Charged particle beam inspection device and method

Abstract

Charged particle beam inspection systems and charged particle beam conditioning techniques for inspecting specimens (550), and more particularly, charged particle beam non-contact electrical characterization techniques (eg, for defect detection) are disclosed. The charged particle beam device includes a charged particle source (503) configured to emit a primary charged particle beam (505), a first lens (526) configured to manipulate the primary charged particle beam to adjust a probe current of the primary charged particle beam, an objective lens (532) configured to focus the primary charged particle beam substantially to a focal point on the surface of the sample, second lenses (533d, e) configured to generate an electrostatic field that substantially overlaps with the magnetic field generated by the objective lens and to compensate for focus variations caused by changes in the probe current without changing the focusing power of the objective lens, where the changes in the probe current are caused by the first lens, and deflectors (533a-e) configured to deflect the primary charged particle beam to scan a scan line of a field of view of the sample.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. patent application Ser. No. 63 / 434,338, filed Dec. 21, 2022, which is incorporated herein by reference in its entirety.

[0002]

[0002] Embodiments provided herein disclose charged particle beam inspection devices and charged particle beam conditioning techniques, more particularly non-contact electrical characterization techniques using charged particle beam inspection devices that can be used to rapidly vary charged particle beam parameters to determine electrical characteristics of a specimen without direct contact. [Background technology]

[0003]

[0003] In the integrated circuit (IC) manufacturing process, unfinished or completed circuit components are inspected to ensure they are manufactured as designed, are defect-free, and have the desired electrical characteristics. Inspection systems may be employed that utilize charged particle (e.g., electron) beam microscopes, such as scanning electron microscopes (SEMs), or optical microscopes. As the physical size of IC components continues to shrink, the accuracy and yield of IC inspection become increasingly important. In an SEM, a beam of relatively high-energy primary electrons is decelerated and focused to land on the sample with a relatively low landing energy, forming a probe spot on the sample. This focused probe spot of primary electrons generates secondary electrons from the surface. The secondary electrons are detected by an electron detector, producing an SEM image of the sample.

[0004]

[0004] Inspection images, such as SEM images, can be used to identify or classify defects in manufactured ICs. To inspect the electrical properties of small IC device structures, an SEM can apply an electrical signal to a specimen and measure the corresponding response. However, generating an I-V curve for the specimen requires rapid adjustment of the electron beam current and focus. To improve defect detection and electrical characterization, inspection tools and methods that can increase throughput and maintain the structural fidelity of ICs are desired. Summary of the Invention

[0005]

[0005] The embodiments provided herein disclose a charged particle beam system for inspecting a sample, more specifically a charged particle beam system for inspecting a sample that includes an improved rapid focus compensation mechanism.

[0006] Some embodiments provide a charged particle beam device for inspecting a specimen, the device including: a charged particle source configured to emit a primary charged particle beam; a first lens configured to manipulate the primary charged particle beam to adjust a probe current of the primary charged particle beam; an objective lens configured to focus the primary charged particle beam substantially to a focal point on a surface of the specimen; a second lens configured to generate an electrostatic field that substantially overlaps with the magnetic field generated by the objective lens and to compensate for focus variations caused by changes in the probe current without changing the focusing power of the objective lens, where the changes in the probe current are caused by the first lens; and a deflector configured to deflect the primary charged particle beam to scan a scan line of a field of view of the specimen.

[0007]

[0007] In some embodiments, a non-transitory computer-readable medium is provided that stores a set of instructions executable by one or more processors of a charged particle beam device to cause the charged particle beam device to perform a method for inspecting a sample. The method includes using a first lens to steer a primary charged particle beam emitted by a charged particle source to change the current of the primary charged particle beam to a first probe current; using an objective lens to focus the primary charged particle beam at the first probe current substantially to a focal point on a surface of the sample; scanning a first scan line of a field of view of the sample with the primary charged particle beam at the first probe current; after scanning the first scan line, using the first lens to steer the primary charged particle beam to change the current of the primary charged particle beam to a second probe current; using a second lens to compensate for focus variations of the primary charged particle beam at the second probe current without changing a setting of the objective lens; and scanning a second scan line of the field of view with the primary charged particle beam at the second probe current, wherein the scanning of the first line and the scanning of the second line are performed sequentially.

[0008]

[0008] Other advantages of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, in which certain embodiments of the present disclosure are shown by way of illustration and example.

[0009]

[0009] These and other aspects of the present disclosure will become more apparent from the description of the exemplary embodiments read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1]

[0010] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam inspection system consistent with embodiments of the present disclosure. [Figure 2]

[0011] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam tool consistent with embodiments of the present disclosure. [Figure 3]

[0012] 1 is an example of a graph showing secondary electron yield versus landing energy of primary electrons. [Figure 4]

[0013] FIG. 1 is a schematic diagram illustrating the voltage contrast response of a sample when an electron beam strikes the sample. [Figure 5]

[0014] FIG. 1 is a schematic diagram illustrating an exemplary charged particle beam device for inspecting electrical characteristics of a specimen, consistent with embodiments of the present disclosure. [Figure 6]

[0015] FIG. 1 is a schematic diagram illustrating an exemplary scan line of a focused electron beam across a sample surface applied by a charged particle beam device consistent with embodiments of the present disclosure. [Figure 7]

[0016] 1 is a schematic diagram of a top portion of an exemplary charged particle beam device including a stigmator consistent with embodiments of the present disclosure. [Figure 8]

[0017] 1 is a flowchart depicting an exemplary process for compensating charged particle beam focus consistent with embodiments of the present disclosure. [Figure 9]

[0018] 1 is a flowchart depicting an exemplary process for inspecting electrical characteristics of a specimen without direct contact, consistent with embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0019] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which, unless otherwise stated, like numbers in different drawings represent the same or similar elements. The implementations described in the following description of exemplary embodiments do not represent all implementations consistent with the present invention. Instead, they are merely examples of apparatus and methods consistent with aspects related to the present invention as recited in the appended claims.

[0012]

[0020] Increasing the computing power of electronic devices while shrinking their physical size can be achieved by dramatically increasing the packing density of circuit components such as transistors, capacitors, and diodes on IC chips. For example, a smartphone IC chip can be about the size of a thumbnail yet contain over 2 billion transistors, each less than 1 / 1000 the size of a human hair. It is not surprising, therefore, that semiconductor IC manufacturing is a complex and time-consuming process involving hundreds of individual steps. An error in even one step can dramatically affect the functionality of the final product. Even a single "killer defect" can cause device failure. The goal of a manufacturing process is to improve the overall yield of the process. For example, to achieve a 75% yield for a 50-step process, each individual step must have a yield greater than 99.4%; if each individual step has a 95% yield, the overall process yield drops to 7%.

[0013]

[0021] In IC chip manufacturing facilities, high process yields are desirable, but maintaining high wafer throughput, defined as the number of wafers processed per hour, is also essential. The presence of defects can impact high process yields and high wafer throughput, especially if operator intervention is required to examine the defects. Therefore, the ability of inspection tools (such as SEMs) to detect and identify micro- and nano-sized defects at high throughput is essential to maintaining high yields and low costs.

[0014]

[0022] An SEM scans a focused electron beam across the surface of a sample. The electrons interact with the sample, generating secondary electrons. By scanning the electron beam across the sample and capturing the secondary electrons with a detector, an SEM generates an image of the sample that shows the internal device structure underlying the area of ​​the sample under inspection. Traditional SEM inspection tools acquire a single image of an area of ​​the sample and compare the acquired image to a reference image that represents the corresponding device structure without defects. Differences detected from the image comparison can indicate defects in the sample.

[0015]

[0023] Nanoprobe techniques can be used with SEMs to obtain electrical characteristics (e.g., resistance, capacitance, etc.) of a sample. For example, an SEM can apply an electrical signal via an electron beam impinging on the sample and measure the corresponding electrical response, thus determining the sample's electrical characteristics or properties. To holistically analyze a sample's electrical properties, the current of the electron beam in the SEM can be adjusted to induce different electrical responses in the sample, thereby generating a current-voltage relationship (e.g., an I-V curve). However, conventional SEM systems cannot support rapid adjustment of the electron beam current because the adjustment process is slow. Therefore, users cannot, for example, rapidly scan a node multiple times in rapid succession with different probe currents for each scan, undesirably limiting the ability to extract specific I / V information.

[0016]

[0024] Embodiments of the present disclosure may provide an electron beam inspection apparatus that scans a specimen multiple times in rapid succession using different electron beam parameters, thereby enabling the determination of the specimen's electrical characteristics or properties (e.g., IV curves) without direct contact. Embodiments of the present disclosure may provide an electrostatic lens that can quickly compensate for the focus of the electron beam when the electron beam current is adjusted. Because the objective lens can be kept constant during this focus adjustment, less energy and time is required to focus the electron beam on the specimen and thereby measure the specimen's electrical characteristics or properties. Thus, the disclosed electron beam inspection apparatus supports rapid electron beam parameter adjustment and can determine specimen IV curves that would not be obtainable without such rapid electron beam parameter adjustment. For ease of explanation and without ambiguity, electrons are used as an example in the description herein. However, it should be noted that any charged particle, not limited to electrons, may be used in any embodiment of the present disclosure.

[0017]

[0025] Relative dimensions of components in the drawings may be exaggerated for clarity. Within the following description of the drawings, identical or similar reference numbers refer to identical or similar components or entities, and only differences with respect to individual embodiments are described. As used herein, unless otherwise stated, the term "or" encompasses all possible combinations unless infeasible. For example, if it is stated that a database may include A or B, the database may include A or B, or A and B, unless otherwise stated or infeasible. As a second example, if it is stated that a database may include A, B, or C, the database may include A, or B, or C, or A and B, or A and C, or B and C, or A, B, and C, unless otherwise stated or infeasible.

[0018]

[0026] Reference is now made to Figure 1, which is a schematic diagram illustrating an exemplary charged particle beam inspection system 100 consistent with embodiments of the present disclosure. As shown in Figure 1, the charged particle beam inspection system 100 includes a main chamber 101, a load lock chamber 102, an electron beam tool 104, and a front-end equipment module (EFEM) 106. The electron beam tool 104 is located within the main chamber 101. While the description and drawings are directed to an electron beam, it should be understood that the embodiments are not intended to limit the present disclosure to any particular charged particle.

[0019]

[0027] The EFEM 106 includes a first load port 106a and a second load port 106b. The EFEM 106 may include additional load ports. The first load port 106a and the second load port 106b may, for example, receive specimens (e.g., semiconductor wafers or wafers made of other materials) or specimen front-opening integrated pods (FOUPs) containing specimens to be inspected (wafers and specimens hereinafter collectively referred to as "specimens"). One or more robotic arms (not shown) within the EFEM 106 transport the specimens to the load lock chamber 102.

[0020]

[0028] The load lock chamber 102 may be connected to a load lock vacuum pumping system (not shown) that removes gas molecules within the load lock chamber 102 to reach a first pressure below atmospheric pressure. After the first pressure is reached, one or more robotic arms (not shown) transfer the specimen 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 within the main chamber 101 to reach a second pressure below the first pressure. After the second pressure is reached, the specimen is subjected to inspection by an electron beam tool 104. In some embodiments, the electron beam tool 104 may include a single-beam electron inspection tool.

[0021]

[0029] The 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 charged particle beam inspection system 100. While the controller 109 is shown in FIG. 1 as being external to the structure including the main chamber 101, the load lock chamber 102, and the EFEM 106, it should be understood that the controller 109 may be part of the structure. While the present disclosure provides an example of a main chamber 101 housing an electron beam inspection tool, it should be noted that aspects of the present disclosure, in their broadest sense, are not limited to chambers housing electron beam inspection tools. Rather, it should be understood that the principles described above may also be applied to other tools operating under a second pressure.

[0022]

[0030] Reference is now made to Figure 2, which is a schematic diagram illustrating an exemplary imaging system 200 including an electron beam tool 104 and an image processing system 290 consistent with embodiments of the present disclosure. As shown in Figure 2, the electron beam tool 104 may include a motorized stage 234 for supporting a sample 250 to be inspected. The electron beam tool 104 may further include an objective lens 232, an electron detector 244 (including an electron sensor surface), a condenser lens 226, a Coulomb aperture 224, a Gunn aperture 222, an anode 220, and a cathode 203, one or more of which may be aligned with an optical axis 201 of the electron beam tool 104. In some embodiments, the detector 244 may be positioned off the optical axis 201.

[0023]

[0031] The objective lens 232 may include a modified swing objective retardation immersion lens (SORIL), which may include an objective lens body 232 a and an objective excitation coil 232 b. Within the objective lens 232 there may be a deflector or set of deflectors 233. The electron beam tool 104 may additionally include an energy dispersive X-ray spectrometer (EDS) detector (not shown) for characterizing materials on the sample.

[0024]

[0032] The primary electron beam 204 may be emitted from the cathode 203 by applying a voltage between the anode 220 and the cathode 203. The primary electron beam 204 may pass through a gun aperture 222 and a coulomb aperture 224, both of which may determine the current of the primary electron beam 204 incident on a condenser lens 226 located below the coulomb aperture 224. The condenser lens 226 may focus the primary electron beam 204 before it incidents on a current-limiting aperture 235 and set the current of the electron beam before it incidents on the objective lens 232. The set current of the primary electron beam 204 incident on the objective lens 232 may be referred to as the probe current.

[0025]

[0033] The objective lens 232 can focus the primary electron beam 204 onto the sample 250 for inspection and can form a probe spot 240 on the surface of the sample 250. The deflector 233 can deflect the primary electron beam 204 to scan the probe spot 240 across the entire surface of the sample 250. For example, in the scanning process, the deflector 233 can be controlled to sequentially deflect the primary electron beam 204 to different positions on the top surface of the sample 250 at different times to provide data for image reconstruction of different portions of the sample 250. Furthermore, the deflector 233 can also be controlled to deflect the primary electron beam 204 to different sides of the sample 250 at specific locations at different times to provide data for stereo image reconstruction of the sample structure at that location.

[0026]

[0034] When an electric signal is applied to the objective excitation coil 232b, an axially symmetric (i.e., symmetric about the optical axis 201) magnetic field can be generated in the sample surface region. A portion of the sample 250 scanned by the primary electron beam 204 can be immersed in the magnetic field. Different voltages can be applied to the sample 250 to generate an axially symmetric retarding electrostatic field near the sample surface. This electrostatic field can reduce the energy of the impinging primary electron beam 204 near the surface of the sample before the electrons of the primary electron beam 204 collide with the sample 250.

[0027]

[0035] Upon receiving the primary electron beam 204, secondary electrons 205 may be emitted from that portion of the sample 250. Although not shown in FIG. 2 , it should be understood that the primary electron beam 204 striking the sample 250 may also generate backscattered electrons or Auger electrons. The secondary electrons 205 may be received by a sensor surface of the electron detector 244. In some embodiments, the electron detector 244 may generate a signal (e.g., voltage, current, etc.) representing the intensity of the emitted secondary electrons 205 and provide the signal to an image processing system 290 in communication with the electron detector 244. The intensity of the emitted secondary electrons 205 may vary depending on the external or internal structure of the sample 250 and may therefore indicate whether the sample 250 contains defects. Furthermore, as described above, the primary electron beam 204 may be projected at different locations on the top surface of the sample 250 or at different sides of the sample 250 at specific locations to generate secondary electrons 205 of different intensities. Thus, by mapping the intensity of the emitted secondary electrons 205 to areas of the sample 250 , the image processing system 290 can reconstruct an image reflecting features of the internal or external structure of the sample 250 .

[0028]

[0036] The imaging system 200 may also include an image processing system 290, which includes an image acquisition unit 292, storage 294, and the controller 109. The image acquisition unit 292 may include one or more processors. For example, the image acquisition unit 292 may include a computer, a server, a mainframe host, a terminal, a personal computer, any type of mobile computing device, and the like, or a combination thereof. The image acquisition unit 292 may be communicatively coupled to the detector 244 of the electron beam tool 104 through a medium such as electrical conductors, fiber optic cables, portable storage media, IR, Bluetooth, the Internet, a wireless network, radio, or a combination thereof. The image acquisition unit 292 may receive signals from the detector 244 and construct an image. Thus, the image acquisition unit 292 may acquire an image of the sample 250. The image acquisition unit 292 may also perform various post-processing functions, such as generating contours, overlaying indicators on the acquired image, and the like. The image acquisition unit 292 may be configured to adjust the brightness and contrast of the acquired image, etc. The storage 294 may be a storage medium such as a hard disk, a flash drive, cloud storage, random access memory (RAM), or other type of computer-readable memory. The storage 294 may be coupled to the image acquisition unit 292 and may be used to store scanned raw image data as original images and post-processed images. The image acquisition unit 292 and the storage 294 may be connected to the controller 109. The image acquisition unit 292, the storage 294, and the controller 109 may be integrated together as one control unit.

[0029]

[0037] The image acquisition unit 292 may acquire one or more images of the sample based on the imaging signal received from the detector 244. The imaging signal may correspond to a scanning motion for performing charged particle imaging. The acquired image may be a single image including multiple imaged areas. This single image may be stored in the storage 294. This single image may be an original image that may be divided into multiple regions. Each of the regions may include an imaged area that includes a feature of the sample 250. The acquired image may include multiple images of a single imaged area of ​​the sample 250 sampled multiple times over a time series. The multiple images may be stored in the storage 294. The image processing system 290 may be configured to perform image processing steps using multiple images of the same location of the sample 250.

[0030]

[0038] The image processing system 290 may include measurement circuitry (e.g., an analog-to-digital converter) to acquire the distribution of detected secondary electrons. The electron distribution data collected during the detection time window can be used in combination with corresponding scan path data of the primary electron beam 204 incident on the sample surface to reconstruct an image of the sample structure under inspection. The reconstructed image can be used to reveal various features of the internal or external structure of the sample 250, thereby revealing any defects that may be present in the sample.

[0031]

[0039] Reference is now made to FIG. 3, which is an exemplary graph illustrating the yield of emitted secondary electrons versus the landing energy of the primary electrons. This graph shows the relationship between the landing energy or current of a primary electron beam (such as primary electron beam 204 in FIG. 2) and the yield of emitted secondary electrons (such as secondary electrons 205 in FIG. 2). The yield of emitted secondary electrons indicates how many secondary electrons are emitted in response to primary electrons striking the sample surface. For example, a yield greater than 1.0 indicates that more secondary electrons may be emitted from the surface of the sample compared to the number of primary electrons striking the sample. Similarly, a yield less than 1.0 indicates that fewer secondary electrons may be emitted in response to primary electrons striking the sample.

[0032]

[0040] As shown in the graph in Figure 3, when the landing energy of the primary electrons is in the range of E1 to E2, more secondary electrons may be emitted from the sample surface than the primary electrons that strike the sample surface, resulting in a positive potential, or voltage, on the sample surface. For samples with a more positive surface potential, the detector may receive fewer secondary electrons, resulting in a darker voltage-contrast image.

[0033]

[0041] Reference is now made to FIG. 4, which is a schematic diagram illustrating the voltage contrast response of a sample when a primary electron beam strikes the sample, consistent with embodiments of the present disclosure. When an electron beam tool (such as the electron beam tool 104 of FIG. 2) scans the surface of a sample 450 with electrons from a primary electron beam 404, secondary electrons 405 (and other species, such as backscattered electrons or Auger electrons) may be emitted from the surface. The ratio of the number of emitted secondary electrons 405 to the incident electrons striking the surface of the sample 450 from the primary electron beam 404 determines the yield of emitted secondary electrons, as discussed above. The field of view of the sample 450 may have different microstructures 450_1, 450_2, and 450_3. In the example shown in FIG. 4, microstructure 450_2 is struck by the primary electron beam 404, and secondary electrons 405 are emitted from the sample 450 in response. The secondary electrons 405 may be collected and measured by a detector.

[0034]

[0042] As discussed above with respect to FIG. 3 , the secondary electron emission yield can be controlled by appropriately adjusting the landing energy of the primary electron beam (e.g., primary electron beam 404). For example, by selecting an appropriate landing energy between E1 and E2, the secondary electron emission yield can be greater than 1, which can positively charge the surface of the sample microstructure 450_2 as shown in FIG. 4 . Referring again to FIG. 4 , the positively charged top surface of the sample microstructure 450_2 generates a voltage difference 420 between the top surface of the microstructure 450_2 and a substrate 460, which can be electrically grounded. As a result, a sample current 410 can flow through the microstructure 450_2. As discussed with respect to FIG. 3 , varying the landing energy of the primary electron beam affects the number of emitted secondary electrons. Referring again to FIG. 4 , the probe current of the primary electron beam 404 can be varied while keeping the landing energy of the primary electron beam 404 constant. This can change the secondary electron emission yield and the voltage difference 420. Thus, by controlling the probe current of the primary electron beam 404, the voltage difference 420 and the specimen current 410 can be varied. The specimen current 410 of the microstructure 450_2 can be determined as the difference between the probe current of the primary electron beam 404 and the current of the emitted secondary electrons 405 measured by the detector. Using the signal collected from the detector measuring the emitted secondary electrons 405, an image of the specimen 450 having the microstructure 450_2 can be generated by an image processing system or controller. The voltage contrast of the image can be applied to back-calculate the secondary electron yield and the voltage difference 420.

[0035]

[0043] Sample characteristics of the microstructure 450_2, such as resistance, capacitance, and other electrical properties, can be calculated based on the back-calculated and measured values. For example, a resistance value can be determined by dividing the calculated sample voltage difference 420 by the calculated sample current 410. The calculated resistance value can be compared to a standard resistance value for the sample (e.g., an expected resistance based on the design parameters of the device structure) as a form of defect detection. A significant difference between the calculated resistance value and the standard resistance value for the sample can indicate the presence of a defect in the imaged region of the sample. To analyze the sample's electrical properties in more detail, as shown in FIG. 3, the probe current of the primary electron beam 404 can be varied to produce a yield of emitted secondary electrons greater than one. Referring again to FIG. 4, the probe current of the primary electron beam 404 can be adjusted and the primary electron beam 404 can be re-scanned across the sample 450. This can produce different yields of emitted secondary electrons, thus generating a second set of values ​​for the sample current 410 and the sample voltage difference 420, as described above. This can be repeated multiple times, with each probe current selected to produce a different sample voltage difference each time while maintaining a yield greater than 1. These multiple data points can be used to generate an IV curve representing the electrical characteristics of microstructure 450_2.

[0036]

[0044] Reference is now made to FIG. 5, which is a schematic diagram illustrating an exemplary charged particle beam device for inspecting electrical characteristics of a specimen consistent with embodiments of the present disclosure. The charged particle beam device may include a cathode 503, a Coulomb aperture 524, a condenser lens 526, a current-limiting aperture 535, an objective lens 532, and multiple deflectors 533a-533e. As described above, the cathode 503 emits a primary electron beam 505, which passes through the Coulomb aperture 524 before entering the condenser lens 526. The condenser lens 526 may focus the primary electron beam 505 before it enters the current-limiting aperture 535. The objective lens 532 may then focus the primary electron beam 505 onto the surface of the specimen 550.

[0037]

[0045] In some embodiments, the controller 109 may be communicatively coupled to the condenser lens 526, the current-limiting aperture 535, the electron detector (not shown), and the objective lens excitation coil 532b to provide electrical signals (e.g., current, voltage). In some embodiments, the controller 109 may be communicatively coupled to a deflector (e.g., deflector 533d) to provide electrical signals. In some embodiments, the condenser lens 526 may be used to control the probe current of the primary electron beam 505, as described above in FIGS. 2 and 3, which may determine the landing energy of the primary electrons. The controller 109 may provide electrical signals to the condenser lens 526 to generate a magnetic field 526_a, which may provide a focusing effect (e.g., collimation or focusing) to manipulate the primary electron beam 505. The strength of the electrical signal provided by the controller 109 to the condenser lens 526 determines the strength of the magnetic field 526_a, which affects the strength of the focusing effect on the primary electron beam 505. As shown in FIG. 5 , an electrical signal applied to the condenser lens 526 focuses the primary electron beam 505. As a result, the concentration of electrons in the primary electron beam 505 passes through the current-limiting aperture 535, determining the diameter of the primary electron beam 505 and the corresponding probe current. Dashed line 505_1 serves as an exemplary path that electrons in the primary electron beam 505 follow to pass through the current-limiting aperture 535. The greater the ratio of electrons in the primary electron beam 505 that pass through the current-limiting aperture 535 to those in the primary electron beam 505 that are blocked, the greater the probe current. It should be understood that the current-limiting aperture 535 may be of a fixed width, such that the condenser lens 526 can control the probe current of the primary electron beam 505. It should further be understood that the current-limiting aperture 535 may be adjustable.

[0038]

[0046] The condenser lens 526 can be adjusted to change the probe current of the primary electron beam 505. This change in probe current can cause the primary electron beam 505 to become out of focus when it strikes the surface of the sample 550. Typically, the objective lens 532 must be adjusted to refocus the primary electron beam 505, but because the objective lens 532 is a magnetic component, this can often be a slow adjustment. This can therefore reduce the throughput of sample analysis. In some embodiments, other components of the exemplary charged particle device shown in FIG. 5 can be used to compensate for focus variations that accompany changes in the probe current of the primary electron beam 505 without adjusting the focusing power of the objective lens 532.

[0039]

[0047] For example, if the electrical signal applied to the objective lens excitation coil 532b remains constant and the corresponding magnetic field 532b_a applies a focusing effect of a constant strength to the primary electron beam 505, the objective lens 532 will underfocus or overfocus the primary electron beam 505 on the sample 550 (i.e., the focal point will be below the sample 550 in the case of an underfocused primary electron beam 505, and above the sample 550 in the case of an overfocused primary electron beam 505), even after changing the focusing effect of the condenser lens 526 (e.g., adjusting the focus of the primary electron beam 505) to increase or decrease the probe current of the primary electron beam 505. The dashed-dotted line 505a in FIG. 5 indicates the underfocused situation. In some embodiments, the deflector 533d may be used as an electrostatic lens to compensate for the underfocus or overfocus effect (i.e., focus variation). For example, the controller 109 may apply a DC bias electrical signal to the deflector 533d, which may include multiple electrodes. When a DC bias electric signal is applied to all electrodes, the deflector 533d can function not only as a deflector but also as an electrostatic lens. The deflector 533d can generate a corresponding electrostatic field 533d_a that can provide a focusing effect on the primary electron beam 505 to compensate for the under- or over-focusing effect caused by changes in the probe current. The solid line 505b shows the compensated (refocused) primary electron beam 505. During this process, the magnetic field strength of the magnetic field 532b_a can remain the same compared to a state in which only the magnetic field 532b_a exerts a focusing effect on the primary electron beam 505.

[0040]

[0048] Because the deflector 533d is positioned relatively close to the magnetic field 532b_a, there may be overlap between the distribution of the electrostatic field 533d_a and the distribution of the magnetic field 532b_a, which may minimize the impact on fluctuations in the expansion and resolution of the primary electron beam 505. Because adjusting the settings of a magnetic lens is typically slower than that of an electrostatic lens, using the deflector 533d to compensate for focus instead of changing the magnetic objective lens 532 may minimize the impact on throughput. Because the deflector 533d functions as an electrostatic lens, changing the electrostatic field strength of the electrostatic field 533d_a may be faster than changing the field strength of the magnetic field 532b_a from the objective lens 532 to compensate for focus when adjusting the probe current. In some embodiments, the deflector 533d may have a small inner diameter, and therefore the electrical signal required to compensate for focus is lower than the electrical signal required to adjust the objective lens 532. This may help achieve high-speed focus compensation. In some embodiments, the electrical signal applied to the deflector 533d to compensate for the focus of the primary electron beam 505 does not interfere with the deflection function of the deflector 533d, so that the deflector 533d functions not only as a deflector but also as an electrostatic lens. In some embodiments, the deflector 533d used for focus compensation can be separate from the scanning deflectors, such as the deflectors 533b or 533c, when making local measurements with a small field of view.

[0041]

[0049] While FIG. 5 describes an embodiment using deflector 533d to compensate for overfocus or underfocus effects, it should be understood that other components can be utilized for compensation. For example, in some embodiments, a deflector positioned below the objective lens (e.g., deflector 533e or an objective lens control electrode (not shown)) can be used instead of deflector 533d to compensate for overfocus or underfocus effects. Because deflector 533e is positioned closer to the sample 550 than deflector 533d, the electrical signal applied to deflector 533e to compensate for the focus does not need to be stronger compared to the electrical signal applied to deflector 533d. In some embodiments, both deflectors 533d and 533e can be used to compensate for overfocus or underfocus effects. Using both deflectors 533d and 533e further reduces the required electrical signal and, therefore, can reduce the energy input required to compensate for the focus of the primary electron beam 505 when adjusting the probe current. Additionally, for larger adjustments to the probe current of the primary electron beam 505, a large amount of focus compensation may be required, and therefore both deflectors 533d and 533e may be used.

[0042]

[0050] Additionally, while the condenser lens 526 may be a magnetic lens as described above, it should be understood that other configurations of the condenser lens 526 may be utilized. For example, in some embodiments, the condenser lens 526 may be an electrostatic lens. In embodiments in which the condenser lens 526 may be an electrostatic lens, adjusting the probe current (using the condenser lens 526) and compensating for focus (using the deflectors 533d, 533e, or both) may be a fully electrostatically controlled process that may be faster than using magnetic components. In some embodiments, the condenser lens 526 may be a hybrid magnetic and electrostatic lens used in combination with the deflectors 533d, 533e, or both, as described above. In some embodiments, the magnetic components of the condenser lens may be kept the same while the electrostatic components may be changed to adjust the probe current, increasing the throughput of the probe current adjustment and focus compensation described above.

[0043]

[0051] The focused primary electron beam 505 striking the sample 550 may emit corresponding secondary electrons, which may be collected and measured by a corresponding detector (not shown). An image processing system 590 may then generate an image of the sample 550 based on the intensity of the collected secondary electron signal. If the probe current is selected such that the yield of secondary electrons exceeds unity, a processing system (e.g., image processing system 590) may calculate the corresponding voltage difference and current across the sample 550 and then determine the electrical characteristics of the sample 550 as described above with respect to FIG. 4.

[0044]

[0052] Reference is now made to FIG. 6, which is a schematic diagram illustrating various scan lines of a primary electron beam across a sample surface applied by a charged particle beam device (such as the charged particle beam device shown in FIG. 5) consistent with embodiments of the present disclosure. FIG. 6 illustrates a top view of a field of view 601, with the primary electron beam scanning across the field of view 601 as scan lines over a time interval. Deflectors, such as deflectors 553a-553e in FIG. 5, can deflect the focused primary electron beam. Referring again to FIG. 6, the time intervals of the first scan line 610, the second scan line 611, and the third scan line 612 can each be 10 μs to 100 μs, inclusive. In some embodiments, the primary electron beam has a first probe current and is adjusted to scan the first scan line 610 over a first time interval. Prior to scanning, the electron beam may be focused by an objective lens, which may be communicatively coupled to a processor to apply and record electrical signals to generate a magnetic field that focuses the electron beam at a first probe current value. After the first scan line 610 is completed, the probe current of the primary electron beam may be adjusted, and the primary electron beam may be focus-compensated by a deflector as described above. The refocused primary electrons may be repositioned to a different position, as shown by trace line 610_1, and the primary electron beam may then be rescanned across the sample at a different probe current, as shown by scan line 611. Similarly, the probe current of the primary electron beam may be adjusted to perform a third scan, as shown by scan line 612. It should be understood that FIG. 6 is for illustrative purposes, and the width, length, and number of scan lines 610, 611, and 612 are not so limited. It should further be understood that multiple lines may be scanned across the sample at a first probe current before adjusting to a second probe current. Each probe current may be selected to produce a secondary electron yield greater than one. During each time interval, secondary electrons are emitted and collected by a corresponding detector to generate a corresponding image for each scan line. An image processing system can back-calculate the corresponding electrical characteristics of the sample field of view 601, as described above in FIG. 4. Thus, the charged particle beam device functions as a non-contact probe for determining the electrical characteristics of the sample field of view 601.

[0045]

[0053] Reference is now made to FIG. 7 , which is a schematic diagram of the top of a charged particle beam device having a stigmator consistent with embodiments of the present disclosure. The stigmator may be configured to impart a weak electric or magnetic field to the primary electron beam to reduce astigmatism of the primary electron beam. In some embodiments, a stigmator may be used instead of a condenser lens to impart a focusing effect to the primary electron beam and vary the probe current of the primary electron beam. In some embodiments, the stigmator 727 may include multiple electrodes. As described above for the condenser lens 526 of FIG. 5 , the stigmator 727 may be communicatively coupled to the controller 109, and an electrical signal may be applied to the stigmator 727. The stigmator 727 may generate a corresponding electrostatic field 727_a that may impart a focusing effect to steer the primary electron beam 705. In some embodiments, the focusing effect of the condenser lens 726 may remain constant if the stigmator 727 is configured to be an electrostatic lens. While Figure 7 shows a particular focusing effect of collecting lens 726, it should be understood that collecting lens 726 may impart any focusing effect to primary electron beam 705, while the probe current may be varied by stigmator 727, while collecting lens 726 remains constant. While Figure 7 also shows stigmator 727 imparting a focusing effect that focuses primary electron beam 705, it should be understood that stigmator 727 may impart any focusing effect to manipulate primary electron beam 705 to adjust the probe current. In some embodiments, a subset of deflectors (such as 533d or 533e in Figure 5, or both) may be used as an electrostatic lens in combination with stigmator 727 to compensate for the focus of primary electron beam 705 when the probe current is varied.

[0046]

[0054] Reference is now made to Figure 8, which is a flowchart illustrating an exemplary process for compensating electron beam focus consistent with embodiments of the present disclosure. The steps of method 800 may be performed by a charged particle beam device, such as an SEM, executed on a computing device (e.g., controller 109 of Figure 1) or otherwise using the functionality of a computing device, as described above with respect to Figures 5, 6, and 7. It should be understood that the illustrated method 800 may be modified to change the order of steps and include additional steps.

[0047]

[0055] Method 800 is a process for determining electrical characteristics of a sample device using a primary charged particle beam, such as an SEM, without directly contacting the sample. The sample device may be scanned multiple times with the primary charged particle beam at different probe currents or landing energies. Varying the probe current may result in the primary charged particle beam becoming overfocused or underfocused. Because adjusting the focus using a magnetic objective lens may reduce throughput, additional components of the charged particle beam instrument, such as an SEM, may focus compensate the primary charged particle beam. Images generated by secondary charged particles emitted from the primary charged particle beam at different probe currents or landing energies may be used to back-calculate the electrical characteristics of the sample device.

[0048]

[0056] In step S801, a first lens may steer a primary charged particle beam (such as primary electron beam 505 in FIG. 5 ) emitted by a charged particle source (such as cathode 503 in FIG. 5 ) to achieve a first probe current of the primary charged particle beam. In some embodiments, the first probe current may be selected so that the yield of emitted secondary charged particles is greater than one (such as the yield of emitted secondary electrons in FIG. 3 ). In some embodiments, the first lens may steer the primary charged particle beam to achieve the first probe current by applying a focusing effect to the primary charged particle beam. In some embodiments, the first lens is communicatively coupled to a controller (such as controller 109 in FIG. 1 ), and an electrical signal is applied to the first lens to steer the primary charged particle beam. In some embodiments, the first lens may be a condenser lens, as described above with respect to FIG. 5 . In some embodiments, the condenser lens may be a magnetic lens, an electrostatic lens, or a combined magnetic and electrostatic lens. In some embodiments, the first lens may be a stigmator lens, as described above with respect to Figure 7. In some embodiments, the stigmator lens may be an electrostatic lens.

[0049]

[0057] In step S802, the primary charged particle beam at the first probe current may be focused to a focal point substantially at the surface of a sample (such as sample 550 in FIG. 5) using an objective lens (such as objective lens 532 in FIG. 5). In some embodiments, the objective lens may be communicatively coupled to a processor that may apply an electrical signal to the objective lens to focus the primary charged particle beam at the first probe current. In some embodiments, the processor may record the intensity of the electrical signal applied to the objective lens.

[0050]

[0058] In step S803, the primary charged particle beam at the first probe current may be deflected by a deflector (such as deflectors 533a-533e in FIG. 5) to scan a first scan line across a field of view on the surface of the sample over a time interval. In some embodiments, this time interval may be 10 μs to 100 μs (inclusive), as described above with respect to FIG. 6. In some embodiments, a deflector may be used to scan the primary charged particle beam at the first probe current across the entire surface of the sample. In some embodiments, the primary charged particle beam at the first probe current may be scanned across a line on the sample. In some embodiments, the primary charged particle beam at the first probe current may be scanned across multiple lines on the sample. The primary charged particle beam at the first probe current scanning across the sample may result in a sample charging difference (such as sample voltage difference 420 in FIG. 4) and generate a sample current (such as sample current 410 in FIG. 4).

[0051]

[0059] In step S804, after scanning the first scan line, the setting of the first lens may be changed to steer the primary charged particle beam to achieve a second probe current of the primary charged particle beam. The second probe current may be different from the first probe current. The first lens may steer the primary charged particle beam to achieve the second probe current, as described above. The second probe current may be selected so that the yield of emitted secondary charged particles is greater than 1. This may result in different surfaces of the sample, generating different sample voltage differences (such as sample voltage difference 420 in FIG. 4) and sample currents (such as sample current 410 in FIG. 4).

[0052]

[0060] In step S805, the primary charged particle beam at the second probe current may use a second lens to compensate for focus variations without changing the setting of the objective lens (such as objective lens 532 in FIG. 5 ). As described above, increasing or decreasing the probe current may cause focus variations (e.g., overfocus or underfocus). As described with respect to FIG. 5 above, a deflector (such as deflector 533d) may be used to compensate. Similarly, one or more deflectors (such as deflectors 533d and 533e) may be used for compensation. Because adjusting the setting of the objective lens may take a relatively long time, during this step, the processor may apply the same electrical signal to the objective lens as was applied in step S803. In some embodiments, the second lens may be one or more deflectors, each of which includes multiple electrodes used separately or in combination. In some embodiments, the second lens may be an electrostatic lens. In some embodiments, the second lens may be communicatively coupled to the processor, and an electrical signal may be applied to all of the electrodes of the plurality of electrodes that comprise the deflector. In some embodiments, the same electrical signal may be applied to all of the electrodes of the plurality of electrodes that comprise the deflector. In some embodiments, the focusing function of the deflector may not interfere with the deflection function of the deflector.

[0053]

[0061] In step S806, the primary charged particle beam at the second probe current may be deflected by a deflector (such as 533a-533e in FIG. 5) to scan a second scan line across a field of view on the surface of the sample for a time interval. The primary charged particle beam at the second probe current may be scanned across the sample as described in the embodiment mentioned in step S803 above. The primary charged particle beam at the second probe current scanning across the sample may result in different surface charges on the sample and generate different sample currents.

[0054]

[0062] Reference is now made to Figure 9, which is a flowchart depicting an exemplary process for determining electrical characteristics of a specimen without direct contact, consistent with embodiments of the present disclosure. The steps of method 900 may be performed by a charged particle beam device, such as an SEM, executed on a computing device (e.g., controller 109 of Figure 1) or otherwise using the functionality of a computing device, as described above with respect to Figures 5, 6, and 7. It should be understood that the illustrated method 900 may be modified to change the order of steps and include additional steps.

[0055]

[0063] In step S901, a primary charged particle beam at a first probe current may be scanned in a first scan line across a field of view on the surface of the sample for a time interval. Prior to scanning, the primary charged particle beam may be manipulated to achieve a first probe current (e.g., according to step S801 of FIG. 8) and compensate for focus variations (e.g., according to step S802 of FIG. 8). The primary charged particle beam at the first probe current may be scanned across the sample as described in the embodiments detailed above (e.g., according to the description of FIG. 6 above).

[0056]

[0064] In step S902, the detector may collect a first detection data set from secondary charged particles emitted in response to the primary charged particle beam at the first probe current striking the sample over the first scan line. In some embodiments, the first detection data set may include a current of secondary charged particles emitted in response to the primary charged particle beam at the first probe current striking the sample over the first scan line. In some embodiments, the first detection data set may correspond to a first probe current selected for the primary charged particle beam, an accumulated surface charge resulting in a voltage difference (such as sample voltage difference 420 in FIG. 4 ), and a sample current (such as sample current 410 in FIG. 4 ).

[0057]

[0065] In step S903, the primary charged particle beam at the second probe current may be scanned in a second scan line across a field of view on the surface of the sample for a time interval. Prior to scanning, the primary charged particle beam may be manipulated to achieve the second probe current (e.g., according to step S804 of FIG. 8) and compensate for focus variations (e.g., according to step S805 of FIG. 8). The primary charged particle beam at the second probe current may be scanned across the sample as described in the embodiments detailed above (e.g., according to the description of FIG. 6 above).

[0058]

[0066] In step S904, the detector may collect a second detection data set from secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample over the second scan line. In some embodiments, the second detection data set may include a current of secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample over the second scan line. In some embodiments, the second detection data set may correspond to a second probe current selected for the primary charged particle beam, an accumulated surface charge resulting in a voltage difference (such as sample voltage difference 420 in FIG. 4), and a sample current (such as sample current 410 in FIG. 4).

[0059]

[0067] In step S905, an electrical characteristic of the portion of the sample may be determined based on the first and second detection data sets. In some embodiments, the electrical characteristic may be a current-voltage characteristic (e.g., resistance or capacitance).

[0060]

[0068] A non-transitory computer-readable medium may be provided that can store instructions for a processor of a controller (e.g., controller 109 of FIG. 1) to acquire an inspection image, position the stage, focus and compensate the primary charged particle beam, inspect the electrical characteristics of the sample device, adjust the electrostatic field, adjust the objective lens, activate the charged particle source, method 800 of FIG. 8, method 900 of FIG. 9, and other executable functions in a charged particle system related to focus compensation of the primary charged particle beam and non-contact nanoprobe methods. 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, compact disk read-only memory (CD-ROM), any other optical data storage medium, any physical medium with a pattern of holes, random access memory (RAM), programmable read-only memory (PROM) and erasable programmable read-only memory (EPROM), flash EPROM or any other flash memory, non-volatile random access memory (NVRAM), cache, registers, any other memory chip or cartridge, and network-connected versions thereof.

[0061]

[0069] The embodiments may be further described using the following clauses. 1. A charged particle beam device for inspecting a specimen, comprising: a charged particle source configured to emit a primary charged particle beam; a first lens configured to steer the primary charged particle beam to adjust a probe current of the primary charged particle beam; an objective lens configured to focus the primary charged particle beam to a focal point substantially on the surface of the sample; a second lens configured to generate an electrostatic field that substantially overlaps with the magnetic field generated by the objective lens and to compensate for focus variations caused by changes in probe current without changing the focusing power of the objective lens, the changes in probe current being caused by the first lens; and a deflector configured to deflect the primary charged particle beam to scan a scan line of a field of view of the sample; A charged particle beam device comprising: 2. The device of clause 1, wherein the first lens is a magnetic lens. 3. The apparatus of clause 1, wherein the first lens is an electrostatic lens. 4. The apparatus of clause 1, wherein the first lens is a compound magnetic and electrostatic lens. 5. The device of clause 3 or 4, wherein the first lens comprises a plurality of electrodes. 6. The apparatus of clause 5, wherein the electrical signal is applied to multiple electrodes. 7. The device of any one of clauses 1 to 4, wherein the first lens is a focusing lens. 8. The device of any one of clauses 1 to 4, wherein the first lens is a stigmator. 9. The apparatus of clause 1, wherein the second lens is an electrostatic lens. 10. The device of clause 9, wherein the second lens comprises a plurality of electrodes. 11. The device of clause 10, wherein the electrical signal is applied to multiple electrodes. 12. The apparatus of clause 11, wherein the same electrical signal is applied to all of the plurality of electrodes. 13. The apparatus of clause 1, wherein the second lens is a deflector. 14. The apparatus of clause 1, further comprising a charged particle detector configured to collect charged particle data from secondary charged particles emitted in response to the primary charged particle beam striking the sample. 15. The apparatus of clause 14, wherein the charged particle detector includes circuitry configured to determine an electrical characteristic of the sample based on the collected charged particle data without direct contact with the sample. 16. A charged particle beam device for inspecting a specimen, comprising: a charged particle source configured to emit a primary charged particle beam; a first lens configured to steer the primary charged particle beam to adjust a probe current level of the primary charged particle beam; an objective lens configured to focus the primary charged particle beam to a focal point substantially on the surface of the sample; a plurality of deflectors configured to deflect the primary charged particle beam to scan a scan line of a field of view of the sample, a subset of the plurality of deflectors being further configured to generate an electrostatic field that substantially overlaps with a magnetic field generated by the objective lens and to also compensate for focus variations caused by changes in probe current level, the changes in probe current level being caused by the first lens; A charged particle beam device comprising: 17. The apparatus of clause 16, wherein the first lens is a magnetic lens. 18. The apparatus of clause 16, wherein the first lens is an electrostatic lens. 19. The apparatus of clause 16, wherein the first lens is a compound magnetic and electrostatic lens. 20. The apparatus of clause 18 or 19, wherein the first lens comprises a plurality of electrodes. 21. The device of clause 20, wherein the electrical signal is applied to multiple electrodes. 22. The device of any one of clauses 16 to 19, wherein the first lens is a focusing lens. 23. The device of any one of clauses 16 to 19, wherein the first lens is a stigmator. 24. The apparatus of clause 16, wherein a subset of the plurality of deflectors are electrostatic lenses. 25. The apparatus of clause 24, wherein each deflector of the subset of the plurality of deflectors includes a plurality of electrodes. 26. The device of clause 25, wherein the electrical signal is applied to multiple electrodes. 27. The apparatus of clause 26, wherein the same electrical signal is applied to all of the plurality of electrodes. 28. A method of adjusting the focus of a charged particle beam for inspecting a specimen, comprising: using a first lens to manipulate a primary charged particle beam emitted by the charged particle source to change a current of the primary charged particle beam into a first probe current; focusing a primary charged particle beam at a first probe current to a focal point substantially at a surface of the sample using an objective lens; scanning a first scan line of a field of view of the sample with a primary charged particle beam at a first probe current; After scanning the first scan line, using a first lens to steer the primary charged particle beam to change the current of the primary charged particle beam to a second probe current; using a second lens to compensate for focus variations of the primary charged particle beam at the second probe current without changing the setting of the objective lens; scanning a second scan line of the field of view of the sample with the primary charged particle beam at a second probe current, the first line scan and the second line scan being performed sequentially; A method comprising: 29. The method of clause 28, wherein the first lens is a magnetic lens. 30. The method of clause 28, wherein the first lens is an electrostatic lens. 31. The method of clause 28, wherein the first lens is a combined magnetic and electrostatic lens. 32. The method of clause 30 or 31, wherein the first lens includes a plurality of electrodes. 33. The method of clause 32, further comprising applying an electrical signal to a plurality of electrodes. 34. The method of any one of clauses 28 to 31, wherein the first lens is a focusing lens. 35. The method of any one of clauses 28 to 31, wherein the first lens is a stigmator. 36. The method of clause 28, wherein the second lens is an electrostatic lens. 37. The method of clause 36, wherein the second lens includes a plurality of electrodes. 38. The method of clause 37, further comprising applying an electrical signal to a plurality of electrodes. 39. The method of clause 38, further comprising applying the same electrical signal to all of the plurality of electrodes. 40. The method of clause 28, wherein the second lens is a deflector. 41. Collecting charged particle detection data from secondary charged particles emitted in response to the primary charged particle beam at the first probe current striking the sample; collecting charged particle detection data from secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample; 29. The method of clause 28, further comprising: 42. The method of clause 41, further comprising determining an electrical characteristic of the sample based on charged particle detection data from the primary charged particle beam at the first probe current and the second probe current impinging on the sample. 43. The method of clause 28, wherein the scanning of the first line and the scanning of the second line are performed sequentially, without the scanning of any other line occurring in between. 44. A method of inspecting a specimen using a charged particle beam device configured to direct a charged particle beam onto the specimen, comprising: scanning a first scan line of a field of view of the sample with the charged particle beam at a first probe current; collecting a first detection data set from secondary charged particles emitted in response to the charged particle beam striking the sample across a first scan line; scanning a second scan line of the field of view of the sample with the charged particle beam at a second probe current, the scanning of the first scan line and the scanning of the second scan line being performed sequentially; collecting a second detection data set from secondary charged particles emitted in response to the charged particle beam striking the sample over a second scan line; determining a current-voltage characteristic of the portion of the sample based on the first detected data set and the second detected data set; A method comprising: 45. The method of clause 44, wherein the scanning of the first scan line and the scanning of the second scan line are performed sequentially, without the scanning of any other lines occurring in between. 46. ​​The method according to clause 44, wherein the current-voltage characteristic is the resistance or capacitance of the sample. 47. The method of clause 44, further comprising identifying specimen defects by comparing the current-voltage characteristic to an expected current-voltage characteristic of a portion of the specimen. 48. A non-transitory computer-readable medium storing a set of instructions executable by one or more processors of a charged particle beam device to cause the charged particle beam device to perform a method of inspecting a specimen, the method comprising: using a first lens to manipulate a primary charged particle beam emitted by the charged particle source to change a current of the primary charged particle beam into a first probe current; focusing a primary charged particle beam at a first probe current to a focal point substantially at a surface of the sample using an objective lens; scanning a first scan line of a field of view of the sample with a primary charged particle beam at a first probe current; After scanning the first scan line, using a first lens to steer the primary charged particle beam to change the current of the primary charged particle beam to a second probe current; using a second lens to compensate for focus variations of the primary charged particle beam at the second probe current without changing the setting of the objective lens; scanning a second scan line of the field of view of the sample with the primary charged particle beam at a second probe current, the first line scan and the second line scan being performed sequentially; 1. A non-transitory computer-readable medium comprising: 49. The non-transitory computer-readable medium of clause 48, wherein the scanning of the first line and the scanning of the second line are performed sequentially, without the scanning of any other line occurring in between. 50. The non-transitory computer-readable medium of clause 48, wherein the first lens is a magnetic lens. 51. The non-transitory computer-readable medium of clause 48, wherein the first lens is an electrostatic lens. 52. The non-transitory computer-readable medium of clause 48, wherein the first lens is a combined magnetic and electrostatic lens. 53. The non-transitory computer-readable medium of clause 51 or 52, wherein the first lens includes a plurality of electrodes. 54. The non-transitory computer-readable medium of clause 53, wherein the electrical signal is applied to a plurality of electrodes. 55. The non-transitory computer-readable medium of any one of clauses 48 to 52, wherein the first lens is a focusing lens. 56. The non-transitory computer-readable medium of any one of clauses 48 to 52, wherein the first lens is a stigmator. 57. The non-transitory computer-readable medium of clause 48, wherein the second lens is an electrostatic lens. 58. The non-transitory computer-readable medium of clause 57, wherein the second lens includes a plurality of electrodes. 59. The non-transitory computer-readable medium of clause 58, wherein the electrical signal is applied to a plurality of electrodes. 60. The non-transitory computer-readable medium of clause 59, wherein the same electrical signal is applied to all of the plurality of electrodes. 61. The non-transitory computer-readable medium of clause 48, wherein the second lens is a deflector. 62. A set of instructions for a charged particle beam device, comprising: collecting charged particle detection data from secondary charged particles emitted in response to the primary charged particle beam at the first probe current striking the sample; collecting charged particle detection data from secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample; 49. The non-transitory computer-readable medium of claim 48, wherein the non-transitory computer-readable medium is a set of instructions executable by one or more processors to cause the 63. The non-transitory computer readable medium of clause 62, the set of instructions being executable by one or more processors to further cause the charged particle beam device to determine electrical properties of the sample based on charged particle detection data from the primary charged particle beam at the first probe current and the second probe current impinging on the sample.

[0062] It will be understood that the embodiments of the present disclosure are not limited to the exact construction described above and illustrated in the accompanying drawings, and that various modifications and changes can be made therein without departing from the scope thereof. While the present disclosure has been described in connection with various embodiments, other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

1. 1. A charged particle beam device for inspecting a specimen, comprising: a charged particle source that emits a primary charged particle beam; a first lens for manipulating the primary charged particle beam to adjust a probe current of the primary charged particle beam; an objective lens for focusing the primary charged particle beam to a focal point substantially on the surface of the sample; a second lens that generates an electrostatic field that substantially overlaps with the magnetic field generated by the objective lens and that also compensates for focus variations caused by changes in probe current without changing the focusing power of the objective lens, the changes in probe current being caused by the first lens; and a deflector for deflecting the primary charged particle beam to scan a scan line of a field of view of the sample; A charged particle beam device comprising:

2. The apparatus of claim 1 , wherein the first lens is a magnetic lens.

3. The apparatus of claim 1 , wherein the first lens is an electrostatic lens.

4. The apparatus of claim 1 , wherein the first lens is a compound magnetic and electrostatic lens.

5. The apparatus of claim 3 , wherein the first lens includes a plurality of electrodes.

6. The apparatus of claim 5 , wherein an electrical signal is applied to the plurality of electrodes.

7. The apparatus of claim 1 , wherein the first lens is a focusing lens.

8. The apparatus of claim 1 , wherein the first lens is a stigmator.

9. The apparatus of claim 1 , wherein the second lens is an electrostatic lens.

10. The apparatus of claim 9 , wherein the second lens comprises a plurality of electrodes.

11. The apparatus of claim 10 , wherein an electrical signal is applied to the plurality of electrodes.

12. The apparatus of claim 11 , wherein the same electrical signal is applied to all of the plurality of electrodes.

13. The apparatus of claim 1 , wherein the second lens is a deflector.

14. 10. The apparatus of claim 1, further comprising a charged particle detector that collects charged particle data from secondary charged particles emitted in response to the primary charged particle beam striking the sample, the charged particle detector comprising circuitry that determines an electrical characteristic of the sample based on the collected charged particle data without direct contact with the sample.

15. 1. A non-transitory computer-readable medium storing a set of instructions executable by one or more processors of a charged particle beam device to cause the device to perform a method for inspecting a specimen, the method comprising: using a first lens to manipulate a primary charged particle beam emitted by a charged particle source to change the current of the primary charged particle beam into a first probe current; focusing the primary charged particle beam at the first probe current to a focal point substantially at the surface of the sample using an objective lens; scanning a first scan line of a field of view of the sample with the primary charged particle beam at the first probe current; After scanning the first scan line, steering the primary charged particle beam using the first lens to change the current of the primary charged particle beam to a second probe current; using a second lens to compensate for focus variations of the primary charged particle beam at the second probe current without changing the setting of the objective lens; scanning a second scan line of a field of view of the sample with the primary charged particle beam at the second probe current, wherein the first line scan and the second line scan are performed sequentially; and 1. A non-transitory computer-readable medium comprising:

Images