Particle beam system, method of operating a particle beam system and computer program product

Abstract

The invention relates to a particle beam system, in particular a multi-beam particle microscope, comprising a multi-beam deflection device and comprising a beam stop, and to related methods for operating a particle beam system and to related computer program products. In this case, the multi-beam deflection device is arranged in a particle optical beam path of the particle beam system downstream of a multi-beam generator and upstream of a beam switch. The multi-beam deflection device is used for collective blanking of a plurality of individual particle beams which impinge on a beam stop which is arranged in the particle optical beam path level with a location at which the particle beam diameter is reduced or is at a minimum. By way of example, these locations are cross-planes of the individual particle beams or intermediate image planes.

Description

TECHNICAL FIELD

[0001] The present invention relates to a particle beam system operated with a plurality of particle beams. BACKGROUND

[0002] Just like a single-beam particle microscope, a multi-beam particle microscope can be used for analyzing an object on a microscopic scale. For example, these particle microscopes can be used to record an image of an object representing a surface of an object. In this way, the structure of the surface can be analyzed, for example. In a single-beam particle microscope, a single beam of charged particles, such as electrons, positrons, mesons or ions, is used to analyze an object, whereas in a multi-beam particle microscope, a plurality of particle beams is used for this purpose. The plurality of particle beams, also referred to as a bundle, is directed simultaneously to the surface of the object, as a result of which a significantly larger area of the surface of the object can be sampled and analyzed compared to using a single-beam particle microscope within the same period of time.

[0003] WO 2005 / 024 881 A2 discloses a multi-particle beam system in the form of an electron microscope system which operates using a plurality of electron beams to scan an object to be examined using parallel electron beam bundles. The electron beam bundles are generated by directing an electron beam generated by an electron source onto a multi-aperture plate having a plurality of openings. Part of the electrons of the electron beam hit the multi-aperture plate and are absorbed there, while another part of the beam passes through the openings in the multi-aperture plate so that the electron beam is shaped in the beam path downstream of each opening, the cross section of the electron beam being defined by the cross section of the opening. Furthermore, a suitably chosen electric field arranged in the beam path upstream and / or downstream of the multi-aperture plate has the effect that each opening in the multi-aperture plate acts as a lens on the electron beam passing through the opening so that the electron beam is focused on a plane at a distance from the multi-aperture plate. The plane in which the focus of the electron beam is formed is imaged by a downstream optical unit onto the surface of the object to be examined so that the individual electron beams hit the object as primary beams in a focused manner. They generate there interaction products, such as backscattered electrons or secondary electrons, which are emitted from the object, which are shaped to form secondary beams and are directed by a further optical unit onto a detector. Each secondary beam hits a separate detector element there so that the electron intensity detected by the detector element provides information about the object at the position of the object where the corresponding primary beam hit the object. The bundle of primary beams is systematically scanned over the surface of the object to produce an electron micrograph of the object in a manner customary for scanning electron microscopes.

[0004] In the described multi-particle beam system, high resolution is of high relevance for a satisfactory and successful use in practice. The resolution of a particle beam system is usually limited by the scanning grid of the individual pixels or the dwell time on each pixel on the sample and by the particle beam diameter. In order to observe as precisely as possible a specific dwell time on each pixel on the sample or a specific scanning grid, it is necessary to precisely control the scanning particle beam and it can be desirable to briefly interrupt the incidence of the particle beam on the sample in a targeted manner, for example in the case of a jump line during scanning or in the case of a movement of the sample stage in order to scan a different sample area.

[0005] In principle, the use of a deflection device in combination with a beam stopper is known for the interruption of such particle beams (so-called "blanking") or the interruption of the incidence of the particle beam on the object. Corresponding configurations for single-beam particle microscopes are found, for example, in US 8,759,796 B2 and US 2018 / 0151327 A1. The particle beam is deflected by means of a charged deflection plate and a simple diaphragm is used as a beam stopper. Since the beam diameter of the single particle beam is small compared to the beam tube diameter of a single-beam particle microscope, the diaphragm can in principle be positioned as required within the particle-optical unit.

[0006] Due to space reasons, this design freedom does not exist in multi-particle beam systems, since the beam array has a relatively large diameter compared to the beam tube in the case of a multi-beam particle system. Therefore, the deflection device in a multi-particle beam system, in particular in a multi-beam particle microscope, is configured near the cathode and the associated beam stopper is configured near the anode, thus still upstream of the multi-beam generator for generating a plurality of individual particle beams from a single particle beam. This standard configuration, however, leads to unwanted charges near the multi-beam generator in a multi-particle beam system, which is used to generate a plurality of individual particle beams from a single particle beam. These charges are disadvantageous and either impede the illumination of the multi-beam generator to be as uniform as possible or lead to a lens effect of the apertures in the multi-aperture plate of the multi-beam generator being impaired. In the worst case, this leads to image distortions. SUMMARY

[0007] It is therefore an object of the present application to propose an improved particle beam system, in particular a multi-beam particle microscope, which comprises a deflection device and a beam stopper, which solves the above-mentioned problems.

[0008] This object is solved by the following. Advantageous embodiments of the present application are apparent from the following.

[0009] The present application claims priority from German patent application No. 10 2019 008 249.4, the disclosure of which is incorporated herein by reference in its entirety.

[0010] Herein, the application is based on the following basic considerations: First, a multi-beam deflection device is used according to the application for jointly deflecting the plurality of charged first individual particle beams. Thus, first a plurality of individual particle beams is generated, and the selective masking or deflection by the multi-beam deflection device is only subsequently carried out in a collective manner. Thus, as seen from the direction of propagation of the particle beams and with respect to the particle-optical beam path, the deflection device according to the application is only arranged downstream of a multi-beam generator which first generates a plurality of individual particle beams. This avoids unwanted charging of the multi-beam generator. Second, the clever arrangement of the beam stop in the particle-optical beam path takes into account the limited spatial conditions in a multi-particle beam system. This is because the beam stop is arranged flush with a location at which the particle beam diameter is reduced or is at a minimum. In this case, this can be, for example, the location of a crossover or an intermediate image. The application will be explained in more detail below:

[0011] According to a first aspect of the application, the application relates to a particle beam system, more particularly to a multi-beam particle microscope, comprising the following:

[0012] at least one particle source which is configured to generate a charged particle beam;

[0013] a first particle-optical unit having a first particle-optical beam path, the particle-optical unit being configured to generate a plurality of individual particle beams and to image the individual particle beams on an object plane; and

[0014] a second particle-optical unit which is configured to image a plurality of second individual particle beams which emanate from an entry point in the object plane onto a detector unit;

[0015] wherein the particle beam system further comprises the following:

[0016] a multi-beam generator which is configured to generate a plurality of charged first individual particle beams from the charged particle beam;

[0017] an objective, wherein the individual particle beams substantially pass through the objective, and the objective is configured to guide the first individual particle beams at the object plane such that the first individual particle beams impinge on the object plane at a plurality of entry points;

[0018] a beam switch which is arranged in the first particle-optical beam path between the multi-beam generator and the objective and which is arranged in the second particle-optical beam path between the objective and the detector unit, the first particle-optical beam path and the second particle-optical beam path branching within the beam switch;

[0019] a beam stop; and

[0020] a multi-beam deflection device having a controller,

[0021] wherein the multi-beam deflection device is arranged in the first particle-optical beam path downstream of the multi-beam generator and upstream of the beam switch,

[0022] wherein the controller is configured to temporarily co-deflect the first individual particle beams by means of the multi-beam deflection device such that the first individual particle beams are substantially incident on the beam stop, and thus not on the object plane, and

[0023] wherein the beam stop is arranged in the first particle optical beam path level with a location where the particle beam diameter is reduced or is at a minimum.

[0024] The charged particles can for example be electrons, positrons, muons or ions or other particles. Preferably, the charged particles are electrons generated for example using a thermal field emission source (TFE). However, other particle sources can also be used.

[0025] In principle, multi-beam generators are known in the prior art. For example, a multi-beam generator can comprise a multi-lens array consisting of a multi-aperture plate and a corresponding electrode. Alternatively, a multi-beam generator can comprise a multi-aperture plate and a multi-deflector array. The two multi-beam generators differ in the way the plurality of charged first individual particle beams is generated; in particular, a real intermediate image occurs when using a multi-lens array, whereas a virtual intermediate image can occur when using a multi-deflector array. The present invention can be used in combination with both variants of the described multi-beam generators, but other multi-beam generator configurations are possible.

[0026] The particle optical objective can be a magnetic lens or an electrostatic lens or a combined magnetic / electrostatic lens.

[0027] The multi-beam deflection device is arranged in the first particle optical beam path downstream of the multi-beam generator and upstream of the beam switch, thus between the multi-beam generator and the beam switch, in the propagation direction of the particle beam. This prevents adverse charging of the multi-beam generator during the masking process. Furthermore, the multi-beam deflection device is configured to act on all first individual particle beams with the same deflection field. Thus, no separate deflection device is provided for the individual individual particle beams. Rather, the deflection of the individual particle beams is achieved collectively with the aid of the multi-beam deflection device.

[0028] The controller of the multi-beam deflection device is configured to temporarily deflect the first individual particle beams by means of the multi-beam deflection device such that the first individual particle beams are substantially incident on the beam stop and thus not on the object plane. The controller can be a separate controller for the multi-beam deflection device. The controller of the multi-beam deflection device can also be integrated in the controller of the entire system, i.e. in the controller of the entire particle beam system. The controller controls the masking procedure. Here, the deflection of the first individual particle beams obtained is achieved temporarily, thus not permanently. The temporary deflection can be achieved in a time interval type manner and the deflection time intervals each have the same length. However, the time intervals can also differ. Advantageous modes of operation will be described further below in this patent application.

[0029] Furthermore, according to the application, the beam stop is arranged in the first particle optical beam path level with a position at which the particle beam diameter is reduced or is at a minimum. This takes into account the limited space conditions in the multi-particle beam system. The particular reduced or minimum particle beam diameter can relate to the respective particle beam diameter of the individual particle beams. However, alternatively, this can also relate to the overall particle beam diameter which is formed by the totality of the individual particle beams and thus by the particle beam array or the individual particle beamlets. When reference is made to the position at which the particle beam diameter is reduced or is at a minimum, reference is made to the particle optical beam path without deflection caused by the multi-beam deflection device, but with the individual particle beams being incident on the object plane. Thus, in the case of deactivation of the multi-beam deflection device, the beam stop is also not located at the position at which the particle beam diameter is reduced or is at a minimum; rather, in the case of deflection of the individual particle beams by the multi-beam deflection device, the beam stop is located at the same level as this position, at the position at which the individual particle beams impinge.

[0030] According to a preferred embodiment of the application, the first particle optical beam path has a crossing plane of the individual particle beams upstream of the objective, and the beam stop is arranged in the first particle optical beam path level with the crossing plane. The first individual particle beams cross one another in this crossing plane, and thus the particle beam diameter of the entire particle beam array is at a minimum or at least reduced here. The first individual particle beams are as close to one another as possible in the crossing point. Typically, the common cross section of all individual particle beams, i.e. of the individual particle beamlets, is approximately 25 μιη to 200 μιη in the crossing plane. Thus, even in the case of limited space conditions in the multi-beam particle beam system, the beam stop can be arranged level with this crossing. Furthermore, a skilled arrangement and actuation of the multi-beam deflection device makes it possible to deflect the individual particle beamlets at the beam stop with likewise very small particle beam diameters. Thus, it is possible to implement the beam stop in a manner which is as small and space-saving as possible. According to an embodiment of the application, the crossing plane is arranged between the beam switch and the objective.

[0031] According to a preferred embodiment of the present application, the beam stop is arranged in the first particle optical beam path substantially in level with the upper focal plane of the objective lens facing the multi-beam generator. In this plane, the diameter of the individual particle beams is smallest. Preferably, the upper focal plane of the objective lens corresponds to the cross-over plane of the crossing individual particle beams. This arrangement also allows for a telecentric incidence of the individual particle beams on the object plane or on a sample located there.

[0032] According to a preferred embodiment of the present application, the multi-beam deflection device is arranged and / or controlled such that the individual particle beams deflected by the multi-beam deflection device substantially experience a parallel shift in the cross-over plane and / or in the upper focal plane of the objective lens. Here, the multi-beam deflection device can be arranged near the intermediate image. It is also possible to combine the multi-beam deflection device with a field lens system. The field lens system comprises at least one field lens; it can also be a field lens system with two, three, four or more field lenses.

[0033] A parallel shift in the cross-over plane (according to which the position of incidence in the cross-over plane changes, but the direction of the individual particle beams in the cross-over plane does not change) leads to the fact that the particle beam diameter of the deflected or shielded individual particle beams is also reduced or minimized. Therefore, a beam stop arranged in level with the cross-over point or in the cross-over plane can have a correspondingly smaller size or beam capture area. A parallel shift in the upper focal plane of the objective lens is advantageous because the position of incidence of the individual particle beams on the object plane or the sample does not change during the shift of the individual particle beams (precisely up to the point at which the deflected individual particle beams are deflected to the extent that they no longer pass through the objective lens but are incident on the beam stop). Therefore, here an observable activation and deactivation of the individual particle beams can be achieved very quickly and abruptly without the individual particle beams passing through the object.

[0034] According to a preferred embodiment of the present application, the beam stop comprises a cup. Thus, the beam diaphragm is not a diaphragm here having a substantially flat surface or an impact surface for the particle beams; rather, the beam stop has a predefined depth or cavity into which the deflected individual particle beams are deflected in order to be captured or absorbed there. The use of a beam stop having a certain depth ensures a more efficient and, in particular, more targeted and more defined beam capture compared to the case of a beam stop having a flat surface. At the point of incidence of the deflected beams, further charged contaminants can form. By using a beam stop having a certain recess at the point of incidence, these charges can be isolated from the other beams that pass through the cup without deflection. If the beam stop is correspondingly deep and narrow and if the direction of incidence of the particle beams to be absorbed therein is correspondingly controlled, it is possible to prevent these reflected individual particle beams from re-emerging from the beam stop in an uncontrolled and very divergent manner, even in the case of reflections of individual particle beams. Thus, secondary electrons cannot emerge from the beam stop in an uncontrolled and very divergent manner either. Furthermore, the charges in the entry area are largely avoided in the case of a targeted entry into the beam stop. Here, the cup can have different designs. For example, the depth of the cup can be greater than 1 cm, in particular at least 1.5 cm.

[0035] According to a preferred embodiment of the present application, the cup is substantially rotationally symmetrical with respect to the optical axis of the particle beam system. This allows for a deflection and absorption of individual particle beams in different directions.

[0036] According to a preferred embodiment of the present application, the cup has a passage opening along its longitudinal axis, and a groove having a substantially annular cross section for beam capture is arranged around the passage opening. Here, the cup is configured such that the optical axis of the particle beam system, in particular, extends along the longitudinal axis of the cup through the passage opening of the cup. Thus, in this embodiment of the beam stop, individual particle beams that are not deflected by the multi-beam deflection device pass substantially undisturbed through the passage opening of the cup. Conversely, if the multi-beam deflection device is activated, the individual particle beams are deflected into the annular groove. Here, the annular groove preferably has a continuous circumference, such that the individual particle beams can be deflected in any direction around the optical axis of the system and turned into the groove. Thus, by skilled control of the multi-beam deflection device, the entire annular groove can be temporarily used for beam capture, and thus the resulting charge distribution or charging distribution is in the entire annular groove, not only limited to a few points of the groove.

[0037] According to a preferred embodiment of the application, the bundle entry opening of the annular groove has a sharp edge on the inner ring, wherein a surface is provided which is inclined with respect to the longitudinal axis of the cup and which extends away from the longitudinal axis from this sharp edge into the groove. The provision of the sharp edge ensures that there is little area in the region of the bundle entry opening for charging the bundle stopper. The conical surface aligned as described above and starting from this sharp edge helps to reflect the individual particle bundles into the annular groove even in the event of a deflection occurring on the cup edge. This increases the efficiency of the bundle stopper.

[0038] According to a further preferred embodiment of the application, the diameter of the passage opening in the bundle entry region increases starting from the bundle entry opening of the passage opening. Here, the bundle entry region denotes the upper region of the cup facing the multi-beam deflection device and its passage opening in the installed state. The change in the diameter of the passage opening can be achieved, for example, by means of an undercut. The diameter of the passage opening can be essentially constant in the direction of the particle-optical beam path below the bundle entry opening. The described change in the diameter in the upper region ensures that the individual particle bundles passing through the cup do not come into contact with the inner wall of the inner tube or the passage opening, but rather maintain the required minimum distance from the inner wall of the passage opening.

[0039] According to a preferred embodiment of the application, an absorber material is arranged at the bottom of the annular groove. This material is, for example, a material having a low backscattering coefficient for particle bundles incident thereon. Preferably, these are materials having a low atomic number, such as carbon, aluminum, beryllium, etc. In addition, the choice of material should be such that, in the event of an incident particle, secondary electrons are not generated, if possible.

[0040] According to a preferred embodiment of the application, the cup is at least partially embedded in the objective, in particular screw-embedded, and / or the cup can be exchanged by means of an exchange tool. To this end, a thread for screwing the cup into the objective can be provided on the lower part of the cup, opposite the bundle entry opening. The particle-optical objective of a particle beam system usually comprises an upper (source-side) pole piece and a lower (object-side) pole piece. Both pole pieces have a pole piece aperture which coincides with the optical axis of the objective. A beam tube, which is internally evacuated, can extend through the pole piece aperture of the upper pole piece. Here, the upper pole piece is usually not flat, but rather has a form which has an embodiment of a funnel shape, and is preferably at ground potential. The bundle stopper or cup can now be wholly or partially embedded in the pole piece aperture of the upper pole piece. Preferably, this embedding in the beam tube is effected within the objective. The pole pieces of the objective are relatively easily accessible. They can be reached through the sample chamber in order to install or, if necessary, exchange the bundle stopper. Although the sample chamber needs to be vented during such an exchange process, it is not necessary to break the high vacuum of the remainder of the particle beam system for this purpose. Embedding the cup in the objective thus ensures that a possible exchange procedure of the cup can be carried out very quickly. Preferably, the cup is non-magnetic; this is advantageous if the objective is a magnetic objective.

[0041] According to a preferred embodiment of the present application, the distance between the multi-beam deflection device and the beam stop is at least 20 cm, preferably at least 30 cm. This length specification relates to the minimum distance between the multi-beam deflection device and the beam stop, since the components themselves also have a spatial extent. The measurement is made along the optical axis of the system. In this case, a drift path of at least 20 cm, preferably at least 30 cm, is relatively long. This is advantageous, since only a relatively low voltage is required for the deflection of the individual particle beams. The voltage is typically less than 100 V. If the drift path were shorter, i.e. the distance were shorter, a stronger electric field would have to be used to deflect the individual particle beams; if the drift path were only a few centimeters, the required voltage would be in the range of 1 kV. However, it is preferable to work at low voltages. By way of example, if the beam stop is configured in the first particle-optical beam path flush with the intersection plane between the beam switch and the objective lens, the drift path between the multi-beam deflection device and the beam stop is at least 20 cm, preferably at least 30 cm.

[0042] According to an alternative embodiment of the present application, the beam stop is configured in the first particle-optical beam path downstream of the multi-beam generator and upstream of the beam switch flush with the intermediate image plane. In this case, the drift path is significantly shorter compared to the solution described above, but the absolute deflection required is also smaller. In this configuration of the beam stop, there are also cases in which the beam stop is configured in the first particle-optical beam path flush with a location at which the particle beam diameter is reduced or is at a minimum. By way of example, the intermediate image of the multi-beam source occurs in the region of a field lens system, wherein the focus of the individual particle beams passing through the multi-beam generator can be considered to be the respective source of the multi-source. However, even without a field lens system, an intermediate image can be produced between the multi-beam generator and the beam switch.

[0043] According to a preferred embodiment of the present application, the beam stop configured in the first particle-optical beam path flush with the intermediate image plane comprises an aperture array. This array comprises a plurality of openings through which the first individual particle beam can pass as long as the multi-beam deflection is not performing a beam deflection. Conversely, if the multi-beam deflection is activated or in operation, the incident position of the individual particle beam on the aperture array in the intermediate image plane is displaced, and the individual particle beam thus impinges on the array or the multi-aperture. Here, the incident positions of the individual particle beams are different from one another. In this respect, this embodiment variant is thus also different from the embodiment variant described above, according to which the beam stop is configured flush with the intersection plane of the plurality of individual particle beams.

[0044] According to a preferred embodiment of the invention, the multi-beam deflection device includes deflecting plates. For example, these deflecting plates may be configured in pairs. Preferably, the multi-beam deflection device includes a pair of deflecting plates that deflect individual particle beams together. It is also possible to provide multiple pairs of deflecting plates in the multi-beam deflection device that deflect individual particle beams together. For example, two pairs of deflecting plates may be provided, configured horizontally relative to the particle optical beam path but rotated 90° relative to each other. This creates variability in one or more deflection directions generated by the multi-beam deflection device. The deflecting plates are preferably electrostatic deflecting plates that facilitate rapid deflection. However, it is also possible to use magnetic deflection devices.

[0045] According to another preferred embodiment of the invention, the multi-beam deflection device has multiple stages. In this case, multiple pairs of deflection plates may also be provided; however, they are configured at different positions or different levels relative to the particle optical beam path. Regarding the particle optical beam path, for example, the various stages of the multi-beam deflection device may be configured sequentially. Here, other components of the particle optical unit may also be located between the various stages of the multi-beam deflection device. However, the stages of the multi-beam deflection device may also directly follow each other. The advantage of providing a second stage or another stage for the multi-beam deflection device is that the deflection of the multi-beam deflection device can be set very precisely. Furthermore, the second stage provides additional degrees of freedom, which can, for example, be used to again set the incidence of individual particle beams in the object plane differently.

[0046] According to a preferred embodiment of the invention, the multi-beam deflection device is configured such that individual particle beams can be deflected in different deflection directions. For example, this can be achieved using a pair of deflecting plates, provided the electric field direction between the two plates is reversible. Additional pairs of deflecting plates or other configurations for the multi-beam deflection device also allow individual particle beams to be deflected in different deflection directions. This is advantageous because, provided it cannot be avoided under any circumstances, the charge on the beam terminator not only accumulates at certain locations but can also be better distributed.

[0047] According to a second aspect of the invention, this second aspect relates to a method for operating a particle beam system, particularly a method for operating a particle beam system as described in the various embodiments above. According to the invention, the method comprises the following steps:

[0048] -The object is scanned in the first row by means of the first separate particle beam;

[0049] -The object is scanned in the second row using the first separate particle beam; and

[0050] -According to the first setting of the multi-beam deflection device, during the jump from the first line to the second line, the particle beam is deflected by means of the multi-beam deflection device.

[0051] Here, the first setting of the multi-beam deflection device characterizes the deflection direction and the deflection power resulting therefrom. By way of example, the first setting of the multi-beam deflection device corresponds to the electric field applied to the multi-beam deflection which leads to the described effect.

[0052] Thus, according to the application, the individual particle beams are deflected or shielded during the transition from the first row to the second row. This thus relates to shielding during the jump. During such a jump, the individual particle beams would impinge on the object in an uncontrolled manner or pass over the object without a shielding procedure. This would lead to a charging on the object which reduces the resolution of the particle beam system. It is therefore advantageous to suppress the impingement of the individual particle beams on the object during the jump.

[0053] According to a further preferred embodiment of the application, the method further comprises the following steps:

[0054] - scanning the object by means of the individual particle beams in a third row;

[0055] - deflecting the individual particle beams by means of the multi-beam deflection device during a jump from the second row to the third row in accordance with a second setting of the multi-beam deflection device.

[0056] Here, the second setting of the multi-beam deflection device is different from the first setting of the multi-beam deflection device. By way of example, the strength of the electric field applied to the multi-beam deflection device can be changed. It is also possible that not the strength but the direction of the electric field is changed, thereby changing the deflection direction. A combination of a change in the field strength and a change in the field direction is also possible. Different activation components of the multi-beam deflection device, in particular plates or plate pairs, can also characterize different settings. The change in the setting of the multi-beam deflection device ensures that residual charges which inevitably occur on the beam stop do not accumulate at specific locations.

[0057] According to a preferred embodiment of the application, the different settings of the multi-beam deflection device are selected randomly. This random selection can be based on a random method or a pseudo-random method. What is achieved in both cases is that when the multi-beam deflection device is activated, the impingement position of the individual particle beams on the beam stop changes and an unwanted accumulation of charges and / or an unwanted symmetrical distribution of charges on the beam stop does not occur.

[0058] According to a third aspect of the application, the third aspect relates to a method for operating a particle beam system, in particular the particle beam system described in the foregoing in various embodiments. The method comprises the following steps:

[0059] - scanning a first region of the object by means of a first individual particle beam;

[0060] - scanning a second region of the object by means of a second individual particle beam; and

[0061] - depending on at least a first setting of the multi-beam deflection device, deflecting the individual particle beams by means of the multi-beam deflection device during a change of the region from the first region to the second region.

[0062] Thus, this embodiment variant does not involve a masking during a line change of the scanning individual particle beams; rather, this preferably involves an image change: the image generated by means of the particle beam system is generally composed of various individual images. Here, a single individual particle beam passes through a so-called single field of view (sFOV), and a plurality of individual particle beams, i.e. a beam of individual particle beams, correspondingly passes through a multi field of view (mFOV). The overall image is then composed of various multi fields of view or multi images. A small pause occurs during an image change or a change of the region between two multi fields of view, during which the individual particle beams should not be used to scan or probe the object. Thus, a masking of the individual particle beams is carried out during this change of the region. The pause required during a change of the region is generally longer than the pause during a line change of the individual particle beams during the generation of their respective individual images. Thus, the strategy for driving the multi-beam deflection device during a change of the region can also differ from the strategy during a line change. The risk of charging during the longer masking time is correspondingly greater, so that particular attention should be paid to changing the incidence position of the individual particle beams on the beam stop during a change of the region. According to a preferred embodiment of the present application, different settings of the multi-beam deflection device are used in an alternating manner during a change of the region. For example, it is possible to alternate between 2, 3, 4, 5 or more settings, for example in the sequence 1-2-1-2-1-2 or 1-2-3-4-5-1-2-3-4-5-1-2-3-4-5...

[0063] According to a further preferred embodiment of the present application, different settings of the multi-beam deflection device are selected and used at random. Here, a random method or a pseudo-random method can again be used to switch between the various settings of the multi-beam deflection device. Here, the multi-beam deflection device is preferably always active during a change of the region, and the individual particle beams are preferably never passed through the multi-beam deflection device without deflection and never incident on the object.

[0064] According to a preferred embodiment of the method of the present application, the rotationally symmetrical cup acts as a beam stop, which has a passage opening along its longitudinal axis, wherein a groove for beam capture having a circular cross section is arranged around the passage opening; and

[0065] wherein the circular groove for beam capture is passed through by the setting of the multi-beam deflection device.

[0066] According to this embodiment variant of the application, therefore, the individual particle beams are captured or absorbed along the entire groove of the cup. This ensures a uniform and rotationally symmetrical charge distribution in the cup. In the range of the generated charges, these charges are approximately rotationally symmetrical and have significantly less disturbing effect on the particle beams passing through the passage opening of the cup along the optical axis. Moreover, when the cup is arranged in the intersection plane of the individual particle beams, these individual particle beams are close to or overlap one another, so that, in principle, the influence of the charge distribution on the individual particle beams is the same for each individual particle beam.

[0067] According to a fourth aspect of the application, the fourth aspect relates to a computer program product having program code for carrying out the method as described in more detail before in various embodiment variants according to the second and third aspects of the application. The program code can be subdivided into one or more partial codes. Any conventional programming language can be used as the programming language.

[0068] The above-mentioned embodiment variants of the application can be combined with one another in whole or in part, as long as no technical contradictions result. The same applies to the mutual combination of the features according to the first, second, third and fourth aspects of the application. BRIEF DESCRIPTION OF DRAWINGS

[0069] The application will be better understood with reference to the accompanying drawings. In the drawings:

[0070] Figure 1 A schematic diagram of a particle beam system in the form of a multi-beam particle microscope is shown;

[0071] Figure 2 A particle beam system is schematically shown, which comprises a multi-beam deflection device and comprises a beam stop in the region of the intersection plane of the individual particle beams;

[0072] Figure 3 A particle beam system is schematically shown, which comprises a multi-beam deflection device and comprises a beam stop in the region of the intermediate image;

[0073] Figure 4 A configuration of a cup-shaped beam stop within an objective lens is schematically shown;

[0074] Figure 5 The structure of a cup-shaped beam stop is schematically shown in a sectional view and in a 3D view;

[0075] Figure 6 The structure of a further cup-shaped beam stop is schematically shown in a sectional view;

[0076] Figure 7 The effects of three different settings of the multi-beam deflection device are shown when particle beams are incident on the beam stop; and

[0077] Figure 8 Possible adjustments of the multi-beam deflection device in combination with a cup-shaped beam stop are shown. DETAILED DESCRIPTION

[0078] Figure 1 is a schematic representation of a particle beam system 1 in the form of a multi-beam particle microscope 1 which uses a plurality of particle beams. The particle beam system 1 generates a plurality of particle beams which impinge on an object to be examined in order to generate interaction products, such as secondary electrons, at the location which emanate from the object and are subsequently detected. The particle beam system 1 is of the scanning electron microscope (SEM) type which uses a plurality of primary particle beams 3 which are incident on the surface of an object 7 at a plurality of locations 5 and generate a plurality of electron beam spots or spots in the first plane 101 (object plane) of the objective system 100 which are spatially separated from one another. The object 7 to be examined can be of any desired type, for example a semiconductor wafer or a biological sample, and can comprise an arrangement of miniaturized elements etc. The surface of the object 7 is arranged in the object plane 101 of the objective 102 of the objective system 100.

[0079] Figure 1 An enlarged excerpt II in Fig. 1 shows a plan view of the object plane 101 with the regular rectangular field 103 of the locations of incidence 5 formed in the first plane 101. The locations of incidence 5 are arranged in a regular pattern in the field 103. Figure 1 In Fig. 1 the number of locations of incidence is 25 which form a 5x5 field 103. The number 25 of locations of incidence is a number chosen for reasons of simplification of the drawing. In practice, a significantly larger number of beams and thus a larger number of locations of incidence can be chosen, for example 20x30, 100x100 etc.

[0080] In the embodiment shown, the field 103 of locations of incidence 5 is essentially a regular rectangular field with a constant spacing P1 between adjacent locations of incidence. Example values for the spacing P1 are 1 micron, 10 microns and 40 microns. However, the field 103 can also have other symmetries, for example hexagonal symmetry.

[0081] The diameter of the beam spots shaped in the first plane 101 can be small. Example values for this diameter are 1 nanometer, 5 nanometers, 10 nanometers, 100 nanometers and 200 nanometers. The particle beams 3 are focused by the objective system 100 to shape the beam spots 5.

[0082] The primary particles of the impinging object generate interaction products, such as secondary electrons, backscattered electrons, or primary particles that have undergone a reversal of motion for other reasons, which emanate from the surface of the object 7 or from the first plane 101. The interaction products emanating from the surface of the object 7 are shaped by the objective 102 to form the secondary particle beams 9. The particle beam system 1 provides a particle beam path 11 for guiding the plurality of secondary particle beams 9 to a detector system 200. The detector system 200 comprises a particle-optical unit having a projection lens 205 for guiding the secondary particle beams 9 onto a particle multi-detector 209.

[0083] Figure 1 Excerpt I2 in Fig. 2 shows a plan view of the plane 211 in which the individual detection areas of the particle multi-detector 209 are located, onto which the secondary particle beams 9 are incident at positions 213. The positions of incidence 213 fall in fields 217 which have a regular spacing P2 with respect to each other. Example values for the spacing P2 are 10 micrometers, 100 micrometers, and 200 micrometers.

[0084] The primary particle beams 3 are generated in a beam generation device 300 comprising at least one particle source 301 (e.g., an electron source), at least one collimating lens 303, a multi-aperture arrangement 305, and a field lens 307. The particle source 301 generates a divergent particle beam 309 which is collimated or at least substantially collimated by the collimating lens 303 to form a beam 311 which illuminates the multi-aperture arrangement 305.

[0085] Figure 1 Excerpt I3 in Fig. 3 shows a plan view of the multi-aperture arrangement 305. The multi-aperture arrangement 305 comprises a multi-aperture plate 313 having a plurality of openings or holes 315 formed therein. The midpoints 317 of the openings 315 are arranged in a field 319 which is imaged into the field 103 in the object plane 101 formed by the beam spots 5. The spacing P3 between the midpoints 317 of the holes 315 can have example values of 5 micrometers, 100 micrometers, and 200 micrometers. The diameter D of the holes 315 is smaller than the spacing P3 between the hole midpoints. Example values for the diameter D are 0.2 x P3, 0.4 x P3, and 0.8 x P3.

[0086] The particles of the illuminating particle beam 311 pass through the holes 315 and form the particle beams 3. The particles of the illuminating beam 311 which impinge on the plate 313 are absorbed by the plate 313 and do not contribute to the formation of the particle beams 3.

[0087] Due to the applied electrostatic field, the multi-aperture arrangement 305 focuses each particle beam 3 such that a beam focus 323 is formed in a plane 325. Alternatively, the beam focus 323 can be virtual. The diameter of the beam focus 323 can be, for example, 10 nanometers, 100 nanometers, and 1 micrometer.

[0088] The field lens 307 and the objective lens 102 provide a first imaging particle optical unit for imaging the plane 325 in which the beam focus 323 is formed onto the first plane 101 such that the field 103 of the incident position 5 or beam spot appears there. If the surface of the object 7 is arranged in the first plane, the beam spot is formed accordingly on the object surface.

[0089] The objective lens 102 and the projection lens arrangement 205 provide a second imaging particle optical unit for imaging the first plane 101 onto the detection plane 211. Thus, the objective lens 102 is a lens which is part of both the first and the second particle optical unit, whereas the field lens 307 belongs only to the first particle optical unit and the projection lens 205 only to the second particle optical unit.

[0090] The beam switch 400 is arranged in the beam path of the first particle optical unit between the multi-aperture device 305 and the objective lens system 100. The beam switch 400 is also part of the second optical unit in the beam path between the objective lens system 100 and the detector system 200.

[0091] Further information on such multi-beam particle beam systems and components used therein, such as particle sources, multi-aperture plates and lenses, can be obtained from the international patent applications WO 2005 / 024881 A2, WO 2007 / 028595 A2, WO 2007 / 028596 A1, WO 201 1 / 124352 A1 and WO 2007 / 060017 A2 and the German patent applications DE 10 2013 016 1 13 A1 and DE 10 2013 014 976 A1, the entire contents of which are incorporated herein by reference.

[0092] The multi-beam particle beam system is further provided with a computer system 10 which is configured for controlling the individual particle optical components of the multi-beam particle beam system and for evaluating and analyzing the signals obtained by the multi-detector 209. In this case, the computer system 10 can be constituted by a plurality of individual computers or components.

[0093] Figure 2A particle beam system 1 is schematically shown, which comprises a multi-beamlet deflection device 350 and which comprises a beam stop 120 arranged in the region of the intersection plane 111 of the individual particle beams 3, 3a. The beam paths are presented in a very simplified manner. Charged particles emitted from a particle source (not shown) are incident on a multi-aperture arrangement or multi-beamlet generator 305, which is configured to generate a plurality of charged first individual particle beams 3 from the charged particle beam. In the exemplary embodiment shown, the multi-beamlet generator 305 has a focusing effect on the individual particle beams 3. This can be achieved, for example, by means of a combination of a multi-lens array and a multi-aperture plate, but other embodiment options for the multi-beamlet generator, such as a combination of a multi-detector array and a multi-aperture plate, are also possible. In this sense, the exemplary embodiment shown should not be interpreted as limiting.

[0094] Due to the focusing effect of the multi-beamlet generator 305 in the example shown, a beam focus 323 occurs in a focal plane downstream of the multi-beamlet generator 305 with respect to the particle-optical beam path. In the example shown, the multi-beamlet deflection device 350 is arranged flush with this focal plane or flush with the beam focus 323. In the example shown, this multi-beamlet deflection device 350 consists of two mutually parallel deflection plates (a pair). An electric field can be applied between these deflection plates. The multi-beamlet deflection device 350 is arranged in the first particle-optical beam path downstream of the multi-beamlet generator 305 and upstream of the field lens system 307. This arrangement prevents the multi-beamlet generator 305 from being unintentionally electrostatically charged, in particular in an inhomogeneous manner, by the incident particle beam during beam deflection by the multi-beamlet deflection device 350.

[0095] Now, in the drawings of Figure 2 two different first particle-optical beam paths of the individual particle beams 3 are depicted: the individual particle beams 3a, which pass through the particle beam system 1 without experiencing a deflection caused by the multi-beamlet deflection device 350, are indicated in the drawings in dashed lines and labeled with the reference symbol 3a. Conversely, if the multi-beamlet deflection device 350 is switched on or activated, the individual particle beams 3b will follow a different particle-optical beam path, which is schematically represented in Figure 2 by dotted lines.

[0096] If one now first considers the undisturbed particle-optical beam path of the undeflected individual particle beam 3a, the individual particle beam 3a, after passing through the field lens system 307, passes through the beam switch 400 and then through the particle-optical objective 102, which images the individual particle beam 3a on an object (not shown). The individual particle beams 3a cross one another between the field lens system 307 and the objective 102 or between the beam switch 400 and the objective 102 and form a so-called intersection point 110. This intersection point 110 lies in an intersection plane 111. Within the region of the intersection point 110 or within the intersection plane 111, the particle beam diameter of the entire beam array of the individual particle beams 3a is reduced or, in the best case, is at a minimum. If the position of the intersecting individual particle beams 110 is now moved within the intersection plane 111, a space-saving measure is provided at this moved position by a beam stop. In Figure 2 Such a beam stop 120 is shown in Fig. 1 1. If the multi-beam deflection device 350 is activated, or if an electric field is applied between the parallel plates, the individual particle beams 3b undergo a lateral deflection. After passing through the field lens system 307 or the beam switch 400, the individual particle beams 3b intersect within the intersection plane 111 at a position at a deflection distance d; here, d denotes the parallel offset of the intersection point 110 in the intersection plane 111. The upper edge of the beam stop 120 lies approximately flush with the intersection plane 111. Thus, the deflected individual particle beams 3b enter the beam stop 120 with a particle beam diameter of the individual particle beams which is as small as possible or is at a minimum. Since the overall particle beam diameter is small, it is also possible to realize the beam stop 120 in a cup-shaped manner. Here, cup-shaped means that the beam stop 120 has a certain depth and the incident individual particle beams 3b do not only hit a flat plate. Preferably, the depth of the cup is greater than the diameter of the cup 120. The deeper and narrower (aspect ratio) the cup 120 can be realized and the deeper the individual particle beams 3b deflected by the multi-beam deflection device 350 can penetrate into the cup, the better the effect of the beam stop 120. In the example shown, the cup 120 has a more rotationally symmetrical embodiment with respect to the optical axis Z of the particle beam system 1. This is advantageous because the deflection of the individual particle beams 3b can be realized in different directions. However, it is also possible to realize the cup 120 as non-rotationally symmetrical with respect to the optical axis Z, for example, to provide the cup only on one side of the optical axis Z.

[0097] Figure 2A second stage multi-beam deflection device 351 is shown which is provided selectively and which is arranged in the particle optical beam path between the multi-beam deflection device 350 and the field lens system 307 or the beam switch 400. By means of this selective second stage, it is possible to set the beam path of the deflected individual particle beams 3b more precisely when masking is carried out. Thus, for example, it is possible to set the angle of incidence of the individual particle beams 3b on the beam stop 120 in the cross-over plane 111 precisely. In addition or alternatively, a parallel offset of the individual particle beams 3b can be set in the upper focal plane of the objective 102, as has already been explained in detail previously, which allows very fast and precise masking, for example during line jumps or area changes.

[0098] Figure 3 A particle beam system 1 according to a second embodiment of the application is shown schematically which comprises a multi-beam deflection device 350 and comprises a beam stop 320. In principle, Figure 2 and 3 the same components are denoted by the same reference symbols in the respectively shown particle beam systems 1. In order to avoid unnecessary repetitions, the explanations below concentrate mainly on the relevant differences between the embodiment variants shown in Figure 3 and the embodiment variants already described in Figure 2 The beam paths are likewise presented in a very simplified manner.

[0099] In the particle beam system 1 shown in Figure 3 the beam stop 320 is located at a different position, precisely between the multi-beam deflection device 350 and the field lens system 307 or the beam switch 400. In the example shown, the beam stop 320 is located in the intermediate image plane, i.e. the plane in which the individual particle beams are focused. Thus, for the first particle optical beam path, the beam stop 320 in this solution is located further up in the particle optical beam path, i.e. closer to the source side, compared to the embodiment in Figure 2 However, this also applies to the region of the intermediate image in which the particle beam diameter is reduced or at best minimal. However, in this case this relates to the respective particle beam diameter of the individual particle beams 3. The beam stop 320 can likewise be arranged in the region of the intermediate image in a relatively space-saving manner.

[0100] In the exemplary embodiment shown in Figure 3 the beam stop 320 comprises an aperture array. This is shown schematically by the dashed lines of the beam stop 320 at the intermediate image. When the multi-beam deflection device 350 is deactivated, the individual particle beams 3a pass through the beam stop 320 unhindered. However, when the multi-beam deflection device 350 is activated, the particle beams 3b are deflected in the intermediate image plane and impinge on the plate of the aperture array 320. Thus, the individual particle beams 3b are masked and no longer reach the object (not shown).

[0101] Furthermore, since the individual particle beams 3a are very clearly separated from each other in the intermediate image region, they can also be easily separated and moved laterally within the intermediate image plane by means of the multi-beam deflection device 350. In this case, very precise work is required to even help precisely block the individual particle beams 3. Here, when the multi-beam deflection device 350 is activated, the central beam of each individual particle beam 3a, 3b preferably passes orthogonally through the aperture of the beam terminator 320, or orthogonally strikes the plate of the aperture array 320.

[0102] and Figure 2 Compared to the illustrated embodiment, the drift path between the position of the multi-beam deflection device 350 and the beam terminator 320 is reduced here; however, since a small offset of the individual particle beam 3 within the intermediate image plane is sufficient to mask or obscure the individual particle beam 3, operation on the multi-beam deflection device 350 only requires a relatively low voltage. For example, with a drift path of approximately 5 cm, the offset here is approximately 50 μm, which corresponds to an individual particle beam 3b being deflected by approximately 1 mrad. Figure 2 In the illustrated embodiment variant, with a drift path of approximately 30 cm, the offset of the intersection point 110 in the intersection plane 111 is approximately 1.5 mm, which corresponds to the individual particle beam 3b being deflected by approximately 5 mrad.

[0103] Figure 4 The arrangement of the cup-shaped beam terminator 120 within the objective lens 102 is schematically shown. The particle optics objective lens 102 includes an upper pole piece 102a and a lower pole piece 102b. A magnetic field is generated between the pole pieces 102a and 102b, which focuses (not shown) the individual particle beams 3a passing through the objective lens 102. A beam tube 140 extends into the upper pole piece 102a of the objective lens 102. For example, in the upward direction, this beam tube 140 may be incorporated into a beam switch (not shown). A vacuum or high vacuum is generally present within the beam tube 140. Figure 4 In the example shown, the beam tube 140 has an embodiment that is rotationally symmetric about the optical axis Z of the system. Now, in the exemplary embodiment shown, the beam terminator 120 is located in the region of the upper pole shoe 102a and in the region of the intersection of the individual particle beams 3 within the beam tube 140, wherein the beam terminator 120 has a cup shape.

[0104] The cup-shaped beam terminator 120 includes a channel opening 134 and a groove 130. In the non-deflection state, individual particle beams 3a pass through the beam terminator 120 via the channel opening 134. However, if the multi-beam deflection device 350 ( Figure 4 When (not shown in the image) is activated, the individual particle beams undergo deflection, which is caused by... Figure 4The individual particle beams 3b are represented by reference signs 3b in the drawing. The individual particle beams 3b hit a groove 130 of the beam stop 120, which has a ring-shaped cross section. The groove 130 is relatively deep compared to its width.

[0105] Furthermore, Figure 4 It is shown that it is possible to mount the cup-shaped beam stop 120 in the upper pole piece 102a of the objective 102, in particular to screw it into it, via the lower pole piece 102b of the objective 102. The outer diameter D1 of the cup 120 is less than or equal to the aperture D2 of the lower pole piece 102b of the objective 102. This makes it possible to quickly exchange the beam stop 120 within the objective 102. The exchange is possible within about one hour. For this, it is only necessary to ventilate the sample chamber below the objective 102 (sample chamber not shown); it is not necessary to break the high vacuum in the upper region of the beam tube 140.

[0106] Figure 5 The structure of the cup-shaped beam stop 120 is shown schematically in cross section and in a 3D view. Its geometric design has various features that promote efficient beam capture. Overall, the cup-shaped beam stop 120 has an essentially rotationally symmetrical embodiment. This applies in particular to the upper region of the cup 120, the so-called beam insertion region 133.

[0107] In the example shown, the beam stop 20 contains a passage opening 134 and a groove 130 having a ring-shaped cross section. Now, in the beam entry region 133, a sharp edge 136 is provided at the top of the passage opening 134. This sharp edge 136 or an edge that tapers to a point ensures that only a few charge carriers have room at this point, so that it is even possible to charge this edge 136 with a small amount by means of an individual particle beam 3b hitting the edge 136. Furthermore, a conical surface 138 is provided, which is inclined with respect to the longitudinal axis of the cup and is remote from the longitudinal axis, which extends from this sharp edge 136 into the groove 130. This angled or conical surface 138 serves to reflect incident individual particle beams on the edge of the cup 120 and into the groove 130, for example even during masking. Furthermore, the diameter of the passage opening 134 widens in the beam entry region 133, starting from the beam entry opening of the passage opening 134, as seen from the beam direction. A undercut 137 is therefore provided in the beam entry region 133 in the region of the passage opening 134, so that the individual particle beams 3a entering the passage opening 134 do not come into contact with the inner tube 132 of the cup 120; rather, the distance between the individual particle beams 3a and the inner tube 132 of the cup remains sufficiently large.

[0108] An absorber material 135 is optionally provided in the lower region of the groove 130. Here, the absorber material 135 can be a material having a low backscatter coefficient for particle radiation, for example a material having a low atomic number, for example carbon, aluminum or beryllium or the like.

[0109] Furthermore, in the lower region of the cup 120 a thread 139 is provided, which is used to screw the cup 120 into the objective 102, in particular into the upper pole piece 102a of the objective 102. In particular, a hexagonal wrench 141 can be used for screwing in the screw.

[0110] Overall, the beam stopper 120 has a substantially rotationally symmetric configuration. In particular, the beam entry region 133, which forms the upper region of the cup or beam stopper 120, is rotationally symmetric. This facilitates an optimal or uniform charge distribution. Furthermore, this offers advantages in view of the Larmor rotation. For example, when changing the working point of the system (landing energy, beam current, etc.), the beamlet will rotate around the optical axis due to a change in the magnetic lens settings in the system. For the shielding process, this means that the direction in which the beamlets are deflected in the cross plane depends on the lens settings in the system. In principle, this rotation can be compensated by a corresponding change in the settings of the multi-beam deflection device. However, this compensation is not necessary in the case of a rotationally symmetric configuration of the beam stopper and a multi-beam deflection device and its control can have a simpler configuration.

[0111] Figure 6 The structure of another cup-shaped beam stopper 120 is shown schematically in cross section. This cup 120 also has a substantially rotationally symmetric configuration with respect to the optical axis Z of the particle beam system 1. As in the case of the cup 120 in Figure 5 Compared to the shown embodiment variant, Figure 6 The cup 120 in has a different configuration of the outer wall 131. It does not taper to a point in the upper region, but has a step and is slightly curved. This makes it easier to install / introduce the cup 120 into the pole piece of the objective. Furthermore, Figure 6 and Figure 5 Some dimensions of the cup 120 in differ from one another. In Figure 6 Some dimensions are specified in an exemplary manner in ; however, these should not be interpreted as a restriction of the invention. Thus, the depth of the groove 130 is 11 mm. In this case, the diameter of the passage opening 134 is 1.5 mm at the narrowest location at the upper edge 136. The width of the annular groove 130 is 0.5 mm.

[0112] Figure 7 The effect of three different settings of the multi-beam deflection device 350 is shown when the particle beam 3b is incident on the beam stopper 120. Figure 7a) shows two settings El and E2 in which the multi-beam deflection device 350 is activated and the beam 3b is deflected into the slot 130 of the beam stop 120. In contrast, in the setting E0 of the multi-beam deflection device 350, there is no deflection of the individual particle beams; rather, the plurality of individual particle beams 3a passes through the passage opening 134 of the beam stop 120 in a substantially unhindered manner. According to Figure 7 a), the individual particle beams 3b are deflected to the left in the setting El and to the right in the setting E2. This actuation according to the settings E0, El and E2 is advantageous, in particular in connection with the skip rows of the individual particle beams 3. For example, it is possible to operate the above-described particle beam system 1 in such a way that an object is scanned row by row by means of the first individual particle beam 3a. Between the scanning of the individual rows, there is a skip row, and in the course of the skip row from one row to the other, the individual particle beams 3b are masked by means of the multi-beam deflection device 350, so that the particle beams 3b impinge on the beam stop 120, 320. During each skip row, there is a corresponding deflection. Now, according to Figure 7 a), there is an alternation between the two settings El and E2 from skip row to skip row. Thus, at one point, the masking is to the left (El), while in the next case, it is to the right (E2). This leads to a symmetrical charging of the edges of the beam stop 120, which is swept through at the beginning and at the end of the masking of the particle beams. As a result, both the left and the right charge are compensated. Naturally, in addition to the settings El and E2, further settings E3 and E4, etc., can also be provided, and between these settings are alternated during the masking in order to better distribute the charge. The astigmatism generated by the charge can also be eliminated by means of a deflection in more than two directions, i.e., for example, by means of the settings El, E2, E3 and E4, which, for example, each correspond to a deflection direction that is arranged at 90° to one another. Furthermore, it is also possible to intentionally avoid masking directions that are found to be poorer, for example, due to local contamination.

[0113] Figure 7 b) and 7c) show a masking strategy that can be used in the case of relatively long masking, for example, between various image recordings and thus when changing the area of the recording. According to the preferred embodiment, the rotationally symmetrical slot 130 of the beam stop 120 is traversed in a dynamic manner. Thus, the deflected individual particle beams 3b move along a circular trajectory around the optical axis of the beam stop 120 or around the optical axis Z of the entire system. To this end, the multi-beam deflection device can comprise a plurality of pairs of electrodes arranged around the optical axis, which are influenced by a time-varying sinusoidal or cosine-type deflection potential. According to Figure 7c) a new arbitrary position will be reached during each masking procedure. The latter can be decided in a truly random or pseudo-statistical way. Thus, this is the case where the settings of the multi-beam deflection device 350 are decided and set in a random or pseudo-random way. The result of this random process is averaged and possible contaminations or charge accumulations are better distributed in this case.

[0114] Furthermore, it is also possible to switch back and forth between pre-defined positions, for example, according to Figure 7 a) the positions E1 and E2.

[0115] Figure 8 A possible adjustment of the multi-beam deflection device 350 is shown, which is set in combination with the cup-shaped beam stop 120. It is important that the beam stop 120 is hit correctly. For this, the deflection sensitivity of the beam mask 350 or the multi-beam deflection device 350 in the plane of the beam stop, for example, in the cross-plane 111, has to be known. However, due to space reasons, it is not possible to make a measurement there to check whether the beam stop 120 is hit correctly. Additional difficulties can arise if the multi-beam deflection device 350 can only deflect the individual particle beams 3 in one direction.

[0116] One approach to the solution is to use a further deflector 360. This further deflector 360 is located in the particle-optical beam path between the multi-beam deflection device 350 and the beam stop 120. If both the multi-beam deflection device 350 and the deflector 360 are deactivated, the multi-particle beam or the plurality of individual particle beams 3 extends along the optical axis Z of the system. Now, the multi-beam is deflected with the deflector 360 to the edge of the beam stop 120 (position A) so that the central beam 3c of the multi-beam array is exactly cut off at the beam stop 120 (dotted line). Then, the particle beams are deflected with the multi-beam deflection device 350 to the opposite edge of the beam stop 120 (position B) so that the central beam 3b of the multi-beam array is again cut off at the beam stop 120 (dashed line). The required multi-beam deflector voltage for this purpose is recorded and the sensitivity can be calculated with the aid of the known dimensions of the beam stop 120 (more precisely: the diameter of the inner opening of the beam stop 120) or the required multi-beam deflector voltage for deflecting the plurality of individual particle beams from the initial state into the groove 130 of the beam stop 120 can be calculated directly. Further adjustments can be made.

[0117] List of reference signs

[0118] 1 particle beam system

[0119] 3 primary particle beam

[0120] 3a particle beam not deflected by the multi-beam deflection device

[0121] 3b particle beam deflected by the multi-beam deflection device

[0122] 5 position

[0123] 7 object

[0124] 9 secondary particle beam

[0125] 10 computer system

[0126] 25 entry position

[0127] 100 objective system

[0128] 101 object plane

[0129] 102 objective

[0130] 102a upper pole piece of the objective

[0131] 102b lower pole piece of the objective

[0132] 103 field of entry positions in the object plane

[0133] 104 opening in the lower pole piece

[0134] 110 intersection point

[0135] 111 intersection plane

[0136] 120 beam stop, cup in the intersection plane

[0137] 130 groove

[0138] 131 outer wall of the groove / cup

[0139] 132 inner wall of the groove

[0140] 133 beam entry area, upper area of the cup

[0141] 134 passage opening

[0142] 135 absorber material, material with low backscattering coefficient

[0143] 136 sharp edge

[0144] 137 undercut

[0145] 138 inclined surface

[0146] 139 screw thread

[0147] 140 beam tube

[0148] 141 hexagonal wrench

[0149] 200 detector system

[0150] 205 projection lens

[0151] 209 particle multi-detector

[0152] 211 detection plane

[0153] 213 incident position for detection

[0154] 217 field of incident positions for detection

[0155] 300 beam generating device

[0156] 301 particle source

[0157] 303 collimator lens

[0158] 305 multi-aperture configuration

[0159] 307 field lens, field lens system

[0160] 309 diverging particle beam

[0161] 311 particle beam

[0162] 313 multi-aperture plate

[0163] 315 aperture

[0164] 319 field of apertures

[0165] 320 beam stop at intermediate image

[0166] 323 beam focal point

[0167] 325 focal plane

[0168] 350 multi-beam deflection device

[0169] 350 multi-beam deflection device

[0170] 351 (selective) 2nd stage of multi-beam deflection device

[0171] 360 deflector

[0172] 400 beam switch

[0173] A position, edge of cup

[0174] B position, edge of cup

[0175] E0 beam in set 0 case of multi-beam deflection device

[0176] E1 beam in set 1 case of multi-beam deflection device

[0177] E2 beam in the case of setting 2 of the multi-beam deflection device

[0178] d parallel offset of the cross-over in the cross-over plane

[0179] D1 outer diameter of the cup

[0180] D2 opening diameter of the lower pole piece of the objective

[0181] P1 spacing between (object) incidence positions

[0182] P2 spacing between (detection) incidence positions

[0183] P3 spacing between centers of the apertures

Claims

1. A particle beam system, comprising: at least one particle source configured to generate a charged particle beam; a first particle optical unit having a first particle optical beam path, the first particle optical unit being configured to generate a plurality of individual particle beams and to image the individual particle beams on an object plane; and a second particle optical unit configured to image a plurality of second individual particle beams, which are emitted from an incident point in the object plane onto a detector unit; wherein the particle beam system further comprises: a multi-beam generator configured to generate a plurality of charged first individual particle beams from the charged particle beam; an objective through which the individual particle beams pass and which is configured to direct the first individual particle beams at the object plane such that the first individual particle beams impinge on the object plane at a plurality of incident points; a beam switch arranged in a first particle optical beam path between the multi-beam generator and the objective and in a second particle optical beam path between the objective and the detector unit, the first particle optical beam path and the second particle optical beam path branching within the beam switch; a beam stop; and a multi-beam deflection device with a controller, wherein the multi-beam deflection device is arranged in the first particle optical beam path downstream of the multi-beam generator and upstream of the beam switch, wherein the controller is configured to temporarily collectively deflect the first individual particle beams by means of the multi-beam deflection device such that the first individual particle beams are incident on the beam stop instead of on the object plane, and wherein the beam stop is arranged in the first particle optical beam path flush with a location of a particle beam diameter reduction or minimum, wherein the beam stop comprises a cup, wherein the cup has a passage opening along its longitudinal axis, and wherein a groove with an annular cross section is arranged around the passage opening for beam capture; and wherein the cup is arranged such that an optical axis of the particle beam system extends through the passage opening of the cup along the longitudinal axis of the cup, wherein a beam entry opening of the annular groove has a sharp edge on an inner ring; and wherein a surface is provided which is inclined with respect to the longitudinal axis of the cup and away from the longitudinal axis, the surface extending from the sharp edge into the groove.

2. The particle beam system according to claim 1, wherein the particle beam system is a multi-beam particle microscope.

3. The particle beam system according to claim 1, wherein the first particle optical beam path has a crossing plane of the individual particle beams upstream of the objective; and wherein the beam stop is arranged in the first particle optical beam path flush with the crossing plane.

4. The particle beam system according to any of the preceding claims, wherein the beam stop is arranged in the first particle optical beam path flush with an upper focal plane of the objective facing the multi-beam generator.

5. The particle beam system according to any of claims 1 to 3, wherein the multi-beam deflection device is arranged and / or controlled such that deflected individual particle beams experience a parallel shift in the crossing plane and / or upper focal plane of the objective.

6. The particle beam system according to claim 1, wherein the cup is rotationally symmetric with respect to an optical axis of the particle beam system.

7. The particle beam system according to claim 1, wherein a diameter of the passage opening in a beam entry region increases from the beam entry opening of the passage opening.

8. The particle beam system according to claim 1 or 7, wherein an absorber material is arranged at the bottom of the annular groove.

9. The particle beam system according to claim 7, wherein the cup is at least partially embedded in the objective, and / or the cup is exchangeable by means of an exchange tool.

10. The particle beam system according to claim 9, wherein the cup is at least partially screwed into the objective.

11. The particle beam system according to any of claims 1 to 3, wherein a distance between the multi-beam deflection device and the beam terminator is at least 20 cm.

12. The particle beam system according to claim 11, wherein the distance is at least 30 cm.

13. The particle beam system according to any of claims 1 to 3, wherein the multi-beam deflection device comprises deflection plates.

14. The particle beam system according to any of claims 1 to 3, wherein the multi-beam deflection device has a multi-stage embodiment.

15. The particle beam system according to any of claims 1 to 3, wherein the multi-beam deflection device is configured such that the individual particle beams can be deflected in different deflection directions.

16. A method of operating a particle beam system according to any of the preceding claims 1 to 15, the method comprising the steps of: - scanning an object by scanning a plurality of individual particle beams in a first row; - scanning the object by scanning the plurality of individual particle beams in a second row; and - deflecting the individual particle beams by means of a multi-beam deflection device during a row jump from the first row to the second row in accordance with a first setting of the multi-beam deflection device.

17. The method according to claim 16, further comprising the steps of: - scanning the object by scanning the plurality of individual particle beams in a third row; and - deflecting the individual particle beams by means of the multi-beam deflection device during a row jump from the second row to the third row in accordance with a second setting of the multi-beam deflection device, wherein the second setting is different from the first setting.

18. The method according to claim 16, wherein different settings of the multi-beam deflection device are chosen randomly.

19. A method of operating a particle beam system according to any of claims 1 to 15, the method comprising the steps of: - scanning a first region of an object by scanning a plurality of individual particle beams over the first region; - scanning a second region of the object by scanning the plurality of individual particle beams over the second region; and - deflecting the individual particle beams by means of a multi-beam deflection device during a region change from the first region to the second region in accordance with at least a first setting of the multi-beam deflection device.

20. The method according to claim 19, wherein different settings of the multi-beam deflection device are used in an alternating manner during the region change.

21. The method according to claim 19, wherein different settings of the multi-beam deflection device are chosen and used randomly.

22. The method according to any of claims 16 to 21, - wherein a rotationally symmetric cup is used, the cup having a passage opening along its longitudinal axis, wherein a groove having an annular cross-section is arranged around the passage opening for beam capture; and - wherein the cup is exchangeable by means of an exchange tool. wherein the annular trench for beam capture is traversed by means of a setting of the multi-beam deflection device.

23. A computer program product comprising program code for carrying out the method of any one of claims 16 to 22.

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