Improved scanning deflector

Abstract

A charged particle beam system is described comprising a first electron detector, a second electron detector, and a first scanning deflector located between the first electron detector and the second electron detector, where the first scanning deflector comprises a deflector inner surface comprising a frustoconical shape.

Description

BACKGROUND

[0001] Charged particle beam systems are used for a variety of applications, including manufacturing, repairing, and inspecting micro devices, such as integrated circuits, magnetic recording heads, and photolithography masks. One type of charged particle beam system can include an electron microscope. Electron microscopes are used as a tool to image by focusing a beam of electrons of sufficient size from an electron emitter onto a focused position on a sample, and subsequently detecting signal electrons (or photons) emitted from the sample at the focused position to generate a high resolution image of the sample. SUMMARY

[0002] One aspect of the disclosure provides a charged particle beam system including a first electron detector, a second electron detector, and a first scanning deflector between the first electron detector and the second electron detector, wherein the first scanning deflector includes a deflector inner surface comprising a truncated conical shape.

[0003] Implementations can additionally include one or more of the following features. The charged particle beam system can include a second scanning deflector, wherein the second electron detector is between the second scanning deflector and the first scanning deflector. The first scanning deflector can include a first end oriented toward the first electron detector and a second end oriented toward the second electron detector, and the first end can have a first diameter and the second end has a second diameter different from the first diameter. The second diameter can be greater than the first diameter. The deflector inner surface can define a first slope from the first end to the second end, and the drift section can include a drift inner surface defining a second slope from the second end to the second electron detector, the second slope being substantially the same as the first slope. The system can include a beam column, wherein the first electron detector, the second electron detector, and the first scanning deflector can be in the beam column. The beam column can include a booster tube, and the first scanning deflector, the first electron detector, and the second electron detector are in the booster tube or are located around a length of the booster tube. The charged particle beam system can include a sample chamber including a sample holder having a sample bias. The first electron detector can be a backscattered electron detector configured to measure a first current of backscattered electrons, and the second electron detector is a secondary electron detector configured to measure a second current of secondary electrons.

[0004] Another aspect of the disclosure provides a charged particle beam system including a first electron detector, a second electron detector, and a first scanning deflector between the first electron detector and the second electron detector. The first scanning deflector includes a first end having a first diameter and a second end having a second diameter greater than the first diameter, and the first end is oriented toward the first electron detector and the second end is oriented toward the second electron detector.

[0005] Implementations can include one or more of the following features. The first scan deflector can include a deflector inner surface that includes a frustoconical shape. The system can include a second electron detector, where the second electron detector can be located between the second scan deflector and the first scan deflector. The system can include a drift section extending from the second end to the second electron detector, where the deflector inner surface of the first scan deflector can define a first slope from the first end to the second end, and the drift section can include a drift inner surface that defines a second slope from the second end to the second electron detector, the second slope being substantially the same as the first slope. The system can include a beam column, where the first electron detector, the second electron detector, and the first scan deflector are located in the beam column. The beam column can include a booster tube, and the first scan deflector, the first electron detector, and the second electron detector are located in the booster tube or around a length of the booster tube. The charged particle beam system can include a sample chamber including a sample holder having a sample bias. The first electron detector can be a backscattered electron detector configured to measure a first current of backscattered electrons, and the second electron detector is a secondary electron detector configured to measure a second current of secondary electrons.

[0006] Another aspect of the disclosure provides a charged particle beam use method that emits an electron beam from an electron source through a beam column to a sample holder in a sample chamber. The beam column includes a first electron detector, a second electron detector, and a first scan deflector located between the first electron detector and the second electron detector, where the first scan deflector includes a deflector inner surface that includes a frustoconical shape. The method also includes detecting a first portion of signal electrons emitted from the sample chamber with the first electron detector, and detecting a second portion of signal electrons emitted from the sample chamber with the second electron detector. The method also includes generating an image based on the first portion of electrons and the second portion of electrons.

[0007] Implementations can include one or more of the following features. In the method, the first electron detector can be a backscattered electron detector configured to measure a first current of backscattered electrons, and the second electron detector is a secondary electron detector configured to measure a second current of secondary electrons. The beam column can include a second scan deflector, and the second electron detector is located between the second scan deflector and the first scan deflector. BRIEF DESCRIPTION OF DRAWINGS

[0008] A further understanding of the nature and advantages of various implementations can be realized by reference to the following drawings. In the drawings, like reference numerals can designate similar structures or features. Also, various components can be distinguished by consistent use of first, second, third, and / or other designations. Similarly, features can be distinguished by consistent use of designators, e.g., 100, 200, 300, etc. for structural elements, and / or 110, 210, 310, etc. for process instances, regardless of type or specific from of designator. Unless specifically stated otherwise, as appreciated by one of ordinary skill in the art, references to one alternative list a feature can include all other possible combinations for implementing the feature.

[0009] Figure 1 A simplified cross-sectional view of an exemplary charged particle beam system is depicted.

[0010] Figure 2A A simplified cross-sectional view of an exemplary charged particle beam system is depicted.

[0011] Figure 2B A simplified cross-sectional view of an exemplary charged particle beam system is depicted. Figure 2A A charged particle beam system according to embodiments of the present disclosure measures signal electrons emitted from a sample.

[0012] Figure 3 A flowchart of generating an image based on signal electrons emitted from a sample according to embodiments of the present disclosure is depicted.

[0013] Figure 4 A block diagram of an exemplary computer system usable with systems and methods according to embodiments of the present disclosure is depicted. DETAILED DESCRIPTION

[0014] Charged particle beam systems used in electron microscopes provide high resolution imaging by detecting signal electrons (e.g., backscattered electrons, secondary electrons, etc.) that are produced by elastic scattering of an electron beam that is emitted from an electron emitter and that interacts with atoms of a sample. In one example, the electrons can be emitted from a current heated cathode electrode. The emitted electrons are attracted to an anode that is positioned downstream of the cathode electrode, thereby forming an electron beam that is directed at and interacts with the sample. The signal electron current that is emitted from the electron beam that interacts with the sample is measured by one or more electron detectors. This current can be used to generate a high resolution image of the sample.

[0015] Some example charged particle beam systems can include a scanning deflector in the beam column that can generate a deflection field (e.g., an electric field or an electromagnetic field) intended to deflect the electron beam as it travels through the beam column. However, the trajectory of signal electrons that are emitted from the sample back into the beam column (e.g., toward the scanning deflector) can be altered by this deflection field. Due to the geometry of the scanning deflector, this altered trajectory can cause the signal electrons to collide with certain portions of the scanning deflector. For example, a lower scanning deflector can define an inner surface having a cylindrical shape. However, signal electrons emitted from the sample at an angle relative to the electron beam can be blocked by the inner surface of the lower scanning deflector before reaching the upper electron detector. This can cause the upper electron detector to measure only a portion of the signal electrons. In particular, since the lower scanning deflector is likely to block the outermost signal electrons, the resulting image can contain vignetting effects in which the outer edges of the image appear different from the central portion of the image (e.g., an image of a uniform specimen without topographical features has a noticeable gray scale shift between the central portion and the edges). This problem can be particularly severe when attempting to create images with a large field of view (e.g., for certain workflows in semiconductor imaging).

[0016] Furthermore, in conventional charged particle beam systems, one or more scanning deflectors can be too far away from the objective lens. For example, the large distance between a lower scanning deflector (e.g., the scanning deflector closest to the objective lens in the beam column) and the objective lens can increase the likelihood of the electron beam colliding with the deflector due to the geometry of the electron beam and the deflector. In particular, the greater the distance between the deflection center of the deflector and the objective lens, the more the deflection field of the deflector will have to be excited to compensate for this distance. Since the signal electrons define a signal beam having a conical shape with a virtual apex approximately at the sample, increasing the excitation of the deflection field affects the shape of the signal beam, thereby increasing the likelihood that a portion of the signal beam intersects the deflector (e.g., due to the widening of the conical shape of the signal beam).

[0017] The present disclosure addresses this problem by providing a charged particle beam system having a lower scanning deflector that is frustoconical in shape. In particular, the end of the lower scanning deflector oriented toward (e.g., facing) the upper electron detector can have a larger diameter than the opposite end of the lower scanning deflector oriented toward (e.g., facing) the backscattered electron detector and / or the sample, thereby making it less likely that electrons passing through the lower scanning deflector will collide with the inner surface of the lower scanning deflector. Furthermore, the lower scanning deflector can be effectively moved closer to the objective lens to minimize the likelihood of the electron beam intersecting the lower scanning deflector. In this way, more signal electrons can be received by the electron detector and a large field of view image without vignetting can be generated.

[0018] While the remainder of this specification will routinely refer to a scanning electron microscope (SEM), the skilled artisan will readily understand that the technology is not so limited. The present design can be used in other types of charged particle microscopes, such as a transmission electron microscope (TEM), a scanning transmission electron microscope (STEM), a dual beam system including an ion beam source and an electron beam source, a reflection electron microscope (REM), a circuit editing microscope, etc. Thus, the present disclosure and claims should not be viewed as limited to any particular exemplary microscope under discussion, but rather can be used broadly for any number of electron microscopes that can exhibit some or all of the electrical or chemical features of the exemplary under discussion.

[0019] Figure 1 is a schematic diagram of an exemplary charged particle microscope 100 according to certain embodiments of the present disclosure. The exemplary charged particle microscope 100 includes a plurality of sections, including an electron source 102, a beam column 105, and a sample chamber 110. The electron source 102 includes a high voltage power supply component, a vacuum system component, and an electron emitter configured to generate an electron beam that is accelerated into the beam column 105. The beam column 105, in turn, can include electromagnetic lens elements and / or diaphragm blades 106 configured to shape the electron beam from the electron source 102 and to shape it into a substantially circular beam having a generally uniform profile transverse to the beam axis A, and to prepare the beam for focusing onto a sample 125 by an objective lens 115.

[0020] The electron beam is generally characterized by a beam current and an acceleration voltage applied to generate the beam, as well as other standards. The range of beam currents and the range of acceleration voltages can vary between instruments, and are generally selected based on the material properties of the sample or the type of analysis being performed. However, generally, the electron beam is characterized by an energy of about 0.1 keV (e.g., for an acceleration voltage of 0.1 kV) to about 50 keV, and a beam current from picoamperes to microamperes.

[0021] The sample chamber 110 and / or beam column 105 can include multiple detectors for various signals, including but not limited to signal electrons generated by electron beam and sample interaction, X-ray photons (e.g., EDAX), other photons (e.g., visible light camera and / or IR camera), and / or molecular species (e.g., TOF-SIMS). The sample chamber 110 can also include a sample holder 120 that can be operably coupled with the multi-axis translation / rotation control system 104 such that the sample 125 can be repositioned relative to the beam axis A as a method of investigating and / or imaging the sample 125. In addition, the sample holder 120 can include a hole that allows electrons or other charged particles to be transmitted through the sample and sample stage. In this way, one or more charged particle sensors (e.g., electron detectors) of the present disclosure can be disposed in the sample chamber 110 and / or beam column 105 and configured to detect signal electrons originating from the sample.

[0022] As discussed above, in conventional charged particle beam systems, one or more scanning deflectors can block the trajectories of certain signal electrons (e.g., a portion of secondary electrons). The beam column 105 can include an electron deflection system 126 that addresses this issue. In particular, the electron deflection system 126 can include one or more deflectors having a shape that minimizes the risk of the deflector blocking the trajectories of signal electrons. In addition, the electron deflection system 126 can enable one or more electron detectors to be positioned closer to the objective lens 115. For example, Figure 2A and Figure 2B An example charged particle beam system 200 and a computer system 290 (similar to the computer system 410 shown in FIG. 4) in communication with the charged particle beam system 200 to provide instructions to operate the charged particle beam system 200 are depicted. For the sake of simplicity, not all features of the charged particle beam system 200 are shown. It should be understood that features ending in similar reference numerals are similar to those discussed above unless noted otherwise below. Figure 4 The charged particle beam system 200 is shown in use and Figure 2A The charged particle beam system 200 is shown measuring signal electrons. Figure 2B The charged particle beam system 200 is shown measuring signal electrons.

[0023] Turning to Figure 2AThe beam column 205 can include an electron deflection system 226 that includes a first electron detector 230, a first scanning deflector 250, a second electron detector 240, and a second scanning deflector 270. An electron source can emit an electron beam into the beam column 205 through a column entrance 231, out of the beam column 205 through a beam exit 232, through the objective lens 215, and onto the sample 225. The first electron detector 230 can be configured to measure a first current of a first set of electrons (e.g., backscattered electrons) emitted from the sample 225 after interaction of the electron beam with the sample 225. The second electron detector 240 can be configured to measure a second current of a second set of electrons (e.g., secondary electrons) emitted from the sample 225 after interaction of the electron beam with the sample 225. The second electron detector 240 can be located upstream along the electron beam trajectory relative to the first electron detector 230. Thus, the second electron detector 240 can be an upper electron detector, and the first electron detector 230 can be a lower electron detector.

[0024] Either of the electron detectors 230, 240 can be an active detector (e.g., a semiconductor diode, an electron detector using the principle of scintillation, etc.) or a passive detector (e.g., a conductive metal plate). In some embodiments, the first electron detector 230 and the second electron detector 240 can each be the same type of detector (e.g., active or passive), although in other embodiments, the first and second electron detectors can each be a different type of detector.

[0025] The scanning deflectors 250, 270 can each generate a deflection field that directs and shapes the electron beam objective lens 215 and the sample 225. In particular, the second scanning deflector 270 can generate a first deflection force to deflect one or more portions of the electron beam emitted from the column entrance 231 (e.g., from the electron source) to flow through an aperture 242 defined by the second electron detector 240. The first scanning deflector 250 can generate a second deflection force to further deflect one or more portions of the electron beam from the second electron detector 240 to flow through an aperture 236 defined by the first electron detector 230 to the objective lens 215. The second scanning deflector 270 can be located upstream along the electron beam trajectory relative to the first scanning deflector 250. Thus, the second scanning deflector 270 can be an upper scanning deflector, and the first scanning deflector 250 can be a lower scanning deflector.

[0026] As discussed above, in conventional charged particle beam systems, at least some of the signal electrons emitted from the sample can be blocked by the first scanning deflector (e.g., the lower scanning deflector), due at least in part to the deflection field generated by the lower scanning deflector, such that only a portion of the signal electrons are measured by the upper electron detector. The shape of the first scanning deflector 250 of the present disclosure addresses this issue. Turning back to FIG. 2, the first scanning deflector 250 can be configured to generate a deflection field that directs and shapes the electron beam objective lens 215 and the sample 225. In particular, the first scanning deflector 250 can generate a first deflection force to deflect one or more portions of the electron beam emitted from the column entrance 231 (e.g., from the electron source) to flow through an aperture 236 defined by the first electron detector 230. The first scanning deflector 250 can generate a second deflection force to further deflect one or more portions of the electron beam from the first electron detector 230 to flow through an aperture 242 defined by the second electron detector 240 to the objective lens 215. The first scanning deflector 250 can be located upstream along the electron beam trajectory relative to the second scanning deflector 270. Thus, the first scanning deflector 250 can be an upper scanning deflector, and the second scanning deflector 270 can be a lower scanning deflector. Figure 2BAfter the electron beam interacts with the sample 225, first electrons 233 (e.g., backscattered electrons) are emitted from the sample 225 to be measured by the first electron detector 230, and second electrons 234 (e.g., secondary electrons) are emitted from the sample 225 to be measured by the second electron detector 240. The first scan deflector 250 defines a deflector inner surface 251 having a frustoconical shape such that the trajectory of the second electrons 234 is not blocked by the deflector inner surface 251. The first scan deflector 250 can include a first end 252 oriented toward (e.g., facing) the first electron detector 230. The first end 252 can have a first diameter dl that is less than a second diameter d2 of a second end 253 of the scan deflector 250 oriented toward (e.g., facing) the second electron detector 240. The diameters dl, d2 can be the major diameters of the ends 252, 253.

[0027] The deflector inner surface 251 can have a substantially linear deflector slope 254. However, in other embodiments, the inner surface can have other shapes, such as having a convex or concave, stepped shape, or having various bevels or curves. Further, the deflector inner surface 251 can have an angle 255 with respect to the Z-axis (e.g., an axis parallel to the electron beam axis). In some embodiments, the angle 255 can correspond to a major dimension of the second electron detector 240 and a distance of the second electron detector 240 from the first end 252. For example, the angle 255 can be the angle of a substantially straight line from the first end 252 to the major diameter of the second electron detector 240 (as shown in the cross-sectional view of FIG. 2B). In one example, the angle 255 can be between about 10° and 45°, such as between about 15° and 40°, between about 20° and 35°, or between about 25° and 30°. Figure 2B

[0028] Because the deflector inner surface 251 exhibits a frustoconical shape from the first end 252 having the first diameter dl to the second end 253 having the second diameter d2, the second electrons 234 can flow from the column exit 232 to the second electron detector 240 at a transverse angle with respect to the Z-axis without being blocked by the deflector inner surface 251. In this way, the second electron detector 240 can measure more of the second electrons 234, and can generate a more detailed image of the sample 225 (e.g., without the vignetting effect caused by conventional systems).

[0029] ​As also discussed above, because the scan deflector in conventional charged particle beam systems is distanced from the objective lens, the likelihood that the signal beam can be blocked by the deflector can increase. The first scan deflector 250 addresses this issue because the shape of the deflector inner surface 251 changes the deflection center of the first scan deflector 250 from the objective lens 215. In particular, the deflection center of the first scan deflector 250 corresponds to the strength of the deflection field generated by the first scan deflector 250, which in turn corresponds to the diameter of the deflector inner surface 251. Thus, the deflection field generated by the first scan deflector 250 is strongest at the first end 252, moving the deflection center of the first scan deflector 250 closer to the objective lens 215. Moving the deflection center of the first scan deflector 250 closer to the objective lens 215 can reduce the excitation required for the deflection field of the first scan deflector 250, thus minimizing changes (e.g., widening) to the signal beam shape defined by the second electrons 234. This in turn reduces the risk of the second electrons 234 colliding with the first scan deflector 250 (or the drift section inner surface 261).

[0030] By placing the first electron detector 240 closer to the objective lens 215 than in conventional charged particle beam systems, the vignetting effect can be further reduced. In conventional charged particle beam systems, the upper electron detector can be positioned upstream of the second scan deflector (e.g., the upper scan deflector), such that the upper scan deflector is between the upper electron detector and the objective lens. Because the upper electron detector is positioned further away and the upper scan deflector is between the upper electron detector and the objective lens, the trajectories of the secondary electrons can have a higher probability of being altered and blocked (e.g., by the upper scan deflector or other objects between the upper scan deflector and the objective lens) before reaching the upper electron detector. Thus, the position and orientation of the upper electron detector in the beam column of conventional charged particle beam systems can result in lower quality sample images, such as images with the vignetting effect.

[0031] In the charged particle beam system 200, these issues are addressed by positioning the second electron detector 240 between the second scan deflector 270 and the objective lens 215. In this way, the second electron detector 240 can be positioned closer to the objective lens 215 while also minimizing objects that can obstruct the trajectories of the second electrons 234. This can result in the second electron detector 240 measuring more of the second electrons 234, thus generating a clearer image.

[0032] It can be beneficial to provide a space (e.g., a drift section 260) between the second electron detector 240 and the second end 253 of the first scan deflector 250 to further minimize image distortion effects. This drift section 260 can compensate for the changing trajectory of the second electrons 234 due to the deflection field generated by the first scan deflector 250, such that if the second electron detector 240 were closer to the first scan deflector 250 (e.g., without the drift section 260, such that the second electron detector 240 is seated against the second end 253), the resulting image can have more vignetting effects because the changing trajectory of the second electrons 234 affects other features of the beam column 205 before reaching the second electron detector 240. However, the drift section 260 between the second scan detector 240 and the first scan deflector 250 can compensate for this trajectory change and allow the second electron detector 240 to receive more of the second electrons 234 in space. However, in other embodiments, there can be no drift section, and instead the second electron detector can be coupled against the second end of the first scan deflector. In some embodiments, the drift section 260 can be defined by an outer housing of the beam column 205. However, in other embodiments, the drift section can be defined by a separate component of the beam column.

[0033] The drift section 260 can include a drift section inner surface 261 having a drift section slope 264 that is similar in value to the deflector slope 254. For example, the drift section slope 264 and the deflector slope 254 can have about 70% the same value, about 80% the same value, about 90% the same value, or about exactly the same value. In one example, the drift section inner surface 261 can have substantially similar angles (e.g., angle 255) from the Z-axis as the deflector slope 254. For example, the drift section slope 264 and the deflector slope 254 can have about 70% the same angle, about 80% the same angle, about 90% the same angle, or about exactly the same angle. Thus, the drift section inner surface 261 can define a frustoconical shape. The shape of the drift section inner surface 261 can allow the second electrons 234 to travel from the first scan deflector 250 through the drift section 260 while minimizing the risk of the trajectory of the second electrons 234 that are traveling at a transverse angle relative to the Z-axis being blocked by other components (e.g., a more cylindrical drift inner surface). The drift section inner surface 261 can have a drift section slope 264 that is substantially linear from the second end 253 to the third end 263 of the drift section inner surface 261. However, in other embodiments, the drift section inner surface can have other shapes, such as having a convex or concave shape, a stepped shape, or having various slopes or curves. In yet other embodiments, the drift section inner surface and the deflector inner surface can each have different shapes. For example, the drift section inner surface can have a conical shape with a diameter corresponding to a major dimension of the second electron detector, while the deflector inner surface has a frustoconical shape.

[0034] The second electron detector 240 can have a dimension along the XY plane that corresponds to a diameter of the third end 263. For example, the diameter of the second electron detector 240 and the diameter of the third end 263 can have about 70% of the same value, about 80% of the same value, about 90% of the same value, or about exactly the same value. In this way, the second electron detector 240 can be more likely to measure all of the second electrons 234 that travel through the drift section 260. However, in other embodiments, the diameter of the second electron detector and the diameter of the third end of the drift inner surface can be different. For example, the diameter of the second electron detector can be greater than the diameter of the third end of the drift inner surface, or vice versa.

[0035] The electron detectors 230, 240 can be used in conjunction with various other components. For example, the electron detectors 230, 240 can be used in conjunction with a booster tube 280 in the beam column 205 or a sample bias (e.g., a sample negative bias, etc.) in the sample chamber 210. The booster tube 280 can generate an electromagnetic field to increase the kinetic energy of electrons in the beam column 205. An electrical bias can be applied to the sample holder 220 to generate an electromagnetic field that surrounds the sample holder 220 and accelerates signal electrons from the sample 225 to the beam column 205. In some embodiments, the beam column 205 can house the booster tube 280. The booster tube 280 can at least partially surround one or more components of the beam column 205. For example, the booster tube 280 can at least partially surround the first electron detector 230, the second electron detector 240, the first scanning deflector 250, the drift section 260, and the second scanning deflector 270, such that the first electron detector 230, the second electron detector 240, the first scanning deflector 250, the drift section 260, and the second scanning deflector 270 are located in the booster tube 280. In other embodiments, the scanning deflectors can be located outside or around (e.g., around a length of) the booster tube. In some embodiments, the charged particle beam system can include only one of a booster tube or a sample bias. In still other embodiments, the charged particle beam system can lack a booster tube or a sample bias.

[0036] Figure 3 An example flowchart is depicted that illustrates a process 300 of generating an image based on signal electrons emitted from a sample. It should be understood that features ending in similar reference numerals are similar to those discussed above unless otherwise noted. Unless otherwise noted, the flowchart in Figure 3 will be described with reference to the charged particle beam system 200 shown in Figure 2A and Figure 2B The following operations on the components of the charged particle beam system 200 can be performed by the computer system 290.

[0037] Block 310 can include emitting an electron beam from an electron source through beam column 205 into sample holder 220 in sample chamber 210. Beam column 205 can include first electron detector 230, second electron detector 240, and first scanning deflector 250 between first electron detector 230 and second electron detector 240. First scanning deflector 250 can include a deflector inner surface 251 that includes a truncated conical shape. For example, the electron source can emit an electron beam from a column entrance 231 through components of beam column 205, a column exit 232, objective lens 215, and toward sample holder 220 to interact with sample 225.

[0038] Block 320 can include detecting a first portion of electrons emitted from sample chamber 210 with first electron detector 230. For example, first electron detector 230 can detect backscattered electrons emitted from sample 225 after the electron beam interacts with sample 225. First electron detector 230 can measure a current of the backscattered electrons.

[0039] Block 330 can include detecting a second portion of electrons with second electron detector 240. For example, second electron detector 240 can measure a current of secondary electrons.

[0040] Block 340 can include generating an image based on the first portion of electrons and the second portion of electrons. For example, an image can be generated based on the measurements of backscattered electrons detected by first electron detector 230 and the measurements of secondary electrons detected by second electron detector 240.

[0041] Any computer system referred to herein (e.g., computer system 290) can utilize any suitable number of subsystems. Examples of such subsystems are shown in computer system 410 shown in FIG. 4. In some embodiments, a computer system includes a single computer device, where the subsystems can be components of the computer device. In other embodiments, a computer system can include multiple computer devices, each computer device being a subsystem with internal components. Computer systems can include desktop and laptop computers, tablet computers, mobile phones, and other mobile devices. Figure 4

[0042] Figure 4 The subsystems in FIG. 4 are interconnected via system bus 475. Additional subsystems such as a printer 474, keyboard 478, storage device 479, monitor 476 (e.g., a display screen) coupled to display adapter 482, and others are shown. Peripherals and input / output (I / O) devices, which can include mice and ​For example, an I / O port 477 or external interface 481 (e.g., Ethernet, Wi-Fi, etc.) can be used to connect the computer system 410 to a wide area network such as the Internet, a mouse input device, or a scanner. Interconnection via the system bus 475 permits the central processing unit 473 to communicate with each subsystem and to control the execution of instructions from the system memory 472 or the storage device 479 (e.g., a fixed or removable disk, such as a hard drive or compact disk) as well as the exchange of information between subsystems. The system memory 472 and / or the storage device 479 can embody a computer readable medium. Another subsystem is a data acquisition device 485, such as a video camera, microphone, accelerometer, etc. Any data mentioned herein can be output from one component to another and to a user.

[0043] A computer system can include multiple identical components or subsystems, e.g., connected together by external interfaces 481, by internal interfaces, or by removable storage devices that can be connected to and removed from one component to another. In some embodiments, a computer system, subsystem, or device can communicate over a network. In such cases, one computer can be considered a client and another a server, each of which can be part of the same computer system. A client and a server can each include multiple systems, subsystems, or components.

[0044] Aspects of the embodiments can be implemented using hardware circuitry (e.g., application specific integrated circuits or field programmable gate arrays) and / or using computer software stored in memory with a general purpose programmable processor, in a modular or integrated manner, in the form of control logic, and the processor can thus include memory storing software instructions that configure the hardware circuitry, as well as FPGAs or ASICs with configuration instructions. As used herein, a processor can include a single core processor, multiple core processor on the same integrated chip, or multiple processing units on a single circuit board or networked and specialized hardware. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will know and appreciate other ways and / or methods to implement embodiments of the disclosure using hardware and a combination of hardware and software.

[0045] Any of the software components or functions described in this application (e.g., process 300) can be implemented as software code to be executed by a processor using any suitable computer language such as Java, C, C++, C#, Objective-C, Swift, or scripting language such as Perl or Python using, for example, conventional techniques or object-oriented techniques. The software code can be stored as a series of instructions or commands on a computer readable medium for storage and / or transmission. A suitable non-transitory computer readable medium can include random access memory (RAM), a read only memory (ROM), a magnetic medium such as a hard-drive or a floppy disk, or an optical medium such as a compact disk (CD) or DVD (digital versatile disk) or Blu-ray, flash memory, and the like. The computer readable medium can be any combination of such devices. Further, the operating environment or elements of the process can be rearranged. The process can terminate when its operations are completed, but can also terminate without completing its operations due to, for example, system shutdown. The process can correspond to a method, function, procedure, subroutine, subprogram, etc. When the process corresponds to a function, its termination can correspond to a return of the function to the calling function or the main function.

[0046] Such programs can also be encoded and transmitted using carrier signals adapted to be transmitted via wired, optical, and / or wireless networks conforming to a variety of communications protocols, including the Internet. As such, a computer readable medium including a computer readable storage medium is any available medium or device that is enab!ed to store and / or transfer data. A computer readable storage medium can include residing on or within a single computer product (e.g., hard disk drive, CD, or the entire computer system). A computer readable storage medium can be external or internal to a system or network over which the computer readable storage medium is to be distributed. By way of example, computer readable storage media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code means in the form of computer readable instructions or data structures and that can be accessed by a computer. Computer readable storage media could even include a freely programmable processor, as in the case of quantum computers. For example, data can be downloaded into the memory of such computers from the Internet or elsewhere. Due to the world wide nature of the Internet, data downloaded from the Internet can often be considered to be in the public domain. A computer readable storage medium can be non-transitory, and can include temporary and / or removable computer readable storage media. Data structures can be stored in computer readable storage media in any suitable format ready to be accessed by a computer.

[0047] Any method described herein can be performed, in whole or in part, by a computer system comprising one or more processors configured to perform these steps. Any operation performed by the processor (e.g., alignment, determination, comparison, computation) can be performed in real time. The term "real time" can refer to a computational operation or process completed within a time limit. The time limit can be 1 minute, 1 hour, 1 day, or 7 days. Therefore, embodiments can involve a computer system configured to perform the steps of any method described herein, which may have different components performing the corresponding steps or groups of steps. Although steps are shown as numbered, the steps of the methods herein can be performed simultaneously or at different times or in different orders. Furthermore, portions of these steps can be used in conjunction with portions of other steps from other methods. Furthermore, all or part of a step can be optional. Furthermore, any step of any method can be performed using modules, units, circuits, or otherwise of a system that performs these steps.

[0048] In the foregoing description, embodiments of this disclosure have been described with reference to numerous specific details, which may vary depending on the implementation. Therefore, the description and drawings should be considered illustrative rather than restrictive. The sole and exclusive indication of the scope of this disclosure, and what the applicant intends to define as the scope of this disclosure, is the literal and equivalent scope of the claims granted in the specific form (including any subsequent amendments) published in this application. Specific details of particular embodiments may be combined in any suitable manner without departing from the spirit and scope of embodiments of this disclosure.

[0049] In addition, spatially relative terms such as “bottom” or “top” may be used to describe the relationship between one element and / or feature and another, as shown in the accompanying drawings. It should be understood that, in addition to the orientations depicted in the drawings, spatially relative terms are also intended to cover different orientations of the device during use and / or operation. For example, if the device in the drawings is flipped, an element described as the “bottom” face may be oriented “above” other elements or features. The device may be oriented in other ways (e.g., rotated 90° or in other orientations), and the spatially relative descriptors used herein can therefore be interpreted.

[0050] The terms "and", "or", and "and / or" as used herein can include a variety of meanings that also are expected to depend at least in part upon the context in which such terms are used. Typically, "or" if used to associate a list, such as A, B, or C, is intended to mean A, B, and C, here used in the inclusive sense, as well as A, B or C, here used in the exclusive sense. In addition, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular or can be used to describe some combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example and claimed subject matter is not limited to this example. Furthermore, the term "at least one" if used to associate a list, such as A, B, or C, can be interpreted in the alternative (i.e. A or B or C) or in the aggregate (i.e. A, B, and / or C). In addition, the unqualified term "or" can be used to mean "and / or" in most cases.

[0051] References throughout this specification to "one example", "an example", "certain examples" or "exemplary implementations" mean that a particular feature, structure, or characteristic described in connection with the feature and / or example can be included in at least one feature and / or example of claimed subject matter. Thus, the appearances of the phrase "in one example", "one example", "in certain examples", "in certain implementations" or other similar phrases in various places throughout this specification are not necessarily all referring to the same feature, example and / or limitation. Furthermore, the particular

[0052] In some implementations, operations or processes can involve the physical manipulation of physical quantities. Generally, although not necessarily, such quantities can take the form of electrical or magnetic signals, where the signals are capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to such signals as bits, data, values, elements, symbols, characters, terms, numbers, numerals, or the like. However, it should be understood that all of these or similar terms are to be associated with appropriate physical quantities and are merely convenient labels. Unless specifically stated otherwise, as apparent from the discussion herein, it is appreciated that throughout this specification discussions utilizing terms such as "processing", "computing", "calculating", "determining" or the like can refer to the action or processes of a specific device, such as a special purpose computer, a special purpose computing device, or a similar special purpose electronic computing device. In one

[0053] In the preceding detailed description, numerous specific details have been set forth in order to provide a thorough understanding of the claimed subject matter. However, individuals having the benefit of the present disclosure will appreciate that the claimed subject matter can be practiced without the specific details set forth in the preceding description. In other instances, well-known methods and apparatuses have not been described in detail in order to avoid obscuring the claimed subject matter. Accordingly, it is intended that the claimed subject matter not be limited to the particular examples disclosed in the preceding detailed description, but rather include all aspects that would be within the scope of the appended claims and their equivalents.

Claims

1. A charged particle beam system comprising: a first electron detector; a second electron detector; and a first scanning deflector located between the first electron detector and the second electron detector, wherein the first scanning deflector includes a deflector inner surface comprising a truncated conical shape.

2. The charged particle beam system of claim 1, further comprising a second scanning deflector, wherein the second electron detector is located between the second scanning deflector and the first scanning deflector.

3. The charged particle beam system of claim 2, wherein: the first scanning deflector includes a first end oriented toward the first electron detector and a second end oriented toward the second electron detector; and the first end has a first diameter and the second end has a second diameter different from the first diameter.

4. The charged particle beam system of claim 3, wherein the second diameter is greater than the first diameter.

5. The charged particle beam system of claim 3, further comprising a drift section extending from the second end to the second electron detector, wherein: the deflector inner surface defines a first slope from the first end to the second end; and the drift section includes a drift inner surface defining a second slope from the second end to the second electron detector, the second slope being substantially the same as the first slope.

6. The charged particle beam system of claim 1, further comprising a beam column, wherein the first electron detector, the second electron detector, and the first scanning deflector are located in the beam column.

7. The charged particle beam system of claim 6, wherein: the beam column includes a booster tube; and the first scanning deflector, the first electron detector, and the second electron detector are located in or around a length of the booster tube.

8. The charged particle beam system of claim 1, further comprising a sample chamber including a sample holder having a sample bias.

9. The charged particle beam system of claim 1, wherein the first electron detector is a backscattered electron detector configured to measure a first current of backscattered electrons and the second electron detector is a secondary electron detector configured to measure a second current of secondary electrons.

10. A charged particle beam system comprising: a first electron detector; a second electron detector; and a first scanning deflector located between the first electron detector and the second electron detector, wherein: the first scanning deflector includes a first end having a first diameter and a second end having a second diameter greater than the first diameter; and the first end is oriented toward the first electron detector and the second end is oriented toward the second electron detector.

11. The charged particle beam system of claim 10, wherein the first scanning deflector includes a deflector inner surface comprising a truncated conical shape.

12. The charged particle beam system of claim 10, further comprising a second scanning deflector, wherein the second electron detector is located between the second scanning deflector and the first scanning deflector.

13. The charged particle beam system of claim 12, further comprising a drift section extending from the second end to the second electron detector, wherein: the deflector inner surface of the first scanning deflector defines a first slope from the first end to the second end; and the drift section includes a drift inner surface defining a second slope from the second end to the second electron detector, the second slope being substantially the same as the first slope. ​ The drift section includes a drift inner surface defining a second slope from the second end to the second electron detector, the second slope being substantially the same as the first slope.

14. The charged particle beam system of claim 10, further comprising a beam column, wherein the first electron detector, the second electron detector, and the first scan deflector are located in the beam column.

15. The charged particle beam system of claim 14, wherein: the beam column comprises a booster tube; and the first scan deflector, the first electron detector, and the second electron detector are located in the booster tube or around a length of the booster tube.

16. The charged particle beam system of claim 14, further comprising a sample chamber, the sample chamber comprising a sample holder having a sample bias.

17. The charged particle beam system of claim 10, wherein the first electron detector is a backscattered electron detector configured to measure a first current of backscattered electrons and the second electron detector is a secondary electron detector configured to measure a second current of secondary electrons.

18. A method of using a charged particle beam system, comprising: emitting an electron beam from an electron source through a beam column to a sample holder in a sample chamber, wherein the beam column comprises: a first electron detector; a second electron detector; and a first scan deflector located between the first electron detector and the second electron detector, wherein the first scan deflector comprises a deflector inner surface comprising a truncated conical shape; detecting a first portion of signal electrons emitted from the sample chamber with the first electron detector; detecting a second portion of signal electrons emitted from the sample chamber with the second electron detector; and generating an image based on the first portion of electrons and the second portion of electrons.

19. The method of claim 18, wherein the first electron detector is a backscattered electron detector configured to measure a first current of backscattered electrons and the second electron detector is a secondary electron detector configured to measure a second current of secondary electrons.

20. The method of claim 18, wherein: the beam column comprises a second scan deflector; and the second electron detector is located between the second scan deflector and the first scan deflector.

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