Fluid transport system for charged particle systems

Abstract

To provide apparatuses, systems and methods for transferring fluid to a stage in a charged particle beam system.SOLUTION: In some embodiments, a stage may be configured to secure a wafer; a chamber may be configured to house the stage; and a tube may be provided within the chamber to transfer fluid between the stage and an outside of the chamber. The tube may include a first tubular layer of a first material, which is a flexible polymer; and a second tubular layer of a second material, which is configured to reduce permeation of fluid or gas through the tube. In some embodiments, a system may include a degasser system outside of the chamber, where the degasser system may be configured to remove gas from the transfer fluid before the transfer fluid enters the tube.SELECTED DRAWING: Figure 3C

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 62 / 978,188, filed February 18, 2020, and U.S. Application No. 62 / 989,464, filed March 13, 2020, each of which is incorporated by reference in its entirety into this specification.

[0002] FIELD OF THE DISCLOSURE

[0002] The description herein relates to the field of charged particle beam systems, and more specifically to a system for transporting fluid in a charged particle beam inspection system. [Background technology]

[0003]

[0003] In the manufacturing process of integrated circuits (ICs), unfinished or finished circuit components are inspected to ensure that they are manufactured according to the design and are free of defects. Inspection systems that use optical microscopes typically have a resolution of up to a few hundred nanometers, with the resolution being limited by the wavelength of light. As the physical size of IC components continues to shrink to sub-100 nanometers or even sub-10 nanometers, inspection systems with higher resolution than those that use optical microscopes are needed.

[0004]

[0004] Charged particle (e.g., electron) beam microscopes with resolution down to less than 1 nanometer, such as scanning electron microscopes (SEMs) or transmission electron microscopes (TEMs), serve as practical tools for inspecting IC components with sub-100 nanometer feature sizes. When using an SEM, electrons from a single primary electron beam, or multiple primary electron beams, may be focused on a wafer at a location of interest during inspection. The primary electrons interact with the wafer and may be backscattered or may cause the wafer to emit secondary electrons. The intensity of the electron beam, including the backscattered and secondary electrons, may vary based on the characteristics of the wafer's internal and external structure, which may indicate whether the wafer is defective. Summary of the Invention

[0005]

[0005] Embodiments of the present disclosure provide an apparatus, system, and method for transferring water to a stage in a charged particle beam system. In some embodiments, the stage may be configured to secure a wafer, a chamber may be configured to house the stage, and a tube may be provided within the chamber for transferring a fluid between the stage and an exterior of the chamber, the tube comprising a first tubular layer of a first material that is a flexible polymer and a second tubular layer of a second material configured to reduce tube permeation of fluid or gas.

[0006]

[0006] In some embodiments, a tube may be provided within the vacuum chamber and configured to transfer a fluid between the stage and outside the vacuum chamber, and the tube may include a first tubular layer of a first material, which is a flexible polymer, and a second tubular layer of a second material configured to reduce fluid or gas permeation through the tube.

[0007] In some embodiments, a method is provided for forming a tube in a vacuum chamber for transferring a fluid between a stage and an exterior of the vacuum chamber, the method may include forming a first tubular layer of a first material that is a flexible polymer, forming a second tubular layer of a second material configured to reduce tube permeation over the first tubular layer, the second material configured to reduce tube permeation of a fluid or gas, and applying a negative bias to the tube via a conductive structure during plasma deposition of the second tubular layer.

[0008] In some embodiments, a system may include a stage configured to secure a wafer, a chamber configured to house the stage, the chamber configured to operate in a vacuum environment, a first tube disposed within the chamber and configured to transfer a fluid between the stage and an exterior of the chamber, and a degassing system disposed exterior to the chamber. The degassing system may include a housing including a plurality of second tubes and configured to receive the transfer fluid, and a vacuum system configured to remove gas from the transfer fluid before the transfer fluid enters the first tube. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system consistent with an embodiment of the present disclosure. [Diagram 2]

[0010] 2 is a schematic diagram illustrating an example multi-beam system that is part of the example charged particle beam inspection system of FIG. 1 consistent with an embodiment of the present disclosure. [Figure 3A]

[0011] FIG. 3 is a schematic diagram illustrating an example fluid transfer system that is part of the example multi-beam system of FIG. 2 consistent with an embodiment of the present disclosure. [Figure 3B]

[0012] FIG. 3 is a schematic diagram illustrating an example fluid transfer system that is part of the example multi-beam system of FIG. 2 consistent with an embodiment of the present disclosure. [Figure 3C]

[0013] FIG. 3C is a schematic diagram illustrating an example degassing system that is part of the example fluid transfer system of FIG. 3B consistent with embodiments of the present disclosure. [Figure 3D]

[0014] FIG. 2 is a diagram of a hollow fiber membrane tube consistent with an embodiment of the present disclosure. [Figure 4A]

[0015] 4 is a graph illustrating an example relationship between time and pressure in a vacuum chamber. [Figure 4B]

[0016] 4 is a graph illustrating an example relationship between time and pressure in a vacuum chamber. [Diagram 5]

[0017] This is a transparent diagram. [Figure 6]

[0018] FIG. 1 is a diagram of a multi-layer fluid transfer tube consistent with an embodiment of the present disclosure. [Figure 7]

[0019] FIG. 1 is a transmission diagram consistent with embodiments of the present disclosure. [Figure 8]

[0020] 4 is a graph illustrating an example relationship between time and pressure in a vacuum chamber. [Figure 9]

[0021] 1 is a flow chart of an exemplary process for forming a fluid transfer tube consistent with embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010]

[0022] Reference will now be made in detail to the exemplary embodiments. Examples of these embodiments 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 noted. The implementations described in the following description of the exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, they are merely examples of apparatus and methods consistent with aspects related to the subject matter described in the appended claims. For example, although some embodiments are described in the context of utilizing an electron beam, the present disclosure is not so limited. Other types of charged particle beams may be applied as well. Additionally, other imaging systems may be used, such as optical imaging, photodetection, x-ray detection, and the like.

[0011]

[0023] Electronic devices consist 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 an integrated circuit, or IC. The size of these circuits is decreasing dramatically so that many more circuits can fit on the substrate. For example, an IC chip in a smartphone may be as small as a thumbnail, yet contain over 2 billion transistors, each smaller than 1 / 1000th the size of a human hair.

[0012]

[0024] Manufacturing these extremely small ICs is a complex, time-consuming, and expensive process, often involving hundreds of individual steps. An error in just one step can result in a defect in the finished IC, rendering it useless. Thus, one goal of the manufacturing process is to avoid such defects and maximize the number of functional ICs produced in the process, i.e., to improve the overall yield of the process.

[0013]

[0025] One element of improving yield is monitoring the chip fabrication process to ensure that a sufficient number of functional integrated circuits are being produced. One way to monitor the process is to inspect the chip circuit structures at various stages in their formation. Inspection is sometimes performed using a scanning electron microscope (SEM). An SEM allows one to image these very small structures, essentially taking a "picture" of the structures on the wafer. This image can be used to determine if the structures were formed properly, and if they were formed in the correct location. If the structures are defective, the process can be adjusted to make it less likely that the defects will occur again.

[0014]

[0026] The working principle of an SEM is similar to that of a camera. A camera takes a picture by receiving and recording the brightness and color of light reflected or emitted from a person or object. An SEM takes a "picture" by receiving and recording the energy or quantity of electrons reflected or emitted from a structure. Before taking such a "picture," an electron beam may be provided on the structure, and as the electrons reflect or emit ("emit") from the structure, a detector in the SEM may receive and record the energy or quantity of those electrons to produce an image. Some SEMs use a single electron beam to take such a "picture" (called "single-beam SEMs"), while other SEMs use multiple electron beams to take multiple "pictures" of the wafer (called "multi-beam SEMs"). By using multiple electron beams, the SEM may provide more electron beams on the structure to obtain these multiple "pictures," resulting in more electrons being emitted from the structure. Thus, the detector may receive more emitted electrons simultaneously, producing images of the structures on the wafer with greater efficiency and greater speed.

[0015]

[0027] Inspection involves moving a stage that holds the wafer in a vacuum chamber. However, the motors used to move the stage often dissipate large amounts of heat. Prolonged exposure of the wafer to excessive heat can cause the wafer, along with structures on the wafer, to expand, resulting in the wafer expanding away from its target location. Such thermal drift of the wafer can cause fatal errors in manufacturing computer chips or identifying defects on the wafer. Even small temperature changes can cause the area of ​​interest to quickly move out of the field of view of the SEM image, making it difficult to obtain images and analytical data from that area, adversely affecting throughput and inspection yield. Additionally, thermal exposure of nearby photoelectric components such as position sensors, mirrors, and motors can cause stage positioning errors and beam placement accuracy errors.

[0016]

[0028] SEMs may operate in a vacuum chamber environment. However, when an SEM is equipped with or operates in a vacuum environment, water vapor or air molecules may leak into the vacuum chamber from other system components, which may be undesirable for several reasons. One is that leakage may slow throughput or prevent the vacuum chamber from reaching a predetermined pressure by taking longer for the vacuum chamber to reach a predetermined pressure before inspection of the wafer can occur. For example, in a vacuum environment, water vapor or air molecules may leak into the vacuum chamber from fluid transfer tubes used to cool the stage. When water vapor or air molecules leak into the vacuum chamber, the pressure in the vacuum chamber increases, thereby preventing the vacuum chamber from reaching a predetermined pressure required for inspection. This long time for the system to reach a predetermined pressure (e.g., pump-down time) may reduce system availability.

[0017]

[0029] Additionally, water vapor and air molecules can reduce the lifetime of the inspection system due to components in the system that are sensitive to such contaminants (e.g., pure aluminum components, high voltage components, charged particle source components, etc.). Thus, the ability to prevent water vapor and air molecules from entering the vacuum chamber is essential to improve the throughput and lifetime of the inspection system. The choice of material for the fluid transfer tubes can be essential to retain the fluid and gas. The fluid transfer tubes should also be flexible to accommodate the moving stage while preventing water vapor or gas molecules from escaping into the vacuum chamber. In some embodiments, the use of a degassing system can remove dissolved gas from the fluid before it enters one or more tubes in the vacuum chamber to minimize gas leaking into the vacuum chamber.

[0018]

[0030] This disclosure describes, among other things, methods and systems for providing flexible fluid transfer tubes for cooling a wafer stage while retaining transferred fluids and gases. This disclosure also describes, among other things, methods and systems for providing a degassing system outside the vacuum chamber for removing gases from the fluid before the fluid enters one or more tubes in the vacuum chamber. In some embodiments, the degassing system may be provided inside the vacuum chamber. In some embodiments, an inspection system may include a stage configured to secure a wafer, a vacuum chamber containing the stage, and a number of tubes inside the chamber for transferring water and other fluids and gases between the stage and outside the chamber to a fluid cabinet or other components inside or outside the system. In some embodiments, each tube may include a flexible polymer base that is coated with an inorganic or metallic material. The retention of the transfer fluid may be increased by applying a negative bias to the flexible polymer base during plasma deposition to accelerate the coating ions so that they may penetrate the top layer of the flexible polymer base. In some embodiments, each tube may include a combination of hydrophobic or hydrophilic materials that may retain water vapor and gases in the fluid. In some embodiments, a multi-beam inspection system may be used. In some embodiments, a degassing system may be provided outside the vacuum chamber. The degassing system may include a vacuum pump system configured to remove gas from the fluid before the fluid enters one or more tubes in the vacuum chamber. The degassing system may be used with a single wall tube in the vacuum chamber or a multi-layer tube in the vacuum chamber, as described above. The inspection system may accommodate multiple applications that optimize throughput of the inspection system.

[0019]

[0031] In the drawings, the relative dimensions of components may be exaggerated for clarity. In the following description of the drawings, the same or similar reference numbers refer to the same or similar components or entities and only differences with respect to individual embodiments are described.

[0020]

[0032] As used herein, unless specifically stated otherwise, the term "or" includes all possible combinations unless impracticable. For example, if it is stated that a component may include A or B, the component may include A or B, or A and B, unless specifically stated otherwise or impracticable. As a second example, if it is stated that a component may include A, B, or C, the component may include A, B, or C, or A and B, A and C, or B and C, or A, B, and C, unless specifically stated otherwise or impracticable.

[0021]

[0033] FIG. 1 illustrates an exemplary electron beam inspection (EBI) system 100 consistent with embodiments of the present disclosure. The EBI system 100 can be used for imaging. As shown in FIG. 1, the EBI system 100 includes a main chamber 101, a load / lock chamber 102, an electron beam tool 104, and an equipment front-end module (EFEM) 106. The electron beam tool 104 is located within the main chamber 101. The EFEM 106 includes a first loading port 106a and a second loading port 106b. The EFEM 106 may include additional loading ports. The first loading port 106a and the second loading port 106b receive a wafer front-opening integrated pod (FOUP) containing a wafer (e.g., a semiconductor wafer or a wafer made of other material(s)) or a sample to be inspected (wafer and sample may be used interchangeably). A "lot" is a number of wafers that can be loaded for batch processing.

[0022]

[0034] One or more robot arms (not shown) of the EFEM 106 may transport the wafer to the load / lock chamber 102. The load / lock chamber 102 is connected to a load / lock vacuum pumping system (not shown) that removes gas molecules in the load / lock chamber 102 to reach a first pressure below atmospheric pressure. After the first pressure is reached, the one or more robot arms (not shown) may transport the wafer from the load / lock chamber 102 to the main chamber 101. The main chamber 101 is connected to a main chamber vacuum pumping system (not shown) that removes gas molecules in the main chamber 101 to reach a second pressure below the first pressure. After the second pressure is reached, the wafer is subjected to inspection by the electron beam tool 104. The electron beam tool 104 may be a single beam system or a multi-beam system.

[0023]

[0035] A controller 109 is electronically connected to the electron beam tool 104. The controller 109 may be a computer configured to perform various controls of the EBI system 100. Although the controller 109 is shown in Figure 1 as being external to the structure that includes the main chamber 101, the load / lock chamber 102, and the EFEM 106, it will be understood that the controller 109 may be part of such a structure.

[0024]

[0036] In some embodiments, the controller 109 may include one or more processors (not shown). A processor may be a general-purpose or specific electronic device capable of manipulating or processing information. For example, a processor may include any combination of a central processing unit (i.e., "CPU"), a graphics processing unit (i.e., "GPU"), an optical processor, a programmable logic controller, a microcontroller, a microprocessor, a digital signal processor, an intellectual property (IP) core, a programmable logic array (PLA), a programmable array logic (PAL), a general purpose array logic (GAL), a complex programmable logic device (CPLD), a field programmable gate array (FPGA), a system on a chip (SoC), an application specific integrated circuit (ASIC), and any type of circuit having data processing capabilities. A processor may also be a virtual processor, including one or more processors distributed across multiple machines or devices coupled via a network.

[0025]

[0037] In some embodiments, the controller 109 may further comprise one or more memories (not shown). A memory may be a general-purpose or specific electronic device capable of storing code and data accessible by a processor (e.g., via a bus). For example, the memory may include any combination of random access memory (RAM), read-only memory (ROM), optical disks, magnetic disks, hard drives, solid-state drives, flash drives, security digital (SD) cards, memory sticks, compact flash (CF) cards, or any type of storage device. The code may include an operating system (OS) and one or more application programs (i.e., "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 over a network.

[0026]

[0038] Reference is now made to FIG. 2, which is a schematic diagram illustrating an exemplary electron beam tool 104 including a multi-beam inspection tool that is part of the EBI system 100 of FIG. 1, consistent with an embodiment of the present disclosure. In some embodiments, the electron beam tool 104 may operate as a single beam inspection tool that is part of the EBI system 100 of FIG. 1. The multi-beam electron beam tool 104 (also referred to herein as the apparatus 104) comprises an electron source 201, a Coulomb aperture plate (or "gun aperture plate") 271, a collection lens 210, a source conversion unit 220, a primary projection system 230, a motorized stage 209, and a sample holder 207 supported by the motorized stage 209 for holding a sample 208 (e.g., a wafer or photomask) to be inspected. The multi-beam electron beam tool 104 may further comprise a secondary projection system 250 and an electron detection device 240. The primary projection system 230 may comprise an objective lens 231. The electronic detection device 240 may comprise a number of detection elements 241, 242, and 243. The beam separator 233 and the deflection scanning unit 232 may be located within the primary projection system 230.

[0027]

[0039] The electron source 201, the Coulomb aperture plate 271, the collector lens 210, the radiation source conversion unit 220, the beam separator 233, the deflection scanning unit 232, and the primary projection system 230 may be aligned with a primary optical axis 204 of the apparatus 104. The secondary projection system 250 and the electron detection device 240 may be aligned with a secondary optical axis 251 of the apparatus 104.

[0028]

[0040] The electron source 201 may comprise a cathode (not shown) and an extractor or anode (not shown), and in operation the electron source 201 is configured to emit primary electrons from the cathode, which are extracted or accelerated by the extractor and / or anode to form a primary electron beam 202, which forms a (virtual or real) primary beam crossover 203. The primary electron beam 202 may be visualized as emitting from the primary beam crossover 203.

[0029]

[0041] The source conversion unit 220 may comprise an image forming element array (not shown), an aberration compensator array (not shown), a beam limiting aperture array (not shown), and a pre-bending micro deflector array (not shown). In some embodiments, the pre-bending micro deflector array deflects the multiple primary beamlets 211, 212, 213 of the primary electron beam 202 to be perpendicularly incident on the beam limiting aperture array, the image forming element array, and the aberration compensator array. In some embodiments, the apparatus 104 may operate as a single beam system in which a single primary beamlet is generated. In some embodiments, the condenser lens 210 is designed to focus the primary electron beam 202 into a parallel beam that is perpendicularly incident on the source conversion unit 220. The imaging element array may comprise a plurality of micro deflectors or micro lenses to affect the plurality of primary beamlets 211, 212, 213 of the primary electron beam 202 and form a plurality of (virtual or real) parallel images of the primary beam crossover 203, one for each of the primary beamlets 211, 212, and 213. In some embodiments, the aberration compensator array may include a field curvature compensator array (not shown) and an astigmatism compensator array (not shown). The field curvature compensator array may comprise a plurality of micro lenses to compensate for the field curvature aberration of the primary beamlets 211, 212, and 213. The astigmatism compensator array may comprise a plurality of micro astigmatism correctors to compensate for the astigmatism of the primary beamlets 211, 212, and 213. The beam limiting aperture array may be configured to limit the diameter of each of the primary beamlets 211, 212, and 213. 2 shows three primary beamlets 211, 212, and 213 as an example, it will be understood that the source conversion unit 220 may be configured to form any number of primary beamlets. The controller 109 may be connected to various parts of the EBI system 100 of FIG. 1, such as the source conversion unit 220, the electronic detection device 240, the primary projection system 230, or the motorized stage 209.In some embodiments, the controller 109 may perform various image and signal processing functions, as described in more detail below. The controller 109 may also generate various control signals to control the operation of the charged particle beam inspection system.

[0030]

[0042] The condenser lens 210 is configured to focus the primary electron beam 202. The condenser lens 210 may be further configured to adjust the current of the primary beamlets 211, 212, and 213 downstream of the source conversion unit 220 by varying the focusing power of the condenser lens 210. Alternatively, the current may be varied by changing the radial size of the beam-limiting aperture in the beam-limiting aperture array corresponding to the individual primary beamlets. The current may be varied by changing both the radial size of the beam-limiting aperture and the focusing power of the condenser lens 210. The condenser lens 210 may be an adjustable condenser lens that may be configured such that the position of a first principal plane is movable. The adjustable condenser lens may be configured to be magnetic, whereby the off-axis beamlets 212 and 213 may illuminate the source conversion unit 220 with a rotation angle. The rotation angle varies with the focusing power or the position of the first principal plane of the adjustable condenser lens. The focusing lens 210 may be an anti-rotation focusing lens that may be configured to keep the rotation angle constant while changing the focusing power of the focusing lens 210. In some embodiments, the focusing lens 210 may be an adjustable anti-rotation focusing lens whose rotation angle does not change as its focusing power and the position of its first principal plane change.

[0031]

[0043] The objective lens 231 may be configured to focus the beamlets 211, 212, and 213 onto the sample 208 for inspection, and in this embodiment may form three probe spots 221, 222, and 223 on the surface of the sample 208. The Coulomb aperture plate 271 is configured, in operation, to block peripheral electrons of the primary electron beam 202 to reduce the Coulomb effect, which may enlarge the size of the probe spots 221, 222, and 223 of the primary beamlets 211, 212, 213, respectively, and thus reduce the inspection resolution.

[0032]

[0044] The beam separator 233 may be, for example, a Wien filter including electrostatic deflectors generating electrostatic and magnetic dipole fields (not shown in FIG. 2). In operation, the beam separator 233 may be configured to exert an electrostatic force by the electrostatic dipole field on individual electrons of the primary beamlets 211, 212, and 213. The electrostatic force is equal in magnitude but opposite in direction to the magnetic force exerted by the magnetic dipole field of the beam separator 233 on the individual electrons. Thus, the primary beamlets 211, 212, and 213 may pass at least substantially straight through the beam separator 233 with at least substantially zero deflection angle.

[0033]

[0045] In operation, the deflection scanning unit 232 is configured to deflect the primary beamlets 211, 212, and 213 to scan the probe spots 221, 222, and 223 across respective scan areas within a section of the surface of the sample 208. In response to the incidence of the primary beamlets 211, 212, and 213 or the probe spots 221, 222, and 223 on the sample 208, electrons emerge from the sample 208 and generate three secondary electron beams 261, 262, and 263. Each of the secondary electron beams 261, 262, and 263 typically includes secondary electrons (having an electron energy of 50 eV or less) and backscattered electrons (having an electron energy between 50 eV and the landing energy of the primary beamlets 211, 212, and 213). The beam separator 233 is configured to deflect the secondary electron beams 261, 262, and 263 towards the secondary projection system 250. The secondary projection system 250 then focuses the secondary electron beams 261, 262, and 263 onto detector elements 241, 242, and 243 of the electron detection device 240. The detector elements 241, 242, and 243 are arranged to detect corresponding secondary electron beams 261, 262, and 263 and generate corresponding signals that are sent to the controller 109 or a signal processing system (not shown), for example to construct an image of a corresponding scan area of ​​the sample 208.

[0034]

[0046] In some embodiments, detector elements 241, 242, and 243 detect corresponding secondary electron beams 261, 262, and 263, respectively, and generate corresponding intensity signal outputs (not shown) to an image processing system (e.g., controller 109). In some embodiments, each detector element 241, 242, and 243 may include one or more pixels. The intensity signal output of a detector element may be the sum of signals generated by all the pixels in the detector element.

[0035]

[0047] In some embodiments, the controller 109 may comprise an image processing system comprising an image acquirer (not shown), a storage (not shown). The image acquirer may comprise one or more processors. For example, the image acquirer may include a computer, a server, a mainframe host, a terminal, a personal computer, any type of mobile computing device, etc., or a combination thereof. The image acquirer may be communicatively coupled to the electronic detection device 240 of the apparatus 104 via a medium, such as electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, Internet, wireless network, wireless communication, or a combination thereof, among others. In some embodiments, the image acquirer may receive signals from the electronic detection device 240 and may construct an image. The image acquirer may thus acquire an image of the sample 208. The image acquirer may also perform various post-processing functions, such as generating contour lines, overlaying indicators on the acquired image, etc. The image acquirer may be configured to make adjustments, such as brightness and contrast, of the acquired image. In some embodiments, the storage may be a storage medium, such as a hard disk, a flash drive, cloud storage, random access memory (RAM), other types of computer readable memory, etc. A storage may be coupled with the image acquirer and may be used to store raw scanned image data as original images and to store post-processed images.

[0036]

[0048] In some embodiments, the image acquirer may acquire one or more images of the sample based on an imaging signal received from the electronic detection device 240. The imaging signal may correspond to a scanning operation to perform charged particle imaging. The acquired image may be a single image including multiple imaging areas. The single image may be stored in storage. The single image may be an original image that may be divided into multiple regions. Each of these regions may include an imaging area that encompasses a feature of the sample 208. The acquired image may include multiple images of a single imaging area of ​​the sample 208 sampled multiple times in a time series. The multiple images may be stored in storage. In some embodiments, the controller 109 may be configured to perform an image processing step using multiple images of the same location of the sample 208.

[0037]

[0049] In some embodiments, the controller 109 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain a distribution of detected secondary electrons. The electron distribution data collected during the detection time window may be used in combination with corresponding scan path data of each of the primary beamlets 211, 212, and 213 incident on the wafer surface to reconstruct an image of the wafer structure during inspection. The reconstructed image may be used to reveal various features of the internal or external structure of the sample 208, thereby revealing defects that may be present in the wafer.

[0038]

[0050] In some embodiments, the controller 109 may control the motorized stage 209 to move the sample 208 during inspection of the sample 208. In some embodiments, the controller 109 may enable the motorized stage 209 to move the sample 208 continuously in one direction at a constant speed. In other embodiments, the controller 109 may enable the motorized stage 209 to vary the speed of movement of the sample 208 over time depending on the step of the scanning process.

[0039]

[0051] 2 shows that the apparatus 104 uses three primary electron beams, it will be understood that the apparatus 104 may use two or more primary electron beams, and this disclosure does not limit the number of primary electron beams used in the apparatus 104. In some embodiments, the apparatus 104 may be a SEM used for lithography.

[0040]

[0052] Compared to a single charged particle beam imaging system ("single beam system"), a multiple charged particle beam imaging system ("multi-beam system") may be designed to optimize throughput for different scan modes. The embodiments of the present disclosure provide a multi-beam system with the ability to optimize throughput for different scan modes by using beam arrays with different geometries to accommodate different throughput and resolution requirements.

[0041]

[0053] A non-transitory computer readable medium may be provided that stores instructions for a processor (e.g., the processor of controller 109 of Figures 1-2) to perform image processing, data processing, beamlet scanning, database management, graphical display, operation of a charged particle beam instrument or another imaging device, etc. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid state drives, magnetic tape or any other magnetic data storage medium, CD-ROMs, any other optical data storage medium, any physical medium with a pattern of holes, RAM, PROMs, and EPROMs, FLASH-EPROMs or any other flash memory, NVRAMs, caches, registers, any other memory chips or cartridges, and networked versions of the foregoing.

[0042]

[0054] Reference is now made to FIG. 3A, which is a schematic diagram illustrating an example fluid transfer system 300A that is part of the example multi-beam system of FIG. 2 consistent with an embodiment of the present disclosure. The fluid transfer system 300A may include a fluid cabinet 301 that transfers fluid (e.g., water, glycol, a mixture of water and glycol, etc.) in and out of an atmospheric fluid bath 303. The fluid cabinet 301 and fluid bath 303 may be components of the example multi-beam system of FIG. 2 or may be separate from the example multi-beam system of FIG. 2. The fluid cabinet 301 may include heat exchangers, pumps, valves, or other components that may be used to provide fluid to the wafer stage 307 for purposes such as cooling the wafer stage 307 or holding the wafer to the wafer stage 307. The wafer stage 307 may be the same component as the motorized stage 207 of FIG. 2.

[0043]

[0055] The fluid cabinet 301 may transfer fluid from the fluid reservoir 303 to a rigid tube 313 (e.g., metal). The rigid tube 313 may be connected to an outer flexible tube 315 (e.g., polyurethane) that may transfer fluid to the vacuum chamber 305 or to additional systems or components 309 inside or outside the system. Fluid may be transferred from the outer flexible tube 315 to an inner flexible tube 317 inside the vacuum chamber 305. The wafer stage 307 may be cooled by the fluid transferred through the inner flexible tube 317. Thus, fluid may be transferred through the inner flexible tube 317 to the outer flexible tube 315 outside the chamber 305, to the rigid tube 313, and back to the fluid cabinet 301 in a continuous cycle until cooling is completed and pump-down begins.

[0044]

[0056] Fluid moving through the rigid tube 313 may be retained in the rigid tube 313 due to its low permeability. Meanwhile, air molecules (e.g., O2, N2, etc.) in the atmospheric fluid reservoir 303 may allow the air molecules 311 to enter the vacuum chamber 305 from the inner flexible tube 317 by permeating the outer flexible tube 315. Also, due to the porosity and crystal structure of the outer flexible tube 315, the air molecules 311 may enter the vacuum chamber 305 from the inner flexible tube 317 by permeating the outer flexible tube 315. In ambient low pressure systems, the inner flexible tube 317 may be made of polytetrafluoroethylene (PTFE). However, PTFE may not be preferred for high and ultra-high vacuum applications, such as some embodiments of water cooling of high speed wafer stages of multi-beam systems. Due to the porosity and crystalline structure of PTFE, PTFE has a high permeability to air molecules, especially when a pressure gradient is established between the inside of inner flexible tube 317 and vacuum chamber 305. Thus, when PTFE is used for inner flexible tube 317 in high vacuum applications, air molecules may permeate into vacuum chamber 305.

[0045]

[0057] Reference is now made to Figure 3B, which is a schematic diagram illustrating an example fluid transfer system 300B that is part of the example multi-beam system of Figure 2 consistent with embodiments of the present disclosure. Fluid transfer system 300B may include components of fluid transfer system 300A of Figure 3A above and operate in a similar manner to fluid transfer system 300A.

[0046]

[0058] The fluid transfer system 300B may include a degassing system 320 located outside the vacuum chamber 305. In some embodiments, the degassing system 320 may be located inside the vacuum chamber 305. The degassing system 320 may be configured to receive the transfer fluid from the outer flexible tube 315 and remove air molecules 321 from the transfer fluid before the transfer fluid enters the inner flexible tube 317 inside the vacuum chamber 305. In some embodiments, a single degassing system may be located outside the fluid cabinet 301. In some embodiments, multiple degassing systems may be provided, one corresponding to each of the multiple outer flexible tubes 315. In some high and ultra-high vacuum applications, such as water cooling of a high speed wafer stage of a multi-beam system, the inner flexible tube 317 may be made of PTFE. The high permeability of PTFE to air molecules may result in no gas leakage into the chamber 305 because a degassing system 320 may remove gases (e.g., O2, N2, etc.) from the transfer fluid before it enters the vacuum chamber 305. In some embodiments, the inner flexible tube 317 may be a multi-layer fluid transfer tube (e.g., tube 600 of FIG. 6).

[0047]

[0059] Reference is now made to FIG. 3C, which is a schematic diagram illustrating an exemplary degassing system 320 that is part of the exemplary fluid transfer system 300B of FIG. 3B, and FIG. 3D, which is a diagram of a hollow fiber membrane tube 324, consistent with an embodiment of the present disclosure. As shown in FIG. 3C, the degassing system 320 may include a housing 322 that may include a plurality of hollow fiber membrane tubes 324 (e.g., polypropylene), a collection tube 323, and a baffle 327. The plurality of hollow fiber membrane tubes 324 may provide a large surface area for liquid-gas contact inside the housing 322. The transport fluid may flow from the outer flexible tube 315 into a fluid inlet 330 of the housing 322. The baffle 327 may direct the transport fluid to flow radially over the hollow fiber membrane tubes 324 to maximize the contact surface area between the membrane and the transport fluid. The transport fluid may flow through the collection tube 323 and around the exterior surface of the hollow fiber membrane tubes 324. The transfer fluid may flow through collection tube 323 to the outside of housing 322 through fluid outlet 331 into chamber 305 .

[0048]

[0060] The degassing system 320 may also include a vacuum pumping system 333. The vacuum pumping system 333 may be connected to the housing 322 via the gas outlet 332 such that gas may flow from inside the hollow fiber membrane tubes 324 to the gas outlet 332. For example, the vacuum pumping system 333 may be operated such that gas inside the hollow fiber membrane tubes 324 may flow in a countercurrent direction. The countercurrent flow of gas inside the hollow fiber membrane tubes 324 may offset the balance of the liquid and gas phases of the transport fluid to establish a pressure gradient between the inside and outside of the hollow fiber membrane tubes 324, where the inside of the hollow fiber membrane tubes 324 may have a lower pressure (or lower gas concentration) and the outside of the hollow fiber membrane tubes 324 may have a higher pressure (or higher gas concentration). In some embodiments, the hollow fiber membrane tubes 324 may be configured to extend in a direction perpendicular to the length of the housing 322 such that a baffle 327 is not required for the degassing system 320. In some embodiments, a strip gas may be applied to an additional inlet to the housing 322 to flow inside the hollow fiber membrane tubes 325 to improve the efficiency of gas removal of certain gas species. For example, applying a N2 strip gas may improve the efficiency of O2 removal from the transport fluid.

[0049]

[0061] 3D, a pressure gradient (or gas concentration gradient) established between the inside and outside of the hollow fiber membrane tube 324 may cause gas 325 dissolved in the transport fluid 326 to migrate from the outside (high pressure side) of the hollow fiber membrane tube 324 to the inside (low pressure side) of the hollow fiber membrane tube 324. The gas 325 (e.g., air molecules 321) may continue to migrate through the hollow fiber membrane tube 324 to the gas outlet 332 toward the vacuum pump system 333 (low pressure side).

[0050]

[0062] In some embodiments, the vacuum pump system 333 may be a vacuum pump. In some embodiments, the vacuum pump system 333 may be a compressed air driven vacuum pump. When the vacuum pump system 333 is a compressed air driven vacuum pump, the vacuum pump system 333 may compress air such that the compressed air flows through the opening of the gas outlet 332. The compressed air driven vacuum pump may operate according to Bernoulli's principle such that as the velocity of the compressed air increases, the pressure of the vacuum pump system 333 decreases to create a vacuum environment.

[0051]

[0063] In some embodiments, the degassing system 320 may include multiple degassing systems, one per outer flexible tube 315, to increase the efficiency of gas removal from the transfer fluid. In some embodiments, the flow rate of the transfer fluid may be adjusted to decrease the flow rate so that more dissolved gas may be removed from the transfer fluid. By decreasing the flow rate of the transfer fluid, the transfer fluid may spend more time in the degassing system 320, which may result in an increased amount of dissolved gas being removed from the transfer fluid.

[0052]

[0064] Reference is now made to FIG. 4A, which is a graph illustrating an exemplary relationship between time and pressure in a vacuum chamber (e.g., vacuum chamber 305 of FIG. 3A). As shown in FIG. 4A, the horizontal axis represents time and the vertical axis represents pressure in the vacuum chamber. Time 411 out of the 40 hours indicates a time when the system may stop the flow of circulating water, which represents still water inside the PTFE fluid transfer tube, as a test. The total pressure 401 in the vacuum chamber is shown along with H2O (water) partial pressure 403, N2 (air component) partial pressure 405, O2 (air component) partial pressure 407, and Ar (air component) partial pressure 409. It should be noted that under practical conditions, the system may not stop the flow of circulating water.

[0053]

[0065] As shown in FIG. 4A, at time 411, the water pressure 403 remains constant while the nitrogen partial pressure 405, oxygen partial pressure 407, and argon partial pressure 409 decrease. The decrease in the nitrogen, oxygen, and argon partial pressures at time 411 may indicate a decrease in the number of air molecules escaping the PTFE fluid transfer tubes and entering the surrounding vacuum chamber because the water circulation with the fluid cabinet (e.g., fluid cabinet 301 in FIG. 3A) is closed at time 411. As a result of the water circulation being closed, fewer air molecules may escape the PTFE fluid transfer tubes because the air molecules leave the system with the water and new air molecules cannot enter the system after the water circulation is closed. Thus, a high PTFE permeability of air molecules under a pressure gradient is seen in FIG. 4A.

[0054]

[0066] Reference is now made to FIG. 4B, which is a graph illustrating an exemplary relationship between time and pressure in a vacuum chamber (e.g., vacuum chamber 305 in FIG. 3B). The system may include a degassing system (e.g., degassing system 320 in FIG. 3B) between a fluid cabinet (e.g., fluid cabinet 301 in FIG. 3B) and the vacuum chamber. The system may include an outer flexible tube (e.g., outer flexible tube 315 in FIG. 3B) between the degassing system and the vacuum chamber. As shown in FIG. 4B, the horizontal axis represents time and the vertical axis represents pressure in the vacuum chamber. Period 431 indicates a period during which the system may stop the flow of circulating water to show still water inside the PTFE fluid transfer tube as a test. Period 432 indicates a period during which the system may start the flow of circulating water. Period 433 indicates a period during which the system may run the degassing system (e.g., degassing system 320 in FIG. 3B) while circulating water. The total pressure 421 in the vacuum chamber is shown along with N2 (a component of air) partial pressure 425, O2 (a component of air) partial pressure 427, and Ar (a component of air) partial pressure 428. Note that under practical conditions, the system cannot stop the flow of circulating water.

[0055]

[0067] 4B, when the degassing system is run during periods 432 and 433, the total pressure 421 and partial pressures 425, 427, and 428 decrease. The decrease in nitrogen, oxygen, and argon pressure at the beginning of period 433 may indicate a decrease in the number of air molecules entering the vacuum chamber because the degassing system at the beginning of period 433 may remove gas from the transfer fluid before it enters the vacuum chamber.

[0056]

[0068] 4B, the total pressure 421 may have similar values ​​during periods 431 and 433. These similar total pressure values ​​may indicate that a significant number of gas molecules are not entering the vacuum chamber through the outer flexible tube.

[0057]

[0069] Reference is now made to Figure 5, which is an illustration of permeation consistent with an embodiment of the present disclosure. Polymers may be permeable to fluids (e.g., gases, vapors, liquids, etc.) to varying degrees depending on the properties of the polymer (e.g., chemical composition, crystallinity, molecular weight, etc.) and the properties of the fluid (e.g., molecular size, polarity, etc.). Transport of molecules through a polymer may be induced by a pressure gradient, a temperature gradient, a concentration gradient, or by an external force field. For example, in high or ultra-high vacuum systems (e.g., vacuum chamber 305 in Figure 3A), transport of water and gas molecules from an inner flexible tube (e.g., inner flexible tube 317 in Figure 3A) to an outer flexible tube may be induced by a pressure gradient or a concentration gradient between the inside of the tube and the inside of the vacuum chamber.

[0058]

[0070] Fluid permeation through a polymer may include three steps: (1) dissolution (absorption) of molecules 501 or 503 into the membrane 513 of the polymer (e.g., inner flexible tube 317 in FIG. 3A) on the side of higher potential Phigh (e.g., inside inner flexible tube 317 in FIG. 3), (2) molecular diffusion of molecules in and through membrane 513, and (3) release (desorption) of the diffused molecules on the other side into a fluid at lower potential Pvacuum (e.g., vacuum chamber 305 in FIG. 3A). The term "permeation" describes the total mass transport of the permeating fluid across the membrane, whereas the term "diffusion" describes the movement of the permeating molecules inside the entire membrane.

[0059]

[0071] The permeability of a fluid to a polymer may depend on the polarity of the fluid and the polymer. A molecule may contain multiple bonds. If the electronegativity of two atoms sharing electrons is equal, the two atoms may form a non-polar bond. If the electronegativity of two atoms sharing electrons is not equal, the atoms are not shared equally and partial ionic charges may result. This unequal sharing of electrons results in a bond dipole and the bond formed is polar. If the bond dipoles present in a molecule do not cancel each other out, the molecule is polar. If the bond dipoles present in a molecule cancel each other out, the molecule is non-polar. Polar molecules attract and bond to other polar molecules due to their partial charges. Non-polar molecules are left behind to form groups with other non-polar molecules and form weak bonds with other non-polar molecules while polar molecules attract other polar molecules. Thus, polar molecules may easily permeate polar membranes but not non-polar membranes. Similarly, non-polar molecules may easily permeate non-polar membranes but not polar membranes.

[0060]

[0072] For example, molecule 501 may be polar (e.g., water), molecule 503 may be non-polar (e.g., N2, O2), and polymer membrane 513 may be non-polar. In a system with a pressure gradient Phigh to Pvacuum, polar molecule 501 may be retained on the high potential Phigh side of non-polar membrane 613, while non-polar molecule 503 may permeate non-polar membrane 513.

[0061]

[0073] Water vapor and air molecules in a vacuum chamber (e.g., vacuum chamber 305 in FIG. 3A) may be undesirable for several reasons. One is that the pressure in the vacuum chamber may need to reach a predetermined pressure before inspection of the wafer can occur. Water vapor and air molecules escaping from the flexible tube (e.g., inner flexible tube 317 in FIG. 3A) into the vacuum chamber may increase the pressure in the vacuum chamber, thereby preventing the vacuum chamber from dropping to the predetermined pressure required for inspection. The long time it takes for the system to reach the predetermined pressure (e.g., pump-down time) may reduce the availability of the system, as shown below, for example, by comparing curves 801-804A and 801-804B in FIG. 8. Water vapor and air molecules may also reduce the lifetime of the inspection system due to contaminant-sensitive components in the system (e.g., pure aluminum components, high voltage components, electron source, etc.). Therefore, the selection of materials for the flexible tube is essential to improve the throughput and lifetime of the inspection system.

[0062]

[0074] Reference is now made to Figure 6, which is an illustration of a multi-layer fluid transfer tube consistent with an embodiment of the present disclosure. As shown in Figure 6, fluid transfer tube 600 (e.g., inner flexible tube 317 of Figures 3A-3B) can comprise multiple tubular layers (such as layers 601, 602, or 603). It is understood that tube 600 is not limited to the illustrated embodiment and can comprise two layers or four or more layers (e.g., tubular layers).

[0063]

[0075] By effective pore penetration, coating flexible polymers with diamond-like carbon (DLC), ions, or high density polymers may provide a structure that is substantially impermeable to oxygen and water vapor while maintaining a flexible structure for high speed movement of the wafer stage during inspection. These coating materials may also be designed to improve conductivity or wear resistance. For example, some flexible polymers without coating (e.g., PTFE) may have high electron affinity and insulating properties that may pose electrostatic risks to the system due to high voltages during operation. A substantial reduction in the permeability of the fluid transport tubes may allow the system (e.g., vacuum chamber 305 in Figures 3A-3B) to reach lower pressures in addition to reducing the penetration of fluids (e.g., water, air, etc.) from inside the tube to outside the tube into the vacuum chamber.

[0064]

[0076] In some embodiments, tube 600 may comprise only two layers 601 and 602, where layer 601 is polar and layer 602 may be non-polar. This embodiment may be preferred to reduce absorption of water vapor or air molecules into tube 600, since water is polar and air molecules are non-polar. In some embodiments, layer 601 may be non-polar while layer 602 may be polar. For example, the polar layer may include at least one polyvinylidene chloride (PVDC) or ethylene vinyl alcohol (EVOH) layer. The non-polar layer may include at least one PTFE layer because PVDC and EVOH are polar molecules with low oxygen and water permeability coefficients (e.g., 0.00425-0.57 cm3-mm / m2-d-atm O2 and 0.025-0.913 g-mm / m2-d water for PVDC, and 0.01-0.15 cm3-mm / m2-d-atm O2 and 0.8-2.4 g-mm / m2-d water for EVOH). The non-polar layer may include at least one PTFE layer because PTFE is a non-polar molecule with low water permeability coefficients (e.g., 0.0045-0.30 g-mm / m2-d water).

[0065]

[0077] In some embodiments, the tube 600 may comprise three layers 601-603, where layer 601 is polar, layer 602 is an adhesive layer, and layer 603 is non-polar. In some embodiments, layer 601 may be non-polar while layer 603 is polar. In some circumstances, having at least three layers may be preferred to increase adhesion between layers 601 and 603, thereby increasing the robustness of the tube 600 and decreasing the permeability of the tube 600 to water vapor or air molecules. As explained above, water is polar and air molecules are non-polar. The polar layer may include at least one PVDC or EVOH layer since PVDC and EVOH are polar molecules. The non-polar layer may include at least one PTFE layer since PTFE is a non-polar molecule. The adhesive layer may include at least one polyimide layer.

[0066]

[0078] In some embodiments, the tube 600 may comprise two layers 601 and 602, with 602 coating 601. For example, layer 601 may comprise at least one flexible polymer base (e.g., PTFE, polyethylene terephthalate, etc.), and layer 602 may comprise a DLC coating, a metal coating (e.g., Cr, Al, etc.), a metal oxide coating (e.g., AlOx), a semi-metal oxide coating (e.g., SiOx), or a high density polymer coating (e.g., polyimide / Kapton, polyvinylidene fluoride, etc.). In some circumstances, this layer configuration may be preferred to reduce molecular diffusion of water vapor or air molecules in and through the tube 600. The coating layer 602 may reduce the tube 600 permeation of water vapor or air molecules in the diffusion stage of permeation by blocking the pores of layer 601. In some embodiments, layer 602 may include a DLC coating or a metal coating applied to layer 601 under a negative bias by inserting a conductive structure (e.g., a wire) into layer 601. A negative bias may be applied during plasma deposition of layer 602 to accelerate the coating of ions and to cause the coating ions to penetrate the top layer of layer 601, thereby blocking interstitial sites and pores of layer 601 and reducing fluid permeability to tube 600. In some embodiments, each of the DLC coating, metal coating, metal oxide coating, or semi-metal oxide coating may have a thickness of 10-50 nm so as not to affect the mechanical properties of tube 600. In some embodiments, tube 600 may include at least one adhesive layer. In some embodiments, at least one PVDC or EVOH layer may be inside or outside layer 601 and coating layer 602.

[0067]

[0079] Reference is now made to FIG. 7, which is a diagram of permeation consistent with embodiments of the present disclosure. Similar to FIG. 5, the environment may have polar molecules 701 and non-polar molecules 703. The polymer membrane 713 may include two or more layers, including a polar layer 715 and a non-polar layer 717. In a system with a pressure gradient Phigh to Pvacuum, the non-polar molecules 703 may be held on the high potential Phigh side of the polar layer 715, while the polar molecules 701 may permeate through the polar layer 715. However, the polar molecules 701 may be held on the polar layer 715 by the non-polar layer 717. Thus, the molecules 701 and 703 may be prevented from escaping to the low potential side Pvacuum of the membrane 713. In some embodiments, a layer containing non-polar (or hydrophobic) molecules (e.g., PTFE) may have a water contact angle greater than 90 degrees. In some embodiments, a layer containing polar (or hydrophilic) molecules (e.g., PVDC, EVOH, etc.) may have a water contact angle less than 90 degrees.

[0068]

[0080] Reducing the transmission of molecules 701 and 703 (e.g., water vapor, air molecules, etc.) may be advantageous in reducing the pressure in a vacuum chamber system (e.g., vacuum chamber 305 of FIGS. 3A-3B). The pressure in the vacuum chamber may be lower in systems where fluid or gas does not escape the fluid transfer tubes because the system pressure may increase with an increase in gas molecules in the system (e.g., curves 801-804B of FIG. 8). In systems where fluid or gas does not escape the fluid transfer tubes, the vacuum chamber pressure may reach a lower pressure in a shorter time because the system pressure may decrease with a decrease in the number of gas molecules. Reducing the vacuum chamber pressure in a shorter time may enable the charged particle system (e.g., EBI system 100 of FIG. 1) to use higher voltages sooner (e.g., line 813 of FIG. 8) and collect inspection measurements sooner (e.g., line 815 of FIG. 8). Reducing the vacuum chamber pressure in a shorter time may therefore optimize or extend the life of the inspection system. For example, using fluid transfer tubes that reduce the penetration of water vapor and air molecules into the vacuum chamber may reduce pump down time from 40 hours to 16 hours, and may extend the life of the inspection system by reducing the final vacuum chamber pressure.

[0069]

[0081] Reference is now made to Figure 8, which is a graph illustrating an exemplary relationship between time and pressure within a vacuum chamber (e.g., vacuum chamber 305 of Figures 3A-3B). As shown in Figure 8, the horizontal axis represents time in hours and the vertical axis represents pressure within the vacuum chamber. Curves 801A, 802A, 803A, and 804A are the measured pressures within the vacuum chamber when a PTFE tube is used for the flexible tube inside the vacuum chamber (e.g., inner flexible tube 317 of Figure 3) without a degassing system, while curves 801B, 802B, 803B, and 804B are the estimated pressures within the vacuum chamber when a multi-layer transfer tube (e.g., fluid transfer tube 600 of Figure 6) is used for the flexible tube inside the vacuum chamber or when a degassing system (e.g., degassing system 320 of Figure 3B) is used. Curves 801A and 801B are the total pressure in the vacuum chamber, curves 802A and 802B are the partial pressure of water in the vacuum chamber, curves 803A and 803B are the partial pressure of nitrogen in the vacuum chamber, and curves 804A and 804B are the partial pressure of oxygen in the vacuum chamber. As curves 801-804B show, the pressure in the vacuum chamber may be lower in a system using a multi-layer transfer tube that may use a combination of polar and non-polar layers because fluid or gas cannot escape the multi-layer transfer tube. The pressure in the vacuum chamber may also be lower in a system using a single-layer tube with a degassing system because dissolved gas may be removed from the transfer fluid before it enters the vacuum chamber. The pressure in the vacuum chamber may be lower in a system where fluid or gas cannot escape the multi-layer transfer tube because the system pressure may increase with an increase in gas molecules in the system, as shown by curves 801-804A. Similarly, the pressure in the vacuum chamber may be lower in systems where dissolved gases are removed from the transfer fluid before it enters the vacuum chamber. For example, as curves 803A and 804A show, gases (e.g., N2, O2, etc.) may escape from flexible tubing using PTFE if a degassing system is not used because PTFE is non-polar.Thus, as curves 802A and 802B show, water retention in flexible tubing may be the same if PTFE or multi-layer transfer tubing is used since PTFE is non-polar.

[0070]

[0082] Line 813 is the maximum pressure at which a charged particle system (e.g., EBI system 100 of FIG. 1) may use high voltage. Because the charged particle system may need to perform an inspection under high voltage, the faster the vacuum chamber pressure falls below line 813, the sooner the charged particle system may operate under high voltage and improve system throughput. Line 815 is the maximum pressure at which the charged particle system may collect inspection measurements. A multi-layer transfer tube including a combination of polar and non-polar layers, a single layer transfer tube with a degassing system, or a combination thereof may be desirable because the sooner the vacuum chamber pressure falls below line 815, the sooner the charged particle system may perform an inspection. Thus, system throughput may be improved if the vacuum chamber pressure reaches line 815 sooner. In systems where fluid or gas does not escape the fluid transfer tubes (e.g., curves 801-804B) or enter the vacuum chamber, the vacuum chamber pressure may reach a lower pressure in a shorter time (e.g., about 10 hours) because the system pressure may drop as the number of gas molecules decreases. Thus, if the gas molecules are retained in the fluid transfer tubes or removed from the transfer fluid prior to entering the vacuum chamber, the vacuum chamber pressure may reach a lower pressure in a shorter time (e.g., about 10 hours) compared to systems using conventional tubes (e.g., about 40 hours), thereby allowing the system to provide a greater throughput.

[0071]

[0083] As shown in FIG. 8, the selection of materials for the fluid transfer tubes, preferably materials that prevent fluids or gases (e.g., water vapor, air molecules) from escaping into the vacuum chamber, or the use of a degassing system, is important to optimize and extend the life of the inspection system.

[0072]

[0084] Reference is now made to FIG. 9, which is a flow chart of an exemplary method 900 of forming a fluid transfer tube consistent with an embodiment of the present disclosure.

[0073]

[0085] In step 901, a tube (e.g., inner flexible tube 317 of FIG. 3) in a chamber (e.g., vacuum chamber 305 of FIGS. 3A-3B) for transferring a fluid (e.g., water) between a stage (e.g., wafer stage 307 of FIGS. 3A-3B) and the outside of the chamber may be formed by forming a first layer of a first material (e.g., layer 601 of FIG. 6) that is a flexible polymer. The flexible polymer layer may be non-polar (e.g., PTFE).

[0074]

[0086] In step 903, forming the tube may further include forming a second layer of a second material (e.g., layer 602 in FIG. 6) on the first layer, where the second material may include a DLC coating, a metal coating (e.g., Cr, Al, etc.), a metal oxide coating (e.g., AlOx), a semi-metal oxide coating (e.g., SiOx), or a dense polymer coating (e.g., polyimide / Kapton, polyvinylidene fluoride, etc.). The second material may be configured to reduce tube permeation of fluids (e.g., water) or gases (e.g., N2, O2) in a molecular diffusion step by blocking pores in the flexible polymer.

[0075]

[0087] In step 905, a negative bias may be applied to the tube via the conductive structure during plasma deposition of the second layer to accelerate the coating of ions of the second material and to penetrate the top layer of the flexible polymer, thereby blocking interstitial sites and pores in the flexible polymer and reducing the fluid permeability to the tube. Reducing the fluid permeability to the tube may allow the vacuum chamber to reach a lower pressure in a shorter time, since the system pressure may be reduced by reducing the number of gas molecules, for example by preventing water vapor and air molecules from entering the vacuum chamber. Reducing the vacuum chamber pressure in a shorter time may optimize the inspection throughput of the inspection system by allowing the charged particle system (e.g., EBI system 100 of FIG. 1) to use higher voltages sooner and collect inspection measurements sooner.

[0076]

[0088] In step 907, forming the tube may further include forming a third layer of a third material (e.g., layer 603 of FIG. 6) on the first layer, where the third material may include a polar layer (e.g., PVDC, EVOH, etc.). Creating a third layer of a third polar material may further reduce the permeability of water vapor or air molecules into the tube by reducing absorption of the water vapor or air molecules into the tube, allowing the pressure in the vacuum chamber to be reduced in a shorter time.

[0077]

[0089] The embodiments may be further described using the following clauses. 1. A stage configured to secure a wafer; a chamber configured to house the stage, the chamber configured to operate in a vacuum environment; a tube disposed within the chamber and configured to transfer a fluid between the stage and an exterior of the chamber, the tube comprising: a first tubular layer of a first material that is a flexible polymer; and a second tubular layer of a second material configured to reduce tube permeation of fluids or gases. 2. The system of clause 1, wherein the flexible polymer comprises polytetrafluoroethylene (PTFE). 3. The system of clause 1, wherein the flexible polymer comprises polyethylene terephthalate (PET). 4. The system of any one of clauses 1 to 3, wherein the second tubular layer covers the first tubular layer. 5. The system of any one of clauses 1 to 4, wherein the second material is diamond-like carbon. 6. The system of any one of clauses 1 to 4, wherein the second material is a metal oxide. 7. The system of clause 6, wherein the metal oxide is aluminum oxide. 8. The system of any one of clauses 1 to 4, wherein the second material is a metal. 9. The system of clause 8, wherein the metal is aluminum. 10. The system of clause 8, wherein the metal is chromium. 11. The system of any one of clauses 1 to 4, wherein the second material is a semi-metal oxide. 12. The system of clause 11, wherein the semi-metal oxide is silicon oxide. 13. The system of any one of clauses 1 to 4, wherein the second material is a polymer. 14. The system of clause 13, wherein the polymer is a polyimide. 15. The system of clause 13, wherein the polymer is at least one of polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), or ethylene vinyl alcohol (EVOH). 16. The system of any one of clauses 5 to 12, wherein the second tubular layer has a thickness of 10 to 50 nanometers. 17. The system of any one of clauses 1, 2, or 4 to 16, wherein the tube further comprises a third tubular layer of a third material configured to reduce tube permeation of gas. 18. The system of clause 17, wherein a third tubular layer covers the second tubular layer. 19. The system of clause 17, wherein the first tubular layer covers the third tubular layer. 20. The system of any one of clauses 1, 2, or 4 through 19, wherein the first tubular layer comprises a fluid contact angle greater than 90 degrees. 21. The system of any one of clauses 1, 2, or 4 through 20, wherein the third tubular layer comprises a fluid contact angle less than 90 degrees. 22. The system of any one of clauses 1 to 21, wherein the tube further comprises an adhesive layer. 23. The system of clauses 1 to 22, further comprising an adhesive layer between each of the first tubular layer, the second tubular layer, or the third tubular layer. 24. The system of clause 22 or 23, wherein the adhesive layer comprises polyimide. 25. A system according to any one of clauses 17 to 24, wherein the third material comprises PVDC. 26. The system of any one of clauses 17 to 24, wherein the third material comprises EVOH. 27. A system according to any one of clauses 1 to 26, wherein the tube is configured to transport fluids in a high or ultra-high vacuum system. 28. The system of any one of clauses 1 to 27, wherein the first tubular layer comprises a plurality of first tubular layers. 29. The system of any one of clauses 1 to 28, wherein the second tubular layer comprises a plurality of second tubular layers. 30. The system of any one of clauses 17 to 29, wherein the third tubular layer comprises a plurality of third tubular layers. 31. The system of any one of clauses 1 to 30, wherein the fluid comprises at least one of water or glycol. 32. A system according to any one of clauses 1 to 31, wherein the gas comprises at least one of oxygen or nitrogen. 33. The system A fluid tank; a plurality of rigid tubes external to the chamber for transferring fluid between the fluid reservoir and a plurality of polyurethane tubes external to the chamber; 33. The system of any one of clauses 1 to 32, wherein a tube disposed within the chamber is configured to transfer fluid between the plurality of polyurethane tubes and the stage. 34. The stage is configured to move within the chamber; 34. The system of any one of clauses 1 to 33, wherein the tube is configured to move with the stage. 35. A system according to any one of clauses 1 to 34, wherein the system comprises a scanning electron microscope system. 36. The system of any one of clauses 1 to 35, wherein the system comprises a lithography system. 37. A system according to any one of clauses 1 to 36, wherein the tube comprises a plurality of tubes. 38. A tube provided within the vacuum chamber and configured to transfer a fluid between the stage and an exterior of the vacuum chamber, comprising: a first tubular layer of a first material that is a flexible polymer; and a second tubular layer of a second material configured to reduce fluid or gas permeation through the tube. 39. The tube of clause 38, wherein the flexible polymer comprises polytetrafluoroethylene (PTFE). 40. The tube of clause 38, wherein the flexible polymer comprises polyethylene terephthalate (PET). 41. The tube of any one of clauses 38 to 40, wherein a second tubular layer covers the first tubular layer. 42. The tube of any one of clauses 38 to 41, wherein the second material is diamond-like carbon. 43. A tube according to any one of clauses 38 to 41, wherein the second material is a metal oxide. 44. The tube of clause 42, wherein the metal oxide is aluminum oxide. 45. A tube according to any one of clauses 38 to 41, in which the second material is a metal. 46. ​​A tube as referred to in clause 45, the metal being aluminium. 47. A tube as referred to in clause 45, the metal being chromium. 48. A tube according to any one of clauses 38 to 41, wherein the second material is a semi-metal oxide. 49. The tube of clause 47, wherein the semi-metal oxide is silicon oxide. 50. The tube of any one of clauses 38 to 41, wherein the second material is a polymer. 51. The tube of clause 50, wherein the polymer is a polyimide. 52. The tube of clause 50, wherein the polymer is at least one of polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), or ethylene vinyl alcohol (EVOH). 53. A tube according to any one of clauses 42 to 49, wherein the thickness of the second tubular layer is between 10 and 50 nanometers. 54. The tube of any one of clauses 38, 39, or 41 to 53, wherein the tube further comprises a third tubular layer of a third material configured to reduce tube permeation of gas. 55. The tube of clause 54, wherein a third tubular layer covers the second tubular layer. 56. The tube of clause 54, wherein the first tubular layer covers the third tubular layer. 57. The tube of any one of clauses 38, 39, or 41 to 56, wherein the first tubular layer comprises a fluid contact angle greater than 90 degrees. 58. The tube of any one of clauses 38, 39, or 41 to 57, wherein the third tubular layer comprises a fluid contact angle less than 90 degrees. 59. The tube of any one of clauses 38, 39, or 41 to 58, wherein the tube further comprises an adhesive layer. 60. The tube of any one of clauses 38 to 59, further comprising an adhesive layer between each of the first tubular layer, the second tubular layer, or the third tubular layer. 61. The tube of clause 59 or 60, wherein the adhesive layer comprises polyimide. 62. A tube according to any one of clauses 54 to 61, wherein the third material comprises PVDC. 63. A tube according to any one of clauses 54 to 61, wherein the third material comprises EVOH. 64. A tube according to any one of clauses 38 to 63, wherein the tube is configured to transfer fluids in a high or ultra-high vacuum system. 65. The tube of any one of clauses 38 to 64, wherein the first tubular layer comprises a plurality of first tubular layers. 66. The tube of any one of clauses 38 to 65, wherein the second tubular layer comprises a plurality of second tubular layers. 67. The tube of any one of clauses 54 to 66, wherein the third tubular layer comprises a plurality of third tubular layers. 68. A tube according to any one of clauses 38 to 67, wherein the fluid comprises at least one of water or glycol. 69. A tube according to any one of clauses 38 to 68, in which the gas comprises at least one of oxygen or nitrogen. 70. A method of forming a tube for use in a vacuum chamber to transfer a fluid between a stage and an exterior of the vacuum chamber, comprising: forming a first tubular layer of a first material, the first material being a flexible polymer; forming a second tubular layer of a second material configured to reduce tube permeation of fluids or gases; and The method includes applying a negative bias to the tube via the conductive structure during plasma deposition of the second tubular layer. 71. The method of clause 70, wherein the first tubular layer comprises polytetrafluoroethylene (PTFE). 72. The method of clause 70, wherein the first tubular layer comprises polyethylene terephthalate (PET). 73. The method of any one of clauses 70 to 72, wherein forming the second tubular layer comprises coating the first tubular layer. 74. The method of any one of clauses 70 to 73, wherein the second material is diamond-like carbon. 75. The method of any one of clauses 70 to 73, wherein the second material is a metal oxide. 76. The method of claim 74, wherein the metal oxide is aluminum oxide. 77. The method of any one of clauses 70 to 73, wherein the second material is a metal. 78. The method of clause 77, wherein the metal is aluminum. 79. The method of clause 77, wherein the metal is chromium. 80. The method of any one of clauses 70 to 73, wherein the second material is a semi-metal oxide. 81. The method of claim 80, wherein the metalloid oxide is silicon oxide. 82. The method of any one of clauses 70 to 73, wherein the second material is a polymer. 83. The method of clause 82, wherein the polymer is a polyimide. 84. The method of clause 82, wherein the polymer is at least one of polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), or ethylene vinyl alcohol (EVOH). 85. The method of any one of clauses 70 to 84, wherein the second tubular layer has a thickness of 10 to 50 nanometers. 86. The method of any one of clauses 70, 71, or 73-85, further comprising forming a third tubular layer on the tube of a third material configured to reduce tube permeation of gas. 87. The method of clause 86, wherein a third tubular layer covers the second tubular layer. 88. The method of clause 86, wherein the first tubular layer covers the third tubular layer. 89. The method of any one of clauses 70, 71, or 73-88, wherein the first tubular layer comprises a fluid contact angle greater than 90 degrees. 90. The method of any one of clauses 70, 71, or 73-89, wherein the third tubular layer comprises a fluid contact angle less than 90 degrees. 91. The method of any one of clauses 70 to 90, further comprising forming an adhesive layer on the tube. 92. The method of any one of clauses 70 to 91, further comprising forming an adhesive layer between each of the first tubular layer, the second tubular layer, or the third tubular layer. 93. The method of clause 91 or 92, wherein the adhesive layer comprises a polyimide. 94. The method of any one of clauses 86 to 93, wherein the third material comprises PVDC. 95. The method of any one of clauses 86 to 93, wherein the third material comprises EVOH. 96. The method of any one of clauses 70 to 95, wherein the tube is configured to transfer fluids in a high or ultra-high vacuum system. 97. The method of any one of clauses 70 to 96, wherein forming the first tubular layer includes forming a plurality of first tubular layers. 98. The method of any one of clauses 70 to 97, wherein forming the second tubular layer includes forming a plurality of second tubular layers. 99. The method of any one of clauses 70 to 98, wherein forming the third tubular layer includes forming a plurality of third tubular layers. 100. The method of any one of clauses 70 to 99, wherein the fluid comprises at least one of water or glycol. 101. The method of any one of clauses 70 to 100, wherein the gas comprises at least one of oxygen or nitrogen. 102. A system according to any one of clauses 1 to 37, wherein the tube is a first tube. 103. A housing configured to receive a fluid, the housing comprising a plurality of second tubes; 13. The system of claim 102, further comprising a degassing system comprising: a vacuum system configured to remove gas from the fluid before the fluid enters the first tube. 104. A system as referred to in clause 103, in which the vacuum system comprises a vacuum pump. 105. A system according to clause 104, in which the vacuum pump is compressed air driven. 106. The system of any one of clauses 102 to 105, wherein the removed gas flows from the inside of the plurality of second tubes to a vacuum system. 107. The system of any one of clauses 102 to 106, wherein the fluid flows outside the plurality of second tubes. 108. The system of any one of clauses 102 to 107, wherein the plurality of second tubes comprises hollow fiber membranes. 109. The system of clause 108, in which the hollow fiber membrane comprises polypropylene. 110. The first tube comprises a first tubular layer of a first material that is a flexible polymer; 1. A system according to any one of clauses 102 to 109. 111. A stage configured to secure a wafer; a chamber configured to house the stage, the chamber configured to operate in a vacuum environment; a first tube disposed within the chamber and configured to transfer a fluid between the stage and an exterior of the chamber; a housing configured to receive a fluid, the housing comprising a plurality of second tubes; A system comprising: a degassing system; and a vacuum system configured to remove gas from the fluid before the fluid enters the first tube. 112. A system as referred to in clause 111, in which the vacuum system comprises a vacuum pump. 113. A system as claimed in clause 112, in which the vacuum pump is compressed air driven. 114. A system according to any one of clauses 111 to 113, wherein the removed gas flows from the inside of the plurality of second tubes to a vacuum system. 115. The system of any one of clauses 111 to 114, wherein the fluid flows outside the plurality of second tubes. 116. The system of any one of clauses 111 to 115, wherein the plurality of second tubes comprises hollow fiber membranes. 117. The system of clause 116, in which the hollow fiber membrane comprises polypropylene. 118. The first tube comprises a first tubular layer of a first material that is a flexible polymer; 1. A system according to any one of clauses 111 to 117. 119. The system of clause 118, wherein the first tube further comprises a second tubular layer of a second material configured to reduce first tube permeation of fluid or gas. 120. A system of any one of clauses 1 to 37 or 102 to 110, wherein the system includes an extreme ultraviolet inspection system. 121. A system of any one of clauses 1 to 37 or 102 to 110, where the system includes a deep ultraviolet inspection system. 122. A system of any one of clauses 1 to 37 or 102 to 110, wherein the system includes an x-ray.

[0078]

[0090] It will be understood that the embodiments of the present disclosure are not limited to the exact configurations described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope thereof.

Claims

1. a stage configured to secure the wafer; a chamber configured to house a stage, the chamber configured to operate in a vacuum environment; a first tube disposed within the chamber and configured to transfer a fluid between the stage and an exterior of the chamber; 1. A degassing system comprising: a housing configured to receive a fluid, the housing comprising a plurality of second tubes; a vacuum system configured to remove gas from the fluid before the fluid enters the first tube; and A system equipped with.

2. The system of claim 1 , wherein the vacuum system comprises a vacuum pump.

3. The system of claim 2 , wherein the vacuum pump is air driven.

4. The system of claim 1 , wherein the removed gas flows from inside the plurality of second tubes to a vacuum system.

5. The system of claim 1 , wherein the fluid flows outside the plurality of second tubes.

6. The system of claim 1 , wherein the plurality of second tubes comprises hollow fiber membranes.

7. The system of claim 6 , wherein the hollow fiber membranes comprise polypropylene.

8. the first tube comprises a first tubular layer of a first material that is a flexible polymer; A system according to any one of claims 1 to 3.

9. The system of claim 8 , wherein the first tube further comprises a second tubular layer of a second material configured to reduce permeation of fluids or gases through the first tube.

10. The system of claim 1 , wherein the system comprises an extreme ultraviolet inspection system.

11. The system of claim 1 , wherein the system comprises a deep ultraviolet inspection system.

12. The system of claim 1 , wherein the system includes an x-ray.

13. The system of claim 9 , wherein the second tubular layer covers the first tubular layer.

14. 10. The system of claim 9, wherein the tube further comprises a third tubular layer of a third material configured to reduce tube permeation of gas.

15. The system of claim 14 , further comprising an adhesive layer between each of the first tubular layer, the second tubular layer, or the third tubular layer.

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