Dynamically decoupled ion pump and charged-particle beam system

Abstract

A connection between an ion pump and a charged-particle beam apparatus includes a flexible conduit connecting the ion pump to the charged-particle beam apparatus. The flexible conduit may have a stiffness of less than 2E4 Newtons per meter. And the flexible conduit may be configured to maintain a vacuum level of less than 1E-6 Torr in the charged-particle beam apparatus.

Description

DYNAMICALLY DECOUPLED ION PUMP AND CHARGED-PARTICLE BEAM SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS[1] This application claims priority of US application 63 / 623,177 which was filed on January 19, 2024 and which is incorporated herein in its entirety by reference.TECHNICAL FIELD[2] The present disclosure generally relates to the field of ion pumps and charged-particle beam systems and, in particular, to dynamically decoupling an ion pump from a charged-particle beam system for improved dynamic performance.BACKGROUND[3] An ion pump is a type of vacuum pump for producing vacuum in a vessel. The ion pump has a cavity. When the cavity is connected to the vessel, gas in the vessel can flow into the cavity. The ion pump can discharge electrons into the cavity that can ionize atoms and molecules of the gas. The ions of the gas can be accelerated by an electric field generated inside the cavity by an anode and a cathode, and eventually strike the cathode. The cathode can be made of chemically active materials and can trap the ions underneath the surface of the materials. Also, some cathode materials can be sputtered by the ions onto a wall of the cavity. The sputtered cathode materials can continue to absorb ions. As a result, gas inside the vessel can be extracted, and the vacuum can be produced in the vessel.[4] Ion pumps are capable of generating very low pressures in a vessel (e.g., as low as IE- 10- mbar). Unlike other types of vacuum pumps, ion pumps have no moving parts and do not use working fluid (e.g., oil). Ion pumps generate less vibration, need little maintenance, and produce little contamination. Because of such advantages, ion pumps are widely used in high-precision apparatuses that use vacuum, such as a scanning electron microscope (SEM).SUMMARY[5] Embodiments consistent with the present disclosure include apparatuses, systems, and methods for reducing resonance for an ion pump. In some embodiments,.[6] In some embodiments, a connection between an ion pump and a charged-particle beam apparatus is disclosed. The connection may include a flexible conduit connecting the ion pump to the charged-particle beam apparatus. The flexible conduit may have a stiffness of less than 2E4 Newtons per meter. And the flexible conduit may be configured to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus.[7] In some embodiments, a system is disclosed. The system may include a charged-particle beam apparatus and an ion pump fluidly coupled to the charged-particle beam apparatus using bellows having a stiffness of less than 2E4 Newtons per meter. The bellows may be able to maintain a vacuumlevel of less than IE-6 Torr in the charged-particle beam apparatus. And a natural frequency of the ion pump may be below 10 Hz. The system may also include a support structure supporting the ion pump.[8] In some embodiments, a method of coupling a charged-particle beam apparatus to an ion pump is disclosed. The method may include connecting the ion pump to the charged-particle beam apparatus using a flexible conduit. The flexible conduit may have a stiffness of less than 2E4 Newtons per meter. And the flexible conduit may be configured to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus.BRIEF DESCRIPTION OF DRAWINGS[9] Figs. 1 A and IB illustrate example systems where a vacuum in a machine is produced by an ion pump, consistent with embodiments of the present disclosure.

[0010] Figs. 2A and 2B illustrate an abstract representation of the systems of Figs. 1 A and IB, respectively, consistent with embodiments of the present disclosure.

[0011] Figs. 3A and 3B illustrate example systems where a machine is fluidly connected to am ion pump using a flexible coupling, consistent with embodiments of the present disclosure.

[0012] Figs. 4A and 4B illustrate an abstract representation of the systems of Figs. 3A and 3B, respectively, consistent with embodiments of the present disclosure.

[0013] Figs. 5A-5C are schematic illustration of equivalent stiffness of a mechanical connection along three different coordinate axes, consistent with embodiments of the present disclosure.

[0014] Fig. 6 illustrates an example ion pump with a flexible conduit, consistent with embodiments of the present disclosure.

[0015] Fig. 7 is a schematic diagram illustrating an example charged-particle beam inspection system, consistent with embodiments of the present disclosure.

[0016] Fig. 8 is a schematic diagram illustrating an example multi-beam beam tool, consistent with embodiments of the present disclosure that can be a part of the example system of Fig. 7.

[0017] Fig. 9 is an exemplary process chart for dynamically decoupling an ion pump from a charged- particle beam apparatus, consistent with embodiments of the current disclosure.DET AIDED DESCRIPTION

[0018] Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of example embodiments do not represent all implementations consistent with the disclosure. Instead, they are merely examples of apparatuses and methods consistent with aspects related to the subject matter recited in the appended claims. For example, although some embodiments are described in the context of utilizing electrons, the disclosure is not so limited. Other types of charged particles (e.g., protons,ions, muons, or any other particle carrying electric charges) may be similarly applied.

[0019] Electronic devices are constructed of circuits formed on a piece of silicon called a substrate. Many circuits may be formed together on the same piece of silicon and are called integrated circuits or ICs. The size of these circuits has decreased dramatically so that many more of them can fit on the substrate. For example, an IC chip in a smartphone can be as small as a thumbnail and yet may include over 2 billion transistors, the size of each transistor being less than 1 / lOOOth the size of a human hair.

[0020] Making these extremely small ICs is a complex, time-consuming, and expensive process, often involving hundreds of individual steps. Errors in even one step have the potential to result in defects in the finished IC, rendering it useless. Thus, one goal of the manufacturing process is to avoid such defects to maximize the number of functional ICs made in the process; that is, to improve the overall yield of the process.

[0021] One component of improving yield is monitoring the chip-making process to ensure that it is producing a sufficient number of functional integrated circuits. One way to monitor the process is to inspect the chip circuit structures at various stages of their formation. Inspection can be carried out using a scanning charged-particle microscope (SCPM), such as a scanning electron microscope (SEM). A SEM can be used to image these extremely small structures, in effect, taking a “picture” of the structures of the wafer. The image can be used to determine if the structure was formed properly in the proper location. If the structure is defective, then the process can be adjusted, so the defect is less likely to recur.

[0022] The working principle of a SEM is similar to a camera. A camera takes a picture by receiving and recording brightness and colors of light reflected or emitted from people or objects. A SEM takes a “picture” by receiving and recording energies or quantities of charged particles (e.g., electrons) reflected or emitted from the structures. Before taking such a “picture,” a charged particle beam may be provided onto the structures, and when the charged particles are reflected or emitted (“exiting”) from the structures, a detector of the SEM may receive and record the energies or quantities of those charged particles to generate an image. To take such a “picture,” some SEMs use a single charged particle beam (referred to as a “single-beam SEM”), while some SEMs use multiple charged particle beams (referred to as a “multi-beam SEM”) to take multiple “pictures” of the wafer. By using multiple charged particle beams, the SEM may provide more charged particle beams onto the structures for obtaining these multiple “pictures,” resulting in more charged particles exiting from the structures. Accordingly, the detector may receive more exiting charged particles simultaneously and generate images of the structures of the wafer with higher efficiency and faster speed.

[0023] Because the charged-particle beams can easily interact with atoms and molecules in the air and cause diffusion of energy and contamination of unwanted particles, the SEM normally needs to work in a vacuum environment. Typically, the SEM has a closed vessel (a “column”) that encloses a charged-particle source that discharges charged particles, a projection system projecting charged-particle beams formed from the discharged charged particles onto a sample stage, the sample stage for holding a sample for inspection, and a charged-particle detection sub-system. For acquiring the vacuum in the column, a vacuum pump may be connected to the column to extract gas. Ion pumps are commonly used for the SEM because of its advantages of generating little vibration, needing little maintenance, and producing little contamination.

[0024] The working principle of an ion pump includes separating (“ionizing”) atoms and molecules of the gas into charged particles (“ions”), driving the ions with a strong electric field into an electrode (a “cathode”) made of absorption materials, and absorbing the ions using the absorption materials. For example, a cavity of the ion pump may be connected to the vessel, where gas may freely flow between the cavity and the vessel. The ion pump can generate a strong electric field in the cavity using an anode and a cathode. The anode may discharge electrons into the cavity. The ion pump may apply a magnetic field (e.g., an axial magnetic field) and an electric field (e.g., a quadrupole electric field) to shape the discharged electrons into a swirling cloud and stabilize it near the anode. The electron cloud has strong electric charges that may ionize surrounding gas atoms and molecules into ions.

[0025] The strong electric field (e.g., typically 3-7 kilovolts) generated by the anode and the cathode may accelerate the ions towards the cathode of the ion pump. The acceleration may cause the ions to impact on the surface of the cathode. The cathode may be made of chemically active materials (e.g., titanium). On impact, some ions may be trapped by the cathode materials underneath its surface, and some ions may sputter some cathode materials onto a wall of the cavity. The sputtered cathode materials may be highly reactive and may continue to absorb the gas in the vessel by a chemical process (“chemisorption”) and a physical process (“physisorption”). The above process may remove the gas and ultimately produce extremely low pressure in the vessel.

[0026] A challenge in existing ion pump designs is that the natural frequency of the ion pump is very low. As a result, the ion pump may easily resonate with low-frequency vibrations in its surrounding environment (e.g., an individual walking nearby, a vehicle passing nearby, a machine operating nearby, or the like). The resonance of the ion pump may propagate the low-frequency vibrations to the vessel (e.g., a column of a SEM) it connects to. Such vibrations may interfere with components (e.g., the column or the stage) of the high-precision SEM. The interference may cause vibration noise in SEM images. The vibration noise may limit the accuracy of data (e.g., critical dimension data) derived from the SEM images, which may limit the inspection resolution of the SEM. Current designs of ion pumps mainly focus on performance metrics (e.g., vacuum pressure, pumping speed, or the like) and seldomly focus on dynamic characteristics (e.g., its natural frequency), which may limit inspection quality of the SEM due to the above reasons.

[0027] Some disclosed embodiments provide apparatuses, systems, and methods that reduce the dynamic coupling between the ion pump and the SEM. In some embodiments, a flexible coupling, such as, for example, bellows may be used to fluidly couple the ion pump to the SEM. The flexible coupling may dynamically decouple the ion pump and the SEM and impede the propagation ofvibration from the ion pump to the machine. By dynamically decoupling the SEM and the ion pump, the impact of the ion pump vibrations on the SEM may be greatly reduced, and consequently, the inspection quality of the SEM can be improved.

[0028] Relative dimensions of components in drawings may be exaggerated for clarity. Within the following description of drawings, the same or like reference numbers refer to the same or like components or entities, and only the differences with respect to the individual embodiments are described.

[0029] As used herein, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, if it is stated that a component may include A or B, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or A and B. As a second example, if it is stated that a component may include A, B, or C, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0030] Figs. 1 A and IB illustrate example systems 100A and 100B where an ion pump is fluidly connected to a machine, such as, for example, an SEM. Systems 100A and 100B may include a machine 102 (e.g., a SEM), an ion pump 104, and a connection (referred to as an “inlet pipe” 108, 108') between them. Inlet pipe 108, 108' is a fluid conduit or a pipe for directing gas extracted from machine 102. In some embodiments, inlet pipe 108, 108' may include a flange connected to a pipe where the flange is fixed (e.g., by bolts, screws, etc.) onto a vessel (e.g., a column) of machine 102 and the pipe is fixed (e.g., by bolting, screwing, pressing, welding, etc.) onto a wall of ion pump 104. When operating, the gas in the vessel of machine 102 may be extracted by ion pump 104 through inlet pipe 108, 108'. Machine 102 may be installed on a chamber 106 that houses the sample being analyzed using a screw connection 110. In some embodiments, as illustrated in Fig. 1A, ion pump 104 may also be connected to the top of chamber 106 by a support arm 112. However, in some embodiments, as illustrated in Fig. IB, support arm 112 may be eliminated and ion pump 104 may be supported solely by inlet pipe 108'.

[0031] Figs 2A and 2B illustrate dynamic representations of systems 100A and 100B, respectively, of Figs. 1 A and IB. In Fig. 2A, the mechanical connection (e.g., inlet pipe 108) between machine 102 and ion pump 104 is represented as a first equivalent spring 208 (having an equivalent stiffness of kzos), and in Fig. 2B the mechanical connection (e.g., inlet pipe 108') between machine 102 and ion pump 104 is represented as a first equivalent spring 208' (having an equivalent stiffness of kzos )■ In Figs. 2A and 2B, the mechanical connection between machine 102 and chamber 106 is represented as a second equivalent spring 210 (having an equivalent stiffness of kzio). And in Fig. 2B, the mechanical connection (e.g., support arm 112) between ion pump 104 and chamber 106 is represented as a third equivalent spring 212 (having an equivalent stiffness of kziz)- In this representation, the actual physical connection between objects is replaced by a theoretical spring, and the behavior of the connection is described using mechanics principles, such as, for example, Hooke's Faw. Hooke's Lawis a fundamental principle in mechanics that describes the relationship between the force applied to an elastic spring and the resulting displacement. For example, when the mechanical connection exhibits linear behavior (e.g., when the deformation of the equivalent spring is proportional to the applied force), Force F=lk-xl, where k is the equivalent stiffness, and x is the displacement. Knowing the force and the corresponding displacement, equivalent stiffness (k) may be obtained from this relationship. The equivalent stiffness of the equivalent spring along different coordinate axes may be similarly obtained by applying a force in different directions (e.g., along the X, Y, and Z axes) and determining the resulting deflection in the different directions. If the mechanical connection exhibits nonlinear behavior, more complex numerical or analytical models (e.g., Finite Element models) can be used to determine the stiffness of the connection along different directions. Representing the mechanical connection between two objects as an equivalent spring (with an equivalent stiffness) is a method of simplifying the analysis while retaining key characteristics of the connection. It allows the use of well-understood principles from mechanics to study and predict the behavior of the connection in various conditions.

[0032] In some embodiments, inlet pipe 108, 108', screw connection 110, and support arm 112 may include multiple components or parts. “Equivalent stiffness” of a multi-part component refers to a simplified representation of the stiffness characteristics of the entire component as a single, equivalent spring. This is done to simplify the analysis of complex structures by replacing them with a simpler model that exhibits similar stiffness behavior. Equivalent stiffness is a measure of how a represented mechanical structure resists deformation when subjected to an external load. For a multi-part component, such as an assembly of interconnected parts or components, each part contributes to the overall stiffness of the structure. The equivalent stiffness is a single stiffness value that represents the combined effect of all the individual stiffness contributions within the multi-part component. It allows a complex structure to be treated as if it were a single, homogeneous entity for analytical purposes. The process of determining the equivalent stiffness of a multi-part component involves considering factors such as the geometry, material properties, and connection methods of the individual parts. In some cases, numerical analysis (e.g., Finite Element analysis) may be used to determine the equivalent stiffness of a multi-part component.

[0033] The stiffness of a mechanical connection between two objects influences the dynamic behavior of the connected objects. Dynamic behavior refers to how the objects respond to dynamic forces, vibrations, or oscillations over time. The stiffness of the connection contributes to the natural frequency of the connected system. Natural frequency is the frequency at which a system vibrates when subjected to an external force and it is influenced by the stiffness of the system. Higher stiffness generally leads to a higher natural frequency, meaning the system will tend to vibrate at higher frequencies. For example, in system 100B of Fig. 2B, the natural frequency / of ion pump 104 may be determined as Eq. (1):where k represents the equivalent stiffness kzos of first equivalent spring 208' (e.g., the stiffness of inlet pipe 108'), and m represents mass of ion pump 104. For existing ion pumps, k may have a small value, and m may have a large value. For example, the natural frequency / may be about 30 Hz when m is 10 kilograms. The surrounding environment of ion pump 104 may include various sources of vibrations, such as, for example, walking individuals, operating machines, electric power, or the like. Such sources of vibrations may cover a spectrum of frequencies, including frequencies of about 30 Hz. For a normal working environment of ion pump 104, existing sources of vibrations may easily cause ion pump 104 to resonate with the low-frequency vibrations of the sources, and the unwanted resonance of ion pump 104 may propagate to machine 102 via the first equivalent spring 208.

[0034] In system 100A of Fig. 2A, typically, the equivalent stiffness kzos of first equivalent spring 208 may be between about 1E5 to 1E6 N / m (or 1 x 105to 1 x 106Newton / meter), the equivalent stiffness kzio of second equivalent spring 210 may be greater than about 1E10 N / m, and the equivalent stiffness kziz of third equivalent spring 212 may be between about 1E5 to 1E7 N / m. And, in some embodiments of system 100 A, the first natural frequency (or the lowest natural frequency) of ion pump 104 may be between about 30-60 Hertz (Hz). In system 100B of Fig. 2B, typically, the equivalent stiffness kzos of first equivalent spring 208' may be above about 1E7 N / m, the equivalent stiffness kzio of second equivalent spring 210 may be greater than about 1E10 N / m, and the first natural frequency of ion pump 104 may be above about 150 Hz.

[0035] When the equivalent stiffness kzos of the first equivalent spring 208 is high (e.g., between about 1E5 to 1E6 N / m), supporting ion pump 104 on chamber 106 using support arm 112 as in system 100A of Fig. 1 A, may negatively impact the serviceability of the system. For example, due to the relatively high stiffness (or increased rigidity) of the connection between ion pump 104 and machine 102, ion pump 104 may need to be realigned with machine 102 every time the machine height is adjusted or support arm 112 is installed or adjusted. Repeatedly realigning ion pump 104 to machine 102 may be time consuming, and consequently, the throughput of system 100A may be negatively affected. The increased equivalent stiffness kzos of first equivalent spring 208' (e.g., above about 1E7 N / m) in system 100B of Fig. 2B may require customization of ion pump 104 (e.g., increased housing thickness, increased coupling thickness, etc.), and therefore, result in an increased cost of ion pump 104. To alleviate these deficiencies, in some embodiments of the current disclosure, a flexible conduit may be used to couple ion pump 104 to machine 102. Since a flexible conduit may flex and better tolerate misalignment between machine 102 and ion pump 104, the need for frequent realignment may be reduced (or eliminated). Moreover, the flexible conduit may enable the use of conventional ionpumps and therefore reduce costs.

[0036] Stiffness of the connection between two objects (e.g., machine 102 and ion pump 104) affects the transmission of vibrations between the connected objects. A stiffer connection (or a connection with high stiffness) facilitates the transmission of vibrations between the objects, while a less stiff (more compliant) connection can isolate or reduce the transmission of vibrations. In other words, when two objects are connected by a connection with low stiffness, vibrations in one object may not be readily transferred to the other object due to the compliant nature of the connection. The low stiffness of the connection allows for greater relative motion and deformation between the objects, which can act as a decoupling mechanism for vibrations. Further, stiffer connections tend to have lower levels of inherent damping, which may result in less energy dissipation during dynamic events. This may lead to longer vibration decay times. In contrast, compliant connections with lower stiffness may provide more damping and can dissipate vibrational energy faster, and thereby, reduce the amplitude of vibrations more quickly.

[0037] Figs. 3A and 3B illustrate exemplary systems 200A and 200B consistent with embodiments of the present disclosure. As in systems 100A and 100B (of Figs. 1A and IB), in systems 200A and 200B, an ion pump 104 is fluidly connected to a machine 102 (such as, for example, an SEM or another charged-particle beam machine). Machine 102 may be installed on chamber 106 using screw connection 110. In system 200A of Fig. 3 A, ion pump 104 is also supported on the top of chamber 106 by support arm 112. In some embodiments, support arm 112 may be eliminated and ion pump 104 may be directly mounted on chamber 106. In system 200B of Fig. 3B, support arm 112 is eliminated. In some such embodiments, ion pump 104 may be supported on the surface of an object (e.g., a bracket, frame, table, ledge, etc.), which is not dynamically connected to system 200B. In both systems 200A and 200B, instead of inlet pipes 108, 108' of systems 100A and 100B (see Figs. 1A and IB), a flexible conduit 308 is used to connect ion pump 104 to machine 102. In systems 300A and 300B, when machine 102 is an SEM, ion pump 104 removes residual gases from the microscope column of machine 102 and maintains the vacuum environment necessary for the proper operation of machine 102. The flexible conduit 308 that connects ion pump 104 to machine 102 serves as a pathway for the evacuated gases to be transported away from machine 102 and expelled from system 200A, 200B.

[0038] Figs 4A and 4B illustrate dynamic representations of systems 200A and 200B, respectively, of Figs. 3A and 3B. Similar to Figs. 2A and 2B, in Figs. 3A and 3B, the mechanical connection between different objects is represented by equivalent springs. In Figs. 4A and 4B, the flexible conduit 308 that connects machine 102 and ion pump 104 is represented by equivalent spring 408 with an equivalent stiffness of k^os- All other mechanical connections (e.g., screw connection 110 between machine 102 and chamber 106 and support arm 112 between ion pump 104 and chamber 106) of systems 200 A and 200B remain the same as in systems 100A and 100B (of Figs. 1A and IB), Therefore, the corresponding equivalent springs and their equivalent stiffnesses remain the same.

[0039] In embodiments of the current disclosure, flexible conduit 308 may have a low stiffness, for example, below 2E4 N / m. In other words, equivalent stiffness s of spring 408 may be less than 2E4 N / m. In some embodiments, as illustrated in Figs. 5A-5C, the equivalent stiffness f k io ) of spring 408 (e.g., the stiffness of flexible conduit 308 of Figs. 4A-4B) along the X, Y and Z axes may be less than 2E4 N / n (though not necessarily the same). Although not required, in some embodiments, the equivalent stiffness for angular rotation may also be less than 2E4 N / n. In some embodiments, s (e.g., along X, Y and Z axes and angular rotation) may be less than 1E4 N / n. When the stiffness of flexible conduit 308 (or the equivalent stiffness of equivalent spring 408) is below 2E4 N / m, the first natural frequency (or the lowest natural frequency) of ion pump 104 may be below 10 Hz. It should be noted that the first natural frequency value (e.g., below 10 Hz) is computed using mass of ion pump 104 and the equivalent stiffness of equivalent spring 408. In some embodiments, the first natural frequency may be below 6 Hz, or about 3 Hz (e.g., between 2 and 4 Hz). As explained previously, when machine 102 and ion pump 104 are connected together by using a mechanical connection with low stiffness (such as flexible conduit 308), vibrations in ion pump 104 may not be readily transferred to machine 102 due to the compliant nature of the connection. Moreover, the mass of ion pump 104 can be removed from machine 102, thereby improving dynamic behavior of the system.

[0040] Any type of flexible conduit 308 having a stiffness less than 2E4 N / m may be used to fluidly couple machine 102 and ion pump 104. Since flexible conduit 308 directs the evacuated gases away from machine 102 to maintain the vacuum environment in machine 102, the type of connection used as flexible conduit 308 may be capable of supporting (or maintaining) a vacuum less than IE-6 Torr. In some embodiments, bellows may be used as flexible conduit 308. Bellows refers to a connection having a structure designed to expand and contract in response to an applied force, allowing for flexibility in movement. In some embodiments, the bellows used as flexible conduit 308 may have an accordion-like structure, with folds or pleats that can expand and contract as needed to accommodate changes in length. In some embodiments, flexible conduit 308 may be (or include) a flexible hose pipe. For example, one or more of a flexible metal hose (e.g., made of stainless steel, another alloy, etc.), a rubber hose (e.g., made of synthetic rubber, elastomers, etc.), a composite hose (e.g., made of layers of materials, such as, for example, rubber or thermoplastic), a polytetrafluoroethylene (PTFE) hose, a thermoplastic hose, a polyvinyl chloride (PVC) hose, etc. In some embodiments, flexible conduit 308 may include an expansion joint (made of a metal or elastomeric materials) that allows relative movement between machine 102 and ion pump 104 and absorbs vibrations.

[0041] In general, flexible conduit 308 is a fluid conduit or a pipe for directing gas extracted from machine 102. In some embodiments, flexible conduit 308 may include a flange connected to a pipe where the flange is fixed (e.g., by bolts, screws, welded, etc.) onto a vessel (e.g., a chamber, column, etc.) of machine 102 and the pipe is fixed (e.g., by bolting, screwing, pressing, welding, etc.) onto a wall of ion pump 104. When operating, the gas in the vessel of machine 102 may be extracted by ion pump 104 through flexible conduit 308. In general, flexible conduit 308 may be connected to ionpump 104 and machine 102 in any known manner. For example, in some embodiments, one end of flexible conduit 308 may be fixedly connected (e.g., welded, etc.) or removably connected (e.g., screwed connection, etc.) to a wall of ion pump 104 and another end of the flexible conduit 308 may be fixedly connected (e.g., welded, etc.) or removably connected (e.g., screwed connection, etc.) to a wall of machine 102. In some embodiments, flexible conduit 308 may include multiple components removably or fixedly connected together. For example, the flexible conduit 308 may include at least one flange portion and a pipe portion. The pipe portion and the flange portion may be removably connected together or may be cast as a single part.

[0042] Fig. 6 illustrates an example of ion pump 104 that may be used in systems 200A and 200B (of Figs. 3A and 3B), consistent with embodiments of the present disclosure. Ion pump 104 may include a pump body (not marked). Pump body may include a cavity inside for gas extraction with wall 120 on its outside. Flexible conduit 308 may be connected to wall 120 of the pump body. In some embodiments, flexible conduit 308 may include a pipe 308A that connects to wall 120, and a flange 308B that connects to pipe 308A. Flange 308B may be connected directly or indirectly (e.g., via another conduit) to machine 102. The structure of flexible conduit 308 illustrated in Fig. 6 is merely exemplary. In general, flexible conduit 308 may have any suitable structure. For example, in some embodiments, flange 308B may be eliminated. In some embodiments, flexible conduit 308 may include a long tube (e.g., similar to pipe 308A) that extends between ion pump 104 and machine 102. In some embodiments, flexible conduit 308 may be configured as bellows. In some embodiments, flexible conduit 308 may include one or more features (e.g., dampers, etc.) that serve to increase the compliance (or decrease the stiffness) of the structure in one or more directions.

[0043] Machine 102 may be any charged-particle beam inspection system (e.g., an SEM), and ion pump 104 may be connected to a vessel of the charged-particle beam inspection system for providing vacuum. Fig. 7 illustrates an example charged-particle beam inspection system 700 consistent with embodiments of the present disclosure. System 700 may be used for imaging. As shown in Fig. 7, system 700 includes a main chamber 701, a load / lock chamber 702, a beam tool 704, and an equipment front end module (EFEM) 706. Beam tool 704 is located within main chamber 701. EFEM 706 includes a first loading port 706a and a second loading port 706b. EFEM 706 may include additional loading port(s). First loading port 706a and second loading port 706b receive wafer front opening unified pods (FOUPs) that contain wafers (e.g., semiconductor wafers or wafers made of other material(s)) or samples to be inspected (wafers and samples may be used interchangeably). A “lot” is a plurality of wafers that may be loaded for processing as a batch.

[0044] One or more robotic arms (not shown) in EFEM 706 may transport the wafers to load / lock chamber 702. Load / lock chamber 702 is connected to a load / lock vacuum pump system (not shown) which removes gas molecules in load / lock chamber 702 to reach a first pressure below the atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) may transport the wafer from load / lock chamber 702 to main chamber 701. Main chamber 701 isconnected to a main chamber vacuum pump system (not shown) which removes gas molecules in main chamber 701 to reach a second pressure below the first pressure. After reaching the second pressure, the wafer is subject to inspection by beam tool 704. Beam tool 704 may be a single-beam system or a multi-beam system.

[0045] A controller 709 is electronically connected to beam tool 704. Controller 709 may be a computer configured to execute various controls of system 700. While controller 709 is shown in Fig. 7 as being outside of the structure that includes main chamber 701, load / lock chamber 702, and EFEM 706, it is appreciated that controller 709 may be a part of the structure. In some embodiments, controller 709 may include one or more processors (not shown). A processor may be a generic or specific electronic device capable of manipulating or processing information. For example, the processor may include any combination of any number of a central processing unit (or “CPU”), a graphics processing unit (or “GPU”), an optical processor, a programmable logic controllers, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a Programmable Logic Array (PLA), a Programmable Array Logic (PAL), a Generic Array Logic (GAL), a Complex Programmable Logic Device (CPLD), a Field-Programmable Gate Array (FPGA), a System On Chip (SoC), an Application-Specific Integrated Circuit (ASIC), and any type circuit capable of data processing. The processor may also be a virtual processor that includes one or more processors distributed across multiple machines or devices coupled via a network.

[0046] In some embodiments, controller 709 may further include one or more memories (not shown). A memory may be a generic or specific electronic device capable of storing codes and data accessible by the processor (e.g., via a bus). For example, the memory may include any combination of any number of a random-access memory (RAM), a read-only memory (ROM), an optical disc, a magnetic disk, a hard drive, a solid-state drive, a flash drive, a security digital (SD) card, a memory stick, a compact flash (CF) card, or any type of storage device. The codes may include an operating system (OS) and one or more application programs (or “apps”) for specific tasks. The memory may also be a virtual memory that includes one or more memories distributed across multiple machines or devices coupled via a network.

[0047] Fig. 8 illustrates a schematic diagram of an example multi-beam beam tool 704 (also referred to herein as machine 102) and an image processing system 890 that may be configured for use in system 700 (Fig. 7), consistent with embodiments of the present disclosure. Beam tool 704 comprises an charged-particle source 802, a gun aperture 804, a condenser lens 806, a primary charged-particle beam 810 emitted from charged-particle source 802, a source conversion unit 812, a plurality of beamlets 814, 816, and 818 of primary charged-particle beam 810, a primary projection optical system 820, a motorized wafer stage 880, a wafer holder 882, multiple secondary charged-particle beams 836, 838, and 840, a secondary optical system 842, and an charged-particle detection device 844. Primary projection optical system 820 can comprise a beam separator 822, a deflection scanning unit 826, and an objective lens 828. Charged-particle detection device 844 can comprise detectionsub-regions 846, 848, and 850.

[0048] Charged-particle source 802, gun aperture 804, condenser lens 806, source conversion unit 812, beam separator 822, deflection scanning unit 826, and objective lens 828 can be aligned with a primary optical axis 860 of apparatus 704. Secondary optical system 842 and charged-particle detection device 844 can be aligned with a secondary optical axis 852 of apparatus 704. Charged- particle source 802 can emit one or more charged particles, such as electrons, protons, ions, muons, or any other particle carrying electric charges. In some embodiments, charged-particle source 802 may be an electron source. For example, charged-particle 802 may include a cathode, an extractor, or an anode, wherein primary electrons can be emitted from the cathode and extracted or accelerated to form primary charged-particle beam 810 (in this case, a primary charged-particle beam) with a crossover (virtual or real) 808. For ease of explanation without causing ambiguity, electrons are used as examples in some of the descriptions herein. However, it should be noted that any charged particle may be used in any embodiment of this disclosure, not limited to electrons. Primary charged-particle beam 810 can be visualized as being emitted from crossover 808. Gun aperture 804 can block off peripheral charged particles of primary charged-particle beam 810 to reduce Coulomb effect. The Coulomb effect may cause an increase in size of probe spots.

[0049] Source conversion unit 812 can comprise an array of image-forming elements and an array of beam-limit apertures. The array of image-forming elements can comprise an array of micro-deflectors or micro-lenses. The array of image-forming elements can form a plurality of parallel images (virtual or real) of crossover 808 with a plurality of beamlets 814, 816, and 818 of primary charged-particle beam 810. The array of beam-limit apertures can limit the plurality of beamlets 814, 816, and 818. While three beamlets 814, 816, and 818 are shown in Fig. 8, embodiments of the present disclosure are not so limited. For example, in some embodiments, the apparatus 704 may be configured to generate a first number of beamlets. In some embodiments, the first number of beamlets may be in a range from 1 to 1000. In some embodiments, the first number of beamlets may be in a range from 200-500. In an example embodiment, an apparatus 704 may generate 400 beamlets.

[0050] Condenser lens 806 can focus primary charged-particle beam 810. The electric currents of beamlets 814, 816, and 818 downstream of source conversion unit 812 can be varied by adjusting the focusing power of condenser lens 806 or by changing the radial sizes of the corresponding beam-limit apertures within the array of beam-limit apertures. Objective lens 828 can focus beamlets 814, 816, and 818 onto a wafer 830 for imaging, and can form a plurality of probe spots 870, 872, and 874 on a surface of wafer 830.

[0051] Beam separator 822 can be a beam separator of Wien filter type generating an electrostatic dipole field and a magnetic dipole field. In some embodiments, if they are applied, the force exerted by the electrostatic dipole field on a charged particle (e.g., an electron) of beamlets 814, 816, and 818 can be substantially equal in magnitude and opposite in a direction to the force exerted on the charged particle by magnetic dipole field. Beamlets 814, 816, and 818 can, therefore, pass straight throughbeam separator 822 with zero deflection angle. However, the total dispersion of beamlets 814, 816, and 818 generated by beam separator 822 can also be non- zero. Beam separator 822 can separate secondary charged-particle beams 836, 838, and 840 from beamlets 814, 816, and 818 and direct secondary charged-particle beams 836, 838, and 840 towards secondary optical system 842.

[0052] Deflection scanning unit 826 can deflect beamlets 814, 816, and 818 to scan probe spots 870, 872, and 874 over a surface area of wafer 830. In response to the incidence of beamlets 814, 816, and 818 at probe spots 870, 872, and 874, secondary charged-particle beams 836, 838, and 840 may be emitted from wafer 830. Secondary charged-particle beams 836, 838, and 840 may comprise charged particles (e.g., electrons) with a distribution of energies. For example, secondary charged-particle beams 836, 838, and 840 may be secondary charged-particle beams including secondary electrons (energies < 50 eV) and backscattered electrons (energies between 50 eV and landing energies of beamlets 814, 816, and 818). Secondary optical system 842 can focus secondary charged-particle beams 836, 838, and 840 onto detection sub-regions 846, 848, and 850 of charged-particle detection device 844. Detection sub-regions 846, 848, and 850 may be configured to detect corresponding secondary charged-particle beams 836, 838, and 840 and generate corresponding signals (e.g., voltage, current, etc.) used to reconstruct an image of surface area of wafer 830.

[0053] The generated signals may represent intensities of secondary charged-particle beams 836, 838, and 840 and may provide the signals to image processing system 890 in communication with charged- particle detection device 844, primary projection optical system 820, and motorized wafer stage 880. The movement speed of motorized wafer stage 880 may be adjusted to adjust the time intervals between consecutive beam scans of an area on wafer 830. The time intervals may need to be adjusted due to different materials on wafer 830 having different resistance-capacitance characteristics, thereby exhibiting varying sensitivity to imaging timing.

[0054] The intensity of secondary charged-particle beams 836, 838, and 840 may vary in accordance with the external or internal structure of wafer 830, and thus may indicate whether wafer 830 includes defects. Moreover, as discussed above, beamlets 814, 816, and 818 may be projected onto different locations of the top surface of wafer 830, or different sides of wafer 830 at a particular location, to generate secondary charged-particle beams 836, 838, and 840 of different intensities. Therefore, by mapping the intensity of secondary charged-particle beams 836, 838, and 840 with the areas of wafer 830, image processing system 890 may reconstruct an image that reflects the characteristics of internal or external structures of wafer 830.

[0055] In some embodiments, image processing system 890 may include an image acquirer 892, a storage 894, and a controller 896. Image acquirer 892 may comprise one or more processors. For example, image acquirer 892 may comprise a computer, server, mainframe host, terminals, personal computer, any kind of mobile computing devices, and the like, or a combination thereof. Image acquirer 892 may be communicatively coupled to charged-particle detection device 844 of beam tool 704 through a medium such as an electric conductor, optical fiber cable, portable storage media, IR,Bluetooth, internet, wireless network, wireless radio, or a combination thereof. In some embodiments, image acquirer 892 may receive a signal from charged-particle detection device 844 and may construct an image. Image acquirer 892 may thus acquire images of wafer 830. Image acquirer 892 may also perform various post-processing functions, such as generating contours, superimposing indicators on an acquired image, and the like. Image acquirer 892 may be configured to perform adjustments of brightness and contrast of acquired images. In some embodiments, storage 894 may be a storage medium such as a hard disk, flash drive, cloud storage, random access memory (RAM), other types of computer-readable memory, and the like. Storage 894 may be coupled with image acquirer 892 and may be used for saving scanned raw image data as original images, and postprocessed images. Image acquirer 892 and storage 894 may be connected to controller 896. In some embodiments, image acquirer 892, storage 894, and controller 896 may be integrated together as one control unit.

[0056] In some embodiments, image acquirer 892 may acquire one or more images of a wafer based on an imaging signal received from charged-particle detection device 844. An imaging signal may correspond to a scanning operation for conducting charged particle imaging. An acquired image may be a single image including a plurality of imaging areas. The single image may be stored in storage 894. The single image may be an original image that may be divided into a plurality of regions. Each of the regions may comprise one imaging area containing a feature of wafer 830. The acquired images may comprise multiple images of a single imaging area of wafer 830 sampled multiple times over a time sequence. The multiple images may be stored in storage 894. In some embodiments, image processing system 890 may be configured to perform image processing steps with the multiple images of the same location of wafer 830.

[0057] In some embodiments, image processing system 890 may include measurement circuitries (e.g., analog-to-digital converters) to obtain a distribution of the detected secondary charged particles (e.g., secondary electrons). The charged-particle distribution data collected during a detection time window, in combination with corresponding scan path data of beamlets 814, 816, and 818 incident on the wafer surface, can be used to reconstruct images of the wafer structures under inspection. The reconstructed images can be used to reveal various features of the internal or external structures of wafer 830, and thereby can be used to reveal any defects that may exist in the wafer.

[0058] In some embodiments, the charged particles may be electrons. When electrons of primary charged-particle beam 810 are projected onto a surface of wafer 830 (e.g., probe spots 870, 872, and 874), the electrons of primary charged-particle beam 810 may penetrate the surface of wafer 830 for a certain depth, interacting with particles of wafer 830. Some electrons of primary charged-particle beam 810 may elastically interact with (e.g., in the form of elastic scattering or collision) the particles of wafer 830 and may be reflected or recoiled out of the surface of wafer 830. An elastic interaction conserves the total kinetic energies of the bodies (e.g., electrons of primary charged-particle beam 810 and particles of wafer 830) of the interaction, in which the kinetic energy of the interacting bodiesdoes not convert to other forms of energy (e.g., heat, electromagnetic energy, etc.). Such reflected electrons generated from elastic interaction may be referred to as backscattered electrons (BSEs). Some electrons of primary charged-particle beam 810 may inelastically interact with (e.g., in the form of inelastic scattering or collision) the particles of wafer 830. An inelastic interaction does not conserve the total kinetic energies of the bodies of the interaction, in which some or all of the kinetic energy of the interacting bodies convert to other forms of energy. For example, through the inelastic interaction, the kinetic energy of some electrons of primary charged-particle beam 810 may cause electron excitation and transition of atoms of the particles. Such inelastic interaction may also generate electrons exiting the surface of wafer 830, which may be referred to as secondary electrons (SEs). Yield or emission rates of BSEs and SEs depend on, e.g., the material under inspection and the landing energy of the electrons of primary charged-particle beam 810 landing on the surface of the material, among others. The energy of the electrons of primary charged-particle beam 810 may be imparted in part by its acceleration voltage (e.g., the acceleration voltage between the anode and cathode of charged-particle source 802 in Fig. 8). The quantity of BSEs and SEs may be more or fewer (or even the same) than the injected electrons of primary charged-particle beam 810.

[0059] The images generated by SEM may be used for defect inspection. For example, a generated image capturing a test device region of a wafer may be compared with a reference image capturing the same test device region. The reference image may be predetermined (e.g., by simulation) and include no known defect. If a difference between the generated image and the reference image exceeds a tolerance level, a potential defect may be identified. As another example, the SEM may scan multiple regions of the wafer, each region including a test device region designed as the same, and generate multiple images capturing those test device regions as manufactured. The multiple images may be compared with each other. If a difference between the multiple images exceeds a tolerance level, a potential defect may be identified.

[0060] In some embodiments, machine 102 (of Figs. 1A-5C) may be beam tool 704, and many components of beam tool 704 may work in a vacuum environment. For example, a vessel (e.g., a column) of beam tool 704 may enclose at least one of charged-particle source 802, gun aperture 804, condenser lens 806, source conversion unit 812, primary projection optical system 820, beam separator 822, deflection scanning unit 826, objective lens 828, wafer 830, wafer holder 882, motorized wafer stage 880, secondary optical system 842, or charged-particle detection device 844. Ion pump 104 may be connected to the vessel of beam tool 704 and extract the gas therein for providing the vacuum. As previously described, by incorporating a flexible conduit 308 to fluidly couple beam tool 704 to ion pump 104 the likelihood of vibrations (or other movement) of the ion pump being transferred to beam tool 704 may be greatly reduced, and the inspection quality of beam tool 704 may be improved. It should be noted that although a multi-beam instrument is illustrated in Fig. 8, the current disclosure is equally applicable to a single beam instrument. In other words, the above-described flexible conduit may also be used to fluidly couple a single beam tool to an ion pump104 to reduce the transmission of vibrations, etc. from the ion pump to the beam, and thereby improve the inspection quality of the beam tool.

[0061] Reference is now made to Fig. 9, which illustrates a process flowchart representing an exemplary method 900 for dynamically decoupling an ion pump from a changed-particle beam apparatus (e.g., machine 102, beam tool 704, etc.). In step 910, a charged-particle beam apparatus may be selected. In step 920, an ion pump may be selected. And in step 930, the charged-particle beam apparatus and the ion pump may be fluidly connected using a flexible conduit such that the conduit serves as a pathway for gases to be evacuated and transported away from the charged-particle beam apparatus. The flexible conduit may be configured to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus. The flexible conduit may have an equivalent stiffness of less than 2E4 N / m, or less that 1E4 N / m in some embodiments. When connected using the flexible conduit, the lowest natural frequency of the ion pump may be below 10 Hz, or less than 6 Hz in some embodiments. In some embodiments, the natural frequency may be about 3 Hz. The flexible conduit may be connected to the charged-particle beam apparatus and the ion pump in any manner. Since the charged-particle beam apparatus and the ion pump are connected together by a flexible conduit with low equivalent stiffness, vibrations in the ion pump may not be readily transferred to the charged- particle beam apparatus due to the compliant nature of the connection. In other words, the low stiffness of the flexible conduit may allow for greater relative motion and deformation between the ion pump and the charged-particle beam apparatus, thereby dynamically decoupling the two devices.

[0062] The embodiments my further be described using the following clauses:1. A connection between an ion pump and a charged-particle beam apparatus, comprising: a flexible conduit connecting the ion pump to the charged-particle beam apparatus, wherein the flexible conduit has a stiffness of less than 2E4 Newtons per meter, and wherein the flexible conduit is configured to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus.2. The connection of clause 1, wherein a natural frequency of the ion pump is below 10 Hz.3. The connection of any of clauses 1-2, wherein the flexible conduit is connected to a chamber of the charged-particle beam, and wherein the ion pump is configured to generate a vacuum in the chamber.4. The connection of any of clauses 1-2, wherein the stiffness of the flexible conduit is less than 1E4 Newtons per meter.5. The connection of clause 1, wherein a natural frequency of the ion pump is below 6 Hz.6. The connection of clause 1, wherein a natural frequency of the ion pump is about 3 Hz.7. The connection of any of clauses 1-2, wherein the flexible conduit comprises bellows.8. The connection of any of clauses 1-2, wherein the flexible conduit comprises a flexible hose pipe.9. The connection of clause 1, further comprising a sample chamber, wherein the charged-particlebeam apparatus is connected to the sample chamber.10. The connection of clause 9, wherein the ion pump is connected to the sample chamber.11. The connection of clause 1, wherein the ion pump is supported by an object that is not dynamically connected to the charged-particle beam apparatus.12. The connection of any of clauses 1, 2, 5, 6, and 9-11, wherein one end of the flexible conduit is welded to a wall of the ion pump.13. The connection of any of clauses 1, 2, 5, 6, and 9-11, wherein the flexible conduit includes multiple components.14. The connection of clause 13, wherein the multiple components comprises a pipe portion and a flange portion.15. The connection of clause 14, wherein the pipe portion is removably connected to the flange portion.16. The connection of clause 14, wherein the flange portion and the pipe portion are cast as a single part.17. A system comprising: a charged-particle beam apparatus; an ion pump fluidly coupled to the charged-particle beam apparatus using bellows having a stiffness of less than 2E4 Newtons per meter, wherein the bellows is able to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus, and wherein a natural frequency of the ion pump is below 10 Hz; and a support structure supporting the ion pump.18. The system of clause 17, wherein a natural frequency of the ion pump is below 6 Hz.19. The system of clause 17, wherein the natural frequency of the ion pump is about 3 Hz.20. The system of any of clauses 17-19, wherein the stiffness of the bellows is less than 1E4 Newtons per meter.21. The system of any of clauses 17-19, further comprising a sample chamber, wherein the charged-particle beam apparatus is connected to the sample chamber.22. The system of clause 21, wherein the support structure is connected to the sample chamber.23. The system of any of clauses 17-19, wherein the support structure is not dynamically connected to the charged-particle beam apparatus.24. The system of any of clauses 17-19, wherein the bellows includes multiple components.25. The system of clause 24, wherein the multiple components comprises a pipe portion and a flange portion.26. The system of clause 25, wherein the pipe portion is removably connected to the flange portion.27. The system of clause 25, wherein the flange portion and the pipe portion are cast as a single part.28. A method of coupling a charged-particle beam apparatus to an ion pump, the method comprising: connecting the ion pump to the charged-particle beam apparatus using a flexible conduit, wherein the flexible conduit has a stiffness of less than 2E4 Newtons per meter, and wherein the flexible conduit is configured to maintain a vacuum level of less than IE-6 Torr in the charged- particle beam apparatus.29. The method of clause 28, wherein a natural frequency of the ion pump is below 10 Hz.30. The method of any of clauses 28-29, wherein the flexible conduit is connected to a chamber of the charged-particle beam, and wherein the ion pump is configured to generate a vacuum in the chamber.31. The method of any of clauses 28-29, wherein the stiffness of the flexible conduit is less than 1E4 Newtons per meter.32. The method of clause 28, wherein a natural frequency of the ion pump is below 6 Hz.33. The method of clause 28, wherein a natural frequency of the ion pump is about 3 Hz.34. The method of any of clauses 28-29 and 32-33, wherein the flexible conduit comprises bellows.35. The method of any of clauses 28-29 and 32-33, wherein the flexible conduit comprises a flexible hose pipe.

[0063] It will be appreciated that the embodiments of the present disclosure are not limited to the exact construction that has been described above and illustrated in the accompanying drawings and that various modifications and changes may be made without departing from the scope thereof. The present disclosure has been described in connection with various embodiments, other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as examples only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

CLAIMS1. A connection between an ion pump and a charged-particle beam apparatus, comprising: a flexible conduit connecting the ion pump to the charged-particle beam apparatus, wherein the flexible conduit has a stiffness of less than 2E4 Newtons per meter, and wherein the flexible conduit is configured to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus.

2. The connection of claim 1, wherein a natural frequency of the ion pump is below 10 Hz.

3. The connection of claim 1, wherein the flexible conduit is connected to a chamber of the charged- particle beam, and wherein the ion pump is configured to generate a vacuum in the chamber.

4. The connection of claim 1, wherein the stiffness of the flexible conduit is less than 1E4 Newtons per meter.

5. The connection of claim 1, wherein a natural frequency of the ion pump is below 6 Hz.

6. The connection of claim 1, wherein a natural frequency of the ion pump is about 3 Hz.

7. The connection of claim 1, wherein the flexible conduit comprises bellows.

8. The connection of claim 1, wherein the flexible conduit comprises a flexible hose pipe.

9. The connection of claim 1, further comprising a sample chamber, wherein the charged-particle beam apparatus is connected to the sample chamber.

10. The connection of claim 9, wherein the ion pump is connected to the sample chamber.

11. The connection of claim 1, wherein the ion pump is supported by an object that is not dynamically connected to the charged-particle beam apparatus.

12. The connection of claim 1, wherein one end of the flexible conduit is welded to a wall of the ion pump.

13. The connection of claim 1, wherein the flexible conduit includes multiple components.

14. The connection of claim 13, wherein the multiple components comprises a pipe portion and a flange portion.

15. A system comprising: a charged-particle beam apparatus; an ion pump fluidly coupled to the charged-particle beam apparatus using bellows having a stiffness of less than 2E4 Newtons per meter, wherein the bellows is able to maintain a vacuum level of less than IE-6 Torr in the charged-particle beam apparatus, and wherein a natural frequency of the ion pump is below 10 Hz; and a support structure supporting the ion pump.

Images