Method for inspecting a specimen and charged particle beam device

Abstract

To provide a charged particle beam device for irradiating or inspecting a sample.SOLUTION: The charged particle beam device includes 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. Two or more electrodes are provided having one opening, e.g. each having one opening for the primary charged particle beam or the four or more primary beamlets. The charged particle beam device further includes 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 with respect to each other. The charged particle beam device further includes 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 includes a stage for supporting the specimen.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments relate to charged particle beam devices, e.g., for inspection system applications, test system applications, defect review or critical dimensioning applications, etc. Embodiments also relate to methods of operating charged particle beam devices. More particularly, embodiments relate to charged particle beam devices that are multi-beam systems for general purpose (e.g., imaging biological structures) and / or high-throughput EBI (Electron Beam Inspection). Embodiments relate to devices and methods for inspecting the surface of a sample using a multi-beam charged particle column. [Background technology]

[0002] Current semiconductor technology relies heavily on precise control of the various processes used during the production of integrated circuits. Accordingly, wafers are repeatedly inspected to locate problems as quickly as possible. Additionally, during wafer processing, masks or reticles are also inspected before actual use to ensure that the mask accurately defines their respective patterns. Inspection of wafers or masks for defects involves examining the entire wafer or mask area, for example, for the production of 300 mm wafers. In particular, inspection of wafers during wafer manufacturing involves examining the entire wafer area within a short time frame so that production throughput is not limited by the inspection process.

[0003] Scanning electron microscopes (SEMs) have been used to inspect wafers. For example, a single, finely focused electron beam is used to scan the surface of the wafer. When the electron beam strikes the wafer, secondary and / or backscattered electrons, i.e., signal electrons, are generated and measured. Pattern defects at a certain location on the wafer are detected by comparing the intensity signal of the secondary electrons with, for example, a reference signal corresponding to the same location on the pattern. However, with the increasing demand for higher resolution, scanning the entire surface of a wafer takes a long time. Accordingly, using conventional (single-beam) scanning electron microscope (SEM) techniques for wafer inspection is difficult because this technique does not provide individual throughput.

[0004] Inspection of wafers and masks for defects in semiconductor technology requires high-resolution and fast inspection tools for both full wafer or mask application and hot spot inspection. Electron-beam inspection is becoming increasingly important because optical tools have limited resolution and cannot handle shrinking defect sizes. Especially for the 20nm node and below, the high-resolution capabilities of electron-beam-based imaging tools are required to detect all defects of interest.

[0005] In light of the above, there is provided a charged particle multi-beam device and method for inspecting a specimen with an array of beamlets of charged particles that overcomes at least some of the problems in the art. Summary of the Invention

[0006] In light of the above, a charged particle beam device, a charged particle beam device assembly, a method for inspecting a specimen with an array of charged particle beamlets, and a method for aligning an array of four or more primary beamlets are provided. Further aspects, advantages, and features will become apparent from the dependent claims, the description, and the accompanying drawings.

[0007] According to one embodiment, there is provided a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets, the charged particle beam device including: 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 aperture for the primary charged particle beam or the four or more primary beamlets, the two or more electrodes and the multi-aperture lens plate being biasable to provide a focusing action; 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 one another; and a collimator for deflecting the four or more primary beamlets into four or more signal beams. the detection unit having a detection surface, one or more detection surfaces being positioned between beam paths of the four or more first-order beamlets; a scanning deflector assembly for scanning the four or more first-order beamlets across a surface of the specimen; an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more first-order beamlets, the apertures being spaced apart by an aperture distance, the objective lens unit configured to focus the four or more first-order beamlets onto the specimen and the four or more signal beamlets onto the detection surface; and a stage for supporting the specimen.

[0008] According to one embodiment, a charged particle beam device assembly is provided, the charged particle beam device assembly including 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 specimen with an array of primary beamlets, the second charged particle beam device including: 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 aperture, e.g., two or more electrodes each having one aperture for the primary charged particle beam or the four or more primary beamlets, the two or more electrodes and the multi-aperture lens plate being biasable to provide a focusing action; 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 one another; the first-order beamlets from the four or more signal beamlets; a detection unit having a detection surface, the one or more detection surfaces being disposed between beam paths of the four or more first-order beamlets; a scanning deflector assembly for scanning the four or more first-order beamlets across a surface of the specimen; and an objective lens unit having three or more electrodes, each electrode having an opening for the four or more first-order beamlets, the openings being spaced apart by an opening distance, the objective lens unit configured to focus the four or more first-order beamlets onto the specimen and the four or more signal beamlets onto the detection surface.

[0009] According to one embodiment, a method for inspecting a specimen with four or more primary beamlets is provided. The method includes 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 one another with a collimator; scanning the four or more primary beamlets across a surface of the specimen with a scanning deflector assembly; focusing the four or more primary beamlets on the specimen to generate four or more signal beamlets with an objective lens unit, wherein each electrode of the objective lens unit has an aperture for the four or more primary beamlets, the apertures being spaced apart by an aperture distance; focusing the four or more signal beamlets onto a detection plane, wherein one or more detection planes are positioned between each of the four or more primary beamlets; and separating the four or more signal beamlets from the four or more primary beamlets with a beam separation unit and guiding the four or more signal beamlets to the detection plane.

[0010] According to one embodiment, there is provided a method for aligning an array of four or more primary beamlets, the method including: 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, a second, a third, and a fourth of the four or more primary beamlets relative to one another with a collimator, controlling an alignment system upstream of the collimator to scan the four or more primary beamlets across openings in the aperture array, and measuring current at one or more conductive surfaces on the aperture array.

[0011] The embodiments are also directed to apparatuses for implementing the disclosed methods, including apparatus parts for performing each described method feature. These method features may be performed by hardware components, by a computer programmed by appropriate software, by any combination of the two, or in any other manner. Furthermore, the embodiments are also directed to methods of operating the described apparatus. The embodiments include method features for performing all functions of the apparatus.

[0012] In order that the above-mentioned features may be understood in detail, a more particular description of what has been briefly summarized above may be had by reference to the following embodiments, the accompanying drawings of which relate to the embodiments and which are described below. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram of a charged particle beam device for specimen inspection according to embodiments described herein; [Figure 2] FIG. 1 is a schematic diagram of another charged particle beam device for specimen inspection according to embodiments described herein. [Figure 3A-3B] FIG. 10 is a schematic diagram of an aperture lens array of a multi-beam generator according to an embodiment of the present disclosure, wherein the aperture lens array is provided specifically in a deceleration mode. [Figure 4A] FIG. 1 is a schematic diagram of an aperture lens array of a multi-beam generator according to an embodiment of the present disclosure, wherein the aperture lens array is provided specifically in an acceleration mode. [Figure 4B] FIG. 1 is a schematic diagram of an aperture lens array of a multi-beam generator according to an embodiment of the present disclosure. [Figure 5A-5B] 1 is a schematic diagram of a multi-aperture lens plate (aperture lens array) according to an embodiment of the present disclosure. [Figures 6A-6B] 1 is a schematic diagram of apertures in a multi-aperture lens plate according to an embodiment of the present disclosure. [Figure 7A] 1 is a schematic diagram of a collimator and associated components such as an aperture array and / or alignment system according to an embodiment of the present disclosure. [Figure 7B-7C] FIG. 1 is a schematic diagram of an alignment system according to an embodiment of the present disclosure. [Figure 8A-8B] 1 is a schematic side view of a deflector array of a collimator according to embodiments described herein. [Figure 9] 1 is a schematic top view of a deflector array of a collimator according to an embodiment described herein. [Figure 10] 10 is a schematic side view of a deflector array of a collimator according to an embodiment described herein, such as the deflector array shown in FIG. 9. [Figure 11] 1 is a schematic diagram of a charged particle beam device according to an embodiment of the present disclosure. [Figure 12] 1 is a schematic diagram of a portion of a charged particle beam device according to an embodiment of the present disclosure, depicting a detection unit and a beam separation unit; [Figure 13] FIG. 1 is a schematic diagram of a beam separation unit according to an embodiment of the present disclosure. [Figures 14A-14B] 2A and 2B are schematic top and side views, respectively, of a magnetic deflector of a beam separator according to an embodiment of the present disclosure; [Figure 15] FIG. 1 is a schematic diagram of a beam separation unit according to an embodiment of the present disclosure. [Figures 16A-16C] FIG. 10 is a schematic diagram of a further beam separation unit according to an embodiment of the present disclosure. [Figure 17] 1 is a schematic diagram of a portion of a charged particle beam device according to an embodiment of the present disclosure, depicting a detection unit; [Figure 18] FIG. 18 is a schematic top view of the detection unit shown in FIG. 17. [Figure 19] FIG. 10 is a schematic diagram of a further detection unit according to an embodiment of the present disclosure. [Figures 20A-20D] 1 is a schematic diagram of an objective lens unit according to embodiments described herein depicting modifications to the electrodes. [Figure 21] 1 is a schematic diagram of a stage for a charged particle beam device according to embodiments described herein. [Figure 22]1 is a flow diagram illustrating a method for inspecting a specimen with multiple primary beamlets in a column of a charged particle beam device. [Figure 23] 1 is a schematic diagram of a charged particle beam device assembly combining two or more charged particle beam devices according to the present disclosure. [Figures 24A-24B] FIG. 1 is a schematic diagram of an aperture array with a conductive surface for current measurement according to embodiments described herein. [Figure 25] 1 is a flow diagram illustrating a method for aligning an array of primary beamlets according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] Reference will now be made in detail to various embodiments. One or more example embodiments are illustrated in the figures. Within the following description of the drawings, like reference numerals refer to like components. Differences with respect to individual embodiments will be discussed. Each example is provided by way of explanation and is not meant to be limiting. Furthermore, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield still further embodiments. The description is intended to cover modifications and variations.

[0015] Without limiting the scope of protection of the present application, hereinafter, a charged particle beam device or components thereof will be exemplarily referred to as a charged particle beam device, which includes a primary electron beam and detection of secondary or backscattered particles such as electrons. As described herein, discussions and explanations regarding detection are exemplarily described with respect to electrons in a scanning electron microscope. Other types of charged particles, such as positive ions, can be emitted and / or detected by devices in various different instruments. Embodiments relate, for example, to a primary beam of electrons, primary beamlets, and one or more signal beams. The primary beam, primary beamlets, and / or one or more signal beams can also be provided by other charged particles such as electrons. Furthermore, the one or more signal beams can include other signals, such as particulates, as described above.

[0016] According to embodiments herein, which can be combined with other embodiments, a signal (charged particle) beam or 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 a primary beam or primary beamlet impinging on a specimen or by a primary beam or primary beamlet backscattering from the specimen. The primary charged particle beam or primary charged particle beamlet is generated by a particle beam source and is guided and deflected onto the specimen to be inspected or imaged.

[0017] "Specimens" or "samples" as referred to herein include, but are not limited to, wafers, semiconductor wafers, semiconductor workpieces, photolithography masks, and other workpieces such as memory disks. Embodiments may be applied to any workpiece on which material is deposited or structured. According to some embodiments, which may be combined with other embodiments described herein, apparatus and methods are configured or adapted for electron beam inspection, critical dimensioning applications, and defect review applications.

[0018] An embodiment of the present disclosure provides a charged particle beam device 100, as exemplarily shown in FIG. 1 . The charged particle beam device 100 includes a multi-beam generator. The multi-beam generator may include a charged particle beam source 110, two or more electrodes, and an aperture lens array. The charged particle beam source 110 includes a particle beam emitter 111 that emits a primary charged particle beam, e.g., an electron beam. According to an embodiment 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. An aperture lens array or multi-aperture lens plate 122 generates primary particle beamlets from the primary beam. One or more electrodes and the multi-aperture lens plate can operate as electrodes of an electrostatic lens. Accordingly, one or more electrodes can be lens electrodes. In particular, one or more electrodes can include apertures for the primary beam. The multi-aperture lens plate includes apertures for generating the primary beamlets. One or more electrodes, ie, electrodes common to the beamlets and the multi-aperture lens plate, act together specifically as if those beamlets were affected by individual lenses corresponding to openings or apertures in the multi-aperture lens plate.

[0019] The beamlets generated by the aperture lens array are collimated by a collimator 130. For example, the collimator may include one of the deflector arrays and lenses shown in FIG. 1. The collimated beamlets may travel essentially parallel and / or along the optical axis of the objective lens unit 170 onto the sample or specimen 80. One or more further aperture arrays 140 may be provided. For example, an aperture array may be provided downstream of the collimator 130.

[0020] The beam separation unit 160 separates the first-order beamlets from one or more signal beamlets, e.g., signal beamlets corresponding to the first-order beamlets. The signal beamlets can be detected by the detection unit 150. As an example, several detection planes 152 are shown in FIG. 1. According to the embodiments described herein, there can be one detection plane per signal beamlet, or one detection plane per row of signal beamlets.

[0021] The objective lens unit 170 includes a plurality of electrodes having an array of holes or apertures. The plurality of electrodes can act as an electrostatic lens for beamlets passing through corresponding holes and apertures in the plurality of electrodes. The objective lens unit can be provided as a deceleration lens. The plurality of electrodes can be set to a potential that decelerates the primary beamlets before they strike the specimen.

[0022] The objective lens unit 170 specifically focuses the beamlets individually onto the specimen 80. The specimen 80 can be provided on a stage 180, e.g., a wafer holder having drivers. For example, the drivers can move the specimen or sample in the x, y, and z directions.

[0023] FIG. 2 illustrates another exemplary embodiment of a charged particle beam device 100. The dotted boxes illustrated in FIG. 2 indicate different parts of the charged particle beam device. For example, box 210 refers to the charged particle beam source 110. Box 220 refers to a combination of two or more electrodes and an aperture lens array. Box 230 refers to the collimator 130. Box 250 refers to the beam separation unit 160 and the detection unit 150. Box 270 refers to the objective lens unit 170. Box 280 refers to the stage 180. Aspects, features, details, and components are described in more detail below with reference to the respective boxes. According to embodiments of the present disclosure, the features, aspects, details, components, modifications, and variations of the more detailed descriptions can be combined with each other.

[0024] 2, it is further noted that collimator 130 can include deflector array 132 as described herein as well as lens 232 as described herein. Additionally, components associated with collimator 130 or box 230, i.e., components proximate or adjacent to the collimator, can include alignment deflector system 234, which will be described in more detail below. Additionally, charged particle beam device 100 can further include scanning deflector assembly 271, which can be associated with box 270. For example, scanning deflector assembly 271 scans the beamlets across specimen 80 and can be located within or proximate objective lens unit 170.

[0025] The multi-beam generator will now be described with reference to Figures 3A to 6C. The multi-beam generator includes a charged particle beam source 110, two or more electrodes, and an aperture lens array.

[0026] Charged particle beam source (in box 210) According to some embodiments, which can be combined with other embodiments described herein, the charged particle beam source 110 (see also box 210) can include an emitter 111. In particular, a single emitter, for example 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).

[0027] Schottky or TFE emitters currently have a maximum of 2·10 8 Am -2 (SR) -1 V -1 are available with a measured equivalent brightness of up to 5·10 9 Am -2 (SR) -1 V -1 have a measured equivalent luminance of at least 5·10 7 Am -2 (SR) -1 V -1Advantageously, the charged particle beam has a luminance of 1×10. According to embodiments of the present disclosure, a high brightness emitter is provided. Accordingly, a beneficial current can be provided for each beamlet on the specimen such that a signal-to-noise ratio is provided that allows for high throughput for each beamlet. For example, according to some embodiments that can be combined with other embodiments described herein, the emitter has a luminance of 1×10, as described above. 8 Am -2 (SR) -1 V -1 ~5×10 8 Am -2 (SR) -1 V -1 or even higher.

[0028] The charged particle beam emitters described herein can be cold field emitters (CFEs), Schottky emitters, TFEs, or another high-current, high-brightness charged particle beam source (e.g., an electron beam source). A high current is considered to be 5 μA or more at 100 mrad, e.g., up to 5 mA, e.g., 30 μA at 100 mrad to 1 mA at 100 mrad, e.g., about 300 μA at 100 mrad. According to some implementations, the current is essentially uniformly distributed, e.g., with a deviation of ±10%, particularly for linear or rectangular arrays. According to some embodiments, which can be combined with other embodiments described herein, the primary charged particle beam source or primary charged particle beamlet source can have a diameter of 2 nm to 100 nm.

[0029] According to further embodiments, which can be combined with other embodiments described herein, a TFE or another high equivalent brightness source, e.g., an electron beam source, capable of providing a large beam current is a beam source whose brightness does not decrease by more than 20% of its maximum value when the emission angle is increased to provide a maximum of 10 μA to 100 μA, e.g., 30 μA.

[0030] In some embodiments, the emitter 11 may be a single thermal field emission emitter, preferably a Schottky type emitter, to emit a diverging electron beam. The primary beam, i.e., a single primary beam from a single emitter, may be emitted towards the multi-aperture lens plate 122. To produce multiple primary beamlets, multiple apertures are arranged, one primary beamlet per aperture.

[0031] According to a further embodiment, which can be combined with other embodiments described herein, the charged particle beam source 110 can include at least one of a suppressor 312 and an extractor 314. If 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. If 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 the embodiment described herein, the suppressor can particularly control the current emitted from the emitter and the profile of the primary beam. The extractor can extract charged particles, such as electrons, from the tip of the emitter 111. Accordingly, an electrostatic field, for example for field emission, can be provided by the extractor.

[0032] 3A shows a schematic diagram of a part of a charged particle beam device comprising an emitter 111, a suppressor 312 and an extractor 314. Accordingly, a charged particle beam source 110 (see also box 210) is provided.

[0033] According to a further embodiment, which can be combined with other embodiments described herein, a first electrode 324 can be provided to act as an extractor. The first electrode 324 shown in FIG. 3B can be set to a potential that causes electrons to be emitted from the tip, particularly relative to the potential of the tip of the emitter 111. Due to the small curvature of the sharply pointed tape and the potential difference, for example, several kilovolts, a high electric field can cause field emission. In the case of a Schottky-type emitter, a high electric field promotes thermionic emission.

[0034] According to some embodiments, which can be combined with other embodiments described herein, the potential difference between the tip of the emitter 111 and the extractor, e.g., the extractor 314 shown in FIG. 3A or the electrode 324 shown in FIG. 3B, can be 5 keV or more, e.g., 10 keV or more. The extractor or a first electrode of the two or more electrodes extracts charged particles from the emitter. The charged particles are then accelerated to a high potential within the column. According to some embodiments, additional electrodes can be provided to accelerate charged particles, e.g., electrons, within the column. The charged particle energy within the column can be 8 keV or more, particularly at least 15 keV or more.

[0035] Common electrode and aperture lens array (in box 220) The multi-beam generator includes two or more electrodes and an aperture lens array. Figure 3A shows four electrodes 124 and an aperture lens array, i.e., a multi-aperture lens plate 122. According to some embodiments, which can be combined with other embodiments described herein, two to six electrodes, particularly electrostatic electrodes, and a multi-aperture lens plate can be provided. The multi-aperture lens plate includes multiple apertures. The aperture lens array (ALA) or multi-aperture plate generates one primary beamlet per aperture.

[0036] The aperture lens array is located downstream of the charged particle beam source 110, and the aperture array splits the diverging primary charged particle beam into multiple primary charged particle beamlets. In addition, lenses 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 plane 222 in FIG. 3A. Plane 222 is located downstream of the multi-aperture lens plate, i.e., multi-aperture lens plate 122 is located between plane 222 and the emitter 111.

[0037] Accordingly, the charged particle beam source and the ALA constitute a multi-beam generator for generating a plurality of primary charged particle beamlets that are directed toward the surface of the sample. The aperture lens array, i.e., the multi-aperture lens plate, interacts with two or more electrodes 124. The two or more electrodes and the aperture lens plate are biased to form an electrostatic lens field for the primary beam or to generate the primary beamlets, respectively. That is, the two or more electrodes and the aperture plate generate a plurality of virtual beam sources corresponding to the beamlets.

[0038] According to some embodiments, the multi-aperture lens plate 122 can be provided downstream of two or more electrodes 124, as shown, for example, in FIG. 3A . In other words, the two or more electrodes 124 are provided between the multi-aperture lens plate 122 and the respective charged particle beam source and / or emitter 111. The two or more electrodes operate in a deceleration mode. According to further embodiments, which can be combined with other embodiments described herein, the two or more electrodes 124 can be located downstream of the multi-aperture lens plate 122. In other words, the multi-aperture lens plate 122 can be located between the two or more electrodes 124 and the respective charged particle beam source and / or emitter. Accordingly, the two or more electrodes operate in an acceleration mode. This is shown, for example, in FIG. 4A . According to further embodiments, two or more electrodes 124 can be provided, as exemplarily shown in FIG. 4B . The multi-aperture lens plate can be provided between two of the two or more electrodes 124. According to embodiments of the present disclosure, two or more electrodes 124 can have aperture openings through which the primary charged particle beam can pass. For example, two or more electrodes can each have one aperture through which the primary charged particle beam can pass, or for electrodes located downstream of the multi-aperture lens plate, two or more electrodes can each have one aperture through which the primary beamlet can pass.

[0039] FIG. 3B illustrates a further modification of the aperture array that can be combined with other embodiments of the present disclosure. A heater is provided for the multi-aperture lens plate 122. The heater can include a power supply 322. For example, the power supply can provide current for the heater provided in the multi-aperture lens plate 122. For example, a heating element can be attached to or embedded within the multi-aperture lens plate. Heating the multi-aperture lens plate can remove contamination. The multi-aperture lens plate blocks a portion of the charged particle beam, i.e., the primary beam. Furthermore, the apertures in the multi-aperture lens plate can provide beam-limiting apertures for beamlet formation. Accordingly, contamination of the apertures can degrade beamlet formation. Accordingly, removing contamination, for example by heating, can provide an improved charged particle beam device and / or reduce maintenance requirements.

[0040] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more first-order beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. Furthermore, a heater is provided for heating the multi-aperture lens plate. Heating the multi-aperture lens plate can prevent and / or remove contamination, particularly for the beam-limiting apertures of the multi-aperture lens plate, thus reducing maintenance.

[0041] According to some embodiments, which can be combined with other embodiments described herein, at least two electrodes 124 interacting with the multi-aperture lens plate 122 and at least one extractor are provided. Each opening in the electrode 124 can be varied in size, i.e., diameter. Furthermore, the potentials of the extractor, the two or more electrodes, and the multi-aperture lens plate can be independently controlled. By adapting the distance between the electrodes, the size of the openings, and the potential, it is possible to control the aberration of the first-order beamlets in the collimator and the pitch of the first-order beamlets. It should be noted that, according to some embodiments, the distance and the size of the openings are designed, determined, and designed after manufacturing. Accordingly, for a specific design, the potentials can be varied during operation, while other parameters, for example, cannot be varied during operation. According to further embodiments, which can be combined with other embodiments described herein, the disadvantage of being unable to control the pitch or field curvature with only two electrodes between the extractor and the aperture plate can be overcome by providing three or more electrodes. Accordingly, having more than two electrodes allows the beamlet pitch to be matched to the collimator pitch, ie, the opening in the collimator 130 shown in FIG.

[0042] For example, field curvature correction can be provided so that the focal points of multiple primary beamlets lie in a plane perpendicular to the optical axis of the charged particle beam device or parallel to the collimator, such as plane 222 shown in Figure 3A.

[0043] According to some embodiments for irradiating or inspecting a specimen, the following operations can be provided: A primary charged particle beam is extracted from a charged particle beam source by an extractor; the primary charged particle beam is accelerated after the extractor; and the primary charged particle beam is decelerated toward a multi-aperture lens plate by two or more electrodes. For example, a first electrostatic field between the multi-aperture lens plate and the last of the two or more electrodes located upstream of the multi-aperture lens plate is smaller than a second electrostatic field between the penultimate electrode of the two or more electrodes and the last electrode. In light of the above, deceleration and optional acceleration can be provided so that Cs and Cc of the lens formed by the multi-aperture lens plate and the two or more electrodes are minimized and the pitch of the four or more primary beamlets in the collimator matches the collimator pitch of the collimator, particularly by providing appropriate diameters of the two or more electrodes 124. Furthermore, deceleration and optional acceleration can be provided so that the field curvature in the collimator is zero. Cc is the chromatic aberration coefficient of the lens, and Cs is the spherical aberration coefficient of the lens.

[0044] According to a further embodiment, which can be combined with other embodiments described herein, an extractor 314, three or more electrodes 124, for example five 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 three or more electrodes 124 provides at least one additional degree of freedom in primary beamlet control. Accordingly, the plane 222 (see FIG. 3A) at which each individual primary charged particle beamlet is focused can move along the length of the column. For example, the focal point of the primary beamlet (see, for example, plane 22 in FIG. 3A) can be adapted to be located downstream of the collimator.

[0045] According to a further embodiment, which can be combined with other embodiments described herein, moving the focus of the primary beamlets makes it possible to control the magnification of the beam source on the specimen.

[0046] The aperture lens array includes at least one aperture opening per beamlet. The aperture openings can be positioned on the multi-aperture lens plate 122 in any array configuration, such as a line, a rectangle, a square, a ring, or any suitable one- or two-dimensional array. For example, the beamlet array can be arranged in a line, a rectangle, or a square.

[0047] Illuminating the multi-aperture lens plate 122 with the primary charged particle beam results in several focused primary charged particle beamlets, for example by using a deceleration field in front of the multi-aperture lens plate. A lens or deflector array can be arranged at the focal plane of the primary charged particle beamlets. In these figures, some of the primary charged particle beamlets of the array of primary charged particle beamlets are shown after the lenses, while other primary charged particle beamlets are omitted from the drawings for a better view.

[0048] In some embodiments, the multi-aperture lens plate 122 can be directly illuminated by the charged particle beam emitter 111. According to some embodiments, "directly" can mean that no additional optical elements are provided between the charged particle beam emitter 111 and the multi-aperture lens plate, apart from two or more electrodes in embodiments having a field curvature correction electrode in front of the multi-aperture lens plate (when viewed in the direction of the propagating primary charged particle beam). The multi-aperture lens plate splits the primary charged particle beam emitted from the charged particle beam emitter into an array of primary charged particle beamlets. For example, the multi-aperture lens plate has at least three aperture openings to split the primary charged particle beam into at least three primary charged particle beamlets. In the example shown in FIG. 1, seven primary charged particle beamlets are shown in the schematic diagram. In some embodiments, the primary charged particle beamlets can be arranged in a one-dimensional array (linear), or a two-dimensional array (e.g., 4x4, 3x3, 5x5) or a rectangular array (e.g., 2x5). The embodiments described herein are not limited to these array examples and can include any suitable array configuration of primary charged particle beamlets.

[0049] The described multi-aperture lens plate can be beneficially 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 multi-aperture lens plate beneficially follows different criteria and must be considered in the context of the overall charged particle optical path design. In some embodiments, which can be combined with other embodiments described herein, a multi-aperture lens plate can be provided having one or more of the following characteristics: The number of aperture openings is a compromise between the largest possible total current and optical performance, particularly a spot size achievable with the largest possible beamlet field. Another boundary condition is beamlet separation on the specimen that reduces or avoids crosstalk while ensuring signal beamlet separation on the detector. According to further embodiments, which can be combined with other embodiments described herein, a grid configuration (i.e., the positions of the primary beamlets on the specimen and / or the positions of the aperture openings in the aperture plate) is provided that allows for complete coverage of the substrate surface area during scanning. The coverage is not limited to pure charged particle beamlet scanning, for example in the xy direction, but also includes mixed scanning operations such as charged particle beamlet scanning in a first direction, for example the x direction, and stage movement in another direction different from the first direction, for example the y direction.

[0050] FIGS. 5A and 5B illustrate an example of a multi-aperture lens plate 122 according to an embodiment of the present disclosure. Additionally, modifications of the aperture openings in the multi-aperture lens plate are illustrated in FIGS. 6A-6C. Modifications of the multi-aperture lens plate and / or aperture openings can be combined with other embodiments described herein. FIG. 5A illustrates a multi-aperture lens plate 122 having aperture openings 522. The aperture openings are arranged in an array. According to some embodiments, a square array or square pattern of aperture openings can be provided. As discussed above, other arrays or patterns can also be provided. For example, FIG. 5A illustrates a 3×3 array of aperture openings 522. In the case of a multi-aperture lens plate, an additional aperture 524 is provided. The additional aperture 524 can be considered a dummy aperture. Additional beamlets can be generated from the additional aperture 524, but the additional beamlets are not utilized in generating an image. The additional aperture provides an adjacent opening for the aperture opening 522. Accordingly, aperture openings 522 that should have no adjacent aperture openings on either side for a minimum number of openings are provided with adjacent further apertures, in order to have symmetrical properties, particularly for aperture openings that generate primary beamlets for image generation. In light of the above, it is possible to reduce hexapole effects or hexapole aberrations that may arise for aperture openings without adjacent apertures.

[0051] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more first-order beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. According to some embodiments, the apertures in the multi-aperture lens plate form an aperture array, and the number of apertures in the aperture array is greater than the number of first-order beamlets impinging on the specimen. Providing more aperture openings than the first-order beamlets impinging on the specimen enables reduced aberrations, particularly reduced octopole aberrations, for first-order beamlets located around the array of first-order beamlets.

[0052] According to some embodiments, which may be combined with other embodiments described herein, the array or pattern of perforated openings may be provided in a square or rectangular pattern. Additionally, a hexagonal pattern of perforated openings may be provided. The hexagonal pattern may be considered to be a honeycomb pattern.

[0053] As described above, it is beneficial to increase throughput for semiconductor wafer inspection and other applications. Accordingly, according to embodiments of the present disclosure, a multi-beam column is proposed. To further increase throughput, it is beneficial to increase the overall current of multiple beamlets on the specimen. Accordingly, 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 illuminated by the primary charged particle beam, respectively. Accordingly, it is beneficial to have large aperture sizes. 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 aperture opening pitch, e.g., the center-to-center distance. For example, the diameter of the aperture openings can be 70% or more compared to the aperture opening pitch.

[0054] As shown with respect to FIG. 6B, the aperture openings can have a round shape and thus a defined diameter. According to further embodiments, the aperture openings can have different shapes. Correspondingly, the aperture opening size can be 60% or more, particularly 70% or more, of the aperture opening pitch. For example, the aperture opening size 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, and a rectangular aperture opening has the size of the short side of the rectangle.

[0055] According to further embodiments that can be combined with other embodiments described herein, the size and shape of the aperture openings can be provided to have an aperture area in the multi-aperture plate (i.e., the sum of the areas of the apertures) that is 50% or more, particularly 70% or more, of the area of ​​the multi-aperture lens in the array of apertures.

[0056] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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, the size of the apertures in a first direction being at least 70% of the pitch of the apertures in the first direction. Two or more electrodes having one aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes a collimator for deflecting the first, second, third, and fourth primary beamlets of the four or more primary beamlets relative to each other. The charged particle beam device further includes a scanning deflector assembly for scanning four or more first-order beamlets across the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more first-order beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus the four or more first-order beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. By providing apertures with equally large sizes, the sum of the aperture opening areas is increased, thereby increasing the overall beam current of the first-order beamlets on the specimen. The signal-to-noise ratio of the imaging can be increased accordingly.

[0057] 5B shows an alternative arrangement of aperture openings 522 on the multi-aperture lens plate 122. The aperture openings may be arranged in a circle, which can reduce off-axis motion of optical elements common to primary charged particle beams or primary charged particle beamlets.

[0058] FIG. 6A illustrates one embodiment of the aperture opening 522. According to some embodiments, which can be combined with other embodiments described herein, the aperture opening can have a square or substantially square shape. The square or substantially square shape can reduce octopole effects or octopole aberrations that may occur relative to round aperture openings. Furthermore, the aperture opening shape can be substantially square and can include side edges 622 of the aperture opening. The side edges, particularly all four side edges, can have the same length. The corners 623 can be rounded. Accordingly, the average aperture can be a square with rounded corner edges. The rounded corners can further reduce octopole effects or octopole aberrations.

[0059] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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, the apertures being square in shape with rounded corners. Two or more electrodes having one aperture, for example, each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes a collimator for deflecting a first, second, third, and fourth primary beamlet of the four or more primary beamlets relative to each other. The charged particle beam device further includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more first-order beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. By providing the aperture with a square shape with rounded corners, aberrations for the first-order beamlets, particularly octopole aberrations, are reduced.

[0060] Collimator and multi-aperture (in box 230) According to embodiments of the present disclosure, which can be combined with other embodiments described herein, the collimator 130 and associated components can be located downstream of the ALA. The collimator 130 collimates the beamlets. Accordingly, a diverging pattern or array of primary beamlets is redirected by the collimator 130. For example, the primary beamlets can be parallel or essentially parallel after the collimator. According to some embodiments, which can be combined with other embodiments described herein, the collimator 130 can be located within or near the plane 222 shown in FIG. 3A. Near the plane should be understood to mean having the collimator 130 within 20% of the focal length of the ALA. By locating the plane 222, i.e., the focal plane of the ALA, within or near the collimator, distortion of the individual electron beams due to deflection aberrations can be reduced.

[0061] According to a further embodiment, magnification control can be provided by moving the plane 22 downstream of the ALA, as described above.

[0062] 7A, the collimator can include a deflector array 132 and a lens 232. According to further modifications, the collimator can include a deflector array or alternatively can include a lens 232. As described herein, a collimator can also refer to a collimator deflection structure, configured such that first-order beamlets from the aperture lens array emerge from the collimator parallel to one another.

[0063] According to some embodiments, which can be combined with other embodiments described herein, each beamlet can be deflected by an individual deflection electrode. Deflection electrodes are exemplarily shown in FIGS. 8A and 8B. FIG. 8A shows a deflector array 132 and an array of deflection electrodes 812. A pair of deflection electrodes is provided in the x-direction and the y-direction. Accordingly, individual collimation can be provided for each beam. For example, the deflection electrodes can be provided as a microelectromechanical system (MEMS) and can be provided on a wafer.

[0064] According to implementations of the present disclosure that can be combined with the embodiments described herein, multiple deflection electrodes, for example, four or eight, can be provided per primary beamlet. Each primary beamlet can be individually deflected. The collimator-deflection structure can include a segmented collimator. The collimator-deflection structure can include a segmented deflector for each of the primary beamlets.

[0065] According to a further embodiment, one or more deflector arrays may be provided along the axis of the charged particle beam column, as exemplarily shown in FIG. 8A. A stack of deflectors or deflector arrays may be provided, e.g., on one or more wafers, thereby simplifying the alignment of individual deflection electrodes for each beamlet. For example, a first deflection electrode 812 may deflect the beamlet in the x-direction, a second deflection electrode 814 may deflect the beamlet in the y-direction, and a third deflection electrode 816 may provide aberration correction, e.g., corrective astigmatism.

[0066] According to a further modification, which can be combined with other embodiments described herein, a deflector array for collimating the primary beamlets can be provided by electrode pairs that deflect two or more primary beamlets. For example, FIG. 9 shows elongated electrodes 912 for deflecting a row of primary beamlets along the y-direction and elongated electrodes 914 for deflecting a row of primary beamlets along the x-direction. FIG. 9 shows a top view of the deflector array 132 of the collimator 130. FIG. 10 shows a side view of the deflector array, showing, for example, the elongated electrodes 912 and the assigned electrodes 914. Furthermore, individual deflectors similar to those in FIGS. 8A and 8B can be provided. The individual electrodes can be provided for fine adjustment of the collimation or aberration correction.

[0067] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more primary beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. According to some embodiments, the collimator includes 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 the row of four or more primary beamlets along a second direction different from the first direction. Accordingly, the array of primary charged particle beamlets can be guided by a reduced number of electrodes, resulting in a reduced number of power supplies and power supply connections.

[0068] The individual deflectors of the deflector array can be realized by multipole elements of at least fourth order (quadrupole). According to some embodiments, the multipole elements can be manufactured by conventional machining. According to certain embodiments, which can be combined with other embodiments described herein, microelectromechanical systems (MEMS) technology deflector elements can be beneficial because they allow for higher multipole density and facilitate electrode wiring.

[0069] As mentioned above, a lens 232 may be provided in addition to the deflector array 132, as shown in FIG. 7A . According to some embodiments described in detail below, the deflector array 132 is disposed within or near the lens. According to some embodiments, the deflector array being disposed “in or near” the lens or “within” the lens is understood to mean that the deflector array is disposed within the focal length of the lens. In particular, the deflector array may be disposed within the lens. For example, the lens may include three electrodes, and the deflector array may be disposed between two of the three electrodes. According to some embodiments, the deflector array may be disposed at approximately the same height as the middle electrode of the three electrodes of the lens.

[0070] According to some embodiments, the lenses can be used to achieve the main function of deflecting the primary charged particle beamlets, in particular collimating the primary beamlets so that they emerge essentially parallel. The deflector array 132 can be used for fine-tuning the individual primary charged particle beamlets, in particular for fine-tuning the primary charged particle beamlets so that they are guided into or through a coma-free point of the objective lens. The charged particle beam device can include 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 lenses and deflector array.

[0071] According to some embodiments, which may be combined with other embodiments described herein, a lens 232 may be provided as an alternative to the deflector array 132. For example, the lens may include three electrodes.

[0072] According to some embodiments, lens 232 can be an acceleration lens, especially when two or more electrodes are driven in deceleration mode and / or when it is positioned in front of a multi-aperture lens plate (as viewed in the direction of the propagating primary charged particle beam). In some embodiments, lens 232 provided as an acceleration lens (or in other embodiments a deceleration lens) can be an electrostatic lens or a combined magnetic-electrostatic lens.

[0073] According to embodiments described herein, the primary charged particle beamlets are directed toward lens 232. For example, lens 232 can be an acceleration lens for accelerating the primary charged particle beamlets propagating from the multi-aperture lens plate. In embodiments in which two or more electrodes are positioned in front of the multi-aperture lens plate in the direction of the propagating primary charged particle beam, lens 232 can be used to accelerate the primary charged particle beamlets to a high column voltage. For example, the acceleration lens can accelerate the primary charged particle beamlets to a column voltage typically of 10 kV or more, more typically 20 kV or more. The acceleration voltage can determine the speed at which the charged particles of the charged particle beamlets travel down the column. In one example, the acceleration lens can be an electrostatic lens.

[0074] According to further modifications of the components in box 230 that 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 aperture lens array and the collimator 130. The coil can generate a positioning of the primary beamlets on the collimator aperture and / or rotate the array of primary beamlets. Furthermore, additionally or alternatively, a quadrupole field can be provided to correct the pitch of the array of primary beamlets in the x and / or y directions.

[0075] FIG. 7A shows an alignment deflector 716 acting in common on multiple primary beamlets. FIG. 7A shows an alignment deflector for a first direction. Additional alignment deflectors can be provided for a second, different direction, e.g., orthogonal to the first direction. Additionally, alignment coils are provided to rotate the array of primary beamlets. The alignment deflector 716 can provide a deflection field (dipole field) in the x-direction, the y-direction, or a combination thereof. Additionally, the alignment deflector 716 can provide a quadrupole field acting on the array of primary beamlets. The pitch of the array of primary beamlets in the x-direction and / or the y-direction can be adjusted or aligned accordingly.

[0076] Although FIG. 7A shows the alignment deflector 716 having magnetic deflectors, the alignment deflector system can also comprise electrostatic deflectors or a combination of magnetic and electrostatic deflectors.

[0077] FIG. 7B shows an array of primary beamlets 701 in an alignment system 710. The alignment system can include two alignment coils for generating a first quadrupole field in a first direction (see arrows in FIG. 7B). The alignment system can include two additional alignment coils 716 for generating a second quadrupole field in a second direction. The first and second directions can be rotated by approximately 45°. The shape of the array of primary beamlets 701 can be adapted accordingly. That is, the pitch of the primary beamlets can be adapted in two directions, for example, rotated by 45°, to adjust for distortions on the array of primary beamlets. The quadrupole field can be provided to correct the pitch of the array of primary beamlets in the x and / or y directions. The quadrupole field can compress the array in one direction and stretch the array in the orthogonal direction to adapt the pitch of the primary beamlets. Deflection and / or compression of the array of beamlets can be provided accordingly.

[0078] 7A illustrates an example implementation of an alignment system according to some embodiments. For example, a core 796 may be provided. The core has an opening through which an array of primary beamlets passes. Multiple alignment coils 716 may be provided in the core 796, including all deflection alignment coils and an alignment coil providing a quadrupole field. Accordingly, a field having dipole and quadrupole portions may be provided for combined deflection of the array and pitch adjustment of the array.

[0079] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more first-order beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. The charged particle beam device further includes an alignment system disposed between the multi-aperture lens plate and the collimator, the alignment system including at least one quadrupole for adjusting the pitch between the four or more first-order beamlets. The pitch of the first-order beamlets of the array of first-order beamlets can be adjusted in the collimator accordingly.

[0080] According to further embodiments, which can be combined with other embodiments described herein, one or more additional aperture arrays 140 can be provided. For example, FIG. 7A shows a first aperture array 140 located downstream of the collimator 130 and a second aperture array 740 located upstream of the collimator 130. 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 exemplarily shown in FIG. 7A, the number of apertures in the aperture array 140 and / or the number of apertures in the array 740 are smaller compared to the number of aperture openings in the multi-aperture lens plate 122. As described above with respect to FIG. 5A, aperture openings 522 and dummy apertures 524 for the primary beamlets can be provided. The dummy apertures reduce aberrations in the ALA. The dummy apertures are not intended to generate primary beamlets that impinge on the specimen. Accordingly, the aperture array 740 can include a portion that blocks the charged particle beam from passing through the dummy apertures 524. Accordingly, the multi-aperture lens plate includes a larger number of apertures compared to the number of apertures in the one or more further aperture arrays or in the deflector array of the collimator.

[0081] FIG. 7A illustrates further embodiments that can be combined with other embodiments described herein, particularly embodiments with an alignment system 710. The aperture array 740 includes a conductive material 742. The conductive material 742 or conductive surface allows for measurement of the current potentially provided by the impact of primary beamlets on the aperture array. The current can be measured by a current meter 744. Accordingly, misalignment of one or more primary beamlets with respect to the collimator 130 can be detected based on charged particles impacting the conductive material. A measured current of zero corresponds to all primary beamlets being guided through the openings in the further aperture array 740. According to some embodiments that can be combined with other embodiments described herein, the alignment system 710 can enable four-degree-of-freedom adjustment, for example, based on current measurements. A quadrupole field can provide deflection in the x-direction, deflection in the y-direction, rotation about the z-axis, and pitch adjustment.

[0082] According to further embodiments, the conductive material 742 or conductive surface may include segments or portions of conductive material, each segment or portion corresponding to an individual aperture in the aperture array or a pattern of apertures in the aperture array, e.g., a row or column. Accordingly, the ability to measure the current for an individual aperture or pattern of apertures may aid in further improved alignment of the primary beamlets with respect to the alignment system 710.

[0083] Further implementation examples of current measurement on an aperture plate for primary beamlet alignment, particularly for the alignment system described with reference to FIGS. 7A-7C, can be described with reference to FIGS. 24A and 24B. FIG. 24A shows an aperture array 740. A plurality of aperture openings are provided within the aperture array, forming an array of apertures, indicated by dashed lines 703. The apertures have plates on which conductive surfaces or regions of conductive material 742 are provided. FIG. 24A shows four conductive surfaces, indicated by dashed lines. The four conductive surfaces may be insulated from one another. Anemometers may be connected to the conductive surfaces. A properly aligned array of primary beamlets passes through the openings in the aperture array. Accordingly, for a properly aligned array, no current is generated from the charged particles of the primary beamlets. The current in anemometer 744 increases depending on the number of primary beamlets impinging on the conductive surface, i.e., the conductive material 742. Correspondingly, the greater the number of primary beamlets that strike the conductive surface, the greater the current.

[0084] 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, for example, to provide four conductive surfaces. When controlling the alignment system, one or more primary beamlets move relative to the apertures in the aperture array, varying the current in one or more anemometers 744. According to one embodiment described with reference to FIG. 24A , segmenting the conductive material and connecting anemometers to the segments of the conductive material allows different currents to be determined for each anemometer. Accordingly, moving the array of primary beamlets, for example to the right in FIG. 24A , can increase the current measurement of the right anemometer. Evaluating the differences for different segments allows multiple positions of the primary beamlets relative to the apertures in the aperture array to be determined for a given set of control parameters of the alignment system. Varying the control parameters of the alignment system, i.e., scanning the primary beamlets across the surface of the aperture array, adapting the pitch between the primary beamlets, and / or rotating the array of primary beamlets, can provide current measurements for different control parameters. The orientation, position, and / or shape of the array of primary beamlets can be determined, and the control parameters can be set to result in an aligned array of primary beamlets such that all of the primary beamlets pass through the apertures of the aperture array.

[0085] According to another implementation that may additionally or alternatively be provided, one or more conductive surfaces may be provided on the aperture plate and outside the array of apertures indicated by dashed line 703 .

[0086] For example, a conductive surface can be provided adjacent one corner of the array of apertures. Illustratively, this can be the top right conductive surface shown in FIG. 24B or the corresponding conductive material 742. FIG. 24B further shows a highlight of the top right primary beamlet. By scanning the array of primary beamlets as indicated by arrow 749, the top right primary beamlet can be directed onto the conductive surface, for example, onto the conductive surface adjacent the corresponding corner of the array of primary beamlets. Current meter 744 can measure the current. Thus, by scanning the array of primary beamlets so that the current can be detected, the amount of deflection of the array of primary beamlets can be determined. A corresponding deflection can be provided for some primary beamlets, particularly those at the corners of the array of primary beamlets.

[0087] Scanning each of the corners on the conductive surface, for example, the four corners of the array shown in FIG. 24B , allows the position of each corner to be determined. According to embodiments described herein, scanning can be provided such that a corresponding beamlet strikes the conductive surface before other beamlets strike the conductive surface. According to one embodiment, beamlets for two or more corners can be directed onto the same conductive surface. According to an alternative embodiment, beamlets for each corner can be directed to a different conductive surface. For example, referring to FIG. 24B , beamlets for each corner can be directed to conductive material 742, i.e., to a corresponding conductive surface adjacent the respective corner.

[0088] According to some embodiments, which may be combined with other embodiments described herein, determining control parameters of the alignment system with respect to at least three angles allows for assessment of the scan position of the array of primary beamlets, potential distortion of the array of primary beamlets, and potential rotational orientation of the array of primary beamlets. Accordingly, according to embodiments of the present disclosure, the combination of the alignment system 710 and one or more current meters connected to one or more conductive surfaces on the aperture array allows for proper alignment of the array of primary beamlets with respect to the aperture array.

[0089] 25 shows a flow chart illustrating a corresponding method for aligning an array of primary beamlets. In operation 1252, a primary charged particle beam is generated by a charged particle source. In operation 1254, four or more primary beamlets are generated by a multi-aperture lens plate and two or more electrodes. The method for aligning a field of primary beamlets is described herein with respect to an implementation in which a single beam source generates the primary charged particle beam and the primary beamlets are generated by an aperture lens array. According to further embodiments, which can be combined with other embodiments described herein, alignment of the array of primary beamlets can be equally provided for an array of primary beamlets generated by an array of charged particle beam sources.

[0090] In operation 1256, a first primary beamlet, a second primary beamlet, a third primary beamlet, and a fourth primary beamlet of the four or more primary beamlets are deflected relative to one another by a collimator. In operation 1257, an alignment system located upstream of the collimator is controlled to scan the four or more primary beamlets across openings in the aperture array. Additionally, in operation 1258, current in one or more conductive surfaces is measured over the aperture array.

[0091] According to an embodiment described with reference to FIG. 24A , the alignment system can be controlled to minimize the current in one or more conductive surfaces. For example, one or more conductive surfaces can be provided between the openings in the aperture array. Additionally or alternatively, as described with reference to FIG. 24B , the alignment system can be controlled to increase the current in one or more conductive surfaces. In such an implementation, one or more conductive surfaces are provided outside the aperture array formed by the openings in the aperture array. According to a further embodiment, which can be combined with other embodiments described herein, after aligning the array of primary beamlets with the aperture array, the primary beamlets, or at least a portion of the primary beamlets, can reach the specimen, and a signal from the signal beamlet can be measured. The array of primary beamlets can be further aligned downstream of the aperture array by increasing the signal beamlet signal. For example, further alignment can be provided by the alignment system and / or by adjusting the individual deflection of the primary beamlets in the collimator.

[0092] Regarding the method for aligning an array of primary beamlets, controlling the alignment system may include one or more of the following control procedures: a) scanning four or more primary beamlets in at least a first direction in the plane of the aperture plate by a deflection field, in particular one deflection field; b) scanning four or more primary beamlets in a second direction orthogonal to the first direction in the plane of the aperture plate; c) adapting the pitch between the four or more primary beamlets in at least a third direction in the plane of the aperture plate by a quadrupole field; d) adapting the pitch between the four or more primary beamlets in at least a fourth direction in the plane of the aperture plate by a quadrupole field; and e) rotating the array formed by the four or more primary beamlets in the plane of the aperture plate. Control procedures a) and / or b), control procedures c) and / or d), and control procedure e) may be performed sequentially. In addition, these control procedures may be performed sequentially in an iterative manner.

[0093] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more first-order beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. According to some embodiments, a collimator is provided 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 flow meter is attached to at least one aperture array of the one or more aperture arrays. Accordingly, beam adjustment of the first-order beamlets at the collimator can be measured. Furthermore, the first aperture array above the collimator and the second aperture array below the collimator can limit the electric field, for example, the electrostatic field of the collimator. Furthermore, additionally or alternatively, the aperture arrays and corresponding holders for the aperture arrays can serve as vacuum isolation between the vacuum compartments. The apertures in the aperture arrays can serve as pumping apertures.

[0094] According to 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 into adjacent vacuum compartments. Figure 11 shows a charged particle beam device 100. The charged particle beam source 110 is provided in a first vacuum compartment 118. A vacuum pump 119 is provided in fluid communication with the vacuum compartment 118. The vacuum pump 119 evacuates the vacuum compartment 118. In the example shown in Figure 11, the aperture lens array or multi-aperture lens plate is each provided in the vacuum compartment 118. According to further embodiments, instead of the vacuum compartment 118, two vacuum compartments can be provided. Accordingly, the charged particle beam source 110 and the aperture lens array can be provided in separate compartments.

[0095] 11, a second vacuum compartment 138 may be provided. For example, the collimator 130 may be provided within the second vacuum compartment 138. According to a further modification, an aperture lens array may also be provided within 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.

[0096] According to some embodiments, which can be combined with other embodiments described herein, a holder 149 is provided for the further aperture array 140. The holder 149, in particular the holder 149 and the aperture array 140, separate the second vacuum compartment 138 from the third vacuum compartment 188. Accordingly, it is not possible to provide differential pumping of different vacuum compartments on either side of the holder and / or the further aperture array 140, respectively.

[0097] The third vacuum compartment 188 is fluidly connected to a vacuum pump 189. The third vacuum compartment can include an objective lens unit 170. Furthermore, 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 aperture array and / or a holder for the further aperture array. Having more than two vacuum compartments makes it possible to have regions of different pressure within the column of the charged particle beam device 100.

[0098]

[0006] Embodiments of the charged particle beam device according to the present disclosure provide for the irradiation or inspection of a specimen with multiple primary beamlets, the primary beamlets being generated from a single charged particle beam source, for example, by an ALA. According to further embodiments, which can be combined with other embodiments described herein, the primary beamlets travel through the charged particle beam device without a first primary beamlet of the array of primary beamlets intersecting with a second primary beamlet of the array of primary beamlets, particularly without intersecting primary beamlets generated within the charged particle beam device. Avoiding intersections avoids interactions between the primary beamlets. A larger beam current can provide the primary beamlets.

[0099] Beam Separation and Detection (in Box 250) The beam separation unit 160 and the detection unit 150 are described in more detail below with reference to box 250 in Figure 2. The beam separation unit 160 separates the primary beamlet from one or more signal beamlets. The signal beamlets are detected by the detection unit 150. Figure 12 shows a specimen 80. A primary beamlet 103 impinges on the specimen 80. When the primary beamlet 103 impinges, a signal beamlet 105 is generated. The primary beamlet 103 and the signal beamlet 105 are separated by the beam separation unit.

[0100] According to some embodiments, which can be combined with other embodiments described herein, the beam separation unit can be a Wien filter array having a magnetic deflector 162 and an electrostatic deflector 164. The deflection of the first-order beamlets by the magnetic deflector 162 is provided in a direction opposite to the deflection direction of the electrostatic deflector 164. Accordingly, the beam paths of the first-order beamlets before and after the beam separation unit are parallel or substantially parallel. In an exemplary arrangement shown in FIG. 12 , in which the magnetic deflector 162 and the electrostatic deflector 164 act in different planes along the optical axis of the first-order beamlets, a shift of the first-order beamlets can occur. In an arrangement in which the deflection fields of the magnetic deflector and the electrostatic deflector overlap, the first-order beamlets are not substantially deflected.

[0101] The primary beamlet 103 is focused onto the specimen 80 by the objective lens unit 170. The signal beamlet 105 passes through the objective lens in a direction substantially opposite to that of the primary beamlet 103. The Wien filter array deflects the signal beamlet 105 accordingly. The deflection of the Wien filter array is based on a change in the deflection direction of the magnetic deflector 162. Accordingly, the magnetic deflector 162 and the electrostatic deflector 164 act in the same direction on the signal beamlet 105.

[0102] The beam separation unit can also be considered as an electromagnetic deflection system for the separation of the primary and signal beamlets. For example, the signal beamlet can be deflected by an angle between 1° and 20°, in particular by an angle of 3° or less.

[0103] Considering a rectangular or square array of primary beamlets, an electromagnetic deflection system, for example, a Wien filter array, can be provided, as exemplarily shown in Figures 13, 14A, and 14B. The electrostatic deflector 164 can be provided by two or more elongated deflection electrodes. The deflection electrodes can be, for example, parallel to the paper plane in Figure 13. The deflection electrodes can be provided on both sides of the array of primary beamlets. Additional deflection electrodes can be provided between rows of primary beamlets. For example, having an array of primary beamlets including M (M≧1) rows of primary beamlets, M+1 electrodes can be provided. These electrodes are elongated to deflect one row of primary beamlets.

[0104] The magnetic deflector 162 can be provided by an array of coils. The coils 464 can be provided on the core 462. The coils 464 can be provided along a line and can be elongated in a direction perpendicular to the 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 in the array of primary beamlets can pass between two adjacent coils in the array of coils. Having an array of primary beamlets including N (N≧1) rows of primary beamlets can provide N+1 coils. For example, these coils can be wound around a magnetic core, e.g., having a magnetic material, to form a magnetic circuit and close the magnetic flux lines.

[0105] 15 shows a further embodiment of the beam separation unit 160. 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 shown in FIGS. 14A and 14B . The collimator 130 can be operated to guide the primary beamlets 103 at an angle to the optical axis of the objective lens unit. The beam separation unit can deflect the primary beamlets to be parallel or essentially parallel to the optical axis of the objective lens unit 170. The signal beamlets guided upward in the charged particle beam device are separated from the primary beamlets by the magnetic field 163 of the beam separation unit 160.

[0106] A beam separation unit 160 according to a further embodiment is shown in FIGS. 16A-16C. For example, three layers of magnetic material are provided. The magnetic material can be a material with high magnetic permeability, and the layers can form a magnetic circuit. As shown in FIG. 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 and second electrostatic deflectors. Embodiments of the present disclosure that refer to magnetic or electrostatic deflectors can also be referred to as magnetic or electrostatic deflector arrays, respectively. The magnetic deflector 162 and 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.

[0107] The first electrostatic deflector 164 and the second electrostatic deflector 164 include at least two electrodes between the array rows of the primary beamlets. The at least two electrodes may be a first electrode 165 and a second electrode 166. The first electrode 165 may be at a positive potential and the second electrode 166 may be at a negative potential, or vice versa. The at least two electrodes provide an electrostatic deflection field for the array rows of the beamlets. According to some embodiments of the present disclosure, which may be combined with other embodiments described herein, the at least two electrodes may be assigned electrodes or strip electrodes. Furthermore, in addition or alternatively, at least two electrodes may be provided between the array rows of the primary beamlets.

[0108] The magnetic deflector 162 (or magnetic deflector array) includes one electrode, for example, an elongated electrode or a strip electrode, between the rows of the array of primary beamlets. The one electrode of the magnetic deflector is surrounded by a coil. For example, the coil can have an insulated wire. The one electrode can also be called a core for generating a magnetic field, or the one electrode can provide the core for generating a magnetic field.

[0109] Embodiments of the present disclosure refer to arrays of primary beamlets and arrays of signal beamlets, respectively. The present disclosure refers to rows (as opposed to rows and columns) regardless of whether the rows are provided in the x-direction or the y-direction. It is understood that an array of a row can extend in a first direction and a row can also extend in a second direction orthogonal to the first direction. Due to the nature of electro-optical components, the orientation of the term "row" when utilized herein to describe arrays of primary beamlets and / or secondary beamlets will be well understood by those skilled in the art.

[0110] The provision of three electrode layers forms a magnetic circuit and provides a symmetrical arrangement along the direction of the optical axis of the beamlets.

[0111] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus the four or more primary beamlets on the specimen. 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 includes a stage for supporting the specimen. The charged particle beam device can include a detection unit having a detection surface. The one or more detection surfaces are disposed between beam paths of the four or more primary beamlets. For example, the detection surface can convert the signal beamlets into photons, and four or more photodetectors are provided for the detection unit. The beam separation unit can include a first electrostatic deflector, a second electrostatic deflector, and a magnetic deflector provided between the first and second electrostatic deflectors, and optionally, the first electrostatic deflector, the second electrostatic deflector, and the magnetic deflector form a magnetic circuit. As a further optional additional or alternative feature, the first electrostatic deflector and the second electrostatic deflector each include at least two elongated electrodes between the four or more rows of primary beamlets. Accordingly, a symmetric beam separation unit can be provided.

[0112] Referring again to FIG. 12 , the array of primary beamlets 103 can have a distance d. The pitch can be 200 μm or more, particularly 400 μm or more. At least a first pitch between the primary beamlets can be provided along a first direction, e.g., the x-direction. The electrodes of the electrostatic deflector 164 and / or the cores or electrodes of the magnetic deflector 162 can have a pitch similar to the first pitch. For example, the electrode pitch can be within ±10% of the first pitch. Furthermore, according to some embodiments, which can be combined with other embodiments described herein, the beam separation between the primary beamlets and the signal beamlets can be provided by 10% to 90% of the first pitch between the primary beamlets, particularly in the plane of signal detection of the signal beamlets.

[0113] As mentioned above, the charged particle beam device 100 includes 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 (shown in FIG. 12 ). According to some embodiments, the beam separation unit may include, for example, at least one magnetic deflector, a Wien filter, or any other electro-optical component, whereby electrons are guided away from the primary charged particle beamlet beam, for example with a velocity dependent on the Lorentz force.

[0114] The beam separation unit may be provided between the objective lens unit 170 and the detection unit 150. The detection unit 150 includes a plurality of detectors or detection surfaces 152. The detection unit may include a plurality of conversion units 153 that convert signal beamlets into photons. In particular, the conversion units 153 may be electron-photon conversion units. The conversion units 153 may include the detection surface 152, and in particular may include an array of fluorescent strips. The array of fluorescent strips may be provided in the plane of the conversion unit 153 adjacent to the primary beamlet or a row of primary beamlets. For example, the pitch of the array of fluorescent strips may be similar to the distance d or the first pitch of the primary beamlets. The primary beamlets 103 may pass through the fluorescent strips or the array of fluorescent strips of the conversion units, respectively. According to some embodiments, which can be combined with other embodiments described herein, the pitch of the primary beamlets 103 in the plane 157 of the detection surface 152, i.e. the distance d, the pitch of the fluorescent strip, and the pitch of the signal beamlets 105, can be the same or essentially the same. The signal beamlets travel at an angle to the optical axis of the objective lens unit, as shown schematically in Figure 12, and are deflected by the beam separation unit to project signal electrons onto the fluorescent strip or the detection surface 152 of the electron-photon converter unit 81.

[0115] According to some embodiments, which can be combined with other embodiments described in this specification, at least one fluorescent strip of the array of fluorescent strips is arranged between two adjacent rows of primary beamlets.

[0116] According to some embodiments described herein, the detection surface is arranged to project the signal beamlet, i.e., the signal electrons, onto one side adjacent to the primary charged particle beamlet. Accordingly, overlapping of the signal electron spots from adjacent primary charged particle beamlets can be reduced or prevented, thereby making it easier to detect and distinguish the signal beamlet resulting from the adjacent primary beamlet. Accordingly, the detection and evaluation of the signal beamlet from the surface of the sample can be faster, thereby increasing the throughput for inspecting the sample.

[0117] In the example shown in Figure 12, the conversion units, e.g., electron-photon conversion units, are arranged in a series of parallel fluorescent strips extending substantially in the Y direction. According to further embodiments, the electron-photon conversion units or the detection surface can be provided on a plate having through-holes for the primary charged particle beamlets. The plate can extend in the X and Y directions. The detection surface or fluorescent portion can be provided on the plate, or the plate can include fluorescent material. According to the present disclosure, the portion of such a plate extending between the through-holes in the X or Y direction, or the fluorescent material on such a portion of the plate, is also considered to be a fluorescent strip.

[0118] In the conversion unit 153, photons are generated when a signal beamlet is incident. The photons can be generated by a fluorescent strip or portion. At least some of the photons are guided from the conversion unit to a photodetector. The photons can be guided, for example, by an optical fiber 156. A first end of the optical fiber can be disposed adjacent to the conversion unit, coupled to the conversion unit, or attached to the conversion unit. Light, i.e., photons, are 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. A row of optical fiber arrays can be provided between rows of primary beamlet arrays. For example, the array of optical fibers can be provided between the arrays of primary beamlets in one of the x-direction and the y-direction.

[0119] According to some embodiments, which can be combined with other embodiments described herein, an array of fluorescent strips is provided, each fluorescent strip located adjacent to a primary beamlet. For example, the fluorescent strips can be located at a distance equal to the pitch of the primary beamlets in plane 157 of detection surface 152. An array of optical fibers or glass fibers is provided to transport the generated light to a photodetector, for example an array of photodetectors.

[0120] 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 include a conductive material. For example, the detection surface can be coated with a conductive material. The conductive material allows for removal of the electric charge generated on the detection surface.

[0121] Figure 12 shows beam separation and detection in the XZ plane, while Figure 17 shows the corresponding arrangement in the YZ plane. As can be seen, optical fibres 156 can be provided to guide photons from the conversion unit to the photodetector array 159. The optical fibres can be provided between the rows of the array of primary beamlets.

[0122] A photodetector array, such as a multi-sensor detector system, can be positioned at a distance from the array of primary beamlets, for example, in a direction perpendicular to the optical axis of the primary beamlets. The detection unit can include an array of fluorescent strips, each located adjacent to a primary beamlet or a row of primary beamlets. For example, the fluorescent strips can be located within a distance equal to the pitch of the primary beamlets in the plane of the detection surface. According to some embodiments, the fluorescent strips can be positioned adjacent to the primary charged particle beamlets. Preferably, at least one strip of the array of fluorescent strips is positioned between two adjacent primary beamlets. By positioning the fluorescent strips adjacent to the primary beamlets or even between two adjacent primary beamlets, the width of the multibeam charged particle column can be reduced. This allows multiple multibeam charged particle columns to be more easily positioned close to each other, allowing more multibeam charged particle columns to be positioned within a specific area on the sample. Accordingly, the surface of the sample can be inspected more quickly, thereby increasing the throughput for inspecting the sample.

[0123] According to some embodiments, which can be combined with other embodiments described herein, the photodetector arrays can each include multiple photodetectors, and in particular can include at least one photodetector per signal beamlet or optical fiber. For example, the photodetectors can be photodiodes or other electro-optical elements including PN junctions. Additionally or alternatively, the photodetectors can include photomultiplier tubes. An electrical signal is generated by the photodetectors. In particular, the array of photodetectors allows for the generation of one electrical signal per signal beamlet.

[0124] 18 shows a schematic top view in the plane of a conversion unit 153, for example an electron-photon converter unit. As shown in FIG. 17, the primary beamlets 103 are arranged in multiple rows, each extending in a first direction, the Y-direction in FIG. 17. The rows of primary beamlets 103 are arranged adjacent to each other in a second direction, the X-direction in FIG. 17. The fluorescent strips of the conversion unit 153 are arranged adjacent to a row of primary beamlets, for example at a distance equal to the pitch of the rows of primary beamlets in the conversion unit 153 or the detection plane, respectively. Openings or gaps between the fluorescent strips are arranged to allow the primary beamlets to pass through the plane of the detection plane.

[0125] The signal beamlets 105 generated when the primary beamlets impinge on the specimen are deflected by the beam separation unit, for example in the x-direction in FIG. 18. The signal beamlets impinge on the detection surface, i.e., on a fluorescent strip or part of the conversion unit. The detection surface is on the side facing the beam separation unit. The conversion unit converts the signal beamlets into photons (light) using fluorescent material. On the side opposite the detection surface, an optical fiber 156 can be provided to collect the generated photons or at least a portion of the generated photons.

[0126] An optical fiber 156, positioned to collect photons onto various spots of the signal beamlet on a specific fluorescent strip, is positioned above said fluorescent strip, specifically in the ZY plane of Figure 18. As shown schematically in Figure 17, the optical fiber 156 is bent or curved in the YZ plane to position the second end of the fiber at a photodetector array 159.

[0127] As an alternative to the curved or bent optical fiber 156 shown in FIGS. 17 and 18, 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 of 10° to 60° relative to the central axis CA of the optical fiber. A fluorescent plate or layer is disposed at the tapered end 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 into the first end of the optical fiber and transported or guided through the optical fiber toward a photodetector. The photons 20 are confined within the optical fiber by total internal reflection at the side of the optical fiber. The optical fiber 156' can be at least partially coated with a light-reflecting layer, as shown schematically for one of the fibers in FIG. 19.

[0128] Objective Lens Unit and Scan (in box 270) Figure 20A shows an objective lens unit 170. Various aspects, details, features, and modifications of the objective lens unit are described with respect to Figures 20A-20D. Corresponding embodiments can be combined with other embodiments described herein, particularly with embodiments described with respect to various portions of the charged particle beam column described herein.

[0129] The objective lens unit includes three or more electrodes with holes 272. The holes 272 form an array of holes. One hole or opening is provided for each single primary beamlet and / or beamlet. Accordingly, the array of holes corresponds to an array of primary beamlets. As shown in FIG. 20A, an optical axis OA is provided for each primary beamlet. The three or more electrodes form an electrostatic lens component.

[0130] According to embodiments of the present disclosure, an insulating plate 174 is provided between two of the three or more electrodes. According to some embodiments that can be combined with other embodiments described herein, the insulating plate 174 includes one opening for passing two or more primary beamlets, particularly one opening for passing all primary beamlets through the one opening in the insulating plate 174. The three or more electrodes are biased to different potentials to form a lens field for the primary beamlets. In particular, according to some embodiments that can be combined with other embodiments described herein, the electrodes are configured to generate a deceleration field for decelerating the primary beamlets traveling toward the specimen. For example, the deceleration field between the penultimate electrode and the last electrode can be at least 5 kV / mm.

[0131] According to some embodiments, which can be combined with other embodiments described herein, one or more of the three or more electrodes can be electrodes 172, as shown in FIG. 20B. The electrodes 172 include holes 272 or openings, particularly an array of holes. The electrodes 172 are configured to provide a common potential around each of the holes 272. The electrodes 172 provide a common potential for the array of primary beamlets. As shown in FIG. 20A, the electrodes 172 can be connected to a power supply 173 or a controller. Each of the electrodes is biased to a potential. In particular, adjacent electrodes 172 (adjacent along the optical axis) can be biased to different potentials to generate a lens field.

[0132] According to some modifications, one or more of the three or more electrodes can be electrodes 176, as shown in FIG. 20C. The electrodes 176 include holes 272 or openings, particularly the region of the holes. Different potentials can be provided to each of the holes or openings, as indicated by the conductive portions 276, where the holes 272 can include individual conductive portions. The electrodes 176 are connected to a power source 177 or a controller. The power source or controller can control the potential of each individual conductive portion. The ability to provide different potentials to different openings makes it possible to provide fine tuning of the lens field for each primary beamlet, for example, for each primary beamlet individually. FIG. 20C shows the conductive portions 276 for each of the holes 272. According to further embodiments, which can be combined with other embodiments described herein, some of the openings can have a common conductive portion 276, thus biasing some of the openings to the same potential. Furthermore, at least two individual conductive portions are provided. At least a first conductive portion of the first hole 272 can be biased to a first potential, and at least a second conductive portion of the second hole can be biased to a second potential different from the first potential.

[0133] FIG. 20D shows further electrode modifications that can be combined with other embodiments described herein. The electrodes of the objective lens unit 170 can include four or more, e.g., eight, deflection electrodes 178. The deflection electrodes 178 can be controlled to generate a deflection field for each primary beamlet in the XY plane. Furthermore, octopole and / or quadrupole fields can be generated for aberration correction. The electrodes with individual 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 individual biasing of the deflection electrodes. According to some embodiments, the electrodes with deflection electrodes can be fabricated as a microelectromechanical system (MEMS). MEMS technology deflectors allow for higher multipole densities and facilitate electrode wiring.

[0134] 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, having an array of holes 272. As described above, an insulating plate 174 can be provided between adjacent electrodes. One of the electrodes can include a deflection electrode 178, as described with respect to FIG. 20D. The example shown in FIG. 20A includes a first electrode 172, a second electrode 172, a third electrode 172, a first individual focusing electrode 176 having 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 the deflection electrode and the fourth electrode 172. The deflection field can be at least 5 kV / mm.

[0135] According to some embodiments, a charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets is provided. The charged particle beam device includes 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 having an aperture, for example, one aperture each for the primary charged particle beam or the four or more primary beamlets, are provided, and the two or more electrodes and the multi-aperture lens plate can be biased to provide a focusing action. The charged particle beam device further includes 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 includes a scanning deflector assembly for scanning the four or more primary beamlets over the surface of the specimen, and an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more primary beamlets. The apertures are spaced apart by an aperture distance, and the objective lens unit is configured to focus four or more primary beamlets onto the specimen. According to some implementations, the objective lens unit can be further configured to focus four or more signal beamlets onto the detection plane. The charged particle beam device further includes a stage for supporting the specimen. At least one of the three or more electrodes of the objective lens unit includes four or more deflection electrodes per primary beamlet, each having an aperture for one primary beamlet, and a stage for supporting the specimen. Accordingly, the beam positions of the individual primary beamlets can be adjusted on the specimen.

[0136] According to embodiments described herein, the primary charged particle beamlets are focused by the objective lens unit 170 at separate locations on the specimen 80 to simultaneously inspect the specimen at those separate locations. The objective lens unit 170 can be configured to focus the primary charged particle beamlets onto the specimen, and the objective lens is a deceleration-type lens. For example, the deceleration-type lens can decelerate the primary charged particle beamlets to a predetermined incident energy. In some embodiments, the energy reduction from the column energy to the incident energy on the specimen is at least a factor of 10, such as at least a factor of 30. In one example, the incident energy is typically between about 100 eV and 8 keV, more typically 2 keV or less, such as 1 keV or less, such as 500 eV or even 100 eV.

[0137] As exemplarily shown in FIG. 2 , a scan deflector assembly 271 may be provided adjacent to or within the objective lens unit 170. The scan deflector 271 may provide a scan field for the array of primary beamlets. For example, it may provide a scan field for each of these beamlets individually. For example, the scan deflector assembly 271 may be a magnetic scan deflector assembly. According to further modifications, an electrostatic scan deflector assembly may additionally or alternatively be provided. According to some embodiments, the scan deflector assembly may be provided between the objective lens unit 170 and the beam separation unit 160. The scan deflector assembly may additionally or alternatively be provided between two of the two or more electrodes of the objective lens unit 170.

[0138] Stage (inside Box 280) FIG. 21 illustrates a stage 180 that can be provided in a charged particle beam device 100 according to an embodiment of the present disclosure. The stage 180 includes a motion assembly 182. The motion assembly 182 includes drivers for moving the specimen 80 at least in the x-, y-, and z-directions. Accordingly, the specimen 80 can be moved relative to the optical axis of the objective lens unit 170, and the distance between the specimen 80 and the objective lens unit 170 can be adjusted. The stage 180 includes an insulating layer 184 and a conductive layer 186. The conductive layer 186 provides a surface for receiving the specimen. The conductive layer is provided between the specimen 80 and the insulating layer 184. As shown in FIG. 20A, the conductive layer 186 can be connected to a power supply 288. Accordingly, the wafer can be biased.

[0139] According to some embodiments, the insulating layer 184 insulates the specimen or wafer from ground. Accordingly, the specimen can be set to a high potential, e.g., at least 5 kV. Biasing the specimen allows for voltage application between components of the charged particle beam device while reducing the voltage in certain regions of the charged particle beam device, which is useful for electro-optical purposes. For example, the emitter 111 and specimen 80 can be biased to a negative voltage. Accordingly, other components between the emitter and specimen can be biased to a reduced (positive) voltage. Accordingly, two or more electrodes, ALAs, collimators, objective lens units, etc., no longer require high voltages in addition to lower voltages for deflection, aberration correction, focusing, etc.

[0140] An embodiment of a method for inspecting a specimen with four or more primary beamlets is described with reference to the flowchart shown in FIG. 22 . In operation 1221, a primary charged particle beam is generated by a charged particle source, and four or more primary beamlets are generated by a multi-aperture lens plate and two or more electrodes. Accordingly, an array of primary beamlets can be provided. In operation 1222, a collimator deflects 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 one another. For example, the primary beamlets can be deflected to be parallel. In operation 1223, a scanning deflector assembly scans the four or more primary beamlets across a surface of the specimen, and the objective lens unit focuses the four or more signal beamlets on the specimen to generate four or more signal beamlets. In operation 1224, the four or more signal beamlets are focused onto a detection plane having a detection distance, one or more detection planes being positioned between each of the four or more primary beamlets. In operation 1225, the beam separation unit separates the four or more signal beamlets from the four or more first-order beamlets, and the four or more signal beamlets are guided to the detection plane at a detection distance. According to embodiments of the present disclosure, the beamlet distance can be 200 μm or more, particularly 400 μm or more. Accordingly, the opening in the objective lens unit can be 200 μm or more, particularly 400 μm or more. According to embodiments of the present disclosure, the detection distance can be 200 μm or more, particularly 400 μm or more. Accordingly, the detection distance can provide a pitch between the detection planes, and / or the signal beamlets impinge on the detection plane at the detection distance. According to some embodiments, which can be combined with other embodiments described herein, the detection distance corresponds to the pitch between the first-order beamlets, particularly in the plane of the detection unit. Furthermore, according to additional or alternative modifications, the spot size of the four or more signal beamlets at the detection plane can be adjusted, particularly the detection distance being larger than the spot size of the four or more signal beamlets on the detection plane.

[0141] Some embodiments of the present disclosure provide a beamlet distance or aperture distance, at which the apertures in the electrodes of the objective lens unit are spaced apart, of 200 μm or more, particularly 400 μm or more. Accordingly, the apertures can have a size of, for example, 100 μm or more, particularly 200 μm or more. Thus, the number of signal electrons that can be guided and / or focused onto the detection surface provides improved detection efficiency. For example, the detection distance, i.e., the distance of the detection surface, can be similar to the aperture distance. Furthermore, the electrodes of the objective lens unit can focus the signal beamlet onto the detection surface. Accordingly, the size of the apertures in the electrodes of the objective lens unit and the corresponding aperture distance, optionally in combination with the focusing of the signal beamlet, provide advantageous collection efficiency.

[0142] According to some embodiments, which can be combined with other embodiments described herein, the primary beamlets can be deflected and / or astigmatism corrected in an objective lens unit having four or more deflection electrodes per primary beamlet. Additionally or alternatively, the specimen can be biased on a stage supporting the specimen, the stage having an insulating layer.

[0143] According to some embodiments, the energy in the charged particle beam device varies depending on the location in the charged particle beam device. An example is given below. For example, in the configuration exemplarily shown in FIGS. 3A and 3B , where two or more electrodes 124 are used in deceleration mode before the multi-aperture lens plate 122, 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 before the array. After the multi-aperture lens plate and before the collimator, the energy in the column of the charged particle beam device 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 incident energy of the primary charged particle beamlets (decelerated by the objective lens) can be below 1 keV, for example, about 300 eV.

[0144] Additionally, charged particle beam devices and methods for inspecting specimens with charged particle beam devices according to embodiments described herein provide a small spot size of the primary charged particle beamlets on the specimen. It will be understood that the spot size is the diameter of the area on the specimen that is irradiated by a single primary charged particle beamlet. For example, the spot size of a single primary charged particle beamlet in an array of primary charged particle beamlets according to embodiments described herein can be typically less than 20 nm, more typically less than 10 nm, and even more typically less than 5 nm. According to some embodiments, the single primary charged particle beamlet can have a high current density due to the generation of an array of primary charged particle beamlets by a beam source according to embodiments described herein. The high current density helps to increase the signal-to-noise ratio and therefore the throughput of the charged particle beam device.

[0145] As described above, charged particle beam devices according to embodiments described herein enable the provision of an array of primary charged particle beamlets. According to some embodiments, the array of primary charged particle beamlets can typically include three or more primary charged particle beamlets per column, more typically ten or more primary charged particle beamlets. According to some embodiments described herein, charged particle beam devices according to embodiments described herein and methods of inspecting a sample with a charged particle beam device provide an array of primary charged particle beamlets in one column of the charged particle beam device, the primary charged particle beamlets having a distance from each other on the sample surface. For example, the distance between two primary charged particle beamlets in one column, i.e., adjacent charged particle beamlets in the row direction, can typically be 0.2 mm or more and / or 3 mm or less.

[0146] In some embodiments, two or more charged particle beam devices according to embodiments described herein can be arranged in a multi-column multi-beam microscope (MCM), with multiple columns each having an array of primary charged particle beamlets for examining a specimen, further increasing process speed and throughput.

[0147] 23 illustrates a charged particle beam device assembly in which three charged particle beam devices 100 according to embodiments of the present disclosure are provided in an array. According to some embodiments, one or more charged particle beam devices can be provided in an array, such as a one-dimensional array or a two-dimensional array. According to embodiments of the present disclosure, each charged particle beam device includes a charged particle beam source 110, two or more electrodes, i.e., electrodes having apertures for primary charged particle beams or having apertures 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, which may additionally or alternatively include various modifications described with respect to each other in this disclosure.

[0148] 23 includes multiple columns, each with multiple beamlets therein. The multiple columns are arranged above a specimen stage having a specimen 80. Accordingly, the multi-column multi-beam instrument can be configured to inspect a specimen, sample, or wafer, particularly a single specimen.

[0149] Embodiments of the present disclosure provide multiple advantages, some of which are described as follows: throughput for EBI can be increased, particularly in light of improved collection efficiency of signal electrons; aberrations, particularly octopole aberrations, can be reduced for first-order beamlets at the periphery of the array of first-order beamlets; the overall beam current of the first-order beamlets on the specimen can be increased, thereby increasing the signal-to-noise ratio for imaging; aberrations, particularly hexapole aberrations, for the first-order beamlets can be reduced; contamination, particularly on the beam-limiting apertures of the multi-aperture lens plate, can be eliminated, thus reducing the need for maintenance; the pitch of first-order beamlets in the array of first-order beamlets can be adjusted in the collimator; beam alignment of the first-order beamlets in the collimator can be measured; and the beam position of each first-order beamlet can be adjusted on the specimen by the objective lens unit. Furthermore, crosstalk is reduced due to the separation of the first-order beamlets from the multi-aperture plate to impingement on the specimen.

[0150] While the above is directed to embodiments, other and further embodiments may be devised without departing from the scope of the invention, which is determined by the claims that follow.

Claims

1. 1. A charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets, 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 an aperture for the primary charged particle beam or the four or more primary beamlets, the two or more electrodes and the multi-aperture lens plate being biasable to provide a focusing action; 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 one another; a beam separation unit for separating the four or more primary beamlets from four or more signal beamlets; a detection unit having a detection surface, wherein one or more detection surfaces are arranged between beam paths of the four or more first-order beamlets; a scanning deflector assembly for scanning the four or more primary beamlets across a surface of the specimen; an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more first-order beamlets, the apertures being spaced apart by an aperture distance, the objective lens unit configured to focus the four or more first-order beamlets onto the specimen and the four or more signal beamlets onto the detection plane; and a stage for supporting the specimen.

2. Charged particle beam device according to claim 1, wherein the aperture distance is 200 μm or more, in particular 400 μm or more.

3. 3. The charged particle beam device according to claim 1, wherein the objective lens unit comprises four or more electrodes for adjusting the spot sizes of the four or more signal beamlets on the detection plane.

4. Charged particle beam device according to claim 3 , wherein the spot size of the four or more signal beamlets is adapted to a detection distance, in particular a detection distance similar to the aperture distance.

5. The beam separation unit a first electrostatic deflector; a second electrostatic deflector; 5. The charged particle beam device according to claim 1, further comprising a magnetic deflector provided between the first electrostatic deflector and the second electrostatic deflector.

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

7. 7. The charged particle beam device according to claim 5, wherein the first electrostatic deflector and the second electrostatic deflector each include at least two elongated electrodes between rows of the four or more primary beamlets.

8. 8. The charged particle beam device according to claim 1, wherein the plurality of apertures in the multi-aperture lens plate form an aperture array, and the number of apertures in the aperture array is greater than the number of primary beamlets impinging on the specimen.

9. 9. The charged particle beam device according to claim 1, wherein the plurality of apertures in the multi-aperture lens plate have a square shape or an essentially square shape, and the essentially square shape is a square shape with rounded corners.

10. a heater for heating the multi-aperture lens plate; The charged particle beam device according to any one of claims 1 to 9, further comprising:

11. an alignment system disposed between the multi-aperture lens plate and the collimator; The charged particle beam device according to any one of claims 1 to 10, further comprising:

12. Charged particle beam device according to claim 11, wherein the alignment system comprises at least one quadrupole for adapting the pitch between the four or more primary beamlets.

13. further comprising one or more aperture arrays between the multi-aperture lens plate and the objective lens unit, the one or more aperture arrays each having a plurality of apertures for the four or more first-order beamlets. Charged particle beam device according to claim 12.

14. 14. The charged particle beam device of claim 13, wherein the collimator is provided between a first array of apertures of the one or more arrays of apertures and a second array of apertures of the one or more arrays of apertures.

15. a current meter attached to one or more conductive surfaces on at least one of the one or more aperture arrays; Charged particle beam device according to claim 13 or 14, further comprising:

16. 16. The charged particle beam device of claim 15, wherein the alignment system is provided between the multi-aperture lens plate and the at least one aperture array.

17. further comprising an aperture array holder for at least one of the one or more aperture arrays, the aperture array holder separating a first vacuum compartment from a second vacuum compartment; Charged particle beam device according to claim 13 or 14.

18. The collimator is 18. The charged particle beam device according to claim 1, comprising 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 different from the first direction.

19. 19. The charged particle beam device according to any one of claims 1 to 18, 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 so that they emerge from the collimator parallel to one another.

20. The objective lens unit is 20. The charged particle beam device according to claim 1, further comprising one or more insulating plates provided between two of the three or more electrodes, the one or more insulating plates having an opening for passing the four or more primary beamlets through the opening of the insulating plate.

21. 21. The charged particle beam device of claim 20, wherein the one or more insulating plates are configured to provide a deceleration field for decelerating the primary beamlets traveling towards a specimen, the deceleration field between the penultimate electrode and the last electrode being at least 5 kV / mm.

22. Charged particle beam device according to any one of claims 1 to 21, wherein at least one of the three or more electrodes of the objective lens unit comprises four or more deflection electrodes per primary beamlet, in particular eight or more deflection electrodes per primary beamlet.

23. 23. The charged particle beam device of claim 22, wherein each of the four or more deflection electrodes is connected by an insulated wire to allow individual biasing of the deflection electrodes.

24. Charged particle beam device according to claim 23, wherein the insulated wires are connected to a connector on the side of an array formed by the four or more primary beamlets.

25. The stage for supporting the specimen Charged particle beam device according to any one of the preceding claims, comprising an insulating layer configured to allow biasing of the specimen.

26. A first charged particle beam device according to any one of claims 1 to 25; a second charged particle beam device for irradiating or inspecting a specimen with an array of primary beamlets, said 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 an aperture for the primary charged particle beam or the four or more primary beamlets, the two or more electrodes and the multi-aperture lens plate being biasable to provide a focusing action; 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 one another; a beam separation unit for separating the four or more primary beamlets from four or more signal beamlets; a detection unit having a detection surface, wherein one or more detection surfaces are arranged between beam paths of the four or more first-order beamlets; a scanning deflector assembly for scanning the four or more primary beamlets across a surface of the specimen; an objective lens unit having three or more electrodes, each electrode having an aperture for the four or more first-order beamlets, the apertures being spaced apart by an aperture distance, the objective lens unit configured to focus the four or more first-order beamlets onto the specimen and the four or more signal beamlets onto the detection plane; Charged particle beam device assembly.

27. 27. The charged particle beam device assembly of claim 26, wherein the first charged particle beam device and the second charged particle beam device are positioned adjacent to each other above the specimen so as to simultaneously irradiate or inspect different portions of a surface of the specimen.

28. 1. A method for inspecting a specimen with four or more primary beamlets, comprising: generating a primary charged particle beam by a charged particle source; generating the four or more first-order 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 first order beamlets relative to one another by a collimator; scanning the four or more first-order beamlets across a surface of the specimen with a scanning deflector assembly; focusing the four or more first-order beamlets onto the specimen with an objective lens unit to generate four or more signal beamlets, each electrode of the objective lens unit having an aperture for the four or more first-order beamlets, the apertures being spaced apart by an aperture distance; focusing the four or more signal beamlets onto detection planes, one or more detection planes being positioned between respective first order beamlets of the four or more first order beamlets; separating the four or more signal beamlets from the four or more primary beamlets with a beam separation unit and directing the four or more signal beamlets to the detection plane.

29. 29. The method according to claim 28, wherein the opening distance is 200 μm or more, in particular 400 μm or more.

30. and adjusting a spot size of the four or more signal beamlets in the detection plane, in particular a detection distance is greater than the spot size of the four or more signal beamlets on the detection plane.

30. The method of claim 28 or 29.

31. further comprising heating the multi-aperture lens plate with a heater. The method according to any one of claims 28 to 30.

32. Controlling the alignment system upstream of the collimator to minimize the measured current or maximize the signal from the signal beamlet. The method of any one of claims 28 to 31, further comprising:

33. deflecting the first, second, third, and fourth primary beamlets of the four or more primary beamlets to be parallel with respect to each other; The method of any one of claims 28 to 32, further comprising:

34. the objective lens unit comprises three or more electrodes, and the method further comprises:

34. The method of any one of claims 28 to 33, further comprising decelerating the four or more primary beamlets between a penultimate electrode and a last electrode of the three or more electrodes, wherein the deflection field is at least 5 kV / mm.

35. deflecting and / or correcting the primary beamlets in the objective lens unit by four or more deflection electrodes per primary beamlet; The method of any one of claims 28 to 34, further comprising:

36. further comprising biasing the specimen on a stage supporting the specimen, the stage having an insulating layer. The method according to any one of claims 28 to 35.

37. extracting the primary charged particle beam from the charged particle beam source by an extractor; accelerating the primary charged particle beam after the extractor; and decelerating the primary charged particle beam toward the multi-aperture lens plate by the two or more electrodes, wherein a first electrostatic field between a last electrode of the two or more electrodes located upstream of the multi-aperture lens plate and the multi-aperture lens plate is smaller than a second electrostatic field between a penultimate electrode and a last electrode of the two or more electrodes. The method according to any one of claims 28 to 36.

38. 38. The method of claim 37, wherein the deceleration is provided such that Cs and Cc of the lens formed by the multi-aperture lens plate and the two or more electrodes are minimized and the pitch of the four or more first order beamlets in the collimator is matched to the collimator pitch of the collimator.

39. 39. A method according to claim 37 or 38, wherein the deceleration is provided such that the field curvature of the aperture in the collimator is zero.

40. 1. A method for aligning an array of four or more primary beamlets, comprising: generating a primary charged particle beam by a charged particle source; generating the four or more first-order 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 first order beamlets relative to one another by a collimator; controlling an alignment system upstream of the collimator to scan the four or more first-order beamlets across openings in an aperture array; measuring current at one or more conductive surfaces on the aperture array.

41. 41. The method of claim 40, wherein the alignment system is controlled to minimize current flow in the one or more conductive surfaces.

42. 42. The method of claim 41 , wherein the one or more conductive surfaces are provided between the openings in the aperture array.

43. The method of any one of claims 40 to 42, wherein the alignment system is controlled to increase the signal from a signal beamlet.

44. A method according to any one of claims 40 to 43, wherein the alignment system is controlled to maximise current in the one or more conductive surfaces.

45. 42. The method of claim 41, wherein the one or more conductive surfaces are provided outside an array of apertures formed by the openings in the array of apertures.

46. controlling the alignment system a) scanning the four or more first-order beamlets by a deflection field, in particular one deflection field, in at least a first direction in the plane of the aperture plate; b) scanning the four or more first-order beamlets in a second direction orthogonal to the first direction in the plane of the aperture plate; c) adapting the pitch between the four or more primary beamlets by a quadrupole field in at least a third direction in the plane of the aperture plate; d) adapting the pitch between the four or more primary beamlets by a quadrupole field in at least a fourth direction in the plane of the aperture plate; e) rotating the array formed by the four or more primary beamlets in the plane of the aperture plate.

47. 47. The method of claim 46, wherein control steps a) and / or b), control steps c) and / or d), and control step e) are performed sequentially.

48. 48. The method according to claim 46 or 47, wherein control steps a) and / or b), control steps c) and / or d), and control step e) are carried out iteratively in sequence.

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