Charged particle beam detection device and method

Abstract

Disclosed herein are a charged particle beam detection apparatus for detecting a sample (550) and a charged particle beam conditioning technique, and more particularly, a charged particle beam non-contact electrical characterization technique (e.g., for defect detection). The charged particle beam apparatus comprises: 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 to a focal point substantially located on the sample surface; a second lens (533d, e) configured to generate an electrostatic field substantially overlapping the magnetic field generated by the objective lens, and compensate for a change in focus caused by a change in probe current, which is caused by the first lens, without changing the objective lens light angle; and a deflector (533a-e) configured to deflect the primary charged particle beam to scan a scan line of the sample field of view.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application 63 / 434,338, filed on December 21, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments provided herein disclose a charged particle beam inspection apparatus and a charged particle beam adjustment technique, and more particularly, disclose a non-contact electrical characterization technique using the charged particle beam inspection apparatus. The charged particle beam apparatus can be used to rapidly change charged particle beam parameters to determine the electrical properties of a sample without direct contact. Background Art

[0004] In the manufacturing process of integrated circuits (ICs), unfinished or completed circuit components are inspected to ensure that they are manufactured according to the design, are free of defects, and have the desired electrical characteristics. An inspection system utilizing an optical microscope or a charged particle (e.g., electron) beam microscope (e.g., a scanning electron microscope (SEM)) can be used. As the physical size of IC components continues to shrink, the accuracy and yield of IC inspections become increasingly important. In an SEM, a primary electron beam with relatively high energy is decelerated and lands on a sample with a relatively low landing energy and is focused to form a detection point thereon. Due to the focused detection point of this primary electron, secondary electrons will be generated from the surface. The secondary electrons are detected by an electron detector to produce an SEM image of the sample.

[0005] Inspection images, such as SEM images, can be used to identify or classify defects in manufactured ICs. To examine the electrical properties of small IC device structures, an SEM applies an electrical signal to a sample and measures the corresponding response. However, rapid adjustments to the electron beam current and focus are required to generate an IV curve of the sample. To improve defect detection and electrical characterization studies, inspection tools and methods are needed that increase throughput while maintaining IC structural fidelity. Summary of the Invention

[0006] The embodiments provided herein disclose a charged particle beam system for examining a sample, and more particularly, disclose a charged particle beam system for examining a sample including an improved fast focus compensation mechanism.

[0007] Some embodiments provide a charged particle beam apparatus for examining a sample. The apparatus includes: 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 to a focus substantially on a sample surface; a second lens configured to generate an electrostatic field that substantially overlaps with a magnetic field generated by the objective lens and further compensates for focus changes caused by changes in the probe current without changing the optical power of the objective lens, wherein 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 sample.

[0008] In some embodiments, a non-transitory computer-readable medium storing an instruction set is provided, the instruction set being 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 comprises: manipulating a primary charged particle beam emitted by a charged particle source with a first lens to change a current of the primary charged particle beam to a first probe current; focusing the primary charged particle beam at the first probe current to a focus substantially at a sample surface with 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, manipulating the primary charged particle beam with the first lens to change the current of the primary charged particle beam to a second probe current; compensating for a focus change of the primary charged particle beam at the second probe current with a second lens 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 scanning the first line and scanning the second line are performed sequentially.

[0009] Other advantages of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings, which illustrate certain embodiments of the present disclosure by way of illustration and example. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other aspects of the present disclosure will become more apparent from the following description of exemplary embodiments with reference to the attached drawings.

[0011] Figure 1 is a schematic diagram illustrating an exemplary charged particle beam inspection system according to an embodiment of the present disclosure.

[0012] Figure 2 is a schematic diagram illustrating an exemplary charged particle beam tool according to an embodiment of the present disclosure.

[0013] Figure 3 is an example graph showing the yield of secondary electrons relative to the landing energy of primary electrons.

[0014] Figure 4is a schematic diagram showing the voltage contrast response of a sample when an electron beam strikes the sample.

[0015] Figure 5 is a schematic diagram illustrating an example charged particle beam apparatus for examining electrical characteristics of a sample according to an embodiment of the present disclosure.

[0016] Figure 6 is a schematic diagram illustrating an example scan line of a focused electron beam across a sample surface applied by a charged particle beam apparatus according to an embodiment of the present disclosure.

[0017] Figure 7 is a schematic diagram of a top portion of an example charged particle beam apparatus including an astigmatism corrector according to an embodiment of the present invention.

[0018] Figure 8 is a flow chart representing an exemplary process for compensating the focus of a charged particle beam according to an embodiment of the present disclosure.

[0019] Figure 9 is a flow chart representing an exemplary process for inspecting electrical characteristics of a sample without direct contact according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] 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 like numerals in different figures represent the same or similar elements, unless otherwise specified. The implementations set forth in the following description of the exemplary embodiments are not intended to represent all implementations consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with aspects related to the present invention as described in the appended claims.

[0021] The increased computing power of electronic devices can be achieved by significantly increasing the packaging density of circuit components such as transistors, capacitors, diodes, etc. on IC chips while reducing the physical size of the devices. For example, a thumbnail-sized IC chip in a smartphone can include over 2 billion transistors, each less than 1 / 1000 the size of a human hair. It is therefore not surprising that semiconductor IC manufacturing is a complex and time-consuming process with hundreds of individual steps. An error in even a single step can significantly affect the functionality of the final product. Even a single "fatal defect" can cause device failure. A goal of the manufacturing process is to increase the overall yield of the process. For example, to achieve a 75% yield in a 50-step process, each individual step must have a yield greater than 99.4%. If the individual step yield is 95%, the overall process yield drops to 7%.

[0022] While high process yields are desirable in IC chip manufacturing facilities, it is also necessary to maintain high wafer throughput (defined as the number of wafers processed per hour). High process yields and high wafer throughput can be impacted by the presence of defects, particularly if operator intervention is required to detect the defects. Therefore, high-throughput detection and identification of micro- and nano-scale defects by inspection tools (e.g., SEM) is essential to maintaining high yields and low costs.

[0023] The SEM scans the surface of a sample with a focused electron beam. The electrons interact with the sample and generate secondary electrons. By scanning the sample with the electron beam and capturing the secondary electrons with a detector, the SEM produces an image of the sample that reveals the internal device structure underlying the inspected sample area. Traditional SEM inspection tools acquire a single image of the sample area and compare it with a reference image representing a corresponding device structure free of defects. Differences detected from the image comparison can indicate defects in the sample.

[0024] Nanoprobing techniques can be used with an SEM to obtain electrical properties of a sample (e.g., resistance, capacitance, etc.). For example, an SEM can determine the electrical characteristics or properties of a sample by applying an electrical signal through an electron beam that impinges on the sample and measuring the corresponding electrical response. In order to fully analyze the electrical characteristics of a sample, a current and voltage relationship (e.g., an IV curve) can be generated by adjusting the current of the electron beam in the SEM to induce different electrical responses of the sample. However, due to the slow adjustment process, conventional SEM systems cannot support rapid adjustment of the electron beam current. Therefore, the ability to extract certain I / V information is undesirably limited because the user cannot, for example, quickly scan a node multiple times in rapid succession with different probe currents for each scan.

[0025] Embodiments of the present disclosure may provide an electron beam inspection device for rapidly and continuously scanning a sample multiple times with different electron beam parameters, which makes it possible to determine the electrical characteristics or properties (e.g., IV curve) of the sample without direct contact. Embodiments of the present disclosure may provide an electrostatic lens that can quickly compensate the focus of the electron beam when adjusting the current of the electron beam. During this focus adjustment, the objective lens can remain constant, so less energy and time are required to focus the electron beam onto the sample and thus measure the electrical characteristics or properties of the sample. Therefore, the disclosed electron beam inspection device is able to support rapid electron beam parameter adjustment and determine the IV curve of the sample that cannot be obtained 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 particles can be used in any embodiment of the present invention, and it is not limited to electrons.

[0026] For clarity, the relative sizes of parts in the drawings may be exaggerated. In the following description of the drawings, the same or similar reference numerals refer to the same or similar components or entities, and only the differences with respect to the various embodiments are described. As used herein, unless otherwise specifically stated, the term "or" encompasses all possible combinations unless not feasible. For example, if it is stated that a database can include A or B, then, unless specifically stated or not feasible, the database can include A, or B, or A and B. As a second example, if it is stated that a database can include A, B, or C, then, unless specifically stated or not feasible, the database can include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0027] Now refer to Figure 1 , Figure 1 FIG is a schematic diagram illustrating an exemplary charged particle beam inspection system 100 according to an embodiment of the present disclosure. Figure 1 As shown, the charged particle beam inspection system 100 includes a main chamber 101, a load lock chamber 102, an electron beam tool 104, and an equipment front end module (EFEM) 106. The electron beam tool 104 is located within the main chamber 101. Although the description and drawings are directed to electron beams, it should be understood that these embodiments are not intended to limit the present disclosure to specific charged particles.

[0028] The EFEM 106 includes a first load port 106a and a second load port 106b. The EFEM 106 may include additional load ports. For example, the first load port 106a and the second load port 106b may receive front-opening pods (FOUPs) containing samples (e.g., semiconductor wafers or wafers made of other materials) or samples to be inspected (wafers and samples are collectively referred to as "samples" hereinafter). One or more robotic arms (not shown) in the EFEM 106 transport the samples to the load lock chamber 102.

[0029] The load lock chamber 102 can be connected to a load lock vacuum pump system (not shown), which removes gas molecules from the load lock chamber 102 to reach a first pressure lower than atmospheric pressure. After reaching the first pressure, one or more robotic arms (not shown) transport the sample from the load lock chamber 102 to the main chamber 101. The main chamber 101 is connected to a main chamber vacuum pump system (not shown), which removes gas molecules from the main chamber 101 to reach a second pressure lower than the first pressure. After reaching the second pressure, the sample is inspected by the electron beam tool 104. In some embodiments, the electron beam tool 104 may include a single-beam electron inspection tool.

[0030] The controller 109 is electrically 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. Figure 1 106, but it should be understood that the controller 109 can be part of the structure. Although the present disclosure provides an example of a main chamber 101 housing an electron beam inspection tool, it should be noted that the aspects of the present disclosure, in its broadest sense, are not limited to chambers housing electron beam inspection tools. Rather, it should be understood that the principles described above can also be applied to other tools operating at a second pressure.

[0031] Now refer to Figure 2 , Figure 2 is a schematic diagram illustrating an example imaging system 200 including an electron beam tool 104 and an image processing system 290 according to an embodiment of the present disclosure. Figure 2 As shown, the electron beam tool 104 may include a motorized stage 234 to support a sample 250 to be inspected. The electron beam tool 104 may also include an objective lens 232, an electron detector 244 (which includes an electron sensor surface), a focusing lens 226, a Coulomb aperture 224, a gun aperture 222, an anode 220, and a cathode 203, one or more of which may be aligned with the optical axis 201 of the electron beam tool 104. In some embodiments, the detector 244 may be arranged offset from the optical axis 201.

[0032] The objective lens 232 may include a modified swinging objective retarding immersion lens (SORIL), which may include an objective lens body 232a and an objective lens excitation coil 232b. Within the objective lens 232 may be a deflector or a set of deflectors 233. The electron beam tool 104 may additionally include an energy dispersive X-ray spectrometer (EDS) detector (not shown) to characterize the material on the sample.

[0033] By applying a voltage between the anode 220 and the cathode 203, a primary electron beam 204 can be emitted from the cathode 203. The primary electron beam 204 can pass through a gun aperture 222 and a Coulomb aperture 224, both of which can determine the current of the primary electron beam 204 entering a focusing lens 226, which is located below the Coulomb aperture 224. The focusing lens 226 can focus the primary electron beam 204 before the electron beam enters a current limiting aperture 235 to set the current of the electron beam before entering the objective lens 232. The set current of the primary electron beam 204 entering the objective lens 232 can be referred to as a probe current.

[0034] The objective lens 232 can focus the primary electron beam 204 onto the sample 250 for inspection, and can form a detection point 240 on the surface of the sample 250. The deflector(s) 233 can deflect the primary electron beam 204 to scan the detection point 240 on the sample 250. For example, during the scanning process, the deflector(s) 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 time points to provide data for image reconstruction of different parts of the sample 250. In addition, the deflector 233 can also be controlled to deflect the primary electron beam 204 to different sides of the sample 250 at a specific position and at different time points to provide data for stereoscopic image reconstruction of the sample structure at that position.

[0035] When an electrical signal is applied to the objective lens excitation coil 232b, an axially symmetric (i.e., symmetrical 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. The electrostatic field can reduce the energy of the primary electron beam 204 that strikes the sample surface before the electrons of the electron beam collide with the sample 250.

[0036] Secondary electrons 205 may be emitted from a portion of the sample 250 upon receiving the primary electron beam 204. Figure 2 205 , which is shown in FIG. 206 , but 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 the 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 may 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 includes defects. Furthermore, as described above, the primary electron beam 204 may be projected onto different locations on the top surface of the sample 250, or onto different sides of the sample 250 at a particular location, to generate secondary electrons 205 of varying intensities. Thus, by mapping the intensity of the emitted secondary electrons 205 over regions of the sample 250, the image processing system 290 may reconstruct an image reflecting features of the internal or external structure of the sample 250.

[0037] The imaging system 200 may also include an image processing system 290, which includes an image acquirer 292, a memory 294, and the controller 109. The image acquirer 292 may include one or more processors. For example, the image acquirer 292 may include a computer, a server, a mainframe, a terminal, a personal computer, any type of mobile computing device, or a combination thereof. The image acquirer 292 may be communicatively coupled to the detector 244 of the electron beam tool 104 via a medium such as an electrical conductor, a fiber optic cable, a portable storage medium, IR, Bluetooth, the internet, a wireless network, radio, or a combination thereof. The image acquirer 292 may receive signals from the detector 244 and construct an image. Thus, the image acquirer 292 may acquire an image of the sample 250. The image acquirer 292 may also perform various post-processing functions, such as generating outlines and overlaying indicators on the acquired image. The image acquirer 292 may be configured to adjust the brightness and contrast of the acquired image. The memory 294 may be a storage medium such as a hard drive, a flash drive, cloud storage, random access memory (RAM), or other types of computer-readable memory. The memory 294 can be coupled to the image acquirer 292 and can be used to save the scanned raw image data as a raw image and a post-processed image. The image acquirer 292 and the memory 294 can be connected to the controller 109. The image acquirer 292, the memory 294 and the controller 109 can be integrated together as a control unit.

[0038] The image acquirer 292 can acquire one or more images of the sample based on the imaging signal received from the detector 244. The imaging signal can correspond to a scanning operation for performing charged particle imaging. The acquired image can be a single image including multiple imaging regions. The single image can be stored in the memory 294. The single image can be an original image that can be divided into multiple regions. Each region can include an imaging region that includes a feature of the sample 250. The acquired image can include multiple images of a single imaging region of the sample 250 sampled multiple times in a time series. The multiple images can be stored in the memory 294. The image processing system 290 can be configured to perform image processing steps using multiple images of the same position of the sample 250.

[0039] Image processing system 290 may include measurement circuitry (e.g., an analog-to-digital converter) to obtain a distribution of the detected secondary electrons. The electron distribution data collected during the detection time window, combined with corresponding scan path data of primary electron beam 204 incident on the sample surface, can be used to reconstruct an image of the inspected sample structure. The reconstructed image can be used to reveal various features of the internal or external structure of sample 250, thereby revealing any defects that may be present in the sample.

[0040] Now refer to Figure 3 , Figure 3 is an example graph showing the yield of emitted secondary electrons relative to the landing energy of the primary electrons. Figure 2 The landing energy or current of the primary electron beam 204 in the Figure 2 The relationship between the yield of secondary electrons 205 in the sample and the yield of emitted secondary electrons 205 is shown in Table 1. 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 a greater number of secondary electrons can 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 can be emitted in response to primary electrons striking the sample.

[0041] like Figure 3 As shown in the graph, when the landing energy of the primary electrons is in the range of E1 to E2, more secondary electrons are emitted from the sample surface than primary electrons strike the surface, thus generating a positive potential or voltage at the sample surface. Samples with a more positive surface potential can produce darker voltage contrast images because the detector can receive fewer secondary electrons.

[0042] Now refer to Figure 4 , Figure 4 is a schematic diagram showing the voltage contrast response of a sample when a primary electron beam strikes the sample according to an embodiment of the present disclosure. Figure 2 When an electron beam tool 104 (electron beam tool 104) 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 number of incident electrons from the primary electron beam 404 that strike the surface of the sample 450 determines the yield of emitted secondary electrons as described above. The field of view of the sample 450 may have different microstructures 450_1, 450_2, and 450_3. In Figure 4 In the example shown, microstructure 450_2 is struck by a primary electron beam 404 and, in response, emits secondary electrons 405 from sample 450. Secondary electrons 405 can be collected and measured by a detector.

[0043] As above about Figure 3 As described above, by appropriately adjusting the landing energy of the primary electron beam (e.g., primary electron beam 404), the emission yield of secondary electrons can be controlled. For example, an appropriate landing energy between E1 and E2 can be selected so that the yield of secondary electrons is greater than 1, which can result in the surface of the sample microstructure 450_2 being positively charged, as shown in FIG. Figure 4 Return to reference Figure 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 the substrate 460, which may be electrically grounded. As a result, a sample current 410 may flow through the microstructure 450_2. Figure 3 As discussed, changing the landing energy of the primary electron beam affects the number of secondary electrons emitted. Figure 4 , the landing energy of the primary electron beam 404 can be kept constant, while the probe current of the primary electron beam 404 can be varied. This, in turn, can change the emission yield of secondary electrons and the voltage difference 420. Therefore, controlling the probe current of the primary electron beam 404 can change the voltage difference 420 and the sample current 410. The sample 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. An image of the sample 450 with the microstructure 450_2 can be generated by an image processing system or controller using the signals collected from the detector measuring the emitted secondary electrons 405. The voltage contrast of the image can be used to reversely calculate the secondary electron yield and the voltage difference 420.

[0044] Sample characteristics of the microstructure 450_2 (such as resistance, capacitance, and other electrical characteristics) can be calculated based on reverse calculations and measured values. For example, the resistance value can be determined by dividing the calculated sample voltage difference 420 by the calculated sample current 410. As a form of defect detection, the calculated resistance value can be compared with a standard resistance value of the sample (e.g., an expected resistance based on the design parameters of the device structure). A calculated resistance value that is significantly different from the standard resistance value of the sample can indicate the presence of a defect in the imaged sample area. In order to more thoroughly analyze the electrical characteristics of the sample, the probe current of the primary electron beam 404 can be changed so that the yield of emitted secondary electrons is greater than 1, such as Figure 3 See also Figure 4 , the probe current of the primary electron beam 404 can be adjusted, and the primary electron beam 404 can be rescanned across the sample 450. This can produce a different yield of emitted secondary electrons, thereby producing a second set of values of the sample current 410 and the sample voltage difference 420 as described above. This can be repeated multiple times, where each probe current can be selected so that a different sample voltage difference can be produced 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 the microstructure 450_2.

[0045] Now refer to Figure 5 , Figure 5is a schematic diagram illustrating an example charged particle beam apparatus for examining electrical properties of a sample according to an embodiment of the present disclosure. The charged particle beam apparatus may include a cathode 503, a Coulomb aperture 524, a converging lens 526, a current limiting aperture 535, an objective lens 532, and a plurality of 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 converging lens 526. The converging lens 526 may focus the primary electron beam 505 before the primary electron beam 504 enters the current limiting aperture 535. The objective lens 532 may then focus the primary electron beam 505 onto the surface of the sample 550.

[0046] In some embodiments, the controller 109 can be communicatively coupled to the converging lens 526, the current limiting aperture 535, the electron detector (not shown), and the objective lens excitation coil 532b to provide an electrical signal (e.g., current, voltage). In some embodiments, the controller 109 can be communicatively coupled to a deflector (e.g., deflector 533d) to provide an electrical signal. In some embodiments, the converging lens 526 can be used to control the probe current of the primary electron beam 505, which determines the landing energy of the primary electrons, as described above. Figure 2 and Figure 3 As explained in . The controller 109 may provide an electrical signal to the converging lens 526 to generate a magnetic field 526_a, which may provide a focusing effect (e.g., collimation or focusing) to steer the primary electron beam 505. The strength of the electrical signal provided by the controller 109 to the converging lens 526 determines the strength of the magnetic field 526_a and affects the strength of the focusing effect on the primary electron beam 505. Figure 5 As shown, an electrical signal applied to the converging lens 526 focuses the primary electron beam 505. Consequently, a certain concentration of electrons in the primary electron beam 505 passes through the current-limiting aperture 535 to determine the diameter of the primary electron beam 505 and the corresponding probe current. Dashed line 505_1 serves as an illustrative path that electrons in the primary electron beam 505 follow 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 electrons in the primary electron beam 505 that are blocked, the greater the probe current. It will be appreciated that the current-limiting aperture 535 can have a constant width, so that the converging lens 526 can control the probe current of the primary electron beam 505. It will also be appreciated that the current-limiting aperture 535 can be adjustable.

[0047] The converging lens 526 can be adjusted to change the probe current of the primary electron beam 505. This change in probe current may cause the primary electron beam 505 to be out of focus when it strikes the surface of the sample 550. The objective lens 532 typically needs to be adjusted to refocus the primary electron beam 505, but this is typically a slow adjustment because the objective lens 532 is a magnetic component. This can therefore reduce the throughput of sample analysis. In some embodiments, Figure 5Other components of the exemplary charged particle apparatus shown in can be used to compensate for focus variations with variations in the probe current of the primary electron beam 505 without adjusting the optical power of the objective lens 532 .

[0048] 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 constant intensity to the primary electron beam 505, then even after the focusing effect of the converging lens 526 is changed (for example, the focus of the primary electron beam 505 is adjusted) to increase or decrease the probe current of the primary electron beam 505, the objective lens 532 will cause the primary electron beam 505 to be underfocused or overfocused onto the sample 550 (i.e., for an underfocused primary electron beam 505, the focus will be below the sample 550, and for an overfocused primary electron beam 505, the focus will be above the sample 550). Figure 5 The dotted line 505a in FIG. 5 shows an underfocusing situation. In order to compensate for the underfocusing or overfocusing effect (i.e., focus variation), in some embodiments, the deflector 533d can be used as an electrostatic lens. For example, the controller 109 can apply a DC bias electrical signal to the deflector 533d, which can include a plurality of electrodes. When the DC bias electrical signal is applied to all electrodes, the deflector 533d can be used as an electrostatic lens as well as a deflector. The deflector 533d can generate a corresponding electrostatic field 533d_a, which can provide a focusing effect to the primary electron beam 505 to compensate for the underfocusing or overfocusing effect caused by the change in the probe current. The solid line 505b shows the compensated (refocused) primary electron beam 505. During this process, the field strength of the magnetic field 532b_a can remain the same as when only the magnetic field 532b_a applies a focusing effect to the primary electron beam 505.

[0049] 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 have a minimal impact on the fluctuation of the magnification and resolution of the primary electron beam 505. Adjusting the settings of a magnetic lens is generally slower than adjusting the settings of an electrostatic lens, so using the deflector 533d rather than changing the magnetic objective lens 532 to compensate for focus can minimize the impact on throughput. Because the deflector 533d acts as an electrostatic lens, changing the field strength of the electrostatic field 533d_a can 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 can have a small inner diameter so that the electrical signal required to compensate for focus is lower than the electrical signal required to adjust the objective lens 532. This helps to achieve fast focus compensation. In some embodiments, the electrical signal applied to the deflector 533d to compensate for the focus of the primary electron beam 505 may not interfere with the deflection function of the deflector 533d, so that the deflector 533d functions as an electrostatic lens as well as a deflector. In some embodiments, when performing local measurements with a small field of view, the deflector 533d used for focus compensation may be separated from the scanning deflector (such as deflector 533b or 533c).

[0050] although Figure 5 An embodiment using deflector 533d to compensate for overfocus or underfocus effects is described, but it should be understood that other components can be used for compensation. For example, in some embodiments, instead of deflector 533d, a deflector positioned below the objective lens (e.g., deflector 533e or objective lens control electrode (not shown)) can be used to compensate for overfocus or underfocus effects. Since deflector 533e is positioned closer to sample 550 than deflector 533d, the electrical signal applied to deflector 533e to compensate for focus may not need to be as strong as 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 deflectors 533d and 533e may require even smaller electrical signals, thereby reducing the required energy input to compensate for the focus of the primary electron beam 505 when adjusting the probe current. Additionally, larger adjustments to the probe current of the primary electron beam 505 may require a large amount of focus compensation, so both deflectors 533d and 533e may be used.

[0051] Furthermore, while the converging lens 526 can be a magnetic lens as described above, it will be appreciated that other configurations of the converging lens 526 can be utilized. For example, in some embodiments, the converging lens 526 can be an electrostatic lens. In embodiments where the converging lens 526 can be an electrostatic lens, adjusting the probe current (using the converging lens 526) and compensating for focus (using the deflectors 533d, 533e, or both) can be entirely electrostatically controlled processes that are faster than using magnetic components. In some embodiments, the converging lens 526 can be a composite magnetic and electrostatic lens used in conjunction with the deflectors 533d, 533e, or both as described above. In some embodiments, the magnetic components of the converging lens can remain the same, while the electrostatic components can be varied to adjust the probe current and increase the throughput of adjusting the probe current and compensating for focus as described above.

[0052] The focused primary electron beam 505 that strikes the sample 550 may emit corresponding secondary electrons that may be collected and measured by corresponding detectors (not shown). The image processing system 590 may then generate an image of the sample 550 based on the intensity of the collected secondary electron signals. If the probe current is selected such that the yield of secondary electrons is greater than 1, the processing system (e.g., the image processing system 590) may calculate the corresponding voltage difference and current of the sample 550 and then determine the electrical properties of the sample 550, as described above for Figure 4 As stated.

[0053] Now refer to Figure 6 , Figure 6 is a diagram showing a charged particle beam device (such as Figure 5 Schematic diagram of various scan lines of the primary electron beam across the sample surface applied by a charged particle beam device (as shown). Figure 6 A top view of a sample field of view 601 is shown, wherein the primary electron beam is scanned as a scan line across the field of view 601 for a time interval. A deflector, e.g. Figure 5 The deflectors 553a-553e in the embodiment can deflect the focused primary electron beam. Figure 6, the time intervals of the first scan line 610, the second scan line 611, and the third scan line 612 can each be 10μs to 100μs, inclusive. In some embodiments, the primary electron beam is adjusted to have a first probe current and scan the first scan line 610 for a first time interval. Before scanning, the electron beam can be focused by an objective lens, which can be communicatively coupled with a processor to apply and record an electrical signal, thereby generating a magnetic field to focus the electron beam at the first probe current value. After completing the first scan line 610, the probe current of the primary electron beam can be adjusted, and the primary electron beam can be focus compensated by a deflector as described above. The refocused primary electrons can be repositioned to a different position, as shown by trace 610_1, where the primary electron beam can then be rescanned across the sample at a different probe current, as shown by scan line 611. Similarly, as shown by scan line 612, the probe current of the primary electron beam can be adjusted and scanned a third time. It should be understood that Figure 6 is for illustrative purposes, and the width, length, and number of scan lines 610, 611, and 612 are not limited thereto. It will also be appreciated that multiple lines may be scanned across the sample at the first probe current before adjusting to the second probe current. Each probe current may be selected such that the yield of secondary electrons is greater than 1. During each time interval, secondary electrons are emitted and collected by the corresponding detector to generate a corresponding image for each scan line. The image processing system may be as described above in Figure 4 The corresponding electrical properties of the sample field of view 601 are calculated in reverse as discussed in . Thus, the charged particle beam device is used as a non-contact probe to determine the electrical properties of the sample field of view 601 .

[0054] Now refer to Figure 7 , Figure 7 is a schematic diagram of the top of a charged particle beam apparatus with an astigmatism corrector according to an embodiment of the present disclosure. The astigmatism corrector can be configured to apply a weak electric field or magnetic field to the primary electron beam to reduce the astigmatism of the primary electron beam. In some embodiments, instead of a converging lens, an astigmatism corrector can be used to apply a focusing effect to the primary electron beam to change the probe current of the primary electron beam. In some embodiments, the astigmatism corrector 727 can include a plurality of electrodes. The astigmatism corrector 727 can be communicatively coupled to the controller 109, wherein an electrical signal is applied to the astigmatism corrector 727, as described above with respect to Figure 5 As discussed above with respect to the converging lens 526 in FIG. The astigmatism corrector 727 can generate a corresponding electrostatic field 727_a that can exert a focusing effect to steer the primary electron beam 705. In some embodiments, when the astigmatism corrector 727 can be configured as an electrostatic lens, the focusing effect of the converging lens 726 can remain constant. Although Figure 7The specific focusing effect of the converging lens 726 is shown, but it will be appreciated that the converging lens 726 may exert any focusing effect on the primary electron beam 705, but will remain constant while the probe current may be varied by the astigmatism corrector 727. Figure 7 Further shown is an astigmatism corrector 727 that applies a focusing effect to focus the primary electron beam 705, but it should be understood that the astigmatism corrector 727 can apply any focusing effect to steer the primary electron beam 705 to adjust the probe current. In some embodiments, a subset of the deflectors (such as Figure 5 533d or 533e or both) can be used as an electrostatic lens in combination with the astigmatism corrector 727 to compensate for the focusing of the primary electron beam 705 when the probe current varies.

[0055] Now refer to Figure 8 , which is a flow chart showing an exemplary process for compensating electron beam focusing according to an embodiment of the present disclosure. The steps of method 800 may be performed by a charged particle beam device such as a SEM, for example, as described above with reference to Figure 5 、 Figure 6 and Figure 7 As described, in a computing device (e.g., Figure 1 The method 800 may be executed on a controller 109 of the computer system or using features of a computing device. It should be understood that the illustrated method 800 may be altered to modify the order of steps and include additional steps.

[0056] Method 800 is a process for determining the electrical properties of a sample device using a primary charged particle beam (such as a SEM) without direct contact with the sample. The sample device can be scanned multiple times with the primary charged particle beam at different probe currents or landing energies. As a result of changing the probe current, the primary charged particle beam may be overfocused or underfocused. Using a magnetic objective lens to adjust the focus can reduce throughput, so the primary charged particle beam can be compensated for focus with additional components of a charged particle beam apparatus (such as a SEM). Images generated by secondary charged particles emitted by the primary charged particle beam at different probe currents or landing energies can be used to reversely calculate the electrical properties of the sample device.

[0057] In step S801, the first lens can manipulate the charged particle source (such as Figure 5 The primary charged particle beam (such as the cathode 503 in Figure 5 In some embodiments, the first probe current can be selected so that the yield of the emitted secondary charged particles is greater than 1 (such as Figure 3In some embodiments, the first lens can manipulate the primary charged particle beam by applying a focusing effect to the primary charged particle beam to achieve a first probe current. In some embodiments, the first lens is coupled to a controller (such as Figure 1 109) in communication with the controller 109 in the embodiment of the present invention, wherein an electrical signal is applied to the first lens to steer the primary charged particle beam. In some embodiments, the first lens can be as described above with respect to Figure 5 In some embodiments, the converging lens can be a magnetic, electrostatic, or composite magnetic and electrostatic lens. In some embodiments, the first lens can be a lens as described above with reference to Figure 7 The astigmatism corrector lens. In some embodiments, the astigmatism corrector lens can be an electrostatic lens.

[0058] In step S802, an objective lens (eg Figure 5 The objective lens 532 in FIG. 5 focuses the primary charged particle beam at the first probe current onto a surface substantially on the sample (e.g. Figure 5 In some embodiments, the objective lens can be communicatively coupled to a processor that can 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 can record the intensity of the electrical signal applied to the objective lens.

[0059] In step S803, the primary charged particle beam at the first probe current may be deflected by a deflector (such as Figure 5 The deflectors 533a-533e in the image processing apparatus are deflected to scan the first scan line across the field of view of the sample surface for a time interval. In some embodiments, the time interval can be 10 μs to 100 μs, inclusive, as described above with respect to Figure 6 As explained. In some embodiments, a primary charged particle beam at a first probe current can be scanned across the surface of a sample using a deflector. In some embodiments, the primary charged particle beam at the first probe current can be scanned across a line on the sample. In some embodiments, the primary charged particle beam at the first probe current can be scanned across multiple lines on the sample. The primary charged particle beam scanned across the sample at the first probe current can result in a sample charge difference (such as Figure 4 The sample voltage difference 420 in the sample generates a sample current (eg Figure 4 Sample current 410 in).

[0060] In step S804, after scanning the first scan line, the setting of the first lens can be changed to manipulate the primary charged particle beam to obtain a second probe current of the primary charged particle beam. The second probe current can be different from the first probe current. The first lens can manipulate the primary charged particle beam to achieve the second probe current as described above. The second probe current can be selected so that the yield of the emitted secondary charged particles is greater than 1. This can result in different surfaces of the sample and produce different sample voltage differences (such as Figure 4 The sample voltage difference 420 in Figure 4 Sample current 410 in).

[0061] In step S805, without changing the objective lens (eg Figure 5 In the case of an objective lens 532 in the embodiment of the present invention, a second lens can be used to compensate for the focus change of the primary charged particle beam at the second probe current. As described above, increasing or decreasing the probe current can cause focus changes (e.g., overfocusing or underfocusing). Figure 5 As explained, deflector (e.g., deflector 533d) can be used for compensation. Similarly, one or more deflectors (e.g., deflectors 533d and 533e) can be used for compensation. During this step, the identical electrical signal applied by the processor in step S803 can be applied to the object lens, because the setting of the adjustment object lens may take a long time to compare. In certain embodiments, the second lens can be one or more deflectors, and each deflector comprises a plurality of electrodes used alone or in combination. In certain embodiments, the second lens can be an electrostatic lens. In certain embodiments, the second lens can be coupled with the processor communication ground, and wherein the electrical signal can be applied to all electrodes in the plurality of electrodes comprising the deflector. In certain embodiments, the identical electrical signal can be applied to all electrodes in the plurality of electrodes comprising the deflector. In certain embodiments, the focusing function of the deflector can not interfere with the deflection function of the deflector.

[0062] In step S806, the primary charged particle beam at the second probe current may be deflected by a deflector (eg Figure 5 The primary charged particle beam at the second probe current can be scanned across the sample as described in the embodiment referenced in step S803 above. The primary charged particle beam scanned across the sample at the second probe current can result in different surface charges of the sample and produce different sample currents.

[0063] Now refer to Figure 9 , Figure 9is a flow chart showing an exemplary process for determining electrical properties of a sample without direct contact according to an embodiment of the present disclosure. The steps of method 900 may be performed by a charged particle beam device such as a SEM, for example, as described above with reference to Figure 5 、 Figure 6 and Figure 7 As described, in a computing device (e.g., Figure 1 The method 900 is executed on a controller 109 of the computer system or is otherwise executed using features of a computing device. It should be understood that the illustrated method 900 can be changed to modify the order of the steps and include additional steps.

[0064] In step S901, a primary charged particle beam of a first probe current may be scanned across a field of view on a sample surface for a first scan line for a time interval. Prior to scanning, the primary charged particle beam may have been manipulated to achieve the first probe current (e.g., according to Figure 8 step S801) and compensate for focus changes (e.g., according to Figure 8 The primary charged particle beam at the first probe current may be as described in the embodiments detailed above (e.g., according to the above description of Figure 6 Description of ) across the sample scan.

[0065] In step S902, a detector may collect a first detection data set from secondary charged particles emitted in response to the primary charged particle beam at a first probe current striking the sample on the first scan line. In some embodiments, the first detection data set may include the current of the secondary charged particles emitted in response to the primary charged particle beam at the first probe current striking the sample on 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 for generating a voltage difference (such as Figure 4 The accumulated surface charge of the sample voltage difference 420 in the sample, and the sample current (e.g. Figure 4 Sample current 410 in).

[0066] At step S903, the primary charged particle beam at the second probe current may be scanned across the field of view on the sample surface in a second scan line for a time interval. Prior to scanning, the primary charged particle beam may have been manipulated to achieve the second probe current (e.g., according to Figure 8 step S804) and compensate for focus changes (e.g., according to Figure 8 The primary charged particle beam at the second probe current may be as described in the embodiments detailed above (e.g., according to the above description of Figure 6 Description of ) is scanned on the sample.

[0067] 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 on the second scan line. In some embodiments, the second detection data set may include the current of the secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample on 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 for generating a voltage difference (e.g., Figure 4 The accumulated surface charge of the sample voltage difference 420 in the sample, and the sample current (e.g. Figure 4 Sample current 410 in).

[0068] At step S905, an electrical characteristic of a 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 (eg, resistance or capacitance).

[0069] A non-transitory computer readable medium may be provided that may store information for use with a controller (e.g., Figure 1 The controller 109) executes the instructions of the processor to perform inspection image acquisition, workbench positioning, primary charged particle beam focusing and compensation, inspection of electrical characteristics of the sampling device, electrostatic field adjustment, objective lens adjustment, activation of the charged particle source, Figure 8 Method 800, Figure 9 The present invention relates to a method 900 for a charged particle system and other executable functions related to primary charged particle beam focus compensation and non-contact nanoprobe methods. Common forms of non-transitory media include, for example, floppy disks, flexible disks, hard disks, solid-state drives, magnetic tapes or any other magnetic data storage media, compact disk read-only memories (CD-ROMs), any other optical data storage media, any physical media with a pattern of holes, random access memories (RAMs), programmable read-only memories (PROMs) and erasable programmable read-only memories (EPROMs), FLASH-EPROMs or any other flash memories, non-volatile random access memories (NVRAMs), cache memories, registers, any other memory chips or storage boxes, and networked versions thereof.

[0070] These embodiments can be further described using the following terms:

[0071] 1. A charged particle beam apparatus for examining a sample, comprising:

[0072] a charged particle source configured to emit a primary charged particle beam;

[0073] a first lens configured to steer the primary charged particle beam to adjust a probe current of the primary charged particle beam;

[0074] an objective lens configured to focus the primary charged particle beam to a focal point substantially on the surface of the sample;

[0075] a second lens configured to generate an electrostatic field that substantially overlaps the magnetic field generated by the objective lens and also to compensate for focus changes caused by changes in probe current caused by the first lens without changing the optical power of the objective lens; and

[0076] A deflector is configured to deflect the primary charged particle beam to scan a scan line of a field of view of the sample.

[0077] 2. The device of clause 1, wherein the first lens is a magnetic lens.

[0078] 3. The device of clause 1 , wherein the first lens is an electrostatic lens.

[0079] 4. The device of clause 1 , wherein the first lens is a composite magnetic and electrostatic lens.

[0080] 5. A device according to clause 3 or 4, wherein the first lens comprises a plurality of electrodes.

[0081] 6. The device of clause 5, wherein an electrical signal is applied to the plurality of electrodes.

[0082] 7. The device of any of clauses 1-4, wherein the first lens is a converging lens.

[0083] 8. The device of any of clauses 1-4, wherein the first lens is an astigmatism corrector.

[0084] 9. The device of clause 1 , wherein the second lens is an electrostatic lens.

[0085] 10. The device of clause 9, wherein the second lens comprises a plurality of electrodes.

[0086] 11. The device of clause 10, wherein an electrical signal is applied to the plurality of electrodes.

[0087] 12. The apparatus of clause 11, wherein the same electrical signal is applied to all electrodes of the plurality of electrodes.

[0088] 13. The device of clause 1, wherein the second lens is a deflector.

[0089] 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.

[0090] 15. The apparatus of clause 14, wherein the charged particle detector comprises circuitry configured to determine electrical characteristics of the sample based on the collected charged particle data without direct contact with the sample.

[0091] 16. A charged particle beam apparatus for examining a sample, comprising:

[0092] a charged particle source configured to emit a primary charged particle beam;

[0093] a first lens configured to steer the primary charged particle beam to adjust a probe current level of the primary charged particle beam;

[0094] an objective lens configured to focus the primary charged particle beam to a focal point substantially on the surface of the sample; and

[0095] a plurality of deflectors configured to deflect the primary charged particle beam to scan scan lines of the field of view of the sample, wherein a subset of the plurality of deflectors is further configured to generate an electrostatic field that substantially overlaps with the magnetic field generated by the objective lens and further compensates for focus changes caused by changes in probe current levels, wherein changes in the probe current levels are caused by the first lens.

[0096] 17. The device of clause 16, wherein the first lens is a magnetic lens.

[0097] 18. The device of clause 16, wherein the first lens is an electrostatic lens.

[0098] 19. The device of clause 16, wherein the first lens is a composite magnetic and electrostatic lens.

[0099] 20. The device of clause 18 or 19, wherein the first lens comprises a plurality of electrodes.

[0100] 21. The device of clause 20, wherein an electrical signal is applied to the plurality of electrodes.

[0101] 22. The device of any of clauses 16-19, wherein the first lens is a converging lens.

[0102] 23. The device of any of clauses 16-19, wherein the first lens is an astigmatism corrector.

[0103] 24. The apparatus of clause 16, wherein the subset of the plurality of deflectors is an electrostatic lens.

[0104] 25. An apparatus according to clause 24, wherein each deflector in the subset of the plurality of deflectors comprises a plurality of electrodes.

[0105] 26. The device of clause 25, wherein an electrical signal is applied to the plurality of electrodes.

[0106] 27. The device of clause 26, wherein the same electrical signal is applied to all electrodes of the plurality of electrodes.

[0107] 28. A method of adjusting the focus of a charged particle beam to examine a sample, comprising:

[0108] manipulating a primary charged particle beam emitted by a charged particle source with a first lens to change a current of the primary charged particle beam into a first probe current;

[0109] focusing the primary charged particle beam at the first probe current to a focal point substantially at the surface of the sample with an objective lens;

[0110] scanning a first scan line of a field of view of the sample with the primary charged particle beam at the first probe current;

[0111] After scanning the first scan line, steering the primary charged particle beam with the first lens to change the current of the primary charged particle beam to a second probe current;

[0112] compensating for focus variations of the primary charged particle beam at the second probe current using a second lens without changing the setting of the objective lens; and

[0113] A second scan line of the field of view of the sample is scanned 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.

[0114] 29. The method of clause 28, wherein the first lens is a magnetic lens.

[0115] 30. The method of clause 28, wherein the first lens is an electrostatic lens.

[0116] 31. The method of clause 28, wherein the first lens is a composite magnetic and electrostatic lens.

[0117] 32. The method of clause 30 or 31, wherein the first lens comprises a plurality of electrodes.

[0118] 33. The method of clause 32, further comprising applying an electrical signal to the plurality of electrodes.

[0119] 34. The method according to any of clauses 28-31, wherein the first lens is a converging lens.

[0120] 35. The method according to any of clauses 28-31, wherein the first lens is an astigmatism corrector.

[0121] 36. The method of clause 28, wherein the second lens is an electrostatic lens.

[0122] 37. The method of clause 36, wherein the second lens comprises a plurality of electrodes.

[0123] 38. The method of clause 37, further comprising applying an electrical signal to the plurality of electrodes.

[0124] 39. The method of clause 38, further comprising applying the same electrical signal to all electrodes in the plurality of electrodes.

[0125] 40. The method of clause 28, wherein the second lens is a deflector.

[0126] 41. The method according to clause 28, further comprising:

[0127] 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; and

[0128] Charged particle detection data is collected from secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample.

[0129] 42. The method of clause 41, further comprising determining an electrical characteristic of the sample based on the charged particle detection data from the primary charged particle beam at the first probe current and the primary charged particle beam at the second probe current impinging on the sample.

[0130] 43. The method of clause 28, wherein the scanning of the first line and the scanning of the second line are performed sequentially without intervening scanning of any other line occurring.

[0131] 44. A method of examining a sample using a charged particle beam apparatus, the charged particle beam apparatus being configured to direct a charged particle beam onto the sample, the method comprising:

[0132] scanning a first scan line of a field of view of the sample with the charged particle beam at a first probe current;

[0133] collecting a first detection data set from secondary charged particles emitted in response to the charged particle beam impinging on the sample on the first scan line;

[0134] scanning a second scan line of a field of view of the sample with the charged particle beam at a second probe current, wherein scanning the first scan line and scanning the second scan line are performed sequentially;

[0135] collecting a second detection data set from secondary charged particles emitted in response to the charged particle beam impinging on the sample on the second scan line; and

[0136] A current-voltage characteristic of a portion of the sample is determined based on the first detection data set and the second detection data set.

[0137] 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 intervening scanning of any other line occurring.

[0138] 46. The method of clause 44, wherein the current-voltage characteristic is the resistance or capacitance of the sample.

[0139] 47. The method of clause 44, further comprising identifying a sample defect by comparing the current-voltage characteristic to an expected current-voltage characteristic for the portion of the sample.

[0140] 48. A non-transitory computer-readable medium storing a set of instructions executable by one or more processors of a charged particle beam apparatus to cause the charged particle beam apparatus to perform a method of examining a sample, the method comprising:

[0141] manipulating a primary charged particle beam emitted by a charged particle source with a first lens to change a current of the primary charged particle beam into a first probe current;

[0142] focusing the primary charged particle beam at a first probe current to a focal point substantially at the surface of the sample with an objective lens;

[0143] scanning a first scan line of a field of view of the sample with the primary charged particle beam at the first probe current;

[0144] After scanning the first scan line, steering the primary charged particle beam with the first lens to change the current of the primary charged particle beam to a second probe current;

[0145] compensating for focus variations of the primary charged particle beam at the second probe current using a second lens without changing the setting of the objective lens; and

[0146] A second scan line of the field of view of the sample is scanned 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.

[0147] 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 intervening scanning of any other line occurring.

[0148] 50. The non-transitory computer-readable medium of clause 48, wherein the first lens is a magnetic lens.

[0149] 51. The non-transitory computer-readable medium of clause 48, wherein the first lens is an electrostatic lens.

[0150] 52. The non-transitory computer-readable medium of clause 48, wherein the first lens is a composite magnetic and electrostatic lens.

[0151] 53. The non-transitory computer-readable medium of clause 51 or 52, wherein the first lens comprises a plurality of electrodes.

[0152] 54. The non-transitory computer-readable medium of clause 53, wherein an electrical signal is applied to the plurality of electrodes.

[0153] 55. The non-transitory computer-readable medium of any of clauses 48-52, wherein the first lens is a converging lens.

[0154] 56. The non-transitory computer-readable medium of any of clauses 48-52, wherein the first lens is an astigmatism corrector.

[0155] 57. The non-transitory computer-readable medium of clause 48, wherein the second lens is an electrostatic lens.

[0156] 58. The non-transitory computer-readable medium of clause 57, wherein the second lens comprises a plurality of electrodes.

[0157] 59. The non-transitory computer-readable medium of clause 58, wherein an electrical signal is applied to the plurality of electrodes.

[0158] 60. The non-transitory computer-readable medium of clause 59, wherein the same electrical signal is applied to all electrodes of the plurality of electrodes.

[0159] 61. The non-transitory computer-readable medium of clause 48, wherein the second lens is a deflector.

[0160] 62. The non-transitory computer-readable medium of clause 48, wherein the set of instructions is executable by the one or more processors to cause the charged particle beam apparatus to further perform:

[0161] 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; and

[0162] Charged particle detection data is collected from secondary charged particles emitted in response to the primary charged particle beam at the second probe current striking the sample.

[0163] 63. A non-transitory computer-readable medium according to claim 62, wherein the instruction set is capable of being executed by the one or more processors to cause the charged particle beam device to further perform the following operations: determine the electrical characteristics of the sample based on the charged particle detection data from the primary charged particle beam at the first probe current and at the second probe current impacting the sample.

[0164] It should be understood that the embodiments of the present invention are not limited to the exact configurations described above and illustrated in the accompanying drawings, and that various modifications and changes may be made without departing from the scope of the present invention. The present disclosure has been described in conjunction with various embodiments, and other embodiments of the present invention will be apparent to those skilled in the art by consideration of the specification and practice of the invention disclosed herein. The description and examples are intended to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the appended claims.

Claims

1. A charged particle beam apparatus for examining a sample, 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 the magnetic field generated by the objective lens and also to compensate for focus changes caused by changes in probe current caused by the first lens without changing the optical power of the objective lens; as well as A deflector is configured to deflect the primary charged particle beam to scan a scan line of a field of view of the sample. The device according to claim 1 , wherein the first lens is a magnetic lens. The device of claim 1 , wherein the first lens is an electrostatic lens.

4. The apparatus of claim 1, wherein the first lens is a composite magnetic and electrostatic lens. The device of claim 3 , wherein the first lens comprises a plurality of electrodes. The device according to claim 5 , wherein an electrical signal is applied to the plurality of electrodes. The device of claim 1 , wherein the first lens is a converging lens.

8. The apparatus of claim 1, wherein the first lens is an astigmatism corrector.

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

10. The device of claim 9, wherein the second lens comprises a plurality of electrodes. The device according to 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 electrodes of the plurality of electrodes.

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

14. The apparatus according to claim 1 further comprises a charged particle detector configured to collect charged particle data from secondary charged particles emitted in response to the primary charged particle beam impacting the sample, wherein the charged particle detector comprises a circuit system configured to determine electrical properties of the sample based on the collected charged particle data without direct contact with the sample.

15. A non-transitory computer-readable medium storing an instruction set, wherein the instruction set is executable by one or more processors of a charged particle beam device to cause the charged particle beam device to perform a method for examining a sample, the method comprising: manipulating a primary charged particle beam emitted by a charged particle source with a first lens to change a 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 with 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 with the first lens to change the current of the primary charged particle beam to a second probe current; compensating for focus variations of the primary charged particle beam at the second probe current using a second lens without changing the setting of the objective lens; as well as A second scan line of the field of view of the sample is scanned 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.

Images