Multiple particle beam system with high voltage across a multi-aperture arrangement

Abstract

The invention relates to a multiple particle beam system which can operate with very high kinetic energies within the particle-optical column and nevertheless allows very good single-beam shaping by means of a multi-beam generator. Required correction voltages in the region of a multi-beam generator or of the micro-optical unit are kept low by means of a sophisticated design of the entire column. For this purpose, the charged particles which are emitted by a source or emitter tip and which originally have very high kinetic energy are relatively strongly decelerated before reaching the multi-beam generator, pass through the multi-beam generator relatively slowly, and are then accelerated again to very high kinetic energies. Correction voltages within the multi-beam generator or within the micro-optical unit can thus be kept low. The multi-beam generator or the micro-optical unit itself is at a high-voltage potential. With the solution according to the invention, large parts of the remaining particle-optical column can also be kept at a low-voltage potential and in particular at ground potential.

Description

[0001] Multi-particle beam system with high voltage at a multi-aperture arrangement

[0002] Field of invention

[0003] The invention relates generally to multi-particle beam systems and in particular to multi-beam particle microscopes that operate with a multitude of charged single-particle beams. Specifically, the invention relates to a multi-particle beam system with a multi-aperture arrangement to which a high voltage is applied.

[0004] State of the art

[0005] With the continuous development of increasingly smaller and more complex microstructures, such as semiconductor devices, there is a need for the further development and optimization of planar fabrication techniques and inspection systems for the production and inspection of these small microstructures. The development and fabrication of semiconductor devices, for example, requires verification of test wafer designs, and planar fabrication techniques necessitate process optimization for reliable, high-throughput manufacturing. Furthermore, the analysis of semiconductor wafers for reverse engineering and the customized configuration of semiconductor devices is increasingly required. Therefore, there is a need for inspection tools that can be used with high throughput to examine microstructures on wafers with high accuracy.

[0006] Typical silicon wafers used in the production of semiconductor devices have diameters of up to 300 mm. Each wafer is divided into 30 to 60 repeating sections ("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 millimeters to critical dimensions (CDs) of 5 nm, with feature sizes expected to become even smaller in the near future; future feature sizes or critical dimensions (CDs) below 3 nm, for example 2 nm, or even below 1 nm, are anticipated. At these small feature sizes, defects of critical dimension size must be identified quickly over a very large area.For several applications, the specification requirement for the accuracy of a measurement provided by an inspection instrument is even higher, for example by a factor of two or an order of magnitude. For example, the width of a semiconductor feature must be measured with sub-1 nm accuracy, such as 0.3 nm or even less, and the relative position of semiconductor structures must be determined with a sub-1 nm superposition accuracy, such as 0.3 nm or even less.

[0007] A more 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 7,244,949 B2 and US 2019 / 0355544 A1. In a multi-beam electron microscope, or MSEM, a sample is simultaneously irradiated with a multitude 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 an adjacent 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 pm.A multitude of charged single-particle beams (primary beams) are individually focused onto the surface of the sample under investigation by a common large-field optics system, including a common objective lens. The sample can be, for example, a semiconductor wafer mounted on a wafer holder, which is itself 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, are emitted from the wafer surface. Their respective starting points correspond to the locations on the sample onto which the multitude of primary single-particle beams are focused. The quantity and energy of the interaction products depend, among other things, on the material composition and the topography of the wafer surface.The interaction products form several secondary single-particle beams (secondary beams) that are collected by the common objective lens and directed by a projection imaging system of the multi-beam inspection system onto a detector arranged in a detection plane. The detector comprises several detection areas, each containing several detection pixels, and the detector acquires an intensity distribution for each of the secondary single-particle beams. This yields an image field of, for example, 100 pm x 100 pm. The prior art multi-beam electron microscope comprises an array of electrostatic and magnetic elements. At least some of the electrostatic and magnetic elements are adjustable to adapt the focus position and stigmatization of the multitude of charged single-particle beams.The prior art multi-beam charged particle system also includes at least one intersection plane of the primary or secondary charged single-particle beams. Furthermore, the prior art system includes detection systems to facilitate alignment. The prior art multi-beam particle microscope includes at least one deflection scanner for collectively scanning an area of ​​the sample surface using the plurality of primary single-particle beams to obtain an image field of the sample surface. Further details of a multi-beam electron microscope and a method for operating it are described in US 2023 / 043036 A1, the disclosure of which is incorporated in its entirety by reference into this patent application.

[0008] To separate the particle-optical beam path of the primary beams from the particle-optical beam path of the secondary beams, a so-called beam splitter (also called a beam separator or beam divider) is used. This separation is achieved by means of special arrangements of magnetic fields and / or electrostatic fields, for example, using a Wien filter.

[0009] A key characteristic of a particle microscope, or more generally, of a multi-particle beam system, is its resolution. This is particularly true for the use of a multi-particle beam system in the semiconductor industry.

[0010] It is also generally known that the strength of a Coulomb interaction depends on the electric potential or the kinetic energy of the charged particles. High kinetic energy reduces the Coulomb interaction. Therefore, the state-of-the-art multi-beam particle beam system already operates with high electric potentials and high kinetic energies of the particles within the column. For this purpose, a high voltage is applied to the particle source, and essentially the same applies to the sample stage or the sample itself. For example, high voltages of approximately (+ / -) 25 kV, (+ / -) 28 kV, or (+ / -) 30 kV can be used in each of these locations. The charged particles...Particle beams are accelerated to very high speeds in the vicinity of the particle source, then travel at very high velocity throughout the entire column, and are only decelerated shortly before reaching the sample. Therefore, one option is to further increase the magnitude of the high voltage applied to both the particle source and the sample to further improve the resolution of the multi-particle beam system.

[0011] However, a particle-optical column of a multi-particle beam system, and especially of a multi-beam particle microscope, always includes correction elements to adjust or correct, for example, stigmatism, deflection, and / or field curvature. In multi-particle beam systems that operate with a single column, and especially with a single particle source or tip, multi-beam generation and shaping of the resulting multitude of individual particle beams typically occur in the area of ​​the so-called multi-beam generator or micro-optics. This multi-beam generator or micro-optics is essentially at a low-voltage potential, or more specifically, at ground potential, which facilitates the provision of the necessary correction voltages.

[0012] However, if the charged particles of a multi-particle beam system penetrate the micro-optics with even higher kinetic energy, the interaction time within the micro-optics with the correction elements there is shortened, which would necessitate higher correction voltages. The use of higher correction voltages within the micro-optics, and thus in such a confined space, is limited by the risk of arcing. Furthermore, particle-optical corrections also inherently cause aberrations (possibly other ones), and these are generally greater the higher the correction voltages used.

[0013] A further increase in the number of single-particle beams, which are first generated and then shaped using the multi-beam generator, exacerbates the aforementioned problem of higher correction voltages, especially for field curvature correction in the peripheral areas of a raster arrangement with a large number of single-particle beams.

[0014] DE 10 2023 119 451 A1 discloses a multi-beam particle beam system with an electrostatic booster lens. The kinetic energy of the charged first single-particle beams is selectively increased only in a crossover region of single-particle beams. This approach significantly reduces Coulomb interaction-induced aberrations and simultaneously avoids problems that would arise from applying an even higher (in magnitude) high voltage to the sample stage / sample, which can be of any type. US 2024 / 0038485 A1 discloses a multi-beam particle beam system and deals with a simplified provision of different voltages in a vacuum as well as with the avoidance of flashovers during voltage provision in a vacuum. In this system, a high voltage is provided in a vacuum by means of a high-voltage cable.A voltage of less than 100 V can be provided after optical energy transfer into a high-voltage area. An objective lens array is described as an example application. The publication does not include specific information on voltages along the entire column, nor does it discuss aberrations and their avoidance, or measures for improving the resolution of a multi-particle beam system.

[0015] EP 2 267 751 A2 and DE 10 2018 115 012 A1 are prior art relating to the technological background of the present patent application.

[0016] Description of the invention

[0017] The object of the invention is therefore to provide a multi-particle beam system, and in particular a multi-beam particle microscope, with improved resolution. This system should enable very good resolution even when using an increasing number of individual particle beams. Furthermore, it should allow for very good correction of aberrations by means of micro-optics, even at higher voltages in the particle bed or tip area on the one hand, and in the sample stage area on the other.

[0018] The problem is solved by the subject matter of the independent patent claim. Advantageous embodiments of the invention are described in the dependent patent claims.

[0019] The present patent application claims priority from German patent application No. 10 2025 111 912.0 dated March 27, 2025, the disclosure of which is fully incorporated into the present patent application by reference.

[0020] A fundamental aspect of the invention is to minimize or limit the required correction voltages within the multi-beam generator or micro-optics through a clever design of the entire column. To achieve this, the charged particles emitted from a source or emitter tip, initially with very high kinetic energy, are decelerated relatively sharply before reaching the multi-beam generator, pass through it relatively slowly, and are then accelerated again to very high kinetic energies. This allows the correction voltages within the multi-beam generator or micro-optics to be kept small in magnitude. However, this approach necessitates operating the multi-beam generator or micro-optics themselves at high voltage. While technically challenging, this is feasible.Large parts of the remaining particle-optical column can also be kept at low-voltage potential and, in particular, at earth potential in the solution according to the invention.

[0021] According to a first aspect of the invention, it relates to a plurality of particle beam system having the following features:

[0022] a particle source for emitting a charged particle beam,

[0023] a multibeam generator configured to generate a plurality of charged first single-particle beams from the charged particle beam, wherein the multibeam generator has a multi-aperture arrangement with a filter plate, the filter plate being penetrated by the charged particle beam to form the plurality of first single-particle beams;

[0024] a first particle optics with a first particle-optical beam path configured to image the generated first single-particle beams onto a sample surface of a sample;

[0025] a sample table for arranging the sample;

[0026] a voltage supply unit; and

[0027] a control system for controlling the multiple particle beam system;

[0028] wherein the control system is set up to provide a first high voltage V1 at the particle source by means of the voltage supply unit,

[0029] wherein the control is set up to provide a first low voltage Vn1 by means of the voltage supply unit at a first section of the particle optical beam path, which is arranged in front of the multi-aperture arrangement with respect to the particle optical beam path,

[0030] wherein the control is set up to provide a second high voltage V2 by means of the voltage supply unit at the multi-aperture arrangement, in particular at the filter plate,

[0031] wherein the control is configured to provide a second low voltage Vn2 at a second section of the particle optical beam path, which is arranged downstream of the multi-aperture arrangement with respect to the particle optical beam path, by means of the voltage supply unit, and wherein the control is configured to provide a third high voltage V3 at the sample stage and thus at the sample by means of the voltage supply unit, wherein the first high voltage V1, the second high voltage V2 and the third high voltage V3 have the same sign.

[0032] The identical sign of the first high voltage V1 and the second high voltage V2 is solely explained by the fact that the charged single-particle beams are initially accelerated, but then also decelerated sharply before reaching the sample. Typical landing energies upon impact with the sample are several hundred eV, for example 900 eV or 1.2 keV or 1.5 keV.

[0033] The defined sequence of voltages, namely first high voltage V1 - first low voltage Vn1 - second high voltage V2 - second low voltage Vn2 - third high voltage, as well as the identical sign of the high voltages V1, V2, and V3, ensures the deceleration process described above before the multi-beam generator and the subsequent acceleration process described above after the multi-beam generator. In the patent application, the terms "before" and "after" refer to positions in the particle-optical beam path of the charged particles, starting from the particle source and ending at the sample.

[0034] The charged first single-particle beams can consist of 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.

[0035] The sample can be of any type. Within the scope of this patent application, the term "sample" is used generally to refer to a substrate to be examined or processed. The term "sample" is therefore to be interpreted broadly. Examples of a sample could be, for instance, wafers, lithography masks, or mask blanks.

[0036] The control system according to the invention can be designed as a single unit or in multiple parts. In particular, it can be modular or composed of several functional units.

[0037] The voltage supply unit according to the invention can be designed as a single unit or in multiple parts. In particular, it can be modular or composed of several functional units, for example, with one or more units for providing a high voltage or multiple high voltages, and with one or more units for providing a low voltage or multiple low voltages. The terms high voltage and low voltage are used in this patent application as is customary in electrical engineering: In DC operation, a voltage V > 1500 V is referred to as high voltage. A voltage V < 1500 V is referred to as low voltage. Low voltage can also be extra-low voltage, whereby extra-low voltage in DC operation is V < 120 V and V < 50 V in AC operation. Extra-low voltage can also be earth potential.Within the scope of this patent application, the provision of an earth connection also corresponds to the provision of a voltage by means of the voltage supply unit, even if this is a passive provision.

[0038] The power supply unit can be located wholly, partially, or not at all within an evacuated area of ​​the multi-particle beam system. The same applies to the control system. Specific embodiments are described in more detail below.

[0039] According to one embodiment of the invention, the multi-beam generator comprises a multi-aperture arrangement with a first multi-aperture plate and a multi-aperture corrector arrangement. It is also possible for the multi-beam generator to consist of a multi-aperture arrangement with a first multi-aperture plate and a multi-aperture corrector arrangement. In both cases, the first multi-aperture plate is a so-called filter plate, which is penetrated by the charged particle beam, forming a plurality of first single-particle beams. Furthermore, in both cases, the multi-aperture corrector arrangement is configured to perform individual correction of the generated first single-particle beams. Preferably, the multi-aperture corrector arrangement comprises exclusively a sequence of multi-aperture plates. It then does not include a plate with a single aperture.For example, a multi-aperture array is a stack of numerous multi-aperture plates with different functions or functionalities. However, it is also possible for the multi-aperture array to be monolithic. Individual correction of the generated first single-particle beams includes, for example, individual deflection of the single-particle beams, individual stigmatization of the single-particle beams, or individual focal length adjustment of the single-particle beams. Preferably, the listed corrections are performed electrostatically, but they can also be performed magnetically. For this purpose, corresponding correction elements, such as electrodes, are arranged on the respective multi-aperture plates or multi-aperture arrays in the region of the multiple apertures. The electrodes can be, for example, ring electrodes, cylindrical electrodes, or multipole electrodes.But other designs are also possible.

[0040] The first section of the particle optical beam path, where the first low voltage Vn1 is supplied, can be implemented in various ways. For example, the first section can comprise a steel tube section in which the particle optical beam path runs in a vacuum. However, it is also possible for the first section to be formed by a first aperture plate with a central aperture relative to the particle optical beam path, or to have such an aperture. The length of the first section is also variable in principle. The first section can be relatively long and, for example, also include the area of ​​a collimation lens system / condenser lens system.

[0041] The second low voltage Vn2 is supplied to the second section of the particle-optical beam path. This second section is located downstream of the multi-beam generator in relation to the particle-optical beam path. Preferably, no further particle-optical element is located between the second section and the multi-beam generator. The second section itself can be implemented in various ways. It can, in turn, comprise a steel tube section. According to a preferred embodiment, the second section includes an aperture plate with a central aperture, which is located, in particular, immediately downstream of the multi-beam generator, or the second section consists of this aperture plate.

[0042] According to a preferred embodiment of the invention, the following relationship applies to the magnitude of a potential reduction AV1 induced between the first section and the multi-aperture arrangement: AV1 > 5 kV, preferably AV1 > 10 kV or AV1 > 20 kV. Additionally or alternatively, the following relationship applies to the magnitude of a potential increase AV2 induced between the multi-aperture arrangement and the second section: AV2 > 5 kV, preferably AV2 > 10 kV or AV2 > 20 kV. Within the scope of this patent application, a potential reduction means a deceleration or slowing down of the charged particles, and a potential increase means an acceleration of the charged particles. Both the potential reduction AV1 and the potential increase AV2 can be substantial according to the invention, which in turn enables a more efficient correction of individual particle beams and their properties.In particular, lower correction voltages relative to a reference voltage can be used for the corrections. The potential reduction AV1 and the potential increase AV2 can be equal in magnitude, but this need not be the case. According to a preferred embodiment of the invention, the potential reduction AV1 is at least 30%, at least 40%, or at least 50% relative to the first high voltage V1, and / or the potential increase AV2 is at least 30%, at least 40%, or at least 50% relative to the first high voltage V1.

[0043] According to a preferred embodiment of the invention, the first high voltage V1 at the particle source fulfills the following relationship in terms of magnitude: 25 kV < V1, preferably 30 kV < V1 or 40 kV < V1. Simultaneously, the third high voltage V3 at the sample stage fulfills the following relationship in terms of magnitude: 25 kV < V3, preferably 30 kV < V3 or 40 kV < V3. This means that at the particle source, the charged particles are initially accelerated very strongly and that the charged particles, or the multitude of charged individual particle beams, are decelerated again by (almost) the same amount before reaching the sample stage.

[0044] According to a preferred embodiment of the invention, the first low voltage Vn1 at the first section satisfies the following relationship: 0V < Vn1 < 100V, preferably Vn1 = 0V. Additionally, the second low voltage Vn2 at the second section satisfies the following relationship: 0V < Vn1 < 100V, preferably Vn2 = 0V. This has the advantage that a large part of the column can still be kept at low voltage or even at ground potential. Only the area around the multi-beam generator or the multi-aperture arrangement is at high voltage. This generally simplifies the design of the multi-particle beam system, since only a short section is at high voltage and needs to be isolated from the environment.

[0045] According to a preferred embodiment of the invention, the multi-beam generator has a housing, and the multi-aperture arrangement is arranged within the housing. Thus, the filter plate and the multi-aperture corrector arrangement are also located within the housing. This housing can be powered by high voltage. In this way, the multi-beam generator, which operates at high voltage, can be designed as a module. Preferably, the housing surrounds the multi-aperture arrangement in such a way that the housing has one or more openings only for the entry and exit of the particle beams, but is otherwise closed except for cable glands for supplying voltages and / or control signals. The housing then has, for example, a top, a bottom, and also a surrounding side wall.Providing a housing also facilitates the electrical isolation of the multi-beam generator at high voltage from other particles of the multi-particle beam system, and in particular from the first and second sections. Furthermore, the housing can also incorporate beam shaping functions, and it is possible to manufacture the housing as a module and adjust the multi-beam generator by adjusting the housing. Specific embodiments in this regard will be discussed in more detail below.

[0046] According to a preferred embodiment of the invention, the housing and the filter plate of the multi-aperture arrangement are at the same potential. Preferably, the second high voltage V2 is applied to both the housing and the filter plate. Thus, there is no potential difference between the housing and the filter plate. This contributes to ensuring that an illuminating particle beam, which strikes the filter plate to form the multitude of individual particle beams, can illuminate this filter plate homogeneously and, in particular, also telecentrically.

[0047] According to a preferred embodiment of the invention, the first section comprises a first aperture plate with an aperture centrally located with respect to the particle-optical beam path. Additionally or alternatively, the second section comprises a second aperture plate with an aperture centrally located with respect to the particle-optical beam path. The first and / or second low voltages, Vn1 and Vn2 respectively, are then applied to the first and / or the second aperture plate, respectively. In both cases, this can explicitly be ground potential.

[0048] According to a preferred embodiment of the invention, the housing has a top surface on the particle source side with a central aperture, located relative to the particle-optical beam path, serving as the entrance opening for the charged particle beam into the housing. The central aperture of the top surface is dimensioned such that it is no larger than the central aperture of the first aperture plate. In other words, the central aperture of the top surface is at least as large as the central aperture of the first aperture plate. This, in turn, contributes to the precise and, in particular, telecentric illumination of the subsequent filter plate of the multi-aperture arrangement.

[0049] Furthermore, it is preferred that the minimum distance between the top of the housing and the filter plate of the multi-aperture arrangement be chosen to be as large as possible: In this way, any remaining electric field in front of the filter plate can decay more effectively. A minimum distance between the top of the housing and the filter plate is, for example, at least 1 mm, 5 mm, or 10 mm. According to a preferred embodiment of the invention, a shielding electrode is arranged in the region of the central aperture of the top of the housing, or several shielding electrodes are arranged in the region of the central aperture of the top of the housing. This further reduces the electric field at the filter plate of the multi-aperture arrangement. This, in turn, facilitates precise and, in particular, telecentric illumination and thus the generation of single-particle beams in the most precise way possible.

[0050] According to a preferred embodiment of the invention, the housing has a bottom surface on the sample side with a central aperture, relative to the particle-optical beam path, serving as an exit opening for the first individual particle beams. The central aperture of the bottom surface is dimensioned such that it is no larger than the central aperture of the second aperture plate. This, in turn, can reduce an electrostatic field between a final multi-aperture plate of the multi-aperture corrector arrangement and the bottom surface of the housing, if desired.

[0051] According to an alternative embodiment of the invention, the housing has a bottom surface on the sample side with a multi-aperture plate arranged centrally with respect to the particle-optical beam path, through which the first individual particle beams exit the housing. This centrally arranged multi-aperture plate is then thus a final multi-aperture plate of the entire multi-aperture arrangement.

[0052] In both of the alternative embodiments described above, a final multi-aperture plate of the multi-aperture arrangement exists. With the embodiment of the invention now described, a so-called aperture-lens effect can be realized: According to this embodiment of the invention, a control electrode with a central aperture relative to the particle-optical beam path is arranged between the housing and the second aperture plate. The control unit is configured to individually provide a control voltage to the control electrode via the voltage supply unit, so that the distance between the first individual particle beams can be adjusted. In other words, the distance between the foci of the first individual particle beams in a first field can be adjusted. The control electrode is then part of the multi-beam generator.It essentially serves as the counter electrode for a multi-lens arrangement in the multi-beam generator. Specifically, the aperture lens effect is induced by an electric field between the final multi-aperture plate of the multi-beam generator on the one hand and the control electrode, or counter electrode, of the multi-beam generator on the other. The aperture lens effect and the adjustment of the distance between the first individual particle beams are known in principle. What is particularly noteworthy is that this effect can now also be realized in a high-voltage multi-beam generator. The adjustability of the distance between the first individual particle beams relative to each other, provided by the aperture lens effect, is therefore retained.

[0053] According to an alternative embodiment of the invention, the multi-aperture arrangement comprises a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams, and an application-specific integrated circuit (ASIC) for controlling the multi-aperture corrector arrangement is arranged in the housing. The use of application-specific integrated circuits for providing correction signals or correction voltages to multi-aperture corrector arrangements is already known in the prior art. According to the invention, the application-specific integrated circuit is now located at a high-voltage potential.

[0054] According to a preferred embodiment of the invention, the voltage supply unit is configured to generate at least one reference voltage Vref in the high-voltage range and at least one control voltage Vc that differs from the reference voltage. The difference AVref between the reference voltage Vref and the control voltage Vc satisfies the following relationship: Vref < AVref < 200V, preferably 0V < AVref < 150V or 0V < AVref < 100V. The difference AVref is therefore only a small fraction of the reference voltage Vref, which represents a high voltage. Thus, very precise and small deviations from a reference voltage Vref are achieved in the high-voltage range. The deviations AVref from the reference voltage are typically those voltages required to selectively control the multi-aperture corrector arrangement for the correction purposes already described.For focal length adjustments, for example during field curvature correction, AVref differences of up to 200 V are sufficient, and in high-voltage applications, preferably only up to ±100 V, depending on the reference voltage Vref. For adjusting deflection or tilt, AVref differences in the range of approximately ±5 V to ±20 V are typical. Even smaller AVref differences of up to approximately ±1 V are typically required for adjusting and / or correcting stigma.

[0055] According to a preferred embodiment of the invention, a circuit is arranged in the housing which is configured to generate a larger number k > n of voltages from a number n of voltages. Here, both n and k are natural numbers. In this embodiment, the n voltages are introduced into the housing from the outside, and the k voltages are used to control the multi-aperture corrector or the associated multi-aperture plates with the electrodes arranged in the aperture region. Thus, in this embodiment of the invention, only a few voltages, namely n, are introduced into the housing from the outside. This is advantageous because introducing voltages into a high-voltage area such as the housing places special demands on, for example, the insulation of the conductors and / or the vacuum tightness of the conductors.Therefore, it can be advantageous to generate a large proportion, namely k, of the voltages by means of the circuit only within the housing and thus already within the high-voltage area. According to a preferred embodiment of the invention, the following relationship applies to the k / n ratio: n / k > 2, preferably n / k > 5, and most preferably n / k > 8 or n / k > 20. However, it is also possible to supply all voltages externally, or to supply only one voltage externally and generate all correction voltages within the housing.

[0056] According to a preferred embodiment of the invention, the voltage supply unit is multi-part. It then comprises an inner voltage supply unit that is arranged inside the housing. Voltages supplied by this inner voltage supply unit for the multi-aperture corrector arrangement therefore do not need to be introduced into the housing from the outside.

[0057] According to a preferred embodiment of the invention, the internal power supply unit comprises a rechargeable battery. This has the advantage that a charging process can take place at times when this recharging does not generate any interfering electromagnetic fields that could negatively affect the beam quality of the multi-particle beam system. Recharging can, for example, occur during downtime or maintenance of the multi-particle beam system. A charging cable can then be used for the recharging itself. Alternatively, it is conceivable to replace the battery during maintenance work.

[0058] According to a preferred embodiment of the invention, a data line for providing control data for the multi-aperture corrector arrangement is routed from the outside into the housing. A fundamental distinction can be made between the provision of voltages on the one hand and the provision of data on the other. According to an alternative embodiment of the invention, control data for the multi-aperture corrector arrangement is provided wirelessly from the outside into the housing. In this case, a dedicated line is not required. It is emphasized again that this refers to the provision of control data and not to the provision of voltages or power for a power supply.

[0059] According to an alternative embodiment of the invention, the control data is provided from the outside into the housing in one of the following ways: optically, by means of infrared signals, and / or by means of radio signals. Optical provision can be achieved, for example, by means of an optical fiber or by optical transmission through a vacuum. Data encoding in an optical manner, via infrared signal, or by means of radio signals is already known from other areas of the prior art.

[0060] The term "from outside into the housing" defines the introduction of control data into a high-voltage area (within / the housing) from outside the high-voltage area (outside the housing). Additionally, the term may optionally also include a transfer from outside the vacuum of the multi-particle beam system into the vacuum of the multi-particle beam system, but this is not mandatory. According to one embodiment, the transfer of control data first occurs outside the high-voltage area, and thus not yet within the high-voltage area, passing through the vacuum boundary, and then only within the vacuum from a low-voltage area to a high-voltage area.

[0061] According to a preferred embodiment of the invention, the housing is electrically insulated relative to the first and second sections. Additionally or alternatively, the housing is adjustable relative to the first and / or second sections. For example, the housing, which is under high voltage, is arranged within an outer, grounded housing. The first and second sections can be part of this outer housing. For example, the housing is suspended within the outer housing or screwed to it in an insulating manner. Ceramic balls can also be used as spacers and for alignment or adjustment purposes.These ceramic balls are insulating, and for estimation purposes, the diameter of a ceramic ball in millimeters should correspond at least to the maximum potential reference in kV between the housing and the outer casing. Alternatively, with three-point support, the ceramic balls can be suspended from a grounded flexible wire or spring, and the ceramic balls can be positioned over the outer casing using a pipe clamp. These and other measures ensure the required low mechanical tolerances between the housing and the first and second sections.

[0062] According to a preferred embodiment of the invention, the multi-aperture corrector arrangement is configured to perform at least one of the following corrections individually for each of the single-particle beams: a deflection, a stigmatization, a focal length change.

[0063] According to a preferred embodiment of the invention, the multiple particle beam system is a multiple particle microscope. However, the multiple particle beam system can also be configured differently, for example as a multiple lithography system.

[0064] The embodiments of the invention described above can be combined in whole or in part, provided that no technical contradictions result.

[0065] The invention will be better understood with reference to the accompanying figures. These show:

[0066] Fig. 1: shows a schematic representation of a multi-beam particle microscope (MSEM); Fig. 2: shows schematically the voltages applied to a multi-beam particle beam system according to the prior art;

[0067] Fig. 3: schematically shows voltages applied to a multi-particle beam system according to the invention;

[0068] Fig. 4: schematically shows an arrangement with a multi-beam generator at high voltage;

[0069] Fig. 5: schematically illustrates an aperture lens effect according to the prior art;

[0070] Fig. 6: schematically shows an implementation of an aperture lens effect in a multi-beam generator at high voltage;

[0071] Fig. 7: schematically shows an implementation of an aperture lens effect in a multi-beam generator at high voltage;

[0072] Fig. 8: schematically shows a voltage supply and control system for a multi-beam generator operating at high voltage; Fig. 9: schematically shows a voltage supply and control system for a multi-beam generator operating at high voltage;

[0073] Fig. 10: schematically shows a voltage supply and control system for a multi-beam generator at high voltage;

[0074] Fig. 11: schematically illustrates the generation of multiple voltages in a vacuum; Fig. 12: schematically illustrates the generation of multiple voltages in a vacuum; Fig. 13: schematically shows the mounting of a multi-beam generator operating at high voltage; and

[0075] Fig. 14: shows schematically a mounting of a multi-beam generator operating at high voltage.

[0076] Fig. 1 schematically shows a multi-particle beam system 1 in the form of a multi-beam particle microscope 1. The multi-beam particle microscope 1 has a beam generation device 300 with a particle source, for example, an electron source. Charged particles or electrons are generated by the beam generation device 300, for example, by thermal field emission. The emitted charged particles form a diverging particle beam 309, which is collimated by a sequence of condenser lenses 303.1 and 303.2 and strikes a multi-beam generator 305 with a multi-aperture arrangement. The multi-beam generator 305 comprises several multi-aperture plates 304, 306 and a field lens 307. A multitude of single-particle beams 3 or 306 are emitted by the multi-beam generator 305.Single-electron beams 3 are generated, arranged in a field which is mapped onto another field formed by beam spots 5 in the object plane 101. The distance between the centers of apertures of a multi-aperture plate 306 can be, for example, 5 pm, 100 pm, and 200 pm. The diameters D of the apertures are smaller than the distance between the centers of the apertures; examples of the diameters are 0.2 times, 0.4 times, and 0.8 times the distances between the centers of the apertures.

[0077] The multi-beam generator with the multi-aperture arrangement and the field lens 308 are configured to generate a multitude of focal points 323 of primary beams 3 in a grid arrangement on a surface 321. The surface 321 need not be a flat surface, but can be a spherically curved surface to accommodate field curvature of the subsequent particle optical system.

[0078] The multi-beam particle microscope 1 further comprises a system of electromagnetic lenses 103 and an objective lens 102, which reduce the size of the beam foci 323 from the intermediate image surface 321 onto the object plane 101. The first individual particle beams 3 pass through the beam splitter 400 and a collective beam deflection system 500, which deflects the multitude of the first individual particle beams 3 during operation and scans the image field. The first individual particle beams 3 incident on the object plane 101 form, for example, a substantially regular field, with distances between adjacent point locations 5 being, for example, 1 pm, 10 pm, or 40 pm. The field formed by the point locations 5 can, for example, have a rectangular or hexagonal symmetry.

[0079] 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 located 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.

[0080] The primary particles 3 striking object 7 generate interaction products such as secondary electrons, backscattered electrons, or primary particles that have undergone a reversal of motion for other reasons. These products originate from the surface of object 7 or from the first plane 101 or object plane 101. The interaction products emanating from the surface 15 of object 7 are shaped into secondary particle beams 9 by the objective lens 102. After passing through the objective lens 102, the secondary beams 9 pass through the beam splitter 400 and are directed to a projection system 200. The projection system 200 has an imaging system 205 with projection lenses 206, 208 and 210, a contrast aperture 214 and a multi-particle detector 207. The impact points 25 of the second single-particle beams 9 on the detection areas of the multi-particle detector 207 are located in a third field at a regular distance from each other.Example values ​​are 10 pm, 100 pm and 200 pm.

[0081] The multi-beam particle microscope 1 further comprises a computer system or a control unit or controller 10, which in turn may be designed as a single unit or as a multi-part unit, and which is designed both for controlling the individual particle-optical components of the multi-beam particle microscope 1 and for evaluating and analyzing the signals obtained with the multi-detector 207 or the detection unit.

[0082] Further information on such multi-beam particle beam systems or multi-beam particle microscopes 1 and components used therein, such as particle sources, multi-aperture plates and lenses, can be obtained from the international patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596 A1, WO 2011 / 124352 A1 and WO 2007 / 060017 A2 and the German patent applications DE 10 2013 016 113 A1 and DE 102013014976 A1, the disclosure of which is incorporated in full by reference into the present application.

[0083] Figure 2 schematically shows voltages applied to a multi-particle beam system 1 according to the prior art. For the sake of simplicity, only a single particle beam 3 is shown in the figure. The prior art multi-particle beam system 1 operates with high electrical potentials and high kinetic energies of the particles within the column. In the example shown, a negative voltage of -30 kV is applied to the particle source or emitter 301. Charged particles emitted from the source 301 then pass through the extractor 302 before reaching their highest kinetic energy at section 330. Ground potential is applied to this section 330. The ground potential can be provided, for example, at a beam tube section in which the charged particles move. The charged particles then pass through a collimation lens system with magnetic lenses 303.1 and 303.2.This collimates, for example, an initially divergent particle beam 309. The charged particles then pass through a section 331, which is also at ground potential (0V). In the example shown, section 331 comprises an aperture plate with a circular opening centrally aligned with respect to the particle-optical axis Z.

[0084] The charged particles then pass through a multi-beam generator 305. This generator comprises a filter plate 304 and a plurality of multi-aperture plates 306.1, 306.2, and 306.3. Passing through the filter plate 304, the plurality of individual particle beams 3 are generated. Passing through the multi-aperture plates 306.1, 306.2, and 306.3, the charged individual particle beams 3 are optically shaped. The multi-aperture plates 306.1, 306.2, and 306.3 thus form a multi-aperture corrector arrangement 366.

[0085] After passing through the multi-beam generator 305, the charged single-particle beams 3 pass through a section 332. In the example shown, this is designed as an aperture plate with a singular opening centered on the particle-optical axis Z. Earth potential (0V) is applied to this singular aperture plate 332.

[0086] The charged single-particle beams 3 then pass through an imaging particle optic 340, which may include, for example, one or more field lenses, one or more objective lenses, and possibly other correction elements. The imaging particle optic 340 focuses the charged single-particle beams 3 onto an object plane 101 of a sample 7. In the example shown, a negative high voltage of -29 kV is applied to the sample 7 or to an associated sample stage 600. Therefore, in the example shown, the impact energy on the sample 7 is approximately 1 keV, assuming the charged particles are electrons.

[0087] As illustrated in Figure 2, it is important that the multi-beam generator 305 is traversed by the charged particles or charged single-particle beams 3 with high kinetic energy. If this kinetic energy increases further, for example, because an even higher voltage is applied to both the particle source 301 and the sample 7 or sample stage 600, beam shaping using the multi-aperture corrector arrangement 366 becomes more difficult, and higher voltages are required for the corresponding correction or adjustment. The same applies if the number of single-particle beams increases further, since at least for single-particle beams 3 located further out in the field of the single-particle beams 3, there is a higher field curvature that must be corrected or compensated for.

[0088] The problem addressed is now addressed by the inventive multi-particle beam system 1, which is shown by way of example in Figure 3: As always, the same reference numerals correspond to the same features of the invention. Unlike in Figure 2, a further high voltage, which is -25 kV in the example shown, is now applied to the multi-aperture arrangement with the filter plate 304 and the multi-aperture corrector arrangement 366. Compared to the representation in Figure 2, the charged particles in Figure 3 are therefore significantly slower. Before entering the multi-beam generator 305, the charged particles have thus been decelerated. The deceleration takes place between the first section 331 and the multi-beam generator 305. Only after passing through the multi-beam generator 305 or the multi-aperture corrector arrangement are the charged particles, or now the charged single-particle beams 3, accelerated again, in the example shown back to their original speed, if applicable.Maximum kinetic energy. Specifically, the re-acceleration takes place between the multi-beam generator 305 and the second section 332, which, in the example shown, is at ground potential. Instead of ground potential, a different low voltage Vn1 and Vn2 could also be applied to the first section 331 and the second section 332, respectively, whereby these two low voltages can have the same value, but need not. Because the charged particles within the multi-beam generator 305 are now significantly slower, the correction voltages required at the multi-aperture corrector arrangement 366 can be reduced relative to a differential voltage. This also opens up possibilities for a further increase in the total number of single-particle beams 3 of the multi-particle beam system 1.

[0089] The voltage values ​​shown in Figure 3 are only exemplary and not limiting to the invention. For example, a potential reduction AV1 occurs between the first section 331 and the multi-aperture arrangement 304, 306, which satisfies the following relationship in magnitude: AV1 > 5 kV, preferably AV1 > 10 kV or AV1 > 20 kV. Additionally or alternatively, the following relationship can apply to a potential increase AV2 between the aperture arrangement 304, 306 and the second section 332: AV2 > 5 kV, preferably AV2 > 10 kV or AV2 > 20 kV. However, both the potential reduction AV1 and the potential increase AV2 can be even greater, as is already shown in Figure 3 with a difference of 25 kV or even more.

[0090] For example, the first high voltage V1 at the particle source 301 can satisfy the following relationship in terms of magnitude: 25kV < V1, preferably 30kV < V1 or 40kV < V1. Additionally, the third high voltage V3 at the sample stage 600 can satisfy the following relationship in terms of magnitude: 25kV < V3, preferably 30kV < V3 or 40kV < V3.

[0091] According to an example, a first low voltage Vn1 at the first section 331 satisfies the following relation in terms of magnitude: 0V < Vn1 < 100V, preferably Vn1 = 0V. Additionally, in this example, the second low voltage Vn2 at the second section 332 satisfies the following relation in terms of magnitude: 0V < Vn2 < 100V, preferably Vn2 = 0V.

[0092] Figure 4 schematically shows an arrangement with a multi-beam generator 305 operating at high voltage (HV). In the illustrated embodiment, the multi-beam generator 305 has a housing 350. The multi-aperture arrangement 304, 366 is arranged in the housing 350. In the illustrated embodiment, the housing 350 and the filter plate 304 are at the same potential. Specifically, in this example, the second high voltage V2 is applied to both the housing 350 and the filter plate 304. This results in no potential difference, and therefore no electric field, between the housing 350 and the filter plate 304, allowing charged particles striking the filter plate 304 to strike it without any field influence and, in particular, telecentrically. This enables particularly effective filtering and generation of the charged single-particle beams 3.In the example shown, the housing 350 comprises, on the particle source side, a top surface 351 with a central aperture (relative to the particle-optical beam path) serving as the entrance opening for the charged particle beam into the housing 350. In the example shown, this central aperture has a diameter d2. Furthermore, on the sample side, the housing 350 has a bottom surface 352 with a central aperture (relative to the particle-optical beam path) serving as the exit opening for the first individual particle beams 3. In the example shown, this aperture has a diameter d3.

[0093] In the embodiment shown in Figure 4, the first section 331 is arranged above, or on the particle source side, of the multi-beam generator 305 as the first aperture plate with a central aperture relative to the particle-optical beam path, which in the example shown has a diameter d1. Furthermore, the second section 332 is arranged below the multi-beam generator 305, or on the sample side, as the second aperture plate with a central aperture relative to the particle-optical beam path Z, wherein this central aperture has a diameter d4.

[0094] In the example shown, diameters d1 and d2 are identical, as are diameters d3 and d4. According to a preferred embodiment of the invention, diameter d2 is not larger than diameter d1. In other words, the top surface 351 is drawn far enough inward or forward toward the particle-optical axis Z to prevent the charged particles from being exposed to an electric field when they strike the filter plate 304. A maximum distance a between the filter plate 304 and the top surface 351 of the housing 350 also contributes to the field decay in front of the filter plate 304. This distance a should be, for example, at least 1 mm, at least 5 mm, at least 10 mm, or even more.

[0095] In the example shown, the diameters d3 and d4 are also identical. According to a preferred embodiment of the invention, d3 is not larger than d4, or in other words, d4 > d3.

[0096] According to an alternative embodiment, the housing 350 has a bottom surface 352 on the sample side with a multi-aperture plate arranged centrally with respect to the particle-optical beam path, through which the first individual particle beams 3 emerge from the housing 350. This embodiment can offer advantages in utilizing the so-called aperture lens effect: Figure 5 schematically illustrates an aperture lens effect according to the prior art: The multi-aperture arrangement 304, 306, 366 according to Figure 5 is generally at ground potential. The multi-aperture arrangement 304, 306, 366 comprises a final multi-aperture plate 306f. A singular aperture plate 354, which is subjected to voltage or high voltage HV, is arranged with respect to the particle-optical beam path downstream of the final multi-aperture plate 306f. This singular aperture plate 354 represents a control electrode 354.Between the final multi-aperture plate 306f, which is formed without separate electrodes, and the control electrode 354, a strong electric field exists, extending partially into the openings of the final multi-aperture plate 306f. The specific manner of this extension depends on the position of the individual apertures in the final multi-aperture plate 306f. As a result, depending on the high voltage applied to the counter electrode or control electrode 354, a distance between the individual particle beams 3 in a first field can be set relative to each other. The charged individual particle beams 3 can thus be, so to speak, somewhat separated. The foci 323, which are subsequently imaged onto the object plane 101 during the particle-optical imaging process, are located in the first field.The provision of a control electrode 354 after a final multi-aperture plate 306 thus provides a setting possibility for a particle-optical parameter (distance between the individual particle beams).

[0097] Figure 6 schematically shows an implementation of an aperture lens effect in a multi-beam generator 305 at high voltage: In the example shown, the housing 350 has a bottom surface 352 on the sample side with a multi-aperture plate 306f arranged centrally with respect to the particle-optical beam path, through which the first individual particle beams 3 emerge from the housing. Due to the potential difference between the single aperture plate or the second section 332, which is at ground potential, and the final multi-aperture plate 306f, which is at high voltage, the described aperture lens effect already occurs. However, when ground potential is provided, the size of the beam spacing between the individual particle beams 3 is already fixed in principle.If a controllable control electrode 354 is additionally used between the second section 332 and the underside 352 of the housing 350, the beam spacing between the individual particle beams can again be adjusted after passing through the multi-beam generator 305. Specifically, the spacing of the individual particle beams 3 in the first field formed by the foci 323 is again adjusted. The variable spacing between the individual particle beams 3 is indicated in Figures 5 and 6 by the double arrows between the individual particle beams 3. The voltage values ​​with which the control electrode 354 can be controlled can be in the low-voltage range. However, it is also possible for a further high voltage to be applied to the control electrode 354. Crucial for realizing the aperture lens effect is the voltage difference between the final multi-aperture plate 306f on the one hand and the control electrode 354 on the other.

[0098] Figure 7 schematically shows another implementation of an aperture lens effect in a high-voltage multi-beam generator 305. Here, the underside 352 again has a singular opening, but near this opening is a final multi-aperture plate 306f of the multi-aperture corrector arrangement 366. The aperture lens effect is realized between the openings of this final multi-aperture plate 306f, which is at high voltage, and the singular aperture plate 332, which in the example shown is at ground potential. The same applies if, optionally, a control electrode 354 is arranged between the second aperture plate 332 and the underside 352 of the housing 350.

[0099] Additionally, the embodiment shown in Figure 7 has one or more shielding electrodes 355 in the region of the central aperture of the top surface 351 of the housing 350. These further contribute to ensuring that the illuminating particle beam 309 can strike the filter plate 304 telecentrically, or that an electric field between the first aperture plate 331 and the top surface 351 of the housing 350 has already completely decayed at the surface of the filter plate 304.

[0100] Figure 8 schematically shows a voltage supply and control system for a multi-beam generator 350 operating at high voltage (HV). In the example shown, this high voltage forms the reference voltage Vref. Deviations from this reference voltage Vref are used to shape the individual particle beams 3 by means of the multi-aperture corrector arrangement 366. The multi-aperture corrector arrangement 366 has a plurality of multi-aperture plates. For example, one or more electrodes can be arranged in the region of the individual apertures of the multi-aperture plates. These can be, for example, cylindrical electrodes, ring electrodes, or multipole electrodes. However, it is also possible for individual multi-aperture plates to be monolithic, so that the same voltage is applied everywhere in the region of the apertures, which in turn influences the beam shaping in interaction with other particle-optical elements.This can occur, for example, when a sequence of single lenses is provided, or when a multi-aperture plate and a single-aperture plate interact in the aperture-lens effect. Depending on the specific design of the multi-aperture arrangement 304, 366, or the specific design of the multi-aperture corrector arrangement 366, one or even several individually adjustable correction voltages must be applied in the area of ​​the apertures or at the electrodes located there. To provide these correction voltages, the embodiment shown in Figure 8 includes an application-specific integrated circuit 705 or an ASIC 705 in the housing 350. Of course, several application-specific integrated circuits 705 can also be provided. The ASIC 705 generates the individual voltages, which are then provided at the electrodes in the area of ​​the individual apertures.This voltage is supplied with high precision. This requires providing a high voltage accurate to within a few volts, for example, 29 kV + / - 2 V or 50 kV + / - 2 V. Based on the data provided by the ASIC 705, the generated voltages can vary. This control data must, of course, be provided in or for the high-voltage range.

[0101] Furthermore, it is possible that the multi-aperture corrector arrangement 366 has one or more multi-aperture plates that are not supplied with voltage by means of an ASIC 705. Instead, control voltages Vc can be applied directly to a multi-aperture plate 306.

[0102] The principle described above has a certain general validity. However, there are various ways in which the reference voltage Vref, control data, and / or control voltages Vc for the multi-beam generator 305 can be provided at high voltage: In principle, it is possible to introduce the necessary voltages and data from the outside into the high-voltage area of ​​the multi-beam generator 305. For this purpose, appropriately high-voltage-resistant and / or vacuum-resistant bushings are used. Figure 8 shows this case schematically: A multi-part voltage supply unit 700 is arranged in a grounded environment, which can also be surrounded by air 920. In the example shown, it comprises a first voltage supply unit 700.1, which provides reference voltages Vref for the ASIC 705, and a second voltage supply unit 700.2, which provides control voltages Vc.Furthermore, the control system 10 of the multi-particle beam system 1 includes a control unit 10.1, which is also located in a grounded area and, if necessary, surrounded by air 920 – and thus easily accessible. In contrast, other components in the example shown are located in a vacuum 921. While the transfer of lines for voltage on the one hand and data on the other from a low-voltage environment or from an environment at earth potential into a high-voltage area is difficult, it is, in principle, solved in the prior art. In this context, reference is also made to the already cited US 2024 / 0038485 A1.

[0103] However, solutions also exist that require fewer cable penetrations and, in particular, fewer high-voltage vacuum feedthroughs: Figure 9 schematically shows another embodiment with a voltage supply and control system for a particle beam generator 350 operating at high voltage (HV). In the example shown, the voltage supply unit 700 is again multi-part and comprises an inner supply unit 700.1, which is located inside the housing 350 and thus in a high-voltage area. This inner voltage supply unit 700.1 can, for example, be designed as a rechargeable battery. Alternatives include, for example, a non-rechargeable battery or a high-capacity capacitor. Another alternative is an inductive or capacitive energy transfer system.

[0104] An external power supply unit 700.2 provides the necessary energy to the internal power supply unit 700.1 via a charging line 360. For example, the charging line 360 ​​can be active or connected to the multi-particle beam system 1 only during times outside of imaging or image acquisition periods. This prevents disruptive electromagnetic fields from negatively affecting the quality of the particle-optical imaging of the multi-particle beam system 1 during the charging process itself. Alternatively, the battery 700.1 can be recharged inductively instead of using the charging line 360.

[0105] In the example shown, the control unit 10 is also multi-part: Part of the control unit 10.1 is located in an external area, for example in a grounded environment that does not need to be evacuated. In contrast, an internal control unit 10.2 is located inside the housing 350 of the multi-beam generator 305 and thus in a high-voltage environment and in a vacuum.

[0106] Figure 9b illustrates the interaction between the internal supply unit 700.1 and the internal control unit 10.2: The internal voltage supply unit 700.1 provides the required voltage to the internal control unit 10.2, which is configured as a high-voltage controller, and to the ASIC 705 or ASICs 705, which can be configured as a multi-channel controller (optionally as a high-voltage controller). This voltage can be the reference voltage Vref already described and / or control voltages Vc. Specifically, a reference voltage Vref can be provided to the ASIC 705, and control voltages Vc can be provided to the high-voltage controller 10.2. Both the ASIC 705 and the voltage controller 10.2 receive control signals from the external controller 10.1. In the example shown, a data line 361 is depicted for this purpose.However, it is also possible to transmit data wirelessly, for example optically, using infrared signals, and / or using radio signals. The example shown also includes an output line 362. This output line 362 can be used, for example, to apply a voltage to a monolithic multi-aperture plate. Of course, it is possible to use several ASICs 705 instead of one, and / or several voltage controllers 10.2 instead of a single voltage controller 10.2, thereby supplying a larger number of multi-aperture plates with global voltages for the entire multi-aperture plate, with an individual voltage per aperture, or with several individual voltages per aperture. In this way, for example,Individual deflections of the single-particle beams, individual stigmatizations of the single-particle beams, or individual focal length changes of the single-particle beams can be set.

[0107] Figure 10 schematically shows a voltage supply and control system for a multi-beam generator 305 operating at high voltage according to a further embodiment of the invention: Compared to the embodiment shown in Figure 9, an additional control unit 10.3 is provided inside the housing 350. This control unit 10.3 performs the functions of the control unit 10.1 according to Figure 9. In this respect, the introduction of control signals from the control unit 10.1 into the high-voltage area can be further simplified. In this case as well, the provision of control data from outside into the housing 350 can be wireless and, in particular, optical, using infrared signals and / or radio signals. For the transmission of control signals optically, for example, an optical fiber can be used, or signals can be transmitted directly through the vacuum.

[0108] Figures 9 and 10 show the voltage supply unit 700.2 and the control unit 10.1 only schematically. Both may already be located within a vacuum. However, it is also possible that they are located outside a vacuum. In this case, for example, the charging line 360 ​​and the data line 361 would also pass through the vacuum boundary.

[0109] According to an example, the voltage supply unit 700.1, 700.2 is configured to generate at least one reference voltage Vref in the high-voltage range and at least one control voltage Vc different from the reference voltage, where the difference AVref between the reference voltage Vref and the control voltage Vc satisfies the following relation: OV < AVref < 200V, preferably OV < AVref < 150V or OV < AVref < 100V. However, other values ​​for the specified difference AVref are also possible.

[0110] In principle, it is advantageous to minimize the number of conductors from the surrounding environment that need to be introduced into the high vacuum or high-voltage area. According to a preferred embodiment of the invention, a circuit is therefore arranged in the housing 350, configured to generate a larger number k > n of voltages from a number n of voltages, where k and n are natural numbers. The voltages n are introduced into the housing from the outside, and the voltages k are used to control the multi-aperture corrector 366.

[0111] Figure 11 schematically shows the generation of multiple voltages in a vacuum: The area shown in Figure 11a is essentially subdivided into a vacuum region 921 and an ambient region (air 920). Within the vacuum 921, the high voltage must also be provided. In the example shown, two high voltages, V2+AV and V2-AV, are provided in the ambient region. These are introduced into the vacuum 921 and the high-voltage region, respectively, via high-voltage-resistant and vacuum-tight feedthroughs. In the example shown, the circuit is implemented using two resistors that also have the same ohmic resistance. Due to the voltage divider principle, three voltages can thus be generated from the two voltages V2+AV and V2-AV: In addition to the input voltages, the high voltage V2 is also generated in the vacuum 921.This principle can be further extended with the help of appropriately designed circuit arrangements, so that significantly more different high voltages can be generated within the vacuum or within the high-voltage area and especially within the housing 350 than can be applied from the outside.

[0112] Figure 11b shows another example: Only a single conductor is introduced into the vacuum 921 from the outside. A low voltage is modulated onto a high voltage V2 on this conductor. The modulated component is labeled AV_AC in Figure 11b. Inside the vacuum 921, two DC voltages are generated from the modulated high voltage V2+AV_AC: the high voltage V2 and the voltage V2+AV_DC. In principle, the value of the modulated component is arbitrary, but in practice it is limited by the dielectric strength of the components, the permissible AC component of the generated DC voltages (ripple), and the suitability of the application. According to one embodiment, V2 = 10 kV and AV_DC = 1000 V. The modulation component is then 1%.

[0113] Figure 12 schematically shows another example of generating multiple voltages in a vacuum 921. Figure 12a is based on the principle of rectifier AG coupling. The line carrying the voltage v_AC can serve as a charging line 360. An advantage here is that, with a suitable high-voltage capacitor, this charging line 360 ​​is not a high-voltage line. This leads to simpler scalability of the voltage supply, allowing, for example, more feedthroughs to be accommodated in the same space. Fewer voltages would then need to be generated in a vacuum 921. However, this increases the circuit complexity in the vacuum, and the voltage v' might need to be stabilized. In Figure 12a, v_AC denotes an alternating voltage in the low-voltage range. In contrast, X_DC denotes a direct voltage in the high-voltage range.

[0114] Figure 12b schematically shows the introduction of a low voltage v into the vacuum 921 and the introduction of a high voltage X_DC into the vacuum 921. The voltage V can be configured as either a direct current (DC) or alternating current (AC). The voltage X_DC is always configured as a DC voltage. A complex circuit arrangement 910, shown only schematically, is located in the vacuum 921. This generates a variety of different output voltages in the high-voltage range.

[0115] Figure 13 schematically shows a high-voltage mounting of a multi-beam generator 205. The most important criteria for mounting the multi-beam generator 305 with its housing 350 at high voltage (HV) are electrical insulation, high-precision mechanical alignment, and, if necessary, mechanical readjustment without having to remove the multi-beam generator 305 / housing 350 from the multi-particle beam system 1. In the example shown in Figure 13, these points are achieved by means of a three-point mounting. The mounting itself is achieved by a corresponding connection between the second section 332 and the housing 350. Specifically, a ceramic ball 903 is arranged between the underside 352 of the housing 350 and the second section 332. This ceramic ball 903 is insulating.The ceramic ball 903 is positioned precisely, for example, by means of dimensionally accurate indentations in the second section 332 and / or on the underside 352 of the housing 350. The housing 350 is also screwed to the second section 332 using a screw 901. This screw 901 is insulated from the high voltage (HV) by a ceramic bushing 902. The screw connection of the housing 350 to the second section 332 provides at least a small degree of adjustment. This allows the filter plate 304 to be aligned with the incident particle jet 309. This is schematically indicated by the double arrows in Figure 13 between the first section 331 and the top 351 of the housing 350. Furthermore, the distance between the second section 332 and the underside 352 of the housing 350 can also be easily readjusted.This is also schematically indicated by the double arrows between the underside 352 and the second section 332 in Figure 13. Finally, the ceramic ball 903 is used to set the distance between the second section 332 and the first section 331 to a predetermined value; this is again illustrated by a double arrow.

[0116] Figure 14 schematically shows another mounting option for a multi-beam generator 305 at high voltage (HV). In the illustrated example, the multi-particle beam system 1, surrounding the housing 350 with the multi-aperture arrangement 304, 366, comprises an outer housing 909. This outer housing 909 is at a low-voltage potential, in this example, ground potential. The outer housing 909 comprises a top 912, a bottom 913, and a side wall 911. In the illustrated example, the housing 350 is suspended within the outer housing 909. However, the housing 350 could also be mounted differently within the outer housing 909. In the illustrated example, two suspensions 907 and 908 are shown. These can be implemented, for example, using a thin wire or a spring. At the end of the suspensions 907 and 908, there is a ceramic ball 903, 904, respectively.In the example shown, the ceramic ball 903 is clamped between a pipe clamp 905, which is at earth potential, and the housing 350 at high voltage (HV). Alternatively, corresponding recesses are provided in the side wall 911 of the outer housing 909 and / or the side wall 353 of the housing 350 for the appropriate positioning of the ceramic ball 903. The ceramic ball 904 is, in turn, clamped by means of a pipe clamp 906 and the other side wall 353 of the housing 350. In the example shown, there is no side wall of the outer housing 909 directly on this side. Instead, there is a free space 914. This allows the housing 350 to be removed from the outer housing 909 by removing the pipe clamp 906 and the ceramic ball 904. The direction of distance is schematically represented by the thick arrow next to the reference symbol 914.

[0117] Furthermore, it is of course possible to mount the housing 350 in the outer housing 909 on other sides (not shown in Figure 14) in a corresponding manner or in another way. Overall, the mounting options are numerous, and the two mounting options shown in Figures 13 and 14 are to be understood as examples. A multi-particle beam system is revealed that can operate with very high kinetic energies within the particle-optical column and yet enables very good single-beam shaping by means of a multi-beam generator. Required correction voltages in the area of ​​a multi-beam generator or the micro-optics are kept low by a clever design of the entire column. For this purpose, the voltages from a source or...Charged particles emitted from the emitter tip, initially with very high kinetic energy, are decelerated relatively strongly before reaching the multi-beam generator. They then pass through the multi-beam generator relatively slowly and are subsequently accelerated back to very high kinetic energies. This allows correction voltages within the multi-beam generator or within the micro-optics to be kept small in magnitude. The multi-beam generator or the micro-optics themselves are at a high-voltage potential. Large portions of the remaining particle-optical column can also be kept at a low-voltage potential, and in particular at ground potential, in the solution according to the invention.

[0118] Reference symbol list

[0119] 1. Multi-beam particle system, multi-beam particle microscope

[0120] 3 primary particle beams, first single-particle beams

[0121] 5 beam spots, points of impact

[0122] 7. Object, sample, wafer

[0123] 9 secondary particle beams, second single-particle beams

[0124] 10 Computer system, control

[0125] 15 Sample surface, wafer surface

[0126] 25 pixels of a second single-particle beam

[0127] 101 Object level

[0128] 102 lens

[0129] 103 Field lens

[0130] 105 axle

[0131] 111 Beam crossing (English: “Cross-Over”)

[0132] 200 detector system

[0133] 205 Projection lens system

[0134] 206 Projection lens

[0135] 207 Multi-particle detector

[0136] 208 Projection lens

[0137] 210 Projection lens

[0138] 212 Beam crossing

[0139] 214 aperture filter, contrast diaphragm, collective anti-deflection system

[0140] Beam generating device

[0141] Particle source

[0142] extractor

[0143] Collimation lens system

[0144] Multi-aperture array, filter plate

[0145] Multi-beam generator

[0146] Multi-aperture plate, multi-aperture array, multi-aperture corrector arrangement, field lens, aperture plate

[0147] Field lens

[0148] Particle beam

[0149] Intermediate image plane

[0150] Beam focus

[0151] Section

[0152] Section (first section)

[0153] Section (second section)

[0154] Imaging particle optics in the primary path

[0155] Housing

[0156] Top of the case

[0157] Underside of the case

[0158] side panel of the housing

[0159] Control electrode

[0160] Shielding electrode

[0161] Charging cable

[0162] Data line

[0163] Output line

[0164] Multi-aperture corrector arrangement

[0165] Beam switch, magnet arrangement

[0166] Scan distractor

[0167] Moving table or positioning device, power supply unit

[0168] application-specific integrated circuit (ASIC)

[0169] screw

[0170] Threaded bushing

[0171] ceramic ball

[0172] ceramic ball

[0173] Pipe clamp 906 Pipe clamp

[0174] 907 Suspension

[0175] 908 Suspension

[0176] 909 outer casing

[0177] 910 Circuit arrangement

[0178] 911 Side wall

[0179] 912 Top

[0180] 913 Underside

[0181] 914 free space

[0182] 920 air

[0183] 921 Vacuum

[0184] d1 diameter

[0185] d2 diameter

[0186] d3 diameter

[0187] d4 diameter

[0188] v Voltage

[0189] v' voltage

[0190] V2 Voltage (High-voltage voltage) A Voltage difference, Offset x direction

[0191] y direction

[0192] z direction

[0193] Z particle optical axis

Claims

Patent claims 1. A multi-particle beam system that has the following features: a particle source for emitting a charged particle beam, a multi-beam generator configured to generate a plurality of charged first single-particle beams from the charged particle beam, wherein the multi-beam generator has a multi-aperture arrangement with a filter plate, the filter plate being penetrated by the charged particle beam to form the plurality of first single-particle beams, a first particle optics with a first particle-optical beam path configured to image the first single-particle beams onto a sample surface of a sample; a sample table for arranging the sample; a voltage supply unit; and a control system for controlling the multiple particle beam system; wherein the control system is set up to provide a first high voltage V1 at the particle source by means of the voltage supply unit, wherein the control is set up to provide a first low voltage Vn1 by means of the voltage supply unit at a first section of the particle optical beam path, which is arranged in front of the multi-aperture arrangement with respect to the particle optical beam path, wherein the control is set up to provide a second high voltage V2 by means of the voltage supply unit at the multi-aperture arrangement, wherein the control is set up to provide a second low voltage Vn2 to a second section of the particle optical beam path, which is arranged downstream of the multi-aperture arrangement with respect to the particle optical beam path, by means of the voltage supply unit, and wherein the control is set up to provide a third high voltage V3 to the sample stage and thus to the sample by means of the voltage supply unit, wherein the first high voltage V1, the second high voltage V2 and the third high voltage V3 have the same sign.

2. Multiple particle beam system according to claim 1, where the following relation applies to the magnitude of a potential reduction AV1 caused between the first section and the multi-aperture arrangement: AV1 > 5 kV, in particular AV1 > 10 kV or AV1 > 20 kV; and / or 35 where the following relation applies to the magnitude of the potential increase AV2 between the multi-aperture arrangement and the second section: AV2 > 5kV, in particular AV2 > 10kV or AV2 > 20kV.

3. A multiple particle beam system according to one of the preceding claims, wherein the first high voltage V1 at the particle source satisfies the following relation in magnitude: 25 kV < V1, in particular 30 kV < V1 or 40 kV < V1; and where the third high voltage V3 at the sample table satisfies the following relation in terms of magnitude: 25kV < V3, in particular 30kV < V3 or 40kV < V3.

4. A multi-particle beam system according to one of the preceding claims, wherein the first low voltage Vn1 at the first section satisfies the following relation in magnitude: OV < Vn1 < 100V, in particular Vn1 = 0V, and where the second low voltage Vn2 at the second section satisfies the following relation in terms of magnitude: 0V < Vn1 < 100V, in particular Vn2 = 0V.

5. Multi-particle beam system according to any one of the preceding claims, wherein the multi-aperture arrangement comprises a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams.

6. Multi-particle beam system according to one of the preceding claims, wherein the multi-beam generator has a housing, and the multi-aperture arrangement is located in the housing.

7. Multi-particle beam system according to the preceding claim, where the housing and the filter plate are at the same potential.

8. Multi-particle beam system according to the preceding claim, the second high voltage V2 is applied to the housing and the filter plate.

9. Multi-particle beam system according to any one of claims 6 to 8, wherein the first section has a first aperture plate with an aperture central with respect to the particle-optical beam path, and / or wherein the second section has a second aperture plate with an aperture central with respect to the particle-optical beam path.

10. Multi-particle beam system according to the preceding claim, wherein the housing has, on the particle source side, a top surface with an aperture central with respect to the particle-optical beam path as an inlet opening for the charged particle beam into the housing, and wherein the central aperture of the top surface is dimensioned such that it is not larger than the central aperture of the first aperture plate.

11. Multiple particle beam system according to the preceding claim, wherein a shielding electrode or several shielding electrodes are arranged in the area of ​​the central aperture of the top of the housing.

12. Multiple particle beam system according to one of claims 9 to 11, wherein the housing has a bottom side on the sample side with a central aperture, relative to the particle-optical beam path, as an exit opening for the first single-particle beams, and wherein the central aperture of the underside is dimensioned such that it is not larger than the central aperture of the second aperture plate.

13. Multi-particle beam system according to one of claims 9 to 11, wherein the housing has a bottom side on the sample side with a multi-aperture arrangement central with respect to the particle-optical beam path, through which the first single-particle beams emerge from the housing.

14. Multi-particle beam system according to claim 12 or 13, wherein a control electrode with a central aperture relative to the particle-optical beam path is arranged between the housing and the second aperture plate, wherein the control is set up to individually provide a control voltage at the control electrode by means of the voltage supply unit, so that a distance between the first individual particle beams relative to each other can be adjusted.

15. Multi-particle beam system according to any one of claims 6 to 14, wherein the multi-aperture arrangement includes a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams; and wherein an application-specific integrated circuit (ASIC) for controlling the multi-aperture correction arrangement is arranged in the housing.

16. Multi-particle beam system according to any one of claims 6 to 15, wherein the voltage supply unit is configured to generate at least one reference voltage Vref in the high-voltage range and at least one control voltage Vc different from the reference voltage, and where the difference AVref between the reference voltage Vref and the control voltage Vc satisfies the following relation in terms of magnitude: OV < AVref < 200V, in particular 0V < AVref < 150V or OV < AVref < 100V.

17. Multi-particle beam system according to any one of claims 6 to 16, wherein the multi-aperture arrangement includes a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams; wherein a circuit is arranged in the housing which is configured to generate a larger number k>n of voltages from a number n of voltages, wherein the n voltages are brought into the housing from outside, and wherein the k voltages are used to control the multi-aperture corrector.

18. Multi-particle beam system according to any one of claims 6 to 17, wherein the voltage supply unit is multi-part and includes an inner voltage supply unit which is arranged inside the housing.

19. Multiple particle beam system according to claim 18, the internal voltage supply unit includes a rechargeable battery.

20. Multi-particle beam system according to any one of claims 6 to 19, wherein the multi-aperture arrangement includes a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams; wherein a data line for providing control data for the multi-aperture corrector arrangement is led into the housing from the outside.

21. Multiple particle beam system according to any one of claims 6 to 19, wherein the multi-aperture arrangement includes a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams;38 where control data for the multi-aperture corrector arrangement is provided wirelessly from outside into the housing.

22. Multi-particle beam system according to the preceding claim, The provision of control data from the outside into the housing is carried out in one of the following ways: optically, by means of infrared signals and / or by means of radio signals.

23. Multi-particle beam system according to any one of claims 6 to 22, wherein the housing is electrically insulated relative to the first section and the second section; and / or the housing is adjustable relative to the first section and / or the second section.

24. A multi-particle beam system according to any one of the preceding claims, wherein the multi-aperture arrangement comprises a multi-aperture corrector arrangement configured to perform individual correction of the generated first single-particle beams; and wherein the multi-aperture corrector arrangement is configured to perform at least one of the following corrections individually for each of the single-particle beams: a deflection, a stigmatization, a focal length change.

25. Multi-particle beam system according to one of the preceding claims, wherein the multi-particle beam system is a multi-beam particle microscope.

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