Semi-closed secondary electron collector and scanning electron microscope thereof

Abstract

The utility model provides a semi-closed secondary electron collector and a scanning electron microscope thereof, the semi-closed secondary electron collector comprises a main body, a semi-closed cover plate and a grid mesh, the main body is hollow, and the inner surface of the main body is coated with a coating. The semi-closed secondary electron collector replaces a grid mesh, used for collecting and capturing secondary electrons, of a traditional secondary electron detector. According to the utility model, laser and other stray light appearing in a sample chamber of the scanning electron microscope can be shielded, the influence of the laser and the stray light on a secondary electron detector is reduced or even eliminated, the surface signal intensity is improved, and the optical measurement of a sample in the scanning electron microscope is realized.

Description

Technical Field

[0001] The utility model belongs to the field of scanning electron microscopes and ultrafast scanning electron microscopes, and particularly relates to a semi-enclosed secondary electron collector and a microscope thereof. Background Art

[0002] Scanning electron microscopes (SEMs) are widely used characterization instruments in scientific research and production. They primarily form images by collecting secondary electrons generated by the sample using a secondary electron detector. This detector typically consists of several components, including a grid, scintillator, light guide, and photomultiplier tube. In conventional SEMs, the photomultiplier tubes used in the secondary electron detectors are primarily sensitive to light in the visible to ultraviolet range, resulting in a SEM sample chamber that is completely shielded from external light.

[0003] With the development of instrumental science, the in-situ optical measurement technology of scanning electron microscopes and the emergence of ultrafast scanning electron microscopes have all required the introduction of external lasers into the sample chamber of the scanning electron microscope. The introduction of external lasers will generate serious noise in the secondary electron detector. After the laser enters the sample from the laser window of the sample chamber, it produces mirror reflection and diffuse reflection. After multiple reflections on the wall of the sample chamber, it enters the secondary electron detector and is finally amplified by the photomultiplier tube and participates in scanning imaging, resulting in a very low image signal-to-noise ratio. When a high-flux laser is used to irradiate the sample, it will cause the scanned image to be saturated. At the same time, other stray light sources (such as lights, ultraviolet rays, etc.) outside the sample chamber will also enter the secondary electron detector from the laser window, affecting the image signal-to-noise ratio. Therefore, traditional secondary electron detectors are difficult to apply to the scanning imaging of scanning electron microscope in-situ laser technology and ultrafast scanning electron microscopy. It is necessary to design a new type of secondary electron detector for detector laser shielding. Utility Model Content

[0004] Therefore, the purpose of the present invention is to overcome the shortcomings of the prior art and provide a semi-enclosed secondary electron collector and microscope thereof. The semi-enclosed secondary electron collector can reduce the impact of laser and other stray light sources on the scanned image. The semi-enclosed secondary electron collector prevents laser and stray light from directly penetrating the scintillator phosphor coating and entering the light guide, while allowing secondary electrons to enter the scintillator phosphor coating through a grid.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention provides a semi-enclosed secondary electron collector, which comprises: a main body, a semi-enclosed cover plate and a grid, wherein:

[0006] The main body is hollow and has a cylindrical or conical shape, and its inner surface is coated with a coating;

[0007] Preferably, the material of the coating is graphite; and / or

[0008] Preferably, the shapes of the upper and lower cross sections of the column or the vertebral body are the same or different.

[0009] According to the semi-enclosed secondary electron collector of the first aspect of the present utility model,

[0010] One side of the upper half of the main body is cut away to form a structure with one side concave and the other side convex, and the depth of the cut away is preferably 15 to 25 mm, more preferably 15 to 20 mm, and most preferably 15 mm;

[0011] The height of the main body is 20 to 100 mm, preferably 30 to 70 mm, most preferably 50 mm; and / or

[0012] The wall thickness of the main body is 0.5-5 mm, preferably 1-3 mm, and most preferably 1 mm.

[0013] According to the semi-enclosed secondary electron collector of the first aspect of the present invention, the shapes of the upper and lower cross sections are selected from one or more of the following: circular, square, elliptical, trapezoidal, rectangular, and triangular, preferably circular or elliptical, and most preferably circular.

[0014] According to the semi-enclosed secondary electron collector of the first aspect of the present invention, when the shapes of the upper and lower cross sections are circular:

[0015] The cross-sectional diameter of the upper and lower sections is 20 to 100 mm, preferably 30 to 70 mm, and most preferably 50 mm;

[0016] The diameter of the semicircle on one side of the semi-enclosed cover is 20 to 100 mm, preferably 30 to 70 mm, and most preferably 50 mm; and / or

[0017] The diameter of the semicircle on the other side of the semi-enclosed cover is 15-45 mm, preferably 25-35 mm, most preferably 30 mm, and is smaller than the diameter of the semicircle on one side.

[0018] According to the semi-enclosed secondary electron collector of the first aspect of the present invention, thin plates extending vertically upwards are respectively extended from both ends of the semicircular shape on one side;

[0019] Preferably, the thin plate is connected to the main body.

[0020] According to the semi-enclosed secondary electron collector of the first aspect of the present utility model,

[0021] The height of each thin plate at the junction with the main body is 5 to 20 mm, preferably 8 to 15 mm, most preferably 10 mm; and / or

[0022] The length of the junction between each thin plate and the semicircular portion on one side is 3 to 20 mm, preferably 5 to 15 mm, and most preferably 10 mm.

[0023] According to the semi-enclosed secondary electron collector of the first aspect of the present utility model,

[0024] The lower surface of the semi-enclosed cover plate is coated with a coating, and the material of the coating is preferably graphite; and / or

[0025] The main body or the semi-enclosed cover is made of brass or oxygen-free copper, and oxygen-free copper is most preferred.

[0026] According to the semi-enclosed secondary electron collector of the first aspect of the present invention, the grid comprises a metal bending wire;

[0027] Preferably, the number of the metal bending wires is 3 to 9, more preferably 4 to 6, most preferably 5; and / or

[0028] Preferably, the metal bending wire is made of brass or oxygen-free copper, most preferably oxygen-free copper.

[0029] According to the semi-enclosed secondary electron collector of the first aspect of the present utility model,

[0030] The diameter of the metal bending wire is 0.5 to 2 mm, preferably 0.8 to 1.5 mm, most preferably 1 mm; and / or

[0031] The diameter of the metal bending wire at its bent semicircle is the same as the length of the thin plate and the semicircle at one side, preferably 3 to 20 mm, more preferably 5 to 15 mm, and most preferably 10 mm.

[0032] A second aspect of the present invention provides a scanning electron microscope, which includes the semi-enclosed secondary electron collector described in the first aspect.

[0033] According to a specific embodiment of the present invention, the present invention provides a semi-enclosed secondary electron collector capable of shielding laser and stray light, the secondary electron collector comprising:

[0034] The main body is a hollow thin-walled cylinder, and the cross section of the cylinder is preferably circular;

[0035] The circular cross-section has a diameter of 20-100 mm, preferably 50 mm;

[0036] The column height is 20-100 mm, preferably 50 mm;

[0037] The cylinder wall thickness is 0.5-5 mm, preferably 1 mm;

[0038] The upper half of the column is cut off on one side, with a cutting depth of 15-25 mm, preferably 15 mm, forming a convex structure on one side after the cutting;

[0039] The semi-enclosed cover plate has a circular structure, and its diameter is consistent with the cross-sectional diameter of the main body;

[0040] The semi-enclosed cover has a 10mm semicircular opening on the outside, and thin plates (10mm high) extend vertically upward on both sides of the semicircular opening and are connected to the main body;

[0041] The grid is formed by bending five metal wires with a diameter of 1 mm, and the diameter of the semicircle is 10 mm, which is consistent with the size of the semicircular opening of the semi-enclosed cover;

[0042] The inner surface graphite coating is evenly coated on the inner surface of the semi-enclosed secondary electron collector using graphite conductive glue, which maintains conductivity while reducing the laser and stray light that enters the scintillator fluorescent coating after being reflected on the inner wall of the semi-enclosed secondary electron collector.

[0043] The purpose of this utility model is to provide a novel secondary electron collector for scanning electron microscope in-situ laser technology and ultrafast scanning electron microscopy imaging, capable of reducing the impact of laser and other stray light sources on the scanned image. The utility model has a semi-enclosed secondary electron collector, which prevents laser light and stray light from directly penetrating the scintillator phosphor coating and entering the light guide, while allowing secondary electrons to enter the scintillator phosphor coating through a grid.

[0044] According to another specific embodiment of the present invention, the present invention provides a semi-enclosed secondary electron collector, which includes: a main body, a semi-enclosed cover, a grid, and a graphite coating on the inner surface.

[0045] The main body is a hollow thin-walled cylinder, and the cross section of the cylinder is preferably circular;

[0046] The circular cross-section has a diameter of 20-100 mm, preferably 50 mm;

[0047] The column height is 20-100 mm, preferably 50 mm;

[0048] The cylinder wall thickness is 0.5-5 mm, preferably 1 mm;

[0049] The upper half of the column is cut off on one side, with a cutting depth of 5-20 mm, preferably 10 mm, forming a convex structure on one side after the cutting;

[0050] The semi-enclosed cover plate has a circular structure, and its diameter is consistent with the cross-sectional diameter of the main body;

[0051] The semi-enclosed cover has a 10mm semicircular opening on the outside, and thin plates (10mm high) extend vertically upward on both sides of the semicircular opening and are connected to the main body;

[0052] The grid is formed by bending five metal wires with a diameter of 1 mm, and the diameter of the semicircle is 10 mm, which is consistent with the size of the semicircular opening of the semi-enclosed cover;

[0053] The main body, semi-enclosed cover plate and grid can be made of brass or oxygen-free copper, with oxygen-free copper being preferred;

[0054] The inner surface graphite coating is evenly coated on the inner surface of the semi-enclosed secondary electron collector using graphite conductive glue, which maintains conductivity while reducing the laser and stray light that enters the scintillator fluorescent coating after being reflected on the inner wall of the semi-enclosed secondary electron collector.

[0055] The main body is connected to the semi-enclosed cover plate, and the semi-enclosed cover plate is glued to the semi-convex part of the main body with metal glue;

[0056] The semi-enclosed secondary electron collector is located at the front end of the scintillator fluorescent coating to block the pump laser and other stray light and prevent them from directly entering the scintillator fluorescent coating;

[0057] At the same time, a layer of graphite is coated on the inner surface of the semi-enclosed secondary electron collector to reduce the laser and stray light reflected from the inner wall into the scintillator fluorescent coating after entering the collector, thereby reducing their impact on the detector; a number of "fishhook"-shaped copper wires are connected to the highest point of the main body protrusion and the semi-circular opening of the semi-enclosed cover to form a grid, and an external +300V bias voltage is connected to attract secondary electrons to ensure normal secondary electron scanning imaging.

[0058] The utility model provides a semi-enclosed secondary electron collector, including a main body, a semi-enclosed cover, a grid, and a graphite coating on the inner surface. The semi-enclosed secondary electron collector is located at the front end of the secondary electron detector, replacing the grid used by the traditional secondary electron detector to collect and capture secondary electrons. The structure of the semi-enclosed secondary electron collector is similar to a cylinder, and one side of the upper half is cut off, and there is a semi-enclosed cover at the cut-off part to prevent laser and stray light from directly entering the scintillator fluorescent coating. At the same time, there is a graphite coating on its inner wall, which can further reduce the laser and stray light reflected from the opening into the inner wall and into the scintillator coating. A protruding grid is provided at the opening to collect secondary electrons. The utility model can shield the laser and other stray light appearing in the sample chamber of the scanning electron microscope, reduce or even eliminate the influence of the laser and stray light on the secondary electron detector, improve the surface signal intensity, and realize the optical measurement of the sample in the scanning electron microscope.

[0059] The semi-enclosed secondary electron collector of the present invention can have but is not limited to the following beneficial effects:

[0060] 1. The semi-enclosed secondary electron collector of the utility model acts on the traditional secondary electron detector and is used to replace the traditional grid-type Faraday cage. It has a simple structure, convenient material selection, low cost and easy processing, and is suitable for most models of scanning electron microscopes on the market.

[0061] 2. The semi-enclosed secondary electron collector of the utility model can shield the pump laser and other stray light while maintaining secondary electron imaging under normal circumstances, reducing their influence on the secondary electron detector, greatly improving the signal-to-noise ratio of the scanned image, and making it possible to introduce high-power laser into the scanning electron microscope sample chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings, wherein:

[0063] Figure 1 The figure shows a schematic structural diagram of the main part of the semi-enclosed secondary electron collector of the present invention.

[0064] Figure 2 A structural schematic diagram of the semi-enclosed cover of the semi-enclosed secondary electron collector of the utility model is shown; wherein, a is the diameter of the semicircle on the other side; b thin plate is the height of the connection with the main body; c thin plate is the length of the connection with the semicircle on one side.

[0065] Figure 3 The figure shows a structural diagram of the semi-enclosed secondary electron collector of the present invention.

[0066] Figure 4A schematic diagram of the working principle of the secondary electron collector in Example 1 of the present utility model is shown.

[0067] Figure 5 The figure shows an image of a laser-irradiated sample collected using the semi-enclosed secondary electron collector of the present invention.

[0068] Description of reference numerals:

[0069] 1. Main body; 2. Semi-enclosed cover; 3. Grid; 4. Coating. DETAILED DESCRIPTION

[0070] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. However, it should be understood that these embodiments are only used for more detailed and specific description and should not be understood as limiting the present invention in any form.

[0071] This section provides a general description of the materials and experimental methods used in the experiments of this utility model. Although many of the materials and operating methods used to achieve the objectives of this utility model are well known in the art, this utility model is described as detailed as possible. It will be clear to those skilled in the art that, unless otherwise specified, the materials and operating methods used in this utility model are well known in the art.

[0072] Example 1

[0073] This embodiment is used to illustrate the semi-enclosed secondary electron collector of the present invention.

[0074] The semi-enclosed secondary electron collector of the present invention comprises: a main body 1, a semi-enclosed cover plate 2 and a grid 3. The main body is hollow, and its inner surface is coated with a graphite coating, and the lower surface of the semi-enclosed cover plate 2 is coated with a graphite coating.

[0075] The main body 1 part is as follows Figure 1 As shown, the structure is cylindrical with a circular cross-section of 50 mm in diameter. One side of the upper portion is cut away, resulting in a structure with one side concave and the other side convex. The depth of the cutaway portion is 15 mm. The main body is 50 mm tall and has a thin wall of 1 mm. It can be made of brass or oxygen-free copper, with oxygen-free copper used in this embodiment.

[0076] The semi-enclosed cover plate 2 is as follows Figure 2As shown, the semi-enclosed cover plate 2 has a circular structure with a semicircular opening on the outside. Thin plates extend vertically upward on both sides of the semicircular opening. The diameter of the semicircular opening on one side of the semi-enclosed cover plate is 50 mm, while the diameter a of the semicircular opening on the other side is 30 mm, which is smaller than the diameter of the semicircular opening on one side. The thin plates are connected to the main body. The height b of each thin plate at the connection with the main body is 10 mm, and the length c at the connection with the semicircular opening on one side is 10 mm. The material is brass or oxygen-free copper. In this embodiment, oxygen-free copper is used.

[0077] like Figure 3 As shown, the main body 1 is connected to a semi-enclosed cover plate 2, which is bonded to the semi-convex portion of the main body with metal glue to block the pump laser and other stray light from directly entering the scintillator's phosphor coating. Simultaneously, a graphite coating 4 is applied to the inner surface to reduce reflection of the laser and stray light on the inner wall after entering the collector.

[0078] Grid 3 Figure 3 As shown, it is composed of several metal bending wires. In this embodiment, oxygen-free copper wires are used, numbering 5. The oxygen-free copper wires are bent and welded at the highest point of the main body protrusion and at the semicircular opening of the semi-enclosed cover. The diameter of the metal bending wire is 1 mm. The diameter of the metal bending wire at its bent semicircle is the same as the length c at the junction of the thin plate and the semicircular edge on one side, which is 10 mm.

[0079] At the same time, a +300V bias voltage is connected to attract secondary electrons. Figure 4 As shown, most of the laser light and stray light are reflected by the outer wall of the semi-enclosed secondary electron collector body 1 and the semi-enclosed cover 2, and cannot directly pass through the scintillator fluorescent coating and enter the light guide. At the same time, since the graphite coating 4 is attached to the inner wall of the semi-enclosed secondary electron collector, the small amount of pump laser and stray light entering the collector is difficult to pass through the scintillator coating and enter the light guide through reflection. The movement trajectory of the secondary electrons is regulated by the electric field of the sample chamber, and is attracted by the positive bias voltage of the grid 3 protruding from the front end of the semi-enclosed secondary electron collector and enters the collector. Then, it is attracted by the 10kV potential at the scintillator fluorescent coating, detours into the scintillator fluorescent coating, excites photons, and enters the photomultiplier tube through the light guide to amplify the signal, thereby obtaining a scanning image with a high signal-to-noise ratio. Figure 5 The figure shows an image of a laser-irradiated sample collected using the semi-enclosed secondary electron collector of the present invention.

[0080] Although the utility model has been described to a certain extent, it is obvious that appropriate changes in various conditions can be made without departing from the spirit and scope of the utility model. It is understood that the utility model is not limited to the embodiments described, but belongs to the scope of the claims, which includes equivalent replacements of each factor described.

Claims

1. A semi-enclosed secondary electron collector, characterized in that: The semi-enclosed secondary electron collector comprises: a main body, a semi-enclosed cover plate and a grid, wherein: The main body is hollow and has a cylindrical or pyramidal shape, and its inner surface is coated with a coating.

2. The semi-enclosed secondary electron collector according to claim 1, characterized in that: The material of the coating is graphite.

3. The semi-enclosed secondary electron collector according to claim 1, characterized in that: The shapes of the upper and lower cross sections of the column or the vertebral body are the same or different.

4. The semi-enclosed secondary electron collector according to claim 1, characterized in that: One side of the upper half of the main body is cut away to form a structure with one side concave and the other side convex; The height of the main body is 20 to 100 mm; and / or The wall thickness of the main body is 0.5-5 mm.

5. The semi-enclosed secondary electron collector according to claim 4, characterized in that: The depth of the resection is 15 to 25 mm; The height of the main body is 30 to 70 mm; and / or The wall thickness of the main body is 1 to 3 mm.

6. The semi-enclosed secondary electron collector according to claim 5, characterized in that: The depth of the resection is 15 to 20 mm; The height of the main body is 50 mm; and / or The wall thickness of the main body is 1 mm.

7. The semi-enclosed secondary electron collector according to claim 6, characterized in that: The depth of the resection was 15 mm.

8. The semi-enclosed secondary electron collector according to claim 3, characterized in that: The shapes of the upper and lower cross sections are selected from one or more of the following: circle, square, ellipse, trapezoid, and triangle.

9. The semi-enclosed secondary electron collector according to claim 8, characterized in that: The square is a rectangle.

10. The semi-enclosed secondary electron collector according to claim 8, characterized in that: The upper and lower cross sections are circular or elliptical in shape.

11. The semi-enclosed secondary electron collector according to claim 10, characterized in that: The upper and lower cross sections are circular in shape.

12. The semi-enclosed secondary electron collector according to any one of claims 3, 8 to 11, characterized in that: When the upper and lower cross-sections are circular: The cross-sectional diameters of the upper and lower sections are 20 to 100 mm; The diameter of the semicircle on one side of the semi-enclosed cover is 20 to 100 mm; and / or The diameter of the semicircle on the other side of the semi-enclosed cover is 15-45 mm, and is smaller than the diameter of the semicircle on one side.

13. The semi-enclosed secondary electron collector according to claim 12, characterized in that: The cross-sectional diameters of the upper and lower sections are 30 to 70 mm; The diameter of the semicircle on one side of the semi-enclosed cover is 30 to 70 mm; and / or The diameter of the semicircle on the other side of the semi-enclosed cover is 25-35 mm, and is smaller than the diameter of the semicircle on one side.

14. The semi-enclosed secondary electron collector according to claim 13, characterized in that: The cross-sectional diameter of the upper and lower sections is 50 mm; The diameter of the semicircle on one side of the semi-enclosed cover is 50 mm; and / or The diameter of the semicircle on the other side of the semi-enclosed cover is 30 mm, which is smaller than the diameter of the semicircle on one side.

15. The semi-enclosed secondary electron collector according to claim 12, characterized in that: Thin plates extend vertically upward from both ends of the semicircle on one side.

16. The semi-enclosed secondary electron collector according to claim 15, characterized in that: The thin plate is connected to the main body.

17. The semi-enclosed secondary electron collector according to claim 16, characterized in that: The height of each thin plate at the junction with the main body is 5 to 20 mm; and / or The length of the junction between each thin plate and the semicircle on one side is 3 to 20 mm.

18. The semi-enclosed secondary electron collector according to claim 17, characterized in that: The height of each thin plate at the junction with the main body is 8 to 15 mm; and / or The length of the junction between each thin plate and the semicircle on one side is 5 to 15 mm.

19. The semi-enclosed secondary electron collector according to claim 18, characterized in that: The height of each thin plate at the junction with the main body is 10 mm; and / or The length of the junction between each thin plate and the semicircle on one side is 10 mm.

20. The semi-enclosed secondary electron collector according to claim 1, characterized in that: The lower surface of the semi-enclosed cover plate is coated; and / or The main body or the semi-enclosed cover is made of brass or oxygen-free copper.

21. The semi-enclosed secondary electron collector according to claim 20, characterized in that: The material of the coating is graphite; and / or The main body or the semi-enclosed cover is made of oxygen-free copper.

22. The semi-enclosed secondary electron collector according to claim 1, characterized in that: The grid comprises metallic zigzag wires.

23. The semi-enclosed secondary electron collector according to claim 22, characterized in that: The number of the metal bending wires is 3 to 9; and / or The metal bending wire is made of brass or oxygen-free copper.

24. The semi-enclosed secondary electron collector according to claim 23, characterized in that: The number of the metal bending wires is 4 to 6; and / or The metal bending wire is made of oxygen-free copper.

25. The semi-enclosed secondary electron collector according to claim 24, characterized in that The number of the metal bending wires is 5.

26. The semi-enclosed secondary electron collector according to claim 22, characterized in that The diameter of the metal bending wire is 0.5-2 mm.

27. The semi-enclosed secondary electron collector according to claim 26, characterized in that The diameter of the metal bending wire is 0.8-1.5 mm.

28. The semi-enclosed secondary electron collector according to claim 27, characterized in that The diameter of the metal bending wire is 1 mm.

29. The semi-enclosed secondary electron collector according to claim 15, characterized in that The grid includes a metal bending wire, wherein the diameter of the metal bending wire at the bent semicircle is the same as the length of the connection between the thin plate and the semicircle on one side.

30. The semi-enclosed secondary electron collector according to claim 29, characterized in that The diameter of the metal bending wire at the bent semicircle is 3 to 20 mm.

31. The semi-enclosed secondary electron collector according to claim 30, characterized in that The diameter of the metal bending wire at the bent semicircle is 5 to 15 mm.

32. The semi-enclosed secondary electron collector according to claim 31, characterized in that The diameter of the metal bending wire at its bent semicircle is 10 mm.

33. A scanning electron microscope, characterized in that The scanning electron microscope comprises the semi-enclosed secondary electron collector according to any one of claims 1 to 32.

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