Aperture assembly, beam manipulator unit, method for manipulating a charged particle beam, and charged particle projection apparatus.

Abstract

To provide a device and a method for operating a charged particle beam.SOLUTION: In one construction, an aperture assembly 370 containing a first aperture body 301 and a second aperture body 302 is provided. An aperture in the first aperture body is aligned with the aperture in the second aperture body. By this alignment, a charged particle beam can pass the aperture assembly. The first aperture body contains a first electrode system for applying a potential to an aperture circumference front surface of each aperture in the first aperture body. The first electrode system contains a plurality of electrodes. Each electrode is electrically insulated from the other electrode, and is electrically connected to the aperture circumference front surface of a different group from a plurality of groups of the aperture in the first aperture body at the same time.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] Cross-reference of related applications

[0001] This application claims priority to European Patent Application Publication No. 20168281.2, filed on 6 April 2020, which is incorporated herein by reference in its entirety.

[0002]

[0002] Embodiments provided herein generally relate to apparatus and methods for manipulating charged particle beams, particularly in the context of charged particle beam tools used for inspecting samples. [Background technology]

[0003]

[0003] When manufacturing semiconductor integrated circuit (IC) chips, undesirable pattern defects inevitably occur on the substrate (i.e., wafer) or mask during the manufacturing process, for example, as a result of optical effects and accidental particles, thereby reducing yield. Therefore, monitoring the extent of undesirable pattern defects is an important process in the manufacturing of IC chips. More generally, inspection and / or measurement of the surface of the substrate or other object / material is an important process during and / or after its manufacture.

[0004]

[0004] Pattern inspection tools using charged particle beams have been used to inspect objects, for example, to detect pattern defects. These tools generally use electron microscopy techniques such as scanning electron microscopes (SEMs). In an SEM, a primary electron beam of relatively high-energy electrons is targeted in a final deceleration step to land on the sample with a relatively low landing energy. The electron beam is focused onto the sample as a probing spot. The interaction between the material structure at the probing spot and the landed electrons from the electron beam causes electrons such as secondary electrons, backscattered electrons, or Auger electrons to be emitted from the surface. The generated secondary electrons may be emitted from the material structure of the sample. By scanning the primary electron beam as a probing spot across the sample surface, secondary electrons can be emitted across the sample surface. By collecting these emitted secondary electrons from the sample surface, an image representing the material structure features of the sample surface can be obtained.

[0005]

[0005] There is a general need to improve the throughput and other characteristics of inspection tools and methods that use charged particle beams. [Overview of the project]

[0006]

[0006] According to an aspect of the present invention, an aperture assembly for a beam manipulator unit of a charged particle projection apparatus is provided, the aperture assembly comprising a first aperture body and a second aperture body, wherein a plurality of apertures in the first aperture body are aligned with a corresponding plurality of apertures in the second aperture body, and this alignment allows each path of each plurality of charged particle beams to pass through the aperture assembly by passing through the respective apertures in the first aperture body and the second aperture body. The first aperture body includes a first electrode system for applying a potential to the aperture surface of each aperture within the first aperture body, and the second aperture body includes a second electrode system for applying a potential to the aperture surface of each aperture within the second aperture body, the first electrode system includes a plurality of electrodes, each electrode being electrically insulated from the other electrodes and simultaneously electrically connected to the aperture surfaces of different groups of apertures among a plurality of groups of apertures within the first aperture body.

[0007]

[0007] According to an aspect of the present invention, an aperture assembly for a beam manipulator unit of a charged particle projection apparatus is provided, the aperture assembly comprising a first aperture body and a second aperture body, wherein a plurality of apertures in the first aperture body are aligned with a corresponding plurality of apertures in the second aperture body, the alignment such that each path of each plurality of charged particle beams passes through the aperture assembly by passing through the respective apertures in the first aperture body and the second aperture body, each of at least a subset of apertures in the first aperture body being an elongated slit, and each corresponding aperture in the second aperture body being an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit.

[0008]

[0008] According to aspects of the present invention, a method is provided for manipulating a charged particle beam, the method comprising directing a plurality of charged particle beams through an aperture assembly to a sample, and electrostatically manipulating the charged particle beams by applying a potential to electrodes within the aperture assembly, wherein the aperture assembly comprises a first aperture body and a second aperture body, and the plurality of apertures within the first aperture body are aligned with the corresponding plurality of apertures within the second aperture body so that each of the charged particle beams passes through the aperture assembly by passing through the respective apertures within the first aperture body and the second aperture body, and the application of a potential comprises applying a potential to a plurality of electrodes, each of which is electrically insulated from one another and which is simultaneously electrically connected to the surrounding surface of apertures of different groups of apertures among a plurality of groups of apertures in the first aperture body.

[0009]

[0009] According to aspects of the present invention, a method for manipulating a charged particle beam is provided, the method comprising directing a plurality of charged particle beams through an aperture assembly to a sample, and electrostatically manipulating the charged particle beams by applying a potential to electrodes in the aperture assembly, wherein the aperture assembly comprises a first aperture body and a second aperture body, the plurality of apertures in the first aperture body being aligned with the corresponding plurality of apertures in the second aperture body such that each of the charged particle beams passes through the aperture assembly by passing through the respective apertures in the first and second aperture bodies, the application of a potential comprising applying a potential difference between the apertures in the first aperture body and the corresponding apertures in the second aperture body, each of at least a subset of the apertures in the first aperture body being an elongated slit, and each corresponding aperture in the second aperture body being an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit.

[0010]

[0010] According to an aspect of the present invention, an aperture assembly is provided for a manipulator unit of a charged particle multibeam projection system, the aperture assembly comprising: a first aperture body defining a first array of apertures; a second aperture body defining a corresponding array of apertures aligned with the first array of apertures to define the paths of each charged particle beam of a multibeam passing through the aperture assembly; a first electrode system associated with the first aperture body configured to apply a potential to the periphery surface of each aperture of the first aperture body; and a second electrode system associated with the second aperture body configured to apply a potential to the periphery surface of each aperture of the second aperture body, wherein the first electrode system comprises a plurality of electrodes, each electrode electrically insulated from the other electrodes and simultaneously electrically connected to the periphery surfaces of different groups of a plurality of groups of apertures of the first aperture body.

[0011]

[0011] According to an aspect of the present invention, an aperture assembly is provided for a beam manipulator unit of a charged particle multibeam projection apparatus, the aperture assembly comprising: a first aperture body defining a first plurality of apertures; and a second aperture body defining a plurality of corresponding apertures positioned with respect to the first plurality of apertures to define the paths of each charged particle beam of a multibeam through the aperture assembly, wherein each of at least a subset of the apertures in the first aperture body is an elongated slit, and each corresponding aperture of the plurality of apertures corresponding to the elongated slit is an opening having a smaller aspect ratio than the elongated slit.

[0012]

[0012] According to an aspect of the present invention, a beam manipulator unit for a charged particle multibeam projection system is provided, the manipulator unit comprising a lens including an up-beam lens aperture array having associated up-beam disturbance electrode arrays and a down-beam lens aperture array having associated down-beam disturbance electrode arrays, wherein the up-beam lens aperture arrays, down-beam lens aperture arrays and disturbance arrays are positioned relative to each other such that apertures in each array define the paths of each charged particle beam of the multibeam through the manipulator unit, and the up-beam and down-beam disturbance electrodes are controllable to apply disturbance fields to fields generated by the lens during operation.

[0013]

[0013] According to an aspect of the present invention, a method for manipulating a charged particle beam is provided, the method comprising: providing a lens including an up-beam lens aperture array having associated up-beam disturbance electrode arrays and a down-beam lens aperture array having associated down-beam disturbance electrode arrays; passing a plurality of charged particle beams through the respective apertures in the up-beam lens aperture arrays and the down-beam lens aperture arrays; and controlling the up-beam and down-beam disturbance electrodes to apply a disturbance field to the field generated by the lens.

[0014]

[0014] The above and other aspects of the present disclosure will become more apparent from the description of exemplary embodiments in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0015] [Figure 1]

[0015] This is a schematic diagram showing an exemplary charged particle beam inspection apparatus. [Figure 2]

[0016] Figure 1 is a schematic diagram showing an exemplary charged particle beam tool, which is part of an exemplary charged particle beam inspection system. [Figure 3]

[0017] Schematic diagram of a charged particle beam tool in which a sub-beam travels linearly between a condenser lens and an objective lens. [Figure 4]

[0018] Schematic diagram of a charged particle beam tool in which a collimator is provided between a condenser lens and an objective lens. [Figure 5]

[0019] Schematic diagram of a beam manipulator unit including an aperture assembly. [Figure 6]

[0020] Schematic diagram of a beam manipulator unit of the type shown in FIG. 4, in which an aperture assembly is integrated with a lens of a charged particle projection apparatus. [Figure 7]

[0021] Schematic top view of an exemplary first electrode system or second electrode system including a relatively wide and elongated conductive strip aligned in a first direction. [Figure 8]

[0022] Schematic top view of an exemplary second electrode system or first electrode system having a relatively wide and elongated conductive strip aligned in a second direction. [Figure 9]

[0023] Schematic top view of an exemplary first electrode system or second electrode system having a relatively narrow and elongated conductive strip aligned in a first direction. [Figure 10]

[0024] Schematic top view of an exemplary second electrode system or first electrode system having a relatively narrow and elongated conductive strip aligned in a second direction. [Figure 11]

[0025] Schematic top view of an exemplary first electrode system or second electrode system having a conductive element with a lower aspect ratio and filling without gaps. [Figure 12]

[0026] Schematic top view of an exemplary first electrode system or second electrode system having a conductive element including concentric loops. [Figure 13]

[0027] This is a schematic top view of a first or second electrode system, each comprising a single electrode electrically connected to all of the surrounding surfaces of the aperture of each aperture body. [Figure 14]

[0028] This is a schematic top view of a first or second electrode system, in which each electrode is electrically insulated from the other electrodes and electrically connected to the surrounding surface of each different aperture among a plurality of apertures within each aperture body. [Figure 15]

[0029] This is a schematic top view of an aperture assembly in which the uppermost aperture body includes a long, narrow slit. [Figure 16]

[0030] Figure 15 is a schematic side cross-sectional view of the unit along line XX. [Figure 17]

[0031] Figure 15 is a schematic side cross-sectional view of the unit along line YY. [Figure 18]

[0032] This is a schematic side cross-sectional view along line XX of the type of unit shown in Figure 15, where the lowest aperture body contains local integrated electronics for applying potential. [Figure 19]

[0033] This is a schematic side cross-sectional view of the unit in Figure 15 along line YY, where the lowest aperture body contains local integrated electronics for applying potential. [Figure 20]

[0034] This is a schematic top view of an exemplary first or second electrode system having elongated slits arranged radially. [Figure 21]

[0035] This is a schematic top view of an exemplary first or second electrode system having elongated slits aligned perpendicular to the radial direction. [Figure 22]

[0036] This is a schematic top view of an exemplary first or second electrode system having parallel, elongated slits aligned in a first direction. [Figure 23]

[0037] This is a schematic top view of an exemplary second electrode system or first electrode system having parallel, elongated slits aligned in a second direction. [Figure 24]

[0038] This is a schematic top view of an exemplary third electrode system, which has elongated slits aligned at a 45-degree angle to elongated slits in different aperture bodies within the electrode system. [Figure 25]

[0039] Figure 24 shows a schematic side cross-sectional view of a portion of an aperture assembly having a third electrode system configured as shown in Figure 24 and a fourth electrode system having a circular opening, viewed along a direction perpendicular to the elongated slit of the third electrode system. [Figure 26]

[0040] This is a schematic side cross-sectional view of the configuration shown in Figure 25, viewed along a direction parallel to the elongated slit of the third electrode system. [Figure 27]

[0041] This is an example of an electronic detection device integrated with a three-electrode objective lens. [Figure 28]

[0042] This is an example of an electronic detection device integrated with a two-electrode objective lens. [Figure 29]

[0043] This is a bottom view of the type of detector module shown in Figure 27 or Figure 28. [Figure 30]

[0044] This is a bottom view of an alternative detector module, where the beam aperture is a close-packed hexagonal array. [Figure 31]

[0045] A cross-sectional view of a part of the detector module is shown. [Modes for carrying out the invention]

[0016]

[0046] The following description will refer in detail to exemplary embodiments, examples of which are shown in the accompanying drawings. The following description will refer to the accompanying drawings, and unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described below in the description of exemplary embodiments do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with embodiments related to the present invention as described in the accompanying claims.

[0017]

[0047] Reducing the physical size of electronic devices and improving their computing power can be achieved by significantly increasing the density of circuit components such as transistors, capacitors, and diodes on an IC chip. This has been made possible by improvements in resolution, which allows for the fabrication of even smaller structures. For example, an IC chip in a smartphone available before 2019, the size of a thumbnail, could contain over 2 billion transistors, with each transistor being less than 1 / 1000th the size of a human hair. It is therefore not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. Even an error in a single step can dramatically affect the functionality of the final product. Just one "killer defect" can cause a device to fail. The goal of the manufacturing process is to improve the overall yield of the process. For example, to achieve a 75% yield for a process with 50 steps (where a step can represent the number of layers formed on a wafer), each individual step must have a yield of over 99.4%. If each individual step has a yield of 95%, the overall process yield is a low 7%.

[0018]

[0048] In IC chip manufacturing equipment, while high process yield is desirable, maintaining high substrate (i.e., wafer) throughput, defined as the number of substrates processed per hour, is also essential. High process yield and high substrate throughput can be affected by the presence of defects. This is especially true when operator intervention is required to investigate defects. Therefore, high-throughput detection and identification of microscale and nanoscale defects using inspection tools (such as scanning electron microscopes ("SEM")) is essential to maintain high yield and low costs.

[0019]

[0049] A SEM includes a scanning device and a detector. The scanning device includes an illumination device containing an electron source for generating primary electrons, and a projection device for scanning a sample, such as a substrate, with one or more focused beams of primary electrons. Together, at least the illumination device or illumination system and the projection device or projection system are sometimes referred to as an electron-optical system or apparatus. The primary electrons interact with the sample and generate secondary electrons. The detector captures the secondary electrons from the sample as it is scanned, so that the SEM can generate an image of the scanning area of ​​the sample. For high-throughput inspection, some inspection devices use multiple focused beams of primary electrons, i.e., multibeams. The component beams of a multibeam are sometimes called subbeams or beamlets. A multibeam can scan different parts of a sample simultaneously. Therefore, a multibeam inspection device can inspect a sample much faster than a single-beam inspection device.

[0020]

[0050] The following figures are schematic diagrams. Therefore, relative dimensions of components are enlarged in the drawings for clarity. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, illustrating only the differences to individual embodiments. While the description and drawings pertain to electro-optical devices, it should be understood that the embodiments are not used to limit this disclosure to specific charged particles. Therefore, references to electrons throughout this document can be considered general references to charged particles, where charged particles are not necessarily electrons.

[0021]

[0051] Refer to Figure 1 here. Figure 1 is a schematic diagram showing an exemplary charged particle beam inspection system 100. The charged particle beam inspection system 100 in Figure 1 includes a main chamber 10, a load lock chamber 20, a charged particle beam tool 40 (sometimes called an electron beam tool when electrons are used as charged particles), an instrument front-end module (EFEM) 30, and a controller 50. The charged particle beam tool 40 is located inside the main chamber 10.

[0022]

[0052] The EFEM30 includes a first loading port 30a and a second loading port 30b. The EFEM30 may include one or more additional loading ports. The first loading port 30a and the second loading port 30b may receive, for example, a front-opening unified pod (FOUP) containing a substrate (e.g., a semiconductor substrate or a substrate made of other materials) or a sample to be inspected (hereafter, substrates, wafers, and samples are collectively referred to as "samples"). One or more robotic arms (not shown) within the EFEM30 transport the sample to the load lock chamber 20.

[0023]

[0053] The load lock chamber 20 is used to remove gas from around the sample. This creates a vacuum, which is a local gas pressure lower than the ambient pressure. The load lock chamber 20 may be connected to a load lock vacuum pump system (not shown), which removes gas particles from within the load lock chamber 20. The operation of the load lock vacuum pump system allows the load lock chamber to reach a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) carry the sample from the load lock chamber 20 to the main chamber 10. The main chamber 10 is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas particles from within the main chamber 10 so that the pressure around the sample reaches a second pressure below the first pressure. After reaching the second pressure, the sample is carried to a charged particle beam tool 40, which can then be examined. The charged particle beam tool 40 may include a multibeam electron-optics device.

[0024]

[0054] The controller 50 is electronically connected to the charged particle beam tool 40. The controller 50 may also be a processor (such as a computer) configured to control the charged particle beam inspection apparatus 100. The controller 50 may also include processing circuits configured to perform various signal and image processing functions. In Figure 1, the controller 50 is shown as an external component of the structure, which includes the main chamber 10, the load lock chamber 20, and the EFEM 30, but it is understood that the controller 50 may also be part of the structure. The controller 50 may be located inside one of the component elements of the charged particle beam inspection apparatus 100, or the controller 50 may be distributed across at least two of the component elements. While this disclosure provides an example of a main chamber 10 housing an electron beam inspection tool, it should be noted that aspects of this disclosure are not, in a broad sense, limited to chambers housing electron beam inspection tools. Rather, it is understood that the principles described above can be applied to other tools and other arrangements of apparatus operating under a second pressure.

[0025]

[0055] Refer to Figure 2 here. Figure 2 is a schematic diagram showing an exemplary charged particle beam tool 40, which is part of the exemplary charged particle beam inspection apparatus 100 of Figure 1. The charged particle beam tool 40 (also referred to herein as apparatus 40) may include a charged particle source 201 (e.g., an electron source), a projection device 230, a motorized stage 209, and a sample holder 207. The charged particle source 201 and the projection device 230 may together be referred to as an electro-optical apparatus. The sample holder 207 is supported by the motorized stage 209 to hold a sample 208 (e.g., a substrate or mask) for inspection. The charged particle beam tool 40 may further include an electron detection device 240.

[0026]

[0056] The charged particle source 201 may include a cathode (not shown) and an extractor or anode (not shown). The charged particle source 201 may be configured to emit electrons from the cathode as primary electrons. The primary electrons are extracted or accelerated by the extractor and / or anode to form a charged particle beam 202 containing the primary electrons.

[0027]

[0057] The projection device 230 is configured to convert the charged particle beam 202 into multiple sub-beams 211, 212, and 213, and to guide each sub-beam onto the sample 208. While three sub-beams are shown for simplicity, there may be tens, hundreds, or even thousands of sub-beams. Sub-beams are sometimes called beamlets.

[0028]

[0058] The controller 50 can be connected to various parts of the charged particle beam inspection apparatus 100 in Figure 1, such as the charged particle source 201, the electronic detection device 240, the projection device 230, and the motorized stage 209. The controller 50 can perform various image and signal processing functions. The controller 50 can also generate various control signals to control the operation of the charged particle beam inspection apparatus 100, including the charged particle beam tool 40.

[0029]

[0059] The projection device 230 may be configured to focus sub-beams 211, 212, and 213 onto the sample 208 for inspection, forming three probe spots 221, 222, and 223 on the surface of the sample 208. The projection device 230 may be configured to deflect the primary sub-beams 211, 212, and 213 to scan the probe spots 221, 222, and 223 across individual scanning areas within a section of the surface of the sample 208. In response to the incidence of the primary sub-beams 211, 212, and 213 onto the probe spots 221, 222, and 223 on the sample 208, electrons, including secondary and backscattered electrons, may be generated from the sample 208. Secondary electrons generally have an electron energy of 50 eV or less. Backscattered electrons generally have an electron energy between 50 eV and the landing energy of the primary sub-beams 211, 212, and 213.

[0030]

[0060] The electron detection device 240 may be configured to detect secondary electrons and / or backscattered electrons and generate corresponding signals, which are sent to the controller 50 or a signal processing system (not shown) to construct, for example, an image of the corresponding scanning area of ​​the sample 208. The electron detection device 240 may be integrated into or separate from the projection device 230, and a secondary optical column may be provided to direct secondary electrons and / or backscattered electrons toward the electron detection device 240.

[0031]

[0061] The controller 50 may include an image processing system including an image acquirer (not shown) and a storage device (not shown). For example, the controller 50 may include a processor, computer, server, mainframe host, terminal, personal computer, any type of mobile computing device, or a combination thereof. The image acquirer may include at least some of the processing functions of the controller. Therefore, the image acquirer may include at least one or more processors. The image acquirer may be communicatively coupled to an electronic detection device 240 of the charged particle beam tool 40 that enables signal communication, such as a conductor, optical fiber cable, portable storage medium, IR, Bluetooth, the internet, wireless network, wireless radio, or a combination thereof. The image acquirer can receive signals from the electronic detection device 240, process the data contained in the signals, and construct an image therefrom. Therefore, the image acquirer can acquire an image of sample 208. The image acquirer can also perform various post-processing functions, such as contour generation and superimposition of indicators onto the acquired image. The image acquirer may be configured to adjust the brightness and contrast of the acquired image. The storage may be a storage medium such as a hard disk, flash drive, cloud storage, random access memory (RAM), or other types of computer-readable memory. The storage may also be combined with an image acquirer and can be used to save scanned raw image data as the original image or to save post-processed images.

[0032]

[0062] The image acquirer can acquire one or more images of a sample based on an imaging signal received from the electronic detection device 240. The imaging signal may correspond to a scanning operation for performing charged particle imaging. The acquired image may be a single image containing multiple imaging areas. The single image can be stored in storage. The single image may be the original image which can be divided into multiple regions. Each region may contain one imaging area containing features of sample 208. The acquired image may contain multiple images of a single imaging area of ​​sample 208 that have been sampled multiple times over a period of time. The multiple images can be stored in storage. The controller 50 may be configured to perform image processing steps using multiple images of the same location of sample 208.

[0033]

[0063] The controller 50 may include a measurement circuit (e.g., an analog-to-digital converter) to acquire the distribution of detected charged particles (e.g., secondary electrons). The charged particle (e.g., electron) distribution data collected during the detection time window can be used in combination with the corresponding scanning path data of the primary sub-beams 211, 212, and 213 incident on the sample surface to reconstruct an image of the sample structure under inspection. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 208. This allows the reconstructed image to reveal any defects that may be present in the sample.

[0034]

[0064] The controller 50 can control the motorized stage 209 to move the sample 208 during inspection of the sample 208. The controller 50 can enable the motorized stage 209 to move the sample 208 in a certain direction, preferably continuously, for example, at a constant speed, at least during the inspection of the sample. The controller 50 can control the movement of the motorized stage 209 so that the motorized stage 209 changes the speed of the movement of the sample 208, depending on various parameters. For example, the controller 50 can control the stage speed (including its direction) depending on the characteristics of the inspection step of the scanning process.

[0035]

[0065] A multibeam electron beam tool may be provided, including a primary projection unit, a motorized stage, and a sample holder. The primary projection unit may include an illumination unit. The primary projection unit may include one or more of the following components: an electron source, a gun aperture plate, a focusing lens, an aperture array, a beam manipulator (which may include a MEMS structure), an objective lens, and a beam separator (e.g., a Wien filter). The sample holder is supported by the motorized stage. The sample holder is configured to hold a sample (e.g., a substrate or a mask) for inspection.

[0036]

[0066] A multibeam electron beam tool may further include a secondary projection device and associated electron detection devices. The electron detection device may include multiple electron detection elements.

[0037]

[0067] The primary projection device is configured to irradiate the sample. In response to the incidence of the primary sub-beam or probe spot onto the sample, electrons are generated from the sample, including secondary electrons and backscattered electrons. The secondary electrons propagate in multiple secondary electron beams. The secondary electron beams typically contain secondary electrons (with electron energies of 50 eV or less) and may also contain at least some backscattered electrons (with electron energies between 50 eV and the landing energy of the primary sub-beam). A beam separator within the primary projection device may be configured to deflect the path of the secondary electron beam toward the secondary projection device. The secondary projection device then focuses the path of the secondary electron beam onto multiple elements of an electron detection device. The detection elements generate corresponding signals, which may be sent to a controller or signal processing system, for example, to construct an image of the corresponding scanning area of ​​the sample.

[0038]

[0068] Figures 3 and 4 are schematic diagrams illustrating a charged particle beam tool 40 according to one embodiment. The charged particle beam tool 40 includes a projection device 230. The charged particle beam tool 40 may be used as part of a charged particle beam inspection apparatus 100 as described above. The projection device 230 may be incorporated into other types of charged particle beam tools 40, such as the multibeam electron beam tool mentioned above.

[0039]

[0069] The projection device 230 includes a focusing lens array. The focusing lens array divides the beam 112 of charged particles into a plurality of sub-beams 114. In one embodiment, the focusing lens array focuses each of the sub-beams 114 to its respective intermediate focus 115.

[0040]

[0070] In the illustrated embodiment, the focusing lens array includes a plurality of beam apertures 110. The beam apertures 110 may be formed, for example, by openings in a substantially planar beam aperture body 111. The beam apertures 110 split the beam of charged particles 112 into a plurality of corresponding sub-beams 114. Depending on the embodiment, the charged particles include or consist of electrons. The charged particles are supplied by a charged particle source 201. The charged particle source 201 may or may not form part of the charged particle beam tool 40. The charged particle source 201 may be configured in any of the embodiments described above with reference to Figure 2. Thus, the charged particle source 201 may include a cathode (not shown) and an extractor or anode (not shown). The charged particle source 201 may include a high-luminance thermal field emitter with a desirable balance between luminance and total emission current.

[0041]

[0071] In the illustrated embodiment, the focusing lens array includes a plurality of focusing lenses 116. The plurality of focusing lenses 116 may be considered an array of focusing lenses and may lie in a common plane. Each focusing lens 116 may be associated with a corresponding aperture in the beam aperture 110. Each focusing lens 116 may, for example, be formed inside the beam aperture 110, or positioned directly adjacent to the beam aperture 110, and / or be integrated with a beam aperture body 111 (for example, the beam aperture body 111 may form one of the electrodes of the focusing lens 116). Thus, a plate or array forming the electrodes of the focusing lens array may also function as a beam aperture. The object forming the plate or array may be called an aperture body.

[0042]

[0072] The focusing lens 116 may include a multi-electrode lens. The lens array may take the form of at least two plates that function as electrodes, with apertures within each plate aligned with each other and corresponding to the position of the sub-beam. At least two of these plates are maintained at different potentials during operation to achieve the desired lensing effect. In one configuration, the focusing lens array is formed from an array of three plates, each having the same energy when a charged particle enters and exits each lens; this configuration is sometimes called an Einzel lens. An Einzel lens (including, for example, one that may be used in a focusing lens array) may also have electrodes (e.g., a plate array) arranged symmetrically with respect to each other, such that the inlet and outlet electrodes are equidistant from the electrodes between them. The inlet and outlet electrodes are also usually maintained at the same potential. In other configurations, the focusing lens is formed from four or more electrodes (e.g., a plate array) where a charged particle has the same energy when entering and exiting each lens. Such configurations may still have inlet and outlet electrodes kept at the same potential, and / or symmetrically arranged electrodes, but because they have four or more electrodes, these configurations may not be strictly considered Einzel lenses. Configuring lenses so that charged particles have the same energy when entering and exiting each lens (whether the lenses are strictly Einzel lenses or not) means that dispersion occurs only within each lens (between the inlet and outlet electrodes of the lenses), thereby limiting off-axis chromatic aberration. When the thickness of the focusing lens is thin, for example, a few millimeters, the effect of such aberrations is small or negligible.

[0043]

[0073] Each focusing lens 116 focuses one of the sub-beams 114 (for example, each different one) to its respective intermediate focal point 115. The intermediate focal points 115 of multiple focusing lenses 116 may lie in a substantially common plane, which is sometimes called the intermediate image plane 120.

[0044]

[0074] The projection device 230 further includes a plurality of objective lenses 118. The objective lenses 118 are located downstream of the intermediate focal point (and intermediate image plane 120). The plurality of objective lenses 118 may be considered as an array of objective lenses and may lie in a common plane. Each objective lens 118 projects one of the sub-beams 114 (from the corresponding focusing lens 116) onto the sample 208 under evaluation. Thus, there may be a one-to-one correspondence between the focusing lens 116 and the objective lenses 118, and each sub-beam 114 propagates between a pair of focusing lenses 116 and objective lenses 118 specific to that sub-beam. There may also be a corresponding one-to-one correspondence between the beam aperture 110 of the focusing lens array and the objective lenses 118.

[0045]

[0075] As illustrated in Figure 3, the projection system 230 may be configured such that the path 122 of each sub-beam 114 (for example, the principle ray of the sub-beam 114 corresponding to the beam axis of the sub-beam 114) is substantially straight from each focusing lens 116 to the corresponding objective lens 118 (i.e., to the objective lens 118 corresponding to that focusing lens 116). This straight path may further extend to the sample 208. Alternatively, as illustrated in Figure 4, a collimator 524 may be provided between the focusing lens 116 and the objective lens 118, for example, in the intermediate image plane 120. The collimator 524 parallelizes the sub-beams. Parallelizing the sub-beams reduces the field curvature effect in the objective lens 118, thereby reducing errors caused by field curvature, such as astigmatism and focus errors.

[0046]

[0076] In some embodiments, as illustrated in Figures 3 and 4, the projection apparatus 230 further includes one or more aberration correctors 124, 125, 126 for reducing one or more aberrations in the sub-beam 114. In one embodiment, each of at least a subset of aberration correctors 124 is located at or directly adjacent to one of the intermediate focal points 115 (e.g., located at or adjacent to the intermediate image plane 120). The sub-beam 114 has the smallest cross-sectional area at or near the focal plane, such as the intermediate plane 120. This provides the aberration correctors 124 with more space elsewhere, i.e., more space available for the up-beam or down-beam of the intermediate plane 120 (or more space available in an alternative configuration without the intermediate image plane 120). In one embodiment, the aberration correctors 124 located at or directly adjacent to the intermediate focal points 115 (or the intermediate image plane 120) include deflectors for correcting radiation sources 201 that appear to be in different positions for different beams. The corrector 124 may be used to correct macroscopic aberrations caused by the radiation source 201 that interfere with good alignment between each sub-beam 114 and the corresponding objective lens 118. The aberration corrector 124 can correct aberrations that interfere with proper column alignment. Such aberrations may also lead to misalignment between the sub-beam 114 and the corrector 124. For this reason, it may be desirable to place an aberration corrector 125 on or near the condensing lens 116 (for example, each of such aberration correctors 125 may be integrated with or directly adjacent to one or more of the condensing lenses 116). This is desirable because the condensing lens 116 is nearly perpendicular to or coincides with the beam aperture 110, so that at or near the condensing lens 116, aberrations have not yet caused a shift in the corresponding sub-beam 114. However, the challenge of placing the compensator 125 on or near the focusing lens 116 is that, compared to locations further downstream, the cross-sectional area of ​​each sub-beam 114 becomes relatively larger and the pitch becomes relatively smaller at this location.

[0047]

[0077] In some embodiments, as illustrated in Figures 3 and 4, each of at least a subset of aberration correctors 126 is integrated with or directly adjacent to one or more of the objective lenses 118. In one embodiment, these aberration correctors 126 reduce one or more of the following: field curvature, focus error, and astigmatism. In addition to or instead of this, one or more scanning deflectors (not shown) may be integrated with or directly adjacent to one or more of the objective lenses 118 to scan the subbeam 114 across the sample 208. Such a configuration may be implemented, for example, as described in European Patent Application Publication No. 2425444A1, which is incorporated herein by reference, in particular with respect to the disclosure of the use of aperture arrays as scanning deflectors.

[0048]

[0078] The aberration correctors 124, 125 may be individual CMOS-based programmable deflectors as disclosed in European Patent Application Publication No. 2702595A1, or arrays of multi-pole deflectors as disclosed in European Patent Application Publication No. 2715768A2, the descriptions of beamlet manipulators in both documents are incorporated herein by reference.

[0049]

[0079] In one embodiment, an aberration corrector, such as an aberration corrector 126 associated with the objective lens 118, includes a field curvature corrector that reduces field curvature. Reducing field curvature reduces errors caused by field curvature, such as astigmatism and focus errors. Without correction, significant field curvature aberration is expected to occur in the objective lens 118, as illustrated in Figure 3, due to the oblique angle of incidence to the objective lens 118, in embodiments where the sub-beam 114 propagates along a straight path between the focusing lens 116 and the objective lens 118.

[0050]

[0080] In one embodiment, the field curvature corrector is integrated with one or more of the objective lenses 118 or directly adjacent to them. In one embodiment, the field curvature corrector includes a passive corrector. The passive corrector may be implemented, for example, by changing the diameter and / or ellipticity of the aperture of the objective lens 118. The passive corrector may be implemented, for example, as described in European Patent Application Publication 2575143A1, which is incorporated herein by reference to a disclosure concerning the use of aperture patterns, particularly for correcting astigmatism. The passive nature of the passive corrector is desirable because it means that no control voltage is required. In embodiments in which the passive corrector is implemented by changing the diameter and / or ellipticity of the aperture of the objective lens 118, the passive corrector offers the further desirable feature that it does not require additional elements, such as additional lens elements. The challenge with passive correctors is that, since they are fixed, the required amount of correction must be carefully calculated in advance. In addition to or instead of this, in one embodiment, the field curvature corrector includes an active corrector. The active corrector can provide correction by controllably correcting charged particles. The correction applied by each active corrector may be controlled by controlling the potential of each of one or more electrodes of the active corrector. In one embodiment, a passive corrector provides coarse correction, and an active corrector provides finer and / or adjustable correction.

[0051]

[0081] An example of the beam manipulator unit 300 is described below. The beam manipulator unit 300 includes an aperture assembly 370. The beam manipulator unit 300 may be provided as part of one of the configurations of the projection device 230 described above. The beam manipulator unit 300 applies an effect to the charged particle beam passing through the beam manipulator unit 300. This effect may include correction of aberrations or multipole or focus errors associated with the charged particle beam. One or more of the aberration correctors 124, 125, and 126 described above can be implemented using the beam manipulator unit 300. Thus, the beam manipulator unit 300 may be positioned at each focal point of the intermediate focal point 115, or directly adjacent thereto. Alternatively or in addition to this, the beam manipulator unit 300 may be integrated with one or more of the objective lenses 118, or directly adjacent thereto. Alternatively, or in addition to the above, the beam manipulator unit 300 may be integrated with one or more of the focusing lenses 116, or directly adjacent to them.

[0052]

[0082] As illustrated in Figures 5 and 6, the aperture assembly 370 may include a first aperture body 301 and a second aperture body 302. The first aperture body 301 may, but is not necessarily, be in the up-beam of the beam path of the second aperture body 302. Multiple apertures 304 within the first aperture body 301 are aligned with corresponding multiple apertures 306 within the second aperture body 302. This alignment provides a charged particle path for each of the multiple charged particle beams. Following this charged particle path, each charged particle beam may pass through the aperture assembly 370 through the respective apertures in the first aperture body 301 and the second aperture body 302. When a charged particle beam is incident on the aperture assembly 370 at an oblique angle, aperture 306 in the second aperture body 302 may be laterally offset (i.e., not vertically aligned) with respect to the corresponding aperture 304 in the first aperture body 301. This lateral offset provides the necessary alignment with the path of the charged particle beam to allow it to pass through the aperture assembly 370. When a charged particle beam is incident on the aperture assembly 370 perpendicularly, aperture 306 in the second aperture body 302 may be positioned directly below (i.e., vertically aligned with) the corresponding aperture 304 in the first aperture body 301. An exemplary path of the charged particle beam is labeled 305 in Figures 5 and 6. The aperture 304 in the first aperture body 301 may have the same size and / or shape as the aperture 306 in the second aperture body 302. Alternatively, the aperture 304 in the first aperture body 301 may have a different size and / or shape from the aperture 306 in the second aperture body 302. Depending on the configuration, all of the apertures 304 and 306 may have a curved edge shape such as circular, elliptical, or egg-shaped, but other shapes are also possible. The first aperture body 301 and the second aperture body 302 may be substantially planar.Typically, the maximum in-planar dimension (e.g., diameter) of each aperture 304 within the first aperture body 301 is smaller than the separation distance between the first aperture body 301 and the second aperture body 302. However, in some embodiments, the maximum in-planar dimension (e.g., diameter) of each aperture 304 within the first aperture body 301 may be equal to or greater than the separation distance between the first aperture body 301 and the second aperture body 302 (for example, when the first aperture body 301 and the second aperture body 302 form part of an Einzel lens).

[0053]

[0083] An electric drive unit 320 is provided to apply a potential to at least the surrounding surface of the apertures 304, 306 defined within the first aperture body 301 and the second aperture body 302. This drive unit may be connected to one or both of the first aperture body 301 and the second aperture body 302 via a voltage source connection (not shown). Thus, during operation, multiple charged particle beams are directed through the aperture assembly towards the sample 208. The electric drive unit 320 may be provided, for example, as part of a charged particle projection system 230 and / or a beam tool 40 comprising a manipulator unit 300, or as part of the manipulator unit 300. The charged particle beam tool 40 may be used as part of a charged particle beam inspection apparatus 100 as described above. The electric drive unit 320 may be provided within a portion of the charged particle beam tool 40, which may be called an electro-optical system or apparatus, as described above.

[0054]

[0084] Embodiments are generally exemplified herein as having the first aperture body 301 located on the up beam of the second aperture body 302. However, the first aperture body 301 and the second aperture body 302 may be configured in reverse, with the second aperture body 302 located on the up beam of the first aperture body 301.

[0055]

[0085] The charged particle beam is manipulated by controlling the electric field within the region through which the charged particle beam passes using the aperture assembly 370. This is achieved by applying an appropriate potential to the electrodes of the aperture assembly 370.

[0056]

[0086] In some embodiments, the first aperture body 301 includes a first electrode system 311. The first electrode system 311 can be formed in various ways. The first electrode system 311 may be provided as an integral part of the first aperture body 301, as schematically shown in Figure 5. Alternatively, the first electrode system 311 may be provided as a conductive layer or structure on the first support structure 361, as schematically shown in Figure 6. In some cases, the first electrode system 311 may be formed using a silicon-on-insulator process. The first electrode system 311 may be provided as a conductive layer or structure on an insulating layer of silicon oxide. The first electrode system 311 may include a metallized layer and / or a conductive semiconductor such as silicon or doped silicon. The first electrode system 311 may include a metal such as molybdenum or aluminum. An example of the first electrode system 311 is shown in Figures 7 to 12 and is discussed below. The first electrode system 311 is configured to apply a potential to the aperture-surrounding surface of each aperture 304 of the first aperture body 301. The first electrode system 311 may include multiple electrodes. Each electrode may include a conductive element and / or a conductive track. Each electrode is electrically insulated from the other electrodes and is simultaneously electrically connected to the aperture-surrounding surface of different groups of apertures 304 in the first aperture body 301. Each group includes multiple apertures 304. Thus, each electrode can simultaneously apply a potential to multiple apertures 304, independently of the potential applied to other apertures 304 in the first aperture body 301. Consequently, fewer electrodes are required than if each electrode were connected to only one aperture. Fewer electrodes simplify electrode routing, thereby facilitating manufacturing and allowing for a more selectively denser aperture pattern within the electrodes. Independently controlling the potential applied to groups of apertures 304 provides a higher level of control than when all apertures are electrically connected together, such as when the apertures are formed on a single metal plate.Therefore, this leads to an improved balance between the ease of manufacturing the beam manipulator unit and the controllability of beam manipulation.

[0057]

[0087] In some embodiments, the second aperture body 302 includes a second electrode system 312. The second electrode system 312 applies a potential to the aperture-surrounding surface of each aperture 306 of the second aperture body 302. The second electrode system 312 may be configured in any of the embodiments described above for the first electrode system 311. Accordingly, the second electrode system 312 may include a plurality of electrodes formed on the second support structure 362. Each electrode is electrically insulated from the other electrodes and may be simultaneously electrically connected to the aperture-surrounding surfaces of different groups of apertures 306 of the second aperture body 302. Alternatively, the second electrode system 312 may include a single electrode electrically connected to all of the aperture-surrounding surfaces of the second aperture body 302. Therefore, the second electrode system 312 may be mounted as a single, integrated conductive plate such that the second aperture body 302 and the second electrode system 312 are provided by the same element (i.e., the second aperture body consists of the second electrode system 312).

[0058]

[0088] Depending on the embodiment, as illustrated in Figures 7 to 12, the same number of apertures 304 are provided within each of at least two groups of apertures 304 within the first aperture body 301. Alternatively, or in addition to this, the same number of apertures 306 may be provided within each of at least two groups of apertures 306 within the second aperture body 302.

[0059]

[0089] Depending on the embodiment, as illustrated in Figures 7 to 10, each electrode in the first electrode system 311 includes elongated conductive strips 322, 324, and / or each electrode in the second electrode system 312 includes elongated conductive strips 322, 324. Each elongated conductive strip in each electrode system may be mounted as opposing parallel plates. Preferably, the conductive strips 322, 324 in each electrode system are parallel to each other and / or substantially linear. Placing electrodes within the conductive strips 322, 324 in each electrode system facilitates routing because electrical connections to the conductive strips 322, 324 can be made at the ends of the conductive strips 322, 324. Depending on the configuration, the conductive strips 322, 324 are arranged to extend to the periphery of the first electrode system 311 or the second electrode system 312, as schematically shown in Figures 7 to 10. Extending the conductive strips 322 and 324 to the periphery means that electrical connections to the conductive strips 322 and 324 can be made at the periphery. The periphery of the electrode system shown in the figure is schematic. The shape and relative size of the peripheral surface may differ in the actual configuration. The peripheral surface may be dimensioned to include more apertures 304 and 306 than shown in the figure, for example.

[0060]

[0090] Depending on the embodiment, the aperture 304 in the first aperture body 301 and / or the aperture 306 in the second aperture body 302 are arranged in a regular array. The regular array has repeating unit cells. The regular array may include, for example, a square array, a rectangular array, or a hexagonal array. Alternatively, the apertures 304 or 306 may be arranged in an irregular arrangement, which may be called an irregular array. In an arrangement with a regular array, the conductive strips 322, 324 may be parallel to each other and perpendicular to the principle axis of the array. In the example shown in Figures 7 to 10, the apertures 304, 306 are arranged in a square array. The regular array may have one principle axis horizontal in the plane of the page and another principle axis perpendicular in the plane of the page. Therefore, the conductive strips 322 in Figures 7 and 9 are parallel to each other and perpendicular to the horizontal principle axis. The conductive strips 324 in Figures 8 and 10 are parallel to each other and perpendicular to the vertical principle axis.

[0061]

[0091] The conductive strips 322 and 324 may each have a minor axis and a major axis. In the examples of Figures 7 and 9, each minor axis is horizontal and each major axis is vertical. In the examples of Figures 8 and 10, each minor axis is vertical and each major axis is horizontal. The pitch of the conductive strips 322 and 324 parallel to the minor axes may be greater than the pitch of the array parallel to the minor axes. Thus, each vertical conductive strip may contain multiple rows of apertures 304 and 306, and / or each horizontal strip may contain multiple rows of apertures 304 and 306. This configuration provides a good balance between controllability and ease of manufacture. Alternatively, the pitch of the conductive strips 322 and 324 parallel to the minor axes may be equal to the pitch of the array parallel to the minor axes, which provides finer spatial control of the electric field.

[0062]

[0092] In one embodiment, the conductive strip 322 of the first electrode system 311 is not parallel to the conductive strip 324 of the second electrode system 322, for example, it is perpendicular. This configuration may be particularly preferred, for example, when the conductive strips 322 of the first electrode system 311 are parallel to each other and the conductive strips 324 of the second electrode system 312 are parallel to each other. For example, the first electrode system 311 may include conductive strips 322 as shown in Figure 7 or Figure 9, and the second electrode system 312 may include conductive strips 324 as shown in Figure 8 or Figure 10, and vice versa. Crossing the conductive strips 322 and 324 in different electrode systems 311 and 312 in this way results in a wide range of possible combinations of potential differences between the corresponding apertures 304 and 306 in the first aperture body 301 and the second aperture body 302 without making the routing of electrical connections to each conductive strip 322 and 324 more difficult.

[0063]

[0093] In a further configuration, as illustrated in Figure 11, the multiple electrodes include multiple conductive elements 326 that fill each other without gaps. In the illustrated example, the conductive elements 326 are square. Other gap-filling shapes may be used. This method offers greater flexibility in manipulating charged particles compared to the conductive strip configuration described above with reference to Figures 7-10, but the routing of electrical signals to individual electrodes can become more complex.

[0064]

[0094] In a further configuration, as illustrated in Figure 12, the multiple electrodes include multiple conductive elements 328, each comprising at least a portion of a concentric loop, such as at least a portion of a concentric ring, like a circular ring. This configuration allows for efficient correction of aberrations having the same or similar symmetry as the concentric loop. However, routing electrical signals to individual electrodes can be more complex than in the configurations using conductive strips described above, with reference to Figures 7-10.

[0065]

[0095] In some embodiments, the first electrode system 311 includes a plurality of electrodes, each connected to a group of aperture surrounding surfaces as described above with reference to Figures 7 to 12, and the second electrode system 312 includes a single electrode 319 as illustrated in Figure 13. The single electrode 319 is electrically connected to all of the aperture surrounding surfaces of the second aperture body 302. Thus, the aperture surrounding surfaces of the second aperture body 302 are maintained at the same potential. Alternatively, the first electrode system 311 includes a plurality of electrodes, each connected to a group of aperture surrounding surfaces as described above with reference to Figures 7 to 12, and the second electrode system 312 includes a plurality of electrodes, each electrically insulated from one another, and electrically connected to the aperture surrounding surfaces of different apertures among the plurality of apertures of the second aperture body 302, as illustrated in Figure 14.

[0066]

[0096] In some embodiments, the aperture assembly 370 is used in conjunction with a charged particle projector 230. The charged particle projector 230 may form part of a charged particle beam tool 40. The charged particle beam tool 40 may include any type of tool that uses a charged particle beam. The charged particle beam tool 40 and / or the projector 230 include a plurality of lenses. Each lens projects a respective sub-beam of charged particles. In the type of charged particle beam tool 40 shown in Figure 3 or Figure 4, the plurality of lenses may include a plurality of focusing lenses 116 or a plurality of objective lenses 118 of the projector 230. Other charged particle beam tools 40 may be provided with other plurality of lenses.

[0067]

[0097] In such embodiments, the aperture assembly 370 may be integrated with or directly adjacent to a plurality of lenses. In one embodiment, each lens includes a multi-electrode lens. In this case, the first aperture body 301 may include the first electrode of the multi-electrode lens. In the schematic structure shown in Figure 6, the first electrode of the multi-electrode lens may be the first support structure 361 of the first aperture body 301. The plurality of electrodes of the first electrode system 311 are electrically insulated from the first electrode of the multi-electrode lens. This may be achieved by providing an electrically insulating layer between the first electrode system 311 and the first support structure 361 (which acts as an electrode of the multi-electrode lens) in Figure 6. In one embodiment, the second aperture body 302 includes the second electrode of the multi-electrode lens. In the schematic structure shown in Figure 6, the second electrode of the multi-electrode lens may be the second support structure 362 of the second aperture body 302. Multiple electrodes of the second electrode system 312 are electrically insulated from the second electrode of the multi-electrode lens. The first electrode system 311, the second electrode system 312, or both may have a voltage source connection. The voltage source connection may be configured to apply a potential difference to the aperture surface of at least one of the first and second aperture bodies 301, 302.

[0068]

[0098] The aperture assembly 370 may include a plurality of objective lenses 118, which are integrated with or directly adjacent to the aperture assembly 370. The objective lenses 118 may be configured in any of the embodiments described above with reference to Figures 3 and 4. Alternatively or in addition, the aperture assembly 370 may include a plurality of focusing lenses 116, which are integrated with or directly adjacent to the aperture assembly 370. Alternatively or in addition, the aperture assembly 370 is provided in or directly adjacent to an intermediate image plane 120 which includes an intermediate focal point 115 of the subbeam focused by the focusing lenses 116. The focusing lenses 116 may be configured in any of the embodiments described above with reference to Figures 3 and 4.

[0069]

[0099] The first electrode system 311 and the second electrode system 312 may be configured to introduce disturbance (sometimes called a disturbance field) into the global focusing field provided by the first and second electrodes of each of the multi-element lenses (and other electrodes of the multi-element lens). The first electrode system 311 and the second electrode system 312 may be focused by, for example, local correction. Thus, with respect to this type of embodiment, the first electrode system 311 and the second electrode system 312 may be called a disturbance electrode system, a disturbance electrode array, or a local focus correction electrode. The local correction for focusing may differ between different subbeams passing through the manipulator unit. The local correction for focusing may involve a potential difference between different electrodes of the first electrode system 311 or between different electrodes of the second electrode system 312, and this potential difference is small compared to the mean overall potential difference between the first and second electrodes of the multi-element lens. The electric drive unit 320 may be configured to control the potentials of the electrodes of the first electrode system 311 and / or the second electrode system 312 to achieve this. The electric drive unit 320 may be connectable to a voltage source connection. This control may be such that the potential difference between the highest potential electrode and the lowest potential electrode of the first electrode system 311 is less than the difference between the average potential of the electrodes of the first electrode system 311 and the average potential of the electrodes of the second electrode system 312 (optionally less than 50%, optionally less than 10%, optionally less than 5%, optionally less than 1%, optionally less than 0.1%). In one particular embodiment, for example, the first electrode of the multi-electrode lens (which has a potential equal to or close to the average potential of the electrodes of the first electrode system 311) is supplied at 30kV, and the second electrode of the multi-electrode lens (which has a potential equal to or close to the average potential of the electrodes of the second electrode system 312) is supplied at 2.5kV, with deviations from these potentials of about 100V provided by the electrodes of the first electrode system 311 and / or the second electrode system 312. The known formula f = 4*U beam / E local Based on the focal length given by (Ubeam E is the local energy of the charged particle beam. local (where is the local electric field strength), such a potential deviation is expected to result in a change in focal length of about 1 micron in a typical configuration containing electrons as charged particles. Therefore, this method can be used to provide macroscopic focus and / or leveling corrections. This correction can be used to correct focal plane deviations caused by, for example, one or more of the following: - Finite manufacturing tolerances: for example, control of the flatness (or curvature) and / or spacing between electrodes of the objective lens 118, - Mechanical mounting tolerances and deformations caused by the mechanical mounting of the objective lens 118, -Deformation caused by the force of an electrostatic field, -In embodiments without the collimator 525, image field curvature due to non-telecentric passage through the objective lens 118, - Image field curvature of the focusing lens 116 (because the beam is not parallelized as it passes through the focusing lens 116).

[0070]

[0100] The integration of the beam manipulator unit 300 can be carried out particularly efficiently using first and second electrode systems 311, 312 having intersecting conductive strips 322, 324 as described above. In the case of a two-electrode multi-electrode lens, a conductive strip 324 aligned along the X direction may be formed on the first electrode, and a conductive strip 322 aligned along the Y direction may be formed on the second electrode. The focal plane can then be corrected according to the function Δf = f(X) + f(Y), where f(X) and f(Y) represent focus corrections that can be applied as functions of X and Y, respectively. Focus correction is usually performed by providing a relatively stepwise increasing potential from one conductive strip to the next, while keeping the potential difference between adjacent conductive strips relatively small, while still providing a relatively large potential change over longer length scales. Feasible corrections that may be applied using the example geometry described above include corrections for some inclined planes, and higher-order corrections for curved surfaces (where the curves are aligned along the X or Y axis), or R 2 Dependency (however, R 2 =X 2 +Y 2 This includes a rotationally symmetric correction with ). This method can also be used with a multi-electrode lens configured to act as an Einzel lens.

[0071]

[0101] In one class of embodiments, as illustrated in Figures 15 to 17, each of at least a subset of apertures 304 within the first aperture body 301 consists of an elongated slit. Each elongated slit may be substantially linear. The elongated slit may have an aspect ratio less than 0.5. Thus, as shown in Figure 15, the ratio of the width 341 of the elongated slit to the length 342 of the elongated slit is less than 0.5. Furthermore, each corresponding aperture 306 within the second aperture body 302 consists of an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit. The first aperture body 301 may be located up-beam in the beam path of the second aperture body 302. The shape of the corresponding aperture 306 within the second aperture body may differ from the shape of the opening of the elongated slot within the first aperture body 301. Each of at least a subset of the openings may have a shape with substantially curved edges, such as one of the following: circular, oval, or elliptical. The longest axis of an elongated slit is the length of the elongated slit if the elongated slit is rectangular, and the major axis of the elongated slit if the elongated slit is oval or elliptical. The openings may have an aspect ratio, for example, between 0.5 and 1.0, optionally between 0.9 and 1.0, or optionally substantially equal to 1.0. Thus, an elongated slit in the first aperture body 301 may be aligned with an opening in the second aperture body 302 that is less elongated (i.e., has a smaller aspect ratio in the sense that its aspect ratio is closer to 1.0) or not elongated at all (e.g., a circular, oval, or elliptical opening with an aspect ratio close to 1.0). Alternatively, the opening in the second aperture body 302 may be elongated but not parallel to the elongated slit in the first aperture 301. This arrangement may be less desirable than having an opening with an aspect ratio closer to 1, because it can unnecessarily complicate the routing within the second aperture body 302 due to less space available for routing.The first aperture body 301, the second aperture body 302, or both may have a voltage source connection. The voltage source connection may be configured to have a potential difference applied to the aperture surrounding surface of at least one of the first and second aperture bodies 301 and 302.

[0072]

[0102] The effect of having an aperture 304 in a first aperture body 301, which is formed as an elongated slit, is to make the contribution of aperture 304 to the lensing effect asymmetric. This contribution is negligible in the direction parallel to the elongated slit and strong (compared to a circular aperture) in the direction perpendicular to the slit. The effect of a corresponding aperture in a second aperture body 302 (which has a different shape from the aperture in the corresponding aperture 304 in the first aperture body 301) is that in the direction parallel to the elongated slit, it produces a stronger lensing effect (compared to the elongated slit) with the opposite polarity, and in the direction perpendicular to the elongated slit, it produces a weaker or negligible lensing effect (compared to the elongated slit). As described above, the aperture in the second aperture body 302 is usually circular or nearly circular. However, the effect is stronger when the opening in the second aperture body 302 is elongated and not parallel to (e.g., perpendicular to) the elongated slit in the first aperture body 301. In the perpendicular case, for example, the contribution of the opening in the second aperture body 302 to the lens effect is twice as strong in the direction parallel to the elongated slit in the first aperture body 301 compared to when the opening in the second aperture body 302 is circular, and negligible in the direction perpendicular to the elongated slit in the first aperture body 301.

[0073]

[0103] In one embodiment, the length 342 of each elongated slit in the first aperture body 301 is sufficiently large compared to the separation distance between the first aperture body 301 and the second aperture body 302 so that the ends of the elongated slits are shielded by the second aperture body 302 (i.e., there are virtually no ends for charged particles passing through the aperture assembly 370). The length of the elongated slits is typically at least twice, and optionally at least three times, the separation distance between the first aperture body 301 and the second aperture body 302.

[0074]

[0104] The separation distance between the first aperture body 301 and the second aperture body 302 is preferably greater than the width of each elongated slit (at least twice as large, and at least three times as large, optionally). This provides sufficient distance from the elongated slits so that the field becomes nearly uniform before reaching the second aperture body 302, despite the disturbance to the field caused by the elongated slits in the width direction of the elongated slits.

[0075]

[0105] It is also desirable that the separation distance between the first aperture body 301 and the second aperture body 302 be greater than (optionally at least twice, optionally at least three times) the maximum in-planar dimension (e.g., the diameter of a circular opening) of each aperture 306 within the second aperture body 302. This also provides sufficient distance from the apertures 306 so that the field becomes nearly uniform before reaching the first aperture body 301.

[0076]

[0106] The maximum in-plan dimension of each aperture 306 within the second aperture body 302 may be substantially equal to the minimum in-plan dimension (i.e., width) of the corresponding elongated slit within the first aperture body 301. This may be achieved by the apertures 306 within the second aperture body 302 having a different shape from the corresponding elongated slats within the first aperture body 301. This allows the apertures 306 to function efficiently while minimizing routing disruption within the second aperture body 302. Thanks to the increased space available for routing within the second aperture body 302, it is desirable to have more routing within the second aperture body 302 than in the first aperture body 301 (as will be further discussed below).

[0077]

[0107] As described above, the elongation of the slit leads to a lensing effect from the slit becoming smaller parallel to the length of the slit and larger perpendicular to it. This can produce a quadrupole effect. The quadrupole effect allows the manipulator unit 300 to act as a stigmeter to correct astigmatism. The magnitude and polarity of the quadrupole effect are determined by the potential difference between the respective apertures 304 and 306. The direction of the quadrupole effect is determined by the orientation of the slit. This provides a high degree of control over the stigmation effect applied to individual beams and minimizes the number of independent electrical connections required for the region where the stigmation effect is applied. The effect when the opening in the second aperture body 302 is circular is qualitatively shown in Figures 16 and 17.

[0078]

[0108] FIG. 16 is a side cross-sectional view along the X direction (i.e., parallel to the width of the elongated slit). At the upper part of the dashed-line region in FIG. 16, the potential difference (in the Z direction) between the first aperture body 301 and the second aperture body 302 causes a relatively strong positive lens effect in the vicinity of the aperture 304 within the first aperture body 301 in the X direction (parallel to the width 341 of the elongated slit). This relatively strong positive lens effect occurs due to the elongated shape. The focal length of an infinitely elongated lens (sometimes called a slit lens) is 2*U beam / E local given by. A negative lens effect in the X direction occurs in the vicinity of the corresponding aperture 306 within the second aperture body 302. However, this negative lens effect is smaller because the aperture 306 is not very elongated (or not elongated at all). The focal length of a completely circular negative lens (sometimes called an aperture lens) is -4*U beam / E local . The net result is a remaining positive lens effect in the X direction. The remaining positive lens effect may be quantified by referring to the corresponding focal length, which, when the elongated slit is sufficiently elongated, is approximately equal to 4*U beam / E local . Here, U beam is the local energy of the charged particle beam, and E local is the local electric field strength.

[0079]

[0109] Figure 17 is a side cross-sectional view along the Y direction (i.e., parallel to the length of the elongated slit). In this orientation, a very small (or negligible) positive lensing effect exists near each aperture 304 in the first aperture body 301 in the Y direction (parallel to the length 342 of the elongated slit). A negative lensing effect in the Y direction occurs near aperture 306 in the second aperture body 302. As shown in Figure 16, the intensity of this negative lensing effect in the Y direction is the same as or equal to the intensity of the negative lensing effect at aperture 306 in the X direction. The negative lensing effect in the Y direction is greater than the positive lensing effect in the Y direction from the corresponding aperture 304 in the first aperture body 301. The net result is the residual negative lensing effect in the Y direction, and the corresponding focal length is -4*U beam / E local It is almost equal to.

[0080]

[0110] In the alternative case where each opening in the second aperture body 302 is elongated and perpendicular to the corresponding elongated slit in the first aperture body 301, the contribution of each opening in the second aperture body 302 to the lens effect is twice as strong in the direction perpendicular to the elongation of the opening and negligible in the direction parallel to the elongation of the opening. The net result is a twice as strong astigmatism effect. 2*U beam / E local A residual positive lens effect is introduced in the X direction, with a corresponding focal length approximately equal to -2*U. beam / E local A residual negative lens effect, with a corresponding focal length approximately equal to that of the original, is introduced in the Y direction.

[0081]

[0111] Therefore, a residual positive lensing effect is introduced in the X direction, and a residual negative lensing effect is introduced in the Y direction, thereby constructing the aforementioned quadrupole effect.

[0082]

[0112] The potential difference between apertures 304 and 306 may be provided using either the first electrode system 311 or the second electrode system 312 described above with reference to Figures 5 to 14. The first or second electrode system 311, 312, or both, of each of the first or second aperture bodies 301, 302, or both, may be electrically connected via a voltage source connection. This includes the use of an electrode system that is not necessarily limited to providing potential to a group of electrodes. Embodiments using elongated slits may use an electrode system that allows for individual control of the potential difference for each elongated slit or for each corresponding opening facing an elongated slit. For example, in one configuration, the first aperture body 301 includes a first electrode system 311 for applying potential to the aperture-surrounding surface of each aperture 304 of the first aperture body 304. The first electrode system 311 includes a plurality of electrodes. Each electrode is electrically insulated from the other electrodes of the first electrode system 311 and electrically connected to the aperture surface of each different aperture of aperture 304 of the first aperture body 301. Alternatively, or in addition to this, the second aperture body 302 may include a second electrode system 312 for applying a potential to the aperture surface of each aperture 306 of the second aperture body 302. The second electrode system 312 may include multiple electrodes. Each electrode is electrically insulated from the other electrodes of the second electrode system 312 and electrically connected to the aperture surface of each different aperture of aperture 306 of the second aperture body 302. Thus, either or both of the first aperture body 301 and the second aperture body 302 may include an electrode system of the type shown in Figure 14. However, to avoid unnecessarily complex electrical routing requirements, typically only one of the two aperture bodies 301 and 302 contains the type of electrode system shown in Figure 14. For example, the type of electrode system shown in Figure 14 may be located within one of the two aperture bodies 301 and 302 that does not contain an elongated slit.This configuration can be preferable because an aperture body without an elongated slit may have a less elongated opening. The less elongated the opening, the more space may be available for routing electrical connections. However, as described above, any other combination of the disclosed first electrode system 311 and second electrode system 312 may be used. For example, a combination of the second electrode system 312 implemented as shown in Figure 12 and the first aperture system 311 implemented as shown in Figure 20 or Figure 21 may be particularly efficient.

[0083]

[0113] Instead of or in addition to the exemplary embodiments of the first electrode system 311 and the second electrode system 312 described above, the potential difference between apertures 304 and 306 may be provided using a local integrated electronic device. The local integrated electronic device may be implemented, for example, using CMOS technology. An example of a configuration using CMOS technology is shown in Figures 18 and 19. In this example, the second aperture body 302 includes a local integrated electronic device for each aperture 306 of the second aperture body 302. The local integrated electronic device is configured to apply a potential to the aperture surface of aperture 306. Instead of or in addition thereto, the first aperture body 301 may include a local integrated electronic device for each aperture 304 of the first aperture body 301, and the local integrated electronic device is configured to apply a potential to the aperture surface of aperture 304. A voltage source connection provides local integrated electronic equipment to the first or second aperture body 301, 302, or both. Alternatively, or in addition to this, the potential difference between apertures 304 and 306 may be provided using an integrated passive circuit. The integrated passive circuit may include a resistor network. The resistor network allows different potentials to be applied to the aperture periphery surfaces of at least a subset of apertures of the first aperture body by potential division. The resistor network may include resistors in series. The resistors in series may be selected to achieve a desired set of steps in the potential at the nodes between the resistors (as done with a voltage divider). The potential at the nodes is used to provide a desired range of potential differences between apertures 304 and 306. The resistor network may be integrated with either or both of the first aperture body 301 and the second aperture body 302. A voltage source connection is provided for a resistor network within the first or second aperture body 301, 302, or both. By providing the required potential difference using local integrated electronics and / or integrated passive circuits, advanced control is achieved and routing difficulties are reduced.However, the configuration of each first or second aperture body becomes more complex. Furthermore, the range of potential differences that can be applied by such integrated electronic equipment and / or integrated passive circuits may be narrower than the range of potential differences that can be applied using externally driven electrodes (for example, using an electrode system such as the one described herein).

[0084]

[0114] The direction of the quadrupole effect is determined by the orientation of the elongated slit. Therefore, the orientation of the elongated slit may vary depending on the expected symmetry of the aberration to be corrected.

[0085]

[0115] In one embodiment, as illustrated in Figure 20, at least the majority of the elongated slits (labeled as apertures 304) are aligned radially with respect to a common axis that passes perpendicularly through the plane of the first aperture body 311. (The common axis may be perpendicular to the plane of the page in the orientation of Figure 20.) The first aperture body 311, which may be a plate, may be planar in shape and have multiple apertures 304. In one configuration, the apertures defined by the first aperture body 311 are elongated slits. These slits may have a major axis and a minor axis and may be rectangular or elliptical. Rectangular slits may have a long side aligned with the major axis of the slit. Thus, the sides of a rectangular slit are aligned with the direction of each slit toward the common axis. The first aperture body 311 may have an axis that may correspond to the center of the first aperture body, as shown in Figure 20. This axis may be called, for example, a common axis with respect to the slit apertures 304. At least most, if not all, of the slit apertures are oriented relative to a common axis so that the long axis of each slit aperture aligns with the direction toward the common axis from the slit aperture. Slit apertures positioned on the reflection axis of the pattern of slit apertures defined within the first aperture body 311 are angularly similar along the reflection axis, only their position within the pattern is shifted. Such axes are, for example, the x and y axes, with a 45-degree angle between them. All other slit apertures are angularly shifted from one another and similarly shifted in position, but are aligned toward the common axis in the plane of the first aperture body 311.

[0086]

[0116] In one embodiment, as illustrated in Figure 21, at least the majority of the elongated slits (labeled aperture 304) are aligned substantially azimuthal with respect to the common axis, i.e., substantially perpendicular to the radial direction relative to the common axis. The arrangement of apertures 304 within the first aperture body 311 follows the same pattern as shown in Figure 311, but with an important difference. The alignment directions of the major and minor axes of each aperture are reversed, so that the minor axis of each aperture is aligned toward the common axis in the first aperture body 311, and the major axis is aligned perpendicular to the direction toward the common axis within the aperture pattern of the first aperture body 311. Apertures within the first aperture body 311 that are equidistant from the common axis are aligned tangentially with respect to their respective common radial displacements from the common axis. Thus, in the case of a rectangular slit, the major axis of the slit and the aligned sides of the slit are perpendicular to the direction toward the common axis from the slot.

[0087]

[0117] In one embodiment, as illustrated in Figures 22 and 23, at least the majority of the elongated slits are parallel to one another. The elongated slits may further be aligned within a plurality of rows traversing the first aperture body, preferably extending between the edges of the first aperture body 301. The rows may be linear, for example, in the transverse or longitudinal direction, or in the vertical or horizontal direction, within the first aperture body 311. The rows may be parallel to one another. The rows may or may not be parallel to the edges of the first aperture body 301.

[0088]

[0118] To provide more complete control of astigmatism, including control of the magnitude and direction of stigmation, an additional quadripolar effect, independently controllable and obliquely aligned, may be provided by an additional aperture body. Examples of such configurations are shown in Figures 24–26, where the elongated slit is rotated 45 degrees compared to the configurations in Figures 15–17. In this type of embodiment, a third aperture body 351 and a fourth aperture body 352 are provided. The third aperture body 351 may be configured in any of the embodiments described above for the first aperture body 301. The fourth aperture body 352 may be configured in any of the embodiments described above for the second aperture body 302. The potential difference between the third aperture body 351 and the fourth aperture body 352 may be controlled in any of the embodiments described above for the first aperture body 301 and the second aperture body 302 to control the additional quadripolar effect. Multiple apertures 354 within the third aperture body 351 are aligned with the corresponding multiple apertures 304, 306, and 356 within the first aperture body 301, the second aperture body 302, and the fourth aperture body 352. This alignment allows each of the multiple charged particle beams to pass through the aperture assembly by passing through the respective apertures 304, 306, 354, and 356 within each of the four bodies, for example, the first aperture body 301, the second aperture body 302, the third aperture body 351, and the fourth aperture body 352. Each of at least a subset of the apertures 354 within the third aperture body 351 consists of an elongated slit. Each corresponding aperture 356 within the fourth aperture body 352 consists of an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit. The elongated slit in the third aperture body 351 may be configured in any of the manner described above for the elongated slit in the first aperture body 301. The opening in the fourth aperture body 352 may be configured in any of the manner described above for the opening in the second aperture body 302.(For example, the opening in the fourth aperture body 352 may have a different shape from the corresponding elongated slot in the third aperture body 351.) The elongated slits in the first aperture body 301 and the third aperture body 351 are aligned so that each charged particle beam passes through the elongated slits in the first aperture body 301 and the third aperture body 351, which are aligned obliquely to each other when viewed along the path of the charged particle beam. In the particular example illustrated, the elongated slits are aligned at 45 degrees, but other oblique angles can also be selected. By controlling the quadrupole effect provided by the first and second aperture bodies 301, 302, as well as the obliquely aligned quadrupole effect provided by the third and fourth aperture bodies 351, 352, it becomes possible to control both the magnitude and direction of the overall quadrupole effect applied to each subbeam of charged particles. This provides a high degree of control without requiring an excessive number of independent electrical connections.

[0089]

[0119] In one embodiment, the charged particle beam tool 40 includes an electron detection device 240 that detects either or both secondary electrons and backscattered electrons from a sample. In the example shown in Figures 3 and 4, the electron detection device 240 is integrated with the objective lens 118. The electron detection device 240 may include, for example, a CMOS chip detector integrated with the bottom electrode of one or more of the lenses of the objective lens 118. Alternatively, a secondary optical column may be provided to direct secondary electrons and / or backscattered electrons to an electron detection device 240 located elsewhere. As described above, the electron detection device 240 may generate signals that are sent to the controller 50 or signal processing system as described above with reference to Figures 1 and 2, for example, to construct an image of the area of ​​the sample 208 scanned by the charged particle beam tool 40, or to perform other post-processing.

[0090]

[0120] In one embodiment, as illustrated in Figures 27 to 31 discussed below, the objective lens includes multiple electrodes, and the bottom electrode of this multi-electrode lens is integrated with a CMOS chip detector array. The multi-electrode lens may include three electrodes as illustrated in Figure 27, two electrodes as illustrated in Figure 28, or a different number of electrodes. Integrating the detector array with the objective lens eliminates the need for a secondary column for detecting secondary and backscattered electrons. The CMOS chip is preferably oriented to face the sample (because the distance between the wafer and the bottom of the electro-optical system is short (e.g., 100 μm)). In one embodiment, electrodes for capturing secondary electron signals are formed within the upper metal layer of the CMOS device. Electrodes may be formed in other layers. Power and control signals of the CMOS can be connected to the CMOS via through-silicon vias. For robustness, the bottom electrode preferably consists of two elements: the CMOS chip and a passive Si plate with holes. This plate shields the CMOS from high electric fields.

[0091]

[0121] To maximize detection efficiency, it is desirable to make the electrode surface as large as possible so that substantially the entire area of ​​the array objective lens (excluding the aperture) is occupied by the electrodes. Each electrode has a diameter substantially equal to the array pitch. In some embodiments, the electrode outline is circular, but this may be square to maximize the detection area. The diameter of the substrate through-holes can also be minimized. The typical size of the electron beam is about 5 to 15 microns.

[0092]

[0122] In one embodiment, a single electrode surrounds each aperture. In another embodiment, multiple electrode elements are provided around each aperture. Electrons captured by the electrode elements surrounding one aperture may be combined into a single signal or used to generate independent signals. The electrode elements may be divided radially (i.e., forming multiple concentric rings), angularly (i.e., forming multiple fan-shaped sections), both radially and angularly, or in any other convenient manner.

[0093]

[0123] However, increasing the electrode surface area leads to increased parasitic capacitance and, consequently, a decrease in bandwidth. Therefore, limiting the electrode's outer diameter is sometimes desirable, especially when increasing the electrode size provides only a slight improvement in detection efficiency but a significant increase in capacitance. Circular (annular) electrodes can offer a good compromise between collection efficiency and parasitic capacitance.

[0094]

[0124] Increasing the outer diameter of the electrode can also lead to an increase in crosstalk (sensitivity to signals from adjacent holes). This can be a reason to reduce the outer diameter of the electrode, especially if the enlargement of the electrode provides only a slight improvement in detection efficiency but results in a significant increase in crosstalk.

[0095]

[0125] The current of backscattered electrons and / or secondary electrons collected by the electrodes is amplified by a transimpedance amplifier.

[0096]

[0126] Exemplary embodiments are shown in Figures 27 and 28, which show a schematic cross-section of a multibeam objective lens 401. A detector module 402 is provided on the output side (the side facing the sample 403) of the objective lens 401. Figure 29 is a bottom view of the detector module 402, which includes a substrate 404 on which a plurality of capture electrodes 405 are provided, each capture electrode 405 surrounding a beam aperture 406. The beam aperture 406 can be formed by etching through the substrate 404. In the arrangement shown in Figure 29, the beam aperture 406 is shown as a rectangular array. The beam aperture 406 can also be arranged differently (for example, as a hexagonal close-packed array, as shown in Figure 30).

[0097]

[0127] Figure 31 shows a cross-sectional view of a portion of the detector module 402, scaled down. The capture electrode 405 forms the bottom surface of the detector module 402, i.e., the surface closest to the sample. A logic layer 407 is provided between the capture electrode 405 and the main body of the silicon substrate 404. The logic layer 407 may include an amplifier, such as a transimpedance amplifier, an analog-to-digital converter, and a readout logic circuit. In one embodiment, there is one amplifier and one analog-to-digital converter for each capture electrode 405. The logic layer 407 and the capture electrode 405 can be manufactured using a CMOS process in which the capture electrode 405 forms the final metallization layer.

[0098]

[0128] The wiring layer 408 is located on the underside of the substrate 404 and is connected to the logic layer 407 by through-silicon vias 409. The number of through-silicon vias 409 does not need to be the same as the number of beam apertures 406. Specifically, if electrode signals are digitized in the logic layer 407, only a small number of through-silicon vias may be required to provide a data bus. The wiring layer 408 may include control lines, data lines, and power lines. You will notice that there is enough space for all the necessary connections despite the beam apertures 406. The detection module 402 can also be fabricated using bipolar or other manufacturing techniques. A printed circuit board and / or other semiconductor chips may be located on the underside of the detector module 402.

[0099]

[0129] In embodiments in which the aperture assembly 370 is integrated with multiple objective lenses, the aperture assembly 370 can be integrated with the multibeam objective lens 401 shown in Figure 27 or Figure 28. In such a case, the first aperture body 301 includes one of the multiple electrodes of the multibeam objective lens shown in Figure 27 or Figure 28, and the second aperture body 302 includes one different electrode of the multibeam objective lens 401.

[0100]

[0130] Embodiments of this disclosure may be provided in the form of a method, which may use any or other configurations described above.

[0101]

[0131] In one class of embodiments, a method for manipulating charged particles, optionally for inspection, is provided, which includes directing a plurality of charged particle beams toward a sample 208 through an aperture assembly 370. The charged particle beams are manipulated electrostatically by applying a potential to electrodes within the aperture assembly. The aperture assembly 370 may take any of the forms described above. Thus, the aperture assembly 370 may include a first aperture body 301 and a second aperture body 302. A plurality of apertures 304 in the first aperture body 301 are aligned with a corresponding plurality of apertures 306 in the second aperture body 302, so that each of the charged particle beams passes through the aperture assembly 370 by passing through the respective apertures 304, 306 in the first aperture body 301 and the second aperture body 302. Applying a potential involves applying a potential to multiple electrodes, each of which is electrically insulated from one another and simultaneously electrically connected to the surrounding surface of different groups of apertures among multiple groups of apertures of the first aperture body 301.

[0102]

[0132] In another class of embodiments, a method for manipulating charged particles, optionally a method for inspection, is provided, which includes directing a plurality of charged particle beams toward a sample 208 through an aperture assembly. The charged particle beams are manipulated electrostatically by applying a potential to electrodes in the aperture assembly. The aperture assembly may take any of the forms described above. Thus, the aperture assembly may include a first aperture body 301 and a second aperture body 302. A plurality of apertures 304 in the first aperture body 301 are aligned with a corresponding plurality of apertures 306 in the second aperture body 302, so that each of the charged particle beams passes through the aperture assembly by passing through the respective apertures 304, 306 in the first aperture body 301 and the second aperture body 302. The shape of the apertures in the second aperture body may differ from the shape of the apertures in the first aperture body, which may be elongated. Applying a potential involves applying a potential difference between an aperture 304 in the first aperture body 301 and the corresponding aperture 306 in the second aperture body 302. Each of at least a subset of apertures 304 in the first aperture body 301 consists of an elongated slit. Each corresponding aperture 306 in the second aperture body 302 consists of an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit. The potential may be applied in a manner that reduces astigmatism in the charged particle beam.

[0103]

[0133] Adjacent electron-optical elements along the beam path may be structurally connected to each other using electrically insulating elements, such as spacers. These insulating elements may be made of electrically insulating materials such as ceramics or glass.

[0104]

[0134] References to a plurality of components or a plurality of components or a system that can be controlled to manipulate a charged particle beam in a particular manner include configuring a controller or control system or control unit to control the components for manipulating the charged particle beam in the manner described above, and optionally, to control the components for manipulating the charged particle beam in this manner using other controllers or devices (e.g., voltage sources and / or current sources), such as controller 50. For example, a voltage source or “drive unit” as referred herein may be electrically connected to one or more components to apply a potential to the components, e.g., objective lens array 118, focusing lens 231, compensators 124, 125, and 126, collimator element array 524, etc., under the control of the controller or control system or control unit. An operable component, such as a stage, may be controlled to be actuated and thus moved relative to another component, such as a beampath, using one or more controllers, control systems, or control units to control the operation of that component.

[0105]

[0135] Embodiments described herein may take the form of a series of aperture arrays or electron-optical elements arranged in an array along a single-beam or multi-beam path. Such electron-optical elements may be electrostatic. In one embodiment, for example, all electron-optical elements in the sub-beam path prior to the sample, from the beam-limiting aperture array to the last electron-optical element, may be electrostatic and / or in the form of an aperture array or plate array. Depending on the configuration, one or more of the electron-optical elements may be manufactured as a micro-electromechanical system (MEMS) (i.e., using MEMS manufacturing techniques).

[0106]

[0136] References to "upper" and "lower," "up" and "down," and "upward" and "downward" should be understood to refer to directions parallel to the (usually, but not always, perpendicular) up-beam and down-beam directions of the electron beam or multibeam corresponding to Sample 208. Therefore, references to up-beam and down-beam are intended to refer to directions related to the beam path, independently of any gravitational field.

[0107]

[0137] Embodiments can be further described using the following clauses. 1. An aperture assembly for a beam manipulator unit of a charged particle projection device, It includes a first aperture body and a second aperture body, Multiple apertures within the first aperture body are aligned with corresponding multiple apertures within the second aperture body, and the alignment is such that each path of each of the multiple charged particle beams passes through the aperture assembly by passing through the respective apertures within the first and second aperture bodies. The first aperture body includes a first electrode system for applying a potential to the surface surrounding each aperture within the first aperture body. The second aperture body includes a second electrode system for applying a potential to the surface surrounding each aperture within the second aperture body. An aperture assembly comprising a first electrode system including multiple electrodes, each electrode electrically insulated from the other electrodes, and simultaneously electrically connected to the surrounding surface of different groups of apertures among multiple groups of apertures within a first aperture body. 2. An assembly as described in Clause 1, wherein at least two of the groups of apertures contain the same number of apertures. 3. Each electrode of the first electrode system is an assembly according to clause 1 or 2, including an elongated conductive strip. 4. The assembly according to Clause 3, wherein the apertures within the first aperture body are arranged in an array, preferably in a regular array. 5. The assembly described in Clause 4, wherein the conductive strips are parallel to each other and perpendicular to the principle axis of the array. 6. The assembly described in Clause 5, in which the pitch of conductive strips parallel to the minor axis of the conductive strips is greater than the pitch of the array parallel to the minor axis. 7. The assembly described in Clause 5, where the pitch of conductive strips parallel to the minor axis of the conductive strips is equal to the pitch of the array parallel to the minor axis. 8. An assembly according to any one of the preceding clauses, comprising multiple electrodes and multiple conductive elements configured to fill each other without any gaps. 9. The assembly according to Clause 1 or 2, comprising a plurality of conductive elements including at least a portion of a concentric loop. 10. The second electrode system is the assembly described in any of the preceding clauses, comprising electrodes electrically connected to all of the surrounding surfaces of the second aperture body. 11. The assembly according to any one of claims 1 to 9, wherein the second electrode system comprises a plurality of electrodes, each electrode being electrically insulated from the other electrodes and simultaneously electrically connected to the surrounding surface of apertures of different groups of a plurality of groups of apertures of the second electrode system. 12. Each electrode of the first electrode system includes an elongated conductive strip, Each electrode in the second electrode system includes an elongated conductive strip. The conductive strip of the first electrode system is not parallel to the conductive strip of the second electrode system, as described in Clause 11. 13. The assembly according to Clause 12, wherein the conductive strips of the first electrode system are parallel to each other, the conductive strips of the second electrode system are parallel to each other, and the conductive strips of the first electrode system are perpendicular to the conductive strips of the second electrode system. 14. The assembly according to any one of the preceding clauses, wherein the aperture in the first aperture body and / or the aperture in the second aperture body have a curved edge shape, preferably a circular, elliptical, or egg-shaped shape. 15. Each of at least a subset of apertures within the first aperture body consists of an elongated slit. The assembly described in any one of the preceding clauses, wherein each corresponding aperture in the second aperture body consists of an opening smaller than the elongated slit in at least a direction parallel to the longest axis of the elongated slit. 16. Aperture assembly for a beam manipulator unit of a charged particle projection apparatus, It includes a first aperture body and a second aperture body, Multiple apertures within the first aperture body are aligned with corresponding multiple apertures within the second aperture body, and the alignment is such that each path of each of the multiple charged particle beams passes through the aperture assembly by passing through the respective apertures within the first and second aperture bodies. Each of at least a subset of apertures within the first aperture body consists of an elongated slit. An aperture assembly in which each corresponding aperture within a second aperture body consists of an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit. 16a. The aperture assembly according to clause 16, comprising a voltage source connection configured to apply a potential difference to the peripheral surface of at least one of the first and second aperture bodies. 16b. The aperture assembly according to clause 16 or 16a, wherein each corresponding aperture in the second aperture body consists of an opening having a different shape from the corresponding elongated slit. 16c. Aperture assembly for an aberration corrector for a beam manipulator unit of a charged particle projection apparatus, comprising a first aperture body and a second aperture body, wherein the first aperture body is configured to be an up-beam of the second aperture body along the path of the charged particles, and a plurality of apertures in the first aperture body are aligned with a corresponding plurality of apertures in the second aperture body, and this alignment is achieved by passing each path of each plurality of charged particle beams through the aperture assembly by passing through the respective apertures in the first aperture body and the second aperture body. An aperture assembly comprising: a second aperture body, which allows for the passage of light, wherein each of at least a subset of apertures in a first aperture body consists of an elongated slit, and each corresponding aperture in a second aperture body consists of an opening which has a different shape from the corresponding elongated slit and is smaller than the corresponding elongated slit at least in a direction parallel to the longest axis of the elongated slit; and a voltage source connection configured to apply a potential difference to the aperture surrounding surface of at least one of the apertures in the first and second aperture bodies. 17. The first aperture body includes a first electrode system for applying a potential to the aperture periphery surface of each aperture of the first aperture body, the first electrode system preferably being associated with and electrically connected to a voltage source connection, the first electrode system including a plurality of electrodes, each electrode being electrically insulated from the other electrodes of the first electrode system and electrically connected to the aperture periphery surface of each different aperture of the plurality of apertures of the first aperture body, and / or The assembly according to any one of the clauses 16 to 16c, wherein the second aperture body includes a second electrode system for applying a potential to the aperture periphery surface of each aperture of the second aperture body, the second electrode system preferably being associated with and electrically connected to a voltage source connection, the second electrode system including a plurality of electrodes, each electrode being electrically insulated from each other from other electrodes of the second electrode system and electrically connected to the aperture periphery surface of each different aperture of the plurality of apertures of the second aperture body. 18. The first aperture body includes a local integrated electronic device for each aperture of the first aperture body, the local integrated electronic device being configured to apply a potential to the aperture surface of the aperture, the local integrated electronic device being preferably associated with and electrically connected to a voltage source connection, and / or The assembly according to any one of clauses 16 to 16c, wherein the second aperture body includes a local integrated electronic device for each aperture of the second aperture body, the local integrated electronic device being configured to apply a potential to the aperture-surrounding surface of the aperture, and the local integrated electronic device is preferably associated with and electrically connected to a voltage source connection. 19. The first aperture body includes an integrated passive circuit including a resistor network, which is configured to apply different potentials to the aperture periphery surfaces of at least a subset of the apertures of the first aperture body by potential division, and the resistor network is preferably associated with and electrically connected to a voltage source connection, and / or The assembly according to any one of clauses 16 to 16c or 18, wherein the second aperture body includes an integrated passive circuit including a resistor network, which is configured to apply different potentials to the aperture periphery surfaces of at least a subset of the apertures of the second aperture body by potential division, and the resistor network is preferably associated with and electrically connected to a voltage source connection. 20. An assembly as described in any one of clauses 15 to 19, wherein each of at least a subset of the elongated slits is substantially a straight slit. 21. The assembly according to any one of the clauses 15 to 20, wherein each of at least a subset of the openings is preferably shaped with a curved edge, such as one of substantially circular, oval, or elliptical shapes. 22. The assembly according to any one of clauses 15 to 21, wherein at least the majority of the elongated slits are aligned radially with respect to a common axis passing perpendicularly through the plane of the first aperture body. 23. The assembly according to any one of clauses 15 to 22, wherein at least the majority of the elongated slits are aligned perpendicular to the radial direction with respect to a common axis passing perpendicularly through the plane of the first aperture body. 24. An assembly as described in any one of clauses 15 to 23, wherein at least the majority of the elongated slits are parallel to one another. 25. An assembly as described in any one of clauses 15 to 24, wherein the maximum in-plan dimension of each opening in the first aperture body is substantially equal to the minimum in-plan dimension of the corresponding elongated slit in the second aperture body. 25a. An assembly as described in any one of clauses 15 to 24, wherein the maximum in-plan dimension of each opening in the second aperture body is substantially equal to the minimum in-plan dimension of the corresponding elongated slit in the first aperture body. 26. The aperture assembly further includes a third aperture body and a fourth aperture body, Multiple apertures within the third aperture body are aligned with corresponding multiple apertures within the first, second, and fourth aperture bodies, and the alignment is such that each path of each of the multiple charged particle beams passes through the aperture assembly by passing through the respective apertures within the first, second, third, and fourth aperture bodies. Each of at least a subset of apertures within the third aperture body consists of an elongated slit. Each corresponding aperture within the fourth aperture body consists of an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit. The assembly according to any one of clauses 15 to 25a, wherein the elongated slits in the first aperture body and the third aperture body are aligned such that each charged particle beam passes through the elongated slits in the first aperture body and the third aperture body, which are aligned obliquely to each other when viewed along the path of the charged particle beam. 27. A beam manipulator unit for a charged particle projection device, The aperture assembly of any one of the preceding clauses, A beam manipulator unit comprising: an electrically driven unit, preferably connected to a voltage source connection, configured to apply a potential to the aperture-surrounding surface of apertures in a first aperture body and / or a second aperture body while a plurality of charged particle beams are directed through an aperture assembly towards a sample. 28. A charged particle projection device, The beam manipulator unit described in Article 27, A charged particle projection apparatus comprising a plurality of lenses, each lens configured to project a respective subbeam of charged particles. 29. The apparatus according to Clause 28, wherein the aperture assembly is integrated with or directly adjacent to a plurality of lenses, preferably the direct adjacency includes the immediate up beam or down beam of the plurality of lenses. 30. Each lens includes a multi-electrode lens. The first aperture body includes the first electrode of the multi-electrode lens, The apparatus according to Clause 29, wherein the first aperture body includes a first electrode system comprising a plurality of electrodes electrically insulated from the first electrode of a multi-electrode lens. 31. The second aperture body includes the second electrode of the multi-electrode lens. The apparatus according to Clause 30, wherein the second aperture body includes a second electrode system comprising a plurality of electrodes electrically insulated from the second electrode of the multi-electrode lens. 32. The apparatus according to Clause 30 or 31, wherein the electric drive unit is configured to control the potential of the electrodes of the first electrode system such that the potential difference between the highest potential electrode and the lowest potential electrode of the first electrode system is less than the difference between the average potential of the electrodes of the first electrode system and the average potential of the electrodes of the second electrode system. 33. The apparatus described in any one of clauses 28 to 32, comprising multiple objective lenses configured to project their respective sub-beams onto a sample. 34. The apparatus according to any one of clauses 28 to 32, wherein the multiple lenses include multiple focusing lenses configured to focus each sub-beam from multiple objective lenses configured to project a sub-beam onto a sample to an intermediate focal point in the up-beam. 35. The apparatus includes a plurality of focusing lenses configured to focus each subbeam to an intermediate focal point in the intermediate image plane, The apparatus according to any one of Clauses 28 to 32, wherein the aperture assembly is provided in the intermediate image plane or directly adjacent to the intermediate image plane, preferably the direct adjacent includes the up beam or down beam, or both, immediately adjacent to the intermediate image plane. 36. A charged particle beam tool, A charged particle projection device as described in any one of Articles 28 to 35, A charged particle beam tool comprising an electron detection device configured to detect either or both secondary electrons and backscattered electrons from a sample. 37. A method for manipulating a charged particle beam, Directing multiple charged particle beams towards the sample through an aperture assembly, This includes electrostatically manipulating a charged particle beam by applying an electric potential to electrodes within an aperture assembly, The aperture assembly includes a first aperture body and a second aperture body. Multiple apertures within the first aperture body are aligned with corresponding multiple apertures within the second aperture body, so that each charged particle beam passes through the aperture assembly by passing through its respective aperture within the first and second aperture bodies. A method for applying a potential, comprising applying a potential to a plurality of electrodes, each of which is electrically insulated from one another and simultaneously electrically connected to the surrounding surface of different groups of apertures among a plurality of groups of apertures of a first aperture body. 38. A method for manipulating a charged particle beam, Directing multiple charged particle beams towards the sample through an aperture assembly, This includes electrostatically manipulating a charged particle beam by applying an electric potential to electrodes within an aperture assembly, The aperture assembly includes a first aperture body and a second aperture body. Multiple apertures within the first aperture body are aligned with corresponding multiple apertures within the second aperture body, so that each charged particle beam passes through the aperture assembly by passing through its respective aperture within the first and second aperture bodies. Applying an electric potential involves applying a potential difference between the aperture in the first aperture body and the corresponding aperture in the second aperture body. Each of at least a subset of apertures within the first aperture body consists of an elongated slit. A method wherein each corresponding aperture in the second aperture body consists of an opening smaller than the elongated slit, at least in a direction parallel to the longest axis of the elongated slit. 39. The method according to clause 38, wherein the potential is applied in such a manner that it reduces astigmatism in a charged particle beam. 40. An aperture assembly for a manipulator unit of a charged particle multibeam projection apparatus, A first aperture body that defines a first array of apertures, A second aperture body defines a corresponding array of apertures that are aligned with a first array of apertures to define the path of each charged particle beam of a multibeam passing through the aperture assembly, A first electrode system associated with the first aperture body, configured to apply an electric potential to the surrounding surface of each aperture of the first aperture body, The second electrode system is associated with the second aperture body and is configured to apply a potential to the surrounding surface of each aperture of the second aperture body. An aperture assembly comprising a first electrode system including multiple electrodes, each electrode electrically insulated from the other electrodes, and simultaneously electrically connected to the circumferential surface of different groups of multiple groups of apertures of a first aperture body. 41. An aperture assembly for a beam manipulator unit of a charged particle multibeam projection system, A first aperture body that defines a first set of apertures, A second aperture body that defines a plurality of corresponding apertures positioned relative to a plurality of first apertures to define the path of each charged particle beam of a multibeam through an aperture assembly, Each of at least a subset of apertures within the first aperture body is an elongated slit, An aperture assembly in which each corresponding aperture in a set of multiple apertures corresponding to an elongated slit is an opening with an aspect ratio smaller than that of the elongated slit. 42. A beam manipulator unit for a charged particle multibeam projection apparatus, comprising a lens, the lens being: An up-beam lens aperture array having an associated up-beam disturbance electrode array, A downbeam lens aperture array having an associated downbeam disturbance electrode array, The up-beam lens aperture array, down-beam lens aperture array, and disturbance array are positioned relative to each other such that the apertures within each array define the path of each charged particle beam of the multibeam passing through the manipulator unit. Up-beam and down-beam disturbance electrodes are controllable to add a disturbance field to the field generated by the lens during operation, as part of a beam manipulator unit. 43. A method for manipulating a charged particle beam, To provide a lens including an up-beam lens aperture array having an associated up-beam disturbance electrode array and a down-beam lens aperture array having an associated down-beam disturbance electrode array, Passing multiple charged particle beams through their respective apertures within the up-beam lens aperture array and the down-beam lens aperture array, A method comprising controlling up-beam and down-beam disturbance electrodes so as to add a disturbance field to a field generated by a lens.

[0108]

[0138] Any of the charged particle beam tools 40 considered herein may be evaluation tools. An evaluation tool according to one embodiment of this disclosure may be a tool for qualitative evaluation of a sample (e.g., pass / fail), a tool for quantitative measurement of a sample (e.g., feature size), or a tool for generating an image of a map of a sample. Examples of evaluation tools include inspection tools (e.g., for identifying defects), review tools (e.g., for classifying defects), and measurement tools, or tools that can perform any combination of evaluation functions related to inspection tools, review tools, or measurement tools (e.g., measurement inspection tools). The electron-optical column 40 may be a component of an evaluation tool, such as an inspection tool or measurement inspection tool, or part of an electron beam lithography tool. References to tools herein are intended to encompass devices, apparatus, or systems, and a tool includes various components that may or may not be located in the same place, and in particular, data processing elements may even be located in separate rooms.

[0109]

[0139] The terms “subbeam” and “beamlet” are used interchangeably herein and are both understood to encompass any radiation beam derived from a parent radiation beam by splitting or splitting the parent radiation beam. The term “manipulator” is used to encompass any element that influences the path of a subbeam or beamlet, such as a lens or deflector.

[0110]

[0140] While the present invention has been described in relation to various embodiments, other embodiments will be apparent to those skilled in the art from considering the details and practices of the invention disclosed herein. This specification and examples are intended to be merely illustrative, and the true scope and spirit of the invention are shown in the following claims.

[0111]

[0141] The above description is intended to be illustrative and not limiting. It will therefore be apparent to those skilled in the art that modifications can be made as described without departing from the claims set forth below.

Claims

1. An aperture assembly for a beam manipulator unit of a charged particle projection device, It includes a first aperture body and a second aperture body, The plurality of apertures in the first aperture body are aligned with the corresponding plurality of apertures in the second aperture body, and the alignment is such that each path of the plurality of charged particle beams passes through the aperture assembly by passing through the respective apertures in the first aperture body and the second aperture body. The first aperture body includes a first electrode system for applying a potential to the surface surrounding each aperture within the first aperture body. The second aperture body includes a second electrode system for applying a potential to the surrounding surface of each aperture within the second aperture body. The first electrode system described above includes a plurality of electrodes, each electrode being electrically insulated from the other electrodes. Each electrode of the first electrode system includes an elongated conductive strip, The apertures within the first aperture body are arranged in an array. The elongated conductive strips are parallel to each other and perpendicular to the principle axis of the array. An aperture assembly in which the pitch of the elongated conductive strips parallel to the short axis of the elongated conductive strips is greater than the pitch of the array parallel to the short axis.

2. The assembly according to claim 1, wherein at least two of the plurality of groups of apertures in the first aperture body include the same number of apertures.

3. The assembly according to claim 1 or 2, wherein the second electrode system includes electrodes electrically connected to all of the surrounding surfaces of the second aperture body.

4. The assembly according to claim 1 or 2, wherein the second electrode system includes a plurality of electrodes, each electrode being electrically insulated from the other electrodes.

5. Each electrode of the second electrode system includes an elongated conductive strip, The assembly according to claim 4, wherein the elongated conductive strip of the first electrode system is not parallel to the elongated conductive strip of the second electrode system.

6. The assembly according to claim 1 or 2, wherein the aperture in the first aperture body and / or the aperture in the second aperture body have a shape having a curved edge.

7. Each aperture in at least one subset of the plurality of subsets of apertures within the first aperture body consists of an elongated slit. The assembly according to claim 1 or 2, wherein each corresponding aperture in the second aperture body has an opening smaller than the elongated slit in a direction parallel to the longest axis of the elongated slit.

8. A beam manipulator unit for a charged particle projection device, The aperture assembly according to claim 1 or 2, An electrically driven unit configured to apply a potential to the surface surrounding the aperture of the aperture in the first aperture body and / or the second aperture body while a plurality of charged particle beams are directed towards the sample through the aperture assembly, A beam manipulator unit comprising multiple lenses, each lens configured to project a respective subbeam of charged particles.

9. The beam manipulator unit according to claim 8, wherein the plurality of lenses include a plurality of objective lenses configured to project their respective sub-beams onto a sample.

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