Charged-particle optical module

Abstract

A charged particle optics module 200 for a charged particle optics device configured to guide a beam of charged particles toward a sample location along a beam path, the charged particle optics module comprising: an emitter 21 configured to emit a source beam of charged particles along a source path; a plurality of charged particle optics plate elements 24-26 configured to operate on the source beam, wherein each charged particle optics plate element defines: a beam aperture 266 configured for the passage of the source beam; a vent 46 configured to provide gas flow through the charged particle optics plate element to maintain a vacuum within the charged particle optics module; and a vacuum chamber in which the emitter and the plurality of charged particle optics plate elements are located, the vacuum chamber being configured to maintain a pressurized source in use.

Description

Cross-references to related applications

[0001] This application claims priority to European Patent Application 24167273.2, filed on 28 March 2024, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to a charged particle optical module, a charged particle optical device, an evaluation device, and a method for manufacturing a charged particle optical module. Background Technology

[0003] In manufacturing processes such as those for semiconductor integrated circuit (IC) chips or displays, undesirable defects may occur on the substrate (e.g., wafer) or mask. Such defects can reduce yield. Defects can occur as a result of various processes necessary for producing integrated circuits or displays, such as photolithography, etching, deposition, or chemical mechanical polishing. Defects may include patterning defects, where the created pattern exceeds the pattern tolerances for the process, and graininess. Therefore, the extent to which defects are monitored during the manufacturing process is important. Such monitoring (or more generally, evaluation) includes determining the presence of defects and classifying the types of defects found.

[0004] For sample evaluation, various types of inspection or measurement systems have been used, including charged particle systems such as electron microscopes. Such evaluations for inspection can involve defects, such as their presence and classification. Electron microscopes typically generate a probe beam (also often called a primary beam), which can, for example, be scanned across a portion of a substrate (as in scanning electron microscopy (SEM)). The interaction products resulting from the interaction of the primary beam with the portion of the substrate are collected, allowing the electron microscope to collect data representing the probed portion of the substrate. This data can, for example, be processed / rendered by the electron microscope to generate an image representation of that portion of the substrate. The collected data, for example, as the generated image representation, allows for the measurement of structures on the portion of the substrate, or allows for the identification of defective structures by comparing the image representation with a reference. Such measurements can be called metrology; such defect inspections can be called inspections. The interaction products can contain charged particles, such as secondary electrons and backscattered electrons, which may be called signal particles (e.g., signal electrons), and can also contain other interaction products, such as X-ray radiation.

[0005] The primary beam can be obtained from the source beam emitted by the source. Maintaining a sufficiently low pressure for the source can be difficult, for example, due to a lack of space for equipment capable of maintaining low pressure. It is desirable to make maintaining a sufficiently low pressure easier. Summary of the Invention

[0006] According to one aspect of the invention, a charged particle optical module for a charged particle optical device is provided, the charged particle optical device being configured to guide a beam of charged particles toward a sample location along a beam path. The charged particle optical module includes: an emitter configured to emit a source beam of charged particles along a source path; a plurality of charged particle optical plate elements configured to operate on the source beam, wherein each charged particle optical plate element defines: a beam aperture configured for the passage of the source beam; a vent configured to provide gas flow through the charged particle optical plate element to maintain a vacuum within the charged particle optical module; and a vacuum chamber in which the emitter and the plurality of charged particle optical plate elements are located, the vacuum chamber being configured to maintain a source under pressure during use.

[0007] According to another aspect of the invention, a charged particle optical module for a plurality of charged particle optical devices is provided, the plurality of charged particle optical devices being configured to guide a charged particle beam toward a sample location along a beam path. The charged particle optical module includes: a substrate element including a plurality of emitters configured to emit source beams of corresponding charged particles along respective source paths; and at least one charged particle optical plate element configured to operate on the source beam, wherein a plurality of beam apertures are defined, the beam apertures being configured to allow passage of the source beam, wherein a vent is defined in the substrate element and / or the at least one charged particle optical plate element, the vent being configured to provide gas flow through the element to maintain a vacuum within the charged particle optical module; and a vacuum chamber in which the emitters and at least one charged particle optical plate element are located, the vacuum chamber being configured to maintain a pressurized source in use.

[0008] According to another aspect of the invention, a charged particle optical module for a charged particle optical device is provided, the charged particle optical device being configured to guide a beam of charged particles toward a sample location along a beam path, the charged particle optical module comprising: an emitter configured to emit a source beam of charged particles along a source path; a plurality of charged particle optical plate elements configured to operate on the source beam, wherein each charged particle optical plate element defines a beam aperture configured for the passage of the source beam; a vacuum chamber in which the emitter and the plurality of charged particle optical plate elements are located, the vacuum chamber being configured to maintain a pressurized source in use; and a pump configured to remove gas from the vacuum chamber to maintain a pressurized source within the vacuum chamber in use, wherein the pump is located in the direction upstream of the beam from the emitter.

[0009] According to another aspect of the invention, a charged particle optical module for a plurality of charged particle optical devices is provided, the plurality of charged particle optical devices being configured to guide a charged particle beam toward a sample location along a beam path. The charged particle optical module includes: a substrate element including a plurality of emitters configured to emit source beams of corresponding charged particles along respective source paths; and at least one charged particle optical plate element configured to operate on the source beam, wherein a plurality of beam apertures are defined, the beam apertures being configured to allow passage of the source beam; a vacuum chamber in which the emitters and at least one charged particle optical plate element are located, the vacuum chamber being configured to maintain a pressurized source in use; and a pump configured to remove gas from the vacuum chamber to maintain a pressurized source within the vacuum chamber in use, wherein the pump is located in the direction upstream of the beam from the emitter.

[0010] According to another aspect of the invention, a method is provided for manufacturing a charged particle optical module for a charged particle optical device configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: providing an emitter configured to emit a source beam of charged particles along a source path; defining in each of a plurality of charged particle optical plate elements configured to operate on the source beam: a beam aperture for the passage of the source beam; and a vent configured to provide a gas flow through the charged particle optical plate element to maintain a vacuum within the charged particle optical module; and placing the emitter and the plurality of charged particle optical plate elements in a vacuum chamber configured to maintain a pressurized source in use.

[0011] According to another aspect of the invention, a method is provided for manufacturing a charged particle optical module for a plurality of charged particle optical devices configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: providing a substrate element including a plurality of emitters configured to emit source beams of corresponding charged particles along a respective source path; defining a plurality of beam apertures in at least one charged particle optical plate element configured to operate on the source beams, the beam apertures being configured to allow passage of the source beams; defining a vent in the substrate element and / or at least one charged particle optical plate element, the vent being configured to provide gas flow through the element to maintain a vacuum within the charged particle optical module; and placing the emitters and at least one charged particle optical plate element in a vacuum chamber configured to maintain a pressurized source in use.

[0012] According to another aspect of the invention, a method is provided for manufacturing a charged particle optical module for a charged particle optical device configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: providing an emitter configured to emit a source beam of charged particles along a source path; defining a beam aperture for the passage of the source beam in each of a plurality of charged particle optical plate elements configured to operate on the source beam; placing the emitter and the plurality of charged particle optical plate elements in a vacuum chamber configured to maintain a pressurized source in use; and arranging a pump in a direction upstream of the beam from the emitter, the pump being configured to remove gas from the vacuum chamber to maintain a pressurized source within the vacuum chamber in use.

[0013] According to another aspect of the invention, a method is provided for manufacturing a charged particle optical module for a plurality of charged particle optical devices configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: providing a substrate element including a plurality of emitters configured to emit source beams of corresponding charged particles along a respective source path; defining a plurality of beam apertures in at least one charged particle optical plate element configured to operate on the source beams, the beam apertures being configured to allow passage of the source beams; placing the emitters and at least one charged particle optical plate element in a vacuum chamber configured to maintain a pressurized source in use; and arranging a pump upstream of the beam from the emitters, the pump being configured to remove gas from the vacuum chamber to maintain a pressurized source within the vacuum chamber in use. Attached Figure Description

[0014] Embodiments of the invention will now be described by way of example only with reference to the accompanying illustrative drawings, in which: Figure 1 This is a schematic diagram of an exemplary evaluation device; Figure 2 A schematic depiction of a multi-beam charged particle optical device, such as... Figure 1 The evaluation device is a multi-beam charged particle optical instrument; Figure 3 An array of charged particle optical devices is schematically depicted. Figure 4 A charged particle optical module for at least one charged particle optical device is schematically depicted. Figure 5 A vacuum chamber is schematically depicted; Figure 6 An optical device for charged particles is schematically depicted. Figure 7 A charged particle optical module comprising multiple sources is schematically depicted. Figure 8 schematically depicted Figure 7 A plan view of the stacked charged particle optical modules shown. Figure 9 schematically depicted Figure 8 The side view of the stack shown; Figure 10 A source for an optical device for charged particles is schematically depicted. Figure 11 Multiple sources for a multi-beam charged particle optical device are schematically depicted; and Figure 12 schematically depicted Figure 11 A plan view of multiple sources is shown.

[0015] The accompanying drawings are illustrative. In the following description of the drawings, the same or similar reference numerals refer to the same or similar parts or entities, and only differences with respect to the various embodiments are described. While the description and drawings relate to electro-optical devices, it should be understood that the embodiments are not intended to limit this disclosure to specific charged particles. Therefore, throughout this document, references to electrons, and items referred to as electrons, can be more generally considered as references to charged particles, and items referred to as charged particles, which are not necessarily electrons. For example, references to electro-optical devices can be more generally considered as references to charged particle optical devices. Detailed Implementation

[0016] There is a trend in the semiconductor industry (often referred to as "Moore's Law") of reducing the physical size of structures representing circuit components on a substrate and / or increasing the packaging density of such structures in order to reduce the physical size of electronic devices and / or enhance their computing power. The physical size of such structures and / or the packaging density of such structures can be reduced by improving lithographic resolution. The manufacturing process of semiconductor IC chips can have hundreds of individual steps. Errors in any step of the manufacturing process can adversely affect the functionality of electronic devices. Improving the overall yield of the manufacturing process is desirable. For example, to achieve a 75% yield for a 50-step manufacturing process (where steps can indicate the number of layers formed on the substrate), each individual step must have a yield greater than 99.4%. If individual steps have a 95% yield, the overall yield of the manufacturing process will be as low as 7 to 8%. Rapid defect identification is desired to maintain high substrate throughput, which is defined as the number of substrates processed per hour.

[0017] Figure 1This is a schematic diagram illustrating an exemplary evaluation apparatus 100, such as a measurement or inspection apparatus. The evaluation apparatus 100 can be configured to scan a sample with a beam of one or more electrons. For example, the sample can be a semiconductor substrate, a substrate made of other materials, or a mask. The electrons interact with the sample and generate interaction products. Interaction products include signal electrons, such as secondary electrons and / or backscattered electrons, and possibly X-ray radiation. The evaluation apparatus 100 can be configured to detect the interaction products from the sample, such that a dataset can be generated, which can be processed into an image or any other data representation of the scanned area of ​​the sample. For clarity, the following description focuses on embodiments where the detected interaction product is signal electrons. The evaluation apparatus 100 can include, for example, a single beam or multiple beams during operation, i.e., multiple beams. Component beams of a multiple beam can be referred to as sub-beams or fine beams. Multiple beams can be used to scan different portions of the sample simultaneously. When the evaluation apparatus 100 uses multiple beams, the evaluation apparatus 100 can evaluate the sample faster than when the evaluation apparatus 100 uses a single beam. For example, using a multi-beam evaluation apparatus can achieve a higher throughput of sample evaluation than a single-beam apparatus.

[0018] Figure 1 The evaluation apparatus 100 includes a vacuum chamber 110, a load-locking chamber 120, an electron optics unit 140, an equipment front-end module (EFEM) 130, and a controller 150. The electron optics unit 140 (also referred to as an electron beam device or electron device) may be located within the vacuum chamber 110. The electron optics unit 140 may include electron optics components (described in more detail below) and an actuable stage. It should be understood that references to the electron optics components of the electron optics unit 140 in the description may be considered as references to the electron optics apparatus itself.

[0019] EFEM 130 includes a first loading port 130a and a second loading port 130b. EFEM 130 may include additional loading ports. The first loading port 130a and the second loading port 130b may, for example, receive a substrate front opening unified cell containing a sample. One or more robotic arms (not shown) in EFEM 130 transfer the sample to a load locking chamber 120.

[0020] Load-lock chamber 120 is used to remove gas surrounding the sample. Load-lock chamber 120 can be connected to a load-lock vacuum pump system (not shown) that removes gas particles from load-lock chamber 120. Operation of the load-lock vacuum pump system causes the load-lock chamber to reach a first pressure below atmospheric pressure. Vacuum chamber 110, which may be the main chamber of evaluation device 100, is connected to a main chamber vacuum pump system (not shown). The main chamber vacuum pump system removes gas molecules from vacuum chamber 110, causing the pressure surrounding the sample to reach a second pressure equal to or below the first pressure. Different sections of electron optics device 140 can have different levels of pressure below atmospheric pressure. After the desired pressure is reached, the sample exits load-lock chamber 120 and is transferred to electron optics device 140 for evaluation. Electron optics device 140 can use a single beam or multiple beams for evaluation. Alternatively, an array of electron optics devices, also known as a multi-tube electron array, can be used, where each electron optics device (or each tube in the multi-tube array) includes, for example, a single beam or multiple beams during operation.

[0021] Controller 150 is electrically connected to electro-optical device 140. Controller 150 may be a processor (such as a computer) configured to control evaluation device 100. Controller 150 may also include processing circuitry configured to perform data, signal, and image processing functions, for example, on a dataset, which may be implemented as a signal, such as a detection signal. Therefore, controller 150 may include processing circuitry configured to perform processing functions on signals, images, and other data generated in evaluation device 100. Although controller 150 is in Figure 1 The controller 150 is shown as being located outside the structure comprising the vacuum chamber 110, the load locking chamber 120, and the EFEM 130, but it should be understood that the controller 150 may be part of the structure. The controller 150 may be located in one of the components of the evaluation device 100, or it may be distributed across at least two of the components.

[0022] Figure 2 This is a schematic diagram illustrating an exemplary electro-optical device 140. The electro-optical device 140 can serve as... Figure 1 A portion of the evaluation apparatus 100 is provided. The electron-optical apparatus 140 includes a source 201 and an electron-optical device 230 (which may also be referred to as an electron-optical lens). The source 201 may include an emitter (not shown) (which may be a cathode) and an extractor and / or an anode (not shown). During operation, the source 201 is configured to emit electrons from the emitter. The electrons may be extracted or accelerated by the extractor and / or the anode to form a source beam 202.

[0023] Electron optics device 230 can be configured to convert source beam 202 into multiple primary beams 211, 212, 213 (which may be referred to as sub-beams or fine beams). Electron optics device 230 can be configured to guide the primary beams 211, 212, 213 along corresponding beam paths toward a sample position targeting sample 208. Although three beams are illustrated, the number of beams can be on the order of hundreds or thousands, for example, no more than 20,000 per electron optics device 140. The multiple beams can be collectively referred to as multiple beams or beam grids. Different beams can be arranged relative to each other in a pattern across the beam grid. The pattern of the beam grid can be referred to as an array. Electron optics device 230 has a field of view that can be defined as a region of the surface of sample 208 in which the primary beams 211, 212, 213 can scan while the aberrations of electron optics device 230 remain within defined values. Alternatively, the field of view can be defined by the maximum scanning range of electron optics device 230. The field of view can be on the order of millimeters, for example, no more than 20 mm at sample 208.

[0024] Electro-optical device 230 includes a plurality of electro-optical elements arranged along a beam path. The electro-optical elements are configured to manipulate the beam. For example, the electro-optical elements may be configured to lens, focus, deflect, or correct the beam. The electro-optical elements may be arranged in a stack of at least one electro-optical element. Such an electro-optical element may be arranged upstream or downstream of the beam current relative to another electro-optical element. The terms "upstream" and "downstream" refer to the direction of the beam from source 201 to sample 208 during use of electro-optical device 230, which may be represented as a direction along one or more beam paths. In embodiments, some of the different electro-optical elements may be in planar form, such as plates 261. An electric field for manipulating the beam may be generated between two plates 261, for example by applying different potentials to adjacent / adjacent plates 261 during use, such as along the beam path. The electric field for manipulating the beam may be generated between the surfaces of plates 261 across the beam path, for example, between adjacent plates 261. One or more beam apertures 266 may be defined in plates 261 for the passage of one or more beams. The beam apertures 266 can be arranged in a pattern, such as a regular grid, like hexagons or squares. Such a pattern of beam apertures 266 can be referred to as an aperture array (i.e., a two-dimensional array on the surface of the plate). The pattern of the beam apertures 266 can correspond to the pattern of the beams within the beam grid. The beam apertures 266 in different plates operating on the same beam are typically aligned.

[0025] Electro-optical elements may include one or more corrector arrays. For example, a corrector array may be integrated into the shape, location, and / or size of the beam aperture 266 of plate 261. The disclosure of such a corrector array as described in WO 2022101072 A1 is incorporated herein by reference. One or more corrector arrays may include multipole deflectors having a specific superposition of potentials applied across individual controllable electrodes. The disclosure of arrays of multipole deflectors in WO2012165955 is incorporated herein by reference.

[0026] One or more electro-optical elements may include apertures for paths of multiple beams. For example, the aperture may be a macroaperture for all of the beams. The disclosures of slit apertures for collimators or correctors including strip electrodes in WO 2021156121 A1 and WO 2021204734 A1 are incorporated herein by reference. One or more electro-optical elements may include one or more plate electrodes whose paths across a beam grid are bent, serving as lens arrays, corrector arrays, and / or collimator arrays, as disclosed in European Patent Application No. 23211553.5, filed November 22, 2023, which is incorporated herein by reference at least with respect to the use and application of bent plate electrodes.

[0027] In the current embodiment, the electron optics device 230 can form three probe points 281, 282, and 283 on the surface of the sample 208. The electron optics device 230 can be configured to deflect primary beams 211, 212, and 213 to scan the probe points 281, 282, and 283 across various scanning regions of the sample 208. In response to the incident primary beams 211, 212, and 213 on the sample 208, signal electrons are generated from the sample 208, which may include secondary electrons and backscattered electrons. Secondary electrons typically have an electron energy of up to 50 eV. Backscattered electrons typically have an electron energy greater than 50 eV and less than the landing energy of the primary beams 211, 212, and 213.

[0028] Electron-optical device 140 includes a sample holder 207 supporting a sample 208. The sample holder 207 supports the sample 208 for evaluation. The sample holder 207 is supported by an actuable stage 209. Electron-optical device 140 also includes a detector array 240. The detector array 240 may be part of the electron-optical device 230. The detector array 240 detects, for example, signal electrons from the sample 208. The detector array 240 generates a detection signal based on the detection of the signal electrons.

[0029] In an embodiment, detector array 240 may define the surface of electro-optical device 140 facing sample 208, such as the bottom surface of electro-optical device 230. More than one detector array may be present at different locations along the path of primary beams 211, 212, 213.

[0030] Detector array 240 may include multiple detector elements, with at least one detector element per beam. Detector elements may be, for example, charge-trapping electrodes, such as metal plates, configured to detect at least some of the signal electrons. Alternatively or additionally, detector elements may include detection diodes configured to detect at least some of the signal electrons. Alternatively or additionally, detector elements may include scintillator materials (such as YAG) configured to convert signal electrons into photons, which can then be detected. Detector elements may be arranged around beam aperture 266 in the bottom surface of electron optics device 230 to allow primary beams 211, 212, 213 to pass toward sample 208. Each detector element may include multiple detection segments, or may constitute a single sensitive surface for each beam. Detection signals generated by the detector elements may be transmitted to a processor for image generation. For example, the detection signals may represent grayscale or intensity values ​​of pixels in an image.

[0031] Detector array 240 can send detection signals, for example as imaging signals or detection signals, to controller 150 or a signal processing system (not shown), which may be part of controller 150. Controller 150 or the signal processing system can be configured to generate an image of the corresponding scanned region of sample 208. Detector array 240 may be at least partially integrated into electro-optical device 230. Alternatively, detector array 240 may be separate from electro-optical device 230. For example, electro-optical device 140 may include secondary electro-optical device configured to direct secondary electrons to detector array 240. In such embodiments, secondary electro-optical device includes a beam splitter (such as a Wien filter, not shown). The beam splitter can separate the path of primary electrons toward sample 208 from the path of signal electrons away from sample 208. Note that such a beam splitter may exist in different embodiments having a detector array within electro-optical device 230 for guiding primary electrons toward the sample and guiding signal particles to detector elements of the detector array.

[0032] Controller 150 (e.g., a control system including a distributed controller) can be connected to Figure 2The various parts (e.g., components) of the electro-optical device 140 include, for example, the source 201, the detector array 240, the electro-optical device 230, and the actuable stage 209. The controller 150 can perform various image processing and signal processing functions. The controller 150 can also generate various control signals to manage the operation of the evaluation device 100.

[0033] Figure 5 An array of electro-optical devices 299 is schematically depicted. In an embodiment, Figure 1 The evaluation apparatus 100 includes an electro-optical device array 299 instead of an electro-optical device 140. Such an electro-optical device array 299 is also referred to as a multi-tube array. Different tubes (or electro-optical devices 230) may include multiple beams, such as a beam grid, in use. In this embodiment, the electro-optical device array 299 includes... Figure 2 Multiple electro-optical devices 230 of the type shown.

[0034] In an embodiment, one or more electro-optical elements may be shared among more than one electro-optical device 230 of the electro-optical device array 299. An electro-optical element may include one or more plates 261, wherein a plurality of beam apertures 266 are defined for corresponding beam paths. In an embodiment, one or more sources 201 may be shared among more than one electro-optical device 230 of the electro-optical device array 299. Sources may be included in a source array having different sources that generate source beams for different corresponding electro-optical devices 230.

[0035] Electro-optical device 230 can simultaneously focus multiple beams onto different regions of the same sample 208. In different embodiments, the electro-optical device 230 of the electro-optical device array 299 can project a single beam onto the sample 208.

[0036] Each electro-optical device 230 of the electro-optical device array 299 can be configured in any of the ways described herein. The disclosure in WO 2022008286 A1 regarding how objectives are incorporated and adapted for multi-device arrangements is incorporated herein by reference. The disclosure in WO 2021165135 A1 regarding multi-beam arrangements including a collimator located at or near the intermediate focal point is incorporated herein by reference.

[0037] In embodiments, any electro-optical element or group of electro-optical elements may be replaceable within the electro-optical device 140 or field-replaceable. Field replaceability means that an electro-optical element or group of electro-optical elements can be replaced without substantially disassembling the electro-optical device 140. In embodiments, the electro-optical device 140 includes at least one module. Each module includes a set of adjacent electro-optical elements. The electro-optical elements of a module may be fixed to each other, for example, as a stack.

[0038] Features in the electron optics plate can be fabricated using techniques from microelectromechanical systems (MEMS), i.e., using MEMS fabrication techniques. MEMS are miniaturized mechanical and electromechanical components fabricated using microfabrication techniques. As an example only, collimator arrays can be formed using MEMS fabrication techniques to achieve spatial compactness. As another example, scan deflector arrays can be formed using MEMS fabrication techniques.

[0039] A power supply can be provided to power the evaluation device 100 and / or the electro-optical device 140. For example, such a power supply can apply a corresponding potential to the electrodes of the lens of the electro-optical device 230.

[0040] In one embodiment, the controller 150 is configured to control the electro-optical device 230. The controller 150 may be configured to control the potential applied to the electrodes of the lens of the electro-optical device 230.

[0041] In an embodiment, controller 150 is configured to control actuable stage 209 to move sample 208 during inspection of sample 208. Controller 150 can cause actuable stage 209 to move sample 208 in one direction, at least during sample inspection, for example continuously, such as at a constant speed, which may be referred to as the type of scan. The speed of actuable stage 209 may be referred to as the rate of movement. Controller 150 can control the movement of actuable stage 209 to vary the speed of movement of sample 208 relative to the beam path according to one or more parameters. Controller 150 can control the deflection of the scan deflector such that the beam path moves relative to actuable stage 209, and thus moves across the surface of sample 208. Controller 150 can vary the beam deflection of the scan deflector according to one or more parameters, and thus vary the scanning of primary beams 211, 212, 213 on sample 208. For example, controller 150 can control the speed of the scan deflector and / or the actuable stage 209 and / or the direction of movement of the actuable stage 209 based on the characteristics of the evaluation process. The disclosure in EP4086933 A1 regarding stepping and scanning strategies for the combination of stage and scan deflector is incorporated herein by reference. The movement rate may include the stepping frequency and / or stage scan rate at different times.

[0042] like Figure 2 As shown, in this embodiment, the electro-optical device 140 includes an electro-optical module 200. The electro-optical module 200 may include a source 201.

[0043] like Figure 3 As shown, in this embodiment, the electro-optical device array 299 includes an electro-optical module 200. The electro-optical module 200 may include a plurality of sources 201. For example, the electro-optical module 200 may include a plurality of sources 201 for respective plurality of electro-optical devices 230.

[0044] Figure 4 An electro-optical module 200 is schematically depicted. The electro-optical module 200 is used in at least one electro-optical device 230. For example... Figure 4 As shown, in this embodiment, the electro-optics module 200 includes one or more sources 201. Sources 201 are described in more detail, for example, with reference to... Figure 7 .

[0045] like Figure 4 As shown, in one embodiment, the electro-optics module 200 includes a vacuum chamber 60. The emitter 21 of each source 201 may be located within the vacuum chamber 60. Components of each source 201 may be located within the vacuum chamber 60. For example, as described in more detail elsewhere, the electro-optics module 200 may include an emitter 21 for each source 201 and a plurality of electro-optical plate elements 24 to 26. In one embodiment, the emitter 21 and the plurality of electro-optical plate elements 24 to 26 are located within the vacuum chamber 60. In another embodiment, one or more sources 201 are located within the vacuum chamber 60.

[0046] In an embodiment, vacuum chamber 60 is configured to maintain a pressurized source within vacuum chamber 60 during use. For example, in an embodiment, electro-optics module 200 includes a pump. The pump is configured to remove gas from vacuum chamber 60. By removing gas from vacuum chamber 60, the pump can be configured to maintain a pressurized source within vacuum chamber 60. The pressurized source can be a threshold pressure or target pressure for the immediate environment of source 201. The pressurized source can be different from the pressurization maintained in other parts of electro-optics device 230.

[0047] Figure 4 The pumping structure for the vacuum chamber 60 is schematically depicted. (For example...) Figure 4 As shown, in this embodiment, a vacuum device 61 is located within a vacuum chamber 60. The vacuum device 61 is provided to maintain a vacuum relative to the emitter 21 of the source 201. In this embodiment, the vacuum device 61 includes a pump.

[0048] like Figure 4As shown, in this embodiment, the vacuum device 61 includes electrodes. For example, the vacuum device 61 may include an anode 71 and at least one cathode 72. Figure 4 Two cathodes 72 are illustrated. An anode 71 may be located between multiple cathodes 72. The anode comprises a conductive material. Cathodes 72 may comprise conductive materials. For example, cathodes 72 may comprise metals, such as titanium. In an embodiment, a power source is configured to maintain a potential difference between the anode 71 and the cathodes 72.

[0049] like Figure 4 As shown, in this embodiment, the vacuum device 61 includes at least one magnetic element 73. For example, Figure 4 The diagram illustrates two magnetic elements 73. An anode 71 can be located between multiple magnetic elements 73. (As shown...) Figure 4 As shown, in an embodiment, one or more of the cathodes 72 may be located between the anode 71 and the magnetic element 73. In an embodiment, the magnetic element 73 is adjacent to the cathode 72. For example, the magnetic element 73 may be in contact with the cathode 72. In an embodiment, the magnetic element 73 includes a magnet, such as a permanent magnet.

[0050] like Figure 4 As shown, in one embodiment, the vacuum device 61 includes a magnetic yoke 74. The magnetic yoke 74 can be configured to guide a magnetic field. The magnetic field can be generated by a magnetic element 73. Figure 4 As shown, in this embodiment, the yoke 74 is adjacent to the magnetic element 73. (As indicated...) Figure 4 As shown, in this embodiment, the yoke 74 extends continuously from one magnetic element 73 to another. Figure 4 As shown, in this embodiment, the magnetic element 73 is located between the cathode 72 and the yoke 74. Figure 4 As shown, in one embodiment, the yoke 74 is located between the anode 71 and the source 201. In another embodiment, the vacuum device 61 is configured to generate a magnetic field, such as a direct current magnetic field.

[0051] like Figure 4 As shown, in this embodiment, the electro-optics module 200 includes at least one blocking element 66. The at least one blocking element 66 is located between the vacuum device 61 and the source 201. Figure 4 As shown, in this embodiment, the electro-optics module 200 includes a plurality of blocking elements. Blocking element 66 may be referred to as a sputtering blocking element. Blocking element 66 is configured to block particles. Figure 4 As shown, a space is provided between the barrier members 66 to allow the passage of gas from the vicinity of source 201. In an embodiment, the barrier member 66 comprises a conductive material. For example, in an embodiment, the barrier member 66 comprises a metal, such as titanium.

[0052] For example, Figure 4As shown, in this embodiment, the vacuum device 61 is located upstream of the emitter 21 relative to each source 201 in the beam direction. The vacuum device 61 can maintain the pressure source without unduly increasing the size of the electro-optics module 200. In this embodiment, the electro-optics module 200 includes a plurality of sources 201. The sources 201 can span the source path (i.e., in... Figure 4 (As shown in the horizontal direction) it extends in an array. The vacuum device 61 can help maintain the pressure source without excessively increasing the size of the electron-optical module 200 in the direction across the source path.

[0053] As described in more detail below (for example, see references) Figures 7 to 9 The electro-optics module 200 may include one or more vents 46. In an embodiment, each vent is configured to provide gas flow to maintain a vacuum within the electro-optics module 200. For example, each vent 46 may be configured such that operation of a vacuum device 61 (e.g., a pump) draws gas through the vent 46.

[0054] Figure 5 A portion of the electro-optical device 140 is schematically depicted. (For example...) Figure 5 As shown, in one embodiment, the emitter 21 and stack 23 of the electron optics module 200 are located within a vacuum chamber 60. In one embodiment, a vacuum device 61 is provided to maintain a vacuum relative to the emitter 21. In one embodiment, the vacuum device 61 includes an ion pump. In one embodiment, the vacuum device includes one or more getters. In one embodiment, the vacuum device 61 is configured to receive gas from a volume containing the emitter 21. The vacuum device 61 may be configured to prevent gas backflow toward the emitter 21. In one embodiment, a magnetic shield 62 is provided between the vacuum device 61 and the emitter 21.

[0055] like Figure 5 As shown, in an embodiment, the electro-optical device 230 may include electro-optical elements downstream of the beam of source 201. For example, in an embodiment, one or more deflector arrays 235 and / or one or more collimator arrays 260 may be provided downstream of the beam of source 201. In an embodiment, the electro-optical elements are provided in a volume different from the volume in which source 201 is located. In an embodiment, the different volumes are maintained at different pressures. In an embodiment, the electro-optical elements define a boundary between two different volumes maintained at different pressures.

[0056] For example, in one embodiment, the source 201, including emitter 21 and stack 23, is located in a volume maintained at a vacuum pressure. In another embodiment, a concentrator array 231 defines a downstream boundary of the beam containing the volume of source 201. In yet another embodiment, the volume immediately downstream of the beam from the concentrator array 231 can be maintained at a different pressure. The concentrator array 231 can define an upstream boundary of the beam from the volume. Figure 5 As shown, in an embodiment, vacuum pump 63 and / or valve (e.g., rotary valve) define the downstream end of the beam volume.

[0057] In one embodiment, valve 64 defines the upstream boundary of the beam containing the volume of deflector array 235. The downstream end of the beam of the volume may be defined by collimator array 260. The volume containing deflector array 235 may be maintained at a different pressure independently of other volumes. In another embodiment, collimator array 260 defines the upstream end of the beam of another volume. The downstream end of the beam of the volume may be defined by objective end array 234 and / or detector 240. The volume may be maintained at a different pressure independently of other volumes.

[0058] Figure 6 The electro-optical device 140 is schematically depicted. (For example...) Figure 6 As shown, in this embodiment, the electro-optical device 140 includes a vacuum chamber 60. (As illustrated...) Figure 6 As shown, in this embodiment, the electro-optics module 200 includes a differential vacuum arrangement. For example, as Figure 6 As shown, in this embodiment, vacuum chamber 60 is included within an outer vacuum chamber 67. In this embodiment, vacuum chamber 60 houses the emitters 21 of a plurality of sources 201. Vacuum chamber 60 may be referred to as an emitter chamber.

[0059] like Figure 6 As shown, in one embodiment, an external vacuum chamber 67 houses the vacuum chamber 60. In another embodiment, the external vacuum chamber 67 also houses at least one electro-optical element. For example, the external vacuum chamber 67 may house an electro-optical device, such as a deflector array.

[0060] In an embodiment, the external vacuum chamber 67 is configured to maintain a pressure higher than that of the pressure source during use. For example, the pressure maintained in the external vacuum chamber 67 may be at least one, optionally at least two, or optionally at least three orders of magnitude higher than that maintained in the vacuum chamber 60.

[0061] In an embodiment, the external vacuum chamber 67 includes at least one vacuum device configured to maintain a vacuum within the external vacuum chamber 67. For example, the external vacuum chamber 67 may be equipped with one or more ion pumps configured to extract gas from the external vacuum chamber 67. For example, the one or more ion pumps may be configured to extract rare gases.

[0062] like Figure 6 As shown, in one embodiment, the electro-optical device 140 includes at least one other chamber in addition to the vacuum chamber 60 and the external vacuum chamber 67. In another embodiment, the electro-optical device 140 includes an intermediate chamber 68 located between the vacuum chamber 60 and the sample 208. In another embodiment, the intermediate chamber 68 houses the detector array 240. In another embodiment, the intermediate chamber 68 houses one or more electro-optical elements, such as an objective lens array.

[0063] like Figure 6 As shown, in one embodiment, the electro-optical device 140 includes a stage chamber 69. The stage chamber 69 houses an actuable stage 209. Figure 6 As shown, in this embodiment, sample 208 is located within stage chamber 69.

[0064] In this embodiment, different chambers are maintained at different pressures. For example, intermediate chamber 68 may be maintained at a pressure higher than vacuum chamber 60, and optionally at a pressure higher than outer vacuum chamber 67. In this embodiment, stage chamber 69 is maintained at a pressure higher than vacuum chamber 60, and optionally at a pressure higher than outer vacuum chamber 67, and optionally at a pressure higher than intermediate chamber 68.

[0065] Figure 7 An electro-optical module 200 according to an embodiment of the present invention is schematically depicted. The electro-optical module 200 may be referred to as a multi-source module. The electro-optical module 200 may include a plurality of emitters 21. Figure 3 As shown, in this embodiment, the electron optics module 200 is used for multiple electron optics devices 230. The electron optics devices 230 can be configured to guide an electron beam along a corresponding beam path toward the sample location where the sample 208 is located.

[0066] like Figure 7 As shown, in this embodiment, the electro-optics module 200 includes a plurality of emitters 21. The emitters 21 can be configured to emit source beams 202 of corresponding electrons. The source beams 202 can be emitted along corresponding source paths. The source path can be the path along which the electrons of the source beam 202 travel. Figure 7Two transmitters 21 of the corresponding source 201 are schematically illustrated. Two transmitters 21 are shown for the purpose of illustrating the features of the electro-optical module 200. The electro-optical module 200 may include at least three, optionally at least five, optionally at least ten, optionally at least twenty, optionally at least fifty, optionally at least one hundred, optionally at least two hundred, optionally at least five hundred, and optionally at least one thousand transmitters 21 of the corresponding source 201.

[0067] In an embodiment, each source 201 is configured to generate a source beam 202 for a corresponding electro-optical device 230. Each electro-optical device 230 may include one or more electro-optical elements downstream of the beam of source 201. In an embodiment, source 201 includes a Schottky source. Additionally or alternatively, source 201 may include a cold field emitter.

[0068] like Figure 7 As shown, in this embodiment, the electro-optics module 200 includes a plurality of electro-optical plate elements 24 to 26. The electro-optical plate elements 24 to 26 are configured to operate on the source beam. For example, the electro-optical plate elements 24 to 26 may help define one or more electromagnetic fields that influence the electrons of the source beam.

[0069] like Figure 7 As shown, in this embodiment, a plurality of beam apertures 266 are defined in the electron optical plate elements 24 to 26. The beam apertures 266 are configured for the passage of the source beam. Figure 7 As shown, in this embodiment, the beam aperture 266 is aligned relative to the transmitter 21.

[0070] like Figure 7 As shown, in one embodiment, source 201 includes a corresponding emitter 21. In another embodiment, the electron optics element includes an extractor device 25. The extractor device 25 is configured to operate on the source beam. In one embodiment, during operation, emitter 21 is configured to emit electrons. Electrons can be extracted or accelerated by the extractor device 25 to form source beam 202.

[0071] like Figure 7 As shown, in this embodiment, at least one of the electron optical plate elements 24 to 26 is shared by a plurality of transmitters 21. Figure 7 As shown, in this embodiment, at least two pairs of the electron optical plate elements 24 to 26 are shared among a plurality of transmitters 21. At least one pair of the electron optical plate elements 24 to 26 is shared among all the transmitters 21 of the electron optical module 200. Alternatively, at least one subset of the electron optical plate elements 24 to 26 is shared among the transmitters 21 of the electron optical module 200.

[0072] like Figure 7As shown, in this embodiment, electron optical plate elements 24 to 26 extend across the source path of the source beam. Electron optical plate elements 24 to 26 may extend between adjacent emitters 21. Figure 7 As shown, in an embodiment, the electro-optical plate elements 24 to 26 may extend substantially perpendicular to the source path of the source beam emitted by the transmitter 21.

[0073] like Figure 7 As shown, in this embodiment, the electron optical plate elements 24 to 26 are substantially planar. The electron optical plate elements 24 to 26 may include a main plane. An electromagnetic field can be established between the opposing surfaces. The electromagnetic field can affect the electrons of the source beam emitted by the transmitter 21.

[0074] Electro-optical elements 24 to 26 do not have to be completely planar. For example, one or more of electron-optical elements 24 to 26 can be curved, such as bowl-shaped. Such a bowl-shaped electron-optical element has a plate-like shape.

[0075] In an embodiment, the extractor device 25 is configured to operate on the source beam individually. The extractor device 25 can help define one or more electromagnetic fields that influence electrons in the source beam. The extractor device 25 can be configured such that at least one electromagnetic field in the electromagnetic field can be different for source beams from different emitters 21. For example, the extractor device 25 can be arranged such that the amplitude and / or shape of the electromagnetic field can be different for different source beams.

[0076] Embodiments of the present invention are expected to facilitate easier alignment of emitter and extractor electrodes of multiple sources 201. Embodiments of the present invention are expected to reduce the time required to align the emitter and extractor electrodes of sources 201. For example, emitter 21 can be aligned relative to extractor device 25 during assembly of electro-optics module 200. Sources 201 can then be integrated into electro-optics device array 299, for example, as... Figure 3 As shown. By aligning the emitter 21 relative to the extractor device 25 during the assembly of the electro-optics module 200, it may not be necessary to align the emitter relative to the extractor electrode after the source 201 has been integrated into the electro-optics device array 299.

[0077] Embodiments of the present invention are expected to improve the accuracy of controlling the beam current of a source beam generated by multiple sources 201. By operating the source beams individually with the extractor device 25, the beam current of the source beams can be controlled individually. For example, it may be possible to provide multiple sources 201 that have more consistent beam currents relative to each other.

[0078] Figure 8 schematically depicted Figure 7 A plan view of the stack 23 of the electron optical plate elements 24 to 26 shown. Figure 9 A side view of the stack 23 of electron optical plate elements 24 to 26 is schematically depicted. Figure 9 The side view shown is along Figure 8 The cross-sectional view shown is captured by the dotted line.

[0079] like Figures 7 to 9 As shown, in this embodiment, the electro-optics module 200 includes a plurality of spacers 33, 36. The spacers 33, 36 are configured to space the plurality of electro-optics plate elements 24 to 26 apart from each other.

[0080] For example, in one embodiment, the electron optics plate element includes a suppressor 24. The suppressor 24 may be shared by multiple emitters 21. The suppressor 24 may be configured to suppress any unwanted electron current. Figure 7 As shown, in this embodiment, the electron optics plate element includes an anode 26. For example, an emitter 21 may form a corresponding cathode. During operation, the emitter 21 can be configured to emit electrons. The electrons can be accelerated by the anode 26 to form a source beam. Figure 7 As shown, in this embodiment, the anode 26 is shared by multiple emitters 21. For example, Figure 7 The anode 26 shown is shared by the two sources 201 shown.

[0081] For example, Figure 7 A plurality of spacers 33 are schematically depicted, configured to space the suppressor 24 from the extractor device 25. As another example, Figure 8 and Figure 9 A plurality of spacers 36 are schematically depicted, configured to space the suppressor 24 from the anode 26. In embodiments, other pairs of electro-optical plate elements are spaced apart from each other by one or more spacers. For example, in an embodiment, the electro-optical module 200 includes one or more spacers configured to space the extractor device 25 from the anode 26.

[0082] In an embodiment, the electro-optical plate elements include one or more electro-optical plate elements other than the suppressor 24, the extractor device 25, and the anode 26. In an embodiment, the suppressor 24 may be omitted. In an embodiment, the anode 26 may be omitted. In an embodiment, the electro-optical module 200 includes one or more spacers configured to space such other electro-optical plate elements apart from each other and / or from one or more of the suppressor 24, the extractor device 25, and the anode 26.

[0083] like Figure 7 As shown, in an embodiment, each emitter 21 includes a tip 22. The emitter 21 is configured to emit electrons from the tip 22. Figure 7As shown, in this embodiment, the tip 22 is located upstream of the beam of the extractor device 25. As... Figure 7 As shown, in one embodiment, the tip 22 of the transmitter 21 extends through a beam aperture 266 defined in at least one electro-optical plate element (e.g., a suppressor 24). Figure 7 As shown, in an embodiment, the distance between the tip 22 of the transmitter 21 and the extractor device 25 is less than the distance between the extractor device 25 and the electron optical plate element upstream of the beam of the extractor device 25 (e.g., the suppressor 24).

[0084] In embodiments, spacers 33, 36 are configured to mechanically support electron optical plate elements relative to each other. For example, spacers 33, 36 may be fixed to electron optical plate elements 24 to 26. Electron optical plate elements 24 to 26 may be fixed relative to each other via spacers 33, 36. Embodiments of the invention are expected to improve the mechanical stability of multiple sources 201, such as the stacking of electrodes included in multiple sources. Additionally or alternatively, the electron optical module 200 may include one or more frames configured to mechanically support electron optical plate elements relative to each other. Such frames are optional. Spacers 33, 36 may provide sufficient mechanical support for electron optical plate elements 24 to 26.

[0085] In this embodiment, spacers 33 and 36 are configured to electrically isolate the electro-optical plate elements 24 to 26 from each other. For example, spacers 33 and 36 may be arranged such that a gap is provided between adjacent electro-optical plate elements 24 to 26. Spacers 33 and 36 may comprise an electrically insulating material, such as quartz. Spacers 33 and 36 may be configured to reduce the likelihood of undesirable electrical breakdown between the electro-optical plate elements 24 to 26.

[0086] During operation of the electro-optics module 200, electro-optical plate elements 24 to 26 can be maintained at different potentials. For example, one or more power sources can be electrically connected to the electro-optical plate elements 24 to 26. The one or more power sources can be configured to apply a potential to each charged particle optical plate element in the electro-optical plate elements 24 to 26. For example, the controller 150 of the electro-optical device 140 can be configured to control one or more power sources to control the potential of the electro-optical plate elements 24 to 26. Embodiments of the present invention are expected to reduce the possibility of undesirable electrical breakdown.

[0087] In embodiments, spacers 33 and 36 are configured to mechanically support the extractor device 25 relative to the beam path of the source beam. For example, spacer 33 may be configured to mechanically support the extractor device 25 at a predetermined distance from the suppressor 24 for a given source beam emitted from a given transmitter 21. In embodiments, spacers 33 and 36 are configured to mechanically support the extractor device 25 individually relative to the beam path of the source beam, such that the extractor device 25 is configured to operate on the source beam individually. By controlling the position of the extractor device 25 relative to the beam path of the source beam, the extractor device can influence the source beam differently for different source beams. Embodiments of the present invention are expected to improve the accuracy of controlling the current beam of a given source beam.

[0088] In an embodiment, spacer 33 is configured to shape extractor device 25 under thermal load during operation. During use of the electro-optics module 200, thermal loads may exist on one or more components of the electro-optics module 200. For example, electrons emitted by emitter 21 may heat the components to which they are incident. Emitter 21 can be heated to increase beam current. Heat can be radiated from emitter 21 to other components of the electro-optics module 200. The power supplied to components such as electro-optics plate elements 24 to 26 may cause these components to heat. Such thermal loads may cause components to change shape. For example, components subjected to thermal loads may expand. Expansion can be predictable.

[0089] Thermal loads can cause deformation. For example, thermal loads can cause deformation of one or more extractor electrodes 27 of the extractor device 25. For example, spacers may be thermally shaped during operation. As the spacers expand, the extractor electrodes 27 may be deformed.

[0090] In an embodiment, the electro-optical module 200 is calibrated such that anticipated thermal expansion is intentionally used to shape the extractor device 25. For example, in an embodiment, spacers 33 are positioned relative to at least some of the extractor electrodes 27 in the extractor device 25 such that, under thermal loads applied during operation, the extractor electrodes 27 included in the extractor device 25 individually operate the source beam. In an embodiment, the size of the spacers 33 is selected to control the position of the extractor device 25 (e.g., the extractor electrodes 27 of the extractor device 25) relative to the emitter 21.

[0091] In an embodiment, the extractor device 25 includes a plurality of extractor electrodes 27, such as... Figure 7 As shown. In Figure 7 In the arrangement shown, the extractor device 25 includes an extractor electrode 27 for each emitter 21. The extractor electrodes 27 may be arranged in a common plane. The extractor device 25 may be formed into a layer including a plurality of extractor electrodes 27.

[0092] In one embodiment, the extractor electrode 27 included in the extractor device 25 operates individually on the source beam such that thermal expansion of the extractor electrode 27 in the extractor device 25 causes a corresponding movement of the corresponding position of the extractor electrode 27 relative to the source path of the source beam. In another embodiment, the extractor electrode 27 included in the extractor device 25 operates individually on the source beam such that thermal expansion of the spacer 33 causes a corresponding movement of the corresponding position of the extractor electrode 27 relative to the source path of the source beam. Thermal expansion caused by thermal load during operation of the electro-optics module 200 can be taken into account. Thermal expansion can be used to control the beam current generated by the emitter 21 of the source 201 of the electro-optics module 200. Embodiments of the invention are expected to more accurately control different emitters 21 differently.

[0093] like Figure 7 As shown, in this embodiment, the spacer 33 is configured to mechanically support the extractor device 25. For example, as Figure 7 As shown, in one embodiment, the spacer 33 is configured to mechanically support the extractor device 25 relative to the suppressor 24. The extractor device 25 can be fixed to the downstream end of the spacer 33. The upstream end of the spacer 33 can be fixed to the suppressor 24. In an alternative embodiment, the upstream end of the spacer is fixed to the extractor device 25, and the downstream end of the spacer is fixed to the anode 26. The position of the extractor device 25 relative to the emitter 21 can be controlled by controlling the dimensions of the spacer 33.

[0094] like Figure 8 As shown, in this embodiment, for each source beam, a plurality of spacers 33 are configured to mechanically support the extractor device 25. By providing a plurality of spacers 33 to mechanically support the extractor device 25, the orientation of the extractor device 25 relative to the transmitter 21 can be controlled more precisely. For example, undesirable tilting of the extractor device 25 relative to the transmitter 21 can be reduced.

[0095] like Figure 8 As shown, in this embodiment, for each source beam, at least three spacers 33 are configured to mechanically support the extractor device 25. By providing at least three spacers 33, the orientation of the plate-like shape of the extractor device 25 relative to the emitter 21 can be controlled. By providing three spacers 33, the planarity of the extractor device 25 can be controlled for each source beam. Figure 8 As shown, in this embodiment, only three spacers 33 are configured to mechanically support the extractor device 25 for each source beam. In an alternative embodiment, more than three spacers 33 are provided to mechanically support the extractor device 25 for each source beam.

[0096] like Figure 8 As shown, in this embodiment, the spacers 33 are uniformly distributed in a circumferential direction around the source path of each source beam. In the case where more than three spacers 33 are provided for each source beam, in this embodiment, the spacers 33 are arranged to be uniformly distributed in a circumferential direction around the source path.

[0097] For example, Figure 7 and Figure 8 As shown, in this embodiment, the extractor device 25 includes a plurality of extractor electrodes 27. (As illustrated...) Figure 8 As shown, the extractor electrodes 27 are separated from each other. The extractor electrodes 27 can be arranged such that there is a gap between adjacent extractor electrodes 27. Figure 8 In the arrangement shown, there are three extractor electrodes 27. In alternative embodiments, the number of extractor electrodes 27 is at least five, optionally at least ten, optionally at least twenty, optionally at least fifty, optionally at least one hundred, optionally at least two hundred, optionally at least five hundred, and optionally at least one thousand.

[0098] like Figure 8 As shown, in this embodiment, each extractor electrode 27 is configured to operate on a different source beam. For example, each extractor electrode 27 can be configured to operate on a different source beam separately. By providing different extractor electrodes 27, the extractor electrodes can be individually controllable. For example, one or more power sources can be configured to apply different potentials to different extractor electrodes 27. By applying different potentials to different extractor electrodes 27, the source beams can be controlled individually. For example, the beam currents of different source beams output by different transmitters 21 can be controlled individually.

[0099] like Figure 8 As shown, in this embodiment, each extractor electrode 27 has a plurality of spacers 33. For example, as Figure 8 As shown, each extractor electrode 27 can have three spacers 33. By providing three spacers 33 for each extractor electrode 27, the plane of the extractor electrode 27 can be defined by the spacers 33. By providing three spacers 33 for each extractor electrode 27, the influence of the extractor electrode 27 on the source beam can be controlled more accurately and reliably.

[0100] For example, Figure 7 or Figure 9 As shown, in this embodiment, spacer 33 is substantially planar. For example, spacer 33 may be disc-shaped. However, spacer 33 does not necessarily have to be substantially planar. For example, spacer 33 may have a dimension along the source path that is larger than the dimension of its cross-beam path. Figure 9 In this orientation, the spacer 33 may have a height that is at least as large as its width, or greater than its width.

[0101] like Figure 9 As shown, in this embodiment, the spacer 33 is substantially parallel to one or more of the electron optical plate elements 24 to 26. For example, as Figure 9 As shown, spacer 33 may be substantially parallel to suppressor 24. In an embodiment, spacer 33 is substantially parallel to extractor device 25 (e.g., parallel to extractor electrode 27 of extractor device 25). In an embodiment, spacer 33 is substantially parallel to anode 26.

[0102] like Figure 8 As shown, in this embodiment, the spacer 33 has a substantially similar shape in at least two dimensions. For example, in a plan view, the spacer 33 may be circular. Alternatively, the spacer 33 may be, for example, square or hexagonal in a plan view. A plan view refers to a view along the source path of the source bundle. In this embodiment, the spacer 33 has a substantially similar shape in cross-section. In this embodiment, the spacer 33 is substantially sized the same in the direction across the source path.

[0103] For example, Figure 7 or Figure 9 As shown, in this embodiment, spacers 33 and 35 have a rim profile. For example, spacers 33 and 36 may include a radially inner portion 34 and a radially outer portion 35. The radially outer portion 35 is located radially outside the radially inner portion 34. The radially inner portion 34 and the radially outer portion 35 may be integrally formed with each other.

[0104] like Figure 7 and Figure 9 As shown, in this embodiment, the radially inner portion 34 and the radially outer portion 35 may have different dimensions. For example, the radially inner portion 34 may have a larger dimension than the radially outer portion 35 in the direction along the source path of the source bundle. The radially inner portion 34 and the radially outer portion 35 may be arranged such that the spacers 33, 36 have a rim profile.

[0105] For example, Figure 9 As shown, in this embodiment, the radially inner portion 34 is fixed to the surfaces of two adjacent electro-optical plate elements 24 to 26 spaced apart by spacers 33 and 36. The radially outer portion 35 can be fixed to the surface of only one of the two electro-optical plate elements 24 to 26, with spacers 33 and 36 configured to space the two electro-optical plate elements 24 to 26. Figure 9As shown, in this embodiment, the radially outer portion 35 is fixed to the upstream electron optical plate element of the two electron optical plate elements, and spacers 33 and 36 are configured to space the two electron optical plate elements apart. For example, spacer 33 may fix its radially outer portion 35 to the suppressor 24 only. The radially outer portion 35 of spacer 33 may be kept at a distance from the extractor electrode 27 of the extractor device 25. Spacer 36 may have a radially outer portion 35 fixed to the suppressor 24 only. The radially outer portion 35 of spacer 36 may be kept at a distance from the anode 26.

[0106] For example, Figure 9 As shown, in this embodiment, the rim profile has a path length on the surface of the rim that is greater than the thickness of the spacers 33 and 36. By providing the rim profile, the possibility of undesirable electrical breakdown between the spaced-out electro-optical plate elements can be reduced.

[0107] like Figure 9 As shown, in one embodiment, the rim profile includes a step. The step provides an abrupt change in the dimensions of the spacers 33, 36 in the cross-source path direction. However, the rim profile does not necessarily have to have a step. In an alternative embodiment, the rim profile may include gradually changing dimensions of the spacers 33, 36 in the cross-source path direction. By making the rim profile include a step, the spacers 33, 36 can have a stepped rim.

[0108] In one embodiment, the extractor device 25 includes an extractor electrode 27 shared by multiple source beams. For example, Figure 7 or Figure 8 The extractor electrodes 27 shown can, for example, be connected together to form a single integral plate. The resulting extractor electrodes can be shared for multiple source beams. By providing extractor electrodes 27 shared for multiple source beams to the extractor device 25, the total number of components in the electro-optics module 200 can be reduced. The construction of the electro-optics module 27 can be simplified.

[0109] In an embodiment, the extractor device 25 includes a plurality of extractor electrodes 27, each extractor electrode 27 being configured to operate on a selected portion of a plurality of source beams. For example, each extractor electrode may be configured to operate on a plurality of different source beams. In an embodiment, the extractor electrodes 27 are configured to operate on a corresponding source beam. For example, the extractor electrodes may be configured to operate on different individual source beams. The extractor electrodes 27 may be individually controllable. For example, the controller 150 may be configured to control one or more power supplies to individually control the potential applied to each extractor electrode 27. The potentials supplied to the different extractor electrodes 27 may be controlled independently of each other.

[0110] like Figure 4 ,6 As shown in Figure 7, in an embodiment, vents 46 are defined in one or more of the electron optical plate elements 24 to 26. The vents 46 are separate from the beam aperture 266 defined in the electron optical plate elements 24 to 26. In an embodiment, a plurality of vents 46 are defined in one or more of the electron optical plate elements 24 to 26.

[0111] like Figure 8 As shown, in this embodiment, the vents 46 defined in the different electro-optical plate elements 24 to 26 can be aligned with each other, for example, in the direction along the source path. For example, Figure 8 The three vents 46 shown, positioned closest to the center of stack 23, are aligned in the direction along the source path within the suppressor 24 and anode 26. In an embodiment, one or more vents 46 are provided that extend only partially through stack 23. For example, as... Figure 9 As shown, the vent 46 provided to the right side of the figure is defined in the suppressor 24 but is not aligned with the corresponding vent in the anode 26. This vent may be referred to as a vent hole.

[0112] In this embodiment, the vent 46 is configured to provide a flow of gas through the electro-optical plate elements 24 to 26. Each electro-optical plate element does not necessarily have at least one vent 46 defined therein. For example, as... Figure 9 As shown, in this embodiment, the extractor device 25 does not have a vent defined therein. The extractor device 25 may have a beam aperture 266 defined therein. In this embodiment, the beam aperture 266 is the only aperture or hole defined in the extractor electrode 27 of the extractor device 25. By providing a vent, the gas flow through the stack 23 can be increased. The beam aperture 266 can provide some gas flow through the stack 23 by providing a vent 46, which can increase the gas flow compared to providing only the beam aperture 266 for gas flow.

[0113] For example, Figure 9 As shown, in one embodiment, the vents 46 defined in different electro-optical elements are aligned with each other. In another embodiment, the vents 46 defined in different electro-optical elements are aligned with the transmitter.

[0114] like Figure 8 As shown, in one embodiment, at least one vent 46 is located equidistant from at least two other vents 46. In another embodiment, at least one vent 46 is located substantially equidistant between adjacent bundle paths.

[0115] In one embodiment, gas flow is used to maintain a vacuum within the electro-optics module 200. For example, in one embodiment, the pressure within the electro-optics module 200 is maintained at a lower level compared to the pressure in one or more volumes outside the electro-optics device 140. It may be desirable to increase the gas flow through the stack 23 so that the low pressure is maintained.

[0116] Figure 10 An electro-optical module according to an alternative embodiment is schematically depicted. (As shown) Figure 10 As shown, in this embodiment, the electro-optics module includes a single source 201. The electro-optics module does not necessarily include multiple sources 201.

[0117] like Figure 10 As shown, in this embodiment, the electro-optical module includes a single emitter 21. Emitter 21 is configured to emit a source beam of electrons. Figure 10 As shown, in an embodiment, the electro-optical module includes a plurality of electro-optical plate elements 24 to 26.

[0118] Figure 10 Some of the features shown are described elsewhere with reference to other accompanying drawings. These features may be as described elsewhere. For example, emitter 21, suppressor 24, extractor electrode 27, anode 26, and spacers 33, 36 may be as described elsewhere. Figures 7 to 9 As described.

[0119] In an embodiment, source 201 includes an avalanche diode structure. The avalanche diode structure includes a stack of doped semiconductor junctions and is biased from two connections. For example, the avalanche diode structure may include a PN junction or a PIN junction. The avalanche diode structure may include a homojunction or a heterojunction of stacked semiconductors with different band gaps. In an embodiment, the avalanche diode structure includes a heterojunction of a silicon carbide P-type substrate with a gallium nitride N++ layer on top of it. Gallium nitride has a lower work function (approximately 1 eV lower), and therefore more electrons can escape from it. Meanwhile, silicon carbide has high thermal conductivity and the ability to be P-type. The band gap structure affects the electron energy distribution in the avalanche region of the avalanche diode structure. Source 201 may be based on an avalanche electron emission diode (AEED) as the emitter technology. AEED emitters are semiconductor-based emitters. AEEDs may alternatively be referred to as avalanche cold cathodes or semiconductor junction cold cathodes. In an embodiment, source 201 is junction-based. For example, emitter 21 may include a diode junction, such as a PN junction. In an embodiment, source 201 includes multiple junctions. Each junction can be an interface between two layers or two regions of similar or dissimilar semiconductors. In an embodiment, the junction is an interface between doped materials. A junction can be a junction between two or more materials. Such a junction can be a diode. In an embodiment, source 201 is configured such that an avalanche current is generated inside the diode of emitter 201, which is perpendicular to the surface facing sample 208. Some electrons are sufficiently excited in the avalanche region to overcome the work function of the surface and are emitted into the vacuum.

[0120] Figure 11 Multiple sources 201 for the multi-beam electro-optical device 230 are schematically depicted. Figure 11 The vacuum chamber 60 of the electron optics module is schematically depicted. Figure 11 In the arrangement shown, source 201 may include an avalanche diode structure, such as as described above. The vacuum chamber may be located within an external vacuum chamber 67, such as as shown in reference... Figure 6 As described.

[0121] like Figure 11 As shown, in this embodiment, a vacuum device 61 is provided for the vacuum chamber 60. The vacuum device 61 is configured to maintain a pressurized source within the vacuum chamber 60 during use. For example, the vacuum device 61 may include one or more pumps. In this embodiment, the vacuum device 61 includes one or more getters.

[0122] like Figure 11 As shown, in this embodiment, source 201 is located between vacuum device 61 and beam path. Vacuum device 61 is in the upstream direction of the beam relative to source 201.

[0123] like Figure 11As shown, in this embodiment, the electro-optical module includes a plurality of sources 201. Each source 201 may include a corresponding emitter 21. The emitters 21 may be arranged in an array.

[0124] Figure 12 schematically depicted Figure 11 The diagram shows a plan view of the source 201 arranged above sample 208. Figure 12 As shown, in one embodiment, the electron optics module 200 includes at least one substrate element 80. In another embodiment, a plurality of substrate elements 80 are provided. Each substrate element 80 may include a plurality of emitters 21 configured to emit a source beam of corresponding electrons along a corresponding source path. In another embodiment, the substrate element 80 is substantially planar. In another embodiment, each substrate element 80 may be a plate. In another embodiment, each substrate element 80 extends along a plane of the beam-crossing path.

[0125] like Figure 12 As shown, in this embodiment, one or more vents 46 are defined in at least one substrate element 80. For example, the vents 46 may be formed as gaps between adjacent substrate elements 80. The vents 46 may be configured for gas conduction. The vents 46 may help maintain a pressurized source within the vacuum chamber 60.

[0126] like Figure 11 As shown, in one embodiment, the electro-optics module includes an anode element 81, which may be referred to as an anode array. The anode element 81 may be configured to serve as an anode for the source 201. In one embodiment, the anode element 81 also includes a separate beam corrector for correcting individual source beams emitted by the emitter 21 of the source 201. In one embodiment, the anode element 81 is a planar element, such as a plate.

[0127] like Figure 11 As shown, in one embodiment, the electro-optics module includes a beam-limiting aperture array 82. The beam-limiting aperture array 82 may have a plurality of beam-limiting apertures defined therein. The beam-limiting apertures may be configured to limit the source beam emitted by source 201. The beam-limiting aperture array 82 may be configured to block one portion of the electron current and transmit another portion of the electron current. In one embodiment, the beam-limiting aperture array 82 is substantially planar, such as a plate.

[0128] In an embodiment, the anode element 81 is configured to guide the source beam through the beam-limiting aperture of the beam-limiting aperture array 82.

[0129] like Figure 7As shown, in one embodiment, the electro-optics module 200 includes a condenser array 231. In this embodiment, a condenser array 231 is provided for each emitter 21. The condenser array 231 can be considered part of the electro-optics module 200. For example, the condenser array 231 can be fixed to the stack 23 of the electro-optics modules 200 during assembly. The condenser array 231 can be fixed relative to the emitter 21 before the electro-optics module 200 is incorporated into the electro-optics device 230 or the electro-optics apparatus 140. Alternatively, the condenser array 231 can be omitted from the electro-optics module 200. The condenser array 231 of the electro-optics device 230 can be fixed relative to the emitter 21 after the electro-optics module 200 has been incorporated into the electro-optics device 230 or the electro-optics apparatus 140.

[0130] like Figure 7 As shown, in one embodiment, the electro-optics module 200 includes a concentrator frame 32. The concentrator frame 32 is configured to secure a concentrator array 231 to a stack 23. In another embodiment, multiple concentrator frames 32 are provided to secure respective concentrator arrays 231 to respective emitters 21.

[0131] like Figure 7 As shown, in this embodiment, the concentrator array 231 is fixed to the downstream element of the stack 23. For example, as Figure 7 As shown, in this embodiment, the downstream element of the stack 23 is the anode 26. In this embodiment, the concentrator frame 32 is configured to secure the anode 26 to the concentrator array 231. For example, the concentrator frame 32 may be directly secured to both the anode 26 and the concentrator array 231. The concentrator frame 32 is configured to fix the position of the concentrator array 231 relative to the stack 23.

[0132] like Figure 7 As shown, in an embodiment, the electron optics module 200 includes one or more electron absorbers 41, 42. For example, an electron absorber 41 may be provided on the surface of the anode 26. For example, the electron absorber 41 may be provided on the upstream surface of the anode 26. In an embodiment, the electron absorber 42 is provided on the surface of the extractor device 25. For example, the electron absorber 42 may be located on the downstream surface of the extractor device 25.

[0133] like Figure 7As shown, in this embodiment, an electron absorber 41 is provided at the anode 26 corresponding to each emitter 21. An electron absorber 42 may be provided at the extractor device 25 for each emitter 21. In this embodiment, the electron absorbers 41, 42 are formed to substantially surround the source path when viewed in a plan view (i.e., when viewed along the source path). For example, the electron absorbers 41, 42 may be formed into a ring.

[0134] In one embodiment, one or more electron absorbers are provided on the upstream surface of the extractor device. In another embodiment, one or more electron absorbers are located on the downstream surface of the suppressor 24.

[0135] In this embodiment, electron absorbers 41 and 42 are configured to reduce the current of electrons in the radially outward direction relative to the source path. Electron absorbers 41 and 42 do not necessarily need to be formed as rings. In alternative arrangements, electron absorbers 41 and 42 may comprise multiple arc segments or multiple elongated segments when viewed in a plan view (i.e., when observed along the beam path).

[0136] like Figure 7 As shown, in this embodiment, a recess 49 may be provided on the surface facing (or opposite) the electron absorbers 41, 42. For example, a recess 49 is provided in the downstream surface of the extractor device 25 opposite to the electron absorber 41. Similarly, a recess 49 is provided on the upstream surface of the anode 26 opposite to the electron absorber 42 provided on the downstream surface of the extractor device 25. By providing the recess, the size of the gap between adjacent electron optical plate elements can become more uniform in the direction of the cross-beam path. By making the gap size more uniform, the amplitude of the electric field can be more uniform. Undesirable peaks in the amplitude of the electromagnetic field can be reduced. By avoiding high peaks in the amplitude of the electromagnetic field, the possibility of undesirable electrical breakdown can be reduced.

[0137] By reducing the current of electrons radially outward from the source path, the likelihood of parts of the source module 200 becoming undesirably charged can be reduced. For example, the likelihood of spacers 33 and 36 becoming undesirably charged can be reduced. By reducing the charge on components having spacers 33 and 36, the likelihood of undesirable electrical breakdown can be reduced.

[0138] For example, Figure 7 As shown, in this embodiment, the elements of the electro-optical module 200 are aligned. For example, the elements of the electro-optical module 200 may be aligned prior to assembly. Alignment may be performed before the electro-optical module 200 is incorporated as part of the electro-optical device 140 or the electro-optical apparatus 230. Additional alignment may be performed to align the electro-optical module 200 with respect to other electro-optical elements of the electro-optical device 230 or the electro-optical device 140.

[0139] In an embodiment, each electro-optical device 230 includes an electro-optical element downstream of the beam of the electro-optical module 230. The electro-optical elements of the electro-optical device 230 can be configured to operate on the source beam. The electro-optical elements can be configured to operate on a primary beam derived from the source beam generated by the electro-optical module 200.

[0140] In one embodiment, the electro-optical elements of the electro-optical device 230 are configured to operate on a corresponding source beam or a primary beam derived from a corresponding source beam. Alternatively, the electro-optical elements may be configured to operate on multiple source beams or multiple primary beams derived from multiple source beams. There may be a source 201 for each electro-optical device 230. Alternatively, there may be multiple sources 201 for each electro-optical device 230. Alternatively, the primary beams for multiple electro-optical devices 230 may be derived from the source beam of a single source 201. The source 201 may be included in the same electro-optical module 200.

[0141] In an embodiment, the evaluation apparatus 100 includes an electro-optical device 140. The electro-optical device 140 may include a plurality of electro-optical devices 230. Each electro-optical device 230 may include at least one detector 240. When the sample is supported in the sample position, the detector 240 may be configured to detect signal particles from the sample 208. In an embodiment, at least one detector 240 includes one or more of electro-optical plate elements. The detector interacts with electrons, thus it can be considered an electro-optical element.

[0142] Further embodiments of the invention are given in the following numbered clauses: 1. A charged particle optical module for a charged particle optical device configured to guide a beam of charged particles toward a sample location along a beam path, the charged particle optical module comprising: The transmitter is configured to emit a beam of charged particles along the source path; A plurality of charged particle optical plate elements are configured to operate on the source beam, wherein each charged particle optical plate element is defined as follows: A beam aperture, configured for the passage of the source beam; and A vent is configured to provide gas flow through the charged particle optical plate elements in order to maintain a vacuum within the charged particle optical module; and A vacuum chamber, in which the emitter and the plurality of charged particle optical plate elements are located, the vacuum chamber being configured to maintain a pressurized source during use. 2. A charged particle optical module for use with a plurality of charged particle optical devices configured to guide a charged particle beam toward a sample location along a beam path, the charged particle optical module comprising: A substrate element, comprising a plurality of emitters configured to emit source beams of corresponding charged particles along respective source paths; and At least one charged particle optical plate element is configured to operate on the source beam, and a plurality of beam apertures are defined, the beam apertures being configured to allow the source beam to pass through. A vent is defined in the substrate element and / or the at least one charged particle optical plate element, the vent being configured to provide gas flow through the element to maintain a vacuum within the charged particle optical module; and A vacuum chamber, in which the emitter and the at least one charged particle optical plate element are located, the vacuum chamber being configured to maintain a pressurized source during use. 3. The charged particle optical module according to clause 1 or 2, comprising: A pump is configured to remove gas from the vacuum chamber to maintain the pressurized source within the vacuum chamber. 4. The charged particle optical module according to Clause 3, wherein the pump is located upstream of the beam relative to the emitter. 5. A charged particle optical module for a charged particle optical device configured to guide a beam of charged particles toward a sample location along a beam path, the charged particle optical module comprising: The transmitter is configured to emit a beam of charged particles along the source path; Multiple charged particle optical plate elements are configured to operate on the source beam, wherein a beam aperture is defined in each charged particle optical plate element and the beam aperture is configured for the passage of the source beam; A vacuum chamber, in which the emitter and the plurality of charged particle optical plate elements are located, the vacuum chamber being configured to maintain a pressurized source during use; and A pump is configured to remove gas from the vacuum chamber in order to maintain the pressurized source within the vacuum chamber during use, wherein the pump is located upstream of the beam relative to the emitter. 6. A charged particle optical module for use with a plurality of charged particle optical devices configured to guide a charged particle beam toward a sample location along a beam path, the charged particle optical module comprising: A substrate element, comprising a plurality of emitters configured to emit source beams of corresponding charged particles along respective source paths; and At least one charged particle optical plate element is configured to operate on the source beam, and a plurality of beam apertures are defined in the at least one charged particle optical plate element, the beam apertures being configured for the passage of the source beam. A vacuum chamber, in which the emitter and the at least one charged particle optical plate element are located, the vacuum chamber being configured to maintain a pressurized source during use; and A pump is configured to remove gas from the vacuum chamber in order to maintain a pressurized source within the vacuum chamber during use, wherein the pump is located upstream of the beam relative to the transmitter. 7. The charged particle optical module according to Clause 5 or 6, wherein the charged particle optical plate element or each charged particle optical plate element defines a vent, the vent being configured to provide gas flow through the charged particle optical plate element in order to maintain a vacuum within the charged particle optical module. 8. The charged particle optical module according to any one of clauses 3, 4 and 7, wherein the vent is configured such that the operation of the pump draws gas through the vent. 9. A charged particle optical module according to any one of clauses 1 to 4, 7 and 8, wherein the vents defined in the various charged particle optical elements are aligned relative to the emitter. 10. The charged particle optical module according to any one of clauses 1 to 4 and 7 to 9, wherein the plurality of vents are defined in each charged particle optical plate element. 11. The charged particle optical module according to Clause 10, wherein at least one vent is located at an equidistant from at least two other vents. 12. A charged particle optical module according to any one of clauses 1 to 4 and 7 to 11, comprising a plurality of emitters configured to emit source beams of charged particles along respective beam paths, wherein at least one vent in the vents is substantially equidistant between adjacent beam paths. 13. The charged particle optical module according to any of the preceding clauses includes a plurality of emitters configured to emit a source beam of charged particles along a respective beam path. 14. The charged particle optical module according to Clause 12 or 13, wherein the emitters are arranged in an array. 15. The charged particle optical module according to any one of clauses 12 to 14, wherein the emitter is disposed at the emitting surface of the emitter layer. 16. A charged particle optical module according to any one of Clauses 12 to 15, wherein a plurality of said emitters are configured to emit charged particles to form the same source beam. 17. The charged particle optical module according to any of the preceding clauses, comprising: A differential vacuum arrangement, wherein the vacuum chamber is included within an outer vacuum chamber. 18. The charged particle optical module according to Clause 17, wherein the external vacuum chamber is configured to maintain a pressure higher than that of the pressurized source during use. 19. The charged particle optical module according to any of the preceding clauses, wherein the emitter is located between the pump and the beam path. 20. A charged particle optical device, comprising: Any of the charged particle optical modules described in the foregoing clauses; and An actuable stage is configured to support the sample at the sample location. 21. The charged particle optical device according to Clause 20, wherein the vacuum chamber comprises each charged particle optical device and the actuable stage. 22. An evaluation apparatus for evaluating a sample, comprising the charged particle optical device of clause 20 or 21, wherein each charged particle optical device includes at least one detector configured to detect signal particles from the sample when the sample is supported at a sample position. 23. The evaluation apparatus according to Clause 22, wherein the at least one detector comprises one or more of the electro-optical plate elements. 24. A method for manufacturing a charged particle optical module for a charged particle optical device configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: A transmitter is provided, the transmitter being configured to emit a source beam of charged particles along a source path; Defined in each of a plurality of charged particle optical plate elements configured to operate on the source beam: Beam aperture for the passage of the source beam; and A vent is configured to provide gas flow through the charged particle optical plate elements in order to maintain a vacuum within the charged particle optical module; and The transmitter and the plurality of charged particle optical plate elements are housed in a vacuum chamber configured to maintain a pressure source during use. 25. A method for manufacturing a charged particle optical module for a plurality of charged particle optical devices configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: A substrate element is provided, the substrate element including a plurality of emitters configured to emit source beams of corresponding charged particles along corresponding source paths; A plurality of beam apertures are defined in at least one charged particle optical plate element configured to operate the source beam, the plurality of beam apertures being configured for the passage of the source beam; A vent is defined in the substrate element and / or the at least one charged particle optical plate element, the vent being configured to provide gas flow through the element to maintain a vacuum within the charged particle optical module; and The transmitter and the at least one charged particle optical plate element are placed in a vacuum chamber configured to maintain a pressurized source during use. 26. The method described under Clause 24 or 25, comprising: A pump is positioned upstream of the beam relative to the transmitter, the pump being configured to remove gas from the vacuum chamber in order to maintain the pressurized source within the vacuum chamber. 27. A method for manufacturing a charged particle optical module for a charged particle optical device configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: A transmitter is provided, the transmitter being configured to emit a source beam of charged particles along a source path; In each of a plurality of charged particle optical plate elements configured to operate the source beam, a beam aperture is defined for the passage of the source beam. The emitter and the plurality of charged particle optical plate elements are housed in a vacuum chamber configured to maintain a pressure source during use; and A pump is positioned upstream of the beam relative to the transmitter, the pump being configured to remove gas from the vacuum chamber in order to maintain the pressurized source within the vacuum chamber during use. 28. A method for manufacturing a charged particle optical module for a plurality of charged particle optical devices configured to guide a beam of charged particles toward a sample location along a beam path, the method comprising: A substrate element is provided, the substrate element including a plurality of emitters configured to emit source beams of corresponding charged particles along corresponding source paths; A plurality of beam apertures are defined in at least one charged particle optical plate element configured to operate a source beam, the plurality of beam apertures being configured for the passage of the source beam; The emitter and the at least one charged particle optical plate element are housed in a vacuum chamber configured to maintain a pressurized source during use; and A pump is positioned upstream of the beam relative to the transmitter, the pump being configured to remove gas from the vacuum chamber in order to maintain the pressurized source within the vacuum chamber during use. 29. The method described under Clause 27 or 28, comprising: A vent is defined in each of the plurality of charged particle optical plate elements, the vent being configured to provide gas flow through the charged particle optical plate element in order to maintain a vacuum within the charged particle optical module during use. 30. The method according to any one of clauses 24 to 29, comprising: Align the charged particle optical plate element and (one or more) the emitter with each other. 31. The method described under Clause 30, comprising: After aligning the charged particle optical plate element and one or more of the emitters with each other, the charged particle optical module is incorporated into one or more of the charged particle optical devices.

[0143] Although embodiments of the invention may be specifically referred to herein in the context of electron microscopy, embodiments of the invention can be used in other types of apparatus. Embodiments of the invention may form part of a mask inspection apparatus, a measurement apparatus, or any apparatus for measuring or processing objects, such as wafers (or other substrates) or masks (or other patterning devices).

[0144] While specific embodiments of the invention have been described above, it should be understood that the invention can be practiced in ways other than those described. The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made to the invention as described without departing from the scope of the following claims.

Claims

1. A charged particle optical module for a charged particle optical device, the charged particle optical device being configured to guide a charged particle beam toward a sample location along a beam path, the charged particle optical module comprising: The transmitter is configured to emit a beam of charged particles along the source path; A plurality of charged particle optical plate elements are configured to operate on the source beam, wherein each charged particle optical plate element is defined as follows: A beam aperture, configured for the passage of the source beam; and A vent is configured to provide a gas flow through the charged particle optical plate element in order to maintain a vacuum within the charged particle optical module; as well as A vacuum chamber, in which the emitter and the plurality of charged particle optical plate elements are located, the vacuum chamber being configured to maintain a pressurized source during use.

2. The charged particle optical module according to claim 1, comprising: A pump is configured to remove gas from the vacuum chamber to maintain the pressurized source within the vacuum chamber.

3. The charged particle optical module according to claim 2, wherein the pump is located upstream of the beam from the emitter.

4. The charged particle optical module according to any one of claims 2 or 3, wherein the vent is configured such that the operation of the pump draws gas through the vent.

5. The charged particle optical module according to any one of claims 1 to 4, wherein the vents defined in the different charged particle optical plate elements are aligned relative to the emitter.

6. The charged particle optical module according to any one of claims 1 to 5, wherein a plurality of vents are defined in each charged particle optical plate element.

7. The charged particle optical module according to claim 6, wherein at least one vent is located at an equidistant from at least two other vents.

8. The charged particle optical module according to any one of claims 1 to 7, comprising a plurality of emitters configured to emit source beams of charged particles along respective source paths, wherein at least one of the vents is substantially equidistant between adjacent beam paths.

9. The charged particle optical module according to any one of the preceding claims, comprising a plurality of emitters configured to emit a source beam of charged particles along a respective beam path.

10. The charged particle optical module according to claim 8 or 9, wherein the emitters are arranged in an array.

11. The charged particle optical module according to any one of claims 8 to 10, wherein the emitter is disposed at the emitting surface of the emitter layer.

12. The charged particle optical module according to any one of claims 8 to 11, wherein the plurality of said emitters are configured to emit charged particles to form the same source beam.

13. The charged particle optical module according to any one of the preceding claims, comprising: A differential vacuum arrangement, wherein the vacuum chamber is included within an outer vacuum chamber.

14. The charged particle optical module of claim 13, wherein the external vacuum chamber is configured to maintain a higher pressure than the pressure source during use.

15. The charged particle optical module according to any one of the preceding claims, wherein the emitter is located between the pump and the beam path.

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