Charged-particle optical module

Abstract

The present invention relates to a charged particle optical module (200). The charged particle optical module is used for multiple charged particle optical devices configured to guide a charged particle beam along a corresponding beam path to a sample location. The charged particle optical module includes: multiple emitters (21) configured to emit a source beam of corresponding charged particles along a corresponding source path; and multiple charged particle optical plate elements (24-26) configured to act on the source beam, and wherein multiple beam apertures (266) are defined to allow the source beam to pass through, wherein at least one charged particle optical plate element (24-26) is shared by the multiple emitters, and wherein one of the planar charged particle optical elements (25) includes discrete electrodes (27) for different emitters (21) and is configured to control the current density of the corresponding source beam.

Description

Related applications

[0001] This application claims priority to EP application 24167250.0, filed on March 28, 2024, which is incorporated herein by reference in its entirety. Technical Field

[0002] This invention relates to charged particle optical modules, multiple charged particle optical devices, charged particle optical apparatuses, evaluation devices, and methods for controlling the current density of a source beam generated by a charged particle optical module. Background Technology

[0003] For example, during the manufacturing process of semiconductor integrated circuit (IC) chips or displays, undesirable defects may appear on the substrate (e.g., wafer) or mask. Such defects can reduce yield. Defects may occur as a consequence of various processes required to produce integrated circuits or displays, such as photolithography, etching, deposition, or chemical mechanical polishing. Defects can include patterning defects (where patterns are created beyond the patterning tolerances of the process) and particulate matter. Therefore, the extent to which defects are monitored during manufacturing is important. Such monitoring (or more generally, assessment) includes not only determining the presence of defects but also classifying the types of defects found.

[0004] To evaluate samples, various types of inspection or measurement systems have been used, including charged particle systems such as electron microscopes. Such evaluations for inspection may relate to defects, such as their presence and classification. Electron microscopes typically generate a probe beam (also often called a primary beam) that can scan a portion of a substrate (as in a scanning electron microscope (SEM)). The interaction products resulting from the interaction between the primary beam and the scanned portion of the substrate are collected, enabling the electron microscope to collect data representing that portion of the substrate. This data can be processed / rendered by, for example, the electron microscope to generate an image representation of that portion of the substrate. The collected data (e.g., the generated image representation) allows for the measurement of structures on that 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. Interaction products can include charged particles such as secondary electrons and backscattered electrons, which can be called signal particles (e.g., signal electrons), and can include other interaction products such as X-ray radiation.

[0005] The primary beam can be derived from the source beam emitted by the source. Multiple sources can be set up. When multiple sources are present, it can be difficult to allow the beam current of the sources to be adjusted without making the various components of the alignment source excessively difficult. It is desirable to allow the beam current to be adjusted online, while reducing the time required to perform alignment. Summary of the Invention

[0006] According to one aspect of the invention, a charged particle optical module is provided for a plurality of charged particle optical devices configured to guide a charged particle beam along a respective beam path toward a sample location. The charged particle optical module includes: a plurality of emitters configured to emit source beams of corresponding charged particles along a respective source path; and a plurality of charged particle optical plate elements configured to act on the source beam, wherein a plurality of beam apertures configured to allow the source beam to pass through are defined, wherein at least one charged particle optical plate element is shared by the plurality of emitters, wherein one of the planar charged particle optical elements includes discrete electrodes for different emitters and is configured to control the current density of the respective source beam.

[0007] According to another aspect of the invention, a charged particle optical module is provided for a plurality of charged particle optical devices configured to guide a charged particle beam along a respective beam path toward a sample location. The charged particle optical module includes: a substrate element including a plurality of emitters configured to emit a source beam of corresponding charged particles along a respective source path; and at least one charged particle optical plate element configured to act on the source beam and defining a plurality of beam apertures configured to allow the source beam to pass through. The at least one charged particle optical plate element includes discrete electrodes for different emitters and is configured to control the current density of the respective source beam.

[0008] According to another aspect of the invention, a method is provided for controlling the current density of a source beam generated by a charged particle optical module, the charged particle optical module being configured to guide a charged particle beam along a corresponding beam path toward a sample location in a charged particle optical device, the method comprising: emitting a source beam of corresponding charged particles using a plurality of emitters; applying a plurality of charged particle optical plate elements to the source beam, wherein at least one charged particle optical plate element is shared by the plurality of emitters; and controlling discrete electrodes of one of the charged particle optical plate elements for different emitters, thereby controlling the current density of the corresponding source beam.

[0009] According to another aspect of the invention, a method is provided for controlling the current density of a source beam generated by a charged particle optical module, the charged particle optical module being configured to guide a charged particle beam along a corresponding beam path toward a sample location in a charged particle optical device, the method comprising: emitting a source beam of corresponding charged particles using a plurality of emitters of a substrate element; applying at least one charged particle optical plate element to the source beam; and controlling discrete electrodes of at least one charged particle optical plate element for different emitters, thereby controlling the current density of the corresponding source beam. Attached Figure Description

[0010] Embodiments of the invention will now be described by way of example only, with reference to the accompanying schematic diagrams, wherein: Figure 1 This is a schematic diagram of an exemplary evaluation device; Figure 2 Schematic depiction of, for example 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 comprising multiple sources is schematically depicted. Figure 5 schematically depicted Figure 4 A plan view of the stacked charged particle optical modules shown. Figure 6 The source of the charged particle optical module is schematically depicted; Figure 7 schematically depicted Figure 6 The image shows a charged particle optical module that includes multiple sources; Figure 8 yes Figure 7 A plan view of the charged particle optical module shown; and Figure 9 yes Figure 7 A plan view of an alternative arrangement of the charged particle optical module shown.

[0011] The accompanying drawings are schematic. In the following description of the drawings, the same or similar reference numerals refer to the same or similar parts or entities, and differences are described only with respect to individual embodiments. Although the specification and drawings are directed to electro-optical devices, it should be understood that these embodiments are not intended to limit this disclosure to specific charged particles. Therefore, throughout this document, references to electrons and terms relating to electrons can be more generally considered as references to charged particles and terms relating to charged particles, where charged particles 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

[0012] In the semiconductor industry, there is a trend (often referred to as "Moore's Law") to reduce the physical size of structures representing circuit components on substrates and / or increase 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 can be reduced and / or the packaging density can be increased 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 the electronic device. Improving the overall yield of the manufacturing process is desirable. For example, to achieve a 75% yield in a 50-step manufacturing process (where steps can represent the number of layers formed on the substrate), each individual step must have a yield greater than 99.4%. If individual steps have a yield of 95%, the overall yield of the manufacturing process will be as low as 7-8%. Rapid defect identification is desired to maintain high substrate throughput, which is limited to the number of substrates processed per hour.

[0013] Figure 1 This 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 using one or more electron beams. The sample can be, for example, a semiconductor substrate, a substrate made of other materials, or a mask. Electrons interact with the sample and generate interaction products. Interaction products include signal electrons (e.g., 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 that can be generated. For clarity, the following description focuses on embodiments where the detected interaction product is signal electrons. For example, during operation, the evaluation apparatus 100 can include a single beam or multiple beams (i.e., multiple beams). The component beams of a multiple beam can be referred to as sub-beams or beam waves. Multiple beams can be used to simultaneously scan different portions of the sample. When the evaluation apparatus 100 uses multiple beams, it can evaluate the sample more quickly than when it uses a single beam. For example, compared to using a single-beam device, a multi-beam evaluation device can achieve a higher throughput of sample evaluation.

[0014] Figure 1The evaluation apparatus 100 includes a vacuum chamber 110, a feed lock 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 optical equipment (described in more detail below) and an actuable stage. It should be understood that references to electron optical elements of the electron optics unit 140 in the description may be considered as references to the electron optical equipment itself.

[0015] EFEM 130 includes a first feed port 130a and a second feed port 130b. EFEM 130 may include additional feed ports. For example, the first feed port 130a and the second feed port 130b may receive a substrate front-opening transfer cassette containing a sample. One or more robotic arms (not shown) within EFEM 130 transfer the sample to the feed lock chamber 120.

[0016] The feed lock chamber 120 is used to remove gas surrounding the sample. The feed lock chamber 120 can be connected to a feed lock vacuum pump system (not shown) that removes gas particles from within the feed lock chamber 120. Operation of the feed lock vacuum pump system allows the feed lock chamber to reach a first pressure below atmospheric pressure. A vacuum chamber 110 is connected to a main chamber vacuum pump system (not shown), which can be the main chamber of the evaluation apparatus 100. The main chamber vacuum pump system removes gas molecules from the vacuum chamber 110, causing the pressure around the sample to reach a second pressure equal to or below the first pressure. Different sections of the electron optics device 140 can have different levels of pressure below atmospheric pressure. After the required pressure is reached, the sample exits the feed lock chamber 120 and is transferred to the electron optics device 140 where the sample can be evaluated. The electron optics device 140 can be used for evaluation using a single beam or multiple beams. Alternatively, an array of electro-optical devices comprising multiple electro-optical devices may be used, further referred to as a multi-column electro-optical array, wherein, for example during operation, each electro-optical device (or each column in a multi-column array) comprises a single beam or multiple beams.

[0017] 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 on datasets (e.g., signals implemented as such as detection signals). Controller 150 may therefore include processing circuitry configured to perform processing functions on signals, images, and other data generated in evaluation device 100. Although controller 150 is... Figure 1The controller 150 is shown as being located outside the structure comprising the vacuum chamber 110, the feed lock chamber 120, and the EFEM 130; however, it should be understood that the controller 150 may be part of this structure. The controller 150 may be located in one component of the evaluation apparatus 100, or the controller 150 may be distributed across at least two components.

[0018] Figure 2 This is a schematic diagram illustrating an exemplary electro-optical device 140. The electro-optical device 140 can be configured as follows: Figure 1 This is part of the evaluation apparatus 100. 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 column). 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.

[0019] 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 beam waves). Electron optics device 230 can be configured to guide the primary beams 211, 212, 213 along corresponding beam paths to the sample position of sample 208. Although three beams are illustrated, the number of beams can be on the order of hundreds or thousands, for example, up to 20,000 per electron optics device 140. Multiple beams can be collectively referred to as multiple beams or beam grids. Different beams can be arranged in a pattern relative to each other in 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 within which the primary beams 211, 212, 213 can scan while the aberrations of electron optics device 230 are preserved 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, up to 20 mm at sample 208.

[0020] Electro-optical device 230 includes a plurality of electro-optical elements positioned 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 at least one stack of electro-optical elements. Such electro-optical elements may be positioned upstream or downstream 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 can be expressed as a direction along one or more beam paths. In embodiments, some different electro-optical elements may take the form of a planar object, such as plate 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 (e.g., between adjacent plates 261). One or more beam apertures 266 may be defined in plates 261 to allow one or more beams to pass through. The beam apertures 266 can be arranged in a pattern such as a regular grid (e.g., hexagons or squares). This pattern of beam apertures 266 can be referred to as an aperture array (i.e., a two-dimensional array on the plate surface). The pattern of the beam apertures 266 can correspond to the pattern of the beams within the beam grid. The beam apertures 266 acting on different plates acting on one or more of the same beams are typically aligned.

[0021] 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 corrector arrays as described in WO 2022101072 A1 is incorporated herein by reference. One or more corrector arrays may include a specific superposition of multipole deflectors having potentials applied to individual controllable electrodes. The disclosure of multipole deflector arrays in WO2012165955 is incorporated herein by reference.

[0022] One or more electro-optical elements may include apertures for paths of multiple beams. For example, the aperture may be a macroscopic aperture for all beams. The disclosures in WO 2021156121 A1 and WO 2021204734 A1 concerning slit apertures for collimators or correctors including strip electrodes are incorporated herein by reference. One or more electro-optical elements may include one or more plate electrodes that are bent along the paths of the beam grid to serve as lens arrays, corrector arrays, and / or collimator arrays, as disclosed in European Patent Application 23211553.5, filed November 22, 2023, which is incorporated herein by reference at least in relation to the use and application of bent plate electrodes.

[0023] In the current embodiment, the electron optics device 230 can form three probe spots 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 probe spots 281, 282, and 283 within individual scanning areas of the sample 208. In response to the primary beams 211, 212, and 213 incident on the sample 208, signal electrons are generated from the sample 208, which may include secondary electrons and backscattered electrons. The secondary electrons typically have an electron energy of up to 50 eV. The 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.

[0024] 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 electro-optical device 230. For example, the detector array 240 detects signal electrons from the sample 208. The detector array 240 generates a detection signal based on the detection of the signal electrons.

[0025] 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.

[0026] Detector array 240 may include multiple detector elements, with each beam having at least one detector element. For example, a detector element may be a charge-trapping electrode (e.g., a metal plate) configured to detect at least a portion of the signal electrons. Alternatively or additionally, a detector element may include a detection diode configured to detect at least a portion of the signal electrons. Alternatively or additionally, a detector element may include a scintillator material (such as YAG) configured to convert the signal electrons into photons that can subsequently 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 values ​​or intensity values ​​of pixels in an image.

[0027] Detector array 240 can transmit detection signals (e.g., as imaging or detection signals) to controller 150 or to a signal processing system (not shown) that may be part of controller 150. Controller 150 or the signal processing system can be configured to generate an image of a corresponding scan area of ​​sample 208. Detector array 240 may be at least partially incorporated 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 a secondary electro-optical device configured to direct secondary electrons to detector array 240. In such embodiments, the secondary electro-optical device includes a beam splitter (e.g., 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. It should be noted that such beam splitters may exist within different embodiments of electro-optical device 230 with detector arrays for directing primary electrons to the sample and signal particles to detector elements of the detector array.

[0028] Controller 150 (e.g., a control system including a distributed controller) can be connected to devices such as source 201, detector array 240, electro-optical device 230, and actuable stage 209. Figure 2 The various parts (e.g., components) of the electro-optical device 140. 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.

[0029] 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, rather than an electro-optical device 140. This electro-optical device array 299 is also referred to as a multi-pillar array. Different pillars (or electro-optical devices 230) can 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.

[0030] In one 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 multiple beam apertures 266 are defined for corresponding beam paths. In another embodiment, one or more sources 201 may be shared among the multiple electro-optical devices 230 of the electro-optical device array 299. Sources may be included in a source array with different sources to generate source beams for different corresponding electro-optical devices 230.

[0031] 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.

[0032] Each electro-optical device 230 of the electro-optical device array 299 can be configured in any manner described herein. The disclosure in WO 2022008286 A1 concerning how objectives are incorporated and adapted for use in a multi-device arrangement is incorporated herein by reference. The disclosure in WO 2021165135 A1 concerning a multi-device arrangement including a collimator located at or near the intermediate focal point is incorporated herein by reference.

[0033] 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-replaceable means that an electro-optical element or group of electro-optical elements can be replaced with minimal disassembly of 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.

[0034] 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 made using microfabrication techniques. As an example only, a collimator array can be formed using MEMS fabrication techniques to make it spatially compact. As another example, a scanning deflector array can be formed using MEMS fabrication techniques.

[0035] A power supply can be configured 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.

[0036] In one embodiment, controller 150 is configured to control electro-optical device 230. Controller 150 may be configured to control the potential of electrodes applied to the lenses of electro-optical device 230.

[0037] In an embodiment, controller 150 is configured to control actuable stage 209 to move sample 208 during sample inspection. At least during sample inspection, controller 150 can cause actuable stage 209 to move sample 208 continuously along a direction, such as at a constant speed, which can be referred to as a scan. The speed of actuable stage 209 can be referred to as a movement rate. Controller 150 can control the movement of actuable stage 209 to vary the speed of movement of sample 208 relative to the beam path depending on one or more parameters. Controller 150 can control the deflection of a 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 depending on 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 direction of movement of the actuated stage 209 based on the characteristics of the evaluation process. The disclosure in EP4086933 A1 regarding a combined stepping and scanning strategy for the stage and scan deflector is incorporated herein by reference. The movement rate may include the stepping frequency and / or the stage scan rate at different times.

[0038] 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.

[0039] 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 of a plurality of corresponding electro-optical devices 230.

[0040] Figure 4 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 for a plurality of electron optics devices 230. The electron optics devices 230 can be configured to guide an electron beam along a corresponding beam path to the sample location where the sample 208 is positioned.

[0041] like Figure 4 As shown, in this embodiment, the electro-optics module 200 includes a plurality of emitters 21. Each emitter 21 can be configured to emit a corresponding source beam 202 of electrons. The source beam 202 can be emitted along a corresponding source path. The source path can be the path along which the electrons of the source beam 202 travel. Figure 4Two transmitters 21 of the corresponding source 201 are schematically shown. The two transmitters 21 are shown to facilitate explanation of 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.

[0042] 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 source 201. In an embodiment, the source 201 includes a Schottky source. Additionally or alternatively, the source 201 may include a cold field emitter.

[0043] like Figure 4 As shown, in one 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 act 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 in the source beam.

[0044] like Figure 4 As shown, in this embodiment, a plurality of beam apertures 266 are defined in the electro-optical plate elements 24 to 26. The beam apertures 266 are configured to allow the source beam to pass through. Figure 4 As shown, in this embodiment, the beam aperture 266 is aligned relative to the transmitter 21.

[0045] like Figure 4 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 act on the source beam. In another embodiment, during operation, emitter 21 is configured to emit electrons. The electrons can be extracted or accelerated by the extractor device 25 to form the source beam 202.

[0046] like Figure 4 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 4 As shown, in this embodiment, at least two of the electron optical elements 24 to 26 are shared by a plurality of transmitters 21. At least one of the electron optical elements 24 to 26 is shared by all transmitters 21 of the electron optical module 200. Alternatively, at least one of the electron optical elements 24 to 26 is shared by a subset of transmitters 21 of the electron optical module 200.

[0047] like Figure 4 As 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 4 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.

[0048] like Figure 4 As shown, in this embodiment, the electron optical plate elements 24 to 26 are substantially planar. Electron optical plate elements 24 to 26 may include a main planar surface. An electromagnetic field can be established between the surfaces facing each other. The electromagnetic field may affect the electrons in the source beam emitted by emitter 21.

[0049] Electro-optical elements 24 to 26 need not be completely flat. For example, one or more of the electron optical elements 24 to 26 may be curved, such as bowl-shaped. Such a bowl-shaped electron optical element has a plate-like shape.

[0050] In an embodiment, the extractor device 25 is configured to act independently on the source beam. 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 can be different for source beams from different emitters 21. For example, the extractor device 25 can be arranged such that the magnitude and / or shape of the electromagnetic field can be different for different source beams.

[0051] Embodiments of the present invention are intended to facilitate easier alignment of emitters and extraction electrodes of multiple sources 201. Embodiments of the present invention are also intended to reduce the time required for aligning emitters and extraction electrodes of sources 201. For example, during the assembly of the electro-optics module 200, emitters 21 can be aligned relative to extraction devices 25. Sources 201 can then be integrated into an 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 be unnecessary to align the emitter relative to the extraction electrode after the source 201 has been integrated into the electro-optics device array 299.

[0052] Embodiments of the present invention are intended to improve the accuracy of beam control over a source beam generated by multiple sources 201. By using the extractor device 25 to act individually on the source beam, the beam current of the source beam can be controlled individually. For example, multiple sources 201 with more consistent beam currents relative to each other can be provided.

[0053] Figure 5 schematically depicted Figure 4A plan view of the stack 23 of electron optical plate elements 24 to 26 shown. Figure 4 and Figure 5 As shown, in one 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.

[0054] For example, in one embodiment, the electron optics plate element includes a suppressor 24. The suppressor 24 can be shared by multiple emitters 21. The suppressor 24 can be configured to suppress any unwanted electron current. Figure 4 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 4 As shown, in this embodiment, the anode 26 is shared by multiple emitters 21. For example, Figure 4 The anode 26 shown is shared by the two sources 201 shown.

[0055] For example, Figure 4 A plurality of spacers 33 configured to space the suppressor 24 from the extractor device 25 are schematically depicted. As another example, Figures 5 to 7 A plurality of spacers 36 configured to space the suppressor 24 from the anode 26 are schematically depicted. 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.

[0056] 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 space them apart from one or more of the suppressor 24, the extractor device 25, and the anode 26.

[0057] In an embodiment, one of the electro-optical plate elements 24 to 26 includes discrete electrodes. These discrete electrodes may be for different emitters 21. The electro-optical plate element including discrete electrodes can be configured to control the current density of a corresponding source beam. By providing discrete electrodes, the current density of the source beam can be controlled individually and more accurately. For example, the current density of multiple source beams can be controlled independently of each other. For example, the current density of each individual source beam can be controlled independently of the other source beams. Alternatively, the source beams can be in multiple groups, and the current density of each group of source beams can be controlled independently of the other groups of source beams.

[0058] For example, in one embodiment, the extractor device 25 includes a plurality of discrete electrodes. The discrete electrodes may include extractors 27. The extractor device 25 may be configured to control the current density of a respective source beam. For example, the potential applied to different extractors 27 may be controlled independently of other extractors 27.

[0059] Additionally or alternatively, the anode device 26 may include discrete electrodes for different emitters 21. The anode device 26 may be configured to control the current density of a respective source beam. For example, in one embodiment, the anode device 26 includes multiple anodes. Discrete electrodes may include corresponding anodes. Discrete electrodes may be anodes. By controlling the potential applied to each anode, the current density of the respective source beam can be controlled substantially independently of each other. In another embodiment, the anode device 26 includes a common anode for all emitters 21.

[0060] Additionally or alternatively, in an embodiment, the suppressor device 24 includes a plurality of discrete electrodes. The discrete electrodes may include suppressors. In an embodiment, the controller 150 is configured to control the potential applied to each suppressor independently of the others. In an alternative embodiment, the suppressor device 24 includes a common suppressor for all emitters 21.

[0061] In embodiments, discrete electrodes (e.g., discrete electrodes of anode device 26, extractor device 25, and / or suppressor device 24) are arranged in an array. The discrete electrodes of one, more, or all of these arrays can be controlled by applying a potential. For example, the discrete electrodes can be individually controlled by applying a potential.

[0062] In one embodiment, the discrete electrodes are physically separated from each other. For example, a gap may be provided between the discrete electrodes. However, physical separation of the discrete electrodes is not necessary. In another embodiment, the discrete electrodes are physically connected to each other. The discrete electrodes are electrically isolated from each other. By providing electrical isolation between the discrete electrodes, they can be controlled independently of each other.

[0063] In one embodiment, the power source is configured to supply power to the discrete electrodes. In another embodiment, the power connector is configured to controllably connect the power source to the discrete electrodes. Alternatively, multiple power sources may be present for different discrete electrodes.

[0064] like Figure 4 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 4 As shown, in this embodiment, the tip 22 is positioned upstream of the extractor device 25. Figure 4 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., suppressor 24). Figure 4 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 an electro-optical plate element (e.g., suppressor 24) upstream of the extractor device 25.

[0065] 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 contemplated to improve the mechanical stability of a plurality of sources 201, such as electrode stacks included within a plurality of 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.

[0066] In an embodiment, spacers 33, 36 are configured to electrically isolate the electro-optical plate elements 24 to 26 from each other. For example, spacers 33, 36 may be arranged such that a gap is formed between adjacent electro-optical plate elements 24 to 26. Spacers 33, 36 may comprise an electrically insulating material, such as quartz. Spacers 33, 36 may be configured to reduce the likelihood of undesirable electrical breakdown between the electro-optical plate elements 24 to 26.

[0067] During operation of the electro-optics module 200, electro-optical elements 24 to 26 can be maintained at different potentials. For example, one or more power supplies can be electrically connected to the electro-optical elements 24 to 26. The one or more power supplies can be configured to apply a potential to each of the electro-optical elements 24 to 26. For example, the controller 150 of the electro-optical device 140 can be configured to control one or more power supplies, thereby controlling the potential of the electro-optical elements 24 to 26. Embodiments of the present invention are intended to reduce the possibility of unwanted electrical breakdown.

[0068] In an embodiment, spacers 33 and 36 are configured to mechanically support the extractor device 25 in position 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 corresponding source beam emitted from the respective transmitter 21. In an embodiment, spacers 33 and 36 are configured to mechanically support the extractor device 25 in position individually relative to the beam path of the source beam, such that the extractor device 25 is configured to act 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 affect the source beam differently for different source beams. Embodiments of the present invention are expected to improve the accuracy of beam control of a corresponding source beam.

[0069] In an embodiment, the extractor device 25 includes a plurality of extractor electrodes 27, such as... Figure 4 As shown. In Figure 4 In the arrangement shown, each emitter 21 of the extractor device 25 includes an extractor electrode 27. The extractor electrodes 27 may be arranged in the same plane as each other. The extractor device 25 may be formed into a layer including a plurality of extractor electrodes 27.

[0070] like Figure 4 As shown, in this embodiment, the spacer 33 is configured as a mechanical support for the extractor device 25. For example, as... Figure 4 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 may be fixed to the downstream end of the spacer 33. The upstream end of the spacer 33 may be fixed to the suppressor 24. In another 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 size of the spacer 33.

[0071] like Figure 5As 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.

[0072] like Figure 5 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-shaped extractor device 25 relative to the transmitter 21 can be controlled. By providing three spacers 33, the plane of the extractor device 25 for each source beam can be controlled. Figure 5 As shown, in one embodiment, only three spacers 33 are configured to mechanically support the extractor device 25 for each source bundle. In another embodiment, more than three spacers 33 are provided to mechanically support the extractor device 25 for each source bundle.

[0073] like Figure 5 As shown, in this embodiment, the spacers 33 are uniformly distributed circumferentially around the source path of each source bundle. In the case where more than three spacers 33 are provided for each source bundle, in this embodiment, the spacers 33 are arranged to be uniformly distributed circumferentially around the source path.

[0074] For example, such as Figure 4 and Figure 5 As shown, in one embodiment, the extractor device 25 includes a plurality of extractor electrodes 27. Figure 5 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 5 In the arrangement shown, there are three extractor electrodes 27. In an alternative embodiment, 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.

[0075] like Figure 5As shown, in this embodiment, each extractor electrode 27 is configured to act on a different source beam. For example, each extractor electrode 27 can be configured to act on a different source beam separately. By setting different extractor electrodes 27, the extractor electrodes can be controlled individually. 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.

[0076] like Figure 5 As shown, in this embodiment, each extractor electrode 27 has multiple spacers 33. For example, each extractor electrode 27 may have three spacers, such as... Figure 5 As shown in the diagram. 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 effect of the extractor electrode 27 on the source beam can be controlled more precisely and reliably.

[0077] like Figure 4 As shown, for example, in one embodiment, spacer 33 is substantially planar. For example, spacer 33 can be disc-shaped. However, it is not necessary for spacer 33 to be substantially planar. For example, spacer 33 can have a dimension along the source path larger than its cross-beam path dimension. Figure 7 In the orientation, the spacer 33 may have a height that is at least equal to or greater than its width.

[0078] In one embodiment, spacer 33 is substantially parallel to one or more electron optical plate elements 24 to 26. For example, spacer 33 may be substantially parallel to suppressor 24. In one embodiment, spacer 33 is substantially parallel to extractor device 25 (e.g., parallel to extractor electrode 27 of extractor device 25). In one embodiment, spacer 33 is substantially parallel to anode 26.

[0079] like Figure 5 As shown, in this embodiment, the spacers 33 have substantially similar shapes in at least two dimensions. For example, in a plan view, the spacers 33 may be circular. Alternatively, for example, in a plan view, the spacers 33 may be square or hexagonal. A plan view refers to a view along the source path of the source bundle. In this embodiment, the spacers 33 have substantially similar shapes in cross-section. In this embodiment, the spacers 33 are substantially the same size in the direction transverse to the source path.

[0080] like Figure 4As shown, in this embodiment, spacers 33 and 35 have edge profiles. 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 radially located outside the radially inner portion 34. The radially inner portion 34 and the radially outer portion 35 may be formed integrally with each other.

[0081] like Figure 4 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 edge profiles.

[0082] like Figure 4 As shown, for example, in one 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, 36. The radially outer portion 35 may be fixed to only one of the two electro-optical plate elements 24 to 26 spaced apart by spacers 33, 36. Figure 7 As shown, in this embodiment, the radially outer portion 35 is fixed only upstream of the two electro-optical plate elements of which spacers 33 and 36 are configured to be spaced apart. For example, spacer 33 may have its radially outer portion 35 fixed only to suppressor 24. The radially outer portion 35 of spacer 33 may be spaced at a distance from extractor electrode 27 of extractor device 25. Spacer 36 may have a radially outer portion 35 fixed only to suppressor 24. The radially outer portion 35 of spacer 36 may be spaced at a distance from anode 26.

[0083] like Figure 4 As shown, for example, in one embodiment, the edge profile has a path length on the surface of the edge that is greater than the thickness of the spacers 33, 36. By setting the edge profile, the possibility of unwanted electrical breakdown occurring between the spaced-out electro-optical plate elements can be reduced.

[0084] like Figure 4 As shown, in one embodiment, the edge profile includes a step. The step provides an abrupt change in the size of the spacers 33, 36 in the cross-source path direction. However, having a step portion in the edge profile is not mandatory. In another embodiment, the edge profile may include a gradual change in the size of the spacers 33, 36 in the cross-source path direction. By providing a step in the edge profile, the spacers 33, 36 may have stepped edges.

[0085] In one embodiment, the extractor device 25 includes an extractor electrode 27 shared by multiple source beams. For example, Figure 4 The extractor electrodes 27 shown can, for example, be joined together to form a single integral plate. The resulting extractor electrodes can be shared by multiple source beams. By providing extractor electrodes 27 shared by 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.

[0086] In an embodiment, the extractor device 25 includes a plurality of extractor electrodes 27, each extractor electrode 27 being configured to act on a selection of a plurality of source beams. For example, each extractor electrode may be configured to act on different plurality of source beams. In an embodiment, the extractor electrodes 27 are configured to act on a corresponding source beam. For example, the extractor electrodes may be configured to act on different individual source beams. The extractor electrodes 27 may be individually controlled. 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 different extractor electrodes 27 may be controlled independently of each other.

[0087] like Figure 4 and Figure 5 As shown, in one embodiment, a vent 46 is defined within one or more of the electro-optical elements 24 to 26. The vent 46 is separate from the beam aperture 266 defined in the electro-optical elements 24 to 26. In another embodiment, multiple vents 46 are defined within one or more of the electro-optical elements 24 to 26.

[0088] like Figure 5 As shown, in this embodiment, the vents 46, defined in 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, the one shown closest to... Figure 5 The three vents 46 at the center of the stack 23 shown are aligned along the direction of the source path in both the suppressor 24 and the anode 26. In an embodiment, one or more vents 46 extending only partially through the stack 23 are provided. For example, as Figure 7 As shown, the vent 46, located on the right side of the attached figure, is confined within the suppressor 24 but is not aligned with the corresponding vent in the anode 26. The vent may be referred to as a vent hole.

[0089] In an embodiment, the vent 46 is configured to provide gas conduction through the electro-optical plate elements 24 to 26. It is not necessary for each electro-optical plate element to have at least one vent defined therein. For example, as... Figure 7As 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 conduction through the stack 23 can be increased. The gas conduction can be increased by providing some gas conduction through the beam aperture 266 compared to if only the beam aperture 266 were provided for gas conduction.

[0090] In this embodiment, gas conduction is used to maintain a vacuum within the electro-optics module 200. For example, in this embodiment, the pressure within the electro-optics module 200 is maintained at a lower level than the pressure in one or more spaces within the electro-optics device 140 outside the electro-optics module 200. Increased gas conduction through the stack 23 may be desirable to maintain the low pressure.

[0091] like Figure 4 As shown, in one embodiment, the electro-optics module 200 includes a condenser array 231. In this embodiment, the 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, during assembly of the electro-optics module 200, the condenser array 231 can be fixed to the stack 23 of the electro-optics modules 200. Before the electro-optics module 200 is incorporated into the electro-optics device 230 or the electro-optics apparatus 140, the condenser array 231 can be fixed relative to the emitter 21. Alternatively, the condenser array 231 can be omitted from the electro-optics module 200. After the electro-optics module 200 has been incorporated into the electro-optics device 230 or the electro-optics apparatus 140, the condenser array 231 of the electro-optics device 230 can be fixed relative to the emitter 21.

[0092] like Figure 4 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 for securing respective concentrator arrays 231 to respective emitters 21.

[0093] like Figure 4 As shown, in this embodiment, the concentrator array 231 is fixed to the downstream element of the stack 23. For example, as... Figure 4As 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.

[0094] like Figure 4 As shown, in this embodiment, the electron optics module 200 includes one or more electron absorbers 41, 42. For example, electron absorber 41 may be disposed on the surface of anode 26. For example, electron absorber 41 may be disposed on the upstream surface of anode 26. In this embodiment, electron absorber 42 is disposed on the surface of extractor device 25. For example, electron absorber 42 may be positioned on the downstream surface of extractor device 25.

[0095] like Figure 4 As shown, in this embodiment, an electron absorber 41 is disposed at an anode 26 corresponding to each emitter 21. An electron absorber 42 may be disposed at an extractor device 25 of each emitter 21. In this embodiment, when viewed in a plan view (i.e., along the source path), the electron absorbers 41, 42 are formed to substantially surround the source path. For example, the electron absorbers 41, 42 may form a ring.

[0096] In one embodiment, one or more electron absorbers are disposed on the upstream surface of the extractor device. In another embodiment, one or more electron absorbers are positioned on the downstream surface of the suppressor 24.

[0097] In this embodiment, electron absorbers 41 and 42 are configured to reduce the current of electrons radially outward from the source path. It is not necessary for electron absorbers 41 and 42 to be formed in a ring shape. In an alternative arrangement, when viewed in a plan view (i.e., along the beam path), electron absorbers 41 and 42 may include multiple arcuate or elongated portions.

[0098] like Figure 4 As shown, in this embodiment, the groove 49 can be disposed on the surface facing (or opposite) the electron absorbers 41, 42. For example, the groove 49 is disposed in the downstream surface of the extractor device 25 opposite to the electron absorber 41. Similarly, the groove 49 is disposed on the upstream surface of the anode 26, opposite to the electron absorber 42 disposed on the downstream surface of the extractor device 25. By providing the groove, the gap size between adjacent electron optical plate elements can be made more consistent along the beam-crossing path. By making the gap size more consistent, the electric field strength can be more consistent. Undesirable peaks in the electromagnetic field amplitude can be reduced. By avoiding high peaks in the electromagnetic field amplitude, the possibility of undesirable electrical breakdown can be reduced.

[0099] By reducing the radially outward electron current from the source path, the likelihood of unwanted charging of components in the source module 200 can be reduced. For example, the likelihood of unwanted charging of spacers 33 and 36 can be reduced. By reducing the charging of components including spacers 33 and 36, the possibility of unwanted electrical breakdown can be reduced.

[0100] like Figure 4 As shown, for example, 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 into the electro-optical device 140 or the electro-optical apparatus 230. Further alignment may be performed to align the electro-optical module 200 relative to other electro-optical elements of the electro-optical device 230 or the electro-optical device 140.

[0101] Embodiments of the present invention may be methods for providing a source beam for a plurality of electro-optical devices 230. The method may include individually adjusting the position of the emitter 21 relative to the extractor device 25. For example, a partial shape of the extractor device 25 may be adjusted. Additionally or alternatively, the extractor device 25 may be shaped under thermal load during operation. Under the thermal load applied during operation, the extractor electrodes 27 included in the extractor device 25 may act individually on the source beam.

[0102] In an embodiment, source 201 includes an avalanche diode structure. The avalanche diode structure includes a stack of doped semiconductor junctions and is biased by 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 semiconductor stacks with different bandgap values. In an embodiment, the avalanche diode structure includes a heterojunction of a silicon carbide P-type substrate and a gallium nitride N++ layer thereon. Gallium nitride has a low work function (approximately 1 eV lower), and therefore more electrons can escape from gallium nitride. Meanwhile, silicon carbide has high thermal conductivity and the ability to be fabricated as a P-type. The bandgap structure affects the electron energy distribution within 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 perpendicular to the surface facing sample 208. In the avalanche region, some electrons are sufficiently excited to overcome the work function of the surface and are emitted into the vacuum.

[0103] Figure 6 The source 201 of the electro-optics module 200 is schematically depicted, wherein the source includes an avalanche diode structure. The electro-optics module 200 may include multiple sources 201. The electro-optics module 200 may have features as described above with reference to other figures, except for the differences described below.

[0104] For ease of explanation, Figure 6 Only one source, 201, is shown. Figure 7 The schematic depiction includes multiple sources 201. Figure 6 The electro-optical module 200. Sources 201 can be included in the array. Each source 201 corresponds to a transmitter 21.

[0105] like Figure 6 As shown, in this embodiment, each source 201 includes a transmitter 21. The transmitter 21 is configured to emit an electron beam along a source path. Figure 6 In the orientation shown, the source path extends vertically upwards from transmitter 21. Figure 7 In the orientation shown, the source path extends vertically downwards from transmitter 21.

[0106] like Figure 6 As shown, in an embodiment, the electron optics module 200 includes a substrate element 84. The substrate element 84 may be planar. The substrate element 84 may be formed as a layer. For example, the electron optics module 200 may include a base substrate 83. The base substrate 83 may include silicon. For example, the base substrate 83 may be a SiC substrate. In an embodiment, the substrate element 84 is formed on the base substrate 83 by epitaxy (e.g., molecular beam epitaxy).

[0107] like Figure 6 As shown, in one embodiment, substrate element 84 includes a transmitter 21. In another embodiment, substrate element 84 also includes one or more electrical connections. These electrical connections may be for transmitting control signals and / or electrical power. The electrical connectors may be formed as traces within substrate element 84. In another embodiment, the electrical connections include electrical conductors such as metals, for example, copper.

[0108] In this embodiment, the emitter 21 is formed from a PN junction. The region of the emitter 21 may correspond to a highly p-doped region 87 of the PN junction. The highly p-doped region 87 has a higher doping concentration than the substrate element 84. In this embodiment, the substrate element 84 is a p-doped layer.

[0109] like Figure 6 As shown, in an embodiment, source 201 includes an extractor 27, which may be referred to as an extractor electrode. The extractor 27 may correspond to an emitter 21. In an embodiment, the electro-optics module 200 includes a plurality of extractors 27 corresponding to a plurality of emitters 21. Figure 6 As shown, in this embodiment, the extractor 27 is spaced apart from the transmitter 21 along the source path.

[0110] like Figure 6 As shown, in this embodiment, source 201 includes an N-doped region 85. In this embodiment, the N-doped region 85 substantially surrounds the highly P-doped region 87 of emitter 21. In this embodiment, the N-doped region 85 and the highly P-doped region 87 are spaced apart. For example, as... Figure 6 As shown, a substrate element 84 of a certain volume can exist between the N-doped region 85 and the highly P-doped region 87.

[0111] like Figure 6 As shown, in this embodiment, source 201 includes a highly N-doped layer 86. Compared to N-doped layer 85, the highly N-doped layer 86 can have a higher N-doping concentration. Figure 6 As shown, in this embodiment, a highly N-doped layer is positioned between the highly P-doped layer 87 and the extractor 27. A highly N-doped layer 86 may be positioned on the surface of the substrate element 84. In this embodiment, the highly N-doped layer 86 is configured to radially transfer electrons away from the highly P-doped layer 87.

[0112] Similar to the above embodiments, Figure 6 The electro-optics module 200 shown includes a plurality of spacers 88. The spacers 88 are configured to space the substrate element 84, including the emitter 21, from the extractor 27. Figure 6 As shown, in this embodiment, in a plan view, spacer 88 substantially surrounds the source path. As explained above, spacer 88 may have an edge profile, thereby increasing the path length along the surface of spacer 88 between emitter 21 and extractor 27. For example, surface 94 may be stepped.

[0113] like Figure 6 As shown, in this embodiment, the spacer 88 comprises multiple layers 89, 90. The layers 89, 90 may have different dimensions across the source path. For example, the first layer 89, closer to the transmitter 21, may have a larger dimension across the source path. The second layer 90 on the extractor side may have a smaller dimension across the source path. The spacer 88 is arranged to reduce the likelihood of electrical breakdown between the transmitter 21 and the extractor 27.

[0114] like Figure 6 As shown, the transmitter 21 can be positioned at the transmitter surface 80 of the electro-optical module 200.

[0115] In one embodiment, the extractor 27 comprises a non-magnetic material. In another embodiment, the extractor 27 comprises a material that is not easily oxidized. For example, the extractor 27 may comprise a material other than aluminum. The extractor 27 comprises a conductive material. In one embodiment, the extractor 27 comprises tungsten.

[0116] Figure 6 The circuitry for applying potentials to the transmitter 21 and the extractor 27 is schematically depicted. Figure 6 As shown, optionally, different potentials are applied to each of the extractor 27, the N-doped region 85, and the highly P-doped region 87. In an embodiment, electrical connections connect one or more of the highly P-doped region 87, the N-doped region 85, and the extractor 27 to one or more power sources via a substrate element 84. In an embodiment, power source 91 applies a potential difference between the highly P-doped region 87 and the N-doped region 85. A second power source 92 may apply a potential difference between the N-doped region 85 and the extractor 27. In an embodiment, the N-doped region 85 serves as the anode. In an embodiment, a common potential is applied to multiple N-doped regions 85. Different potentials may be applied to the extractors 27 corresponding to different emitters 21.

[0117] Extractor 27 can be included in the extractor device as an electro-optical plate element. In embodiments, electro-optical module 200 includes one or more additional electro-optical plate elements. For example, although Figure 7Not shown, but in embodiments, the electro-optics module 200 includes a beam-limiting aperture array and / or a single-beam corrector array. In embodiments, the beam-limiting aperture array and / or single-beam corrector array may be shared by multiple (optionally all) transmitters 21.

[0118] Figure 8 schematically depicted Figure 7 A plan view showing the arrangement of the electron optics module 200. (See diagram below.) Figure 8 As shown, in this embodiment, the extractors 27 are physically separated from each other. When viewed in a plan view, each extractor 27 substantially surrounds the emitter 21. Spacers 88 may be exposed between the extractors 27.

[0119] like Figure 8 As shown, in one embodiment, the extractor 27 has a generally circular outer perimeter. However, the outer perimeter of the extractor 27 does not have to be circular. In another embodiment, the outer perimeter is elliptical or polygonal (e.g., triangular, square, etc.). Figure 9 (as shown), pentagonal or hexagonal. For example... Figure 8 As shown, in one embodiment, the extractor 27 has a substantially circular inner perimeter. However, the inner perimeter does not have to be circular. In another embodiment, the inner perimeter of the extractor 27 is elliptical or polygonal (e.g., triangular, square, pentagonal, or hexagonal).

[0120] like Figure 8 As shown, in this embodiment, the extractors 27 are arranged in an array. In this embodiment, the array forms a grid. Figure 8 As shown, in this embodiment, the grid can be a hexagonal grid. Alternatively, the grid can be a square or rectangular grid.

[0121] Figure 9 An alternative arrangement of the extractor 27 is shown. Figure 9 In the embodiment shown, the extractor 27 has a generally rectangular outer perimeter.

[0122] like Figure 3 As shown, in this embodiment, the plurality of electro-optical devices 230 may include an electro-optical module 200. The electro-optical module may be configured to generate a source beam for the electro-optical devices 230.

[0123] In an embodiment, each electro-optical device 230 includes an electro-optical element downstream of the electro-optical module 230. The electro-optical element of the electro-optical device 230 may be configured to act on a source beam. The electro-optical element may be configured to act on a primary beam derived from the source beam generated by the electro-optical module 200.

[0124] In this embodiment, the electro-optical elements of the electro-optical device 230 are configured to act on a corresponding source beam or a primary beam derived from a corresponding source beam. Alternatively, the electro-optical elements may be configured to act on multiple source beams or primary beams derived from multiple source beams. Each electro-optical device 230 may have a source 201. Alternatively, each electro-optical device 230 may have multiple sources 201. Alternatively, the primary beams of 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.

[0125] 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 208 is supported at the sample location, 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 electro-optical plate elements. The detector interacts with electrons, allowing it to be considered an electro-optical element.

[0126] The following numbered clauses describe further embodiments of the invention: 1. A charged particle optical module for use with a plurality of charged particle optical devices configured to guide a beam of charged particles along a corresponding beam path toward a sample location, the charged particle optical module comprising: Multiple emitters, the multiple emitters being configured to emit source beams of corresponding charged particles along corresponding source paths; and A plurality of charged particle optical plate elements are configured to act on the source beam, and wherein a plurality of beam apertures are defined for the source beam to pass through, wherein at least one of the charged particle optical plate elements is shared by a plurality of emitters. One of the planar charged particle optical elements includes discrete electrodes for different emitters and is configured to control the current density of the corresponding source beam. 2. A charged particle optical module for use with a plurality of charged particle optical devices configured to guide a beam of charged particles along a corresponding beam path toward a sample location, the charged particle optical module comprising: Substrate elements, the substrate elements 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 act on the source beam, and wherein a plurality of beam apertures are defined for the source beam to pass through. The at least one charged particle optical plate element includes discrete electrodes for different emitters and is configured to control the current density of the corresponding source beam. 3. The charged particle optical module according to Clause 1 or 2, wherein the discrete electrode includes an extractor. 4. The charged particle optical module as described in Clause 3, wherein the discrete electrode is an extractor. 5. The charged particle optical module according to any of the preceding clauses, wherein at least one of the discrete electrodes is used for a plurality of the emitters. 6. The charged particle optical module according to any of the preceding clauses, wherein the emitter is arranged in an array. 7. The charged particle optical module according to any of the preceding clauses, wherein the discrete electrodes are arranged in an array. 8. The charged particle optical module according to any of the preceding clauses, wherein the discrete electrodes can be controlled by applying a potential. 9. The charged particle optical module according to Clause 8, wherein the discrete electrodes can be individually controlled by applying a potential. 10. The charged particle optical module according to any of the preceding clauses, wherein the discrete electrodes are physically separated from each other. 11. The charged particle optical module according to any of the preceding clauses, comprising: A power source, configured to supply power; and A power connector configured to controllably connect the power supply to the discrete electrodes. 12. The charged particle optical module according to any of the preceding clauses, wherein each charged particle optical plate element is arranged across the source path. 13. The charged particle optical module according to any of the preceding clauses includes an anode device as an element of the charged particle optical plate. 14. The charged particle optical module according to Clause 13, wherein the anode device comprises a plurality of anodes, each anode for a different emitter. 15. The charged particle optical module as described in Clause 14, wherein each anode is used for a separate emitter. 16. The charged particle optical module as described in Clause 13, wherein the anode device includes a common anode for all emitters. 17. The charged particle optical module according to any of the preceding clauses, including a suppressor device as a charged particle optical plate element. 18. The charged particle optical module according to Clause 17, wherein the suppressor device comprises a plurality of suppressors, each suppressor for a different emitter. 19. The charged particle optical module as described in Clause 18, wherein each suppressor is used for a separate emitter. 20. The charged particle optical module as described in Clause 17, wherein the suppressor device includes a common suppressor for all emitters. 21. The charged particle optical module according to any of the preceding clauses, comprising: Multiple spacers are configured to space multiple elements apart from each other. 22. The charged particle optical module according to Clause 21, wherein the spacers are configured such that the spacers are configured as mechanically supporting elements relative to each other. 23. The charged particle optical module according to clause 21 or 22, wherein the spacers are configured to electrically isolate the elements from each other. 24. The charged particle optical module according to any one of clauses 21 to 23, wherein the spacer is configured as an element that is different from the mechanical support. 25. The charged particle optical module according to Clause 24, wherein the spacer is configured to fix one of the elements to one or both of its adjacent elements. 26. The charged particle optical module according to clause 24 or 25, wherein the spacer is configured to support an independent electrode to one of two adjacent spacers. 27. The charged particle optical module as described in Clause 26, wherein the discrete electrode is an extractor. 28. The charged particle optical module according to any of the preceding clauses, wherein the spacer is configured to mechanically support the discrete electrodes. 29. The charged particle optical module according to Clause 28, wherein the spacers are configured to fix discrete electrodes relative to adjacent elements. 30. The charged particle optical module according to any of the preceding clauses, wherein the vent is defined in at least one charged particle optical plate element. 31. The charged particle optical module according to Clause 30, wherein the vent is configured to provide gas conduction through charged particle optical plate elements, the gas conduction being used to maintain a vacuum within the charged particle optical module. 32. The charged particle optical module according to any of the preceding clauses, comprising: A frame configured to attach the emitter to a charged particle optical plate element. 33. The charged particle optical module according to any of the preceding clauses, wherein the beam apertures of the different charged particle optical plate elements are aligned relative to the emitter. 34. A plurality of charged particle optical devices configured to guide a charged particle beam toward a sample location along a respective beam path, said plurality of charged particle optical devices comprising the charged particle optical modules described in any of the preceding clauses. 35. A plurality of charged particle optical devices according to Clause 34, wherein each charged particle optical device includes a charged particle optical element located downstream of a charged particle optical module, the charged particle optical element being configured to act on the source beam or on a primary beam derived from the source beam. 36. The plurality of charged particle optical devices according to Clause 35, wherein the charged particle optical elements are configured to act on a respective source beam or a primary beam derived from the respective source beam, or to act on a plurality of the source beams or a primary beam derived from the plurality of the source beams. 37. A charged particle optical device, comprising: A plurality of charged particle optical devices according to any one of clauses 34 to 36; and An actuable stage, which is configured to support a sample at the sample location. 38. The charged particle optical device according to Clause 37 further includes: The vacuum chamber includes the plurality of charged particle optical devices and the actuable stage. 39. An evaluation apparatus for evaluating a sample, comprising charged particle optical devices as described in clause 37 or 38, wherein the plurality of charged particle optical devices includes at least one detector array configured to detect signal particles from the sample when the sample is supported in the sample position. 40. The evaluation apparatus according to Clause 39, wherein at least one detector array comprises one or more charged particle optical plate elements. 41. A method for controlling the current density of a source beam generated by a charged particle optics module, the charged particle optics module being configured to guide a charged particle beam along a corresponding beam path toward a sample location in a charged particle optics device, the method comprising: A source beam that emits corresponding charged particles using multiple emitters; Multiple charged particle optical plate elements are applied to a source beam, wherein at least one of the charged particle optical plate elements is shared by multiple emitters; and For different emitters, the discrete electrodes of one of the charged particle optical plate elements are controlled, thereby controlling the current density of the corresponding source beam. 42. A method for controlling the current density of a source beam generated by a charged particle optics module, the charged particle optics module being configured to guide a charged particle beam along a corresponding beam path toward a sample location in a charged particle optics device, the method comprising: A source beam of corresponding charged particles is emitted using multiple emitters on a substrate element; At least one charged particle optical plate element is applied to the source beam; and The discrete electrodes of the at least one charged particle optical plate element are controlled for different emitters, thereby controlling the current density of the corresponding source beam. 43. The method according to clause 41 or 42, wherein the control includes adjusting the potential of the different discrete electrodes. 44. The method according to Clause 43, wherein the control includes individually adjusting the potentials of the different discrete electrodes. 45. The method according to Clause 44, wherein the control includes individually adjusting the potential of different discrete electrodes for each transmitter. 46. ​​The method according to any one of clauses 41 to 45, wherein each discrete electrode acts on the source beam of a different transmitter. 47. The method according to Clause 46, wherein each discrete electrode acts on the source beam of a separate transmitter. 48. The method according to any one of clauses 41 to 47, wherein the discrete electrode is an extractor.

[0127] While specific references to embodiments of the invention may be made 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 targets such as wafers (or other substrates) or masks (or other patterning devices).

[0128] Although specific embodiments of the invention have been described above, it should be understood that the invention may be practiced in ways other than those described. The above description is intended to be illustrative and not limiting. Therefore, it will be apparent to those skilled in the art that modifications may be made to the described invention without departing from the scope of the claims set forth below.

Claims

1. A charged particle optical module for use with a plurality of charged particle optical devices configured to guide a beam of charged particles along a corresponding beam path toward a sample location, the charged particle optical module comprising: Multiple emitters, the multiple emitters being configured to emit source beams of corresponding charged particles along corresponding source paths; as well as A plurality of charged particle optical plate elements are configured to act on the source beam, and wherein a plurality of beam apertures are defined for the source beam to pass through, wherein at least one of the charged particle optical plate elements is shared by a plurality of the emitters. One of the planar charged particle optical elements includes discrete electrodes for different emitters and is configured to control the current density of the corresponding source beam.

2. The charged particle optical module according to claim 1, wherein the discrete electrode includes an extractor.

3. The charged particle optical module according to any of the preceding claims, wherein at least one of the discrete electrodes is used for a plurality of the emitters.

4. The charged particle optical module according to any of the preceding claims, wherein the discrete electrodes can be controlled by applying a potential.

5. The charged particle optical module of claim 4, wherein the discrete electrodes can be individually controlled by applying a potential.

6. The charged particle optical module according to any of the preceding claims, wherein the discrete electrodes are physically separated from each other.

7. The charged particle optical module according to any of the preceding claims, wherein each charged particle optical plate element is arranged across the source path.

8. The charged particle optical module according to any of the preceding claims, comprising an anode device as a charged particle optical plate element.

9. The charged particle optical module of claim 8, wherein the anode device comprises a common anode for all emitters in the emitter.

10. The charged particle optical module according to any of the preceding claims, comprising a suppressor device as a charged particle optical plate element.

11. The charged particle optical module of claim 10, wherein the suppressor device comprises a plurality of suppressors, each suppressor for a different emitter.

12. The charged particle optical module of claim 11, wherein each suppressor is used for a separate emitter.

13. The charged particle optical module of claim 10, wherein the suppressor device comprises a common suppressor for all emitters in the emitter.

14. The charged particle optical module according to any of the preceding claims, comprising: A plurality of spacers are configured to space a plurality of elements apart from each other, wherein the spacers are configured to mechanically support the discrete electrodes, and wherein the spacers are configured to fix the discrete electrodes relative to adjacent elements.

15. The charged particle optical module according to any of the preceding claims, wherein a vent is defined in at least one charged particle optical plate element, and wherein the vent is configured to provide gas conduction through the charged particle optical plate element for maintaining a vacuum within the charged particle optical module.

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