Sample stage for 3D STEM mode imaging of scanning electron microscope

Abstract

The invention discloses a sample stage for 3D STEM mode imaging of a scanning electron microscope. The device comprises a base, a bracket and a fixer, a clamping groove in the lower portion of the base is fixedly connected with a base arranged in a scanning electron microscope sample bin in an embedded mode, the support is fixedly installed on the base through a connecting piece, a plurality of step round holes are evenly distributed in the two sides of the support, the number of the fixers is two, the fixers are rotationally connected with the support respectively, and each fixer is provided with a plurality of rings. The number and the size of the circular rings are matched with the number and the size of the step circular holes, and when the fixator rotates to the horizontal position, the circular rings on the fixator are embedded into the step circular holes. The sample table can effectively fix the round carrying net and keep the round carrying net not deformed, and the number of times of repeated sample replacement is reduced; the embedded fixator can ensure that the sample table is in the optimal working distance, and meanwhile, scanning electron microscope 3D STEM mode imaging of a plurality of samples at a time is realized by utilizing a limited shooting space.

Description

Technical Field

[0001] The invention belongs to the technical field of scanning electron microscopes, and in particular relates to a sample stage for 3D STEM mode imaging of a scanning electron microscope. Background Art

[0002] Scanning electron microscope is easy to operate and can obtain the microstructure of materials. It has become the most common tool for microstructure observation and composition analysis of materials. The low voltage imaging mode of scanning electron microscope is conducive to the imaging of low atomic number samples, especially for polymer materials and biomaterials that are not resistant to electron beam irradiation and need to obtain better imaging contrast.

[0003] Scanning electron microscopes can now be equipped with accessories for shooting transmission electron detection mode (STEM). For samples that have been imaged by transmission electron microscopy, scanning transmission imaging can be achieved on the scanning electron microscope without re-sampling. 3D STEM mode imaging technology is the latest function developed by scanning electron microscopes. Usually, 3D STEM mode imaging requires a very small working distance of the sample stage, and more space needs to be left for the rotation and tilt of the sample stage. The 3D STEM mode shooting device currently configured for commercial scanning electron microscopes is usually a rectangular stage. This design is more conducive to the sample stage to ensure the optimal working distance, and to use the limited shooting space for dynamic rotation and tilting of the tilt angle range of -60°~60°, so as to realize the collection and imaging of the scattered electron signals of the sample. However, the sample stage currently used for 3D STEM imaging of scanning electron microscopes is to fix the circular grid by tightening the copper sheet with simple screws. The rigid contact between the copper sheet and the circular grid can easily cause the circular grid to fall and deform during the fixing process, which can cause serious damage to precious samples. At the same time, the copper sheet and the screws used to fix the copper sheet of the sample stage are also very easy to fall and lose during use, which limits the sustainable use of the sample stage. In particular, only two circular grids can be installed in one sample preparation, which greatly limits the efficiency of one-time imaging. Therefore, it is of great significance to develop a sample stage that can effectively fix multiple circular grids without disassembling the fixing components and realize dynamic multi-angle shooting of circular grids in a limited shooting space for 3D STEM shooting of scanning electron microscopes.

[0004] The Chinese invention patent application with publication number CN110071029A discloses a scanning electron microscope sample stage, including a base and at least one carrying module detachably connected to the base, wherein the carrying module has a carrying inclined surface for carrying samples. The invention does not require more complex components such as fixtures and rotating shafts, and can achieve the purpose of loading multiple samples at the same time and measuring multiple angles at the same time, and has both plane and cross-section testing functions, but the invention is not suitable for fixing circular grids photographed in the 3D STEM mode of scanning electron microscopes.

[0005] The Chinese invention patent application with publication number CN112454291A discloses a novel multifunctional composite variable scanning electron microscope (SEM) sample stage, including a sample stage base and a sample lifting platform; a fixed support connected to the SEM stage is provided at the center of the bottom of the sample stage base, the sample lifting platform is screwed into the threaded through hole of the base through an external thread, and a functional bracket is provided on the upper part of the sample stage base. This invention solves the problem that multiple small samples with obvious height differences cannot be observed at the same time, and solves the problem that multiple small samples are at the optimal working distance of the SEM at the same time during comprehensive analysis, but this invention is also not suitable for fixing the circular grid taken in the 3D STEM mode of the scanning electron microscope. Summary of the invention

[0006] In view of the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a sample stage for scanning electron microscope 3D STEM mode imaging, which is used to solve the problem of fixing the circular grid and improve the scanning electron microscope 3D STEM mode imaging efficiency. The sample stage of the present invention can effectively fix the circular grid and keep it from deforming, reducing the number of repeated sample replacements; the embedded fixture avoids the disassembly of the fixing component, and can ensure that the sample stage is at the optimal working distance while using limited shooting space to achieve scanning electron microscope 3D STEM mode imaging of multiple samples at a time.

[0007] The objectives of the present invention are achieved through the following technical solutions.

[0008] The present invention provides a sample stage for 3D STEM mode imaging of a scanning electron microscope, which comprises a base, a bracket and a fixture; a card slot is arranged below the base, the card slot is embedded and fixed with a base arranged inside a sample chamber of the scanning electron microscope, the bracket is fixedly installed on the base through a connecting piece, a plurality of stepped circular holes for placing a circular carrier grid are evenly distributed on both sides of the bracket, there are two fixtures, which are symmetrically arranged above the bracket and respectively form a rotational connection with the bracket, a plurality of circular rings are arranged on each fixture, the number and size of the circular rings match the number and size of the stepped circular holes, and when the fixture is rotated to a horizontal position, the circular rings on the fixture are embedded in the stepped circular holes.

[0009] In the present invention, through holes are correspondingly arranged at positions near the rotating connection on the fixer and the bracket, and a combination of a ball, a spring and a cylinder is built into the through hole on the bracket. The combination consists of independent balls, springs and cylinders. The spring is located between the ball and the cylinder, and the cylinder is arranged away from the fixer. The ball is located at the edge of the bracket near the fixer, so that the fixer can be fixed when it is rotated to the vertical direction through a spring snap connection.

[0010] In the present invention, the fixer and the bracket are rotationally connected via a rotating shaft.

[0011] In the present invention, balls are respectively arranged at the two ends of the bracket, and a slot is arranged at the top of the fixer, so that the fixer forms a fixed connection with the bracket when it is rotated to the horizontal direction; the balls are connected to a spring fixed on the bracket.

[0012] In the present invention, the fixer is a rectangular frame structure, support hooks are symmetrically arranged inside the rectangular frame, two circular holes are symmetrically arranged on each circular ring, and the rectangular frame is movably connected to the circular ring by the support hooks passing through the circular holes.

[0013] In the present invention, a hollow plate is provided on the fixture near the rotation connection with the bracket, so as to be used for inserting tweezers to guide the 90° rotational movement of the fixture between the vertical and horizontal directions.

[0014] In the present invention, two rings are arranged on each fixer.

[0015] In the present invention, the bracket is rectangular and the connecting piece is cylindrical.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1) The present invention utilizes the scanning electron microscope 3D STEM shooting process to ensure the sample stage needs the best working distance and effective rotation space, and designs an embedded integrally connected fixture; 2) The present invention provides a more stable support for the circular grid used for 3D STEM imaging of scanning electron microscope; 3) The present invention uses an in-situ erected or lowered fixture and a freely swaying ring to ensure that the fixed circular grid does not deform, which is of great significance for precious samples that can be used for both transmission electron microscopy and scanning electron microscopy 3D STEM imaging; 4) The present invention can place multiple samples at a time, reducing the number of times to replace samples. It is not necessary to disassemble parts each time a sample is placed, thereby increasing the service life of the sample stage and the efficiency of scanning electron microscope photography. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the device for observing the scanning transmission image of the present invention.

[0018] Figure 2 It is a schematic structural diagram of a device support for observing scanning transmission images of the present invention.

[0019] Figure 3 It is a schematic diagram of the structure of a fixture of the device for observing scanning transmission images of the present invention.

[0020] Figure 4 It is a structural schematic diagram of the connection between a fixture and a bracket of the device for observing scanning transmission images of the present invention.

[0021] Figure 5 It is a schematic top view of a device for observing a scanning transmission image according to the present invention.

[0022] Figure 6 It is a cross-sectional schematic diagram of a device for observing a scanning transmission image according to the present invention.

[0023] Numbers in the figure: 1-base, 11-first slot, 2-bracket, 21-step circular hole, 22-axial hole, 23-combination of ball, spring and cylinder, 231-cylinder, 232-spring, 233-first ball, 24-second ball, 3-fixer, 31-rotating shaft, 32-ring, 33-support hook, 34-second through hole, 35-hollow plate, 36-second slot, 4-connector. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] Example 1

[0026] like Figure 1-Figure 6 As shown, the present invention provides a sample stage for 3D STEM mode imaging of a scanning electron microscope, comprising a base, a base 1, a bracket 2, a fixer 3, a first slot 11, a rotating shaft 31, and a ring 32; the base is arranged inside a sample chamber of the scanning electron microscope, and a first slot 11 is provided under the base 1, and the base 1 and the base are embedded and fixed through the first slot 11.

[0027] The bracket 2 is connected and fixed to the base 1 via a connecting piece 4, which is a cylinder; there are two fixers 3, which are connected to the bracket 2 via a rotating shaft 31, and two rings 32 are installed inside each fixer 3.

[0028] The bracket 2 includes two stepped circular holes 21 on both sides. In a specific embodiment, the diameter of the fixed circular web is 3 mm. The stepped circular hole 21 is a step. The stepped circular hole 21 and the space that fits the diameter of the circular web can better support the circular web and prevent it from falling, so that the circular web can be placed horizontally. The through hole of the stepped circular hole 21 is used for the detector to perform scanning transmission imaging of the circular web. The edges of the two sides of the bracket 2 include an axial hole 22 and a first through hole. The first through hole has a built-in assembly 23 of a ball, a spring and a cylinder. In particular, if Figure 4 As shown, in the combination 23 of balls, springs and cylinders, the first ball 233, the spring 232 and the cylinder 231 are independent non-fixed combinations, the spring 232 is located between the first ball 233 and the cylinder 231, the diameter of the spring 232 is smaller than the first ball 233 and the cylindrical member 231, the cylindrical member 231 is arranged away from the fixture 3, and is used to block one end of the first through hole, the first ball 233 is located inside the edge of the bracket 2 close to the fixture 3; the second ball 24 is located at the center of the front end of the bracket 2, and is fixed to the bracket 2 by a spring.

[0029] The rectangular component of the fixer 3 includes a through-type rotating shaft 31, which is engaged with the axial hole 22 at the edge of the bracket 2, so that the fixer 3 can be erected or lowered around the axial hole 22 through the rotating shaft 31; the outer end of the rectangular component of the fixer 3 has a hollow plate 35 facing outward, and the hollow position thereof allows tweezers to pass through to apply force to the fixer 3, so that the fixer 3 can be erected or lowered; a second through hole 34 is provided on the fixer 3, and the first ball bearing that can be telescopically moved and the second through hole 34 provided on the edge of the fixer 3 can form a snap connection, which is used to maintain the stability of the 90° erection of the fixer 3.

[0030] The holder 3 fixes the circular ring 32 by means of the support hook 33, and the circular ring 32 can freely swing as the holder 3 is erected or lowered. In particular, when the holder 3 gradually descends to a horizontal position, the bottom end of the freely swinging circular ring 32 first contacts the circular grid and generates a relatively small contact force on the circular grid, thereby reducing the rigid contact between the circular ring 32 and the circular grid, and ensuring that the circular grid is not deformed; during the horizontal fixing process of the holder 3, the edge of the circular ring 32 is aligned with the edge of the circular grid directly above for pressing and fixing, and in particular, the hollow hole of the circular ring 32 is directly opposite to the through hole of the stepped circular hole 21, thereby maintaining the detector's collection and imaging of the scattered electron signal of the circular grid sample to the greatest extent; the top position of the outer rectangular frame of the holder 3 includes a second card slot 36, which is engaged with the second ball 24 of the bracket 2 that can move telescopically when the holder 3 descends, and further fixes the holder 3 in an embedded manner in the bracket 2, ensuring that the circular grid is fixed when the sample stage as a whole is tilted and rotated around the detector for shooting.

[0031] In a specific embodiment, for example, a polymer fiber sample is prepared on a circular grid with a diameter of 3 mm. After the circular grid is used for transmission electron microscopy, tweezers are directly used to pass through the hollow structure of the hollow plate 35 to apply force upward. The second through hole 34 of the fixture 3 and the first ball 233 in the assembly on the bracket 2 are connected through a ball buckle to keep the fixture 3 upright at 90 degrees. Tweezers are used to transfer the circular grid to the stepped circular hole 21 of the sample stage. Tweezers are used to pass through the hollow structure of the hollow plate 35 to apply force downward. The fixture 3 descends, and the ring 32 follows the fixture 3 to descend and shakes freely. The ring 32 The bottom end first contacts the circular grid and applies a relatively small contact force to it; further, the fixture 3 is placed completely horizontally, and the edge of the ring 32 is fixed to the corresponding edge of the circular grid directly above, and the hollow hole of the ring 32 is directly opposite to the through hole of the step circular hole 21, so as to maximize the collection and imaging of the scattered electron signal of the circular grid sample by the detector; at the same time, the second card slot 36 on the top of the fixture 3 is engaged and fixed with the second ball 24 of the bracket 2, so that the circular grid is completely pressed and fixed on the sample stage for subsequent scanning electron microscope 3D STEM mode imaging.

Claims

1. A sample stage for 3D STEM imaging in a scanning electron microscope, characterized in that: The invention comprises a base, a bracket and a fixture. A card slot is arranged under the base, the card slot is embedded and fixed with a base arranged inside a sample chamber of a scanning electron microscope, the bracket is fixedly installed on the base through a connecting piece, a plurality of stepped circular holes for placing a circular carrier net are evenly distributed on both sides of the bracket, there are two fixtures, which are symmetrically arranged above the bracket and respectively form a rotation connection with the bracket, a plurality of circular rings are arranged on each fixture, the number and size of the circular rings match the number and size of the stepped circular holes, and when the fixture is rotated to a horizontal position, the circular rings on the fixture are embedded in the stepped circular holes.

2. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: Through holes are correspondingly arranged at positions near the rotating connection on the fixture and the bracket. A combination of a ball, a spring and a cylinder is built into the through hole on the bracket. The combination consists of independent balls, springs and cylinders. The spring is located between the ball and the cylinder. The cylinder is arranged away from the fixture. The ball is located at the edge of the bracket near the fixture, so that the fixture can be fixed in the vertical direction through a spring snap connection.

3. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: The fixer and the bracket are rotatably connected via a rotating shaft.

4. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: Ball bearings are respectively arranged at the two ends of the bracket, and a slot is arranged at the top of the fixer, so that the fixer forms a fixed connection with the bracket when it is rotated to a horizontal direction; the ball bearings are connected to a spring fixed on the bracket.

5. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: The fixer is a rectangular frame structure, support hooks are symmetrically arranged inside the rectangular frame, two circular holes are symmetrically arranged on each circular ring, and the rectangular frame is movably connected to the circular ring by the support hooks passing through the circular holes.

6. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: A hollow plate is arranged on the fixture near the rotation connection with the bracket, so as to be used for inserting tweezers to guide the 90° rotation movement of the fixture between the vertical and horizontal directions.

7. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: Two rings are provided on each fixture.

8. The sample stage for 3D STEM imaging of a scanning electron microscope according to claim 1, characterized in that: The two sides of the bracket are rectangular, and the connecting piece is a cylinder.

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