Method for inspecting a sample and charged particle beam device

Abstract

A charged particle beam device for irradiating or inspecting a sample is described. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primaries. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The charged particle beam device further comprises a stage for supporting the sample.

Description

TECHNICAL FIELD

[0001] Embodiments relate to charged particle beam devices, e.g. for inspection system applications, test system applications, defect review or critical dimension applications, etc. Embodiments also relate to methods of operation of charged particle beam devices. More specifically, embodiments relate to charged particle beam devices as multi-beam systems for general purpose, such as imaging biological structures, and / or for high throughput EBI (electron beam inspection). Embodiments relate to apparatuses and methods of inspecting a surface of a sample using a multi-beam charged particle column. BACKGROUND

[0002] Modern semiconductor technology relies heavily on the precise control of various processes used during the production of integrated circuits. Therefore, wafers are repeatedly inspected in order to identify problems as early as possible. Furthermore, in order to ensure that masks can define the respective pattern precisely, masks or reticles are also inspected before actual use during wafer processing. The inspection of a wafer or mask for defects includes the inspection of the entire wafer or mask area (e.g. for 300 mm wafer production). In particular, the inspection of a wafer during wafer manufacturing includes the inspection of the entire wafer area in a short time which does not limit the production throughput of the inspection process.

[0003] Scanning electron microscopes (SEM) have been used for inspecting wafers. A single finely focused electron beam is used to scan the surface of the wafer. When the electron beam hits the wafer, secondary electrons and / or backscattered electrons (i.e. signal electrons) are generated and measured. By comparing the intensity signal of the secondary electrons with a reference signal, e.g. corresponding to the same position on the pattern, pattern defects at that position on the wafer are detected. However, due to the increasing demand for higher resolution, it takes a long time to scan the entire surface of a wafer. Therefore, the use of conventional (single-beam) scanning electron microscopes (SEM) for wafer inspection is difficult, as this approach cannot provide the corresponding throughput.

[0004] Wafer and mask defect inspection in semiconductor technology requires high resolution and fast inspection tools covering full wafer or mask applications or hot spot inspection. Due to the limited resolution of optical tools, which cannot handle shrinking defect sizes, the importance of electron beam inspection is increasing. More specifically, from the 20 nm technology node onwards, the high resolution potential of imaging tools based on electron beams is needed to detect all defects of interest.

[0005] As mentioned above, a charged particle multi-beam device and a method for inspecting a sample with an array of sub-beams of charged particles are provided to overcome at least some of the problems in the art. SUMMARY

[0006] In view of the above, charged particle beam devices, charged particle beam device components, methods for inspecting a sample with an array of charged particle sub-beams, and methods of aligning four or more primary sub-beam arrays are provided. Further aspects, advantages and features are apparent from the dependent claims, the description and the drawings.

[0007] According to one embodiment, a charged particle beam device for irradiating or inspecting a sample with an array of primary sub-beams is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam, a multi-aperture lens plate with a plurality of apertures for forming four or more primary sub-beams from the primary charged particle beam, two or more electrodes with one opening for the primary charged particle beam or the four or more primary sub-beams, the two or more electrodes being biasable with the multi-aperture lens plate to provide a focusing effect, a collimator for deflecting a first primary sub-beam, a second primary sub-beam, a third primary sub-beam, and a fourth primary sub-beam of the four or more primary sub-beams relative to each other, a beam separation unit for separating the four or more primary sub-beams from four or more signal sub-beams, a detection unit with detection surfaces, one or more detection surfaces being arranged between beam paths of the four or more primary sub-beams, a scanning deflector assembly for scanning the four or more primary sub-beams over a surface of a sample, an objective lens unit with three or more electrodes, each electrode having an opening for the four or more primary sub-beams, the openings being spaced apart with an opening distance, the objective lens unit being configured to focus the four or more primary sub-beams on the sample and to focus the four or more signal sub-beams on the detection surfaces, and a stage for supporting the sample.

[0008] According to embodiments, a charged particle beam device assembly is provided. The charged particle beam device assembly comprises a first charged particle beam device according to any of the embodiments described herein; and a second charged particle beam device for irradiating or inspecting a sample with a primary beamlet array. The second charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam; a multi-aperture lens plate with a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam; two or more electrodes with one opening for the primary charged particle beam or the four or more primary beamlets (e.g. each electrode has one opening), the two or more electrodes can be biased with the multi-aperture lens plate to provide a focusing effect; a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other; a beam separation unit for separating the four or more primary beamlets from four or more signal beamlets; a detection unit with detection surfaces, one or more detection surfaces are arranged between beam paths of the four or more primary beamlets; a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample; and an objective lens unit with three or more electrodes, each electrode has an opening for the four or more primary beamlets, the openings are spaced apart with an opening distance, the objective lens unit is configured to focus the four or more primary beamlets on the sample and to focus the four or more signal beamlets on the detection surfaces.

[0009] According to embodiments, a method for inspecting a sample with four or more primary beamlets is provided. The method comprises the following steps: generating a primary charged particle beam with a charged particle source; generating four or more primary beamlets with a multi-aperture lens plate and two or more electrodes; deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other with a collimator; scanning the four or more primary beamlets over a surface of the sample with a scanning deflector assembly; focusing the four or more primary beamlets on the sample with an objective lens unit to generate four or more signal beamlets, each electrode of the objective lens unit has an opening for the four or more primary beamlets, the openings are spaced apart with an opening distance; focusing the four or more signal beamlets on detection surfaces, wherein one or more detection surfaces are arranged between respective primary beamlets of the four or more primary beamlets; separating the four or more signal beamlets from the four or more primary beamlets with a beam separation unit to guide the four or more signal beamlets to the detection surfaces.

[0010] According to embodiments, a method of aligning four or more primary beamlet arrays is provided. The method comprises the steps of: generating a primary charged particle beam with a charged particle source; generating four or more primary beamlets with a multi-aperture lens plate and two or more electrodes; deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other using a collimator; controlling an alignment system upstream of the collimator to scan the four or more primary beamlets over openings in an aperture array; and measuring an electrical current at one or more electrically conductive surfaces on the aperture array.

[0011] Embodiments are also directed to devices for implementing the disclosed methods and include means for performing each of the method features. These method features can be performed by hardware components, computer-executed software, any combination thereof, or in any other suitable manner. Furthermore, embodiments are also directed to methods of operating the described devices. Embodiments include method features for performing each of the functions of the devices. BRIEF DESCRIPTION OF DRAWINGS

[0012] For a more detailed understanding of the above features, there is depicted in the accompanying drawings, by way of example, the preferred embodiments. In the drawings:

[0013] Figure 1 schematic diagram of a charged particle beam device for sample inspection according to embodiments described herein;

[0014] Figure 2 schematic diagram of another charged particle beam device for sample inspection according to embodiments described herein;

[0015] Figure 3A and Figure 3B schematic diagram of an aperture lens array of a multi-beam generator according to embodiments of the present disclosure, wherein in particular the aperture lens array is arranged in a deceleration mode;

[0016] Figure 4A schematic diagram of an aperture lens array of a multi-beam generator according to embodiments of the present disclosure, wherein in particular the aperture lens array is arranged in an acceleration mode;

[0017] Figure 4B schematic diagram of an aperture lens array of a multi-beam generator according to embodiments of the present disclosure;

[0018] Figure 5A and Figure 5B schematic diagram of a multi-aperture lens plate (aperture lens array) according to embodiments of the present disclosure;

[0019] Figure 6A and Figure 6BA schematic illustration of a pore of a multi-pore lens plate according to embodiments of the present disclosure;

[0020] Figure 7A A schematic illustration of a collimator with associated components such as a pore array and / or an alignment system according to embodiments of the present disclosure;

[0021] Figure 7B And Figure 7C A schematic illustration of an alignment system according to embodiments of the present disclosure;

[0022] Figure 8A And Figure 8B A schematic side view of a deflector array of a collimator according to embodiments described herein;

[0023] Figure 9 A schematic top view of a deflector array of a collimator according to embodiments described herein;

[0024] Figure 10 A schematic side view of a deflector array of a collimator according to embodiments described herein, e.g. Figure 9 the deflector array shown;

[0025] Figure 11 A schematic illustration of a charged particle beam device according to embodiments of the present disclosure;

[0026] Figure 12 A schematic illustration of a part of a charged particle beam device according to embodiments of the present disclosure, wherein a detection unit and a beam separation unit are described;

[0027] Figure 13 A schematic illustration of a beam separation unit according to embodiments of the present disclosure;

[0028] Figure 14A And Figure 14B A schematic top view and a schematic side view of a magnetic deflector of a beam separator according to embodiments of the present disclosure, respectively;

[0029] Figure 15 A schematic illustration of a beam separation unit according to embodiments of the present disclosure;

[0030] Figures 16A to 16C A schematic illustration of yet another beam separation unit according to embodiments of the present disclosure;

[0031] Figure 17 A schematic illustration of a part of a charged particle beam device according to embodiments of the present disclosure, wherein a detection unit is described;

[0032] Figure 18 A schematic top view of the detection unit shown; Figure 17 the detection unit shown;

[0033] Figure 19 schematic diagram of yet another detection unit according to embodiments of the present disclosure;

[0034] Figures 20A to 20D schematic diagram of an objective lens unit according to embodiments described herein, wherein a modification of the electrodes is described;

[0035] Figure 21 schematic diagram of a stage of a charged particle beam device according to embodiments described herein;

[0036] Figure 22 flowchart of a method of inspecting a specimen with a plurality of primary beamlets in a column of a charged particle beam device;

[0037] Figure 23 schematic diagram of a charged particle beam device assembly combining two or more charged particle beam devices according to the present disclosure;

[0038] Figure 24A and Figure 24B schematic diagram of an aperture array with a conductive surface for current measurement according to embodiments described herein; and

[0039] Figure 25 flowchart of a method of aligning an array of primary beamlets according to embodiments of the present disclosure. DETAILED DESCRIPTION

[0040] Reference will now be made in detail to various embodiments, one or more examples of which are illustrated in the drawings. In the following description, same reference numbers are used to indicate same components. Differences between the various embodiments are described. Each example is provided by way of explanation of the subject matter and is not meant as a limitation of the application. Further, features illustrated or described as part of one embodiment can be used with other embodiments to yield still further embodiments. It is intended that the description includes modifications and variations.

[0041] Without limiting the scope of the protection of the application, in the following, a charged particle beam device or components thereof will be exemplarily referred to as including a primary electron beam and detection of secondary or backscattered particles such as electrons. As described herein, discussions and descriptions regarding detection are exemplarily described with respect to electrons in a scanning electron microscope. Other types of charged particles (e.g., positive ions) can be emitted and / or detected by devices in various different instruments. Embodiments relate to a primary beam of, e.g., electrons, primary beamlets, and one or more signal beams. The primary beam, the primary beamlets, and / or the one or more signal beams can be provided by other charged particles as electrons. Further, the one or more signal beams can include other signals such as, e.g., the above described corpuscles.

[0042] According to embodiments herein, which can be combined with other embodiments, a signal (charged particle) beam or a signal (charged particle) beamlet is referred to as a beam of secondary particles (i.e. secondary and / or backscattered electrons). The signal beam or secondary beam is generated by the primary beam or primary beamlet impinging on the sample or by backscattering of the primary beam or primary beamlet from the sample. The primary charged particle beam or primary charged particle beamlet is generated by a particle beam source and is guided and deflected over the sample to be detected or imaged.

[0043] A “sample” or “specimen” as referred to herein includes, but is not limited to, wafers, semiconductor wafers, semiconductor workpieces, lithography masks, and other workpieces such as memory disks and the like. Embodiments can be applied to any workpiece on which material or structures are deposited. According to some embodiments, which can be combined with other embodiments described herein, the apparatus and method are configured for or applied to e-beam inspection, critical dimension applications, and defect review applications.

[0044] As Figure 1 Exemplarily illustrated, embodiments of the disclosure provide a charged particle beam device 100. The charged particle beam device 100 comprises a multi-beam generator. The multi-beam generator can comprise a charged particle beam source 110, two or more electrodes, and a multi-aperture lens array. The charged particle beam source 110 comprises a particle beam emitter 111 emitting a primary charged particle beam (e.g. an electron beam). According to embodiments described herein, the multi-beam generator is configured to generate an array of primary charged particle beamlets. The charged particle beam source 110 emits a primary beam. The multi-aperture lens array or multi-aperture lens plate 122 generates primary particle beamlets from the primary beam. The one or more electrodes can operate as electrodes of an electrostatic lens with the multi-aperture lens plate. Thus, the one or more electrodes can be lens electrodes. In particular, the one or more electrodes can comprise openings for the primary beam. The multi-aperture lens plate comprises openings for generating the primary beamlets. The one or more electrodes (i.e. the electrodes common to the beamlets) act together with the multi-aperture lens plate, in particular as if the beamlets would be affected by individual lenses corresponding to the openings or apertures in the multi-aperture lens plate.

[0045] A collimator 130 is utilized to collimate the beamlets generated by the multi-aperture lens array. For example, the collimator can comprise Figure 1 The illustrated deflector array acts with one of the lenses. The collimated beamlets can travel substantially parallel to and / or along an optical axis of the objective lens unit 170 onto the sample or specimen 80. One or more further aperture arrays 140 can be provided. For example, an aperture array can be provided downstream of the collimator 130.

[0046] The beam separation unit 160 separates the primary beamlets from one or more signal beamlets (e.g., signal beamlets corresponding to the primary beamlets). The signal beamlets can be detected with the detection unit 150. As an example, some of the detection surfaces 152 are illustrated in Figure 1 According to embodiments described herein, one detection surface can be provided for each signal beamlet, or one detection surface can be provided for each row of signal beamlets.

[0047] The objective lens unit 170 includes a plurality of electrodes having an array of apertures or openings. The plurality of electrodes can act as electrostatic lenses on the beamlets passing through corresponding apertures and openings in the plurality of electrodes. The objective lens unit can be configured as a deceleration lens. The plurality of electrodes can be set to a potential for decelerating the primary beamlets before the primary beamlets impinge on the sample 80.

[0048] The objective lens unit 170 focuses the beamlets (in particular individually) on the sample 80. The sample 80 can be disposed on a stage 180 (e.g., a wafer holder with a drive). The drive can move the sample or specimen in x, y, and z directions, for example.

[0049] Figure 2 Another exemplary embodiment of the charged particle beam device 100 is illustrated. Figure 2 The illustrated dashed boxes illustrate different parts of the charged particle beam device. For example, the box 210 refers to the charged particle beam source 110. The box 220 refers to the combination of the two or more electrodes and the aperture lens array. The box 230 refers to the collimator 130. The box 250 refers to the beam separation unit 160 and the detection unit 150. The box 270 refers to the objective lens unit 170. The box 280 refers to the stage 180. Aspects, features, details, and components will be described in more detail below with reference to the respective boxes. According to embodiments of the present disclosure, more detailed described features, aspects, details, components, modifications, and variations can be combined with each other.

[0050] With regard to Figure 2 , it is understood that the collimator 130 can include the deflector array 132 as described herein and the lens 232 as described herein. Further, the collimator 130 or components associated with the box 230 (i.e., components close to or adjacent to the collimator) can include the alignment deflector system 234 (to be described in more detail below). Further, the charged particle beam device 100 can further include a scanning deflector assembly 271 which can be associated with the box 270. The scanning deflector assembly 271 scans the beamlets over the sample 80, for example, and can be located at or close to the objective lens unit 170.

[0051] In the following, a multi-beam generator is described with regard to Figures 3A to 6B The multi-beam generator includes the charged particle beam source 110, the two or more electrodes, and the aperture lens array.

[0052] Charged particle beam source (internal: block 210)

[0053] According to some embodiments, which can be combined with other embodiments described herein, the charged particle beam source 110 (see also block 210) can comprise an emitter 111. In particular, a single emitter (e.g. a high-brightness emitter) can be provided. The emitter can be of the Schottky type or of the field emitter type, such as a cold field emitter (CFE).

[0054] Schottky or TFE emitters can now measure a reduced brightness of up to 2-10 8 Am -2 (SR) -1 V -1 , whereas CFE emitters have a measured reduced brightness of up to 5-10 9 Am -2 (SR) -1 V -1 . For example, a charged particle beam with at least 5-10 7 Am -2 (SR) -1 V -1 is beneficial. According to embodiments of the present disclosure, a high-brightness emitter is provided. Thus, a beneficial current can be provided for each sub-beam on the sample, such that a signal-to-noise ratio is provided for each sub-beam that allows for a high throughput. For example, according to some embodiments, which can be combined with other embodiments described herein, the emitter can have a brightness of 1-10 8 Am -2 (SR) -1 V -1 to 5-10 8 Am -2 (SR) -1 V -1 , or even higher.

[0055] The charged particle beam emitter described herein can be a cold field emitter (CFE), a Schottky emitter, a TFE, or another high-current high-brightness charged particle beam source, such as an electron beam source. High current is considered to be 5 pA or above per 100 mrad, e.g. up to 5 mA, for example, 30 pA per 100 mrad to 1 mA per 100 mrad, such as about 300 pA per 100 mrad. According to some implementations, the current is substantially uniformly distributed, e.g. with a deviation of +-10%, in particular in case of a linear or rectangular array. According to some embodiments, which can be combined with other embodiments described herein, the primary charged particle beam source or the source of the primary charged particle sub-beams can have a diameter of 2 nm to 100 nm.

[0056] According to still further embodiments, which can be combined with other embodiments described herein, a TFE or another high-reduced-brightness source (e.g., an electron beam source) capable of providing large beam currents is a source whose brightness does not drop by more than 20% of the maximum value when increasing the emission angle to provide a maximum value of 10 μΑ - 100 μΑ (e.g., 30 μΑ).

[0057] In some embodiments, the emitter 11 can be a single thermionic field emitter (preferably of the Schottky type) for emitting a divergent electron beam. The primary beam (i.e., the single primary beam of the single emitter) can be emitted towards the multi-aperture lens plate 122. The multi-apertures are arranged for establishing a plurality of primary sub-beams, one primary sub-beam per aperture.

[0058] According to still further embodiments, which can be combined with other embodiments described herein, the charged particle beam source 110 can comprise at least one of a suppressor 312 and an extractor 314. In case electrons are considered as charged particles of the primary charged particle beam, the suppressor 312 can be at a negative potential compared to the emitter 111. In case electrons are considered as charged particles of the primary charged particle beam, the extractor can be at a positive potential compared to the emitter 111. According to embodiments described herein, the suppressor can control, among others, the current emitted from the emitter and the distribution of the primary beam. The extractor can extract charged particles (such as electrons) from the tip of the emitter 111. Thus, the extractor can provide, for example, an electrostatic field for field emission.

[0059] Figure 3A A schematic diagram illustrating a part of a charged particle beam device with an emitter 111, a suppressor 312 and an extractor 314 is shown. Thus, a charged particle beam source 110 (see also block 210) is provided.

[0060] According to still further embodiments, which can be combined with other embodiments described herein, a first electrode 324 can be provided as an extractor. The first electrode 324 can be arranged to be at a potential at which electrons are emitted from the tip of the emitter 111. Figure 3B The shown first electrode 324 is set to a potential (in particular a potential relative to the potential of the tip of the emitter 111) at which electrons are emitted from the tip. The potential difference for field emission can be, for example, several kilovolts due to the small curvature of the sharp tip and due to the high electric field. For a Schottky-type emitter, the high electric field enhances the thermionic emission of electrons.

[0061] According to some embodiments, which can be combined with other embodiments described herein, the tip of the emitter 111 and the extractor (e.g., the extractor 314 or the first electrode 324) are arranged to be at a distance of less than 1 mm, in particular less than 0.5 mm, in particular less than 0.1 mm. Figure 3A The shown extractor 314 or Figure 3BThe potential difference between the electrodes 324) shown can be 5 keV or more (such as 10 keV or more). The extractor or the first electrode of the two or more electrodes extracts the charged particles from the emitter. Further, the charged particles are accelerated to a high potential within the column. According to some embodiments, a further electrode can be provided to accelerate the charged particles (e.g., to accelerate the electrons with the column). The charged particle energy in the column can be 8 keV or more (in particular at least 15 keV or more).

[0062] Common electrode and aperture lens array (internal: block 220)

[0063] The multi-beam generator comprises two or more electrodes and an aperture lens array. Figure 3A Four electrodes 124 are illustrated with the aperture lens array (i.e., the multi-aperture lens plate 122). According to some embodiments, which can be combined with other embodiments described herein, 2 to 6 electrodes (in particular electrostatic electrodes) and a multi-aperture lens plate can be provided. The multi-aperture lens plate comprises a plurality of apertures. The aperture lens array (ALA) or multi-aperture plate generates one primary beamlet for each aperture.

[0064] The aperture lens array is downstream of the charged particle beam source 110, the aperture array separates the divergent primary charged particle beam into a plurality of primary charged particle beamlets. Further, the lens generated for the beamlets by the electrodes and the multi-aperture lens plate focus each individual primary charged particle beamlet in a plane (indicated by the plane 222 in Figure 3A The plane 222 is downstream of the multi-aperture lens plate (i.e., the multi-aperture lens plate 122 is between the plane 222 and the emitter 111).

[0065] Thus, the charged particle beam source and the ALA constitute a multi-beam generator for establishing a plurality of primary charged particle beamlets which are directed towards the surface of the sample. The aperture lens array (i.e., the multi-aperture lens plate) interacts with the two or more electrodes 124. The two or more electrodes and the aperture lens plate are biased to form electrostatic lens fields for the primary beams or to generate the primary beamlets, respectively. I.e., the two or more electrodes and the aperture plate generate a plurality of virtual beam sources corresponding to the beamlets.

[0066] According to some embodiments, as Figure 3AAs shown, the two or more electrodes 124 can be provided downstream of the multi-aperture lens plate 122. In other words, the two or more electrodes 124 are each disposed between the multi-aperture lens plate 122 and the charged particle beam source and / or emitter 111. The two or more electrodes are operated in deceleration mode. According to a still further embodiment, which can be combined with other embodiments described herein, the two or more electrodes 124 can be downstream of the multi-aperture lens plate 122. In other words, the multi-aperture lens plate 122 can be between the two or more electrodes 124 and the charged particle beam source and / or emitter. Thus, the two or more electrodes are operated in acceleration mode. That is, for example, the two or more electrodes are operated in acceleration mode, as exemplarily illustrated in Figure 4A According to a still further embodiment, as exemplarily illustrated in Figure 4B two or more electrodes 124 can be provided. The multi-aperture lens plate can be disposed between two of the two or more electrodes 124. According to embodiments of the present disclosure, the two or more electrodes 124 can have an aperture opening through which the primary charged particle beam can pass. For example, each of the two or more electrodes can have one opening through which the primary charged particle beam can pass, or each of the two or more electrodes can have one opening through which the primary beamlets can pass, with respect to the electrodes downstream of the multi-aperture lens plate.

[0067] Figure 3B Further modifications of the aperture array, which can be combined with other embodiments of the present disclosure, are illustrated. A heater for the multi-aperture lens plate 122 is provided. The heater can comprise a power source 322. For example, the power source can provide an electric current for the heater disposed at the multi-aperture lens plate 122. For example, a heating element can be attached to or embedded in the multi-aperture lens plate. The heating of the multi-aperture lens plate allows for the removal of contaminants. The multi-aperture lens plate blocks a portion of the charged particle beam, i.e. the primary beam. Further, the apertures of the multi-aperture lens plate can provide beam limiting apertures to form beamlets. Thus, contamination at the apertures can lead to a deterioration of the beamlet formation. Thus, the removal of contaminants, e.g. by heating, provides for an improved charged particle beam device and / or can reduce the need for maintenance.

[0068] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of a sample and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The openings are spaced apart with an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some implementations, the objective lens unit can be further configured to focus the four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. Further, a heater for heating the multi-aperture lens plate is provided. Heating the multi-aperture lens plate allows to prevent and / or remove contamination (in particular to the beam limiting apertures of the multi-aperture lens plate) and thus reduces maintenance.

[0069] According to some embodiments, which can be combined with other embodiments described herein, at least two electrodes 124 and at least one extractor are provided which interact with the multi-aperture lens plate 122. The size (i.e. diameter) of the respective openings in the electrodes 124 can be varied. Further, the potential of the extractor, the two or more electrodes, and the multi-aperture lens plate can be controlled independently. Adapting the distance between the electrodes, the opening size, and the potential allows to control the aberrations of the primary beamlets at the collimator and the pitch of the primary beamlets. It should be noted that according to some embodiments, the distance and the opening size are designed to be determined and set after manufacturing. Thus, for a specific design, the potential can be varied during operation, while other parameters can not be varied, e.g. during operation. According to still further embodiments, which can be combined with other embodiments described herein, the disadvantage that the pitch or the field curvature cannot be controlled due to only two electrodes between the extractor and the aperture plate can be overcome by providing more than two electrodes. Thus, having three or more electrodes allows to match the pitch of the beamlets to the pitch of the collimator (i.e. the openings in the collimator 130 shown). Figure 1

[0070] For example, a field curvature correction can be provided such that the focal points of the plurality of primary beamlets lie in a plane perpendicular to the optical axis of the charged particle beam device or in a plane parallel to the collimator (e.g.​Figure 3A The plane 222) shown.

[0071] According to some embodiments of illuminating a sample or inspecting a sample, the following operations can be provided. A primary charged particle beam is extracted from a charged particle beam source with an extractor. The primary charged particle beam is accelerated after the extractor. The primary charged particle beam is decelerated towards a multi-aperture lens plate with two or more electrodes. For example, a first electrostatic field between a last electrode of the two or more electrodes upstream of the multi-aperture lens plate and the multi-aperture lens plate is smaller than a second electrostatic field between a penultimate electrode of the two or more electrodes and the last electrode. As described above, more specifically, by additionally providing appropriate diameters of the two or more electrodes 124, the deceleration and optional acceleration can be set such that the Cs and Cc of the lens formed by the multi-aperture lens plate and the two or more electrodes are minimized and such that the pitch of the four or more primary sub-beams at the collimator matches the collimator pitch of the collimator. Furthermore, additionally, the deceleration and optional acceleration can be set such that the field curvature at the collimator is zero. Cc is the chromatic aberration coefficient of the lens, while Cs is the spherical aberration coefficient of the lens.

[0072] According to still further embodiments, which can be combined with other embodiments described herein, an extractor 314, three or more electrodes 124, such as for example, 5 electrodes, and a multi-aperture lens plate 122 can be provided. For example, four electrodes 124 can be provided upstream of the multi-aperture lens plate 122 and one electrode 124 can be provided downstream of the multi-aperture lens plate 122. Providing more than two electrodes 124 can provide at least one additional degree of freedom for control of the primary sub-beams. Thus, the plane 222 (see Figure 3A ) at which each individual primary charged particle sub-beam is focused can be moved along the length of the column. For example, the focal point of the primary sub-beams (see, for example, the plane 22 in Figure 3A ) can be adapted downstream of the collimator.

[0073] According to still further embodiments, which can be combined with other embodiments described herein, moving the focal point of the primary sub-beams allows control of the magnification for the source on the sample.

[0074] The aperture lens array comprises at least one aperture opening for each sub-beam. The aperture openings can be located on the multi-aperture lens plate 122 in any array configuration, such as a straight line, a rectangle, a square, a ring, or any suitable one- or two-dimensional array. For example, the sub-beam array can be arranged in a straight line, a rectangle, or a square.

[0075] When the porous lens plate 122 is irradiated with a primary charged particle beam, several focused primary charged particle sub-beams are established by using, for example, a deceleration field in front of the porous lens plate. An array of lenses or deflectors can be arranged in the focal plane of the primary charged particle sub-beams. In the accompanying drawings, some primary charged particle sub-beams are shown behind the lenses in the array, while other primary charged particle sub-beams are omitted for better overview in the drawings.

[0076] In some embodiments, the porous lens plate 122 can be directly irradiated by the charged particle beam emitter 111. According to some embodiments, "directly" can mean—in embodiments having two or more electrodes having field curvature correction electrodes (viewed from the direction of the propagating primary charged particle beam) in front of the porous lens plate—no additional optical elements are disposed between the charged particle beam emitter 111 and the porous lens plate. The porous lens plate separates the primary charged particle beam emitted from the charged particle beam emitter into an array of primary charged particle sub-beams. For example, the porous lens plate has at least three aperture openings for separating the primary charged particle beam into at least three primary charged particle sub-beams. Figure 1 In the example shown, the schematic diagram illustrates seven primary charged particle sub-beams. In some embodiments, the primary charged particle sub-beams may be arranged in a one-dimensional (linear) array or a two-dimensional array (e.g., 4×4, 3×3, 5×5) or a rectangular array (e.g., 2×5). The embodiments described herein are not limited to the array example and may include any suitable array configuration of primary charged particle sub-beams.

[0077] The porous lens plate can be advantageously used in other embodiments relating to charged particle beam devices, systems including arrays of charged particle beam devices, and methods of operating charged particle beam devices. The design of the porous lens plate advantageously follows different criteria and must be considered within the context of the overall charged particle beam path design. In some embodiments that can be combined with other embodiments described herein, the porous lens plate may have one or more of the following features: The number of apertures is a trade-off between the maximum possible total current and optical performance (particularly the spot size achievable in the maximum possible sub-beam field). Another boundary condition is sub-beam separation on the sample, which ensures signal sub-beam separation on the detector, where crosstalk is reduced or avoided. According to further embodiments that can be combined with other embodiments described herein, a grid configuration (i.e., the location of the primary sub-beams on the sample and / or the location of the aperture openings in the porous plate) is provided to allow complete coverage of the area of ​​the substrate surface during scanning. The coverage is not limited to, for example, a pure charged particle sub-beam scan in the xy direction, but also includes mixed scan operations, such as charged particle sub-beam scans in a first direction (such as the x direction) and platform movement in another direction (such as the y direction) different from the first direction.

[0078] Figure 5A and Figure 5B An example of a multi-aperture lens plate 122 is illustrated in accordance with embodiments of the present disclosure. Further, Figures 6A to 6B Modifications of the aperture openings of a multi-aperture lens plate are illustrated. The modifications of the multi-aperture lens plate and / or aperture openings can be combined with other embodiments described herein. Figure 5A A multi-aperture lens plate 122 with aperture openings 522 is illustrated. The aperture openings are arranged in an array. In accordance with some embodiments, a square array or square pattern of aperture openings can be provided. As described above, other arrays or patterns can be provided. For example, Figure 5A A 3x3 array of aperture openings 522 is illustrated. Additional openings 524 are provided for the multi-aperture lens plate. The additional openings 524 can be considered dummy openings. Even though additional sub-beams can be generated from the additional openings 524, the additional sub-beams are not used for image generation. The additional openings provide neighboring openings for the aperture openings 522. Accordingly, aperture openings 522 that do not have a neighboring aperture opening on each side of a minimum number of openings are provided with a neighboring additional opening to have a symmetric characteristic (particularly for aperture openings that generate primary sub-beams for image generation). As described above, the sextupole effect or sextupole aberration that can occur for aperture openings that do not have a neighboring opening can be reduced.

[0079] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of a sample and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The openings are spaced apart with an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some implementations, the objective lens unit can be further configured to focus the four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. According to some embodiments, the plurality of apertures of the multi-aperture lens plate form an aperture array, wherein the number of apertures in the aperture array is greater than the number of primary beamlets impinging on the sample. Providing more aperture openings than primary beamlets impinging on the sample allows for a reduced aberration, in particular a reduced octupole aberration, for the primary beamlets at the periphery of the primary beamlet array.

[0080] According to some embodiments, which can be combined with other embodiments described herein, an array or pattern of aperture openings can be provided in a square or rectangular pattern. Further, a hexagonal pattern of aperture openings can be provided. The hexagonal pattern can be considered a honeycomb pattern.

[0081] As described above, the throughput for inspecting semiconductor wafers and other applications is advantageously increased. Therefore, a multi-beam column is proposed according to embodiments of the present disclosure. In order to further increase the throughput, the total current of the plurality of beamlets on the sample is advantageously increased. Therefore, the sum of the areas of the aperture openings 522 is large compared to the area of the multi-aperture lens plate or the area irradiated by the primary charged particle beam. Therefore, the size of the openings is advantageously large. According to some embodiments, which can be combined with other embodiments described herein, the diameter of the aperture openings can be 60% or more compared to the pitch (e.g. center-to-center distance) of the aperture openings. For example, the diameter of the aperture openings can be 70% or more compared to the pitch of the aperture openings.

[0082] As described with respect to Figure 6BAs shown, the aperture openings can have a circular shape and thus a defined diameter. According to a still further embodiment, the aperture openings can have a different shape. Accordingly, the size of the aperture openings can be 60% or more, in particular 70% or more, of the pitch of the aperture openings. For example, the size of the aperture openings can be the smallest size of the aperture openings in any direction. For example, a square aperture opening has the size of one side of the square, while a rectangular aperture opening has the size of the smaller side of the rectangle.

[0083] According to a still further embodiment, which can be combined with other embodiments described herein, the size and shape of the aperture openings can be arranged to have an open area (i.e. the sum of the open areas) of 50% or more, in particular 70% or more, of the area of the multi-aperture lens within the array of openings.

[0084] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam, wherein a size of the apertures in a first direction is at least 70% of a pitch of the apertures in the first direction. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, the two or more electrodes can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The openings are spaced apart by an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some implementations, the objective lens unit can be further configured to focus the four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. Providing apertures with a relatively large size increases the sum of the aperture openings, which increases the total beam current of the primary beamlets on the sample. Thus, the signal-to-noise ratio for imaging can be increased.

[0085] Figure 5B An alternative arrangement of aperture openings 522 on the multi-aperture lens plate 122 is illustrated. The aperture openings can be arranged in a circle. This can reduce off-axis operation of optical elements common to the primary charged particle beam or the primary charged particle beamlets.

[0086] Figure 6A An embodiment of a pore opening 522 is illustrated. According to some embodiments, which can be combined with other embodiments described herein, the pore opening can have a square shape or a substantially square shape. The octupole effect or octupole aberration that can occur with a circular pore opening can be reduced by the square shape or substantially square shape. Further, the shape of the pore opening can be substantially square and can include side edges 622 of the pore opening. The side edges, in particular the four side edges, can have the same length. The corners 623 can be rounded. Thus, the average opening can be a square with rounded edges at the corners. The rounded corners can further reduce the octupole effect or octupole aberration.

[0087] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-pore lens plate having a plurality of pores for forming four or more primary beamlets from the primary charged particle beam, wherein the shape of the plurality of pores is a square with rounded corners. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-pore lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The openings are spaced apart by an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some embodiments, the objective lens unit can be further configured to focus four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. The square shape with rounded corners of the openings reduces aberrations, in particular octupole aberrations, for the primary beamlets.

[0088] Collimator and multi-aperture (internal: block 230)

[0089] According to embodiments of the present disclosure, which can be combined with other embodiments described herein, a collimator 130 and associated components can be provided downstream of the ALA. The collimator 130 collimates the beamlets. Thus, the diverging pattern or array of primary beamlets is redirected by the collimator 130. For example, after the collimator, the primary beamlets can be parallel or substantially parallel. According to some embodiments, which can be combined with other embodiments described herein, the collimator 130 can be provided downstream of the ALA and upstream of the objective lens unit 120. The collimator 130 can be provided downstream of the ALA and upstream of the objective lens unit 120. Figure 3AThe plane 222 is shown in or near the focal plane of the ALA. Near the focal plane is to be understood as within 20% of the focal length of the ALA. By arranging the plane 222 in or near the collimator (i.e. in the focal plane of the ALA), distortions of the individual electron beams due to aberrations of the deflection can be reduced.

[0090] According to a still further embodiment, as described above, the magnification control can be provided by moving the plane 222 downstream of the ALA.

[0091] As Figure 7A shown, the collimator can comprise a deflector array 132 and a lens 232. According to a still further modification, the collimator can comprise a deflector array or, alternatively, the lens 232. As described herein, the collimator (which can also be denoted as collimator deflection structure) is configured such that the primary beamlets from the aperture lens array are emitted from the collimator parallel with respect to each other.

[0092] According to some embodiments, which can be combined with other embodiments described herein, each beamlet can be deflected by a separate deflection electrode. Figure 8A and Figure 8B An exemplary deflection electrode is illustrated. Figure 8A An array of deflection electrodes 812 is illustrated. A pair of deflection electrodes is provided for the x-direction and the y-direction. Thus, collimation can be provided individually for each beam. For example, the deflection electrodes can be provided as micro electro-mechanical systems (MEMS) and can be provided on a wafer.

[0093] According to embodiments of the present disclosure, which can be combined with embodiments described herein, a plurality (e.g. 4 or 8) of deflection electrodes can be provided for each primary beamlet. Each primary beamlet can be deflected individually. The collimator deflection structure can comprise a segmented collimator. The collimator deflection structure can comprise a segmented deflector for each of the primary beamlets.

[0094] According to a still further embodiment, as Figure 8A illustrated exemplarily, one or more deflector arrays can be provided along the axis of the charged particle beam column. For example, a deflector or a stack of deflector arrays can be provided on one or more wafers, such that the alignment of the individual deflection electrodes for each beamlet can be simplified. For example, a first deflection electrode 812 can deflect the beamlet in the x-direction, a second deflection electrode 814 can deflect the beamlet in the y-direction, and a third deflection electrode 816 can provide an aberration correction (e.g. correct for astigmatism).

[0095] According to a still further modification, which can be combined with other embodiments described herein, the deflector array for collimating the primary beamlets can be provided by pairs of electrodes deflecting two or more primary beamlets. For example, Figure 9An elongated electrode 912 is illustrated for deflecting a row of primary beamlets along the Y direction and an elongated electrode 914 is illustrated for deflecting a row of primary beamlets along the x direction. Figure 9 A top view of the deflector array 132 of the collimator 130 is illustrated. Figure 10 A side view of the deflector array is illustrated. For example, an elongated electrode 912 is illustrated as well as a distribution electrode 914. In addition, individual deflectors similar to Figure 8A and Figure 8B can be provided. Individual electrodes can be provided for fine adjustment of collimation or aberration correction.

[0096] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with an array of primary charged particle beamlets is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes are provided having one opening for the primary charged particle beam or for the four or more primary beamlets (e.g. each electrode has one opening), the two or more electrodes can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample and an objective lens unit having three or more electrodes each having an opening for the four or more primary beamlets. The openings are spaced apart by an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some embodiments, the objective lens unit can be further configured to focus four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. According to some embodiments, the collimator comprises two or more first elongated electrodes for deflecting a row of four or more primary beamlets along a first direction and two or more second elongated electrodes for deflecting a column of four or more primary beamlets along a second direction, the second direction being different from the first direction. Thus, the array of primary charged particle beamlets can be guided with a reduced number of electrodes, which in turn results in a reduced number of power supplies and power supply connections.

[0097] The individual deflectors of the deflector array can be realized by at least four-pole (quadrupole) multi-pole elements. According to some embodiments, the multi-pole elements can be manufactured by conventional mechanical machining. According to a particular embodiment, which can be combined with other embodiments described herein, micro-electro-mechanical system (MEMS) technology deflector elements can be beneficial, as they allow for a higher multi-pole density and simplify the wiring of the electrodes.

[0098] As described above and as shown in Figure 7A According to some embodiments to be described in detail below, the deflector array 132 is arranged within or near the lens. According to some embodiments, the deflector array being arranged "in or near the lens" or "within the lens" can be understood as the deflector array being placed within the focal length of the lens. More specifically, the deflector array can be placed within the lens. For example, the lens can comprise three electrodes, and the deflector array can be placed between two of the three electrodes. According to some embodiments, the deflector array can be placed substantially at the height of the middle electrode of the three electrodes of the lens.

[0099] According to some embodiments, the lens can be used to achieve the main effect of deflecting the primary charged particle sub-beams, in particular for collimating the primary sub-beams to exit the collimator substantially parallel. The deflector array 132 can be used to fine-tune the individual primary charged particle sub-beams, in particular to fine-tune the primary charged particle sub-beams that are directed into or through the coma-free point of the objective. The charged particle beam device can comprise a controller (e.g. a controller connected or integrated in a feedback loop or a monitoring device for monitoring the operation of the charged particle beam device) for controlling the operating parameters of the lens and the deflector array.

[0100] According to some embodiments, which can be combined with other embodiments described herein, a lens 232 can be provided instead of the deflector array 132. For example, the lens can comprise three electrodes.

[0101] According to some embodiments, the lens 232 can be an acceleration lens (in particular in case two or more electrodes are driven in deceleration mode and / or two or more electrodes are arranged in front of (from the propagation direction of the primary charged particle beam) the multi-aperture lens plate). In some embodiments, the lens 232 provided as an acceleration lens (or in other embodiments as a deceleration lens) can be an electrostatic lens or a combined magnetic electrostatic lens.

[0102] According to embodiments described herein, the primary charged particle sub-beams are directed towards the lens 232. For example, the lens 232 can be an acceleration lens for accelerating the primary charged particle sub-beams propagating from the multi-aperture lens plate. In embodiments where two or more electrodes are placed in front of the multi-aperture lens plate in the direction of the propagating primary charged particle beam, the lens 232 can be used to accelerate the primary charged particle sub-beams to a high column voltage. For example, the acceleration lens can accelerate the primary charged particle sub-beams to a column voltage of typically 10 kV or above (and more typically 20 kV or above). The acceleration voltage can determine the speed of the charged particles of the charged particle sub-beams to travel down the column. In one example, the acceleration lens can be an electrostatic lens.

[0103] According to a further modification of the components in block 230, which can be combined with other embodiments described herein, an alignment deflector system 234 can be provided. For example, a coil can be provided between the pinhole lens array and the collimator 130. The coil can produce positioning of the primary beamlets on the collimator pinholes and / or can rotate the primary beamlet array. Additionally or alternatively, a quadrupole field can be provided for correcting the pitch of the primary beamlet array in the x-direction and / or the y-direction.

[0104] Figure 7A An alignment deflector 716 is illustrated which acts on a plurality of primary beamlets. Figure 7A An alignment deflector is illustrated for a first direction. A further alignment deflector can be provided for a different second direction (e.g. orthogonal to the first direction). Additionally, an alignment coil is provided for rotating the primary beamlet array. The alignment deflector 716 can provide a deflection field (dipole field) in the x-direction, in the y-direction, or a combination thereof. Additionally, the alignment deflector 716 can provide a quadrupole field acting on the primary beamlet array. Thus, the pitch of the primary beamlet array can be adjusted or aligned in the x-direction and / or the y-direction.

[0105] Although Figure 7A The alignment deflector 716 is illustrated with a magnetic deflector, however, the alignment deflector system can also be provided with an electrostatic deflector or a combination of a magnetic deflector and an electrostatic deflector.

[0106] Figure 7B An array of primary beamlets 701 at the alignment system 710 is illustrated. The alignment system can comprise two alignment coils for producing a first quadrupole field in a first direction (see arrows in Figure 7B The alignment system can comprise two further alignment coils (i.e. alignment deflector 716) for producing a second quadrupole field in a second direction. The first direction can be rotated by about 45° from the second direction. Thus, the shape of the array of primary beamlets 701 can be adapted. That is, the pitch of the primary beamlets can be adapted in two directions (e.g. the directions are rotated by 45° to adjust for distortions on the primary beamlet array). The quadrupole field can be provided to correct the pitch of the primary beamlet array in the x-direction and / or the y-direction. The quadrupole field can squeeze the array in one direction and spread the array in the orthogonal direction to adapt the pitch of the primary beamlets. Thus, a deflection and / or squeezing of the beamlet array can be provided.

[0107] Figure 7CAn implementation of an alignment system is illustrated in accordance with some embodiments. For example, a core 796 can be provided. The core has an opening for letting a primary beamlet array pass through the opening of the core. A plurality of alignment coils (i.e., alignment deflector 716) can be provided at the core 796, such as all deflection alignment coils for setting the quadrupole field(s). Thus, a field with a dipole part and a quadrupole part for combined deflection of the array and pitch adjustment of the array can be provided.

[0108] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes (e.g., each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The openings are spaced apart by an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some embodiments, the objective lens unit can be further configured to focus four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. The charged particle beam device further comprises an alignment system provided between the multi-aperture lens plate and the collimator, wherein the alignment system comprises at least one quadrupole to adapt a pitch between the four or more primary beamlets. Thus, the pitch of the primary beamlets of the primary beamlet array can be adjusted at the collimator.

[0109] According to still further embodiments, which can be combined with other embodiments described herein, one or more further aperture arrays 140 can be provided. For example, Figure 7A A first aperture array 140 downstream of the collimator 130 and a second aperture array 740 upstream of the collimator 130 are illustrated. According to some embodiments, which can be combined with other embodiments described herein, aperture arrays can be provided on both sides of the collimator. As Figure 7A Exemplarily, the number of openings in the aperture array 140 and / or the number of apertures of the array 740 is smaller compared to the number of aperture openings in the multi-aperture lens plate 122. As outlined above with respect to Figure 5AThe aperture openings 522 for the primary beamlets can be provided with dummy openings 524, such as dummy apertures. The dummy apertures reduce aberrations of the ALA. The dummy apertures are not intended for use in producing primary beamlets that impinge on the sample. Thus, the aperture array 740 can include portions for blocking charged particle beams that pass through the dummy openings 524. Thus, the multi-aperture lens plate includes more openings than the number of openings in one or more additional aperture arrays or than the openings in the deflector array of the collimator.

[0110] Figure 7A Further embodiments are illustrated that can be combined with other embodiments described herein, in particular embodiments with an alignment system 710. The aperture array 740 includes a conductive material 742. The conductive material 742 or conductive surface allows for measuring a current that can be provided by impinging the primary beamlets on the aperture array. The current can be measured using a current meter 744. Thus, misalignment of the one or more primary beamlets with respect to the collimator 130 can be detected based on the charged particles impinging on the conductive material. A measured current of zero corresponds to all primary beamlets being directed through openings in the additional aperture array 740. According to some embodiments, which can be combined with other embodiments described herein, the alignment system 710 can allow for adjustments in 4 degrees of freedom, e.g., based on the current measurement. Deflections in the x-direction, deflections in the y-direction, rotations around the z-axis, and pitch adjustments can be provided by the quadrupole fields.

[0111] According to further embodiments, the conductive material 742 or conductive surface can include segments or portions of conductive material, wherein each segment or portion corresponds to an individual opening in the aperture array or a pattern, e.g., a row or column, of openings in the aperture array. Thus, the ability to measure a current for individual openings or patterns of openings can be used to further improve alignment of the primary beamlets with the alignment system 710.

[0112] Reference can be made to Figure 24A and Figure 24B Further implementations of current measurements on aperture plates are described, in particular for alignment of primary beamlets with the alignment system described with respect to Figures 7A to 7C . Figure 24A An aperture array 740 is illustrated. A plurality of aperture openings is provided in the aperture array and forms an array of openings indicated by the dashed lines 703. The aperture has a plate and a conductive surface or area of the conductive material 742 is provided on the plate. Figure 24AFour conductive surfaces are illustrated as indicated by dashed lines. The four conductive surfaces can be insulated from each other. A galvanometer can be connected to the conductive surfaces. A well-aligned primary beamlet array passes through the openings in the aperture array. Thus, for a well-aligned array, no current of charged particles from the primary beamlets is generated. Depending on the number of primary beamlets impinging on the conductive surfaces (i.e. the conductive material 742), the current in the galvanometer 744 increases. Thus, the more primary beamlets impinge on the conductive surfaces, the greater the current.

[0113] According to some embodiments, which can be combined with other embodiments described herein, the conductive material 742 on the aperture array 740 can be segmented (e.g. four conductive surfaces can be provided). When controlling the alignment system, in which one or more primary beamlets are moved relative to the openings of the aperture array, the current in one or more galvanometers 744 changes. According to the relative movement of the primary beamlets, the current in each of the galvanometers can be determined. Thus, moving the primary beamlet array (e.g. to the right of Figure 24A the illustrated embodiments, the segmentation of the conductive material and connecting galvanometers to segments of the conductive material allows determining different currents in each of the galvanometers. Thus, moving the primary beamlet array (e.g. to the right of Figure 24A the illustrated embodiments, the segmentation of the conductive material and connecting galvanometers to segments of the conductive material allows determining different currents in each of the galvanometers. Thus, moving the primary beamlet array (e.g. to the right of

[0114] According to another implementation, which can be additionally or alternatively provided, one or more conductive surfaces can be provided on the aperture plate and outside of the array of openings indicated by dashed lines 703.

[0115] For example, a conductive surface can be provided adjacent to one corner of the array of openings. Exemplarily, this can be the upper right conductive surface or the corresponding conductive material 742 as illustrated. Figure 24B Figure 24B Further, a close-up of the upper right primary beamlet is illustrated. Scanning the primary beamlet array indicated by arrow 749 can direct the upper right primary beamlet onto a conductive surface (e.g. the conductive surface adjacent to the corresponding corner of the primary beamlet array). A galvanometer 744 can be utilized to measure the current. Thus, by scanning the primary beamlet array, the amount of deflection of the primary beamlet array can be determined such that the current can be detected. A corresponding deflection can be provided for a number of primary beamlets, in particular the primary beamlets at the corners of the primary beamlet array.

[0116] ​Scan corners (e.g., on conductive surfaces) Figure 24B Each of the four corners of the array shown can be used to determine the position of each corner. According to the embodiments described herein, the scanning can be configured such that the corresponding sub-beam strikes the conductive surface before other sub-beams strike it. According to one embodiment, two or more corner sub-beams can be guided onto the same conductive surface. According to an alternative embodiment, each corner sub-beam can be guided to a different conductive surface. For example, refer to... Figure 24B Each corner sub-bundle can be guided to the conductive material 742 (i.e., the corresponding conductive surface adjacent to the corresponding corner).

[0117] According to some embodiments that can be combined with other embodiments described herein, determining the control parameters of the alignment system for at least three corners allows for the evaluation of the scan position of the primary sub-beam array, potential distortions on the primary sub-beam array, and potential rotational orientation of the primary sub-beam array. Therefore, according to embodiments of this disclosure, the combination of the alignment system 710 and one or more galvanometers connected to one or more conductive surfaces on the aperture array allows for proper alignment of the primary sub-beam array relative to the aperture array.

[0118] Figure 25 The diagram illustrates a flowchart of a corresponding method for aligning a primary sub-beam array. At operation 1252, a primary charged particle beam is generated using a charged particle source. At operation 1254, four or more primary sub-beams are generated using a porous lens plate and two or more electrodes. This document describes a method for aligning regions of primary sub-beams with respect to embodiments, wherein a single source generates the primary charged particle beam, and the primary sub-beams are generated via a porous lens array. According to further embodiments that can be combined with other embodiments described herein, alignment of the primary sub-beam array can be similarly provided for an array of primary sub-beams generated by an array of charged particle beam sources.

[0119] At operation 1256, a collimator is used to deflect the first, second, third, and fourth primary sub-bundles of four or more primary sub-bundles relative to each other. At operation 1257, the alignment system upstream of the collimator is controlled to scan the four or more primary sub-bundles over the openings of the aperture array. Furthermore, at operation 1258, the current at one or more conductive surfaces on the aperture array is measured.

[0120] According to relative to Figure 24A The described embodiments allow for control of the alignment system to minimize current at one or more conductive surfaces. For example, one or more conductive surfaces can be positioned between openings in an array of apertures. Additionally or alternatively, such as relative to... Figure 24BAs described, the alignment system can be controlled to increase the current at one or more of the electrically conductive surfaces. In such embodiments, the one or more electrically conductive surfaces are disposed outside of the array of openings formed by the openings in the array of apertures. According to still further embodiments, which can be combined with other embodiments described herein, after the array of primary beamlets is aligned relative to the array of apertures, the primary beamlets or at least a portion of the primary beamlets can reach the sample, and a signal from the signal beamlets can be measured. By increasing the signal of the signal beamlets, the array of primary beamlets can be further aligned downstream of the array of apertures. For example, further alignment can be provided by adjustment of individual deflections of the primary beamlets in the alignment system and / or the collimator.

[0121] The four methods of aligning the array of primary beamlets, the control of the alignment system can comprise one or more of the following control procedures: a) scanning the four or more primary beamlets in a first direction in the plane of the aperture plate with a deflection field, in particular one deflection field; b) scanning the four or more primary beamlets in a second direction in the plane of the aperture plate perpendicular to the first direction; c) adapting the pitch between the four or more primary beamlets in a third direction in the plane of the aperture plate with a quadrupole field; d) adapting the pitch between the four or more primary beamlets in a fourth direction in the plane of the aperture plate with a quadrupole field; e) rotating the array formed by the four or more primary beamlets in the plane of the aperture plate. Control procedure a) and / or b), control procedure c) and / or d), and control procedure e) can be performed sequentially. Furthermore, the control procedures can be performed sequentially in an iterative manner.

[0122] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of a sample and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets. The openings are spaced apart with an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some implementations, the objective lens unit can be further configured to focus the four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. According to some embodiments, the collimator is arranged between a first aperture array of the one or more aperture arrays and a second aperture array of the one or more aperture arrays, and in particular, a galvanometer is attached to at least one aperture array of the one or more aperture arrays. Thus, a beam adjustment of the primary beamlets at the collimator can be measured. Further, the first aperture array above the collimator and the second aperture array below the collimator allow a confinement of the field (e.g. electrostatic field of the collimator). Further, additionally or alternatively, the aperture arrays and the corresponding holders of the aperture arrays can act as a vacuum separation between the vacuum compartments. The openings in the aperture arrays can act as pumping apertures.

[0123] According to still further embodiments, which can be combined with other embodiments described herein, at least one of the one or more further aperture arrays can be provided to separate the vacuum in adjacent vacuum compartments. Figure 11 A charged particle beam device 100 is illustrated. A charged particle beam source 110 is arranged in a first vacuum compartment 118. A vacuum pump 119 is arranged in fluid communication with the vacuum compartment 118. The vacuum pump 119 evacuates the vacuum compartment 118. In Figure 11 In the illustrated example, the aperture lens array or the multi-aperture lens plate is arranged in the vacuum compartment 118, respectively. According to still further embodiments, two vacuum compartments can be provided instead of the vacuum compartment 118. Thus, the charged particle beam source 110 and the aperture lens array can be arranged in separate compartments.

[0124] As Figure 11As shown, a second vacuum compartment 138 can be provided. For example, the collimator 130 can be provided in the second vacuum compartment 138. According to a further modification, the pinhole lens array can also be provided in the second vacuum compartment 138. A vacuum pump 139 is provided in fluid communication with the second vacuum compartment 138. The vacuum pump 139 evacuates the vacuum compartment 138.

[0125] According to some embodiments, which can be combined with other embodiments described herein, a holder 149 for a further pinhole array 140 is provided. The holder 149, and in particular the holder 149 with the pinhole array 140, separates the second vacuum compartment 138 from a third vacuum compartment 188. Thus, differential pumping of different vacuum compartments on opposite sides of the holder and / or the further pinhole array 140 cannot be provided.

[0126] The third vacuum compartment 188 is in fluid communication with a vacuum pump 189. The third vacuum compartment can comprise the objective lens unit 170. Further, the stage 180 can be provided in the third vacuum compartment 188. According to some embodiments, which can be combined with other embodiments described herein, at least three vacuum compartments can be provided in the charged particle beam device 100. Two adjacent vacuum compartments can be separated from each other by a further pinhole array and / or a holder for a further pinhole array. Having three or more vacuum compartments allows for regions of different pressure within the column of the charged particle beam device 100.

[0127] Embodiments of a charged particle beam device according to the present disclosure provide for illumination of a sample with a plurality of primary beams, wherein the primary beams are generated from a single charged particle beam source, e.g. with ALA. According to further embodiments, which can be combined with other embodiments described herein, the primary beams travel through the charged particle beam device without the first primary beam of the primary beam array crossing the second primary beam of the primary beam array, in particular without the primary beams generated by the charged particle beam device crossing. Avoiding crossings is for avoiding interactions between the primary beams. Greater beam currents can be provided for the primary beams.

[0128] Beam splitting and detection (internal: block 250)

[0129] Reference is made to Figure 2 The beam separation unit 160 and the detection unit 150 are described in further detail below with reference to block 250. The beam separation unit 160 separates the primary beam from the one or more signal beams. The signal beams are detected by the detection unit 150. Figure 12 The sample 80 is illustrated. The primary beam 103 impinges on the sample 80. After impingement of the primary beam 103, the signal beam 105 is generated. The primary beam 103 and the signal beam 105 are separated by the beam separation unit.

[0130] According to some embodiments, which can be combined with other embodiments described herein, the beam separation unit can be a Wien filter array with a magnetic deflector 162 and an electrostatic deflector 164. The deflection of the primary beamlets by the magnetic deflector 162 is arranged in a direction opposite to the deflection direction of the electrostatic deflector 164. Thus, the beam path of the primary beamlets is parallel or substantially parallel before and after the beam separation unit. In Figure 12 In the exemplarily illustrated arrangement, where the magnetic deflector 162 and the electrostatic deflector 164 act in different planes along the optical axis of the primary beamlets, the primary beamlets can be deflected. In an arrangement where the fields of the magnetic deflector and the electrostatic deflector overlap, the primary beamlets can be substantially not deflected.

[0131] The primary beamlets 103 are focused on the sample 80 by the objective lens unit 170. The signal beamlets 105 travel through the objective lens and in a direction substantially opposite to the direction of the primary beamlets 103. Thus, the Wien filter array deflects the signal beamlets 105. The deflection of the Wien filter array is based on a change of the deflection direction of the magnetic deflector 162. Thus, for the signal beamlets 105, the magnetic deflector 162 and the electrostatic deflector 164 act in the same direction.

[0132] The beam separation unit can also be regarded as an electromagnetic deflection system for separating the primary beamlets and the signal beamlets. For example, the signal beamlets can be deflected by an angle of 1° to 20°, in particular by an angle of 3° or below.

[0133] In case a rectangular array or a square array of primary beamlets is considered, the electromagnetic deflection system (e.g. the Wien filter array) can be arranged as exemplarily illustrated in Figure 13 Figure 14A and Figure 14B The electrostatic deflector 164 can be arranged by two or more elongated deflection electrodes. For example, the deflection electrodes can be parallel to the paper plane of Figure 13 The deflection electrodes can be arranged on opposite sides of the array of primary beamlets. Further deflection electrodes can be arranged between the rows of primary beamlets. For example, an array of primary beamlets with M (M >= 1) rows of primary beamlets can be arranged with M+1 electrodes. The electrodes are elongated to deflect a row of primary beamlets.

[0134] ​The magnetic deflector 162 can be provided by an array of coils. Coils 464 can be provided on a core 462. The coils 464 can be provided along a straight line and can be elongated along a direction perpendicular to the straight line. The coils can be elongated to deflect a row of primary beamlets. According to some embodiments of the present disclosure, a row of primary beamlets of the array of primary beamlets can pass between two adjacent coils of the array of coils. An array of primary beamlets having N (N >= 1) rows of primary beamlets can be provided with N+1 coils. For example, the coils can be wound on a magnetic core having a magnetic material, for example, for forming a magnetic circuit to enclose a magnetic flux line.

[0135] Figure 15 Further embodiments of the beam separation unit 160 are illustrated. The beam separation unit can be provided by a magnetic field 163. For example, the magnetic field 163 can be provided by an array of coils 464 as illustrated in Figure 14A and Figure 14B . The collimator 130 can be operated to direct the primary beamlets 103 at an angle with respect to the optical axis of the objective unit. The beam separation unit can deflect the primary beamlets parallel or substantially parallel to the optical axis of the objective unit 170. The signal beamlets directed upwards in the charged particle beam device are separated from the primary beamlets by the magnetic field 163 of the beam separation unit 160.

[0136] A beam separation unit 160 according to further embodiments is illustrated in Figures 16A to 16C . For example, three layers of magnetic material are provided. The magnetic material can be a material of high magnetic permeability and the layers can form a magnetic circuit. As illustrated in Figure 16A , a first electrostatic deflector 164 is provided. A magnetic deflector 162 is provided. A second electrostatic deflector 164 is provided. The magnetic deflector 162 can be provided between the first electrostatic deflector and the second electrostatic deflector. Embodiments of the present disclosure involving a magnetic deflector or an electrostatic deflector can also be referred to as a magnetic deflector array or an electrostatic deflector array, respectively. The magnetic deflector 162 and the one or more electrostatic deflectors 164 are configured to deflect an array of primary beamlets and / or signal beamlets. For example, the array can be formed as a one-dimensional array of electrodes as described herein.

[0137] The first electrostatic deflector 164 and the second electrostatic deflector 164 comprise at least two electrodes between the rows of the array of primary beamlets. The at least two electrodes can be a first electrode 165 and a second electrode 166. The first electrode 165 can be at a positive electrical potential and the second electrode 166 can be at a negative electrical potential or vice versa. The at least two electrodes provide an electrostatic deflection field for the rows of the array of beamlets. According to some embodiments of the present disclosure, which can be combined with other embodiments described herein, the at least two electrodes can be split electrodes or strip electrodes. Further, additionally or alternatively, at least two electrodes can be provided between the rows of the array of primary beamlets.

[0138] The magnetic deflector 162 (or magnetic deflector array) comprises one electrode (e.g. an elongated electrode or a strip electrode) between the rows of the primary beamlet array. One electrode of the magnetic deflector is surrounded by a coil. The coil can have insulated wire, for example. The one electrode can also be referred to or can provide a core for generating a magnetic field.

[0139] Embodiments of the present disclosure relate to a primary beamlet array and a signal beamlet array, respectively. The present disclosure relates to rows (and not rows and columns), irrespective of whether the rows are arranged in the x-direction or the y-direction. It is to be understood that the rows of the array can extend in a first direction and, in addition, the rows can extend in a second direction perpendicular to the first direction. From the properties of electro-optical components, it will be understood by the skilled person that the orientation of the term "row" when used herein to describe an array of primary beamlets and / or secondary beamlets.

[0140] By providing three layers of electrodes, a magnetic circuit is formed. In addition, a symmetrical arrangement is provided along the direction of the optical axis of the beamlets.

[0141] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with an array of primary beamlets is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of a sample and an objective lens unit having three or more electrodes each having an opening for the four or more primary beamlets. The openings are spaced apart by an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some embodiments, the objective lens unit can be further configured to focus the four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. The charged particle beam device can comprise a detection unit having a detection surface. One or more detection surfaces are arranged between the beam paths of the four or more primary beamlets. For example, the detection surface can convert the signal beamlets in photons and four or more photon detectors are provided for the detection unit. The beam separation unit can comprise a first electrostatic deflector, a second electrostatic deflector, and a magnetic deflector arranged between the first electrostatic deflector and the second electrostatic deflector, wherein the first electrostatic deflector, the second electrostatic deflector, and the magnetic deflector optionally form a magnetic circuit. As a further optional additional or alternative feature, the first electrostatic deflector and the second electrostatic deflector each comprise at least two elongated electrodes between the respective rows of the four or more primary beamlets. Thus, a symmetrical beam separation unit can be provided.

[0142] Now returning Figure 12 to the array of primary beamlets 103, the array can have a distance d. The pitch can be 200 pm and above (in particular 400 pm or above). At least a first pitch between the primary beamlets can be provided along a first direction (e.g. x-direction). The electrodes of the electrostatic deflector 164 and / or the core or electrodes of the magnetic deflector 162 can have a pitch similar to the first pitch. For example, the pitch of the electrodes can be within ±10% of the first pitch. Further, according to some embodiments, which can be combined with other embodiments described herein, a distance of 10% to 90% of the first pitch between the primary beamlets can be utilized to provide the beam separation between the primary beamlets and the signal beamlets (in particular in the plane of the signal detection of the signal beamlets).

[0143] As described above, the charged particle beam device 100 comprises a beam separation unit 160. The beam separation unit 160 separates the primary beamlets 103 (i.e. the primary charged particle beamlets) from the signal beamlets 105 (illustrated in Fig. 1). For example, according to some embodiments, the beam separation unit can comprise at least one magnetic deflector, a Wien filter, or any other electro-optical component, wherein the electrons are guided away from the primary charged particle beamlets, for example due to the velocity dependent Lorentz force. Figure 12

[0144] The beam separation unit can be arranged between the objective lens unit 170 and the detection unit 150. The detection unit 150 comprises a plurality of detectors or detection surfaces 152. The detection unit can comprise a plurality of conversion units 153 for converting the signal beamlets into photons. In particular, the conversion units 153 can be electro-optical conversion units. The conversion units 153 can comprise the detection surfaces 152 and in particular an array of fluorescent stripes. The array of fluorescent stripes can be arranged in the plane of the conversion units 153 and next to the primary beamlets or a row of primary beamlets. For example, the pitch of the array of fluorescent stripes can be similar to the distance d or the first pitch of the primary beamlets. The primary beamlets 103 can pass through the fluorescent stripes or the array of fluorescent stripes of the conversion units, respectively. According to some embodiments, which can be combined with other embodiments described herein, the pitch (i.e. the distance d) of the primary beamlets 103 in the plane 157 of the detection surfaces 152, the pitch of the fluorescent stripes, and the pitch of the signal beamlets 105 can be the same or substantially the same. As described above, the pitch of the primary beamlets 103 can be smaller than the pitch of the signal beamlets 105. For example, the pitch of the primary beamlets 103 can be smaller than the pitch of the signal beamlets 105 by a factor of 2 or more. For example, the pitch of the primary beamlets 103 can be smaller than the pitch of the signal beamlets 105 by a factor of 10 or more. For example, the pitch of the primary beamlets 103 can be smaller than the pitch of the signal beamlets 105 by a factor of 100 or more. For example, the pitch of the primary beamlets 103 can be smaller than the pitch of the signal beamlets 105 by a factor of 1000 or more. Figure 12 Illustratively, the signal beamlets are deflected by the beam separation unit to travel at an angle with respect to the optical axis of the objective lens unit in order to project the signal electrons onto the fluorescent stripes or the detection surfaces 152 of the electro-optical conversion units 81.

[0145] According to some embodiments, which can be combined with other embodiments described herein, at least one fluorescent stripe of the array of fluorescent stripes is arranged between two adjacent rows of primary beamlets.

[0146] According to some embodiments described herein, the detection surfaces are arranged for projecting the signal beamlets (i.e. the signal electrons) to a side next to the primary charged particle beamlets. Thus, an overlap of the spots of the signal electrons from adjacent primary charged particle beamlets can be reduced or prevented, which makes it easier to detect and distinguish the signal beamlets generated by adjacent primary beamlets. Thus, the detection and evaluation of the signal beamlets from the surface of the sample can be faster, which increases the throughput of the examination of the sample.

[0147] In Figure 12 ​In the illustrated example, the conversion unit (e.g. electro-optical conversion unit) is arranged in a series of parallel arranged fluorescent strips extending substantially in the Y direction. According to a still further embodiment, the electro-optical conversion unit or the detection surface can be provided at a plate having through-holes for the primary charged particle beamlets. The plate can extend in the XY direction. The detection surface or the fluorescent portion can be provided at the plate or the plate can comprise a fluorescent material. The fluorescent material on parts of such a plate or portions of the plate extending between the through-holes in the X or Y direction are also considered as fluorescent strips according to the present disclosure.

[0148] At the conversion unit 153, photons are generated upon incidence of the signal beamlets. The photons can be generated by the fluorescent strips or fluorescent portions. At least a portion of the photons are guided from the conversion unit to the photon detector. The photons can be guided by, for example, optical fibers 156. A first end of the optical fiber can be arranged adjacent to, coupled to, or attached to the conversion unit. The light (i.e. photons) is coupled into the optical fiber. A second end of the optical fiber can be provided at the photodetector. The optical fibers can be provided in an array corresponding to the array of signal beamlets. An array of optical fibers can be provided between rows of the primary beamlet array. For example, the array of optical fibers can be provided in one of the x-direction and the y-direction between the primary beamlet array.

[0149] According to some embodiments, which can be combined with other embodiments described herein, an array of fluorescent strips is provided, wherein each fluorescent strip is located adjacent to a primary beamlet. For example, the fluorescent strips can be located in the plane 157 of the detection surface 152 at a distance equal to the pitch of the primary beamlets. An array of optical fibers or glass fibers is provided for transmitting the generated light to a photodetector (e.g. an array of photodetectors).

[0150] According to some embodiments, which can be combined with other embodiments described herein, the detection surface 152 (i.e. the surface of the conversion unit 153) on which the signal particles impinge can comprise an electrically conductive material. For example, the electrically conductive material can be coated on the detection surface. The electrically conductive material allows to remove the electric charge generated on the detection surface.

[0151] Figure 12 Figure illustrates the beam separation and detection in the XZ plane, Figure 17 Figure illustrates the corresponding arrangement in the YZ plane. It can be seen that the optical fibers 156 can be provided to guide the photons from the conversion unit to the photodetector array 159. The optical fibers can be provided between rows of the primary beamlet array.

[0152] Photodetector arrays (such as multisensor detector systems) can be arranged at positions spaced apart from the primary sub-beam array (e.g., in a direction perpendicular to the optical axis of the primary sub-beams). Detection units may include an array of fluorescent strips, with each strip located adjacent to a primary sub-beam or a row of primary sub-beams. For example, the fluorescent strips may be located within a distance equal to the pitch of the primary sub-beams in the plane of the detection surface. According to some embodiments, the fluorescent strips may be arranged close to the primary charged particle sub-beams. Preferably, at least one strip in the array of fluorescent strips is arranged between two adjacent primary sub-beams. By arranging the fluorescent strips close to the primary sub-beams or even between two adjacent primary sub-beams, the width of the multi-beam charged particle columns can be reduced. This makes it easier to arrange multiple multi-beam charged particle columns close to each other and allows for the arrangement of more multi-beam charged particle columns in a region above the sample. Therefore, the surface of the sample can be examined more quickly, increasing the throughput of sample examination.

[0153] According to some embodiments that can be combined with other embodiments described herein, the photodetector array may include multiple photodetectors, particularly at least one photodetector for each signal sub-bundle or optical fiber. For example, the photodetector may be a photodiode or another electro-optical element including a pn junction. Additionally or alternatively, the photodetector may include a photomultiplier. Electrical signals are generated by the photodetectors. Specifically, the array of photodetectors allows for the generation of electrical signals for each signal sub-bundle.

[0154] Figure 18 The illustration shows a schematic top view of the conversion unit 153 (e.g., an electro-optical converter unit) in plan view. Figure 17 As shown, the primary sub-bundles 103 are arranged in multiple rows, where each row is in the first direction (in Figure 17 The middle section extends in the Y direction. Each row of the primary sub-bundle 103 extends in the second direction (in the Y direction). Figure 18 The fluorescent strips of the conversion unit 153 are arranged adjacent to each other (in the X direction). The fluorescent strips of the conversion unit 153 are arranged close to a row of primary sub-bundles and, for example, have a distance equal to the pitch of each row of primary sub-bundles at the conversion unit 153 or the detection surface. The openings or gaps between the fluorescent strips are arranged to allow the primary sub-bundles to pass through the plane of the detection surface.

[0155] The signal sub-beam 105 generated when the primary sub-beam impacts the sample is separated by a beam splitting unit (e.g., in...). Figure 18 The signal sub-beam is deflected in the x-direction. The signal sub-beam strikes the detection surface (i.e., the fluorescent stripe or portion of the conversion unit). The detection surface is on the side facing the beam separation unit. The conversion unit uses fluorescent material to convert the signal sub-beam into photons (light). On the side opposite the detection surface, an optical fiber 156 can be positioned to collect the generated photons or at least a portion of the generated photons.

[0156] An optical fiber 156, arranged to collect photons from individual spots of a signal sub-bundle on a specific fluorescent strip, is positioned above the fluorescent strip, particularly... Figure 17 In the ZY plane. For example... Figure 17 The schematic diagram shows that the optical fiber 156 is bent or folded in the YZ plane so that the second end of the optical fiber is positioned at the photodetector array 159.

[0157] As Figure 18 and Figure 19 An alternative to the bent or folded optical fiber 156 shown is that the optical fiber 156' is tapered at the detection surface 152. The first end of the optical fiber 156' can be cut at an angle α between 10° and 60° relative to the central axis CA of the optical fiber. At the tapered end, a fluorescent plate or fluorescent layer is arranged as the detection surface 152. Secondary electrons 105' projected onto the detection surface are converted into photons 20. At least a portion of the generated photons 20 are coupled to the first end of the optical fiber and transmitted or guided toward the photodetector through the optical fiber. Due to total internal reflection at the side surfaces of the optical fiber, the photons 20 are confined within the optical fiber. Objective lens unit and scanning (internal: block 270) One of the optical fibers in the fiber is indicated by a light-reflecting layer that can be used to at least partially coat the optical fiber 156'.

[0158] Figure 20A

[0159] Figures 20A to 20D The diagram shows objective lens unit 170. Relative to... Figure 20A This describes various aspects, details, features, and modifications of the objective lens unit. Corresponding embodiments can be combined with other embodiments described herein (particularly embodiments described herein for various parts of the charged particle beam column).

[0160] The objective lens unit includes three or more electrodes with apertures 272. The apertures 272 form an array of apertures. One aperture or opening is provided for each of the individual primary sub-beams and / or each sub-beam. Therefore, the array of apertures corresponds to the primary sub-beam array. Figure 20B As shown, an optical axis OA is set for each of the primary sub-beams. Three or more electrodes form an electrostatic lens assembly.

[0161] According to embodiments of this disclosure, an insulating plate 174 is disposed between two of three or more electrodes. According to some embodiments that can be combined with other embodiments described herein, the insulating plate 174 includes an opening for allowing two or more primary sub-beams to pass through said opening of the insulating plate 174, particularly allowing all primary sub-beams to pass through said opening of the insulating plate 174. The three or more electrodes are biased to different potentials to form a lens field for the primary sub-beams. Specifically, according to some embodiments that can be combined with other embodiments described herein, the electrodes are configured to generate a deceleration field for slowing down the primary sub-beams traveling toward the sample. For example, the deceleration field between the penultimate electrode and the last electrode can be at least 5 kV / mm.

[0162] like Figure 20A As shown, according to some embodiments that can be combined with other embodiments described herein, one or more of three or more electrodes may be electrode 172. Electrode 172 includes apertures 272 or openings, particularly an array of apertures. Electrode 172 is configured to provide a common potential around each of the apertures 272. Electrode 172 provides a common potential for the primary sub-beam array. Figure 20C As shown, electrode 172 can be connected to power supply 173 or controller. Each electrode in the series is biased to a potential. Specifically, adjacent electrodes 172 (adjacent along the optical axis) can be biased to different potentials to generate a lens field.

[0163] like Figure 20C As shown, with some modifications, one or more of the three or more electrodes may be electrode 176. Electrode 176 includes a hole 272 or an opening, particularly a region of the hole. As indicated by conductive portion 276, the hole 272 may include individual conductive portions, each of which may be set with a different potential. Electrode 176 is connected to a power supply 177 or a controller. The power supply or controller can control the potential of each of the individual conductive portions. The ability to provide different potentials for different openings allows for fine adjustment of the lens field for the respective primary sub-bundles (e.g., individually for each primary sub-bundle). Figure 20D The diagram illustrates the conductive portion 276 for each of the openings 272. According to a further embodiment, which can be combined with other embodiments described herein, some of the openings may have a common conductive portion 276, such that some of the openings can be biased to the same potential. Furthermore, at least two distinct conductive portions are provided. A first conductive portion of the first opening 272 can be biased at least to a first potential, and a second conductive portion of the second opening can be biased at least to a second potential different from the first potential.

[0164] Figure 20DFurther modifications of electrodes that can be combined with other embodiments described herein are illustrated. The electrodes of objective lens unit 170 can include four or more (e.g., eight) deflection electrodes 178. Deflection electrodes 178 can be controlled to produce a deflection field for each of the primary beamlets in the XY plane. In addition, an octupole field and / or a quadrupole field can be produced for aberration correction. The electrodes with separate deflection electrodes can be connected to a power supply 179 or a controller. For example, each of the deflection electrodes can be connected by an insulated wire to allow for separate biasing of the deflection electrodes. According to some embodiments, the electrodes with deflection electrodes can be fabricated as microelectromechanical systems (MEMS). MEMS technology deflectors allow for higher multipole density and simplify the wiring of the electrodes.

[0165] According to some embodiments, which can be combined with other embodiments described herein, the objective lens unit can include three or more electrodes (e.g., 3 to 10 electrodes) with an array of holes 272. As described above, an insulating plate 174 can be provided between adjacent electrodes. One of the electrodes can be provided with a deflection electrode 178 relative to the other electrodes. The deflection electrode 178 can be provided with a deflection field of at least 5 kV / mm. Figure 20A The deflection electrode 178 described. Figure 2 The example shown includes a first electrode 172, a second electrode 172, a third electrode 172, a first separate focusing electrode 176 with a conductive portion 276, an electrode with a deflection electrode 178, and a fourth electrode 172. For example, a deceleration field can be provided between the electrode with a deflection electrode and the fourth electrode 172. The deflection field can be at least 5 kV / mm.

[0166] According to some embodiments, a charged particle beam device for irradiating or inspecting a sample with a primary beamlet array is provided. The charged particle beam device comprises a charged particle beam source for generating a primary charged particle beam and a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam. Two or more electrodes (e.g. each electrode having one opening) with one opening for the primary charged particle beam or the four or more primary beamlets are provided, which can be biased with the multi-aperture lens plate to provide a focusing effect. The charged particle beam device further comprises a collimator for deflecting a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further comprises a scanning deflector assembly for scanning the four or more primary beamlets over a surface of a sample and an objective lens unit having three or more electrodes each having an opening for the four or more primary beamlets. The openings are spaced apart with an opening distance, wherein the objective lens unit is configured to focus the four or more primary beamlets on the sample. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets on a detection surface. The charged particle beam device further comprises a stage for supporting the sample. At least one of the three or more electrodes of the objective lens unit comprises four or more deflection electrodes for each primary beamlet, in particular eight or more deflection electrodes for each primary beamlet, each electrode having one opening for each primary beamlet, and the stage for supporting the sample. Thus, the beam position of the individual primary beamlets can be adjusted on the sample.

[0167] According to embodiments described herein, the primary charged particle beamlets are focused by the objective lens unit 170 on separate positions on the sample 80 for inspecting the sample at the separate positions simultaneously. The objective lens unit 170 can be configured for focusing the primary charged particle beamlets onto the sample, wherein the objective lens is a retardation field lens. For example, the retardation field lens can decelerate the primary charged particle beamlets to a defined landing energy. In some embodiments, the energy reduction from the column energy to the landing energy on the sample is at least a factor of 10, for example, at least a factor of 30. In one example, the landing energy is typically between about 100 eV to 8 keV, more typically 2 keV or less, for example, 1 keV or less, such as 500 eV or even 100 eV.

[0168] As Stage (internal: block 280)Exemplarily, a scan deflector assembly 271 can be provided adjacent to or within the objective lens unit 170. The scan deflector assembly 271 can provide a scan field for the primary beamlet array. For example, the scan field can be provided individually for the beamlets. For example, the scan deflector assembly 271 can be a magnetic scan deflector assembly. According to a further modification, additionally or alternatively, an electrostatic scan deflector assembly can be provided. According to some embodiments, the scan deflector assembly can be arranged between the objective lens unit 170 and the beam separation unit 160. Additionally or alternatively, the scan deflector assembly can be arranged between two of the two or more electrodes of the objective lens unit 170.

[0169] Figure 21

[0170] Figure 20A A stage 180 is illustrated which can be provided in the charged particle beam device 100 according to embodiments of the disclosure. The stage 180 comprises a motion assembly 182. The motion assembly 182 comprises a drive to move the sample 80 at least in an x-direction, a y-direction and a z-direction. Thus, the sample 80 can be moved relative to the optical axis of the objective lens unit 170 and can be adapted to the distance between the sample 80 and the objective lens unit 170. The stage 180 comprises an insulating layer 184 and a conductive layer 186. The conductive layer 186 provides a sample receiving surface. The conductive layer is arranged between the sample 80 and the insulating layer 184. As Figure 22 illustrated, the conductive layer 186 can be connected to a power supply 288. Thus, the wafer can be biased.

[0171] According to some embodiments, the insulating layer 184 insulates the sample or wafer from ground. Thus, the sample can be arranged at a potential (e.g. a high potential of at least 5 kV). Biasing the sample allows to provide voltages between components of the charged particle beam device which is beneficial for electro-optical purposes while reducing the voltage in certain areas of the charged particle beam device. For example, the emitter 111 and the sample 80 can be biased to a negative voltage. Thus, other components between the emitter and the sample can be biased to a reduced (positive) voltage. Thus, in addition to the lower voltages for deflection, aberration correction, focusing, etc. the two or more electrodes, ALA, collimator, objective lens unit, etc. do not need to be high voltage as well.

[0172] Reference is made to Figure 3AThe flowchart shown describes an embodiment of a method of inspecting a sample with four or more primary sub-beams. At operation 1221, a primary charged particle beam is generated with a charged particle source and four or more primary sub-beams are generated with a multi-aperture lens plate and two or more electrodes. Thus, an array of primary sub-beams can be provided. In operation 1222, a first primary sub-beam, a second primary sub-beam, a third primary sub-beam, and a fourth primary sub-beam of the four or more primary sub-beams are deflected relative to each other with a collimator. For example, the primary sub-beams can be deflected to be parallel. At operation 1223, the four or more primary sub-beams are scanned over a surface of a sample with a scanning deflector assembly and the four or more primary sub-beams are focused onto the sample with an objective lens unit to generate four or more signal sub-beams. At operation 1224, the four or more signal sub-beams are focused onto a detection surface with a detection distance, wherein one or more detection surfaces are arranged between respective primary sub-beams of the four or more primary sub-beams. In particular, the detection distance can be similar to an opening distance of the openings of the electrodes of the objective lens unit. At operation 1225, the four or more signal sub-beams are separated from the four or more primary sub-beams with a beam separation unit to guide the four or more signal sub-beams to the detection surface at the detection distance. According to embodiments of the present disclosure, the sub-beam distance can be 200 pm and above, in particular 400 pm or above. Thus, the openings in the objective lens unit can be 200 pm and above, in particular 400 pm or above. According to embodiments of the present disclosure, the detection distance can be 200 pm and above, in particular 400 pm or above. Thus, a pitch between the detection surfaces can be provided with the detection distance and / or the signal sub-beams impinge onto the detection surfaces with the detection distance. According to some embodiments, which can be combined with other embodiments described herein, the detection distance corresponds to a pitch between the primary sub-beams, in particular in a plane of the detection unit. Further, according to additional or alternative modifications, a spot size of the four or more signal sub-beams can be adjusted in the detection surface, in particular wherein the detection distance is larger than the spot size of the four or more signal sub-beams on the detection surface.

[0173] Some embodiments of the present disclosure provide a sub-beam distance or opening distance at which the openings of the electrodes of the objective lens unit are spaced apart by 200 pm and above, in particular 400 pm or above. Thus, the openings can have a size of, for example, 100 pm and above, in particular 200 pm or above. Thus, the number of signal electrons guided and / or focused onto the detection surface provides an improved detection efficiency. For example, the detection distance, i.e. the distance of the detection surface, can be similar to the opening distance. Further, the electrodes of the objective lens unit can focus the signal sub-beams onto the detection surface. Thus, the size of the openings in the electrodes of the objective lens unit in combination with the corresponding opening distance and, optionally, the focusing of the signal sub-beams provides an advantageous collection efficiency.

[0174] According to some embodiments, which can be combined with other embodiments described herein, in an objective lens unit having four or more deflection electrodes for each primary beamlet, the primary beamlets can be deflected and / or the stigmation can be corrected. Additionally or alternatively, the sample on a platform for supporting the sample can be biased, wherein the platform has an insulating layer.

[0175] According to some embodiments, the energy within the charged particle beam device varies depending on the position in the charged particle beam device. Examples are given below. For example, the energy of the primary charged particle beam after the beam emitter and before the multi-aperture lens plate can be about 15 kV, and is decelerated to about 3 kV in front of the array (e.g., in the array of the multi-aperture lens plate). The energy in the column of the charged particle beam device after the multi-aperture lens plate and before the collimator can be about 3 kV. In some embodiments, the collimator can accelerate the primary charged particle beamlets to an energy of about 15 kV. The landing energy of the primary charged particle beamlets (decelerated by the objective lens) can be below 1 keV (e.g., about 300 eV). Figure 3B and Figure 23 In the configuration of the exemplary illustration, in which two or more electrodes 124 are used in a deceleration mode in front of the multi-aperture lens plate 122. The energy in the column of the charged particle beam device after the multi-aperture lens plate and before the collimator can be about 3 kV. In some embodiments, the collimator can accelerate the primary charged particle beamlets to an energy of about 15 kV. The landing energy of the primary charged particle beamlets (decelerated by the objective lens) can be below 1 keV (e.g., about 300 eV).

[0176] Further, the charged particle beam device according to embodiments described herein and the method of inspecting a sample with the charged particle beam device provide for a small spot size of the primary charged particle beamlets on the sample. The spot size can be understood as the diameter of the area on the sample irradiated by a single primary charged particle beamlet. For example, the spot size of a single primary charged particle beamlet of the array of primary charged particle beamlets according to embodiments described herein can typically be less than 20 nm, more typically less than 10 nm, even more typically less than 5 nm. According to some embodiments, due to the generation of the array of primary charged particle beamlets with the beam source according to embodiments described herein, the single primary charged particle beamlets can have a high current density. The high current density helps to increase the signal-to-noise ratio and thus the throughput of the charged particle beam device.

[0177] As described above, the charged particle beam device according to embodiments described herein allows to provide a primary charged particle beamlet array. According to some embodiments, the primary charged particle beamlet array can typically comprise three or more primary charged particle beamlets per column, more typically ten or more primary charged particle beamlets per column. According to some embodiments described herein, the charged particle beam device and the method for inspecting a sample with the charged particle beam device according to embodiments described herein provide a primary charged particle beamlet array within one column of the charged particle beam device at the sample surface having a distance to each other. For example, the distance between two primary charged particle beamlets within one column, i.e. adjacent charged particle beamlets in the direction of the rows, can typically be 0.2 mm or above and / or 3 mm or below.

[0178] In some embodiments, two or more charged particle beam devices according to embodiments described herein can be arranged in an array in a multi-column multi-beam microscope (MCM). The plurality of columns each having a primary charged particle beamlet array for inspecting a sample can further increase the processing speed and throughput.

[0179] Figure 23 A charged particle beam device assembly is illustrated, wherein three charged particle beam devices 100 according to embodiments of the present disclosure are arranged in an array. According to some embodiments, one or more charged particle beam devices can be arranged in an array, such as a one-dimensional array or a two-dimensional array. The charged particle beam devices according to embodiments of the present disclosure each comprise a charged particle beam source 110, two or more electrodes, i.e. electrodes having openings for primary charged particle beams or openings common to primary charged particle beamlets, an aperture lens array, a collimator 130, an optional detection unit 150, an optional beam separation unit 160, and an objective lens unit 170, and comprise various modifications described in the present disclosure additionally or alternatively with respect to each other.

[0180] As ​ illustrated, the charged particle beam device comprises a plurality of columns each having a plurality of beamlets within the column. The plurality of columns is arranged above a sample stage having a sample 80. Thus, the multi-column multi-beam device can be configured for inspecting a sample, a specimen or a wafer, in particular a single sample.

[0181] Embodiments of the present disclosure provide a number of advantages, some of which are described as follows: EBI throughput can be increased, particularly given improved collection efficiency of signal electrons; aberrations for primary beamlets at the periphery of the primary beamlet array can be reduced, particularly octupole aberrations that are reduced; total beam current of the primary beamlets on the sample can be increased, which increases the signal-to-noise ratio of the imaging; aberrations for the primary beamlets can be reduced, particularly hexapole aberrations; contamination can be removed, particularly for the beam limiting apertures of the multi-aperture lens plate, and thus maintenance requirements can be reduced; the pitch of the primary beamlets of the primary beamlet array can be adjusted at the collimator; beam adjustment of the primary beamlets can be measured at the collimator; and the beam position of individual primary beamlets can be adjusted on the sample with the objective lens unit. Furthermore, the separation of the primary beamlets from the multi-aperture plate until impinging on the sample reduces crosstalk.

[0182] While the foregoing is directed to embodiments, other and further embodiments can be devised without departing from the basic scope of the disclosure, and the scope of the disclosure is determined by the claims that follow.

Claims

1. A charged particle beam device for irradiating or inspecting a sample with an array of primary beamlets, the charged particle beam device comprising: a charged particle beam source for generating a primary charged particle beam; a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam; two or more electrodes having one opening for the primary charged particle beam or the four or more primary beamlets, the two or more electrodes being biasable with the multi-aperture lens plate to provide a focusing effect; a collimator for deflecting a first, a second, a third, and a fourth primary beamlet of the four or more primary beamlets relative to each other; an alignment system disposed between the multi-aperture lens plate and the collimator, wherein the alignment system comprises at least one quadrupole to adapt a pitch between the four or more primary beamlets; a detection unit having a detection surface, one or more detection surfaces arranged between beam paths of the four or more primary beamlets; a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample; an objective lens unit having three or more electrodes each having an opening for the four or more primary beamlets, the openings being spaced apart by an opening distance, the objective lens unit being configured to focus the four or more primary beamlets on the sample to generate four or more signal beamlets and to direct the four or more signal beamlets onto the detection surface; and a stage for supporting the sample.

2. The charged particle beam device of claim 1, wherein the opening distance is 200 pm or more.

3. The charged particle beam device of claim 1, wherein the objective lens unit comprises four or more electrodes to adjust a spot size of the four or more signal beamlets on the detection surface.

4. The charged particle beam device of claim 3, wherein the spot size of the four or more signal beamlets is adapted to a detection distance.

5. The charged particle beam device of any of claims 1 to 4, further comprising a beam separation unit for separating the four or more primary beamlets from the four or more signal beamlets, wherein the beam separation unit comprises: a first electrostatic deflector; a second electrostatic deflector; and a magnetic deflector disposed between the first electrostatic deflector and the second electrostatic deflector.

6. The charged particle beam device of claim 5, wherein the first electrostatic deflector, the second electrostatic deflector, and the magnetic deflector form a magnetic circuit.

7. The charged particle beam device of claim 5, wherein the first electrostatic deflector and the second electrostatic deflector each comprise at least two elongated electrodes between rows of the four or more primary beamlets. ​ 8. The charged particle beam device of any of claims 1 to 4, wherein the plurality of apertures of the multi-aperture lens plate forms an aperture array, and wherein a number of apertures in the aperture array is greater than a number of primary beamlets impinging on the sample.

9. The charged particle beam device of any of claims 1 to 4, wherein the plurality of apertures of the multi-aperture lens plate has a square shape or a substantially square shape, wherein the substantially square shape is a square shape with rounded corners.

10. The charged particle beam device of any of claims 1 to 4, further comprising: a heater for heating the multi-aperture lens plate.

11. The charged particle beam device of claim 1, further comprising: one or more aperture arrays between the multi-aperture lens plate and the objective lens unit, each of the one or more aperture arrays having a plurality of apertures for the four or more primary beamlets.

12. The charged particle beam device of claim 11, wherein the collimator is disposed between a first aperture array of the one or more aperture arrays and a second aperture array of the one or more aperture arrays.

13. The charged particle beam device of claim 11, further comprising: a current meter attached to one or more electrically conductive surfaces on at least one aperture array of the one or more aperture arrays.

14. The charged particle beam device of claim 13, wherein the alignment system is disposed between the multi-aperture lens plate and the at least one aperture array.

15. The charged particle beam device of claim 11, further comprising: an aperture array holder corresponding to at least one of the one or more aperture arrays, the aperture array holder separating a vacuum compartment of the charged particle beam device into a plurality of vacuum compartments separated from each other.

16. The charged particle beam device of any of claims 1 to 4, wherein the collimator comprises: two or more first elongated electrodes for deflecting a row of the four or more primary beamlets along a first direction, and two or more second elongated electrodes for deflecting a row of the four or more primary beamlets along a second direction, the second direction being different from the first direction.

17. The charged particle beam device of any of claims 1 to 4, wherein the collimator is configured to deflect the first primary beamlet, the second primary beamlet, the third primary beamlet, and the fourth primary beamlet of the four or more primary beamlets to emerge from the collimator in parallel with respect to each other.

18. The charged particle beam device of any of claims 1 to 4, wherein the objective lens unit comprises: one or more insulator plates disposed between two electrodes of the three or more electrodes, the one or more insulator plates having an opening for the four or more primary beamlets to pass through the one opening of the insulator plates.

19. The charged particle beam device of claim 18, wherein the one or more insulating plates are configured to allow a deceleration field for decelerating the primary beamlets traveling towards the sample, the deceleration field between the second last electrode and the last electrode is at least 5 kV / mm.

20. The charged particle beam device of any of claims 1 to 4, wherein at least one of the three or more electrodes of the objective lens unit comprises four or more deflection electrodes for each primary beamlet.

21. The charged particle beam device of claim 20, wherein each of the four or more deflection electrodes is connected by an insulating wire to allow individual biasing of the deflection electrodes.

22. The charged particle beam device of claim 21, wherein the insulating wire is connected to a connector at one side of an array formed by the four or more primary beamlets.

23. The charged particle beam device of any of claims 1 to 4, wherein the stage for supporting the sample comprises: an insulating layer configured to allow biasing of the sample.

24. A charged particle beam device assembly comprising: a first charged particle beam device according to any of claims 1 to 4; and a second charged particle beam device for irradiating or inspecting the sample with an array of primary beamlets, the second charged particle beam device comprising: a charged particle beam source for generating a primary charged particle beam; a multi-aperture lens plate having a plurality of apertures for forming four or more primary beamlets from the primary charged particle beam; two or more electrodes having one opening for the primary charged particle beam or the four or more primary beamlets, the two or more electrodes being biasable with the multi-aperture lens plate to provide a focusing effect; a collimator for deflecting a first, a second, a third, and a fourth primary beamlet of the four or more primary beamlets relative to each other; a detection unit having a detection surface, one or more detection surfaces being arranged between beam paths of the four or more primary beamlets; a scanning deflector assembly for scanning the four or more primary beamlets over a surface of the sample; and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more primary beamlets, the openings being spaced apart by an opening distance, the objective lens unit being configured to focus the four or more primary beamlets on the sample to generate four or more signal beamlets and to direct the four or more signal beamlets onto the detection surface.

25. The charged particle beam device assembly of claim 24, wherein the first charged particle beam device and the second charged particle beam device are arranged next to each other over the sample for simultaneously irradiating or inspecting different portions of a surface of the sample.

26. A method for inspecting a sample with four or more primary sub-beams, comprising the steps of: generating a primary charged particle beam with a charged particle beam source; generating the four or more primary sub-beams with a multi-aperture lens plate and two or more electrodes, wherein the multi-aperture lens plate has a plurality of apertures for forming the four or more primary sub-beams from the primary charged particle beam; deflecting a first, a second, a third, and a fourth primary sub-beam of the four or more primary sub-beams relative to each other with a collimator; controlling an alignment system upstream of the collimator to minimize a measured current or to maximize a signal from a signal sub-beam, wherein the alignment system comprises at least one quadrupole to adapt a pitch between the four or more primary sub-beams; scanning the four or more primary sub-beams over a surface of the sample with a scanning deflector assembly; focusing the four or more primary sub-beams on the sample with an objective lens unit, each electrode of the objective lens unit having an opening for the four or more primary sub-beams, the openings being spaced apart by an opening distance; and directing the four or more signal sub-beams onto a detection surface, wherein one or more detection surfaces are arranged between respective primary sub-beams of the four or more primary sub-beams.

27. The method of claim 26, wherein the opening distance is 200 pm or more.

28. The method of any one of claims 26 to 27, further comprising the step of: adjusting a spot size of the four or more signal sub-beams in the detection surface.

29. The method of any one of claims 26 to 27, further comprising the step of: heating the multi-aperture lens plate with a heater.

30. The method of any one of claims 26 to 27, deflecting the first, the second, the third, and the fourth primary sub-beam of the four or more primary sub-beams parallel relative to each other.

31. The method of any one of claims 26 to 27, wherein the objective lens unit comprises three or more electrodes, the method further comprising the step of: decelerating the four or more primary sub-beams between a penultimate electrode and a last electrode of the three or more electrodes with a deflection field, the deflection field being at least 5 kV / mm.

32. The method of any one of claims 26 to 27, further comprising the step of: deflecting and / or correcting the primary sub-beams in the objective lens unit with four or more deflection electrodes for each primary sub-beam.

33. The method of any one of claims 26 to 27, further comprising the step of: biasing the sample on a platform supporting the sample, the platform having an insulating layer.

34. The method of any one of claims 26-27, further comprising the step of: extracting the primary charged particle beam from the charged particle beam source with an extractor; accelerating the primary charged particle beam after the extractor; and decelerating the primary charged particle beam toward the multi-aperture lens plate with the two or more electrodes, wherein a first electrostatic field between a last electrode of the two or more electrodes upstream of the multi-aperture lens plate and the multi-aperture lens plate is less than a second electrostatic field between a penultimate electrode and the last electrode of the two or more electrodes.

35. The method of claim 34, wherein the decelerating step is provided such that a spherical and chromatic aberration coefficient of a lens formed by the multi-aperture lens plate and the two or more electrodes is minimized, and a pitch of the four or more primary sub-beams at the collimator matches a collimator pitch of the collimator.

36. The method of claim 34, wherein the decelerating step is provided such that a field curvature at the collimator is zero.

37. A method of aligning an array of four or more primary sub-beams, comprising the steps of: generating a primary charged particle beam with a charged particle source; generating the four or more primary sub-beams with a multi-aperture lens plate and two or more electrodes, wherein the multi-aperture lens plate has a plurality of apertures for forming the four or more primary sub-beams from the primary charged particle beam; deflecting a first, second, third, and fourth primary sub-beam of the four or more primary sub-beams relative to one another with a collimator; controlling an alignment system upstream of the collimator to provide at least one of: deflecting the four or more primary sub-beams with a deflection field, adapting a pitch between the four or more primary sub-beams, and rotating an array formed by the four or more primary sub-beams in a plane of an aperture array; and measuring an electrical current at one or more conductive surfaces on the aperture array.

38. The method of claim 37, wherein the alignment system is controlled to minimize the electrical current at the one or more conductive surfaces.

39. The method of claim 38, wherein the one or more conductive surfaces are disposed between openings in the aperture array.

40. The method of any one of claims 37-39, wherein the alignment system is controlled to increase a signal from a signal sub-beam.

41. The method of any one of claims 37-39, wherein the alignment system is controlled to maximize the electrical current at the one or more conductive surfaces.

42. The method of claim 38, wherein the one or more conductive surfaces are disposed outside of an array of openings formed by openings in the aperture array.

43. The method of any one of claims 37-39, wherein the control of the alignment system comprises one or more of the following control procedures: a) scanning the four or more primary beams with a deflection field in at least a first direction in the plane of the aperture array; b) scanning the four or more primary beams in a second direction perpendicular to the first direction in the plane of the aperture array; c) adapting the pitch between the four or more primary beams with a quadrupole field in at least a third direction in the plane of the aperture array; d) adapting the pitch between the four or more primary beams with a quadrupole field in at least a fourth direction in the plane of the aperture array; and e) rotating the array formed by the four or more primary beams in the plane of the aperture array.

44. The method of claim 43, wherein control procedure a) and / or b), control procedure c) and / or d), and control procedure e) are executed sequentially.

45. The method of claim 43, wherein control procedure a) and / or b), control procedure c) and / or d), and control procedure e) are executed sequentially in an iterative manner. ​

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