A testing device and method for a hot field emission electron gun for a scanning electron microscope

Abstract

The application provides a testing device and method for a hot-field emission electron gun for a scanning electron microscope, and belongs to the technical field of electron microscope scanning. The testing device for the hot-field emission electron gun for the scanning electron microscope comprises an electron gun, a main body, a vacuum obtaining assembly, a fluorescent screen, a deflection structure, a vacuum gauge and a beam current meter. In the detection process, the electron gun is first placed in the detection space of the main body, the detection space is brought to a vacuum state through cooperation of a mechanical pump, a molecular pump and an ion pump, and then the performance of the hot-field emission electron gun for the scanning electron microscope is quantitatively evaluated through the fluorescent screen, the deflection structure, the vacuum gauge and the beam current meter, including neutral property, voltage resistance, brightness, beam deflection characteristics, current at an anode and beam current stability. Through the device, various performance tests can be performed on the electron gun, and the overall detection efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of electron microscopy scanning technology, and specifically to a testing device and method for a thermal field emission electron gun for scanning electron microscopes. Background Technology

[0002] The rapid development of technologies in life sciences, nanomaterials, and semiconductors has placed higher demands on the performance of scanning electron microscopes (SEMs). The electron gun, as a core component of the SEM, provides a stable electron beam, and its performance directly determines the various technical specifications of the SEM. An electron gun performance testing device is crucial for electron gun development, providing a stable vacuum environment for performance testing without interrupting the operation of the SEM.

[0003] The performance testing of electron guns includes mechanical performance, emission performance, and service life. Mechanical performance includes centering and pressure resistance; emission performance includes brightness, beam deflection, anode current, and beam stability.

[0004] Therefore, there is an urgent need for a testing device that can quantitatively evaluate the performance of thermal field emission electron guns used in scanning electron microscopes, including: neutrality, withstand voltage, brightness, beam deflection characteristics, anode current, and beam stability. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the deficiency in the existing electron gun performance testing that no single testing device can simultaneously test multiple performance characteristics, thereby providing a testing device and method for a thermal field emission electron gun for scanning electron microscopes.

[0006] To address the above problems, the present invention provides a testing apparatus for a thermal field emission electron gun for a scanning electron microscope, comprising:

[0007] An electron gun is suitable for emitting electron beams;

[0008] The main body has an internal detection space, which is suitable for accommodating the electron gun.

[0009] A vacuum acquisition component is connected to the detection space, and the vacuum acquisition component is adapted to perform vacuuming operations on the detection space;

[0010] A fluorescent screen is disposed within the detection space; the fluorescent screen is adapted to receive the electron beam emitted by the electron gun, and the fluorescent screen is adapted to display the diameter of the electron beam spot;

[0011] A deflection structure is disposed within the detection space, and the deflection structure controls the deflection of the electron beam by changing the magnetic field;

[0012] A vacuum gauge is installed within the detection space, and the vacuum gauge is adapted to monitor the vacuum level within the detection space in real time.

[0013] A beammeter is disposed within the detection space. The beammeter is adapted to receive the electron beam emitted by the electron gun and obtain the beam current value of the electron beam.

[0014] As a preferred embodiment, the beam meter includes:

[0015] A Faraday cup is disposed within the detection space, and the Faraday cup is used to collect the electron beam;

[0016] A picoammeter, adapted to be connected to the Faraday cup, the picoammeter being adapted to read the electron beam current value inside the Faraday cup;

[0017] A driving element, the end of which is connected to a Faraday cup; the driving element drives the Faraday cup to move within the detection space.

[0018] As a preferred embodiment, the vacuum acquisition component includes a first vacuum device and a second vacuum device; the first vacuum device is connected to the detection space via a first bypass pipe, and the second vacuum device is connected to the detection space via a second bypass pipe; the second bypass pipe is connected to the detection space, and the first bypass pipe is connected to the second bypass pipe.

[0019] As a preferred embodiment, the vacuum generating assembly further includes a first valve and a second valve; the first valve is disposed on the first bypass pipeline; the first valve is adapted to control the on / off state of the first vacuum device; the second valve is disposed on the second bypass pipeline, and the second valve is adapted to control the on / off state of the second vacuum device.

[0020] As a preferred option, it also includes:

[0021] A baking flange is connected to the main body; the baking flange is adapted to heat the detection space.

[0022] As a preferred embodiment, the first vacuum device includes a vacuum pump, and the second vacuum device includes a getter ion pump.

[0023] As a preferred option, it also includes:

[0024] A reflector is disposed on one side of the fluorescent screen; the reflector is adapted to reflect the image on the fluorescent screen.

[0025] As a preferred option, it also includes:

[0026] An anode flange is connected to the main body; the anode flange portion is located within the detection space and is connected to the anode of the electron gun.

[0027] To address the aforementioned problems, this invention provides a testing method for a thermal field emission electron gun for a scanning electron microscope, comprising the testing apparatus for a thermal field emission electron gun for a scanning electron microscope as described in any of the above-mentioned methods, and further comprising the steps of: firstly placing the electron gun to be tested in a detection space; subsequently, performing vacuum treatment on the detection space; and after the vacuum level in the detection space reaches a predetermined value, performing performance tests on the electron gun, specifically including neutrality testing, withstand voltage testing, brightness testing, beam deflection effect testing, anode current testing, and beam current stability testing.

[0028] As a preferred approach, in the performance testing of the electron gun, the centering is tested by adjusting the voltage and observing the change in the beam spot diameter on the fluorescent screen. If the beam spot wavers during the test, it indicates a problem with the coaxiality of the assembly and the centering of the electron beam. The withstand voltage is tested by energizing the electron gun and monitoring the change in vacuum level in the test space using a vacuum gauge. If the vacuum gauge reading changes during energization, it indicates a problem with the withstand voltage. The brightness is measured using a brightness value; the formula for the brightness value is... Where i b Here, d represents the electron beam current, α represents the virtual source diameter, and α represents the beam half-angle. The beam current is measured using a Faraday cup and a picoammeter. d is obtained through software, and α is derived by working distance and the diameter of the Faraday cup opening, thus obtaining the brightness value. The beam deflection characteristics are detected by adjusting the current in the deflection structure, thereby changing the magnetic field strength. The deflection and position of the electron beam are displayed on the fluorescent screen. By recording different magnetic field strengths and electron beam positions, the relationship between the deflection structure and the electron beam adjustment is determined, thus obtaining the beam deflection characteristics. The current at the anode is detected by constantly monitoring the picoammeter reading to ensure that the electron gun beam current meets the requirements for later use. The beam current stability is detected by monitoring the picoammeter reading and using the percentage of the difference between the maximum and minimum values ​​over a certain period of time as the calculation method.

[0029] The technical solution of this invention has the following advantages:

[0030] 1. This invention provides a testing device for a thermal field emission electron gun for scanning electron microscopy, comprising: an electron gun, a main body, a vacuum acquisition component, a fluorescent screen, a deflection structure, a vacuum gauge, and a beam meter. During testing, the electron gun is first placed within the testing space of the main body, and the vacuum acquisition component creates a vacuum in the testing space. Subsequently, the performance of the thermal field emission electron gun for scanning electron microscopy is quantitatively evaluated using the fluorescent screen, deflection structure, vacuum gauge, and beam meter, including: neutrality, withstand voltage, brightness, beam deflection characteristics, anode current, and beam stability. This device enables various performance tests on the electron gun and improves overall testing efficiency.

[0031] 2. The present invention provides a testing device for a thermal field emission electron gun for a scanning electron microscope, which further includes a Faraday cup, a picoammeter, and a driving component. The driving component drives the position of the Faraday cup, thereby enabling the picoammeter to detect the electron beam. When the picoammeter needs to detect the electron beam, the driving component drives the Faraday cup to move, moving the Faraday cup to the vicinity of the electron beam, so that the Faraday cup collects the electron beam and is detected by the picoammeter. When the picoammeter does not need to detect the electron beam, the driving component drives the Faraday cup away from the electron beam, and the electron beam falls normally onto the fluorescent screen.

[0032] 3. The present invention provides a testing device for a thermal field emission electron gun for a scanning electron microscope, wherein the vacuum acquisition component includes a first vacuum device and a second vacuum device. The first vacuum device performs a first vacuum operation on the detection space, and the second vacuum device performs a second vacuum operation on the detection space. The vacuum degree in the detection space is guaranteed to reach a predetermined value through the two vacuum operations.

[0033] 4. The testing device for a thermal field emission electron gun for a scanning electron microscope provided by the present invention further includes a baking flange. During the process of the vacuum acquisition component evacuating the detection space, the baking flange heats the detection space, and heating the detection space can further improve the vacuum degree in the detection space.

[0034] 5. The present invention provides a testing device for a thermal field emission electron gun for a scanning electron microscope, which further includes a reflector to reflect the image on the fluorescent screen, thereby facilitating the operator to observe the image on the fluorescent screen. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the test device for a thermal field emission electron gun for scanning electron microscope provided by the present invention.

[0037] Figure 2 This is a schematic diagram of the internal structure of a testing device for a thermal field emission electron gun for scanning electron microscope provided by the present invention.

[0038] Figure 3 for Figure 2 The enlarged view of point A shown.

[0039] Figure 4 The present invention provides a schematic diagram of the electron gun structure of a testing device for a thermal field emission electron gun for scanning electron microscopes.

[0040] Figure 5 The present invention provides a piping diagram of the vacuum acquisition component of a testing apparatus for a thermal field emission electron gun for scanning electron microscope.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Main body; 11. Detection space; 111. First detection space; 112. Second detection space; 12. Reflector; 2. Vacuum acquisition component; 21. First vacuum device; 22. First bypass pipeline; 23. Second bypass pipeline; 24. Second vacuum device; 3. Fluorescent screen; 4. Deflection structure; 5. Vacuum gauge; 6. Beammeter; 61. Faraday cup; 62. Pitot ammeter; 63. Drive unit; 7. Baking flange; 8. Anode flange; 9. Electron gun; 91. Cathode; 92. Grid; 93. Extraction electrode; 94. Focusing electrode; 95. Anode. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] like Figure 1As shown, the present invention provides a testing device for a thermal field emission electron gun 9 for scanning electron microscopes, comprising: an electron gun 9, a main body 1, a vacuum acquisition component 2, a fluorescent screen 3, a deflection structure 4, a vacuum gauge 5, and a beam meter 6; wherein the electron gun 9 is adapted to emit an electron beam; wherein the main body 1 has a detection space 11 inside, the detection space 11 being adapted to accommodate the electron gun 9; the vacuum acquisition component 2 is connected to the detection space 11, and the vacuum acquisition component 2 is adapted to perform vacuuming operations on the detection space 11; the fluorescent screen 3 is disposed within the detection space 11; the fluorescent screen 3 is adapted to receive the electron beam emitted by the electron gun 9, and the fluorescent screen 3 is adapted to display the diameter of the electron beam spot; the deflection structure 4 is disposed within the detection space 11, and the deflection structure 4 controls the deflection of the electron beam by changing the magnetic field; the vacuum gauge 5 is disposed within the detection space 11, and the vacuum gauge 5 is adapted to monitor the vacuum level within the detection space 11 in real time; the beam meter 6 is disposed within the detection space 11, and the beam meter 6 is adapted to receive the electron beam emitted by the electron gun 9 and obtain the beam current value of the electron beam.

[0048] like Figure 2 As shown, during the detection process, the electron gun 9 is first placed in the detection space 11 of the main body 1, and the detection space 11 is brought into a vacuum state by the vacuum obtaining component 2. Subsequently, the performance of the thermal field emission electron gun 9 for scanning electron microscopy is quantitatively evaluated by the fluorescent screen 3, deflection structure 4, vacuum gauge 5, and beam meter 6, including: neutrality, withstand voltage, brightness, beam deflection characteristics, current at the anode 95°, and beam current stability. This device can perform various performance tests on the electron gun 9 and improve the overall detection efficiency.

[0049] It should be noted that, in order to reduce the vacuuming time of the detection space 11 and minimize its volume, specifically, in this embodiment, the volume of the detection space 11 is the same as the volume of the electron gun 9, thereby minimizing the vacuuming time and improving efficiency.

[0050] It should be noted that the electron beam itself is invisible to the naked eye. By projecting the electron beam onto the fluorescent screen 3, the electron beam is made visible. In this embodiment, the fluorescent screen 3 is located at the bottom of the main body, and the electron beam emitted by the electron gun 9 directly irradiates the fluorescent screen 3.

[0051] like Figure 4As shown, it should be noted that the electron gun 9 includes a cathode 91, a grid 92, an extractor 93, a focusing electrode 94, and an anode 95. The cathode 91 emits electrons; the grid 92 controls the number of emitted electrons; the extractor 93 adjusts the emission current; the focusing electrode 94 changes the beam size; and the anode 95 accelerates the electrons. When the cathode 91 in the electron gun 9 is energized, the electrons pass sequentially through the cathode 91, grid 92, extractor 93, focusing electrode, and anode 95, after which the electron gun 9 emits an electron beam. The electron beam is received by the Faraday cup 61 and detected by the picoammeter 62. It should be noted that the cathode 91 is shaped like a filament and is energized at both ends.

[0052] It should be noted that the electron gun 9, main body 1, vacuum acquisition component 2, fluorescent screen 3, deflection structure 4, vacuum gauge 5, and beam meter 6 are all connected to the computer terminal. Their specific parameters and working status are controlled through the computer terminal, and the data obtained from their tests are also uploaded to the computer terminal to obtain the required detection data.

[0053] like Figure 3 As shown, the beammeter 6 further includes a Faraday cup 61, a picoammeter 62, and a drive unit 63. The Faraday cup 61 is disposed within the detection space 11 and is used to collect the electron beam. The picoammeter 62 is adapted to be connected to the Faraday cup 61 and is adapted to read the electron beam current value within the Faraday cup 61. The end of the drive unit 63 is connected to the Faraday cup 61, and the drive unit 63 drives the Faraday cup 61 to move within the detection space 11. The position of the Faraday cup 61 is driven by the driving element 63, thereby enabling the picoammeter 62 to detect the electron beam. When the picoammeter 62 needs to detect the electron beam, the driving element 63 drives the Faraday cup 61 to move, moving the Faraday cup 61 to the vicinity of the electron beam, so that the Faraday cup 61 collects the electron beam and is detected by the picoammeter 62. When the picoammeter 62 does not need to detect the electron beam, the driving element 63 drives the Faraday cup 61 away from the electron beam, and the electron beam falls normally onto the fluorescent screen 3.

[0054] It should be noted that the drive unit 63 is specifically a spiral linear guide, which can drive linearly in ultra-high vacuum and precisely control its position. It should also be noted that the drive unit 63 is connected to a computer terminal, which controls the movement distance and position of the drive unit 63, thereby achieving automatic control.

[0055] Furthermore, the vacuum acquisition component 2 includes a first vacuum unit 21 and a second vacuum unit 24. The first vacuum unit 21 is connected to the detection space 11 via a first bypass pipe 22, and the second vacuum unit 24 is connected to the detection space 11 via a second bypass pipe 23. The second bypass pipe 23 is connected to the detection space 11, and the first bypass pipe 22 is connected to the second bypass pipe 23.

[0056] It should be noted that the detection space 11 also includes a first detection space 111 and a second detection space 112. The first detection space 111 and the second detection space 112 are connected by a through hole. The size of the first detection space 111 is exactly the same as the size of the electron gun 9. The electron beam enters the second detection space 112 through the through hole. The fluorescent screen 3, deflection structure 4, vacuum gauge 5, beam meter 6, etc. are all set in the second detection space 112. The second detection space 112 is mainly used to detect the characteristics of the electron beam. It should be noted that the first detection space 111 is mainly used to house the electron gun 9, and the second detection space 112 is mainly used to detect the characteristics of the electron beam.

[0057] Furthermore, the vacuum obtaining component 2 also includes a first valve and a second valve; the first valve is disposed on the first bypass line 22; the first valve is adapted to control the on / off state of the first vacuum device 21; the second valve is disposed on the second bypass line 23, and the second valve is adapted to control the on / off state of the second vacuum device 24.

[0058] Furthermore, it also includes a baking flange 7, which is connected to the main body 1; the baking flange 7 is adapted to heat the detection space 11. During the vacuuming process of the vacuum obtaining component 2, the baking flange 7 heats the detection space 11, and heating the detection space 11 can further improve the vacuum degree in the detection space 11.

[0059] Furthermore, the first vacuum unit 21 includes a vacuum pump, i.e., a conventional mechanical pump, and the second vacuum unit 24 is a getter ion pump. The getter ion pump has a getter before it to adsorb reactive gases and an ion pump after it to adsorb inert gases. The total pumping speed can reach 100 L / s. The getter ion pump can further reduce the vacuum level within the detection space 11. It should be noted that the second vacuum unit 24 also includes a molecular pump, which is connected to the ion pump to further improve the gas absorption effect. In this scheme, the cooperation of the mechanical pump, molecular pump, and ion pump maintains a vacuum state in the detection space, enabling the inspection space to reach a supervacuum state, maximizing the accuracy of data during the detection process. This operation ensures that the vacuum level within the detection space 11 is better than 2 × 10⁻⁶. 8 torr.

[0060] It should be noted that in actual operation, the first vacuum device 21 and the first valve are opened first, and the detection space 11 is evacuated using the first vacuum device 21. When the vacuum level in the detection space 11 reaches the upper limit of the first vacuum device 21, the first vacuum device 21 and the first valve are closed, the second vacuum device 24 and the second valve are opened, and the baking flange 7 is started to bake and exhaust the air from the detection space 11. During this period, exhaust is carried out solely by the second vacuum device 24. This operation ensures that the vacuum level in the detection space 11 is better than 2×10⁻⁶. 8 It should be noted that the vacuum generating component 2 is connected to a computer terminal, which controls the starting and power of the first vacuum device 21, the first valve, the second vacuum device 24, the second valve, and the baking flange 7, thereby achieving automatic control and real-time monitoring of the specific working status.

[0061] Furthermore, a reflector 12 is included, which is disposed on one side of the fluorescent screen 3; the reflector 12 is adapted to reflect the image on the fluorescent screen 3. Specifically, in this embodiment, the electron beam of the electron gun 9 is emitted from top to bottom, and the fluorescent screen 3 is disposed at the bottom of the detection space 11, so the reflector 12 is disposed below the fluorescent screen 3, and the tilt angle of the reflector 12 can be adjusted to ensure that the operator can observe. It should be noted that in this solution, the main body 1 is disposed on a table, and in order to ensure the stability of the main body 1, fixing plates are respectively disposed on both sides of the main body 1, and the main body 1 is fixed to the table by the fixing plates.

[0062] Furthermore, it also includes an anode flange 8, which is connected to the main body 1; the anode flange 8 is partially located within the detection space 11 and is connected to the anode 95 of the electron gun 9. Specifically, the electron gun 9 is mounted on the anode flange 8.

[0063] It should be noted that the deflection structure 4 includes two sets of coils. Changing the current in the coils can change the magnetic field, thereby controlling the deflection of the electron beam. The two sets of coils are on the same axis, and the displacement can also be changed by superimposing the deflections.

[0064] Example 2

[0065] The testing method for a thermal field emission electron gun 9 for a scanning electron microscope includes a testing device for a thermal field emission electron gun 9 for a scanning electron microscope as described in Example 1, and further includes the following steps: first, placing the electron gun 9 to be tested in the detection space 11; then, evacuating the detection space 11; and when the vacuum level in the detection space 11 reaches a predetermined value, performing performance tests on the electron gun 9. The specific tests include neutrality testing, withstand voltage testing, brightness testing, beam deflection effect testing, current at the anode 95° testing, and beam current stability testing.

[0066] Furthermore, in the performance testing of the electron gun 9, the centering was tested by adjusting the voltage and observing the change in the beam spot diameter on the fluorescent screen 3. If the beam spot wavered during the test, it indicated a problem with the coaxiality of the assembly and the centering of the electron beam. The withstand voltage was tested by energizing the electron gun 9 and monitoring the vacuum level change in the detection space 11 using a vacuum gauge 5. If the value of the vacuum gauge 5 changed during the energization process, it indicated a problem with the withstand voltage. The brightness was measured using a brightness value; the formula for the brightness value is... Where i b The electron beam current is denoted by d, where d is the virtual source diameter and α is the beam half-angle. The beam current is measured using a Faraday cup 61 and a picoammeter 62. d is obtained through software, and α is derived by working distance and the diameter of the Faraday cup 61, thus obtaining the brightness value. The beam deflection characteristics are detected by adjusting the current of the deflection structure 4, thereby changing the magnetic field strength. The deflection and position of the electron beam are displayed on the fluorescent screen 3. By recording different magnetic field strengths and electron beam positions, the adjustment law between the deflection structure 4 and the electron beam is obtained, thus obtaining the beam deflection characteristics. The current at the anode 95 is detected by constantly monitoring the reading of the picoammeter 62 to ensure that the beam current of the electron gun 9 meets the requirements for later use. The beam current stability is detected by monitoring the reading of the picoammeter 62 and using the percentage of the difference between the maximum and minimum values ​​over a certain period of time as the calculation method.

[0067] It should be noted that during the vacuum acquisition process, such as Figure 5 As shown, the first vacuum device 21 and the first valve are first opened to evacuate the detection space 11. When the vacuum level in the detection space 11 reaches the upper limit of the first vacuum device 21, the first vacuum device 21 and the first valve are closed, the second vacuum device 24 and the second valve are opened, and the baking flange 7 is started to bake and exhaust the air from the detection space 11. During this period, exhaust is carried out solely by the second vacuum device 24. This operation ensures that the vacuum level in the detection space 11 is better than 2×10⁻⁶. 8 It should be noted that the vacuum generating component 2 is further connected to a computer terminal, which controls the starting and power of the first vacuum device 21, the first valve, the second vacuum device 24, the second valve, and the baking flange 7, thereby achieving automatic control and real-time monitoring of the specific working status.

[0068] It should be noted that the electron gun 9 has very high requirements for the coaxiality of the assembly during the centering test. The better the coaxiality, the better the emission performance. In order to verify the coaxiality of the assembly of the electron gun 9, the electron image is viewed on the fluorescent screen 3 of the device of the present invention. The diameter of the beam spot changes by adjusting the voltage of the focusing electrode 94. If the beam spot shakes a lot during the adjustment process, it indicates that the coaxiality of the assembly is poor, that is, the centering of the electron beam is poor.

[0069] It should be noted that in the withstand voltage test, the electron beam accelerating voltage of the scanning electron microscope (SEM) is between 0.2-30kV. If the surface roughness of the electron gun 9 components is insufficient or the assembly cleanliness is inadequate, arcing can easily occur under high voltage. Arcing will trigger the power supply protection, and the current to the cathode 91 will automatically shut off, affecting the progress of the SEM's use. Therefore, the withstand voltage of the components must be tested during the development of the electron gun 9. Using the device of this invention, the newly developed electron gun 9 is placed in the detection space 11, and high voltage is supplied to each electrode of the electron gun 9. At 30kV, the vacuum level in the detection space 11 is detected by the vacuum gauge 5. If the vacuum level suddenly deteriorates, it indicates that arcing exists in the gun chamber, and the surface roughness or assembly cleanliness of the electron gun 9 needs to be further improved.

[0070] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A testing apparatus for a thermal field emission electron gun for a scanning electron microscope, characterized in that, include: An electron gun (9) is suitable for emitting an electron beam; The main body (1) has a detection space (11) inside; A vacuum obtaining component (2) is connected to the detection space (11), and the vacuum obtaining component (2) is adapted to perform vacuuming work on the detection space (11); A fluorescent screen (3) is disposed within the detection space (11); the fluorescent screen (3) is adapted to receive the electron beam emitted by the electron gun (9), and the fluorescent screen (3) is adapted to display the diameter of the electron beam spot; A deflection structure (4) is disposed within the detection space (11), and the deflection structure (4) controls the deflection of the electron beam by changing the magnetic field; A vacuum gauge (5) is installed in the detection space (11), and the vacuum gauge (5) is adapted to monitor the vacuum level in the detection space (11) in real time; A beammeter (6) is disposed in the detection space (11). The beammeter (6) is adapted to receive the electron beam emitted by the electron gun (9) and obtain the beam current value of the electron beam. The beam meter (6) includes: A Faraday cup (61) is disposed within the detection space (11), the Faraday cup (61) being used to collect the electron beam; A picoammeter (62) is adapted to be connected to the Faraday cup (61), and the picoammeter (62) is adapted to read the electron beam current value inside the Faraday cup (61); A drive unit (63) is connected at one end to a Faraday cup (61); the drive unit (63) drives the Faraday cup (61) to move within the detection space (11); When the picoammeter (62) needs to detect the electron beam, the driving element (63) drives the Faraday cup (61) to move, moving the Faraday cup (61) to the vicinity of the electron beam, so that the Faraday cup (61) collects the electron beam and is detected by the picoammeter (62). When the picoammeter (62) does not need to detect the electron beam, the driving element (63) drives the Faraday cup (61) away from the electron beam, and the electron beam falls normally onto the fluorescent screen (3).

2. The testing apparatus for a thermal field emission electron gun for a scanning electron microscope according to claim 1, characterized in that, The vacuum acquisition component (2) includes a first vacuum device (21) and a second vacuum device (24); the first vacuum device (21) is connected to the detection space (11) through a first bypass pipe (22), and the second vacuum device (24) is connected to the detection space (11) through a second bypass pipe (23); the second bypass pipe (23) is connected to the detection space (11), and the first bypass pipe (22) is connected to the second bypass pipe (23).

3. The testing apparatus for a thermal field emission electron gun for a scanning electron microscope according to claim 2, characterized in that, The vacuum acquisition component (2) further includes a first valve and a second valve; the first valve is disposed on the first bypass line (22); the first valve is adapted to control the on / off state of the first vacuum device (21); the second valve is disposed on the second bypass line (23), and the second valve is adapted to control the on / off state of the second vacuum device (24).

4. The testing apparatus for a thermal field emission electron gun for a scanning electron microscope according to claim 3, characterized in that, Also includes: A baking flange (7) is connected to the main body (1); the baking flange (7) is adapted to heat the detection space (11).

5. The testing apparatus for a thermal field emission electron gun for a scanning electron microscope according to claim 4, characterized in that, The first vacuum device (21) includes a vacuum pump, and the second vacuum device (24) includes a getter ion pump.

6. The testing apparatus for a thermal field emission electron gun for a scanning electron microscope according to claim 1, characterized in that, Also includes: A reflector (12) is disposed on one side of the fluorescent screen (3); the reflector (12) is adapted to reflect the image on the fluorescent screen (3).

7. The testing apparatus for a thermal field emission electron gun for a scanning electron microscope according to claim 1, characterized in that, Also includes: An anode flange (8) is connected to the main body (1); a portion of the anode flange (8) is located within the detection space (11) and is connected to the anode (95) of the electron gun (9).

8. A test method for a thermal field emission electron gun used in scanning electron microscopy, characterized in that, The testing apparatus for a thermal field emission electron gun (9) for a scanning electron microscope according to any one of claims 1-7 further includes the steps of: firstly placing the electron gun (9) to be tested in a detection space (11); then performing a vacuum treatment on the detection space (11); and after the vacuum degree in the detection space (11) reaches a predetermined value, performing a performance test on the electron gun (9), specifically including the detection of neutrality, the detection of withstand voltage, the detection of brightness, the detection of beam deflection effect, the detection of current at the anode (95), and the detection of beam stability.

9. The testing method for a thermal field emission electron gun for scanning electron microscopy according to claim 8, characterized in that, In the performance test of the electron gun (9), the centering test is performed by adjusting the voltage and observing the change in the beam spot diameter on the fluorescent screen (3). If the beam spot shakes during the test, it indicates that there is a problem with the coaxiality of the assembly and the centering of the electron beam. The withstand voltage test is performed by energizing the electron gun (9) and monitoring the change in the vacuum level in the test space (11) through the vacuum gauge (5). If the value of the vacuum gauge (5) changes during the energization process, it indicates that there is a problem with the withstand voltage. Brightness is detected by measuring its value; the formula for the brightness value is: Where i b denoted as electron beam current, d is the virtual source diameter, and α is the beam half-angle; The beam current value is measured by the Faraday cup (61) and the picoammeter (62). d is obtained by inputting the corresponding electrode parameters in the electron optics simulation software to obtain the cross-spot diameter, which is the virtual source diameter. α is obtained by the working distance and the diameter of the Faraday cup (61), and then the brightness value is obtained. The beam deflection characteristics are detected by adjusting the current of the deflection structure (4) to change the magnetic field. The deflection and displacement of the electron beam will be displayed on the fluorescent screen (3). By recording different magnetic field magnitudes and the position of the electron beam, the adjustment law of the deflection structure (4) and the electron beam is obtained, and the beam deflection characteristics are obtained. The current at the anode (95) is detected by constantly monitoring the reading of the picoammeter (62) to ensure that the beam current value of the electron gun (9) can meet the needs of later use. The beam current stability is detected by monitoring the reading of the picoammeter (62) and using the percentage of the difference between the maximum and minimum values ​​and the average value within a certain period of time as the calculation method.

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