Multi-beam charged particle imaging equipment

Abstract

Multi-beam charged particle imaging device. A charged particle imaging device, comprising: a sample holder for holding a sample; a particle light column for: generating a plurality of charged particle beams by directing an origin charged particle beam onto an aperture plate having a corresponding plurality of holes within a footprint of the origin beam; directing the beams toward the sample, wherein: the aperture plate comprises a plurality of different regions, the plurality of different regions comprising mutually different hole patterns arranged within the footprint of the origin beam; the particle light column comprises a selector device positioned downstream of the aperture plate, the selector device for selecting a beam array from a selected one of the regions for directing onto the sample.

Description

[0001] The present invention relates to a charged particle imaging device, comprising:

[0002] - a sample holder for holding the sample;

[0003] - Particle beams, which are used for:

[0004] generating a plurality of charged particle beams by directing an originating charged particle beam onto an aperture plate having a corresponding plurality of apertures within the footprint of the originating beam;

[0005] • Directing the beam towards the specimen.

[0006] The invention also relates to a method of using such an apparatus.

[0007] Examples of charged particle imaging equipment include charged particle microscopes (CPMs) and charged particle lithography imaging systems (used, among other things, to write integrated circuit patterns onto photoresist-coated semiconductor substrates). Charged particle microscopy, particularly in the form of electron microscopy, is a well-known and increasingly important technique for imaging microscopic objects. Historically, the basic genus of electron microscopes has evolved into a number of well-known equipment species, such as the transmission electron microscope (TEM), the scanning electron microscope (SEM) and the scanning transmission electron microscope (STEM), as well as various subspecies, such as the so-called "dual beam" equipment (e.g. FIB-SEM), which additionally employs a "processing" focused ion beam (FIB), allowing support activities such as, for example, ion beam milling or ion beam induced deposition (IBID). More specifically:

[0008] - In a SEM, the emission of "auxiliary" radiation from the sample is accelerated by irradiating the sample with a scanning electron beam, for example in the form of secondary electrons, backscattered electrons, X-rays and cathodoluminescence (infrared, visible and / or ultraviolet photons); one or more components of this emitted radiation are then detected and used for image accumulation purposes.

[0009] - In a TEM, the electron beam used to irradiate the sample is chosen to have a sufficiently high energy to penetrate the sample (which, for this purpose, will generally be thinner than in the case of an SEM sample); the transmitted electrons emitted from the sample can then be used to create an image. When such a TEM is operated in scanning mode (hence a STEM), the image is accumulated during the scanning movement of the irradiating electron beam.

[0010] -SEM can also be used in "transmission mode", for example when using relatively thin samples and relatively high incident beam energy. Such tools are often called "TSEM" (Transmission SEM), and they usually have a relatively basic imaging system (e.g., a single lens and deflector) placed between the sample and the post-sample detector.

[0011] As an alternative to using electrons as the irradiation beam, charged particle microscopy can also be performed using other kinds of charged particles. In this regard, the phrase "charged particles" should be interpreted broadly to cover, for example, electrons, positive ions (e.g., Ga or He ions), negative ions (e.g., oxygen), protons, and positrons. Regarding non-electron-based charged particle microscopy, some further information can be gleaned, for example, from references such as:

[0012] https: / / en.wikipedia.org / wiki / Focused_ion_beam

[0013] http: / / en.wikipedia.org / wiki / Scanning_Helium_Ion_Microscope

[0014] - W. H. Escovitz, T. R. Fox and R. Levi-Setti, "Scanning Transmission Ion Microscope with a Field Ion Source" Proc. Nat. Acad. Sci. USA 72 (5) Pages 1826-1828 (1975).

[0015] http: / / www.ncbi.nlm.nih.gov / pubmed / 22472444

[0016] It should be noted that besides imaging and performing (local) surface modifications (such as milling, etching, deposition, etc.), CPM can also have other functions, such as examining diffraction patterns, performing spectral analysis, studying ion channeling / ion backscattering (Rutherford backscattering spectroscopy), etc.

[0017] In a lithographic imaging system (e.g., a wafer stepper / wafer scanner), a beam of actinic radiation is used to pattern a layer of energy-sensitive material (photoresist) that has been provided (e.g., spun-on) on the surface of a substrate (e.g., a semiconductor wafer). Traditionally, the actinic beam has comprised a broad beam (e.g., from a mercury lamp or a laser) that is passed through a mask / reticle and later imparts its pattern to the photosensitizer. However, other types of lithographic imaging systems utilize charged particles, such as so-called "direct-write" electron beam tools, which track one or more electron beams over the photosensitive layer according to the desired pattern. Still other lithographic imaging system concepts utilize ion beams.

[0018] In all cases, the charged particle imaging equipment will include at least the following components:

[0019] - Charged particle sources, such as:

[0020] Field emission gun (FEG; Schottky or cold FEG) or LaB 6 heat sources, e.g., in the case of electronics;

[0021] • Liquid Metal Ion Source (LMIS), Nanopore Ion Source (NAIS) or RF generated ion plasma source, e.g. in the case of ions.

[0022] - A particle light column (illuminator) which is used to manipulate the "raw" particle beam from the source and to perform certain operations on it, such as focusing, aberration mitigation, cropping (using diaphragms), filtering, etc. It usually comprises one or more (charged particle) lenses and may also comprise other types of (particle) optical components. If necessary, the illuminator may be provided with a deflector system which can be called upon to make its outgoing beam perform a scanning motion across the sample being studied.

[0023] - a sample holder on which the sample under investigation can be fixed and placed (e.g. tilted, rotated). If necessary, this holder can be moved to affect the scanning movement of the sample relative to the beam. Generally, such a sample holder will be connected to a positioning system. When designed for holding cryogenic samples, the sample holder may include means for maintaining said sample at cryogenic temperature, for example using a suitably connected cryogen barrel.

[0024] Transmission-based CPMs, such as (S)TEM or TSEM, or mask-based lithography imaging systems will additionally include:

[0025] - An imaging system, which basically transports the charged particles through a sample (plane) [or mask plane, in lithography] and directs (focuses) them onto a target, such as a detection / imaging device, a spectroscopic apparatus, a resist-coated wafer, etc. As with the illuminator mentioned above, the imaging system may also perform other functions, such as aberration mitigation, cropping, filtering, etc., and it typically includes one or more charged particle lenses and / or other types of particle optical components.

[0026] Conventional charged particle imaging devices have utilized a single imaging beam. However, in recent years, multi-beam device designs have begun to emerge. For example, multi-beam electron microscopes are described in a PhD thesis by one of the inventors: "196 Beams in a Scanning Electron Microscope", Ali Mohammadi-Gheidari, Delft University of Technology, The Netherlands, November 2013:

[0027] https: / / repositorv.tudelft.nl / islandora / object / uuid:98869173-12db- 49cf-9466-0341cf6ad845? collection=research

[0028] Furthermore, multi-electron beam lithography imaging systems are developed and marketed, for example, by the company Mapper Lithography BV, Delft, The Netherlands. The basic idea behind the simultaneous use of several main beams - rather than just a single beam - is that it can significantly increase throughput, since the use of a beam array allows "parallel imaging". However, the simultaneous use of multiple imaging beams (beamlets; sub-beams; component beams) also presents various technical problems and challenges that need to be satisfactorily addressed. Examples of areas where such problems arise include multi-beam generation / adjustment and aberration control.

[0029] The object of the present invention is to provide an improved multi-beam charged particle imaging device. More specifically, it is an object of the present invention that such a device should allow a more flexible multi-beam generation / regulation than prior art microscopes. In particular, it is an object of the present invention to provide an innovative way of regulating the beam current / beam modality in such a device.

[0030] These and other objects are achieved by the device proposed in the above opening paragraph, characterized in that:

[0031] - the aperture plate comprises a plurality of different regions comprising mutually different aperture patterns arranged within the origin beam footprint;

[0032] - the particle optical column comprises selector means positioned downstream of the aperture plate for selecting an array of beams from selected ones of the areas to be directed onto the sample.

[0033] Conventional particle beam designs tend to include one or more beam crossovers, where the beam envelopes converge (focus) through a "waist" (minimum width) before diverging again. Such a crossover can be a convenient location to place an adjustable aperture in between or near it, whose width can be varied so as to reduce / re-expand the waist width and use it to reduce the total beam current. In principle, such a current regulation mechanism can be used for both single-beam and multi-beam particle optical designs. However, for multi-beam designs, where the cumulative beam current is often much higher than for single-beam designs, such a crossover (and in particular the beam paths that converge to / diverge) represents a location where the interaction between the charged particles in the various beams may become unacceptable Coulomb degrees, with noticeable blurring and loss of image brightness as concomitant effects. For this reason, if possible, it may be necessary to avoid beam crossovers in multi-beam designs. However, when crossovers are avoided, the convenient beam current regulation mechanism mentioned above becomes non-existent.

[0034] The device design of the present invention provides a solution to this problem, among other problems and functions. More specifically, in one embodiment of the present invention, at least two of the zones in the orifice plate have substantially the same distribution of holes, but differ in the diameter of the holes in said distribution. In other words: if the center point in each hole defines a reference "node", then (at least) two zones Z A and Z B The nodes in the same distribution (array / matrix arrangement) but the size of the hole centered on each node is different in Z A With Z B Having different aperture sizes in this way - for the same / common aperture distribution - allows adjusting the beam current values ​​of all component beams in a multi-beam array. For example, Z A and Z B Each of may comprise a regular array of orthogonal or hexagonal holes, but with respective hole widths of, for example, 5 μm and 20 μm.

[0035] In another embodiment of the invention, one of the regions includes a single through hole for allowing a portion of the origin (precursor; initial) beam to pass through without subdividing the portion (with reference to the terminology used above, it will be understood that an "array" of beams emanating from a region having a single through hole will herein include only one component beam). The presence of such a through hole advantageously allows the device to be used in a single beam mode rather than a multi-beam mode when required. This may be useful, for example, if a multi-beam implementation of a single beam architecture suffers from certain suboptimal aspects, in which case it may be desirable to be able to revert to single beam mode when required. For example, a multi-beam SEM is not prone to sample tilting, and it may also require a more complex detector architecture (e.g. for differential backscattered electron detection) than a single beam ("conventional") SEM; in this regard, one can easily grasp the appeal of being able to easily revert to single beam mode when necessary / desired, as such functionality / multi-modality provides the advantages of "the best of both worlds" and increases the number of applications in which the device of the invention can be used. If desired, the aperture plate may comprise a plurality of different zones with different such "single beam" through-holes of various diameters - in order to achieve single beams with different beam currents. Alternatively, only a single zone with (relatively large) through-holes may be used, and an adjustable opening used downstream of the aperture plate (e.g. in a selector device) to reduce / reduce the beam diameter when a lower single beam current is desired (e.g. see Figure 3 ). In yet another possible case, an adjustable lens assembly positioned between the aperture plate and the selector device can be used to control the size of the single beam spot that ultimately impacts the sample. Of course, various combinations / hybrids of these various methods are also possible. The multiple selectable areas {Zi}Also allows other effects / advantages to be achieved. For example:

[0036] - Two different zones Z 1 , Z 2 may have the same pore size and basic pore distribution geometry (e.g., orthogonal), but may differ in the number / spacing of their pores - e.g., Z 1 can have an nxn array of holes, and Z 2 Can have mxm array, n≠m.

[0037] - Two different zones Z H , Z K Different basic pore distribution geometries are possible - for example, Z H can have an orthogonal pore distribution, while Z K It may have a hexagonal ("honeycomb") pore distribution.

[0038] This may be desirable, for example, in lithography imaging applications, where it may be desirable to be able to tailor the beam configuration (aperture distribution geometry) to the specific integrated circuit layout being imaged, e.g., in terms of non-isotropy of dense / non-dense lines, line orientation, etc. Furthermore, it allows the beam configuration to be matched to, for example, the crystal orientation / size of a specific sample.

[0039] With respect to the selector device of the present invention, this is advantageously located downstream (i.e., behind) the orifice plate. This means that the selector device can be located near a charged particle source - an environment that is typically characterized by very high (ultra-high) vacuum and high voltage levels. These aspects make it difficult / impractical to locate / operate non-essential subsystems near the source. For example, very high vacuum levels in the vicinity of the source (e.g., typically ~10 -9 mbar, and ~10 for CFEG -10 -10 -11 mbar) imposes significant restrictions on material compatibility (regarding degassing / bake-out durability) and vacuum feedthroughs, and limits choices, e.g., regarding motor / actuator type and wiring. At the same time, the high voltage levels in the vicinity of the source (e.g., up to ~300 kV in the case of STEM) restrict the type / location of structures used, such as metal electrodes and / or actuating rods, for example (which may result in arcing if not properly designed / implemented). Such considerations would make it difficult to construct a feasible, satisfactorily operating selector device upstream of the orifice plate. However, downstream of the orifice plate, conditions are more favorable because:

[0040] - There are no high voltage sources in this area;

[0041] -The vacuum degree here is usually not high, and the typical value near the sample is ~10 -7mbar, and the vacuum in the beam tube is as low as 10 -5 At these values, outgassing is usually not a significant problem, baking is usually not required, and there are therefore more options in terms of materials / construction.

[0042] Therefore, it is easier to achieve a satisfactorily performing electrical / magnetic / mechanical system in this area, as will now be described in more detail.

[0043] Since the originating beam in the apparatus of the invention passes through multiple areas of the aperture plate at once, the main task of the selector device is to select specific areas of the sample that are allowed to be irradiated, while preventing other areas from doing so; in this case, the selector device therefore acts as an area selection mechanism. In other words, if the beam collection / envelope emerging from the aperture plate is considered to have a reference cross-section, then the selector device is used to limit only specific (selectable) parts of this cross-section to further enter the sample. In one embodiment of the present invention, the selector device comprises a masking plate with restricting openings, which can be positioned so as to pass only selected beam arrays (beam segments) from selected areas to the sample. Conveniently, if necessary, such a masking plate can be connected to a motor (or other actuator) to controllably position the masking plate / restricting opening relative to the reference cross-section of the beam / particle optical axis of the column. The shape / size of the restricting opening can match / complement the shape / size of the respective area in the aperture plate (taking into account the column magnification). Furthermore, if necessary, there can be multiple restricting openings, with the specific opening being selected as needed / desired. See. Figure 3 , for example. The masking plate described here is conveniently positioned at a plane in which (the beams from) the individual areas of the aperture plate are relatively well separated from one another - this simplifies, among other things, the dimensioning / manufacturing of such a masking plate.

[0044] In a refinement of the embodiment in the preceding paragraph, the selector device additionally comprises a deflector assembly positioned before the aforementioned masking plate (at an arbitrary position) for deflecting the beam envelope relative to the masking plate so as to direct only the selected beam array from the selected area through the restricting opening. Such a deflector assembly may, for example, comprise one or more sets of electrostatic and / or magnetic deflectors to controllably position the beam cross section relative to the masking plate / restricting opening. In a refinement of this basic method, the deflectors are paired so that a given deflection introduced before the masking plate (by a first deflector set) is compensated / cancelled after the masking plate (by a second deflector set), thereby ensuring that there is no residual (angular) deflection when the beam strikes the sample.

[0045] The present invention is advantageously applied in scanning systems which include a scanning assembly for producing a relative scanning motion of a sample and a beam array. Depending on the choice, such scanning may require moving the beam array relative to the sample, or moving the sample relative to the beam array, or a combination of both. For example, in a conventional SEM / STEM, the scanning motion is usually achieved only by beam deflection and not by sample displacement. On the other hand, in conventional photolithographic imaging systems, it is more common to use a scanning stage to move the sample. If beam scanning is used, the scanning deflector employed can be conveniently positioned downstream of the selector device of the present invention (see, for example, Figure 1 ). Depending on the exact setup used, there are certain reasons why it may be more advantageous to choose a (mainly) sample scan rather than a (mainly) beam scan, for example as described in the aforementioned co-pending application EP18176596.7.

[0046] With regard to the number of input beams in the beam array used in the present invention, it should be emphasized that this is a free choice. On the one hand, the greater the number of beams, the greater the throughput enhancement that can be achieved; on the other hand, a greater number of beams will increase the complexity of the overall system. The skilled person will be able to find a compromise between these competing effects and choose a number that is appropriate for a given scenario / use case. For example, a satisfactory system can be built using 196 beams in a 14×14 array - although many other beam numbers / configurations are possible.

[0047] The present invention will now be described in detail based on exemplary embodiments and the accompanying schematic diagrams, in which:

[0048] Figure 1 Shown is a longitudinal cross-sectional elevation view of an embodiment of a charged particle imaging apparatus - in this case, an electron microscope - in which the present invention is implemented.

[0049] Figure 2 It shows how an array of electron beams can be generated from a single originating beam.

[0050] Figure 3 There are shown elevation views and plan views of various components arranged along the particle-optical axis in an embodiment of a charged particle device according to the invention.

[0051] Figure 4A and 4B Alternative embodiments of possible aperture plates that may be used with embodiments of the present invention are shown.

[0052] In the various figures, corresponding parts are indicated by corresponding reference characters where relevant.

[0053] Example 1

[0054] Figure 1(not to scale) is a highly schematic diagram of an embodiment of a charged particle imaging apparatus in which the present invention is utilized; more specifically, it shows an embodiment of a SEM - however, in the context of the present invention it may also be, for example, a STEM or a lithography imaging system. The microscope M comprises a particle light column / illuminator 1 which generates an electron beam (charged particle beam) propagating along a particle-optical axis B′. The particle light column 1 is mounted on a vacuum chamber 3 which comprises a sample holder 17 and an associated stage / actuator 19 for holding / positioning a sample S. The vacuum chamber 3 is evacuated using a vacuum pump (not shown). With the aid of a voltage source 21, the sample holder 17 or at least the sample S can be biased (floated) to a potential relative to ground if desired.

[0055] The particle beam 1 comprises an electron source (charged particle source) 5 (such as, for example, a Schottky emitter, a cold FEG or a LaB 6 filament), lenses 11, 13 for focusing the electron beam onto the sample S, and a deflection unit 15 for performing beam deflection / scanning of the beam. By scanning the electron beam over the sample S, output radiation - comprising, for example, a flux of X-rays, infrared / visible / ultraviolet light, secondary electrons and / or backscattered electrons - is emitted from the sample S. The detectors 23, 27 can be selected from a variety of possible detector types, which can be used to examine different types / morphologies of this output radiation. In the device depicted here, the following detector selections have been made:

[0056] The detector 23 is a segmented electron detector comprising a plurality of independent detection segments (eg quadrants) arranged around a central aperture 25 (encompassing the optical axis B′). Such a detector can be used, for example, to study the angular dependence of the electron flux emerging from the sample S.

[0057] The detector 27 is, for example, an X-ray detector which can be used to record X-rays emitted from the sample S and thereby perform energy dispersive X-ray spectroscopy (EDX). Alternatively, it can be, for example, a cathodoluminescence detector.

[0058] Alternatively / complementarily, a backscattered electron detector such as that described in the aforementioned co-pending patent application EP18176596.7 may be used. Since the detected output radiation is position dependent (due to the scanning motion), the information obtained from the detectors 23, 27 will also be position dependent and can therefore be used to assemble an image of the detector output map substantially as a function of the scanning path position on the sample S. The signals from the detectors 23, 27 are transmitted along a control line (bus) 29", processed by a controller 29, and displayed on a display unit 31. Such processing may include operations such as combination, integration, subtraction, pseudo-coloring, edge enhancement and other processing known to those skilled in the art. In addition, automatic recognition processes (e.g. for particle analysis) may be included in such processing.

[0059] Those skilled in the art will appreciate various modifications and alternatives to this "basic" setup, including but not limited to:

[0060] - using dual primary beam materials - e.g. an electron beam for imaging and an ion beam for processing (or in some cases, imaging) the sample S;

[0061] - Using a controlled environment at the sample S - for example maintaining a pressure of a few mbar (as used in so called ambient SEM) or by admitting gases, like etching or precursor gases.

[0062] Essential to the invention is the fact that the single primary electron beam used in a conventional SEM is replaced here by a multi-beam array. Figure 2 Shows how to use Figure 1 Relatively minor modifications in the RF power generation process generate this multi-beam array. o Leaving the electron source 5, it passes through a series of (extraction / acceleration) electrodes 7 and impinges on an aperture plate 9 containing a plurality of apertures 9"; this structure 9 may also be referred to as an aperture lens array (ALA) - since the apertures 9" have a lens effect - and may be manufactured, for example, by etching an array of small apertures in a silicon wafer using thin film (MEMS) technology (see the above-mentioned PhD thesis). As a result of impinging on the ALA 9, the originating beam B o is transformed into a plurality of B sub-beams / sub-beams / component beams B″ having the same geometrical configuration as the plurality of apertures 9″ used to generate them. This beam array B then follows its course along the axis B′ through the illuminator 1 which directs it onto the sample S (see Figure 1 ).

[0063] In the present invention, ALA 9 takes a special form because it includes a number of different regions {Z i} - having hole patterns different from each other - arranged in the origin beam B obeam B occupies a space (on ALA 9) (so that multiple areas are o Simultaneous lighting / traversal). Figure 3 An example of this is shown in , where:

[0064] - The left side of the figure shows a front view of some components arranged along the electron path (see also Figure 1 and 2 );

[0065] - The right side of the figure shows a different plan view - not to the same scale - of two specific components, namely the ALA 9 and (parts of) the selector device 33 .

[0066] Starting with ALA 9 of the present invention, it can be seen in the current example that this includes five different regions, namely:

[0067] - Four substantially square quadrants Z 1 , Z 2 , Z 3 , Z 4 These all have 14×14 orthogonal configuration of beam holes, but they differ from each other in the diameter / width of these holes. More specifically, zone Z 1 has the largest hole, and the area Z 4 With the smallest hole, area Z 2 and Z 3 The progression between these two extreme cases is shown. For clarity, the perimeter of zone Z1 is marked with a dotted outline; the other quadrant zones Z 2 , Z 3 , Z 4 Similarly defined, but their perimeters are not dashed lines to avoid cluttering the figure. In the arrangement shown here, the beam apertures are circular, but this need not necessarily be the case and other shapes, such as ellipses, are possible.

[0068] -Central Area Z 5 (Location in area Z 1 -Z 4 The intersection / common corner of the Z region is the intersection of the Z region and the Z region, which here takes the form of a (relatively large) circular through hole. 5 This allows the depicted device to be used in a single beam mode, as will be explained in more detail below.

[0069] Turning now to the selector device 33 of the present invention, it can be seen that it is positioned downstream of the ALA 9 (see also Figure 1), and in the present example comprises two subcomponents, namely a masking plate 331 and a beam deflector assembly 332. In this particular case, the masking plate 331 comprises a movable strip 331′, which can be positioned / moved within the beam path by an actuator 331″, such as a motor. The strip 331′ shown (which can, for example, consist of a thin sheet of (MEMS-processed) silicon) has (in this particular case) seven different regions 35a, 35b, ..., 35g, each of which has a corresponding restrictive opening 37a, 37b, ... 37g. These openings (windows) 37a-37g have the following form:

[0070] - In the case of four zones 35a, 35b, 35c, 35d, the corresponding openings 37a, 37b, 37c, 37d take the form of open quadrants, although the relative positions of these open quadrants 37a-37d differ between zones 35a-35d. Zones 35a-35d are aligned with zone Z of the ALA 9. 1 -Z 4 By comparison, it can be seen that the openings 37a (upper right), 37b (upper left), 37c (lower left), and 37d (lower right) correspond to the positions of the regions Z. 1 , Z 2 , Z 3 and Z 4 The size of the openings 37a-37d corresponds to the area Z at the plane where the selector device 33 is located. 1 -Z 4 to match the size.

[0071] - In the case of three zones 35e, 35f, 35g, the corresponding openings 37e, 37f, 37g are in the form of central circular holes, although the size of these circular holes 37e-37g varies between zones 35e-35g. Comparing zones 35e-35g with ALA 9, it can be seen that all openings 37e-37g correspond in position to zone Z 5 The size of the openings 37e-37g is tailored to the area Z at the plane where the selector device 33 is located. 5 The size of

[0072] The maximum opening 37e is at the Z of this plane 5 The size corresponds exactly, or slightly larger.

[0073] The openings 37f and 37g are gradually smaller than the opening 37e.

[0074] Regarding the operation of the beam selector 33 in accordance with the ALA 9, this mainly involves two aspects, namely:

[0075] - moving the masking plate 331 so as to place a selected one of the restricting openings 37a-37g near / on the particle optical axis B′;

[0076] - Invoke the beam deflector assembly 332 - which may for example comprise a set of electrostatic deflection electrodes - to position (the beam array / beam cross-sectional portion emerging therefrom) the zone Z over the restrictive opening in question 1 -Z 5 A selected area in .

[0077] Clearly, using the masking plate 331 and deflector assembly 332 in this manner (eg, according to a position entry in a lookup table) will result in the 1 -Z 5 The beam array of the selected area in enters (and moves forward towards the sample S). More specifically:

[0078] - In area Z 1 -Z 4 In this case, since each of these regions contains apertures of different widths, they will produce different beam current values ​​for the various beams that make up the associated orthogonal 14×14 multi-beam array.

[0079] - In area Z 5 In this case, the beam current of this single beam mode can be reduced by selecting opening 37f or 37g instead of opening 37e.

[0080] Those skilled in the art will appreciate that the specific one-to-one correspondence described above need not be strictly adhered to; for example, a magnetic lens (assembly) positioned upstream of the masking plate 331 can be used to rotate the beam array impinging thereon, thereby potentially allowing (depending on the degree of rotation selected) a variety of different (quadrant-shaped) areas to be directed one at a time through a given restrictive opening.

[0081] The specific dimensions of components 9 and 331 and the apertures therein will depend on various factors, such as the specific charged particle column design, the desired beam current value, etc., and the skilled person will be well able to select values ​​that suit the needs of a given case. However, by way of providing some general guidance, the following non-binding examples may be considered:

[0082] -Zone Z 1 -Z 4 Typical diameter of individual pores in the microstructure: ca. 1-50 μm.

[0083] -Zone Z 5 Typical diameter of the through-holes: ca. 50-300 μm.

[0084] - Typical diameter of restrictive openings 37a-37d: ca. 0.1-1.5 mm.

[0085] - Typical diameter of restrictive openings 37e-37g: ca. 4-200 μm.

[0086] - Typical ALA9 region struck by the origin beam Bo: up to ca. 1.5×1.5 mm 2 .

[0087] With regard to the ALA 9 and the selector device 33 , it should be explicitly pointed out that the examples shown and described here are non-binding and that many alternatives are possible, for example with regard to the number and relative positioning / arrangement of the areas {Zi} in the ALA 9 , the way in which such areas differ from one another, the number / shape of the openings in the strip 331 ′, etc. In this regard, see, for example, the next embodiment.

[0088] Example 2.

[0089] Figure 4A and 4B Alternative embodiments of possible orifice plates that may be used with embodiments of the present invention are shown. More specifically:

[0090] - Figure 4A Shows something like Figure 3 The aperture plate / ALA of the ALA 9 in which it contains four quadrant areas with an orthogonal multi-beam configuration, nested around a single-beam through-hole. However, the mutual separation between the quadrant areas is larger here, allowing for a larger through-hole in the middle. This arrangement is Figure 3 A "roomier" alternative to ALA9.

[0091] - Figure 4B A situation is shown where the single beam aperture has been moved from the central position and positioned in its own quadrant. This arrangement allows the accompanying masking plate to be simplified if necessary, since all areas of the ALA can now be "serviced" through a (removable) square or circular restrictive opening.

Claims

1. A charged particle imaging device, comprising: A sample holder, used to hold the sample; Particle beams, which are used to: generating a plurality of charged particle beams by directing an originating charged particle beam onto an aperture plate having a corresponding plurality of apertures within a footprint of the originating beam; directing the beam toward the sample, Features: The aperture plate includes a plurality of different regions including mutually different aperture patterns arranged within the origin beam footprint; The particle optical column comprises a selector device positioned downstream of the aperture plate for selecting an array of beams from selected ones of the regions to be directed onto the sample.

2. The apparatus of claim 1, wherein at least two of the regions have substantially the same pore distribution but differ in the diameter of the pores in the distribution.

3. Apparatus according to claim 1 or 2, wherein one of the regions comprises a single through hole for allowing a portion of the originating beam to pass therethrough without subdividing the portion.

4. The apparatus of claim 3, wherein at least one of the following is used to reduce a beam current value of the beam passing through the single through hole in the aperture plate: a variable opening in said selector device; An adjustable lens assembly is disposed between the aperture plate and the selector device.

5. Apparatus according to claim 1 or 2, wherein the selector means comprises a masking plate having a restrictive opening which can be positioned to pass only the selected array of beams from the selected area to the sample.

6. An apparatus according to claim 5, wherein the selector device further includes a deflector assembly, which is positioned in front of the masking plate, and the deflector assembly is used to deflect the multiple beams relative to the masking plate so as to guide only the selected beam array from the selected area through the restrictive opening.

7. Apparatus according to claim 1 or 2, comprising a scanning assembly for producing a relative scanning motion of the sample and beam array.

8. The apparatus of claim 1 or 2, selected from the group consisting of: a charged particle microscope and a charged particle lithography imaging system.

9. A method of using a charged particle imaging device, the charged particle imaging device comprising: A sample holder, used to hold the sample; Particle beams, which are used to: generating a plurality of charged particle beams by directing an originating charged particle beam onto an aperture plate having a corresponding plurality of apertures within a footprint of the originating beam; directing the beam toward the sample, Features: configuring the aperture plate to include a plurality of distinct regions including mutually distinct aperture patterns arranged within the origin beam footprint; An array of beams is selected from selected ones of the regions for directing onto the sample using a selector device positioned downstream of the aperture plate.

10. The method according to claim 9, wherein: In a first use period, a first area of ​​the areas is selected to illuminate the sample with an array of beams, each beam in the array of beams having a first beam current value; In a second use period, a second area of ​​the areas is selected to illuminate the sample with an array of beams, each beam in the array of beams having a second different beam current value, Wherein the first region and the second region have substantially the same pore distribution but differ in the diameter of the pores in the distribution.

11. The method according to claim 9, wherein: The aperture plate is configured to include a region having a single through hole for allowing a portion of the origin beam to pass therethrough without subdividing the portion; The originating beam is directed onto the through-hole to produce a single beam mode of operation of the device.

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