contrast to Fig. 13, a grounded multi-aperture plate 311.1 to 311.4 with a plurality of round apertures 351 is provided between the path correction plates 306.2, 306.3, and 306.4, or directly before or after them. This facilitates the separation of the individual corrections or correction fields from one another. Other integrations or arrangements in the multi-beam generator 305, both with regard to the number and sequence of multi-aperture plates, are of course possible.

[0114] According to a further embodiment of the invention, the multi-beam particle microscope 1 further comprises means for in-situ plasma cleaning of the trajectory correction plates 350; and / or the multi-beam particle microscope 1 comprises means for providing a low partial pressure of hydrogen gas during operation of the multi-beam particle microscope 1 for cleaning purposes. The hydrogen can be provided continuously during operation of the multi-beam particle microscope 1, or it can be provided in pulsed form or intermittently between different images or generally during an interruption of an image acquisition or interruption of a scanning process. The means for in-situ plasma cleaning and / or the means for providing hydrogen can be arranged in the region of the multi-beam generator 305 (in the Fig. 13 and Fig. 14 not explicitly shown). Additionally or alternatively, the multi-beam particle microscope 1 can have means for continuously heating the trajectory correction plates 350. The heating contributes to the cleaning of the trajectory correction plates 350. Cleaning the trajectory correction plates 350 is advantageous for correct functioning of the trajectory correction plates or for precise correction of the trajectories, since contamination or deposits on the apertures 351 in the trajectory correction plates 350 can impair the high-precision correction. For example, it is possible to heat the trajectory correction plates 306.2, 306.3 and 306.4, which are shown in the Fig. 13 and Fig. 14 (the heating means are shown in the Fig. 13 and Fig.14 not explicitly shown). In addition, the grounded multi-aperture plates 311.1 to 311.4, which are provided with a plurality of round apertures 351, or other multi-aperture plates of the multi-beam generator can also be heated.

[0115] Overall, it can be noted that according to the present invention, a very comprehensive, precise, and customized trajectory correction for the plurality of individual particle beams 3 can be performed with a very small number of trajectory correction plates 350. These trajectory corrections can also be applied analogously to the secondary beam path.

[0116] Disclosed is a method for designing a multi-beam particle microscope 1 and a multi-beam particle microscope 1 which operates with a plurality of charged single-particle beams 3 and projects these onto an object plane 101 and which has a plurality of trajectory correction plates 350. Each of the trajectory correction plates 350 has a plurality of apertures 351 for the plurality of single-particle beams 3, and in operation of the multi-beam particle microscope 1, exactly one adjustable correction voltage is applied to each of the trajectory correction plates 350. A trajectory correction plate 350 is fixedly assigned to an operating parameter of the multi-beam particle microscope 1. When designing the trajectory correction plates, the apertures 351 in the trajectory correction plates 350 are adapted in terms of shape and size such that trajectory deviations related to operating parameters of all single-particle beams 3 can be corrected. List of reference symbols 1 multi-beam particle microscope 3 primary particle beams, first single particle beams 5 beam spots, impact points 7 Object, sample, wafer 9 secondary particle beams, second single particle beams 10 Computer system, control 15 Sample surface, wafer surface 25 pixels of a second single particle beam 81 Multipole electrode 82 Ring electrode 83 spacers 84 Ring electrode 85 aperture 86 spacers 99 Absorbing and conductive layer 101 Object level 102 objective lens 103 Field lens 105 Axis 108 Pupillary plane 200 detector system 205 Projection lens system 206 Projection lens 207 Multi-particle detector 208 Projection lens 209 Projection lens 210 projection lens 212 Beam crossing, cross-over 214 aperture filter, contrast diaphragm 220 multi-aperture corrector, single deflector array 222 Collective anti-deflection system 300 beam generating device 301 particle source 303 Collimating lens system 304 multi-aperture array, filter plate 305 multi-aperture array, multi-beam particle generator 306 Microoptics with multi-aperture plates 307 field lens 308 field lens 309 diverging particle beam 310 multi-aperture plate 311 grounded multi-aperture plate with round apertures 321 Intermediate image plane 323 beam foci 333 Holding area 335 membrane area 350 monolithic multi-aperture plate, trajectory correction plate 351 aperture 390 Telecentric correction plate 400 beam switch, magnet arrangement 500 scan deflectors 503 Voltage source 600 Moving table or positioning device 701 global trajectory corrector (near pupil) 703 global trajectory corrector (between field and pupil) A axis C Center r radial direction x direction y direction z direction l Longitudinal axis S Ratio of single beam diameter to beam bundle diameter

Claims

[1] A method for designing a multi-beam particle beam system (1) which operates with a plurality of charged individual particle beams (3) and images them into an object plane (101) and which has a plurality of trajectory correction plates (350), each of the trajectory correction plates (350) having a plurality of apertures (351) for the plurality of individual particle beams (3), and wherein, during operation of the multi-beam particle beam system (1), precisely one adjustable correction voltage is applied to each of the trajectory correction plates (350) to generate a contribution to the trajectory correction, the method comprising the following steps: Defining operating parameters that describe an operating state of the multi-beam particle beam system (1); Defining operating parameter intervals for each operating parameter in which possible values ​​of the respective operating parameter lie during operation of the multi-beam particle beam system (1); Determining a single-particle beam trajectory deviation from an ideal single-particle beam trajectory for each operating parameter along its operating parameter interval for each of the single-particle beams (3); and Laying out the path correction plates (350), wherein each operating parameter is assigned a path correction plate (350), and wherein for each trajectory correction plate (350) the sizes of its apertures (351) are determined based on the respectively determined trajectory deviations of the associated individual particle beams (3) along the operating parameter interval, and wherein for each trajectory correction plate (350) the shapes of the respective apertures (351) are determined based on the respectively determined trajectory deviations of the associated individual particle beams (3) along the operating parameter interval, so that path deviations which occur due to changes in an operating parameter within its operating parameter interval can be corrected by applying exactly one correction voltage to the path correction plate (350) which is assigned to this operating parameter. [2] Method according to the preceding claim, wherein the respective path deviations of the individual particle beams (3) are determined upon impact in an object plane (101). [3] Method according to one of the preceding claims, wherein the determination of the shape of an aperture (351) also includes determining the orientation of the shape within the path correction plate (350). [4] Method according to one of the preceding claims, wherein, when determining the size of the respective aperture (351) by means of a simulation, a relationship between the size of the aperture (351) and a focus shift caused thereby when a correction voltage is applied to the path correction plate (350) is determined; and / or wherein, when determining the shape of the respective aperture (351) by means of a simulation, a relationship between the shape of the aperture (351) and a changed beam profile caused thereby when a correction voltage is applied to the path correction plate (350) is determined. [5] Method according to the preceding claim, wherein the determination of a relationship between the size of the aperture (351) and a focus shift caused thereby is repeated upon application of at least one further correction voltage; and / or wherein the determination of a relationship between the shape of the aperture (351) and a changed beam profile caused thereby is repeated upon application of at least one further correction voltage. [6] Method according to one of the preceding claims, wherein the correction voltages applied to a trajectory correction plate (350) cover or correct trajectory deviations substantially over the entire operating parameter interval of the trajectory correction plate (350) associated with this operating parameter, and wherein a best fit for the size of the aperture (351) and a best fit for the shape of the aperture (351) for the single particle beam (3) passing through this aperture (351) are determined for all applied correction voltages. [7] Method according to one of the preceding claims, wherein the design of a trajectory correction plate (350) comprises optimizing the individual particle beam profiles towards a beam profile that is as astigmatic as possible after the trajectory correction. [8] Method according to one of the preceding claims, wherein one or more apertures (351) in a trajectory correction plate (350) have or have the shape of at least one of the shapes listed below: Circle, ellipse, shape with twofold symmetry, shape with threefold symmetry, shape with fourfold symmetry, shape with fivefold symmetry, shape with sixfold symmetry, shape with sevenfold symmetry, shape with eightfold symmetry. [9] Method according to one of the preceding claims, wherein one or more apertures (351) in a trajectory correction plate (350) have a free-form shape. [10] Method according to one of the preceding claims, wherein the operating parameters comprise or consist of such parameters that can be selected by a user of the multi-beam particle beam system (1) for the operation of the multi-beam particle beam system (1). [11] Method according to one of the preceding claims, wherein the operating parameters comprise at least one parameter from the following list of parameters: beam current, landing energy, distance of the individual particle beams (3) upon impact in an object plane (101), angle upon impact of the individual particle beams (3) in an object plane (101). [12] Method according to one of the preceding claims, wherein the operating parameters comprise or consist of such parameters which are component-related control parameters. [13] Method according to the preceding claim, wherein the control parameters comprise at least one parameter from the following list of parameters: beam switch excitation, objective lens excitation, field lens excitation. [14] Method according to one of the preceding claims, wherein exactly one path correction plate (350) is assigned to an operating parameter. [15] A method according to any one of the preceding claims, further comprising the step of: Minimize the number of required path correction plates (350). [16] Method according to one of the preceding claims, wherein a number of all operating parameters of the multi-beam particle beam system (1) is greater than the number of all trajectory correction plates (350) of the system. [17] A method according to any one of the preceding claims, further comprising the step of: Selecting a base set of trajectory correction plates (350) that provide a trajectory correction for all trajectory corrections expected in the system to be designed. [18] Computer program product comprising a program code for carrying out the method according to one of the preceding claims. [19] Multi-beam particle beam system (1) designed by means of the method according to one of the preceding claims 1 to 17. [20] Multi-beam particle microscope (1), which has the following features: a multi-beam generator (305) configured to generate a first field of a plurality of charged first single-particle beams (3); a first particle optics system with a first particle-optical beam path, which is configured to image the generated first individual particle beams (3) onto a sample surface (15) in the object plane (101), so that the first individual particle beams (3) impinge on the sample surface (15) at impact locations (5) that form a second field; a detection system (200) with a plurality of detection regions that form a third field; a second particle optics with a second particle-optical beam path, which is configured to image second single-particle beams (9) emanating from the impact locations (5) in the second field onto the third field of the detection regions of the detection system (200); a magnetic and / or electrostatic objective lens (102) 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 generator (305) and the objective lens (102), and arranged in the second particle-optical beam path between the objective lens (102) and the detection system (200); a plurality of trajectory correction plates (350), each having a plurality of apertures (351) through which the plurality of first individual particle beams (3) pass during operation and to which exactly one correction voltage associated with the trajectory correction plate (350) is applied during operation; and a controller (10), wherein apertures (351) of different sizes and different shapes are arranged in at least one of the path correction plates (350), and wherein the controller (10) is configured to control the plurality of trajectory correction plates (350) during operation with a correction voltage that is individually predefined for each trajectory correction plate (350), wherein the respective correction voltages are selected by the controller (10) as a function of operating parameters for the multi-beam particle microscope (1). [21] Multi-beam particle microscope (1) according to claim 20, wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on a beam current or a beam current change; and / or wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on a landing energy or a change in the landing energy; and / or wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on a distance or a change in distance of the first individual particle beams (3) upon impingement of the first individual particle beams (3) in the object plane (101); and / or wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on an angle or an angle change of the first single particle beams (3) upon impingement of the first single particle beams (3) in the object plane (101). [22] Multi-beam particle microscope (1) according to one of claims 20 to 21, wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on an excitation or excitation change of the objective lens (102); and / or wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on an excitation or excitation change of the beam switch (400); and / or wherein one of the trajectory correction plates (350) is adapted to perform a trajectory correction based on an excitation or excitation change of a field lens (307,308,103) arranged in the first particle-optical beam path. [23] Multi-beam particle microscope (1) according to one of claims 20 to 22, wherein the multi-beam generator (305) comprises a trajectory correction plate; and / or wherein a path correction plate (350) is arranged in the region of an intermediate image plane (321). [24] Multi-beam particle microscope (1) according to one of claims 20 to 23, wherein a multi-aperture plate (311) with a plurality of round apertures is arranged directly before and directly after a path correction plate (350), wherein the same voltage, in particular ground potential, is applied to the two multi-aperture plates (311). [25] Multi-beam particle microscope (1) according to one of claims 20 to 24, wherein the multi-beam particle microscope (1) further comprises means for in-situ plasma cleaning of the trajectory correction plates (350); and / or wherein the multi-beam particle microscope (1) further comprises means for providing a low partial pressure of hydrogen gas during operation of the multi-beam particle microscope (1) for cleaning purposes. [26] Multi-beam particle microscope (1) according to one of claims 20 to 25, wherein the multi-beam particle microscope (1) further comprises means for continuously heating the trajectory correction plates (350). [27] Multi-beam particle microscope (1) according to one of claims 20 to 26, which has at least one further trajectory correction plate (350) in the second particle-optical beam path, wherein the further trajectory correction plate (350) has a plurality of apertures (351) through which the plurality of second individual particle beams (9) pass during operation and to which exactly one correction voltage associated with the further trajectory correction plate (350) is applied during operation, wherein apertures (351) of different sizes and different shapes are arranged in the at least one path correction plate (350), and wherein the controller (10) is configured to control the trajectory correction plate (350) during operation with a further correction voltage individually predefined for the further trajectory correction plate (350), wherein the further correction voltage is selected by the controller (10) as a function of an operating parameter for the multi-beam particle microscope (1).

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