scanning electron microscope, scanning electron microscopy, sem, scanning electron micro

Abstract

The application discloses a scanning electron microscope, and belongs to the technical field of semiconductor detection. The scanning electron microscope comprises an electron beam source configured to emit an electron beam; an objective lens configured to focus the electron beam onto a sample; the objective lens comprises a first magnetic circuit assembly and a second magnetic circuit assembly, and a gap is formed between the first magnetic circuit assembly and the second magnetic circuit assembly; at least one set of detection assemblies configured to detect signals generated by interaction between the electron beam and the sample, wherein the detection assemblies are arranged in the gap; each set of the at least one set of detection assemblies comprises a first detection unit and a second detection unit, each first detection unit is arranged on a transmission path of a backscattered electron signal and configured to detect the backscattered electron signal, and each second detection unit is arranged on a transmission path of a secondary electron signal and configured to detect the secondary electron signal. The application takes the gap as a detection area, and can separately detect the backscattered electron signal and the secondary electron signal.

Description

Technical Field

[0001] This invention relates to the field of semiconductor detection technology, and more specifically to a scanning electron microscope. Background Technology

[0002] Scanning electron microscopy (SEM) excites various electronic signals, such as secondary electrons (SE) and backscattered electrons (BSE), by bombarding the sample with an electron beam. These signals are then acquired and processed by detectors to enable morphological imaging and compositional analysis of the sample. Accurate detection of the secondary and backscattered electron signals is crucial for ensuring imaging resolution and improving the accuracy of compositional analysis. However, current SEMs often place detectors on the outer edge of the pole piece or below the sample, leading to signal mixing and hindering efficient separation of the secondary and backscattered electron signals. Summary of the Invention

[0003] To address the problems existing in the prior art, this application provides a scanning electron microscope that, by using the gap between the first magnetic circuit assembly and the second magnetic circuit assembly as the detection area, enables more comprehensive and accurate detection of backscattered electron signals and secondary electron signals. Furthermore, by using the first and second detection units to separately detect the backscattered electron signals and secondary electron signals, the problem of signal mixing is improved. The technical solution is as follows:

[0004] A scanning electron microscope, comprising:

[0005] An electron beam source is used to emit an electron beam.

[0006] An objective lens is used to focus the electron beam onto the sample.

[0007] The objective lens includes a first magnetic circuit assembly and a second magnetic circuit assembly, with a gap formed between the first magnetic circuit assembly and the second magnetic circuit assembly;

[0008] At least one set of detection components is provided for detecting the signal generated by the interaction between the electron beam and the sample, and the detection components are disposed within the gap;

[0009] Each of the at least one set of detection components includes a first detection unit and a second detection unit. Each first detection unit is disposed on the transmission path of the backscattered electron signal and is used to detect the backscattered electron signal. Each second detection unit is disposed on the transmission path of the secondary electron signal and is used to detect the secondary electron signal.

[0010] Optionally, the at least one set of detection components are evenly distributed circumferentially around the central axis of the first magnetic circuit component and the second magnetic circuit component.

[0011] Optionally, each first detection unit is disposed adjacent to the first magnetic circuit component, and the distance between each first detection unit and the first magnetic circuit component is not less than a distance threshold.

[0012] Each second detection unit is disposed adjacent to the second magnetic circuit assembly, and the distance between each second detection unit and the second magnetic circuit assembly is not less than the distance threshold.

[0013] Optionally, the scanning electron microscope further includes:

[0014] A control component is used to perform a first bias voltage determination step for each first detection unit and output a corresponding first bias voltage for each first detection unit;

[0015] The first bias voltage determination step includes:

[0016] The first bias voltage is determined based on the first electric field regulating voltage, the position parameters of the first detection unit, and the objective lens current.

[0017] Optionally, the position parameters of the first detection unit include a first position calibration coefficient, a first position correction coefficient, and a first radial distance corresponding to the first detection unit, wherein the first radial distance is used to indicate the distance between the first detection unit and the central axis.

[0018] Optionally, the control component is further configured to:

[0019] Perform a second bias voltage determination step for each second detection unit, and output a corresponding second bias voltage for each second detection unit;

[0020] The second bias voltage determination step includes:

[0021] The second bias voltage is determined based on the second electric field regulating voltage, the position parameters of the second detection unit, and the objective lens current.

[0022] Optionally, the position parameters of the second detection unit include a second position calibration coefficient, a second position correction coefficient, a second radial distance, a detection unit height, and a sample axial height, wherein the detection unit height is used to indicate the distance between the second detection unit and the sample, and the sample axial height is used to indicate the distance between the second magnetic circuit assembly and the sample.

[0023] Optionally, the at least one set of detection components has at least two detection modes, including a backscattered electron signal main acquisition mode and a secondary electron signal main acquisition mode.

[0024] Optionally, when the at least one set of detection components is in the backscattered electron signal main acquisition mode, the control component is further configured to:

[0025] After performing the first bias voltage determination step for each first detection unit, for each first bias voltage: the first bias voltage is switched to a third bias voltage, the polarity of which is opposite to that of the first bias voltage;

[0026] A corresponding third bias voltage is output for each first detection unit;

[0027] After performing the second bias voltage determination step for each second detection unit, for each second bias voltage: the second bias voltage is switched to a fourth bias voltage, the fourth bias voltage being greater than the second bias voltage;

[0028] A corresponding fourth bias voltage is output for each second detection unit.

[0029] Optionally, when the at least one set of detection components is in the secondary electronic signal main acquisition mode, the control component is further configured to:

[0030] After performing the second bias voltage determination step for each second detection unit, for each second bias voltage: the second bias voltage is switched to a fifth bias voltage, which is greater than the second bias voltage and less than a voltage threshold.

[0031] A corresponding fifth bias voltage is output for each second detection unit;

[0032] After performing the first bias voltage determination step for each first detection unit, for each first bias voltage: determine a sixth bias voltage based on the fifth bias voltage, wherein the absolute value of the sixth bias voltage is less than the fifth bias voltage; switch the first bias voltage to the sixth bias voltage;

[0033] A corresponding sixth bias voltage is output for each first detection unit.

[0034] Optionally, each first detection unit and each second detection unit include a conductive block and a scintillator;

[0035] The conductive block is disposed on the scintillator. The conductive block is used to apply its own voltage to the scintillator to change the degree of attraction of the scintillator to secondary electrons. The voltage of the conductive block is equal to the bias voltage of its corresponding first detection unit or second detection unit.

[0036] The scintillator is also used to convert the detected backscattered electron signal into a first optical signal, or to convert the detected secondary electron signal into a second optical signal.

[0037] Optionally, each first detection unit and each second detection unit further includes an optical signal transmission channel and a photoelectric amplifier;

[0038] The optical signal transmission channel is located after the scintillator and is used to transmit the first optical signal or the second optical signal to the photoelectric amplifier.

[0039] The photoelectric amplifier is used to convert the first optical signal into a first electrical signal, or to convert the second optical signal into a second electrical signal.

[0040] Optionally, the scanning electron microscope further includes:

[0041] A sealing assembly is used to seal the gap so that the detection area of ​​the at least one set of detection components is a vacuum detection zone.

[0042] The technical solution provided in this application can bring at least the following beneficial effects:

[0043] This application, by configuring at least one set of detection components within the gap between the first magnetic circuit component and the second magnetic circuit component, and using this gap as the detection area, enables precise detection of low-angle secondary electron signals and backscattered electron signals. Each set of detection components includes a first detection unit and a second detection unit. The first detection unit is positioned on the transmission path of the backscattered electrons to detect the backscattered electron signal, and the second detection unit is positioned on the transmission path of the secondary electron signal to detect the secondary electron signal. This allows for the separate detection of the secondary electron signal and the backscattered electron signal, achieving efficient separation of the two signals, increasing the quantity and efficiency of signal acquisition, and thus improving image resolution. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of a scanning electron microscope provided in an embodiment of this application;

[0045] Figure 2 A schematic diagram of the paths of backscattered electrons and secondary electrons provided for embodiments of this application;

[0046] Figure 3 A top view of the structure of a scanning electron microscope provided in an embodiment of this application;

[0047] Figure 4 A schematic diagram of the structure of a first detection unit and a second detection unit provided in an embodiment of this application;

[0048] Figure 5 This is a schematic diagram of another scanning electron microscope provided in an embodiment of this application;

[0049] Figure 6 A top view of the structure of another scanning electron microscope provided in this application embodiment;

[0050] Figure 7 This is a schematic diagram of the structure of another scanning electron microscope provided in the embodiments of this application;

[0051] Figure 8 A top view of the structure of another scanning electron microscope provided in the embodiments of this application;

[0052] Figure 9 This is a schematic diagram of the structure of a control component provided in an embodiment of this application. Detailed Implementation

[0053] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0054] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0055] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this invention, unless otherwise specified, include both direct and indirect connections (linkages).

[0056] Before providing a detailed explanation of the scanning electron microscope provided in the embodiments of this application, the application scenarios involved in the embodiments of this application will be introduced first.

[0057] Current scanning electron microscope (SEM) electron detection systems typically place detectors outside the pole pieces, below the sample, or inside the objective lens in the gap region not between the upper and lower pole pieces. Signal collection is usually achieved using a reflector cone, daguerreotype, or a single bias electrode, resulting in poor structural integration. Furthermore, the vacuum gap between the upper and lower pole pieces, being the primary area of ​​motion for secondary and backscattered electron signals at low angles, is not detected. Simultaneously, existing electron microscope detection techniques suffer from signal mixing, making efficient separation of secondary and backscattered electron signals difficult. Some SEMs employ complex electron multiplier tube combinations to improve detection efficiency, but without optimizing the detector's spatial layout by incorporating the rotational symmetry of the upper and lower pole pieces, the spatial coverage of signal acquisition is poor, making it difficult to maximize the collection of low-angle scattered secondary and backscattered electron signals.

[0058] Based on this, embodiments of this application provide a scanning electron microscope that arranges at least one set of detection components in the gap between a first magnetic circuit component and a second magnetic circuit component. This allows for the detection of low-angle secondary electron signals and backscattered electron signals. Each set of detection components includes a first detection unit and a second detection unit. The first detection unit is disposed on the transmission path of the backscattered electrons and is used to detect the backscattered electron signal. The second detection unit is disposed on the transmission path of the secondary electron signal and is used to detect the secondary electron signal. This allows for the separate detection of the secondary electron signal and the backscattered electron signal, achieving efficient separation from the backscattered electron signal.

[0059] The scanning electron microscope provided in the embodiments of this application will now be described in detail.

[0060] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of a scanning electron microscope provided in an embodiment of this application. From... Figure 1 As can be seen from the figure, the scanning electron microscope includes: an electron beam source 1 for emitting an electron beam; an objective lens 2 for focusing the electron beam onto the sample; the objective lens 2 includes a first magnetic circuit assembly 21 and a second magnetic circuit assembly 22, with a gap formed between the first magnetic circuit assembly 21 and the second magnetic circuit assembly 22; and at least one set of detector components 3 (two sets are shown schematically in the figure) for detecting the signal generated by the interaction between the electron beam and the sample. The detector components 3 are disposed within the gap, and each set of detector components 3 includes a first detection unit 31 and a second detection unit 32. Each first detection unit 31 is disposed on the transmission path of the backscattered electron signal for detecting the backscattered electron signal; and each second detection unit 32 is disposed on the transmission path of the secondary electron signal for detecting the secondary electron signal.

[0061] The electron beam source 1 serves as the core emitting component of the scanning electron microscope, used to continuously emit a stable high-energy electron beam. It should be noted that the electron beam source 1 can be a thermally reflective electron beam source, a field emission electron beam source, or other types of electron beam sources; that is, the embodiments of this application do not limit the type of electron beam source 1.

[0062] Objective lens 2 is used to converge and focus the electron beam incident into it, compress the electron beam spot and converge the optical path, modulate the divergent electron beam into a fine focused electron beam, and accurately project it onto the surface of the sample to be tested, thereby reducing the size of the electron beam spot so that subsequent observation and measurement of the sample's micro-morphology, key dimensions, overlay errors and micro-defects can be achieved based on the acquired electronic signals.

[0063] In some embodiments, the scanning electron microscope further includes a beam shaping assembly disposed between the electron beam source 1 and the objective lens 2 for adjusting the electron beam.

[0064] In some embodiments, please refer to Figure 1 The objective lens 2 includes a first magnetic circuit assembly 21 and a second magnetic circuit assembly 22, and the first magnetic circuit assembly 21 and the second magnetic circuit assembly 22 are spaced apart, thereby forming a gap between the first magnetic circuit assembly 21 and the second magnetic circuit assembly 22.

[0065] In some embodiments, the first magnetic circuit assembly 21 includes an upper pole shoe, and the second magnetic circuit assembly 22 includes a lower pole shoe. The upper and lower pole shoes are arranged opposite each other along the electron beam transmission direction, forming a pole shoe gap. The cooperation of the upper and lower pole shoes can converge and constrain the magnetic field lines, so that the magnetic field is concentrated in the pole shoe gap to form an axisymmetric focusing magnetic field. On the one hand, it can converge and focus the incident electron beam, so that it can be accurately projected onto the sample surface. On the other hand, it can constrain the transmission path and guide the optical path of backscattered electrons and secondary electrons emitted from the sample after being excited by the electron beam, so as to facilitate the efficient detection and acquisition of related electronic signals by the subsequent detection assembly 3.

[0066] In some embodiments, the gap is the main motion region of low-angle backscattered electron signals and secondary electrons. The detection component 3 is configured in the gap, which can more accurately and comprehensively acquire and detect backscattered electron signals and secondary electron signals while detecting the signals generated by the interaction between the electron beam and the sample.

[0067] It can be seen that after the electron beam emitted by the electron beam source 1 is focused by the objective lens 2, it can bombard the sample surface and generate low-angle secondary electrons (initial energy about 0~50eV) and backscattered electrons (initial energy about 1~15keV). The two types of electrons will move towards the gap along different low-angle trajectories.

[0068] In some embodiments, each group of detection components 3 includes a first detection unit 31 and a second detection unit 32. The first detection unit 31 is positioned on the transmission path of the backscattered electron signal, while the second detection unit 32 is positioned on the transmission path of the secondary electron signal, such as... Figure 2 As shown, this enables the first detection unit 31 to better acquire backscattered electron signals and the second detection unit 32 to better acquire secondary electron signals, effectively improving the problem of signal mixing and thus enhancing the subsequent imaging resolution and the accuracy of component analysis.

[0069] In some embodiments, at least one set of detection components 3 are uniformly distributed circumferentially around the central axis of the first magnetic circuit component 21 and the second magnetic circuit component 22. For example, please refer to... Figure 3 ,from Figure 3 As can be seen, the scanning electron microscope includes four sets of detector components 3, which are evenly distributed in a ring along the central axis at 360°. The included angle between each set is 90 degrees, which ensures the globality of signal acquisition and balances acquisition efficiency with structural complexity.

[0070] It should be noted that the above description is based on the scanning electron microscope comprising four sets of detector components 3. Alternatively, depending on the actual situation, the scanning electron microscope may include more or fewer detector components 3. For example, it may include one set of detector components 3 to reduce costs; or two or three sets of detector components 3 to meet basic detection requirements; or six or eight sets of detector components 3 to improve signal acquisition efficiency. When two sets of detector components 3 are included, the included angle between each set can be 180°; when three sets of detector components 3 are included, the included angle between each set can be 120°; when six sets of detector components 3 are included, the included angle between each set can be 60°; similarly, when eight sets of detector components 3 are included, the included angle between each set can be 40°. Alternatively, the included angle between each set of detector components 3 can be adjusted according to the actual situation so that the detector components 3 are not uniformly distributed. In other words, the embodiments of this application do not limit the number of detector components 3 or the included angle between each set of detector components 3.

[0071] In some embodiments, please refer to Figure 2 Each first detection unit 31 is disposed adjacent to the first magnetic circuit component 21, and the distance between each first detection unit 31 and the first magnetic circuit component 21 is not less than a distance threshold; each second detection unit 32 is disposed adjacent to the second magnetic circuit component 22, and the distance between each second detection unit 32 and the second magnetic circuit component 22 is not less than a distance threshold.

[0072] To better acquire backscattered electron signals, the first detection unit 31 should be positioned on the transmission path of the backscattered electron signal, and each first detection unit 31 should be close to the first magnetic circuit assembly 21. For example, the overall mounting height of the first detection unit 31 can be close to the lower surface of the upper pole shoe, so that the signal receiving surface of the first detection unit 31 enters the original trajectory of the backscattered electron signal in the gap between the upper and lower pole shoes; the overall mounting height of the second detection unit 32 can be close to the lower surface of the lower pole shoe, so that the signal receiving surface of the second detection unit 32 enters the original trajectory of the secondary electron signal in the gap between the upper and lower pole shoes, effectively improving the problem of signal mixing.

[0073] In some embodiments, in order to maintain a corresponding withstand voltage between the first detection unit 31 and the first magnetic circuit assembly 21, the distance between the first detection unit 31 and the first magnetic circuit assembly 21 must be no less than a distance threshold. Similarly, the distance between the second detection unit 32 and the second magnetic circuit assembly 22 must also be no less than a distance threshold. For example, the distance between the first detection unit 31 and the upper pole shoe needs to be no less than 2 mm, and the distance between the second detection unit 32 and the lower pole shoe can also be no less than 2 mm.

[0074] It should be noted that the above example uses a distance threshold of 2mm. In practice, the distance threshold can be any other value. The distance thresholds corresponding to the first detection unit 31 and the first magnetic circuit assembly 21, and the distance thresholds corresponding to the second detection unit 32 and the second magnetic circuit assembly 22, can be determined based on actual conditions. The two distance thresholds can be the same or different. This application does not limit this aspect.

[0075] In some embodiments, the distance between each detection unit also needs to be no less than a detection unit distance threshold, and each detection unit needs to maintain a withstand voltage no less than a voltage threshold. For example, the distance between the detection units is no less than 2 mm, and each detection unit has a withstand voltage of no less than 10 kV.

[0076] In some embodiments, the spacing between each first detection unit 31 and its corresponding second detection unit is matched with the gap height. As an example, in order to accommodate the pole piece gaps of different models of scanning electron microscopes, the spacing between the first detection unit 31 and its corresponding second detection unit can be 10mm to 30mm.

[0077] In some embodiments, please refer to Figure 2The signal receiving surface of the first detection unit 31 can be at a low angle to the main axis of the electron beam, such as 0° to 45°, so as to face the trajectory of the backscattered electron signal at a low angle. Similarly, the signal receiving surface of the second detection unit 32 can also be at a low angle to the main axis of the electron beam, such as 0° to 45°, so as to face the trajectory of the secondary electron signal at a low angle.

[0078] In some embodiments, please refer to Figure 4 Each first detection unit 31 and each second detection unit 32 includes a conductive block 311 and a scintillator 312. The conductive block 311 is disposed on the scintillator 312 and is used to apply its own voltage to the scintillator 312 to change the degree of attraction of the scintillator 312 to secondary electrons. The voltage of the conductive block 311 is equal to the bias voltage of its corresponding first detection unit 31 or second detection unit 32. The scintillator 312 is also used to convert the detected backscattered electron signal into a first optical signal or convert the detected secondary electron signal into a second optical signal.

[0079] The conductive block 311 can be a high-voltage metal sheet, and the conductive block 311 is disposed on the scintillator 312. For example, the high-voltage metal sheet can be seamlessly and directly connected to the edge of the scintillator 312.

[0080] In some embodiments, the scintillator 312 can be a scintillator 312 on a conductive glass substrate, wherein the conductive glass substrate can be ITO conductive glass, the scintillator 312 can be a YAG:Ce (cerium-doped yttrium aluminum garnet) scintillator 312, the thickness can be 0.5~1mm, the effective receiving area is 10~20mm², and it has high mechanical strength, vacuum resistance, moderate fluorescence yield, and fast response speed.

[0081] It should be noted that the above description refers to scintillator 312 as a YAG:Ce scintillator 312. Alternatively, in applications, scintillator 312 can also be a CsI(Tl) (cesium iodide-doped thallium) scintillator 312, which has high fluorescence yield and higher sensitivity to low-energy electrons, making it suitable for secondary electron signal acquisition; it can also be a ZnS(Ag) (zinc sulfide-doped silver) scintillator 312, which has a fast response speed to electrons, making it suitable for high-speed scanning dynamic detection; or it can be other scintillators 312. This application does not limit the specific type of scintillator 312 described herein.

[0082] In some embodiments, when a bias voltage is applied to the first detection unit 31, the conductive block 311 on the first detection unit 31 will also have a voltage equal to the bias voltage. The conductive block 311 can conduct its own voltage to the corresponding scintillator 312, thereby changing the attraction degree of the scintillator 312 to secondary electrons, such as negative attraction to secondary electrons, that is, repulsion of secondary electrons, thereby causing the first detection unit 31 to repel secondary electrons, so that the first detection unit 31 can detect backscattered electron signals more accurately.

[0083] When a bias voltage is applied to the second detection unit 32, the conductive block 311 on the second detection unit 32 will also have a voltage equal to the bias voltage. The conductive block 311 can conduct its own voltage to the corresponding scintillator 312, thereby changing the degree of attraction of the scintillator 312 to secondary electrons. For example, it can have a positive attraction effect on secondary electrons, thereby enabling the second detection unit 32 to attract secondary electrons, so that the second detection unit 32 can detect secondary electron signals more accurately.

[0084] Continuing the description above, the scintillator 312, upon receiving backscattered electrons or secondary electrons, can respond to electron excitation and generate a photoelectric conversion effect. Specifically, when the scintillator 312 is the scintillator 312 on the first detection unit 31, it can convert the incident backscattered electron signal into a corresponding first optical signal; when the scintillator 312 is the scintillator 312 on the second detection unit 32, it can convert the incident secondary electron signal into a corresponding second optical signal. This allows for subsequent morphological imaging and compositional analysis of the sample based on the first and / or second optical signals.

[0085] In some embodiments, please refer to Figure 4 Each first detection unit 31 and each second detection unit 32 further includes an optical signal transmission channel 313 and a photoelectric amplifier 314; the optical signal transmission channel 313 is disposed after the scintillator 312 and is used to transmit the first optical signal or the second optical signal to the photoelectric amplifier 314; the photoelectric amplifier 314 is used to convert the first optical signal into a first electrical signal, or to convert the second optical signal into a second electrical signal.

[0086] As described above, the scintillator 312 can convert backscattered electron signals into a first optical signal and secondary electron signals into a second optical signal. Since the optical signal transmission channel 313 is positioned after the scintillator 312, when the optical signal transmission channel 313 serves as the transmission channel for the first detection unit 31, it can transmit the first optical signal; when the optical signal transmission channel 313 serves as the transmission channel for the second detection unit 32, it can transmit the second optical signal.

[0087] In some embodiments, the optical signal transmission channel 313 can be a glass light guide tube. The glass light guide tube is made of high-transmittance quartz glass, and its front end can be closely attached to the scintillator 312, and its rear end can be seamlessly attached to the photoelectric amplifier 314. There is no intermediate transition structure between the scintillator 312 and the photoelectric amplifier 314, which can ensure the transmission efficiency of the first optical signal or the second optical signal.

[0088] In some embodiments, the glass light guide tube can be made of quartz glass, with a diameter of 3mm to 5mm and a light transmittance of ≥98%.

[0089] In some embodiments, please refer to Figure 5 The scanning electron microscope also includes a sealing component 4 (black part in the figure) for sealing the gap so that the detection area of ​​at least one set of detection components 3 is a vacuum detection area.

[0090] Additionally, in some embodiments, the sealing assembly 4 may include a sealing structure and a sealing ring.

[0091] The sealing structure can be made of non-magnetic, high-strength insulating materials, such as ceramics or polytetrafluoroethylene, and can be seamlessly fitted to the inner walls of the first magnetic circuit assembly 21 (i.e., the upper pole shoe) and the second magnetic circuit assembly 22 (i.e., the lower pole shoe) to seal the gap into an independent vacuum detection area, thereby avoiding the loss of electronic signals due to collisions with air molecules during the movement.

[0092] The sealing rings include a radial sealing ring between the first magnetic circuit assembly 21 and the second magnetic circuit assembly 22 and the sealing structure, and a lateral O-ring between the optical signal transmission channel 313 and the sealing structure. The sealing rings can be made of vacuum-resistant and high / low temperature-resistant fluororubber material to ensure the vacuum level of the vacuum detection zone (≤10). - ³Pa).

[0093] Continuing the description above, when the photoelectric amplifier 314 is the photoelectric amplifier 314 of the first detection unit 31, it can receive the first optical signal and convert the first optical signal carrying backscattered electronic information into a first electrical signal; when the photoelectric amplifier 314 is the photoelectric amplifier 314 of the second detection unit 32, it can receive the second optical signal and convert the second optical signal carrying backscattered electronic information into a second electrical signal.

[0094] In some embodiments, the photoelectric amplifier 314 includes a PMT (Photomultiplier Tube), which can convert a first optical signal into a first electrical signal and amplify it in multiple stages, or convert a second optical signal into a second electrical signal and amplify it in multiple stages.

[0095] In some embodiments, the photoelectric conversion efficiency of the PMT can be ≥80%, and the corresponding wavelength of the PMT matches the fluorescence wavelength of the scintillator 312.

[0096] It should be noted that the above description uses a glass light guide tube as the optical signal transmission channel 313 and a PMT as the photoelectric amplifier 314. Alternatively, the optical signal transmission channel 313 can be other components, and the photoelectric amplifier 314 can also include other components. This application does not limit this aspect.

[0097] In some embodiments, the first detection unit 31 and the second detection unit 32 are both ETD (Everhart-Thornley Detector) integrated structures. That is, the conductive block 311, scintillator 312, optical signal transmission channel 313 and photoelectric amplifier 314 in the first detection unit 31 and the second detection unit 32 are an inseparable whole module, rather than a scattered assembly.

[0098] In addition, in some embodiments, each first detection unit 31 and each second detection unit 32 has a control circuit and a data acquisition circuit, and the control circuit and data acquisition circuit are front-mounted and integrated into the pole shoe, which can shorten the optical signal transmission channel 313. Reducing the length of the glass light guide tube further reduces the loss of the first or second optical signal during transmission, shortens the transmission distance of weak signals at the front end, and improves the signal-to-noise ratio.

[0099] In some embodiments, please refer to Figure 6 The scanning electron microscope may also include at least one vacuum high-pressure feedthrough connector 5 (four are illustrated in the figure), which is configured on the sealing assembly 4 (the transition area between the vacuum detection zone and the atmospheric environment).

[0100] With the gap sealed, the vacuum high-pressure feedthrough connector 5 can transmit optical signals to the outside of the vacuum through the optical signal transmission channel 313 (i.e., the glass light guide tube). Specifically, the middle section of the glass light guide tube can pass through the sealing assembly 4 and be sealed by a compressed lateral O-ring. The rear end of the glass light guide tube extends into the atmospheric environment and is tightly fitted to the photoelectric amplifier 314. The lateral O-ring is fitted onto the outer circumference of the glass light guide tube, fitting between the outer circumference of the glass light guide tube and the hole wall of the sealing assembly 4. This allows for lossless transmission of the first and second optical signals from the vacuum detection area to the atmospheric environment. This vacuum feedthrough method enables the front end to complete signal acquisition in the vacuum and then transmit the signal to the processing circuitry outside the vacuum, avoiding the need to include these rear circuits and occupy the limited vacuum space.

[0101] In some embodiments, please refer to Figure 6The number of vacuum high-pressure feeder connectors 5 matches the number of detection components 3. For example, one set of detection components 3 can correspond to one vacuum high-pressure feeder connector 5, or multiple detection components 3 can be connected in parallel to one vacuum high-pressure feeder connector 5.

[0102] The input end of the vacuum high-voltage feedthrough connector 5 is connected to an external high-voltage power supply, and the output end is directly connected to the conductive block 311 of each first detection unit 31 and / or second detection unit 32 through a high-voltage wire, so as to realize the leakage-free conduction of high voltage from the atmospheric environment to the vacuum detection area. In addition, the connector of the vacuum high-voltage feedthrough connector 5 adopts a shielded design to avoid high voltage interference with the magnetic field of the objective lens 2.

[0103] In some embodiments, please refer to Figure 7 The scanning electron microscope also includes a control component 6, which performs a first bias voltage determination step on each first detection unit 31 and outputs a corresponding first bias voltage on each first detection unit 31. The first bias voltage determination step includes: determining the first bias voltage based on the first electric field control voltage, the position parameters of the first detection unit 31, and the objective lens current.

[0104] As described above, the first detection unit 31 is used to collect backscattered electron signals. Changing the bias voltage of the first detection unit 31 changes the voltage of the conductive block 311, thereby causing the scintillator 312 to have a negative attraction, i.e., a repulsive effect, on the secondary electrons. Therefore, the bias voltage of each first detection unit 31 needs to satisfy the condition that while repelling secondary electrons, it should not affect the landing of backscattered electrons on the scintillator 312 of the first detection unit 31 according to their own transmission path. That is, the negative attraction of the electric field generated by the bias voltage on the secondary electrons is greater than their deflection force in the magnetic field of the objective lens 2, and the electric field force on the backscattered electrons can be ignored. Therefore, the control component 6 needs to determine the first bias voltage of each first detection unit 31 and output the corresponding first bias voltage to the corresponding first detection unit 31, so that the scintillator 312 of the first detection unit 31 repels secondary electrons, so as to detect the backscattered electron signal more accurately.

[0105] Since the parameters (such as position parameters) corresponding to the first detection unit 31 at different positions are different, the corresponding first bias voltage may also be different. Therefore, for each first detection unit 31, the control component 6 needs to determine and output the first bias voltage corresponding to the first detection unit 31 so that different first detection units 31 can meet the requirement of negatively attracting secondary electrons while minimizing the impact on the landing of backscattered electrons on their own scintillator 312.

[0106] In some embodiments, the first bias voltage can be determined based on the first electric field regulating voltage, the position parameters of the first detection unit 31, and the objective lens current.

[0107] In some embodiments, the position parameters of the first detection unit 31 include a first position calibration coefficient, a first position correction coefficient, and a first radial distance corresponding to the first detection unit 31, wherein the first radial distance is used to indicate the distance between the first detection unit 31 and the central axis.

[0108] The first position calibration coefficient and the first position correction coefficient are both related to the geometric installation position and structural layout of the first detection unit 31. The first position calibration coefficient is used to linearly scale the original backscattered electron signal detected by the first detection unit 31, and the first position correction coefficient is used to compensate for the fixed zero position deviation caused by the geometric installation of the first detection unit 31. The first radial distance is the radial distance between the first detection unit 31 and the central axis of the first magnetic circuit assembly 21 and the second magnetic circuit assembly 22.

[0109] In some embodiments, the objective lens current is the driving current of the excitation coil of the objective lens 2. By changing the objective lens current, the intensity of the excitation magnetic field generated by the objective lens 2 can be changed, thereby changing the focusing degree and focusing position of the electron beam, so as to achieve adjustable control of the imaging focus, beam spot size and imaging clarity.

[0110] As an example, the first bias voltage can be determined according to the following formula (1);

[0111] (1)

[0112] Among them, U h K represents the first bias voltage. h U represents the calibration coefficient for the first position. C1 This represents the first electric field control voltage, which is the electron beam landing voltage U0 and the trap plate voltage U. C The sum of, i.e., U C1 =U0+U C M h R represents the first position correction factor, I represents the objective lens current, and r1 represents the first radial distance.

[0113] In some embodiments, after the electron beam emitted by the electron beam source 1 is applied to the sample before it reaches the sample, the electron beam is adjusted, such as by accelerating, decelerating, or adjusting its energy. Therefore, the energy of the electron beam landing on the sample surface may not be equal to the initial energy of the electron beam emitted by the electron beam source 1. Furthermore, the presence of a trap plate at the end of the objective lens barrel may further affect the energy of the electron beam, thus influencing the determination of the first bias voltage. The first electric field control voltage is the electron beam landing voltage and the energy of the electron beam at the end of the objective lens barrel (e.g., the trap plate at the end of the objective lens barrel). Figure 5The gray portion in the image represents the voltage difference between the trap plate (high voltage plate) and the sample, i.e., the trap plate voltage U. C The sum of these factors means that determining the first bias voltage based on the first electric field control voltage can reduce the impact of changes in the energy of the electron beam landing on the sample surface on the first bias voltage.

[0114] Among them, the first electric field control voltage U C1 The first bias voltage U is used to characterize the energy of the backscattered electron signal entering between the upper and lower magnetic circuit components (before it is affected by the bias voltage of the detection unit). h Based on the initial energy of the backscattered electrons (i.e., the first electric field control voltage U) C1 ), proportionally (i.e., the first position calibration coefficient K) h A certain negative bias voltage is applied to ensure that secondary electrons with lower energy are blocked from the outside, but to ensure that the initial energy of the backscattered electrons is still sufficient after being deducted by the negative bias voltage of the first detection unit, so that they can reach the probe receiving surface of the first detection unit.

[0115] Continuing with the above example, it can be seen from formula (1) that the first bias voltage is a negative bias voltage. In order to ensure that the obtained negative bias voltage satisfies the negative attraction of secondary electrons and does not affect the landing of backscattered electrons on the scintillator 312 of the first detection unit 31 as much as possible, the relationship between the various voltages needs to satisfy the following formula (2).

[0116] (2)

[0117] It should be noted that U0 and U C All are positive pressures, and are determined by the operating conditions of the scanning electron microscope. The aforementioned parameters and voltages can be acquired in real time or preset by the control component 6. This application embodiment does not limit this.

[0118] After determining the first bias voltage corresponding to each first detection unit 31, the control component 6 also needs to output its own corresponding first bias voltage to each first detection unit 31 so as to generate a high negative attraction effect on low-energy secondary electrons and have no significant impact on the transmission path of high-energy backscattered electrons.

[0119] In some embodiments, the control component 6 is further configured to: perform a second bias voltage determination step for each second detection unit 32, and output a corresponding second bias voltage for each second detection unit 32; the second bias voltage determination step includes: determining the second bias voltage based on the second electric field control voltage, the position parameters of the second detection unit 32, and the objective lens current.

[0120] As described above, the second detection unit 32 is used to collect secondary electron signals, and changing the bias voltage of the second detection unit 32 will change the voltage of the conductive block 311, thereby making the scintillator 312 have a positive attraction effect on the secondary electrons. Therefore, the bias voltage of each second detection unit 32 needs to meet the requirement of having a strong attraction effect on secondary electrons, and needs to work in conjunction with the magnetic field of the objective lens 2 to deflect the secondary electrons to the second detection unit 32. Therefore, the control component 6 needs to determine the second bias voltage of each second unit and output the corresponding second bias voltage to the corresponding second detection unit 32, so that the scintillator 312 of the second detection unit 32 positively attracts the secondary electrons, so as to detect the secondary electron signals more accurately.

[0121] Since the parameters (such as position parameters) corresponding to the second detection unit 32 at different positions are different, the corresponding second bias voltage may also be different. Therefore, for each second detection unit 32, the control component 6 needs to determine and output the second bias voltage corresponding to the second detection unit 32 so that different second detection units 32 meet the requirement of having a strong attraction to secondary electrons.

[0122] In some embodiments, the second bias voltage can be determined based on the second electric field regulating voltage, the position parameters of the second detection unit 32, and the objective lens current.

[0123] In some embodiments, the position parameters of the second detection unit 32 include a second position calibration coefficient, a second position correction coefficient, a second radial distance, a detection unit height, and a sample axial height. The detection unit height is used to indicate the distance between the second detection unit 32 and the sample, and the sample axial height is used to indicate the distance between the second magnetic circuit assembly 22 and the sample.

[0124] The second position calibration coefficient and the second position correction coefficient are both related to the geometric installation position and structural layout of the second detection unit 32. The second position calibration coefficient is used to linearly scale the original secondary electronic signal detected by the second detection unit 32, and the second position correction coefficient is used to compensate for the fixed zero position deviation caused by the geometric installation of the second detection unit 32. The second radial distance is the radial distance from the second detection unit 32 to the second magnetic circuit assembly 22 and the central axis of the second magnetic circuit assembly 22. The detection unit height is the height distance from the sample to the second detection unit 32. The sample axial height is the vertical distance from the sample to the lower pole shoe opening.

[0125] As an example, the second bias voltage can be determined according to the following formula (3);

[0126] (3)

[0127] Among them, U lK represents the second bias voltage. l U represents the calibration coefficient for the second position. C2 This represents the voltage controlled by the second electric field, which is the voltage U of the Trap Plate. C With the corresponding first bias voltage U h The difference, i.e., U C2 =U C -U h M l The second position correction factor is represented by r2, where I represents the objective lens current (for example, the objective lens current can be 1A~1.5A), r2 represents the second radial distance, and z2 represents the height of the detection unit. S This indicates the axial height of the sample.

[0128] Continuing with the above example, it can be seen from formula (3) that the second bias voltage is a positive bias voltage. In order to determine that the obtained positive bias voltage satisfies the strong attraction of the secondary electron and can work with the magnetic field of objective lens 2 to deflect the secondary electron to the second detection unit 32, the relationship between the various voltages needs to satisfy the following formula (4).

[0129] (4)

[0130] It should be noted that the aforementioned parameters and voltages can be acquired in real time or preset by the control component 6. This application embodiment does not limit this.

[0131] After determining the second bias voltage corresponding to each second detection unit 32, the control component 6 also needs to output its own corresponding second bias voltage to each second detection unit 32 to generate a positive attraction effect on the low-energy secondary electron signal, so that the trajectory of the secondary electron deflects toward the second detection unit 32.

[0132] Therefore, by applying a corresponding first bias voltage to each first detection unit 31 and a corresponding second bias voltage to each second detection unit 32, backscattered electrons can collide with the scintillator 312 of the first detection unit 31 along their own transmission path, enabling the first detection unit 31 to detect the backscattered electron signal; and secondary electron signals can collide with the scintillator 312 of the second detection unit 32, enabling the second detection unit 32 to detect the secondary electron signal, thus achieving accurate separation and detection of the backscattered electron signal and the secondary electron signal.

[0133] In some embodiments, based on the determined first bias voltage and second bias voltage, the bias voltage of each first detection unit 31 and each second detection unit 32 can be jointly adjusted to change the negative attraction degree of the scintillator 312 on the first detection unit 31 to the secondary electrons and the positive attraction degree of the scintillator 312 on the second detection unit 32 to the secondary electrons. This allows for precise control of the acquisition ratio of backscattered electron signals and secondary electron signals by at least one set of detection components 3, thereby adapting to the detection requirements of different samples.

[0134] In some embodiments, at least one set of detection components 3 has at least two detection modes, including a backscattered electron signal main acquisition mode and a secondary electron signal main acquisition mode.

[0135] When at least one set of detector components 3 is in the backscattered electron signal main acquisition mode, it means that at least one set of detector components 3 focuses on the acquisition of backscattered electron signals in order to perform more accurate sample analysis in subsequent processes; when at least one set of detector components 3 is in the secondary electron signal main acquisition mode, it means that at least one set of detector components 3 focuses on the acquisition of secondary electron signals in order to perform more accurate morphological imaging of the sample in subsequent processes.

[0136] In some embodiments, when at least one group of detection components 3 is in the backscattered electronic signal main acquisition mode, the control component 6 is further configured to: after performing a first bias voltage determination step for each first detection unit 31, for each first bias voltage: switch the first bias voltage to a third bias voltage, the polarity of the third bias voltage being opposite to the polarity of the first bias voltage; output a corresponding third bias voltage for each first detection unit 31; after performing a second bias voltage determination step for each second detection unit 32, for each second bias voltage: switch the second bias voltage to a fourth bias voltage, the fourth bias voltage being greater than the second bias voltage; output a corresponding fourth bias voltage for each second detection unit 32.

[0137] In other words, control component 6 needs to switch the polarity of each first bias voltage to obtain a third bias voltage corresponding to each first bias voltage, and then switch the first bias voltage to its corresponding third bias voltage. For example, assume the first bias voltage corresponding to the first detection unit 31A is U. H1 , and U H1 If the bias is negative, then control component 6 can control U H1 Switch to positive bias to obtain the first bias voltage U. H1 The corresponding third bias voltage; for example, suppose the first bias voltage corresponding to the first detection unit 31B is U. H2 , and U H2 If it is a positive bias, then control component 6 can control UH2 Switch to negative bias to obtain the first bias voltage U. H2 The corresponding third bias voltage.

[0138] Continuing from the above description, after the control component 6 determines the third bias voltage corresponding to each first detection unit 31, it can output a corresponding third bias voltage to each first detection unit 31 so that more backscattered electron signals can strike the scintillator 312 of the first detection unit 31 with higher energy.

[0139] When in the backscattered electron signal main acquisition mode, the second bias voltage of the second detection unit 32 also needs to be adjusted. The control component 6 can increase the second bias voltage to obtain the corresponding fourth bias voltage. That is, the fourth bias voltage is greater than its corresponding second bias voltage, and then the second bias voltage is switched to the fourth bias voltage.

[0140] Since the second detection unit 32 is closer to the entrance between the first magnetic circuit assembly 21 and the second magnetic circuit assembly 22, by increasing each second bias voltage, the positive attraction of each second detection unit 32 to secondary electrons can be enhanced, preventing the first detection unit 31 from detecting secondary electron signals. Furthermore, the resulting fourth bias voltage needs to avoid affecting the transmission path of backscattered electrons and causing discharge due to excessively high bias voltage.

[0141] Continuing from the above description, after the control component 6 determines the fourth bias voltage corresponding to each second detection unit 32, it can output the corresponding fourth bias voltage to each second detection unit 32. Thus, by jointly adjusting the bias voltage of each first detection unit 31 and each second detection unit 32, at least one set of detection components 3 can be made to focus on collecting backscattered electron signals.

[0142] When at least one set of detector components 3 is in the secondary electron signal main acquisition mode, it means that at least one set of detector components 3 focuses on the acquisition of secondary electron signals in order to perform more accurate morphological imaging of the sample in subsequent processes.

[0143] In some embodiments, when at least one group of detection components 3 is in the secondary electronic signal main acquisition mode, the control component 6 is further configured to: after performing the second bias voltage determination step for each second detection unit 32, for each second bias voltage: switch the second bias voltage to a fifth bias voltage, the fifth bias voltage being greater than the second bias voltage and less than a voltage threshold; output a corresponding fifth bias voltage for each second detection unit 32; after performing the first bias voltage determination step for each first detection unit 31, for each first bias voltage: determine a sixth bias voltage based on the fifth bias voltage, the absolute value of the sixth bias voltage being less than the fifth bias voltage; switch the first bias voltage to the sixth bias voltage, and then output a corresponding sixth bias voltage for each first detection unit 31.

[0144] In other words, control component 6 needs to boost each second bias voltage to obtain a fifth bias voltage corresponding to each second bias voltage. That is, the fifth bias voltage is greater than its corresponding second bias voltage, and then the second bias voltage is switched to its corresponding fifth bias voltage. Furthermore, to avoid high-voltage breakdown, the obtained fifth bias voltage also needs to be less than a voltage threshold. For example, the fifth bias voltage may not be greater than 15kV.

[0145] When in the secondary electronic signal main acquisition mode, the first bias voltage of the first detection unit 31 also needs to be adjusted. The control component 6 can determine the corresponding sixth bias voltage based on each fifth bias voltage. For example, detection component 3A includes a first detection unit 31A and a second detection unit 32A, detection component 3B includes a first detection unit 31B and a second detection unit 32B, and detection component 3C includes a first detection unit 31C and a second detection unit 32C. If the fifth bias voltage of the second detection unit 32A is X1, then the sixth bias voltage Y1 of the first detection unit 31A can be determined based on X1; if the fifth bias voltage of the second detection unit 32B is X2, then the sixth bias voltage Y2 of the first detection unit 31B can be determined based on X2; if the fifth bias voltage of the second detection unit 32C is X3, then the sixth bias voltage Y3 of the first detection unit 31C can be determined based on X3.

[0146] In some embodiments, in order to minimize the proportion of secondary electron signals collected by the first detection unit 31 and to avoid the backscattered electron signals of the first detection unit 31 being negatively attracted to the bias region of the second detection unit 32 due to an excessively high absolute value of the sixth bias voltage, the absolute value of the sixth bias voltage needs to be less than the fifth bias voltage. As an example, assuming the fifth bias voltage X1 is a positive bias voltage and its corresponding sixth bias voltage is Y1, then |Y1| needs to be less than X1.

[0147] Continuing from the above description, after determining the sixth bias voltage corresponding to each first detection unit 31, a corresponding sixth bias voltage can be output to each first detection unit 31. Thus, by jointly adjusting the bias voltages of each first detection unit 31 and each second detection unit 32, at least one set of detection components 3 can be made to focus on acquiring secondary electronic signals.

[0148] In some embodiments, the receiving surface of the scintillator 312 of the first detection unit 31 in each group of detection components 3 can be oriented toward the transmission path of the backscattered electronic signal, so that the first detection unit 31 can also detect the backscattered electronic signal more accurately when no bias voltage is applied to the first detection unit 31.

[0149] In some embodiments, the receiving surface of the scintillator 312 of the second detection unit 32 in each set of detection components 3 can face the transmission path of the secondary electronic signal, so that the second detection unit 32 can also detect the secondary electronic signal more accurately when no bias voltage is applied. Alternatively, the receiving surface of the scintillator 312 of the second detection unit 32 can also avoid the transmission path of the backscattered electronic signal to avoid interfering with the detection of the backscattered electronic signal by the first detection unit 31.

[0150] In some embodiments, please refer to Figure 8 The scanning electron microscope may include multiple control components 6 (four are illustrated in the figure), from Figure 8 As can be seen, the control component 6 and the detection component 3 correspond one-to-one. Therefore, the control component 6 can determine the bias voltage of the first detection unit 31 and the second detection unit 32 in its corresponding detection component 3 and output it.

[0151] In some embodiments, the scanning electron microscope may further include a human-computer interaction component, such as a touch screen or keyboard, to allow the user to select at least one set of acquisition modes for the detection components 3, such as a backscattered electron signal main acquisition mode and a secondary electron signal main acquisition mode. If the user does not select an acquisition mode, the default acquisition mode is used, i.e., the control component 6 outputs a corresponding first bias voltage to each first detection unit 31 and a corresponding second bias voltage to each second detection unit 32, so that each first detection unit 31 detects backscattered electron signals and each second detection unit 32 detects secondary electron signals, thereby performing a comprehensive measurement of the sample's morphology imaging and composition analysis.

[0152] In some embodiments, other acquisition modes may also be included, such as full signal acquisition mode and backscattered electronic signal dedicated acquisition mode.

[0153] In full signal acquisition mode, the control component 6 can apply a positive bias voltage to each first detection unit 31 and each second detection unit 32 to acquire all backscattered electron signals and secondary electron signals, thereby improving detection efficiency and increasing the total signal quantity when detecting samples with low signal intensity.

[0154] In the dedicated backscattered electron signal acquisition mode, the control component 6 can apply a zero bias voltage to each first detection unit 31 and a negative bias voltage to each second detection unit 32 to completely negatively attract secondary electrons, that is, completely repel secondary electrons and only acquire backscattered electron signals. Thus, the interference of secondary electron signals can be eliminated, and the sample can be accurately analyzed in terms of composition.

[0155] By employing different signal acquisition modes, this scanning electron microscope can be adapted to various sample detection needs, thus expanding its application scenarios. It should be noted that the signal acquisition modes described above are merely illustrative examples; other signal acquisition modes may also be included in actual applications. This application does not limit the scope of these modes.

[0156] In some embodiments, please refer to Figure 9 The control component 6 includes a high-precision high-voltage power supply 61, a voltage regulation module 62, and a wire 63.

[0157] The high-precision high-voltage power supply 61 is used to output positive / negative bias voltages to the first detection unit 31 and the second detection unit 32, and has high adjustment accuracy of the bias voltage, enabling it to provide stable bias voltages for both units. For example, the high-precision high-voltage power supply 61 can output a bias voltage ranging from -1000V to +15000V, with a voltage adjustment accuracy ≤1V.

[0158] The voltage regulation module 62 has a built-in microprocessor that can determine the first bias voltage and the second bias voltage in real time based on changes in electron beam landing voltage, objective lens current, etc. It automatically adjusts the bias voltage of each first detection unit 31 based on the determined first bias voltage, and automatically adjusts the bias voltage of each second detection unit 32 based on the determined second bias voltage. For example, it can switch the first bias voltage to a third bias voltage, the second bias voltage to a fourth bias voltage, the second bias voltage to a fifth bias voltage, and the first bias voltage to a sixth bias voltage, etc., achieving linkage and matching with the operating parameters of the scanning electron microscope.

[0159] In some embodiments, the conductor 63 is a vacuum high-temperature resistant silver-plated conductor, which is connected to the vacuum high-voltage feeder connector 5 and the conductive block 311 to reduce the bias voltage loss and improve stability during transmission.

[0160] In some embodiments, the scanning electron microscope further includes an imaging system for high-resolution imaging and compositional analysis of the sample based on a first electrical signal and / or a second electrical signal.

[0161] It should be noted that existing or future technologies can be used to perform morphological imaging and composition analysis on samples, which will not be elaborated in the embodiments of this application.

[0162] This embodiment of the application, by configuring at least one set of detection components within the gap between the first magnetic circuit component and the second magnetic circuit component, uses this gap as a detection area to accurately detect low-angle secondary electron signals and backscattered electron signals. Each set of detection components includes a first detection unit and a second detection unit. The first detection unit is positioned on the transmission path of the backscattered electrons to detect the backscattered electron signal, and the second detection unit is positioned on the transmission path of the secondary electron signal to detect the secondary electron signal. This allows for the separate detection of the secondary electron signal and the backscattered electron signal, achieving efficient separation of the two signals, increasing the number and efficiency of signal acquisition, and thus improving image resolution. Furthermore, by applying a corresponding first bias voltage to each first detection unit and a corresponding second bias voltage to each second detection unit, backscattered electrons can collide with the scintillator of the first detection unit along their own transmission path, enabling the first detection unit to detect the backscattered electron signal; conversely, the secondary electron signal can collide with the scintillator of the second detection unit, enabling the second detection unit to detect the secondary electron signal, thus achieving accurate separation and detection of the backscattered electron signal and the secondary electron signal. Furthermore, by jointly adjusting the bias voltages of the first and second detection units, the negative attraction of the scintillator on the first detection unit to secondary electrons and the positive attraction of the scintillator on the second detection unit to secondary electrons can be changed. This allows for precise control of the acquisition ratio of backscattered electron signals and secondary electron signals by at least one set of detection components, thereby adapting to the detection needs of different samples and expanding the application scenarios of scanning electron microscopy. In addition, the integrated sealed design of the detection components and detection area eliminates the need for additional telescopic structures and external detectors, simplifying the assembly of the objective lens barrel.

[0163] This document describes various exemplary embodiments with reference to them. However, those skilled in the art will recognize that changes and modifications can be made to the exemplary embodiments without departing from the scope of this document. For example, various operational steps and components for performing operational steps can be implemented in different ways depending on the specific application or considering any number of cost functions associated with the operation of the system (e.g., one or more steps can be deleted, modified, or combined with other steps).

[0164] While the principles herein have been illustrated in various embodiments, numerous modifications to the structures, arrangements, proportions, elements, materials, and components, particularly suited to specific environments and operational requirements, may be used without departing from the principles and scope of this disclosure. These modifications and other alterations or alterations will be included within the scope of this document. Those skilled in the art will recognize that many changes can be made to the details of the above embodiments without departing from the fundamental principles of the invention.

Claims

1. A scanning electron microscope, characterized in that, include: An electron beam source is used to emit an electron beam. An objective lens is used to focus the electron beam onto the sample. The objective lens includes a first magnetic circuit assembly and a second magnetic circuit assembly, with a gap formed between the first magnetic circuit assembly and the second magnetic circuit assembly; At least one set of detection components is provided for detecting the electronic signal generated by the interaction between the electron beam and the sample, and the detection components are disposed within the gap; Each of the at least one set of detection components includes a first detection unit and a second detection unit. Each first detection unit is disposed on the transmission path of the backscattered electron signal and is used to detect the backscattered electron signal. Each second detection unit is disposed on the transmission path of the secondary electron signal and is used to detect the secondary electron signal.

2. The scanning electron microscope as described in claim 1, characterized in that, The at least one set of detection components are evenly distributed circumferentially around the central axis of the first magnetic circuit component and the second magnetic circuit component.

3. The scanning electron microscope as described in claim 2, characterized in that, Each first detection unit is disposed adjacent to the first magnetic circuit component, and the distance between each first detection unit and the first magnetic circuit component is not less than a distance threshold. Each second detection unit is disposed adjacent to the second magnetic circuit assembly, and the distance between each second detection unit and the second magnetic circuit assembly is not less than the distance threshold.

4. The scanning electron microscope as described in claim 3, characterized in that, The scanning electron microscope also includes: A control component is used to perform a first bias voltage determination step for each first detection unit and output a corresponding first bias voltage for each first detection unit; The first bias voltage determination step includes: The first bias voltage is determined based on the first electric field regulating voltage, the position parameters of the first detection unit, and the objective lens current.

5. The scanning electron microscope as described in claim 4, characterized in that, The position parameters of the first detection unit include a first position calibration coefficient, a first position correction coefficient, and a first radial distance corresponding to the first detection unit. The first radial distance is used to indicate the distance between the first detection unit and the central axis.

6. The scanning electron microscope as described in claim 4, characterized in that, The control component is also used for: Perform a second bias voltage determination step for each second detection unit, and output a corresponding second bias voltage for each second detection unit; The second bias voltage determination step includes: The second bias voltage is determined based on the second electric field regulating voltage, the position parameters of the second detection unit, and the objective lens current.

7. The scanning electron microscope as described in claim 6, characterized in that, The position parameters of the second detection unit include the second position calibration coefficient, the second position correction coefficient, the second radial distance, the detection unit height, and the sample axial height. The detection unit height is used to indicate the distance between the second detection unit and the sample, and the sample axial height is used to indicate the distance between the second magnetic circuit assembly and the sample.

8. The scanning electron microscope as described in claim 6, characterized in that, The at least one set of detection components has at least two detection modes, including a backscattered electron signal main acquisition mode and a secondary electron signal main acquisition mode.

9. The scanning electron microscope as described in claim 8, characterized in that, When at least one set of detection components is in the backscattered electron signal main acquisition mode, the control component is further configured to: After performing the first bias voltage determination step for each first detection unit, for each first bias voltage: the first bias voltage is switched to a third bias voltage, the polarity of which is opposite to that of the first bias voltage; A corresponding third bias voltage is output for each first detection unit; After performing the second bias voltage determination step for each second detection unit, for each second bias voltage: the second bias voltage is switched to a fourth bias voltage, the fourth bias voltage being greater than the second bias voltage; A corresponding fourth bias voltage is output for each second detection unit.

10. The scanning electron microscope as described in claim 8, characterized in that, When at least one set of detection components is in the secondary electronic signal main acquisition mode, the control component is further configured to: After performing the second bias voltage determination step for each second detection unit, for each second bias voltage: the second bias voltage is switched to a fifth bias voltage, which is greater than the second bias voltage and less than a voltage threshold. A corresponding fifth bias voltage is output for each second detection unit; After performing the first bias voltage determination step for each first detection unit, for each first bias voltage: a sixth bias voltage is determined based on the fifth bias voltage, wherein the absolute value of the sixth bias voltage is less than the fifth bias voltage; Switch the first bias voltage to the sixth bias voltage; A corresponding sixth bias voltage is output for each first detection unit.

11. The scanning electron microscope as described in claim 3, characterized in that, Each first detection unit and each second detection unit includes a conductive block and a scintillator; The conductive block is disposed on the scintillator. The conductive block is used to apply its own voltage to the scintillator to change the degree of attraction of the scintillator to secondary electrons. The voltage of the conductive block is equal to the bias voltage of its corresponding first detection unit or second detection unit. The scintillator is also used to convert the detected backscattered electron signal into a first optical signal, or to convert the detected secondary electron signal into a second optical signal.

12. The scanning electron microscope as described in claim 11, characterized in that, Each first detection unit and each second detection unit also include an optical signal transmission channel and a photoelectric amplifier; The optical signal transmission channel is located after the scintillator and is used to transmit the first optical signal or the second optical signal to the photoelectric amplifier. The photoelectric amplifier is used to convert the first optical signal into a first electrical signal, or to convert the second optical signal into a second electrical signal.

13. The scanning electron microscope according to any one of claims 1 to 12, characterized in that, The scanning electron microscope also includes: A sealing assembly is used to seal the gap so that the detection area of ​​the at least one set of detection components is a vacuum detection zone.

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