Systems and methods for charged particle immersion to enhance voltage contrast defect signals

Abstract

Systems and methods for implementing charged particle immersion in a charged particle beam device are disclosed. According to particular embodiments, a charged particle beam system includes a charged particle source and a controller that controls the charged particle beam system to emit a charged particle beam in a first mode in which the beam is defocused and in a second mode in which the beam is focused on a surface of a sample.

Description

[0001] This application is a divisional application of the application filed on July 18, 2018, with application number 2018800506880 and entitled "System and method for immersing charged particles to enhance voltage contrast defect signals". Technical Field

[0002] This disclosure generally relates to the field of charged particle beam devices, and more specifically, to systems and methods for implementing charged particle flooding in charged particle beam devices. Background Technology

[0003] In the manufacturing process of integrated circuits (ICs), unfinished or finished circuit components are inspected to ensure they are manufactured according to design and free of defects. Inspection systems using optical microscopes typically have a resolution of several hundred nanometers, which is limited by wavelength. As the physical size of IC components continues to shrink to below 100 nanometers and even below 10 nanometers, inspection systems with higher resolution than optical microscopes are needed. Furthermore, electrical defects on wafers (such as open-circuit contact failures, open / short circuit wiring failures, etc.) cannot be detected by optical inspection.

[0004] Charged particle (e.g., electron) beam microscopy (such as scanning electron microscopy (SEM), with resolution less than nanometers) serves as a practical tool for inspecting IC components on wafers with feature sizes ranging from less than 100 nanometers. With SEM, electrons from a primary electron beam (electron beam) can be focused onto a probe spot on the wafer being inspected. The interaction of the primary electrons with the wafer generates one or more secondary electron beams. These secondary electron beams may include backscattered electrons, secondary electrons, or Auger electrons, generated by the interaction of the primary electrons with the wafer. The intensity of one or more secondary electron beams can vary based on the characteristics of the wafer's internal and / or external structures, thereby indicating whether the wafer contains defects.

[0005] The intensity of the secondary electron beam can be determined using a detection device or detector. The secondary electron beam can form one or more beam spots at predetermined locations on the detector surface. The detector can generate an electrical signal (e.g., current, voltage, etc.) representing the intensity of the detected secondary electron beam. This electrical signal can be measured by a measurement circuit device (e.g., an analog-to-digital converter) to obtain the distribution of the detected electrons. The electron distribution data collected during the detection time window, combined with the corresponding scan path data of the primary electron beam incident on the wafer surface, can be used to reconstruct an image of the inspected wafer structure. The reconstructed image can be used to reveal various features of the wafer's internal and / or external structure and can be used to reveal any defects that may be present in the wafer.

[0006] Furthermore, voltage contrast methods using charged particle inspection systems can be used to detect physical and electrical defects on wafers. To detect voltage contrast defects, a process called pre-charging is typically employed, in which charged particles are applied to the area to be inspected before inspection. The advantages of pre-charging include: 1) reducing the charging of wafer surfaces that would cause defocusing and distortion of the image; and 2) enabling the application of appropriate voltages to wafer features so that defects and surrounding non-defective features behave differently during inspection. In addition, pre-charging enhances the voltage contrast signal of defects, allowing for a satisfactory signal-to-noise ratio (SNR) in charged particle inspection systems and facilitating defect detection.

[0007] Currently, dedicated electron beam immersion guns are used as useful tools for pre-charging wafer surfaces and setting charging conditions. These guns enhance voltage contrast defect signals, thereby increasing defect detection sensitivity and / or throughput. During immersion, the gun provides a relatively large number of electrons to charge a predetermined area. Subsequently, the primary electron source of the electron beam inspection system is used to scan the pre-charged area to achieve imaging.

[0008] While traditional immersion guns can generate large charged particle currents and immerse the entire wafer in a short time, they face limitations in charged particle beam inspection applications. For example, in charged particle beam inspection of small memory devices, the small size of the inspection area negates the advantages of traditional immersion guns. Immersion guns also face limitations due to their independence from the charged particle source of the inspection system. Furthermore, the system needs to switch between two different operating modes: one for immersion and one for inspection. Since both operating modes operate at high voltage, switching one on and off the other is time-consuming and introduces system design complexity.

[0009] Furthermore, conventional immersion guns are typically limited by cost and are sub-components of other subsystems within electron beam inspection systems. Therefore, compared to, for example, the primary beam system of SEM, conventional immersion guns have simpler control. Consequently, immersion guns exhibit limited controllability and low precision. Moreover, attempting to overcome these limitations by modifying dedicated immersion guns to achieve greater precise controllability may be impractical due to cost constraints. Additionally, packaging limitations restrict the amount of possible modifications that dedicated immersion guns can make within the space occupied by charged particle beam inspection systems.

[0010] The information disclosed in this Background section is intended only to enhance the understanding of the background art of this disclosure and should not be construed as an admission or any form of advice that constitutes prior art known to those skilled in the art. For example, the limitations and disadvantages of related art described above are considered to be matters that the inventors had addressed in order to arrive at the inventive concept, or matters that were discovered during the conceiving of this disclosure. Therefore, the above description cannot simply be considered as information known to the public prior to the filing of this application. Summary of the Invention

[0011] Embodiments of this disclosure provide systems and methods for providing an inspection mode while simultaneously providing a charged particle immersion mode in a charged particle beam inspection apparatus.

[0012] In some embodiments, a charged particle beam system is provided, comprising a charged particle source configured to emit a charged particle beam along an optical axis, at least one aperture configured to allow the charged particle beam to pass through, and a controller. The controller may be configured to control the charged particle beam system to emit the charged particle beam in a first mode, in which the charged particle beam is incident on a sample at a first current level and is defocused. The controller may also be configured to control the charged particle beam system to emit the charged particle beam in a second mode, in which the charged particle beam is incident on the sample at a second current level and is focused onto the surface of the sample. The controller may also be configured to switch the charged particle beam system between the first mode and the second mode.

[0013] In some embodiments, a method is provided for examining a sample using a charged particle beam system. The method may include emitting a charged particle beam incident on the sample at a first current level, wherein the charged particle beam is defocused on the sample surface. The method may also include emitting a charged particle beam incident on the sample at a second current level, wherein the charged particle beam is focused on the sample surface.

[0014] Additional objects and advantages of the disclosed embodiments will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments. The objects and advantages of the disclosed embodiments may be realized and obtained by means of the elements and combinations set forth in the claims. However, exemplary embodiments of this disclosure are not required to achieve these exemplary objects and advantages, and some embodiments may not achieve any of the stated objects and advantages.

[0015] It should be understood that the general description above and the detailed description below are exemplary and illustrative only, and do not limit the subject matter of the disclosure. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating an exemplary electron beam inspection (EBI) system consistent with embodiments of the present disclosure.

[0017] Figure 2 The embodiments shown are consistent with those of this disclosure. Figure 1 A schematic diagram of an exemplary single-beam electron beam tool, which is part of an exemplary electron beam inspection system.

[0018] Figure 3 The embodiments shown are consistent with those of this disclosure. Figure 1 A schematic diagram of an exemplary multi-beam electron beam tool, which is part of an exemplary electron beam inspection system.

[0019] Figure 4 This is a schematic diagram illustrating an exemplary selective variable aperture consistent with embodiments of the present disclosure.

[0020] Figure 5 This is a schematic diagram illustrating an exemplary electron beam tool operating in defocus mode, consistent with embodiments of the present disclosure.

[0021] Figure 6 This is a schematic diagram illustrating an exemplary electron beam tool operating in imaging mode, consistent with embodiments of the present disclosure.

[0022] Figure 7 This is a schematic diagram illustrating an exemplary single-beam charged particle beam tool operating in a first mode consistent with embodiments of the present disclosure.

[0023] Figure 8 This is a schematic diagram illustrating an exemplary single-beam charged particle beam tool operating in a second mode consistent with embodiments of the present disclosure.

[0024] Figure 9 This is a schematic diagram illustrating an exemplary single-beam charged particle beam tool operating in a hybrid mode, consistent with embodiments of this disclosure.

[0025] Figure 10 This is a flowchart illustrating an exemplary method for inspecting a wafer, consistent with embodiments of this disclosure. Detailed Implementation

[0026] Various exemplary embodiments of the present disclosure will now be described more fully with reference to the accompanying drawings, in which some exemplary embodiments of the invention are illustrated. All descriptions and drawings of the embodiments will be exemplarily referenced to electron beams without limiting the scope of the invention.

[0027] This document discloses detailed embodiments of the present invention. However, the specific structural and functional details disclosed herein are for the purpose of describing exemplary embodiments of the present invention only. The invention may be embodied in many alternative forms and should not be construed as being limited to the embodiments explicitly stated herein.

[0028] Therefore, while various modifications and substitutions are possible with respect to the exemplary embodiments of this disclosure, those embodiments are shown by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that the exemplary embodiments of the invention are not intended to be limited to the specific forms disclosed; rather, the exemplary embodiments of the invention will cover all modifications, equivalents, and substitutions falling within the scope of the invention. Similar numerals denote similar elements in the description of the accompanying drawings.

[0029] While several exemplary ranges of values ​​are discussed herein, it should be understood that these ranges are merely examples. Specific embodiments consistent with this disclosure may operate outside these ranges.

[0030] In this disclosure, the axial direction can represent the optical axis direction of the device, while the radial direction can represent the direction perpendicular to the optical axis. The X and Y axes of the coordinate system should be understood as two perpendicular directions on the wafer plane.

[0031] The conjunction "or" includes any and all combinations of one or more of the listed elements associated with the conjunction. For example, the phrase "a device comprising A or B" could mean a device comprising A (where B is not present), a device comprising B (where A is not present), or a device in which both A and B are present. The phrases "at least one of A, B, ... and N" or "at least one of A, B, ... and N or combinations thereof" are most broadly defined as representing one or more elements selected from the group comprising A, B, ... N, that is, combinations of one or more of A, B, ... N, including any single element or in combination with one or more other elements, which may also include additional elements not listed.

[0032] In one exemplary method, an electron beam is used to immerse the surface of a wafer being inspected in a SEM tool. Immersion can be used to enhance the voltage contrast signal of defects to achieve a satisfactory signal-to-noise ratio (SNR) level, making defects easily detectable during the SEM inspection process.

[0033] In one exemplary embodiment, the primary electron beam of the SEM tool is used to replace the discrete immersion guns in the system to immerse the wafer surface. Immersion can be used to precharge the wafer in preparation for inspection by the SEM tool. Precharging can be used to enhance voltage-contrast defect signals, for example, as discussed in U.S. Patent Nos. 8,748,815 and 8,759,762, both of which are incorporated herein by reference in their entirety.

[0034] In simple terms, pre-charging can be implemented in various scenarios, including pre-scanning, defocus pre-scanning, and immersion. For example, pre-scanning can be used. In pre-scanning, the same current settings used in imaging are applied to the pre-scanning region, among other things. However, during pre-scanning, image data is ignored in the beam scanning region until image scanning begins and the image signal is collected.

[0035] In addition, defocus pre-scanning can be used. In defocus pre-scanning, the same current setting used during imaging can be used. During pre-scanning, the beam is defocused. Because the beam is defocused, the current density incident on the sample is reduced, which allows for the use of a slightly larger total current beam. Therefore, defocus pre-scanning can be more efficient than non-defocus pre-scanning. Although a slightly larger current beam can be used, the current level may still be limited due to the current requirements of imaging.

[0036] In addition, immersion can be used. Immersion allows a relatively large area to be pre-charged, which can result in better efficiency in some applications.

[0037] In one exemplary embodiment of this disclosure, an electron beam source equipped with adjustable apertures is provided, such as an aperture set in front of the tip of the electron beam source (in the direction of electron beam radiation). The aperture set may include at least one or more aperture holes for adjusting the desired beam current (dose) for an immersion function.

[0038] In one exemplary embodiment of this disclosure, a method is provided for using native electro-optics of a SEM, combining a condenser lens and an objective lens to form a beam spot size required for immersion. The primary beam of the SEM can be used for imaging and immersion.

[0039] The electron beam dose can be adjusted by selecting the desired aperture. The current range can be set to multiple levels (e.g., in the µA range) within the maximum available beam current that the electron beam source can provide. That is, the current of the electron beam applied to the wafer can be adjusted by selecting the corresponding aperture. For example, an aperture configured to emit a beam on the order of 1 µA can be used for electron beam immersion. An aperture configured to emit a beam in the range of 0.1 to 200 nA can be used for inspection. The range of possible emission currents used in both modes allows for a high level of adjustability. The current range used for immersion may overlap with the current range used for inspection. Therefore, in some embodiments, the maximum inspection current may be greater than the minimum immersion current. For example, the immersion current range may be set to 80 to 1500 nA.

[0040] The beam spot size can be, but is not limited to, submicron to millimeter (10^-4 to 10^0 mm). In some embodiments, the range of beam spot sizes available for tunable apertures can be from 5 µm to 1 mm. A beam with an appropriate spot size can then be used to immerse the wafer surface.

[0041] A larger beam size helps reduce the current density of the electron beam applied to the wafer. For example, a typical immersion gun is configured to emit a 100µA beam, resulting in a very large beam size. However, in electron beam inspection tools such as SEM tools, the field of view (FOV) is limited, so immersing a large area of ​​the wafer is not necessary. Furthermore, allowing adjustability to provide a smaller beam size for more precise charge control can be advantageous. That is, an ideal beam size can be selected to generate appropriate charging conditions for certain inspection applications, thereby allowing for more efficient wafer processing while avoiding charging areas outside the inspection area.

[0042] Depending on the application requirements, the setting of the electron beam source aperture can be combined with the setting of the column aperture to form an optimized immersion beam current density with the shortest switching time.

[0043] Now for reference Figure 1 This illustrates an exemplary electron beam inspection (EBI) system 100 consistent with embodiments of this disclosure. For example... Figure 1 As shown, the EBI system 100 includes a main chamber 101, a loading / locking 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 electron beam tool 104 can be a single-beam system or a multi-beam system. A controller 109 is electrically connected to the electron beam tool 104. The controller 109 can be a computer configured to perform various controls of the EBI system.

[0044] EFEM 106 includes a first loading port 106a and a second loading port 106b. EFEM 106 may include additional loading ports. The first loading port 106a and the second loading port 106b can receive a front-open wafer transfer cassette (FOUP) containing a wafer to be inspected (e.g., a semiconductor wafer or a wafer made of other materials) or a sample (wafers and samples are collectively referred to below as “wafers”). One or more robotic arms (not shown) in EFEM 106 can transport the wafer to loading / locking chamber 102.

[0045] Loading / locking chamber 102 is connected to a loading / locking vacuum pump system (not shown), which removes gas molecules from loading / locking chamber 102 to achieve a first pressure below atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) can transport the wafer from loading / locking chamber 102 to main chamber 101. Main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules from main chamber 101 to achieve a second pressure below the first pressure. After reaching the second pressure, the wafer is immersed in or inspected by an electron beam tool 104.

[0046] Figure 2A single-beam device is shown, wherein the inspection system includes a single primary beam configured to generate a secondary beam. (See diagram.) Figure 2 In the illustrated embodiment, the detector may be placed along the optical axis. In some embodiments, the detector may be arranged off-axis.

[0047] like Figure 2 As shown, the electron beam tool 104 includes a wafer holder 136 supported by a motorized stage 134 to hold a wafer 150 to be inspected. The electron beam tool 104 includes an electron emitter that may include a cathode 103, an anode 120, and a gun aperture 122. The electron beam tool 104 also includes a beam-limiting aperture 125, a condenser lens 126, a pillar aperture 135, an objective lens assembly 132, and an electron detector 144. In some embodiments, the objective lens assembly 132 is a modified SORIL lens that includes an electrode 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. During general imaging, an electron beam 161 emitted from the tip of the cathode 103 is accelerated by the voltage of the anode 120, passes through the gun aperture 122, the beam-limiting aperture 125, the condenser lens 126, and is focused onto a probe spot by the modified SORIL lens before impacting the surface of the wafer 150. Secondary electrons emitted from the wafer surface are collected by electron detector 144 to form an image of the region of interest.

[0048] The condenser lens and illumination optics of an electron beam tool may include or be supplemented by an electromagnetic quadrupole electron lens. For example, such as Figure 2 As shown, the electron beam tool 104 includes a first quadrupole lens 148 and a second quadrupole lens 158. In some embodiments, the quadrupole lenses are used to control the electron beam. For example, the first quadrupole lens 148 can be controlled to adjust the beam current, and the second quadrupole lens 158 can be controlled to adjust the beam spot size and beam shape.

[0049] although Figure 2 Electron beam tool 104 is shown as a single-beam inspection tool that uses only one primary electron beam to scan one location on wafer 150 at a time, but electron beam tool 104 can also be a multi-beam inspection tool that uses multiple primary electron beams to scan multiple locations on wafer 150 simultaneously.

[0050] For example, Figure 3 A multi-beam apparatus for directing multiple beams from a primary beam source to a sample using a beam splitter is illustrated. It should be readily understood that embodiments of this disclosure can also be applied to single-beam apparatuses.

[0051] like Figure 3As shown, the electron beam tool 204 includes a stage 134 and a wafer holder 136 supported by the stage 134 to hold a wafer 150 to be inspected. The electron beam tool 204 includes an electron emitter, which may include a cathode 103, an anode 120, and an aperture 122. The electron beam tool 204 also includes a beam-limiting aperture 124, a condenser lens 126, a source conversion unit 128, an objective assembly 132, a beam splitter 138, and an electron detector 140. In some embodiments, the source conversion unit 128 may include a micro-deflector array 129 and a beam-limiting plate 130. In one embodiment, the objective assembly 132 may include a modified oscillating decelerated immersion objective (SORIL) including an electrode 132a, a control electrode 132b, a deflector 132c, and an excitation coil 132d. Furthermore, the electron beam tool 204 may include an energy-dispersive X-ray spectrometer (EDS) detector (not shown) to characterize materials on the wafer.

[0052] When the electron beam tool 204 operates, the wafer 150 to be inspected is mounted or placed on a wafer holder 136 supported by a motorized stage 134. A voltage is applied between the anode 120 and the cathode 103, and the cathode 103 emits an electron beam 160. The emitted electron beam passes through a gun aperture 122 and a beam-limiting aperture 124, which determine the size of the electron beam entering a condenser lens 126 located below the beam-limiting aperture 124. The condenser lens 126 can focus the emitted electron beam 160 before it enters the source conversion unit 128. A micro-deflector array 129 can split the emitted electron beam into multiple primary electron beams 160a, 160b, and 160c. The number of primary electron beams is not limited to three, and the micro-deflector array 129 can be configured to split the emitted beam into a greater number of primary electron beams. A beam-limiting plate 130 can set the size of the multiple primary electron beams before they enter the objective assembly 132. Deflector 132c deflects primary electron beams 160a, 160b, and 160c to facilitate beam scanning on the wafer. For example, during the scanning process, deflector 132c can be controlled to simultaneously deflect the primary electron beams 160a, 160b, and 160c to different positions on the top surface of wafer 150 at different time points, thereby providing data for image reconstruction of different portions of wafer 150.

[0053] In objective assembly 132, excitation coil 132d and electrode 132a generate a magnetic field that begins at one end of electrode 132a and ends at the other end. A portion of wafer 150 scanned by primary electron beam 160 can be immersed in the magnetic field and can become charged, which in turn generates an electric field. This electric field reduces the energy of the primary electron beam 160 impacting the wafer surface before colliding with it. Control electrode 132b, electrically isolated from electrode 132a, controls the electric field on the wafer to prevent wafer micro-bulging and ensure proper beam focusing.

[0054] When primary electron beams 160a, 160b, and 160c are received, backscattered primary and secondary electrons can be emitted from portions of wafer 150. Beam splitter 138 can guide secondary and / or scattered electron beams 170a, 170b, and 170c (including backscattered and secondary electrons) to the sensor surface of electron detector 140. The detected electron beams 170a, 170b, and 170c can form corresponding beam spots 180a, 180b, and 180c on the sensor surface of electron detector 140. Electron detector 140 can generate a signal (e.g., voltage, current, etc.) representing the intensity of the received beam spots and provide this signal to a processing system, such as controller 109. The intensity of the secondary and / or scattered electron beams 170a, 170b, and 170c and the resulting beam spots can vary depending on the external and / or internal structure of wafer 150. Furthermore, as discussed above, primary electron beams 160a, 160b, and 160c can be projected onto different locations on the top surface of wafer 150 to generate secondary and / or scattered electron beams 170a, 170b, and 170c of varying intensities (and the resulting beam spots). Therefore, by mapping the intensity of the beam spots to the positions of wafer 150, the processing system can reconstruct an image reflecting the internal and / or external structure of wafer 150.

[0055] Furthermore, the electron beam tool 104 can be part of a multi-column aperture SEM system. Additionally, the electron beam tool 104 can also be implemented as an electron beam lithography (EBL) system, such as an electron beam direct writing (EBDW) system. This application does not limit the application to any specific system or technical field of the disclosed charged particle emitter. Therefore, this disclosure is applicable to any charged particle system, such as a FIB (Focused Ion Beam) system, an AFM (Atomic Force Microscopy) system, or other electron beam systems (such as SEM electron beam inspection systems).

[0056] Now for reference Figure 4 , Figure 4 An exemplary component of a selectively variable aperture plate 122a consistent with embodiments of this disclosure is shown. The selectively variable aperture plate 122a may be provided in place of or other than the gun aperture 122. Furthermore, the beam confinement aperture 125 and the column aperture 135 may be configured as selectively variable apertures.

[0057] like Figure 4As shown, the selectively variable aperture plate 122a can be a plate containing multiple apertures. For example, the selectively variable aperture plate 122a includes a first aperture aperture 123a, a second aperture aperture 124a, a third aperture aperture 125a, etc. The diameter of the first aperture aperture 123a is configured to allow an electron beam to pass through and can be configured to produce a relatively large spot size for immersion. The selectively variable aperture plate 122a may include multiple further gradually decreasing aperture apertures for immersing smaller areas and / or suitable for performing electron beam inspection. The number of apertures in the aperture plate is customizable.

[0058] Because electrons emitted from an electron beam source can have a uniform angular density, the current passing through the aperture is directly related to the aperture size. When a selectively variable aperture plate is placed between the electron beam source and the irradiated region, the aperture plate can be configured to use four different aperture sizes to allow electron currents of, for example, 150 nA, 300 nA, 600 nA, and 1200 nA to pass through. The current level specified by the aperture determines the incident current level on the sample. When multiple apertures are arranged in series along the optical axis, the current level can be adjusted sequentially so that each aperture has an influence on the final current incident on the sample.

[0059] In some embodiments, the diameter of the first aperture 123a can be in the range of, for example, 100-200 μm. The aperture plate 122a may be provided with another aperture, for example, 60 μm in diameter, for inspection mode. In inspection mode, it is advantageous to focus the electron beam to a single point. For example, the point-focused probe spot can be on the order of 1 nm. A narrow focused probe spot is advantageous for achieving high imaging resolution.

[0060] In an electron beam tool, a selectively variable aperture plate 122a may be positioned between the electron emitter and the wafer. In some embodiments, the selectively variable aperture plate 122a may be positioned between the electron emitter and the condenser lens of the electron beam tool.

[0061] The material of the selective variable aperture plate 122a is or may include a non-magnetic conductive plate, such as platinum, gold, molybdenum, copper, tantalum, platinum-iridium (95:5), graphite or one or more other materials.

[0062] In another embodiment, the adjustable aperture can be set to an iris-type aperture. The iris-type aperture can be controlled by a motor to achieve precise beam control.

[0063] In the operation of an exemplary charged particle inspection system, pre-charging is performed on the wafer prior to inspection, such as by using an EBI system. In some embodiments, the EBI system 100 can operate in a defocus mode configured to pre-charge the wafer to be inspected. The EBI system 100 can also operate in an imaging mode configured to inspect by electron beam imaging. In both the defocus and imaging modes, the electron emitter of the electron beam tool generates an electron beam.

[0064] like Figure 5 As shown, in defocus mode, the aperture 122 of the electron beam tool 204A operating in defocus mode is configured to allow the electron beam generated by the electron emitter to pass through the aperture 122. For example, in defocus mode, the electron beam tool is configured to generate a defocused electron beam 165 incident on the wafer 150. The defocused electron beam 165 can be adapted to irradiate a relatively large area on the wafer to be inspected. Additional apertures such as the beam-limiting aperture 125 and the pillar aperture 135 can be provided to allow the defocused electron beam to pass through unobstructed. The defocused electron beam 165 can be set by the apertures according to the current level, such that the current of the electron beam is set to a first current level. The current level can be uniformly set such that all apertures 122, beam-limiting aperture 125, and pillar aperture 135 affect the current level of the beam passing through to the wafer. Alternatively, the beam current level can be determined substantially by the aperture 122, while other apertures are set large enough that they do not substantially affect the beam current. The defocused electron beam 165 can pass through the focusing optics of an electron beam tool, such as... Figure 5 The condenser lens 126 and objective lens 132 are schematically shown. However, by means of electro-optics, the defocused electron beam 165 is not focused on a fine point on the surface of the wafer 150. Compared to the probe spot configured for electron beam inspection, the defocused electron beam 165 is relatively defocused, thus giving the defocused electron beam a wide spot size. In some embodiments, the defocused electron beam 165 may be scanned across an area of ​​the wafer 150 for pre-charging. In some embodiments, the defocused electron beam 165 does not scan across the wafer but instead radiates a smaller area.

[0065] In imaging modes, such as Figure 6 As shown, the focusing optics of the electron beam tool 204B, operating in imaging mode, are controlled to focus the electron beam onto a fine point for imaging inspection. For example, in imaging mode, the electron beam tool is configured to generate an inspection electron beam 166 incident on wafer 150. The inspection electron beam is then used for imaging by scanning the beam in a pattern (e.g., a grating pattern) over wafer 150. The inspection electron beam 166 can be set to a second current level.

[0066] The first current level can be greater than or equal to the second current level. For example, pre-charging typically requires a high current level. Since the current level used for testing is usually smaller, the second current level can be less than the first current level. However, the first current level does not necessarily have to be greater than the second current level, for example, in cases where a high current test is used.

[0067] When the second current level is configured to be lower than the first current level, the current level of the inspection electron beam in imaging mode can be set by the aperture of the electron beam tool. For example, the gun aperture 122 can be configured to allow a relatively small current of the electron beam to pass through. When the selectively variable aperture plate 122a is used as the gun aperture 122, an aperture smaller than that used for the defocusing electron beam can be used to allow the inspection beam to be incident on the wafer. In some embodiments, the selectively variable aperture plate 122a is controlled by a motor configured to adjust the X and Y positions of the selectively variable aperture plate 122a such that one of the plurality of apertures (123a, 124a, 125a, 126a, 127a, 128a) is aligned with the optical axis of the electron emitter. The motor can be controlled by a command signal from the controller 109.

[0068] The controller 109 controls the electron beam tool to switch between defocus mode and imaging mode. In defocus mode, the controller 109 controls the motor configured to move the selective variable aperture plate 122a, such that the defocused electron beam is set to a first current level. In imaging mode, the controller 109 controls the motor of the selective variable aperture plate 122a, such that the inspection electron beam is set to a second current level.

[0069] Furthermore, the controller 109 can also control the electro-optical elements to defocus the electron beam in defocus mode. For example, the condenser lens and objective lens of the electro-optical elements can be controlled so that the focal point of the electron beam is not aligned with the wafer surface. The electro-optical elements can adjust the electron beam so that its focal point extends beyond the plane of the wafer in the optical axis direction, thereby increasing the spot size. In imaging mode, the controller 109 can control the electro-optical elements so that the inspection electron beam is relatively more focused than the defocused electron beam incident on the wafer. Specifically, the controller 109 can control the electro-optical elements so that the focal point of the inspection electron beam is aligned with the wafer surface. The controller 109 can also control the electron beam tool by specifying the defocused electron beam to have a specific spot size. The spot size of the defocused electron beam can be larger than the probe spot of the inspection electron beam. Furthermore, the spot of the defocused electron beam can be more dispersed than the probe spot of the inspection electron beam.

[0070] Figure 7An exemplary charged particle beam tool 304A operating in a first mode, consistent with embodiments of the present disclosure, is shown. For clarity, some components have been omitted. The charged particle beam tool 304A includes a charged particle source comprising a cathode 303 and an anode 320. The first mode may include an immersion mode. In the immersion mode, a first aperture 323 is aligned with the optical axis 302 of the charged particle source, sized such that a beam of a first current level is allowed to pass through the first aperture 323a. The first current level may be relatively large, for example, 1000 nA.

[0071] The charged particle beam tool also includes a condenser lens 326, a cylindrical aperture 335, and an objective lens 332. In the charged particle beam tool 304A operating in the first mode, the condenser lens 326 is controlled to focus a 1000 nA beam at the center of the cylindrical aperture 335. The 1000 nA beam can be focused such that essentially all charged particles passing through the first aperture 323a pass through the cylindrical aperture 335. Therefore, the immersion beam current incident on the sample located below the charged particle source can be substantially the same as the first current level. Immersion mode can be achieved by focusing the beam at the center of the cylindrical aperture 335, so that the cylindrical aperture 335 does not restrict the beam current. Since the focused beam is much smaller than the diameter of the cylindrical aperture 335, essentially all the beam current will pass through the aperture and can reach the sample as an immersion current.

[0072] Once the sample is reached, the defocusing beam can be extended to illuminate the area containing the sample, which is 380°.

[0073] Immersion modes may include primary beam immersion of a sample placed below a charged particle source. In primary beam immersion, objective lens 332 may be controlled to focus the beam to a desired level. For example, objective lens 332 may be controlled to produce a primary beam immersion spot 381 with a desired size. The spot size may be adjusted within a range including region 380. Thus, the beam can be controlled to a desired focused level.

[0074] Objective lens 332 can be operated with a wide range of defocus beam shapes / sizes available for use in immersion mode. The size of immersion spot 381 can be adjusted upwards to the size of region 380 (which can, for example, be in the sub-millimeter range, such as around 0.5 mm) and downwards to almost the size of the focused spot (e.g., it can be a few nanometers). The range of spot sizes in immersion mode can include any defocus spot, and in some exemplary embodiments can include a range from 0.1 μm to 500 μm.

[0075] Figure 8An exemplary charged particle beam tool 304B operating in a second mode, consistent with embodiments of this disclosure, is shown. The second mode may include an imaging mode. In the imaging mode, a second aperture 324a is aligned with the optical axis 302 of the charged particle source, allowing a beam of a second current level to pass through the second aperture 324a. The second current level may be relatively small, for example, 20 nA.

[0076] In the charged particle beam tool 304B operating in the second mode, a condenser lens 326 is controlled to focus a 20 nA beam for further precise control. Focusing can occur in conjunction with adjusting the cylindrical aperture 335, or independently of the cylindrical aperture 335. For example, a beam with more or fewer charged particles can be passed through the cylindrical aperture 335, allowing the examination beam to reach the sample at a specific current level (such as 5 nA or 6.5 nA) with precise control. The objective lens 332 is controlled to focus the examination beam to the imaging spot size. Once it reaches the sample, the focused beam can converge at a point on the sample surface, thus forming a probe spot 382. The size of the probe spot 382 can be in the range of a few nanometers or smaller.

[0077] In some embodiments, the immersion electron beam may be configured to form a spot size that substantially surrounds the FOV of the charged particle beam tool.

[0078] When in the first mode, the controller 109 can control the immersion dose. For example, the controller 109 can irradiate the wafer for a predetermined period of time in the first mode.

[0079] In some embodiments, the immersion process can be performed in a continuous movement mode, wherein when immersion is initiated, the wafer is carried by a motorized stage 134 moving at a controlled speed along the X and Y directions. The movement speed can be optimized according to the required immersion dose and timing. In continuous movement mode, a region of the wafer is scanned at least once before imaging scanning to positively or negatively charge the sample according to the secondary electron emission efficiency. When operating in continuous movement mode, the switching time between immersion and imaging is relatively short because the same beam can be used for both immersion and imaging simultaneously. Furthermore, the pre-charge region can be precisely controlled. In some embodiments, a small beam current of the primary electron beam used for imaging may be sufficient for pre-scanning to balance the state of surface charging and / or detect voltage contrast defects with low leakage rates.

[0080] Immersion processing can also be performed in a "Leap and Immersion" mode, where the immersion beam is activated for a period of time at a desired dose, while the motorized stage 134 carries the wafer and stops at a selected location. Immersion processing in the "Leap and Immersion" mode can be advantageous when certain electrical defects with high leakage rates, such as thin voids in copper interconnects, are detected, as these defects require a large amount of electrons to accumulate charge before they can be detected.

[0081] Figure 9 An exemplary charged particle beam tool 304C operating in a hybrid mode, consistent with embodiments of this disclosure, is shown. In hybrid mode, the charged particle beam can combine the functions of immersion and imaging modes. When the charged particle beam tool is in hybrid mode, a first aperture 323a is selected for alignment with the optical axis 302 of the charged particle source. For example, the first aperture 323a may have a size configured to allow a beam of 1000 nA to pass through. Simultaneously, a column aperture with a size suitable for imaging is selected. The column aperture may be a selectively variable aperture. The size of the column aperture 335 may be smaller than the size of the first aperture 323a. For example, the size of the column aperture 335 may be configured to allow a beam of 5 nA to pass through.

[0082] In hybrid mode, the condenser lens 326 can be controlled to generate a beam suitable for immersion and imaging. The control of the condenser lens 326 can be performed independently of adjusting the beam aperture. For example, as... Figure 9 As shown, a condenser lens 326 can be controlled to generate an intermediate beam 350. The intermediate beam 350 is not focused to the center of the cylindrical aperture 335. Therefore, by using a cylindrical aperture of appropriate size to limit the beam, further control of the beam current can be achieved. The intermediate beam 350 can be appropriately shaped as it passes through the cylindrical aperture 335 and the objective lens 332, such that the beam is focused to a point on the sample surface and becomes suitable for imaging. Furthermore, the condenser lens 326 can be controlled to focus a 1000 nA beam passing through the first gun aperture 323a to the center of the cylindrical aperture 335. The 1000 nA beam can be focused such that substantially all charged particles passing through the first gun aperture 323a pass through the cylindrical aperture 335. Therefore, in a hybrid mode, an immersion beam can also be generated, where the current incident on the sample located below the charged particle source is substantially the same as the first current level. Once it reaches the sample, the defocused beam can extend to illuminate the region of the sample containing region 380 and can be further focused by the objective lens 332 to form a primary beam immersion spot 381.

[0083] Operating in hybrid mode further increases switching speed. Since electromagnetic lenses, such as condenser lens 326, can be controlled by electrical input signals, the time required to adjust lens conditions and thus change the beam profile passing through the lens is very short. On the other hand, the aperture is changed by physically moving an aperture plate to align individual aperture holes with the optical axis of the beam. In some embodiments, for example, the condenser lens can be adjusted at ten times the speed of aperture adjustment.

[0084] In some embodiments, operating in a hybrid mode can affect image quality. For example, when a large current beam passes through the gun aperture, a portion of the beam may be incident on the top of the pillar aperture. This can slightly affect the optical performance of the probe beam. For instance, when using a very large current (such as 100 times the current required for imaging), the optical performance may be sufficient for imaging to inspect for defects in the wafer.

[0085] In some embodiments, a relatively large orifice is used, which allows a beam with a current level typically higher than that used for imaging or pre-scanning to pass through. Furthermore, the charged particle beam tool may include a charged particle source with a booster. The booster can be used to increase the beam current of the tool's primary beam source to its highest level, allowing the charged particle source to operate like an immersion gun.

[0086] In an exemplary method consistent with embodiments of this disclosure, a charged particle beam system is used to inspect a sample. The method includes emitting a charged particle beam incident on the sample at a first current level, while the beam defocuses on the surface of the sample. This emission step may be an immersion process. For example, the emission step may include operating the EBI system 100 in a first mode configured to perform immersion to precharge the wafer to be inspected.

[0087] Figure 10 This is a flowchart illustrating an exemplary method consistent with embodiments of this disclosure. (As shown) Figure 10 As shown, the method for inspecting the wafer begins with sample loading step S110. Step S110 may include opening the loading port, inserting the wafer, closing the loading port, sealing the column of the charged particle beam device, and evacuating the vacuum.

[0088] Next, in step S120 of configuring conditions, initial conditions for performing the analysis can be set. For example, the operator can specify the desired voltage, aperture, charged particle beam current level, and focusing settings. In some embodiments, the conditions can be set automatically.

[0089] Next, in step S130, the X and Y positions, tilt, and angular orientation of the wafer can be finely adjusted. For example, the sample stage can be moved to align the desired inspection area on the wafer with the FOV of the charged particle beam device.

[0090] Next, in step S140, wafer immersion may be performed. The immersion process may include emitting a beam of charged particles incident on the wafer at a first current level, while the beam is defocused on the wafer surface. For example, as discussed herein, the immersion process may be performed in a first mode.

[0091] Next, in step S150 of the mode switching process, the conditions of the charged particle beam device can be modified. For example, the voltage, aperture, charged particle beam current level, and focusing can be adjusted. However, it is not necessary to open the sample loading chamber, purge the vacuum, or reset the voltage level before proceeding to the next step.

[0092] In step S160, the sample stage may be further adjusted if necessary.

[0093] In step S170, wafer inspection may be performed. The inspection process may include emitting a beam of charged particles incident on the wafer at a second current level, with the beam focused on the wafer surface. During inspection, the charged particle beam may scan across the wafer surface to generate an image based on detected secondary and / or backscattered charged particles. For example, as discussed herein, the inspection process may be performed in a second mode.

[0094] Next, in verification step S180, the presence of defects can be confirmed. The location of the detected defects can be stored using an address. Additional details of the detected defects, such as type, severity, and an image of the affected area, can also be recorded. Furthermore, the area analyzed in inspection step S170 can be registered as defect-free. Afterward, additional steps can be performed to inspect other areas of the wafer.

[0095] After verifying the regions, the method can proceed to step S190, which involves switching modes, in preparation for repeating steps S140-S180. The method can terminate at the user's command or when all desired regions have been checked.

[0096] As described above, the step of emitting a charged particle beam may include operating the EBI system 100 in a first mode and a second mode, in the first mode controlling the EBI system 100 to defocus its electron beam onto the surface of the wafer 150, and in the second mode controlling the EBI system 100 to focus its electron beam onto a fine point for imaging inspection.

[0097] The exemplary method may also include adjusting the adjustable aperture such that the second current level is less than the first current level. The aperture can be adjusted manually or via a machine through a controller of the charged particle beam system.

[0098] The exemplary method may also include switching from a first mode to a second mode, and vice versa. In some embodiments, the modes may be switched back and forth rapidly. For example, frequent mode switching may be desirable when the structure under inspection can only maintain its charge for a short period of time (which may be due to current leakage, etc.). In this case, the exemplary process may include immersion area (0.2s), mode switching (0.1s), inspection area (0.5s), mode switching again, and moving to a new area, etc.

[0099] When operating in hybrid mode, switching time can be further reduced, thereby improving the performance of rapid switching.

[0100] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various exemplary embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or code portion comprising one or more executable instructions for implementing a specific logical function. It should be understood that in some alternative implementations, the functions indicated in a block may not occur in the order shown in the figures. For example, depending on the function involved, two blocks shown consecutively may execute substantially concurrently, or the two blocks may sometimes execute in reverse order. It should also be understood that each block of a flowchart or block diagram, and combinations thereof, may be implemented by a system based on dedicated hardware that performs a specific function or action, or by a combination of dedicated hardware and computer instructions.

[0101] Possible implementations of the system, method, and computer program product may be stored in internal and / or external data storage. Internal / external storage may be volatile or non-volatile, magnetic, semiconductor, magnetic tape, optical, removable, non-removable, or other types of storage devices or tangible and / or non-transitory computer-readable media. Common forms of non-transitory media include floppy disks, flexible disks, hard disks, solid-state drives, magnetic tape or any other magnetic data storage media, CD-ROMs, any other optical data storage media, any physical media with a perforated pattern, RAM, PROMs and EPROMs, FLASH-EPROMs or any other flash memory, NVRAMs, caches, registers, any other memory chips or cartridges, and their network versions.

[0102] The exemplary embodiments disclosed herein offer specific advantages over conventional immersion gun immersion processes, including the following benefits. For example, it allows for rapid switching from immersion mode to imaging / inspection mode and vice versa. In typical processes using discrete immersion guns, switching to imaging mode can take several minutes. However, in the exemplary embodiments, if the switching time is not less than one second, the switching time can be reduced to a few seconds. Therefore, machine time savings of one to two orders of magnitude can be achieved.

[0103] One advantage of shortening the switchover time is reduced waiting time (the time before inspection begins after immersion). By reducing the amount of leakage charge due to waiting time, inspection sensitivity can be improved. Since certain types of applications are sensitive to waiting / delay times, and the charging conditions generated by electron beam immersion do not persist long before release (leakage), significant switchover time savings help cover more available applications. Furthermore, time savings contribute to increased throughput.

[0104] Compared to conventional immersion guns, the primary beam source of charged particle beam systems (such as SEM columns) possesses more sophisticated local electron optics capabilities and controllability. This makes it advantageous to utilize these capabilities to generate the desired beam current density, dose, field potential, etc., within precisely controlled levels. For example, a variety of energy level settings can be used. In some embodiments, primary beam sources for immersion and imaging are operable in the range of 100 eV–3000 eV. Within this range, energy levels such as 199 eV or 1777 eV can be precisely selected. Values ​​can be selected to individually optimize the desired process, such as immersion or imaging.

[0105] The use of multiple apertures allows for precise control of the target current that will pass through the aperture and advance to the sample. The target current can be controlled depending on the application and desired processing, such as immersion or inspection. In some embodiments, the same aperture used for immersion can be used to perform the inspection function. In some embodiments, the same aperture used for immersion and imaging may be the smallest aperture available in an electron beam inspection tool.

[0106] In addition, in some cases, the first and second modes can share a single aperture to first meet the immersion current requirements, and then reduce the beam current to a level suitable for inspection by combining the use of condenser lenses, objectives and column apertures.

[0107] Neutralization is one application of pre-charge control. In some embodiments, immersion is performed to pre-set the charge on the wafer surface to a specific level before electron beam inspection. In some embodiments, the surface charge of the wafer is neutralized to eliminate the effects of certain prior operations that may have left unwanted charges on the wafer. The operating parameters of the electron beam source can be flexibly selected depending on various immersion conditions.

[0108] According to exemplary embodiments, immersion efficiency can be improved. For example, conventional immersion guns can emit higher currents, such as hundreds of microamps, but their large beam spot size (e.g., exceeding 10 mm) prevents them from immersing smaller areas without over-immersing unnecessary areas. With electron beam inspection machines, areas 10-100 times larger than the region of interest may be unnecessarily immersed due to excessively large beam spots, inaccurate positioning, or non-uniform beam density. According to some exemplary embodiments, immersion methods using a primary beam source from an electron beam inspection tool can precisely limit immersion to the area to be inspected. Therefore, increased accuracy can save time in inspection applications using partial wafer or small-area immersion.

[0109] Furthermore, cost savings can be achieved compared to conventional immersion guns with dedicated controllers or power supplies. For example, exemplary embodiments can eliminate the need for redundant systems, such as separate controllers and power supplies for dedicated immersion guns.

[0110] In an exemplary embodiment, charged particle beam sources configured to operate in both modes can share a single controller for both immersion and inspection functions. Therefore, a system with a dual-mode charged particle source can omit unnecessary components, including separate dedicated immersion guns and their associated accessories, such as their controllers.

[0111] The embodiments may be further described using the following terms:

[0112] 1. A charged particle beam system, comprising:

[0113] The charged particle source is configured to emit a beam of charged particles along the optical axis;

[0114] At least one aperture is configured to allow a beam of charged particles to pass through; and

[0115] The controller is configured as follows:

[0116] Control the charged particle beam system to emit a charged particle beam in a first mode, in which the charged particle beam is incident on a sample at a first current level and the charged particle beam incident on the sample is defocused.

[0117] A charged particle beam system is controlled to emit a charged particle beam in a second mode, in which the charged particle beam is incident on a sample at a second current level and the charged particle beam incident on the sample is focused onto the surface of the sample; and

[0118] The charged particle beam system switches between the first mode and the second mode.

[0119] 2. The charged particle beam system according to Clause 1, wherein the controller is further configured as follows:

[0120] In the first mode, a first spot is formed on the surface of the sample; and

[0121] In the second mode, a second spot is formed on the surface of the sample.

[0122] 3. A charged particle beam system according to Article 1, wherein the first current level is greater than or equal to the second current level.

[0123] 4. A charged particle beam system according to clause 1, wherein the first current level is greater than the second current level.

[0124] 5. According to Article 2, the charged particle beam system in which the first spot is more defocused than the second spot.

[0125] 6. The charged particle beam system according to Clause 2, wherein the controller is further configured as follows:

[0126] Forming a first spot with the first spot size, and

[0127] A second spot with a second spot size is formed, wherein the first spot size is larger than the second spot size.

[0128] 7. The charged particle beam system according to Clause 1, wherein the controller is further configured as follows:

[0129] In the first mode, charged particle immersion is performed on the surface of the sample; and

[0130] In the second mode, charged particle beam inspection is performed on the sample.

[0131] 8. The charged particle beam system according to Article 1 further includes:

[0132] An aperture plate having a first aperture and a second aperture formed thereon, wherein the size of the first aperture is larger than the size of the second aperture; and

[0133] The motor is configured to adjust the position of the orifice plate;

[0134] The controller is configured as follows:

[0135] The aperture plate is moved so that the first aperture is aligned with the optical axis in the first mode; and

[0136] Move the aperture plate so that the second aperture is aligned with the optical axis in the second mode.

[0137] 9. A charged particle beam system according to clause 1, wherein the charged particle beam system is a scanning electron microscope and the charged particle beam is an electron beam.

[0138] 10. A method for examining a sample using a charged particle beam system, the method comprising:

[0139] A beam of charged particles is emitted and incident on the sample at a first current level; the beam of charged particles is defocused on the surface of the sample.

[0140] A beam of charged particles is emitted and incident on the sample at a second current level, and the beam of charged particles is focused on the surface of the sample.

[0141] 11. The method according to Article 10 further includes:

[0142] Adjust the adjustable aperture so that the second current level is lower than the first current level.

[0143] 12. The method according to Article 10 further includes:

[0144] Perform charged particle immersion on the surface of the sample; and

[0145] Perform charged particle beam testing on the sample.

[0146] 13. The method according to Article 10 further includes:

[0147] A first spot is formed on the surface of the sample at a first current level; and

[0148] A second spot is formed on the surface of the sample at the second current level.

[0149] 14. According to the method in Article 10, wherein the second current level is less than the first current level.

[0150] 15. According to the method in Article 13, the second spot is smaller than the first spot.

[0151] 16. A non-transitory computer-readable medium storing a set of instructions executable by one or more processors of a charged particle system to cause the charged particle system to perform a method, the method comprising:

[0152] The charged particle emitter is instructed to emit a charged particle beam in a first mode, in which the charged particle beam is incident on the sample at a first current level and the charged particle beam incident on the sample is defocused.

[0153] Instructs the charged particle system to switch between the first and second modes;

[0154] The charged particle emitter is instructed to emit a charged particle beam in a second mode, in which the charged particle beam is incident on the sample at a second current level and the charged particle beam incident on the sample is focused onto the surface of the sample.

[0155] 17. A computer-readable medium pursuant to Article 16, wherein a set of instructions executable by one or more processors of a charged particle system is configured to cause the charged particle system to further perform:

[0156] The electromagnetic lens is instructed to focus the electron beam in a first mode to form a first spot on the surface of the sample; and

[0157] The electromagnetic lens is instructed to focus the electron beam in a second mode to form a second spot on the surface of the sample.

[0158] 18. A computer-readable medium pursuant to Article 16, wherein a set of instructions executable by one or more processors of a charged particle system is configured to cause the charged particle system to further perform:

[0159] The aperture was changed from a first aperture configured to allow a charged particle beam of the first mode to pass through to a second aperture configured to allow a charged particle beam of the second mode to pass through.

[0160] 19. A computer-readable medium pursuant to Article 16, wherein the first current level is greater than or equal to the second current level.

[0161] 20. A computer-readable medium pursuant to Article 16, wherein the first current level is greater than the second current level.

[0162] 21. A computer-readable medium according to Article 17, wherein the first spot is more defocused than the second spot.

[0163] 22. A computer-readable medium pursuant to Article 17, wherein a set of instructions executable by one or more processors of a charged particle system is configured to cause the charged particle system to further perform:

[0164] Forming a first spot with the first spot size, and

[0165] A second spot with a second spot size is formed, wherein the first spot size is larger than the second spot size.

[0166] 23. A computer-readable medium pursuant to Article 16, wherein a set of instructions executable by one or more processors of a charged particle system is configured to cause the charged particle system to further perform:

[0167] In the first mode, the surface of the sample is immersed in charged particles; and

[0168] Charged particle inspection of samples in the second mode.

[0169] 24. A charged particle beam system, comprising:

[0170] The charged particle source is configured to emit a beam of charged particles along the optical axis;

[0171] At least one aperture is configured to allow a beam of charged particles to pass through;

[0172] At least one electromagnetic lens is configured to control the focusing of a beam of charged particles; and

[0173] The controller is configured as follows:

[0174] Control the charged particle beam system to emit charged particle beams in immersion mode;

[0175] Control the charged particle beam system to emit charged particle beams in a scanning mode; and

[0176] Switch between immersion mode and scanning mode for charged particle beam system.

[0177] 25. According to Article 24, a charged particle beam system, wherein...

[0178] In the first mode and the second mode, at least one aperture is set to a first aperture aperture; and

[0179] At least one electromagnetic lens changes the focus of the charged particle beam between immersion mode and scanning mode.

[0180] 26. A charged particle beam system according to Article 24, wherein the charged particle source is the primary beam of a charged particle beam tool.

[0181] It should be understood that the present invention is not limited to the exact structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. Furthermore, the exemplary embodiments described above are not necessarily mutually exclusive, but can be combined with each other. For example, a continuous movement mode can be implemented even by changing the aperture between the first and second modes. Moreover, the aperture may include a circular hole, a slit, or any shape suitable for allowing the beam to pass through.

[0182] The scope of this invention should be limited only by the appended claims.

Claims

1. A charged particle beam system, comprising: The charged particle source is configured to emit a beam of charged particles along the optical axis; An adjustable aperture plate is configured to allow a beam of charged particles to pass through, and the adjustable aperture plate can be changed to provide a selected aperture size; At least one electromagnetic lens is configured to control the focusing of the charged particle beam; as well as The controller is configured as follows: The charged particle beam system is controlled to emit the charged particle beam in an immersion mode, wherein the charged particle beam passes through the adjustable aperture plate with a first aperture size, thereby incident on the sample at a first current level and the charged particle beam incident on the sample is defocused. The charged particle beam system is controlled to emit the charged particle beam in a scanning mode, wherein the charged particle beam passes through the adjustable aperture plate with a second aperture size, thereby incident on the sample at a second current level and being focused onto the surface of the sample; and The charged particle beam system switches between the immersion mode and the scanning mode within a few seconds.

2. The charged particle beam system according to claim 1, wherein... In the immersion mode and the scanning mode, the at least one aperture is set to a first aperture aperture; and The at least one electromagnetic lens changes the focus of the charged particle beam between the immersion mode and the scanning mode.

3. The charged particle beam system according to claim 1, wherein the charged particle source is the primary beam of a charged particle beam tool.

4. The charged particle beam system according to claim 1, wherein: In the immersion mode, the charged particle beam forms a first spot on the surface of the sample; and In the scanning mode, the charged particle beam forms a second spot on the surface of the sample.

5. The charged particle beam system according to claim 1, wherein the first current level is greater than the second current level.

6. The charged particle beam system of claim 4, wherein the first spot is larger than the second spot.

7. The charged particle beam system of claim 4, wherein the first spot is more defocused than the second spot.

8. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a charged particle beam system, cause the charged particle beam system to: A charged particle beam is emitted in immersion mode through an adjustable aperture plate with a first aperture size, such that the charged particle beam is incident on the surface of the sample at a first current level and is defocused on the surface. A charged particle beam, passing through the aperture plate with a second aperture size, is emitted in a scanning mode such that the charged particle beam is incident on the sample at a second current level, and the charged particle beam is focused on the surface; and The charged particle beam system switches between the immersion mode and the scanning mode within a few seconds.

9. The computer-readable medium of claim 8, wherein the instructions, when executed, cause the charged particle beam system to further: Adjust the adjustable aperture so that the second current level is less than the first current level.

10. The computer-readable medium of claim 8, wherein the instructions, when executed, cause the charged particle beam system to further: Perform charged particle immersion on the surface; and The sample was subjected to charged particle beam testing.

11. The computer-readable medium of claim 8, wherein the instructions, when executed, cause the charged particle beam system to further: A first spot is formed on the surface of the sample at the first current level; and A second spot is formed on the surface at the second current level.

12. The computer-readable medium of claim 8, wherein the second current level is less than the first current level.

13. The computer-readable medium of claim 11, wherein the second spot is smaller than the first spot.

14. The computer-readable medium of claim 11, wherein the first spot is more defocused than the second spot.

15. A non-transitory computer-readable medium storing instructions, which, when executed by a processor of a charged particle beam system, causes the charged particle beam system to: A charged particle beam is emitted in immersion mode, wherein the charged particle beam passes through an adjustable aperture plate with a first aperture size and is incident on the surface of a sample with a first current level, and the charged particle beam is defocused on the surface. A charged particle beam is emitted in a scanning mode, wherein the charged particle beam passes through the aperture plate with a second aperture size, is incident on the sample with a second current level, and is focused on the surface; and The charged particle beam system switches between the immersion mode and the scanning mode within a few seconds.

Images