Test platform for resolution detection of scanning electron microscope

Abstract

The invention relates to the technical field of scanning electron microscope detection, in particular to a test platform for resolution detection of a scanning electron microscope. The test platform for resolution detection of the scanning electron microscope comprises a rack which is provided with an adapter plate, and a mounting hole is formed in the adapter plate in a penetrating manner; the sample chamber is provided with a containing cavity and a connecting part which are connected, the connecting part penetrates through the mounting hole to be mounted on the rack, a shielding layer is arranged on the bottom wall of the containing cavity, and the containing cavity is suitable for containing a lens cone of the scanning electron microscope; and the sample table is fixed on the bottom wall of the accommodating cavity through a connecting assembly. During testing, the sample table is directly fixed on the bottom wall of the sample chamber accommodating cavity through the connecting assembly, so that the interference of external vibration on the sample chamber and the sample table is reduced, and the influence of the external vibration on detection is reduced to the greatest extent; and the shielding effect of the bottom wall is improved due to the arrangement of the shielding layer on the bottom wall of the sample chamber accommodating cavity, so that the test platform fully isolates external vibration and electromagnetic interference, and the test result is more accurate.

Description

Technical Field

[0001] This invention relates to the field of scanning electron microscopy (SEM) inspection technology, and more specifically to a test platform for SEM resolution inspection. Background Technology

[0002] Scanning electron microscopes (SEMs), as important microscopic imaging devices, have wide applications in materials science, semiconductor testing, biomedicine, and nanotechnology. Their imaging resolution is a core indicator of equipment performance, directly affecting the precision and reliability of observation results. To achieve excellent imaging resolution, in addition to the electron optical design of the microscope tube itself, the testing and operating environment conditions are also crucial. The imaging process of an SEM is extremely sensitive to external vibrations and electromagnetic interference; even minor vibrations or magnetic field fluctuations can cause electron beam drift and image blurring, thus limiting its achievable resolution. Currently, common testing environments often fail to adequately isolate external vibrations and electromagnetic interference, resulting in test results that do not accurately reflect the design performance of the microscope tube. Therefore, in the research and development and production process, accurately and stably testing the limiting resolution of the microscope tube becomes a key aspect of evaluating and improving the overall performance of the SEM. Summary of the Invention

[0003] This invention provides a testing platform for scanning electron microscope resolution detection, which solves the problem that existing testing platforms cannot adequately isolate external vibrations and electromagnetic interference, thus affecting the accuracy of test results.

[0004] This invention provides a testing platform for scanning electron microscopy resolution detection, comprising:

[0005] The frame has an adapter plate with through mounting holes. The sample chamber has a receiving cavity and a connecting part connected together. The connecting part is mounted on the frame through a mounting hole. The bottom wall of the receiving cavity is provided with a shielding layer. The receiving cavity is suitable for accommodating the tube of the scanning electron microscope. The sample stage is fixed to the bottom wall of the receiving cavity via a connecting assembly.

[0006] Beneficial effects: During testing, the scanning electron microscope tube is fixed in the sample chamber, and the sample is placed on the sample stage. Because the sample stage is directly fixed to the bottom wall of the sample chamber via a connecting assembly, the interference caused by external vibrations to the sample chamber and sample stage is reduced, minimizing the impact of external vibrations on the detection. Furthermore, the shielding layer on the bottom wall of the sample chamber enhances the shielding effect. Therefore, the testing platform of this invention effectively isolates external vibrations and electromagnetic interference, resulting in more accurate test results.

[0007] In one optional embodiment, the connecting assembly includes a connecting post disposed at the bottom of the sample stage and a through hole disposed on the bottom wall of the receiving cavity, the connecting post being fixed in the through hole, and the bottom wall of the sample stage being in contact with the bottom wall of the receiving cavity.

[0008] The sample stage is directly connected to the sample chamber via a connecting column. The connection method is simple and reliable. The bottom wall of the sample stage is designed to contact the bottom wall of the receiving cavity, which not only increases the contact area between the two but also reduces the overall height of the machine and the volume of the vacuum chamber of the sample chamber, which is more conducive to reducing the interference of vibration on the test.

[0009] In one alternative embodiment, the shielding layer has at least two layers, and an isolation layer is provided between adjacent shielding layers.

[0010] Because the molecular pump generates a magnetic field, an isolation layer is set up to avoid a short circuit between the two shielding layers, which improves the accuracy of the test while ensuring the magnetic field shielding effect.

[0011] In one alternative embodiment, the frame is further provided with a molecular pump and a mounting plate, the mounting plate being located below the adapter plate, the molecular pump passing through an opening on the mounting plate, and a first vibration damping structure being provided between the sample chamber connection and the molecular pump.

[0012] The first vibration damping structure reduces the interference of vibrations generated by the molecular pump during operation on the sample chamber to a certain extent.

[0013] In one alternative implementation, a second vibration damping structure is provided between the adapter plate and the mounting plate.

[0014] The second vibration damping structure reduces the probability of external vibrations being transmitted to the sample chamber and sample stage through the adapter plate and mounting plate, further ensuring the accuracy of the test.

[0015] In one alternative embodiment, the molecular pump is provided with a side outlet, at which a shielding grid is provided.

[0016] To reduce the impact of the magnetic field generated by the molecular pump on the detection, a shielding grid is installed at the side outlet of the molecular pump. This not only provides electromagnetic shielding but also prevents foreign objects from falling in and affecting the normal operation of the test.

[0017] In one alternative embodiment, the sample stage includes a sample holder, an insulating base, and a displacement stage connected sequentially from top to bottom, with the displacement stage connected to the sample chamber by screws.

[0018] The screw-connected displacement stage and sample chamber offer higher rigidity compared to traditional cantilever beam designs, significantly reducing vibration interference and improving test stability. The insulating base between the sample holder and displacement stage facilitates the application of voltage to the sample holder, enabling operations requiring sample deceleration during some scanning electron microscope (SEM) viewing processes.

[0019] In one alternative embodiment, the sample holder is provided with a carbon-plated gold sample and a Faraday cup.

[0020] The carbon-sprayed gold sample and Faraday cup are placed on the sample holder, which can be used for scanning electron microscopy resolution imaging and beam current detection.

[0021] In one alternative implementation, the displacement stage comprises two stacked stages, with the two stages moving in perpendicular directions.

[0022] The two displacement stages allow the sample to move in the X and Y directions, ensuring smooth testing.

[0023] In one alternative embodiment, the sample chamber is further provided with an observation window, and the side of the observation window is provided with a shielding layer.

[0024] The addition of a shielding layer on the side of the observation window further enhances the overall shielding effect. Attached Figure Description

[0025] 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.

[0026] Figure 1 This is a schematic diagram of a test platform for scanning electron microscope resolution detection according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the sample chamber; Figure 3 for Figure 2 Another perspective illustration; Figure 4 This is a schematic diagram of the sample stage; Figure 5 This is a schematic diagram of the rack.

[0027] Explanation of reference numerals in the attached figures: 1. Frame; 101. Adapter plate; 102. Mounting plate; 2. Sample chamber; 201. Receiving cavity; 2011. Through hole; 202. Connecting part; 3. Sample stage; 301. Connecting column; 302. Sample holder; 303. Insulating base; 304. Displacement stage; 4. Molecular pump; 5. First vibration damping structure; 6. Second vibration damping structure; 7. Carbon-plated gold sample; 8. Faraday cup. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0029] The following is combined with Figures 1 to 5 Embodiments of the present invention are described.

[0030] According to an embodiment of the present invention, a test platform for scanning electron microscopy resolution detection is provided, comprising: The frame 1 has an adapter plate 101, on which mounting holes are provided through; The sample chamber 2 has a receiving cavity 201 and a connecting part 202 connected together. The connecting part 202 is mounted on the frame 1 through a mounting hole. A shielding layer is provided on the bottom wall of the receiving cavity 201. The receiving cavity 201 is suitable for accommodating the tube of the scanning electron microscope. The sample stage 3 is fixed to the bottom wall of the receiving cavity 201 by a connecting assembly.

[0031] like Figure 1 and Figure 5 As shown, the frame 1 in this embodiment is a cuboid frame welded from square steel. The orthographic projection of the adapter plate 101 is square, with a circular mounting hole in the center. It is made of marble because marble has the highest natural frequency. Of course, the frame 1 and adapter plate 101 can also be other shapes and materials, such as cylinders, circles, or alloys; no specific limitations are made here. The side walls of the sample chamber 2 are made of single-layer permalloy, and the bottom wall is made of double-layer permalloy. The receiving cavity 201 and the connecting part 202 are integrally formed, both being hollow cylindrical structures, and the inner diameter of the receiving cavity 201 is larger than the inner diameter of the connecting part 202. To facilitate the installation of the scanning electron microscope tube, the sample chamber 2 is also equipped with two pins with an included angle of 110°, which fix the microscope tube to the sample chamber 2. In addition, the sample chamber 2 is also equipped with functional interfaces such as the sample stage 3 geared motor feedthrough, the sample stage 3 feedthrough, a vacuum gauge, and a venting valve. To improve the evacuation speed, sample chamber 2 is equipped with four side evacuation ports, which are connected to a mechanical pump for evacuating the sample chamber 2.

[0032] Beneficial effects: During testing, the scanning electron microscope tube is fixed in the receiving cavity 201 of the sample chamber 2, and the sample is placed on the sample stage 3. Since the sample stage 3 is directly fixed to the bottom wall of the receiving cavity 201 of the sample chamber 2 through the connecting assembly, the interference caused by external vibration to the sample chamber 2 and the sample stage 3 is reduced, and the influence of external vibration on the detection is minimized. In addition, the shielding layer on the bottom wall of the receiving cavity 201 of the sample chamber 2 improves the shielding effect of the bottom wall. Therefore, the testing platform of the present invention fully isolates external vibration and electromagnetic interference, making the test results more accurate.

[0033] In one embodiment, the connecting assembly includes a connecting post 301 disposed at the bottom of the sample stage 3 and a through hole 2011 disposed on the bottom wall of the receiving cavity 201. The connecting post 301 is fixed in the through hole 2011, and the bottom wall of the sample stage 3 is in contact with the bottom wall of the receiving cavity 201.

[0034] like Figures 2 to 4 As shown, the bottom of the sample stage 3 is integrally formed with four connecting posts 301 along the circumference. Four through holes 2011 are correspondingly provided on the bottom wall of the receiving cavity 201. The diameter of the connecting posts 301 is the same as the inner diameter of the through holes 2011. The sample stage 3 is fixed to the sample chamber 2 by inserting the connecting posts 301 into the through holes 2011, and the bottom wall of the sample stage 3 is completely fitted against the bottom wall of the receiving cavity 201 to ensure complete contact. Of course, the number and distribution of the connecting posts 301 and through holes 2011 can be flexibly adjusted according to actual needs, and are not specifically limited here.

[0035] The sample stage 3 is directly connected to the sample chamber 2 via the connecting column 301. The connection method is simple and reliable. The bottom wall of the sample stage 3 is set to contact the bottom wall of the receiving cavity 201, which not only increases the contact area between the two, but also reduces the overall height of the machine and reduces the volume of the vacuum cavity of the sample chamber 2, which is more conducive to reducing the interference of vibration on the test.

[0036] In one embodiment, the shielding layer has at least two layers, and an isolation layer is provided between adjacent shielding layers.

[0037] In this embodiment, two shielding layers are provided. The number of shielding layers can also be three or more, which is not specifically limited here. The isolation layer is preferably a titanium plate, but can also be other metal plates that can play an isolation role, which is not specifically limited here.

[0038] Because the molecular pump 4 generates a magnetic field, an isolation layer is set up to avoid a short circuit between the two shielding layers, which improves the accuracy of the test while ensuring the magnetic field shielding effect.

[0039] In one embodiment, the frame 1 is also provided with a molecular pump 4 and a mounting plate 102. The mounting plate 102 is located below the adapter plate 101. The molecular pump 4 passes through the opening on the mounting plate 102. A first vibration damping structure 5 is provided between the connection part 202 of the sample chamber 2 and the molecular pump 4.

[0040] like Figure 1 As shown, the mounting plate 102 and the adapter plate 101 are arranged at intervals. The orthographic projection of the mounting plate 102 is also square. A molecular pump 4 is provided in the center of the mounting plate 102. A first vibration damping structure 5 is provided at the upper end of the molecular pump 4. In this embodiment, the first vibration damping structure 5 is a vibration isolator. The two ends of the vibration isolator are connected to the connection part 202 of the sample chamber 2 and the top end of the molecular pump 4 by threads. Of course, the first vibration damping structure 5 can also be in other forms, which are not specifically limited here.

[0041] The first vibration damping structure 5 reduces the interference of vibrations generated by the molecular pump 4 during operation on the sample chamber 2. Specifically, the vibration isolator can filter low-frequency environmental vibrations through elastic support, keeping the vibration amplitude of the sample stage 3 within the nanometer range and ensuring the stability of the relative position between the electron beam and the sample.

[0042] In addition, casters and support legs can be installed at the bottom of the frame 1. The casters facilitate the movement of the frame 1, and the support legs provide fixed support after the frame 1 is moved into place.

[0043] In one embodiment, a second vibration damping structure 6 is provided between the adapter plate 101 and the mounting plate 102.

[0044] In this embodiment, the second vibration damping structure 6 is an air spring. Four air springs are provided along the corners of the adapter plate 101 and the mounting plate 102. Of course, the second vibration damping structure 6 can also be in other forms, which are not specifically limited here.

[0045] The second vibration damping structure 6 reduces the probability of external vibrations being transmitted to the sample chamber 2 and sample stage 3 through the adapter plate 101 and mounting plate 102, further ensuring the accuracy of the detection. The air spring has a low natural frequency, which can effectively filter vibration sources that easily interfere with the sample stage 3, such as building resonance and low-frequency ground micro-movements. In addition, the stiffness of the air spring can be dynamically adjusted by regulating the internal air pressure. When the load increases, increasing the air pressure can maintain the spring's support height and elastic deformation stability. When the load decreases, decreasing the air pressure can avoid vibration transmission caused by over-constraint.

[0046] More importantly, the air spring and vibration isolator form a double-layer vibration reduction system, eliminating interference from different vibration sources on the sample stage 3 and the microscope barrel, providing an extremely stable mechanical environment for the detection of scanning electron microscope resolution. The air spring is located directly below the sample stage 3, acting as near-source vibration reduction, and can directly buffer the vibration energy transmitted to the sample stage 3; while the vibration isolator usually acts on the entire electron microscope frame 1, acting as global vibration reduction. The double buffer structure can reduce the coupling effect between the vibration of the frame 1 and the vibration of the sample stage 3, preventing the transmission of small vibrations of the frame 1 to the sample stage 3 through the structure. The molecular pump 4 ensures a high vacuum environment inside the microscope body, reducing electron beam scattering interference; the air spring ensures the mechanical stability of the sample stage 3, reducing the relative displacement between the electron beam and the sample. Together, they support the focusing accuracy of the electron beam, further restoring the limiting resolution of the scanning electron microscope.

[0047] In one embodiment, the molecular pump 4 is provided with a side outlet, and a shielding grid is provided at the side outlet.

[0048] To reduce the impact of the magnetic field generated by the molecular pump 4 on the detection, a shielding grid is installed at the side port of the molecular pump 4. This serves both electromagnetic shielding and prevention of foreign objects falling in and affecting the normal operation of the test. Specifically, when the molecular pump 4 performs pre-vacuuming through the side port, dust, sample debris, and condensable particles are easily introduced. Such foreign objects entering the molecular pump 4 can cause rotor blade or bearing wear, gap blockage, and dynamic balance failure. The shielding grid can efficiently intercept larger particles, reducing the amount of particles entering the pump body and lowering the failure frequency. After grounding, the shielding grid forms a Faraday cage-like structure, which can capture charged particles generated within the chamber due to various reasons, such as arcing or gas discharge, preventing them from bombarding the motor or control circuit of the molecular pump 4 and causing overcurrent, insulation breakdown, or signal interference. In addition, the shielding grid can evenly distribute the side-extraction airflow, avoiding pipe vibration and pressure fluctuations caused by local airflow impact; at the same time, in the event of a sudden pressure change (such as gas release or increased leakage rate), the airflow damping effect buffers the pressure impact, preventing high-pressure gas from instantly backflowing and damaging the rotor of the molecular pump 4, and ensuring the smoothness of the switch from pre-extraction to main extraction.

[0049] In one embodiment, the sample stage 3 includes a sample holder 302, an insulating base 303, and a displacement stage 304 connected sequentially from top to bottom. The displacement stage 304 is connected to the sample chamber 2 by screws.

[0050] like Figure 4As shown, the orthographic projection of the sample holder 302 is circular, and it is connected to the insulating base 303 by screws. The insulating base 303 is connected to the displacement stage 304 by screws. In this embodiment, the insulating base 303 is a ceramic base, but other materials can also be used, and no specific limitation is made here. The displacement stage 304 is made of a high-vacuum, completely non-magnetic material, such as oxygen-free copper, titanium alloy, high-purity aluminum, ceramic, etc. The reason is that the displacement stage 304 made of these materials does not generate stray magnetic fields, which can ensure that the electron beam is focused on the sample surface along the designed path, while eliminating coupling with the lens magnetic field and ensuring the stability of the lens system.

[0051] The displacement stage 304 and sample chamber 2 are connected by screws, which provides higher rigidity compared to the traditional cantilever beam design, significantly reducing vibration interference and improving test stability. The insulating base 303 between the sample holder 302 and the displacement stage 304 facilitates the application of voltage to the sample holder 302, enabling some operations requiring sample deceleration during scanning electron microscopy imaging.

[0052] In one embodiment, the sample holder 302 is provided with a carbon-plated gold sample 7 and a Faraday cup 8.

[0053] The carbon-sprayed gold sample 7 and the Faraday ring are located in the center of the sample holder 302. The carbon-sprayed gold sample 7 and the Faraday cup 8 can be used for scanning electron microscopy resolution imaging and beam detection.

[0054] In one embodiment, the displacement stage 304 comprises two stacked stages, and the movement directions of the two displacement stages 304 are perpendicular.

[0055] The two displacement stages 304 slide in different directions via slide rails and grooves, thereby driving the sample to move in the X and Y directions and ensuring the smooth progress of the test.

[0056] In one embodiment, the sample chamber 2 is further provided with an observation window, and the side of the observation window is provided with a shielding layer.

[0057] Because the glass material of the observation window lacks electromagnetic shielding capabilities, power frequency electromagnetic fields, radio frequency interference, and electrostatic fields outside the sample chamber can penetrate the sample chamber 2 through the observation window. These interferences can disrupt the electromagnetic lens system inside the electron microscope, causing electron beam deflection and defocusing, ultimately resulting in image drift and reduced resolution. The shielding layer reduces these external electromagnetic interferences, ensuring a stable electromagnetic field inside the sample chamber 2 and allowing the electron beam to be accurately focused on the sample surface. During scanning electron microscope operation, secondary electrons and backscattered electrons are generated inside the sample chamber 2. The shielding layer prevents increased detector noise caused by external signal crosstalk, improving the imaging signal-to-noise ratio. In summary, the shielding layer on the side of the observation window further enhances the overall shielding effect.

[0058] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A test platform for resolution detection in scanning electron microscopy, characterized in that, include: The frame (1) has an adapter plate (101) with mounting holes through it; The sample chamber (2) has a receiving cavity (201) and a connecting part (202) connected together. The connecting part (202) is installed on the frame (1) through the mounting hole. A shielding layer is provided on the bottom wall of the receiving cavity (201). The receiving cavity (201) is suitable for accommodating the tube of the scanning electron microscope. The sample stage (3) is fixed to the bottom wall of the receiving cavity (201) by a connecting assembly.

2. The test platform for scanning electron microscopy resolution detection according to claim 1, characterized in that, The connecting assembly includes a connecting post (301) at the bottom of the sample stage (3) and a through hole (2011) on the bottom wall of the receiving cavity (201). The connecting post (301) is fixed in the through hole (2011), and the bottom wall of the sample stage (3) is in contact with the bottom wall of the receiving cavity (201).

3. The test platform for scanning electron microscopy resolution detection according to claim 2, characterized in that, The shielding layer has at least two layers, and an isolation layer is provided between adjacent shielding layers.

4. The test platform for scanning electron microscopy resolution detection according to claim 1, characterized in that, The frame (1) is also provided with a molecular pump (4) and a mounting plate (102). The mounting plate (102) is located below the adapter plate (101). The molecular pump (4) passes through the opening of the mounting plate (102). A first vibration damping structure (5) is provided between the connection part (202) of the sample chamber (2) and the molecular pump (4).

5. The test platform for scanning electron microscopy resolution detection according to claim 4, characterized in that, A second vibration damping structure (6) is provided between the adapter plate (101) and the mounting plate (102).

6. The test platform for scanning electron microscopy resolution detection according to claim 4, characterized in that, The molecular pump (4) is provided with a side outlet, and a shielding grid is provided at the side outlet.

7. The test platform for scanning electron microscopy resolution detection according to any one of claims 1 to 6, characterized in that, The sample stage (3) includes a sample holder (302), an insulating base (303), and a displacement stage (304) connected from top to bottom. The displacement stage (304) is connected to the sample chamber (2) by screws.

8. The test platform for scanning electron microscopy resolution detection according to claim 7, characterized in that, The sample holder (302) is provided with a carbon-sprayed gold sample (7) and a Faraday cup (8).

9. The test platform for scanning electron microscopy resolution detection according to claim 7, characterized in that, The displacement stage (304) comprises two stacked stages, and the movement directions of the two displacement stages (304) are perpendicular.

10. The testing platform for scanning electron microscopy resolution detection according to any one of claims 1 to 6, characterized in that, The sample chamber (2) is also provided with an observation window, and the side of the observation window is provided with a shielding layer.

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