Sample detection device and sample detection method

Abstract

The present invention discloses a sample detection device and a sample detection method. The sample detection device includes: an electron emission module, a sample stage, an electromagnetic focusing module, at least one detector, and a processing module; the electromagnetic focusing module is located on the running path of the detection particle, and the electromagnetic focusing module includes a pole shoe and a magnetic field generating unit, and the pole shoe partially surrounds the magnetic field generating unit; the pole shoe includes an upper pole shoe and a lower pole shoe, the upper pole shoe is connected to the lower pole shoe and electrically isolated, and the upper pole shoe and the lower pole shoe are used to jointly constrain the magnetic field generated by the magnetic field generating unit; the lower pole shoe serves as a control electrode when connected to an external power supply, and the control electrode is used to adjust the motion state of the detection particle through the electric field. The embodiment of the present invention solves the problem that the sample detection device has reduced signal collection efficiency and imaging quality due to the addition of an external control electrode.

Description

Technical Field

[0001] The present invention relates to the technical field of sample detection, and in particular to a sample detection device and a sample detection method. Background Art

[0002] Scanning electron microscope is an important tool for analyzing micro- and nano-scale materials. It uses electron beam to excite samples to generate secondary electrons, backscattered electrons and other detection particles for imaging analysis.

[0003] In the prior art, scanning electron microscopes generally adopt an independently arranged control electrode structure, that is, an electrode assembly is installed on the periphery of the electromagnetic lens, and an axial electric field is formed by applying a bias voltage.

[0004] However, increasing the physical distance between the external electrodes and the electromagnetic lens can distort the field distribution. Furthermore, the external electrodes can cause the detector mounting position to shift outward, increasing scattering noise and reducing signal collection efficiency, ultimately degrading imaging quality. Summary of the Invention

[0005] The embodiments of the present invention provide a sample detection device and a sample detection method to solve the problem that the signal collection efficiency and imaging quality of the sample detection device are reduced due to the addition of an external control electrode.

[0006] In a first aspect, an embodiment of the present invention provides a sample detection device, comprising: an electron emission module, a sample stage, an electromagnetic focusing module, at least one detector, and a processing module;

[0007] The transmitting module is used for transmitting the electron beam;

[0008] The sample stage is used to carry the sample to be tested, and the sample stage is located on the running path of the electron beam; the electron beam bombards the sample to be tested to generate detection particles;

[0009] The electromagnetic focusing module is located on the running path of the detection particles and is used to adjust the motion state of the detection particles through magnetic and electric fields;

[0010] The electromagnetic focusing module includes a pole shoe and a magnetic field generating unit, wherein the pole shoe part surrounds the magnetic field generating unit;

[0011] The magnetic field generating unit is used to adjust the motion state of the detection particles through the magnetic field;

[0012] The pole shoe comprises an upper pole shoe and a lower pole shoe, the upper pole shoe is connected to the lower pole shoe and is electrically isolated from the lower pole shoe, and the magnetic permeability of the upper pole shoe and the lower pole shoe is greater than or equal to a first preset magnetic permeability threshold;

[0013] The upper pole shoe and the lower pole shoe are used to jointly constrain the magnetic field generated by the magnetic field generating unit;

[0014] The lower pole piece acts as a control electrode when connected to an external power supply. The control electrode is used to adjust the motion state of the detection particle through the electric field.

[0015] The detector is used to receive the detection particles conditioned by the electromagnetic focusing module and generate a detection signal according to the detection particles;

[0016] The processing module is connected to the detector and is used to determine the detection information of the sample to be tested according to the detection signal.

[0017] Optionally, the lower pole shoe serves as a contrast adjustment electrode when connected to an external power supply. The contrast adjustment electrode is used to adjust image contrast, and the maximum voltage of the contrast adjustment electrode is less than the first preset voltage.

[0018] Optionally, the upper pole shoe comprises a magnetically conductive insulating material, and the lower pole shoe comprises a first magnetically conductive conductor material;

[0019] The upper pole shoe is in contact with the lower pole shoe;

[0020] In which, the magnetic permeability of the magnetic insulating material is greater than the second preset magnetic permeability threshold, the magnetic permeability of the first magnetic conductive material is greater than or equal to the third preset magnetic permeability threshold; the second preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold; the third preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold.

[0021] Optionally, the upper pole shoe comprises a second magnetically conductive material, the lower pole shoe comprises a second magnetically conductive material, and the pole shoe further comprises an isolation structure located between the upper pole shoe and the lower pole shoe, the isolation structure connecting the upper pole shoe and the lower pole shoe respectively;

[0022] The magnetic permeability of the second magnetic conductive material is greater than a fourth preset magnetic permeability threshold; and the fourth preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold.

[0023] Optionally, the isolation structure includes a magnetically conductive isolation structure;

[0024] The magnetic permeability of the magnetic isolation structure is greater than a fifth preset magnetic permeability threshold; the fifth preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold.

[0025] Optionally, the thickness d of the isolation structure satisfies 0.1 μm≤d≤50 μm.

[0026] Optionally, the at least one detector includes a first detector, the first detector is arranged between the lower pole shoe and the electron emission module, and the first detector is used to receive detection particles within a first reflection angle range;

[0027] And / or, at least one detector includes a second detector, which is arranged between the sample stage and the lower pole shoe; the second detector is used to receive detection particles within a second reflection angle range; the second reflection angle range is smaller than the first reflection angle range.

[0028] In a second aspect, an embodiment of the present invention further provides a sample detection method applicable to any sample detection device in the first aspect, the detection method comprising:

[0029] Controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles;

[0030] Adjust the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles;

[0031] The receiving detector determines the detection information of the sample to be tested based on the detection signal fed back by the detection particles.

[0032] Optionally, the lower electrode shoe serves as a contrast adjustment electrode when connected to an external power supply, and the maximum voltage of the contrast adjustment electrode is less than a first preset voltage;

[0033] Adjust the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles, including:

[0034] Adjust the external voltage of the lower pole shoe to adjust the image contrast.

[0035] Optionally, adjust the external voltage of the lower pole piece to adjust the image contrast, including:

[0036] Lower the external voltage of the lower pole shoe and reduce the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the impact of the external voltage adjustment on the electron beam; or,

[0037] Increase the external voltage of the lower pole shoe and increase the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the impact of the external voltage adjustment on the electron beam;

[0038] The magnetic field gradient is the difference between the magnetic field strength value close to the axis where the electron beam is located and the magnetic field strength value far from the axis where the electron beam is located.

[0039] Optionally, the external voltage of the lower pole shoe is lowered, and the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit are reduced to reduce the influence of the external voltage adjustment on the electron beam; or the external voltage of the lower pole shoe is increased, and the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit are increased to reduce the influence of the external voltage adjustment on the electron beam, including:

[0040] Lower the external voltage of the lower pole shoe and reduce the excitation current at the same time to reduce the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit and reduce the impact of the external voltage adjustment on the electron beam; or

[0041] The external voltage of the lower pole shoe is increased, and the excitation current is increased at the same time to increase the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit and reduce the influence of the external voltage adjustment on the electron beam.

[0042] Optionally, the detection information of the sample to be tested includes clarity;

[0043] After adjusting the external voltage of the lower pole shoe to adjust the image contrast, the following steps are also included:

[0044] The excitation current is adjusted based on the clarity to reduce the influence of external voltage adjustment on the electron beam.

[0045] Optionally, after controlling the electron emission module to emit an electron beam to the sample to be tested so that the electron beam bombards the sample to be tested to generate detection particles, the method further includes:

[0046] The external voltage of the lower pole shoe is adjusted to adjust the detection particle collection efficiency and / or collection ratio of the detector.

[0047] Optionally, the detector includes a first detector;

[0048] Adjust the external voltage of the lower pole piece to adjust the particle collection efficiency and / or collection ratio of the detector, including:

[0049] Adjust the external voltage of the lower pole shoe to be higher than the voltage of the sample stage, thereby improving the detection particle collection efficiency of the first detector and increasing the collection ratio of secondary electrons; or,

[0050] The external voltage of the lower pole shoe is adjusted to be lower than the voltage of the sample stage to reduce the interference of secondary electrons on the first detector and increase the collection ratio of backscattered electrons.

[0051] Optionally, the detector includes a second detector;

[0052] Adjusting the external voltage of the lower pole piece to adjust the detection particle collection efficiency and / or collection ratio of the detector includes:

[0053] Adjust the external voltage of the lower pole shoe to be higher than the voltage of the sample stage, thereby improving the collection efficiency of the second detector for detection particles with a reflection angle smaller than the first preset reflection angle; or,

[0054] Adjusting the external voltage of the lower pole shoe to be lower than the voltage of the sample stage to improve the collection efficiency of the second detector for detection particles with a reflection angle greater than a second preset reflection angle; the second preset reflection angle is greater than the first preset reflection angle;

[0055] The reflection angle is the angle between the detection particle and the horizontal plane of the sample stage.

[0056] The embodiment of the present invention provides a sample detection device and a sample detection method. The sample detection device includes an electron emission module, a sample stage, an electromagnetic focusing module, at least one detector, and a processing module. The transmitting module is used to emit an electron beam; the sample stage is used to carry the sample to be tested, and the sample stage is located on the running path of the electron beam; the electron beam bombards the sample to be tested to generate detection particles; the electromagnetic focusing module is located on the running path of the detection particles, and is used to adjust the motion state of the detection particles through magnetic fields and electric fields; the electromagnetic focusing module includes a pole shoe and a magnetic field generating unit, and the pole shoe part surrounds the magnetic field generating unit; the magnetic field generating unit is used to adjust the motion state of the detection particles through the magnetic field; the pole shoe includes an upper pole shoe and a lower pole shoe, the upper pole shoe is connected to the lower pole shoe and is electrically isolated, and the magnetic permeability of the upper pole shoe and the lower pole shoe is greater than or equal to a first preset magnetic permeability threshold; the upper pole shoe and the lower pole shoe are used to jointly constrain the magnetic field generated by the magnetic field generating unit; the lower pole shoe acts as a control electrode when connected to an external power supply, and the control electrode is used to adjust the motion state of the detection particles through an electric field; the detector is used to receive the detection particles adjusted by the electromagnetic focusing module, and generate a detection signal based on the detection particles; the processing module is connected to the detector, and is used to determine the detection information of the sample to be tested based on the detection signal. This device electrically isolates the lower pole piece of the electromagnetic focusing module and reuses it as a control electrode, addressing the reduced signal collection efficiency and image quality associated with conventional external control electrodes. By connecting the lower pole piece to an external power source to generate an axial electric field, the trajectory of the probe particles is regulated, improving signal reception efficiency and image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is a structural schematic diagram of a sample detection device provided by an embodiment of the present invention;

[0058] Figure 2 is a structural schematic diagram of another sample detection device provided by an embodiment of the present invention;

[0059] Figure 3 is a flow chart of a sample detection method provided by an embodiment of the present invention;

[0060] Figure 4 is a flow chart of another sample detection method provided by an embodiment of the present invention;

[0061] Figure 5 This is a flow chart of another sample detection method provided by an embodiment of the present invention;

[0062] Figure 6 Schematic diagram of a scanning electron microscope of a sample to be tested provided by an embodiment of the present invention with an accelerating electric field of 3 kV and a lower pole shoe connected to an external voltage of +100 kV;

[0063] Figure 7 yes Figure 6Schematic diagram of the scanning electron microscope of the sample to be tested after the magnetic field intensity and magnetic field gradient are increased simultaneously;

[0064] Figure 8 This is a flow chart of another sample detection method provided by an embodiment of the present invention;

[0065] Figure 9 This is a flow chart of another sample detection method provided by an embodiment of the present invention;

[0066] Figure 10 This is a schematic diagram of a scanning electron microscope of a sample to be tested provided by an embodiment of the present invention, in which the accelerating electric field is 3 kV, the lower pole shoe is connected to 0 V, and the detected particles are mainly secondary electrons;

[0067] Figure 11 yes Figure 10 Schematic diagram of a scanning electron microscope (SEM) of a sample under test with a medium accelerating electric field of 3 kV and a lower pole shoe connected to -135 V. The detected particles are mainly backscattered electrons.

[0068] Figure 12 This is a flow chart of another sample detection method provided by an embodiment of the present invention;

[0069] Figure 13 This is a schematic diagram of a scanning electron microscope of a sample to be measured provided by an embodiment of the present invention, with an accelerating electric field of 3 kV, a lower pole shoe connected to 0 V, and the shallow morphology of the sample surface;

[0070] Figure 14 for Figure 13 Schematic diagram of the scanning electron microscope of the sample to be tested with the medium accelerating electric field of 3kV, the lower pole shoe connected to -250V, and the sample composition image. DETAILED DESCRIPTION

[0071] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0072] The present invention provides a sample detection device, Figure 1 is a structural diagram of a sample detection device provided by an embodiment of the present invention, Figure 2 FIG. 1 is a schematic structural diagram of another sample detection device provided by an embodiment of the present invention. Figure 1-Figure 2 As shown, the sample detection device includes: an electron emission module 100, a sample stage 200, an electromagnetic focusing module 300, at least one detector 400 and a processing module (not shown in the figure).

[0073] The electron emission module 100 is used to emit electron beams.

[0074] The sample stage 200 is used to carry the sample to be tested, and the sample stage 200 is located on the running path of the electron beam. The electron beam bombards the sample to be tested to generate detection particles.

[0075] The electromagnetic focusing module 300 is located on the running path of the detection particles and is used to adjust the motion state of the detection particles through magnetic fields and electric fields.

[0076] The electromagnetic focusing module 300 includes a pole shoe 310 and a magnetic field generating unit 320 , wherein the pole shoe 310 partially surrounds the magnetic field generating unit 320 .

[0077] The magnetic field generating unit 320 is used to adjust the motion state of the detection particles through the magnetic field.

[0078] The pole shoe 310 includes an upper pole shoe 311 and a lower pole shoe 312 . The upper pole shoe 311 is connected to the lower pole shoe 312 and is electrically isolated. The magnetic permeability of the upper pole shoe 311 and the lower pole shoe 312 is greater than or equal to a first preset magnetic permeability threshold.

[0079] The upper pole shoe 311 and the lower pole shoe 312 are used to jointly constrain the magnetic field generated by the magnetic field generating unit 320 .

[0080] The lower pole piece 312 serves as a control electrode when connected to an external power supply. The control electrode is used to adjust the motion state of the detection particles through the electric field.

[0081] The detector 400 is used to receive the detection particles conditioned by the electromagnetic focusing module 300 and generate a detection signal according to the detection particles.

[0082] The processing module is connected to the detector 400 and is used to determine the detection information of the sample to be tested according to the detection signal.

[0083] Among them, the first preset magnetic permeability threshold can be understood as the minimum relative magnetic permeability required for the normal operation of the pole shoe 310; the detection signal can be understood as the electrical signal generated by energy conversion after the detector 400 receives the detection particles (secondary electrons, backscattered electrons, etc.). The signal contains physical information (morphology, composition, etc.) of the sample surface, and its characteristics (such as intensity, waveform) are related to the number and energy distribution of the incident particles.

[0084] Specifically, refer to Figure 1 In the process of determining the detection information of the sample to be tested, the electron emission module 100 generates a high-energy electron beam, which is focused and accelerated and then emitted toward the sample stage 200 below along the axis direction.

[0085] After entering the electromagnetic focusing module 300, the electron beam undergoes dual regulation of magnetic and electric fields. The strong magnetic field generated by the magnetic field generating unit 320 is confined by the upper and lower pole pieces 311 and 312, forming a high-gradient magnetic field region. The Lorentz force causes the diverging electron beam to converge toward the axis, narrowing its spatial distribution to ensure that upon reaching the sample under test, it impacts the target detection range.

[0086] In an optional embodiment, the sample detection device of the present invention may include multiple magnetic field generating units 320 (magnetic lenses). The divergent electron beam passes through the multiple magnetic field generating units 320, gradually narrowing the spatial distribution range and finally completely converging to the target detection range.

[0087] The sample stage 200 carries the sample to be tested. When the electron beam strikes the sample surface, it interacts with the sample atoms, stimulating secondary electrons, backscattered electrons, and other detection particles. These particles carry information about the sample's surface morphology and composition, scatter in all directions, and are captured by the detector 400.

[0088] After receiving the detection particles, the detector 400 (such as a scintillator-photomultiplier tube assembly) converts the energy of the detection particles into an electrical signal (such as a current pulse), namely a detection signal, which reflects the characteristics of the sample surface.

[0089] When connected to an external power source, lower pole piece 312 functions as a control electrode, forming an axial electric field with sample stage 200. This axial electric field exerts a Coulomb force on probe particles (such as secondary electrons and backscattered electrons), further regulating their motion direction and velocity. For example, it accelerates low-energy secondary electrons toward detector 400, adjusts the trajectory of probe particles, improves signal reception efficiency and imaging quality, or offsets trajectory deviations caused by the magnetic field, corrects the particle path, and reduces scattering noise.

[0090] Illustratively, by changing the voltage of the external power supply connected to the lower pole shoe 312, different potential differences can be created between the lower pole shoe 312 and the sample stage 200, thereby forming electric fields in different directions (the potential of the lower pole shoe 312 is positive relative to the sample stage, or the potential of the lower pole shoe 312 is negative relative to the sample stage). Different electric fields will have different effects on the detected charged particles. Taking the negatively charged detected charged particles (electrons) as an example, when the potential of the lower pole shoe 312 is positive relative to the sample stage, low-energy secondary electrons are accelerated to move toward the detector 400, the motion trajectory of the detected particles is adjusted, and the signal reception efficiency and imaging quality are improved; when the potential of the lower pole shoe 312 is negative relative to the sample stage 200, the trajectory deviation caused by the magnetic field is offset, the particle path is corrected, and the scattering noise is reduced.

[0091] It should be noted that during electron beam acceleration, the influence of the lower pole shoe 312 on the electron beam can be mitigated by setting an electron beam accelerating electric field (such as an accelerating tube or accelerating electrode) with an accelerating voltage of at least 2 kV (typically 8 kV), grounding the sample stage 200 at 0 V, and applying an external voltage between -100 V and 100 V (preferably between -50 V and 50 V) to the lower pole shoe 312. At this point, the kinetic energy of the electron beam is extremely high, and its trajectory is primarily regulated by the strong accelerating electric field and the magnetic field generated by the magnetic field generating unit 320. Because the external voltage applied by the lower pole shoe 312 is significantly lower than the voltage applied by the accelerating electric field, the electric field generated by the lower pole shoe 312 has a negligible deflection effect on the electron beam and can therefore be ignored.

[0092] An embodiment of the present invention provides a sample detection device, which includes an electron emission module, a sample stage, an electromagnetic focusing module, at least one detector, and a processing module. The emission module is configured to emit an electron beam; the sample stage is configured to carry a sample to be tested and is located in the path of the electron beam; the electron beam bombards the sample to be tested to generate detection particles; the electromagnetic focusing module is located in the path of the detection particles and is configured to regulate the motion state of the detection particles through magnetic and electric fields; the electromagnetic focusing module includes a pole shoe and a magnetic field generating unit, with the pole shoe partially surrounding the magnetic field generating unit; the magnetic field generating unit is configured to regulate the motion state of the detection particles through a magnetic field; the pole shoe includes an upper pole shoe and a lower pole shoe, the upper pole shoe being connected to and electrically isolated from the lower pole shoe, and the magnetic permeability of the upper pole shoe and the lower pole shoe being greater than or equal to a first preset magnetic permeability threshold; the upper pole shoe and the lower pole shoe are configured to jointly constrain the magnetic field generated by the magnetic field generating unit; the lower pole shoe, when connected to an external power supply, serves as a control electrode, and the control electrode is configured to regulate the motion state of the detection particles through an electric field; the detector is configured to receive the detection particles regulated by the electromagnetic focusing module and generate a detection signal based on the detection particles; and the processing module is connected to the detector and is configured to determine detection information of the sample to be tested based on the detection signal. This device electrically isolates the lower pole piece of the electromagnetic focusing module and reuses it as a control electrode, addressing the reduced signal collection efficiency and image quality associated with conventional external control electrodes. By connecting the lower pole piece to an external power source to generate an axial electric field, the trajectory of the probe particles is regulated, improving signal reception efficiency and image quality.

[0093] In an optional embodiment, the lower pole piece 312 serves as a contrast adjustment electrode when connected to an external power source. The contrast adjustment electrode is used to adjust image contrast, and the maximum voltage of the contrast adjustment electrode is less than the first preset voltage.

[0094] Among them, contrast can be understood as the degree of difference in brightness or color between different areas in the image. High contrast means that the contrast between adjacent areas in the image is large, and the details are clearer and easier to distinguish; low contrast means that the overall grayscale of the image is close, and the details are difficult to distinguish: the first preset voltage can be understood as a threshold voltage pre-set according to the sample characteristics, the type of detected particles and the system design requirements, which is used to limit the voltage range of the contrast adjustment electrode.

[0095] Specifically, the contrast adjustment electrode influences the trajectory of the probe particles and the distribution of their arrival at the detector by varying the magnitude and polarity of the applied voltage. When a positive voltage is applied, negatively charged probe particles are attracted, increasing their collection efficiency and boosting the signal strength in the corresponding area. When a negative voltage is applied, some particles are repelled, reducing the signal strength. By adjusting the external voltage applied to the lower electrode shoe 312, the signal differences between different areas on the detector can be altered, thereby adjusting the image contrast. The first preset voltage threshold is set to ensure that contrast adjustment is performed within a safe and effective range, avoiding excessive electric field distortion (manifested as a blurred image) caused by excessively high voltage.

[0096] For example, the first preset voltage is between -100 V and 100 V, and the sample stage 200 is grounded, which is 0 V. When a +50 V voltage is applied to the contrast adjustment electrode, the amount of secondary electrons collected in the raised areas of the sample surface is enhanced, making the raised areas appear brighter in the image, primarily manifesting as structural images. When a -50 V voltage is applied, secondary electron imaging is suppressed, and the signal electron source is primarily backscattered electrons, primarily manifesting as component images.

[0097] In an optional embodiment, the upper pole shoe 311 includes a magnetic insulating material, and the lower pole shoe 312 includes a first magnetic conductive material; the upper pole shoe 311 is in contact with the lower pole shoe 312 .

[0098] The magnetic permeability of the magnetic insulating material is greater than a second preset magnetic permeability threshold, and the magnetic permeability of the first magnetic conductive material is greater than or equal to a third preset magnetic permeability threshold; the second preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold; and the third preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold. The second preset magnetic permeability threshold can be understood as the minimum relative magnetic permeability required for the normal operation of the upper pole shoe 311; and the third preset magnetic permeability threshold can be understood as the minimum relative magnetic permeability required for the normal operation of the lower pole shoe 312.

[0099] Specifically, the upper pole shoe 311 is made of a magnetically permeable insulating material, while the lower pole shoe 312 is made of a magnetically permeable conductive material. The upper and lower pole shoes 311 and 312 form a seamless magnetic permeability channel, properly confining the magnetic field lines of the magnetic field generating unit 320 and facilitating the pole shoes' ability to optimize magnetic field distribution. Furthermore, the upper pole shoe 311 does not generate an electric field, reducing interference with the electron beam acceleration field and the magnetic field generating unit 320. Furthermore, the insulating properties of the upper pole shoe 311 prevent potential coupling between it and the lower pole shoe 312, ensuring that the lower pole shoe 312, when acting as a control electrode, is not interfered with by the upper pole shoe 311.

[0100] Exemplary insulating magnetic materials include, but are not limited to, ferrites, amorphous alloys, nanocrystalline soft magnetic alloys, and other composite materials or multilayer thin film structures. Magnetic conductive materials include, but are not limited to, pure iron, low-carbon steel, silicon steel sheets, Permalloy, nanocrystalline soft magnetic alloys, and other amorphous alloys.

[0101] In an optional embodiment, the upper pole shoe 311 includes a second magnetic conductive material, the lower pole shoe 312 includes a second magnetic conductive material, and the pole shoe 310 also includes an isolation structure (not shown in the figure) located between the upper pole shoe 311 and the lower pole shoe 312, and the isolation structure connects the upper pole shoe 311 and the lower pole shoe 312 respectively.

[0102] The magnetic permeability of the second magnetically permeable conductive material is greater than a fourth preset magnetic permeability threshold; the fourth preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold. The fourth preset magnetic permeability threshold can be understood as the minimum relative magnetic permeability required for the pole piece 310 to function properly when the upper pole piece 311 and the lower pole piece 312 are made of the second magnetically permeable conductive material and include an isolation structure therebetween.

[0103] Specifically, the upper pole shoe 311 is made of the second magnetically permeable conductive material, and the lower pole shoe 312 is made of the second magnetically permeable conductive material. The upper pole shoe 311 and the lower pole shoe 312 form a low-reluctance circuit, properly confining the magnetic lines of force of the magnetic field generating unit 320. Furthermore, the isolation structure (insulating film, insulating gasket, etc.) between the upper pole shoe 311 and the lower pole shoe 312 prevents potential coupling between the upper pole shoe 311 and the lower pole shoe 312, ensuring that the lower pole shoe 312 is not interfered with by the upper pole shoe 311 when acting as a control electrode.

[0104] In an optional embodiment, the isolation structure includes a magnetically permeable isolation structure;

[0105] The magnetic permeability of the magnetic isolation structure is greater than a fifth preset permeability threshold, which is greater than or equal to the first preset permeability threshold. The fifth preset permeability threshold can be understood as the minimum relative permeability required for the isolation structure to not affect the normal operation of the pole piece 310.

[0106] Specifically, to ensure that the magnetic resistance of the isolation structure does not become a bottleneck in the magnetic circuit and to avoid magnetic field leakage or gradient drop due to insufficient magnetic permeability, the isolation structure is made of magnetic permeable material, and the magnetic permeability of the magnetic permeable isolation structure is not less than a fifth preset magnetic permeability threshold.

[0107] Preferably, the magnetic isolation structure can use ferromagnetic insulating material as the insulating film. The magnetic permeability of the ferromagnetic insulating material can ensure the insulation effect between the lower pole shoe 312 and the upper pole shoe 311. At the same time, the insulating film made of ferromagnetic insulating material can effectively conduct magnetism, thereby reducing the degree of magnetic leakage of the objective lens, which is beneficial for the pole shoe 310 to play a role in optimizing the magnetic field distribution.

[0108] In an optional embodiment, the thickness d of the isolation structure satisfies 0.1 μm≤d≤50 μm.

[0109] Specifically, to ensure magnetic circuit performance, prevent the magnetic resistance of the isolation structure from becoming a bottleneck for the entire magnetic circuit, and avoid magnetic field leakage or gradient drop caused by insufficient magnetic permeability, the thickness of the isolation structure must be limited in addition to the selection of magnetic permeable materials. If the thickness is too thin, it will be difficult to effectively confine the magnetic field, which may easily overflow from the edges of the structure. Excessive thickness, however, will increase the overall magnetic resistance of the magnetic circuit. Based on the magnetic permeability of the selected isolation structure, the thickness d of the isolation structure must be at least 0.1μm and no more than 50μm.

[0110] Preferably, the thickness of the insulating film is 10 μm.

[0111] like Figure 2 As shown, in an optional embodiment, the at least one detector 400 includes a first detector 410, the first detector 410 is disposed between the lower pole shoe 312 and the electron emission module 100, and the first detector 410 is used to receive detection particles within a first reflection angle range;

[0112] And / or, at least one detector 400 includes a second detector 420, which is arranged between the sample stage 200 and the lower pole shoe 312; the second detector 420 is used to receive detection particles within a second reflection angle range; the second reflection angle range is smaller than the first reflection angle range.

[0113] The first reflection angle and the second reflection angle can be understood as the angles between the detection particles and the horizontal plane of the sample stage 200 after being reflected from the sample surface.

[0114] Specifically, the first detector 410 is used to detect surface structure information (such as surface roughness and defects) of the sample surface or near-surface carried by large-angle reflection particles; the second detector 420 is used to detect internal crystal structure information of the sample carried by small-angle reflection particles.

[0115] For example, the first detector 410 may be a backscattered electron detector, and the first reflection angle may be 45° to 90°. The second detector 420 may be a secondary electron detector, and the second reflection angle may be 0° to 45°.

[0116] With respect to the sample detection device provided in the above embodiments, the present invention further provides a sample detection method based on the device, which is applicable to any sample detection device in the above embodiments. Figure 3 This is a flow chart of a sample detection method provided by an embodiment of the present invention.

[0117] Based on this sample detection device, reference Figure 3 , the sample detection method may include the following specific steps:

[0118] S110 , controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles.

[0119] Specifically, the electron emission module generates an electron beam, which is accelerated by an accelerating voltage and focused into a thin beam by an electromagnetic lens. It bombards the sample to be tested on the sample stage along the axial direction, interacts with the sample atoms, and excites secondary electrons, backscattered electrons and other detection particles.

[0120] S120, adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles.

[0121] Specifically, the lower electrode acts as a control electrode when a voltage is applied, forming an axial electric field with the sample stage to adjust the imaging effect of the detected particles, such as adjusting image contrast, improving clarity, and reducing edge blur or ghosting.

[0122] S130 , receiving a detection signal fed back by the detector based on the detected particles and determining detection information of the sample to be tested according to the detection signal.

[0123] Specifically, the detector converts the received particle energy into a detection signal, and the processing module processes the detector signal to ultimately generate detection information reflecting the sample morphology, composition, or crystal orientation.

[0124] An embodiment of the present invention provides a sample detection method, which includes: controlling an electron emission module to emit an electron beam to a sample to be tested, so that the electron beam bombards the sample to be tested, and then directionally excites detection particles that carry characteristics such as the sample's surface morphology and composition. By adjusting the external voltage of the lower pole shoe, the lower pole shoe is reused as a control electrode to adjust the imaging effect of the detection particles, accelerate low-energy particles to improve collection efficiency, and adjust the detection signal ratio. The receiving detector determines the detection information of the sample to be tested based on the detection signal fed back by the detection particles and the detection signal, and finally completes the detection of the sample to be tested. The method provided by the embodiment of the present invention solves the problems of reduced signal collection efficiency and reduced imaging quality caused by traditional external control electrodes. By connecting the lower pole shoe to an external power supply to form an axial electric field, the motion trajectory of the detection particles is adjusted, and the signal reception efficiency and imaging quality are improved.

[0125] Figure 4 This is a flow chart of another sample detection method provided by an embodiment of the present invention. Based on the above sample detection device, refer to Figure 4 The present embodiment is a refinement of the above embodiment. Specifically, the above embodiment of "adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles" can be specifically refined to: adjusting the external voltage of the lower pole shoe to adjust the image contrast.

[0126] For details not yet provided in this embodiment, please refer to the previous embodiment.

[0127] like Figure 4 As shown, another sample detection method may include the following specific steps:

[0128] S210 , controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles.

[0129] S220: Adjust the external voltage of the lower pole shoe to adjust the image contrast.

[0130] Specifically, the lower electrode shoe acts as a contrast adjustment electrode when an external voltage is applied (voltage range -100V to 100V, preferably -50V to 50V), forming an axial electric field with the sample stage (grounded, 0V):

[0131] When a positive voltage is applied (the potential of the lower electrode shoe is higher than that of the sample stage), negatively charged detection particles (such as secondary electrons) are attracted and accelerated toward the detector, improving signal collection efficiency and enhancing the brightness contrast of surface details in the image;

[0132] When a negative voltage is applied (the potential of the lower electrode shoe is lower than that of the sample stage), low-energy particles are repelled, the secondary electron signal is suppressed, and the backscattered electrons become the main signal source, highlighting the differences in sample composition.

[0133] S230 , receiving a detection signal fed back by the detector based on the detected particles and determining detection information of the sample to be tested according to the detection signal.

[0134] Based on the above embodiments, the embodiment of the present invention further discloses a specific implementation method of using the lower pole shoe as a contrast adjustment electrode, and achieves contrast optimization by reusing part of the structure in the pole shoe.

[0135] In an optional embodiment, the detection information of the sample to be tested includes clarity;

[0136] After adjusting the external voltage of the lower pole shoe to adjust the image contrast, the following steps are also included:

[0137] The excitation current is adjusted based on the clarity to reduce the influence of external voltage adjustment on the electron beam.

[0138] Among them, clarity can be understood as the degree of discernibility of details in the image; the excitation current can be understood as the current flowing through the electromagnetic focusing module, and its size directly determines the magnetic field strength and distribution.

[0139] Specifically, the axial electric field generated by the external voltage applied to the lower pole shoe couples with the magnetic field of the electromagnetic focusing module, causing subtle interference with the magnetic field distribution and, in turn, reducing image clarity. Applying a positive voltage to the lower pole shoe enhances the edge effects of the magnetic field, altering the Lorentz force experienced by the electron beam at the edge, causing the beam spot to widen. Applying a negative voltage to the lower pole shoe can partially offset the magnetic field strength, causing the electron beam's focus center to shift. Furthermore, the electric field generated by the lower pole shoe exhibits a nonuniform distribution. Near the lower pole shoe (contrast adjustment electrode), equipotential lines are dense and the electric field strength varies dramatically. Near the center (i.e., away from the contrast adjustment electrode), equipotential lines are sparse and the electric field strength is relatively flat. This uneven electric field distribution results in different electric field forces acting on electrons at different positions and velocities as they pass through the lower pole shoe, making it difficult for them to form a common focus position, thus affecting electron beam resolution.

[0140] To solve this problem, the present application adjusts the excitation current to change the magnetic field generated by the electromagnetic focusing module (magnetic lens), specifically compensates for the interference of the electric field on the electron beam trajectory, and realizes the decoupling of the mutual interference between the electric field and the magnetic field.

[0141] For example, when acquiring a structural image, the secondary electron contrast is first enhanced by applying a positive voltage. At this time, the beam spot is expanded due to the positive voltage. The excitation current can be increased, the magnetic field strength can be enhanced, the electron beam track can be tightened, and the electric field interference can be compensated to ultimately achieve high-resolution imaging. When acquiring a compositional image, a negative voltage is applied to highlight the difference in element distribution. Then, the excitation current is synchronously adjusted to address the magnetic field offset caused by the negative voltage, and the electron beam path is corrected to improve the image resolution.

[0142] Figure 5 This is a flow chart of another sample detection method provided by an embodiment of the present invention. Figure 6 This is a schematic diagram of a scanning electron microscope of a sample to be tested provided by an embodiment of the present invention, with an accelerating electric field of 3 kV and a lower pole shoe connected to an external voltage of +100 kV. Figure 7 yes Figure 6 Schematic diagram of the scanning electron microscope of the sample to be tested after the magnetic field intensity and magnetic field gradient are increased synchronously. Based on the above sample detection device, reference Figure 5 The embodiment of the present invention is a refinement of the above embodiment. Specifically, in the above embodiment, "adjusting the external voltage of the lower pole shoe to adjust the image contrast" can be specifically refined as follows: reducing the external voltage of the lower pole shoe and simultaneously reducing the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the impact of the external voltage adjustment on the electron beam; or

[0143] The external voltage of the lower pole shoe is increased, and the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit are increased at the same time, so as to reduce the influence of the external voltage adjustment on the electron beam.

[0144] For details not yet provided in this embodiment, please refer to the previous embodiment.

[0145] like Figure 5 As shown, another sample detection method may include the following specific steps:

[0146] S310 , controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles.

[0147] S320. Lower the external voltage of the lower pole shoe, and at the same time reduce the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the impact of the external voltage adjustment on the electron beam; or increase the external voltage of the lower pole shoe, and at the same time increase the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the impact of the external voltage adjustment on the electron beam.

[0148] Among them, the magnetic field strength can be understood as the magnetic induction intensity generated by the magnetic field generating unit, which determines the magnitude of the Lorentz force exerted on the electron beam in the magnetic field; the magnetic field gradient can be understood as the rate of change of the magnetic field intensity along the propagation direction of the electron beam. In this application, it can specifically be the rate of change of the magnetic field intensity along the center of the electron beam outward (radial direction).

[0149] Specifically, there is a coupling effect between the axial electric field formed by the external voltage of the lower pole shoe and the magnetic field of the electromagnetic focusing module, which will cause weak interference to the magnetic field distribution and thus reduce the image clarity.

[0150] When a positive voltage is applied to the lower pole shoe, the magnetic field edge effect is enhanced, causing the Lorentz force acting on the electron beam at the edge region to change, widening the beam spot. When a negative voltage is applied to the lower pole shoe, the magnetic field strength may be partially offset, causing the electron beam focus center to shift. Furthermore, the electric field generated by the lower pole shoe exhibits a non-uniform distribution. Near the lower pole shoe (the contrast-adjusting electrode), the equipotential lines are dense and the electric field strength varies dramatically. Near the center of the electron beam (i.e., far from the lower pole shoe), the equipotential lines are sparse and the electric field strength is relatively flat. This uneven electric field distribution causes electrons at different positions and velocities to experience different electric field forces when passing through the lower pole shoe, making it difficult for them to form a common focus position, thus affecting the resolution of the electron beam. To solve this problem, the present application reduces the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit while reducing the external voltage of the lower pole shoe, so as to reduce the influence of the external voltage adjustment on the electron beam; or increases the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit while increasing the external voltage of the lower pole shoe, so as to reduce the influence of the external voltage adjustment on the electron beam.

[0151] For example, when the external voltage on the lower pole shoe is reduced, the negative voltage partially offsets the magnetic field strength, causing the focus center to shift. Simultaneously reducing the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit can make the magnetic field distribution more uniform, correct the focus position shift, and reduce the impact of external voltage adjustment on the electron beam.

[0152] Similarly, reference Figure 6 and Figure 7 When the external voltage of the lower pole shoe is increased, the forward voltage will enhance the edge effect of the magnetic field, causing the beam spot to expand. At this time, the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit also need to be increased synchronously to provide a stronger Lorentz force, tighten the electron beam path, and subject the edge electrons to a greater centripetal focusing force, thereby suppressing divergence and reducing the impact of external voltage adjustment on the electron beam.

[0153] S330 , receiving a detection signal fed back by the detector based on the detected particles and determining detection information of the sample to be tested according to the detection signal.

[0154] Based on the above embodiments, the embodiments of the present invention further disclose how to reduce the influence of external voltage adjustment on the electron beam by adjusting the magnetic field generating unit when the lower pole piece is used as a contrast adjustment electrode, thereby completing contrast adjustment while taking into account image clarity.

[0155] In an optional embodiment, S320, the external voltage of the lower pole shoe is reduced, and the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit are reduced to reduce the influence of the external voltage adjustment on the electron beam; or the external voltage of the lower pole shoe is increased, and the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit are increased to reduce the influence of the external voltage adjustment on the electron beam, which can be specifically refined as follows:

[0156] S321. Lower the external voltage of the lower pole shoe and reduce the excitation current at the same time to reduce the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit, and reduce the impact of the external voltage adjustment on the electron beam; or increase the external voltage of the lower pole shoe and increase the excitation current at the same time to increase the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit, and reduce the impact of the external voltage adjustment on the electron beam.

[0157] Specifically, for an axisymmetric magnetic lens, reducing the excitation current can reduce the magnetic field intensity and magnetic field gradient generated by the magnetic field generating unit, and increasing the excitation current can increase the magnetic field intensity and magnetic field gradient generated by the magnetic field generating unit.

[0158] Figure 8 This is a flow chart of another sample detection method provided by an embodiment of the present invention. Based on the above sample detection device, refer to Figure 8 The embodiment of the present invention is a refinement of the above embodiment. Specifically, after the above embodiment "controls the electron emission module to emit an electron beam to the sample to be tested so that the electron beam bombards the sample to be tested to generate detection particles", it also includes:

[0159] The external voltage of the lower pole shoe is adjusted to adjust the detection particle collection efficiency and / or collection ratio of the detector.

[0160] For details not yet provided in this embodiment, please refer to the previous embodiment.

[0161] like Figure 8 As shown, another sample detection method may include the following specific steps:

[0162] S410 , controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles.

[0163] S420: Adjust the external voltage of the lower pole shoe to adjust the detection particle collection efficiency and / or collection ratio of the detector.

[0164] Specifically, when the lower pole piece is connected to an external power source, it acts as a control electrode, forming an axial electric field with the sample stage. This axial electric field exerts a Coulomb force on probe particles (such as secondary electrons and backscattered electrons), further regulating their direction and velocity. For example, it accelerates low-energy secondary electrons toward the detector, adjusts the trajectory of probe particles, improves signal reception efficiency and imaging quality, or offsets trajectory deviations caused by the magnetic field, corrects the particle path, and reduces scattering noise.

[0165] S430, adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles.

[0166] S440 , receiving a detection signal fed back by the detector based on the detected particles and determining detection information of the sample to be tested according to the detection signal.

[0167] Based on the above embodiments, the embodiments of the present invention further disclose a method of how the sample detection device provided in this application adjusts the external voltage of the lower pole shoe to adjust the collection efficiency and / or collection ratio of the detector for detected particles. Without the need for additional independent electrodes, the collection efficiency and ratio of the detector for particles of different energies can be precisely controlled.

[0168] Figure 9 This is a flow chart of another sample detection method provided by an embodiment of the present invention. Figure 10 This is a schematic diagram of a scanning electron microscope of a sample to be tested provided by an embodiment of the present invention, in which the accelerating electric field is 3kV, the lower pole shoe is connected to 0V, and the detected particles are mainly secondary electrons. Figure 11 yes Figure 10 Schematic diagram of a scanning electron microscope of the sample to be tested, with the medium accelerating electric field being 3kV, the lower pole shoe connected to -135V, and the detected particles mainly being backscattered electrons.

[0169] Based on the above sample detection device, the detector includes a first detector. Figure 2 and Figure 9 The embodiment of the present invention is a refinement of the above embodiment. Specifically, in the above embodiment, "S420, adjusting the external voltage of the lower pole shoe to adjust the detection particle collection efficiency and / or collection ratio of the detector" can be specifically refined as follows: adjusting the external voltage of the lower pole shoe to be higher than the voltage of the sample stage to improve the detection particle collection efficiency of the first detector and increase the collection ratio of secondary electrons; or adjusting the external voltage of the lower pole shoe to be lower than the voltage of the sample stage to reduce the interference of secondary electrons on the first detector and increase the collection ratio of backscattered electrons.

[0170] For details not yet provided in this embodiment, please refer to the previous embodiment.

[0171] like Figure 9 As shown, another sample detection method may include the following specific steps:

[0172] S510 , controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles.

[0173] S520. Adjust the external voltage of the lower pole shoe to be higher than the voltage of the sample stage, thereby improving the detection particle collection efficiency of the first detector and increasing the collection ratio of secondary electrons; or, adjust the external voltage of the lower pole shoe to be lower than the voltage of the sample stage, thereby reducing the interference of secondary electrons on the first detector and increasing the collection ratio of backscattered electrons.

[0174] Specifically, refer to Figure 10 and Figure 11 The first detector is used to detect surface structural information (such as surface roughness and defects) on or near the sample surface carried by large-angle reflected particles. When the lower pole shoe voltage is higher than the sample stage, the generated axial electric field attracts negatively charged secondary electrons, accelerating them toward the first detector and improving the collection efficiency of secondary electrons to observe the surface morphology details of the sample. Conversely, when the lower pole shoe voltage is lower than the sample stage, the electric field repels low-energy secondary electrons, making it difficult for them to reach the first detector. However, high-energy backscattered electrons are less affected, thereby increasing the collection ratio of backscattered electrons and facilitating the analysis of element distribution differences on the sample surface.

[0175] S530, adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles.

[0176] S540: Receive a detection signal fed back by the detector based on the detected particles and determine detection information of the sample to be tested according to the detection signal.

[0177] Based on the above embodiments, the embodiment of the present invention further discloses a method for optimizing the collection efficiency and signal ratio of the first detector for secondary electrons and backscattered electrons by adjusting the external voltage of the lower pole shoe and utilizing the interaction between the axial electric field and the charge of the detected particles.

[0178] Figure 12 This is a flow chart of another sample detection method provided by an embodiment of the present invention. Figure 13 This is a schematic diagram of a scanning electron microscope of a sample to be measured provided by an embodiment of the present invention, with an accelerating electric field of 3kV, a lower pole shoe connected to 0V, and the shallow morphology of the sample surface. Figure 14 Figure 13 The middle accelerating electric field is 3kV, the lower pole shoe is connected to -250V, and the sample composition image is shown in the schematic diagram of the scanning electron microscope of the sample to be tested. Based on the above sample detection device, the detector includes a second detector. Figure 2 and Figure 12, the embodiment of the present invention is a refinement of the above embodiment. Specifically, in the above embodiment, "S420, adjust the external voltage of the lower pole shoe to adjust the detection particle collection efficiency and / or collection ratio of the detector" can be specifically refined as follows: adjust the external voltage of the lower pole shoe to be higher than the voltage of the sample stage, thereby improving the collection efficiency of the second detector for detection particles with a reflection angle less than a first preset reflection angle; or adjust the external voltage of the lower pole shoe to be lower than the voltage of the sample stage, thereby improving the collection efficiency of the second detector for detection particles with a reflection angle greater than a second preset reflection angle; the second preset reflection angle is greater than the first preset reflection angle; for the contents not yet fully detailed in this embodiment, please refer to the previous embodiment.

[0179] like Figure 12 As shown, another sample detection method may include the following specific steps:

[0180] S610 , controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles.

[0181] S620. Adjust the external voltage of the lower pole shoe to be higher than the voltage of the sample stage, thereby improving the collection efficiency of the second detector for detection particles with a reflection angle less than the first preset reflection angle; or adjust the external voltage of the lower pole shoe to be lower than the voltage of the sample stage, thereby improving the collection efficiency of the second detector for detection particles with a reflection angle greater than the second preset reflection angle; the second preset reflection angle is greater than the first preset reflection angle.

[0182] Specifically, refer to Figure 13 When the external voltage of the lower pole piece is adjusted to be higher than the sample stage voltage, the generated axial electric field attracts negatively charged probe particles. For probe particles with small reflection angles and trajectories close to the sample surface normal (such as secondary electrons), this electric field further accelerates their movement toward the second detector, reducing signal loss due to scattering or offset, thereby effectively improving imaging of shallow surface topography.

[0183] On the contrary, reference Figure 14 When the external voltage on the lower electrode shoe is adjusted to be lower than the sample stage voltage, the axial electric field repels the probe particles. At this point, probe particles with large reflection angles and away from the sample surface normal (such as backscattered electrons) have a better chance of overcoming the electric field repulsion and reaching the second detector, thereby obtaining depth information such as the element distribution on the sample surface.

[0184] S630, adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles.

[0185] S640: Receive a detection signal fed back by the detector based on the detected particles and determine detection information of the sample to be tested according to the detection signal.

[0186] Based on the above embodiments, the embodiment of the present invention further discloses a method for separating detection particles with different reflection angles through a second detector by adjusting the external voltage of the lower pole shoe.

[0187] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A sample detection device, characterized in that: include: an electron emission module, a sample stage, an electromagnetic focusing module, at least one detector, and a processing module; The emission module is used to emit electron beams; The sample stage is used to carry the sample to be tested, and the sample stage is located on the running path of the electron beam; the electron beam bombards the sample to be tested to generate detection particles; The electromagnetic focusing module is located on the running path of the detection particle and is used to adjust the motion state of the detection particle through the magnetic field and the electric field; The electromagnetic focusing module includes a pole shoe and a magnetic field generating unit, wherein the pole shoe partially surrounds the magnetic field generating unit; The magnetic field generating unit is used to adjust the motion state of the detection particles through the magnetic field; The pole shoe comprises an upper pole shoe and a lower pole shoe, the upper pole shoe is connected to the lower pole shoe and is electrically isolated from the lower pole shoe, and the magnetic permeability of the upper pole shoe and the lower pole shoe is greater than or equal to a first preset magnetic permeability threshold; The upper pole shoe and the lower pole shoe are used to jointly constrain the magnetic field generated by the magnetic field generating unit; The lower pole shoe serves as a control electrode when connected to an external power supply, and the control electrode is used to adjust the motion state of the detection particle through an electric field; The detector is used to receive the detection particles conditioned by the electromagnetic focusing module and generate a detection signal according to the detection particles; The processing module is connected to the detector and is used to determine the detection information of the sample to be tested according to the detection signal.

2. The sample detection device according to claim 1, characterized in that: The lower pole shoe serves as a contrast adjustment electrode when connected to an external power supply. The contrast adjustment electrode is used to adjust image contrast. The maximum voltage of the contrast adjustment electrode is less than a first preset voltage.

3. The sample detection device according to claim 1, characterized in that: The upper pole shoe comprises a magnetically conductive insulating material, and the lower pole shoe comprises a first magnetically conductive conductor material; The upper pole shoe is in contact with the lower pole shoe; In which, the magnetic permeability of the magnetic insulating material is greater than the second preset magnetic permeability threshold, the magnetic permeability of the first magnetic conductive material is greater than or equal to the third preset magnetic permeability threshold; the second preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold; the third preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold.

4. The sample detection device according to claim 1, characterized in that: The upper pole shoe comprises a second magnetically conductive material, the lower pole shoe comprises a second magnetically conductive material, and the pole shoe further comprises an isolation structure located between the upper pole shoe and the lower pole shoe, the isolation structure connecting the upper pole shoe and the lower pole shoe respectively; The magnetic permeability of the second magnetic conductive material is greater than a fourth preset magnetic permeability threshold; and the fourth preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold.

5. The sample detection device according to claim 4, characterized in that: The isolation structure includes a magnetic isolation structure; Wherein, the magnetic permeability of the magnetic isolation structure is greater than a fifth preset magnetic permeability threshold; the fifth preset magnetic permeability threshold is greater than or equal to the first preset magnetic permeability threshold.

6. The sample detection device according to claim 4, characterized in that: The thickness d of the isolation structure satisfies 0.1 μm≤d≤50 μm.

7. The sample detection device according to claim 1, characterized in that: At least one of the detectors includes a first detector, the first detector is arranged between the lower pole shoe and the electron emission module, and the first detector is used to receive the detection particles within a first reflection angle range; And / or, at least one of the detectors includes a second detector, which is arranged between the sample stage and the lower pole shoe; the second detector is used to receive the detection particles within a second reflection angle range; The second reflection angle range is smaller than the first reflection angle range.

8. A sample detection method, characterized in that: Applicable to the sample detection device according to any one of claims 1 to 7, wherein the detection method comprises: Controlling the electron emission module to emit an electron beam to the sample to be tested, so that the electron beam bombards the sample to be tested to generate detection particles; Adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles; A detection signal fed back by the detector based on the detection particles is received, and detection information of the sample to be tested is determined according to the detection signal.

9. The sample detection method according to claim 8, characterized in that: The lower electrode shoe serves as a contrast adjustment electrode when connected to an external power supply, and the maximum voltage of the contrast adjustment electrode is less than a first preset voltage; Adjusting the external voltage of the lower pole shoe to adjust the imaging effect of the detected particles includes: The external voltage of the lower pole shoe is adjusted to adjust the image contrast.

10. The sample detection method according to claim 9, characterized in that: Adjusting the external voltage of the lower pole shoe to adjust the image contrast includes: Lowering the external voltage of the lower pole shoe and reducing the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the influence of the external voltage adjustment on the electron beam; or, Increasing the external voltage of the lower pole shoe and increasing the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the influence of the external voltage adjustment on the electron beam; The magnetic field gradient is the difference between the magnetic field intensity value close to the axis where the electron beam is located and the magnetic field intensity value far from the axis where the electron beam is located.

11. The sample detection method according to claim 10, characterized in that: The method comprises: lowering the external voltage of the lower pole shoe and reducing the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the influence of the external voltage adjustment on the electron beam; or increasing the external voltage of the lower pole shoe and increasing the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit to reduce the influence of the external voltage adjustment on the electron beam, including: Lower the external voltage of the lower pole shoe and reduce the excitation current at the same time to reduce the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit, and reduce the impact of the external voltage adjustment on the electron beam; or increase the external voltage of the lower pole shoe and increase the excitation current at the same time to increase the magnetic field strength and magnetic field gradient generated by the magnetic field generating unit, and reduce the impact of the external voltage adjustment on the electron beam.

12. The sample detection method according to claim 11, characterized in that: The detection information of the sample to be tested includes clarity; After adjusting the external voltage of the lower pole shoe to adjust the image contrast, the method further includes: The excitation current is adjusted based on the definition to reduce the influence of the external voltage adjustment on the electron beam.

13. The sample detection method according to claim 9, characterized in that: After controlling the electron emission module to emit an electron beam to the sample to be tested so that the electron beam bombards the sample to be tested to generate detection particles, the method further includes: The external voltage of the lower pole shoe is adjusted to adjust the detection particle collection efficiency and / or collection ratio of the detector.

14. The sample detection method according to claim 13, characterized in that: The detector includes a first detector; Adjusting the external voltage of the lower pole piece to adjust the detection particle collection efficiency and / or collection ratio of the detector includes: Adjust the external voltage of the lower pole shoe to be higher than the voltage of the sample stage, thereby improving the detection particle collection efficiency of the first detector and increasing the collection ratio of secondary electrons; or, The external voltage of the lower pole shoe is adjusted to be lower than the voltage of the sample stage, thereby reducing the interference of the secondary electrons on the first detector and increasing the collection ratio of backscattered electrons.

15. The sample detection method according to claim 13, characterized in that: The detector includes a second detector; Adjusting the external voltage of the lower pole shoe to adjust the detection particle collection efficiency and / or collection ratio of the detector includes: Adjusting the external voltage of the lower pole shoe to be higher than the voltage of the sample stage to improve the collection efficiency of the second detector for detection particles with a reflection angle smaller than a first preset reflection angle; or, Adjusting the external voltage of the lower pole shoe to be lower than the voltage of the sample stage to improve the collection efficiency of the second detector for detection particles with a reflection angle greater than a second preset reflection angle; the second preset reflection angle is greater than the first preset reflection angle; The reflection angle is the angle between the detection particle and the horizontal plane where the sample stage is located.

Images