CN217847869U - Tungsten gun tip cathode, electron gun and scanning electron microscope - Google Patents
Tungsten gun tip cathode, electron gun and scanning electron microscope Download PDFInfo
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- CN217847869U CN217847869U CN202222334983.5U CN202222334983U CN217847869U CN 217847869 U CN217847869 U CN 217847869U CN 202222334983 U CN202222334983 U CN 202222334983U CN 217847869 U CN217847869 U CN 217847869U
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- 229910052721 tungsten Inorganic materials 0.000 title claims abstract description 55
- 239000010937 tungsten Substances 0.000 title claims abstract description 55
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title claims abstract description 53
- 238000010894 electron beam technology Methods 0.000 abstract description 22
- 238000002844 melting Methods 0.000 abstract description 7
- 230000008018 melting Effects 0.000 abstract description 7
- 150000003657 tungsten Chemical class 0.000 abstract 1
- 239000000523 sample Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 4
- 230000002035 prolonged effect Effects 0.000 description 4
- 239000002699 waste material Substances 0.000 description 3
- 230000004075 alteration Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000012876 topography Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Abstract
The utility model discloses a tungsten rifle point negative pole, electron gun and scanning electron microscope, this tungsten rifle point negative pole includes: a first extension portion; a second extension portion; the tip part is connected with the first extension part and the second extension part respectively, the cross-sectional area of the tip part is smaller than that of the first extension part, and the cross-sectional area of the tip part is smaller than that of the second extension part. The utility model discloses a tungsten rifle point negative pole is less than the cross-sectional area of first extension through the cross-sectional area of design pointed end portion, and the cross-sectional area of pointed end portion is less than the cross-sectional area of second extension to improve the emission performance of electron beam, reduced pointed end portion side high temperature melting's probability, improved the life of tungsten rifle point negative pole.
Description
Technical Field
The utility model belongs to scanning electron microscope part field, concretely relates to tungsten rifle point negative pole, electron gun and scanning electron microscope.
Background
Scanning electron microscopes are one of the large precision instruments for analyzing the topography of high resolution micro-regions, and have been widely used in the fields of detecting the surface topography, microstructure, energy spectrum, etc. of materials. The probe of a scanning electron microscope is an electron and the size of the electron source is typically on the order of microns or less. In the scanning process, electrons are generated from the heated cathode gun tip, and after the action of the multistage electric lens and the magnetic lens, an electron beam probe with high-frequency scanning is formed, so that the material information under the microscale is detected and analyzed.
The gun tip is a source of an electron probe, and the electron beam with small diameter and large current is one of the most important indexes for evaluating the performance of the gun tip. The thermal emission scanning electron microscope has a tip made of tungsten material, and its working principle is that the electron kinetic energy in the tip is greatly increased under high-temperature condition, and when the electron kinetic energy exceeds the work function of the cathode material surface, the electrons are emitted from the tip surface, so that a stable beam current is formed. To achieve a small diameter and high current electron beam current, the tip of the gun tip is typically very sharp and the operating temperature typically needs to reach about 2800K.
Since the velocity difference of emitted electrons is proportional to the temperature, the large velocity difference of electrons causes large aberration during imaging, thereby reducing the resolution. On the other hand, due to the evaporation effect of the lance tip surface, the lance tip will generally break after 50-100 hours of operation, which is not practical.
SUMMERY OF THE UTILITY MODEL
The present invention aims at solving at least one of the technical problems in the related art to a certain extent. Therefore, an object of the present invention is to provide a tungsten gun tip cathode, an electron gun and a scanning electron microscope. The utility model discloses a design the cross-sectional area of pointed end and be less than the cross-sectional area of first extension, and the cross-sectional area of pointed end is less than the cross-sectional area of second extension to improve the emission performance of electron beam, reduced the probability of pointed end side high temperature melting, improved the life of tungsten rifle point negative pole.
In a first aspect of the present invention, the present invention provides a tungsten gun tip cathode. According to an embodiment of the present invention, the tungsten gun tip cathode includes:
a first extension portion;
a second extension portion;
the tip hair fork is respectively connected with the first extension part and the second extension part, the cross-sectional area of the tip is smaller than that of the first extension part, and the cross-sectional area of the tip is smaller than that of the second extension part.
According to the tungsten gun point cathode of the embodiment of the present invention, when the current of the emitted beam is not changed, by designing that the cross-sectional area of the tip portion is smaller than the cross-sectional area of the first extension portion and the cross-sectional area of the tip portion is smaller than the cross-sectional area of the second extension portion, the tungsten gun point cathode is beneficial to emitting a narrower beam by the gun point, thereby enhancing the emission brightness of the electron beam and improving the emission performance of the electron beam; under the condition that the normal working temperature of the tip part is kept unchanged, the cross sectional area of the tip part is smaller than that of the first extending part, and the cross sectional area of the tip part is smaller than that of the second extending part, so that the current of the whole tungsten gun tip cathode is reduced, the probability of high-temperature melting of the side surface of the tip part is reduced, and the service life of the tungsten gun tip cathode is prolonged.
In addition, according to the tungsten gun point cathode of the above embodiment of the present invention, the following additional technical features can be provided:
in some embodiments of the present invention, a ratio of a cross-sectional area of the tip portion to a cross-sectional area of the first extension portion is (0.9-0.95): 1, and a ratio of a cross-sectional area of the tip portion to a cross-sectional area of the second extension portion is (0.9-0.95): 1.
In some embodiments of the invention, the tip portion has a cross-sectional area of 0.00635-0.0154 square millimeters, the first extension portion has a cross-sectional area of 0.00785-0.0177 square millimeters, and the second extension portion has a cross-sectional area of 0.00785-0.0177 square millimeters.
In some embodiments of the invention, the tip portion is symmetrical along a central axis of the tungsten gun tip cathode.
In some embodiments of the present invention, an included angle α between an extension line of the first extension portion along a first direction and an extension line of the second extension portion along a second direction is in a range of 10 ° to 30 °, the first direction is an extension direction of the first extension portion, and the second direction is an extension direction of the second extension portion.
In some embodiments of the present invention, a ratio of a length b of an orthographic projection of the first extension on the central axis of the tungsten-tip cathode to a length c of an orthographic projection of the tip portion on the central axis of the tungsten-tip cathode is 20-50.
In some embodiments of the present invention, the first extension has a length along the first direction of 9-11mm, and the second extension has a length along the second direction of 9-11mm.
In some embodiments of the present invention, the first extension has a cross-section that is rectangular, circular, or trapezoidal in shape; and/or the shape of the cross section of the second extension part is rectangular, round or trapezoidal; and/or the cross section of the tip part is rectangular, round or trapezoidal.
In a second aspect of the present invention, the present invention provides an electron gun, according to an embodiment of the present invention, the electron gun includes the tungsten gun point cathode of the above embodiments. Therefore, the emission performance of the electron gun is improved, the probability of high-temperature melting of the side surface of the tip part is reduced, and the service life of the electron gun is prolonged.
In a third aspect of the present invention, the utility model provides a scanning electron microscope, according to the utility model discloses an embodiment, scanning electron microscope includes above embodiment the electron gun. The scanning electron microscope has all the advantages of the electron gun, and is not described in detail herein.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic view of a tungsten gun tip cathode according to one embodiment of the present invention;
fig. 2 is a schematic view of an electron gun according to an embodiment of the present invention.
Reference numerals:
100-tungsten gun-tip cathode, 200-fixing frame, 300-Wechsler cap, 400-anode, 500-electron beam probe, 600-electron beam, 101-first extension part, 102-second extension part and 103-tip part.
Detailed Description
Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary intended for explaining the present invention, and should not be construed as limiting the present invention.
In an aspect of the present invention, the present invention provides a tungsten gun point cathode, referring to fig. 1, the tungsten gun point cathode includes: a first extension 101; a second extension 102; a tip part 103 connected to the first and second extension parts, respectively, and having a cross-sectional area smaller than that of the first extension part and smaller than that of the second extension part.
Under high temperature conditions, the electron kinetic energy of the tip portion is greatly increased, and when the work function of the surface is exceeded, electrons are emitted from the surface of the gun tip, so that a stable electron beam current is formed. The electron beam emission brightness is an index of the electron beam flow quality, the electron beam emission brightness is in direct proportion to the current of the electron beam and in inverse proportion to the cross-sectional area of the tip, and the working temperature is increased along with the increase of the current of the electron beam. Therefore, it is necessary to realize an electron beam having a diameter as small as possible on the premise of ensuring a beam current of an appropriate current.
According to the tungsten gun point cathode of the embodiment of the present invention, when the current of the emitted beam is not changed, the cross-sectional area of the tip portion is designed to be smaller than the cross-sectional area of the first extension portion, and the cross-sectional area of the tip portion is smaller than the cross-sectional area of the second extension portion, so that the gun point can emit a narrower beam, the emission brightness of the electron beam is enhanced, and the emission performance of the electron beam is improved; under the condition that the normal working temperature of the tip part is kept unchanged, the cross sectional area of the tip part is smaller than that of the first extending part, and the cross sectional area of the tip part is smaller than that of the second extending part, so that the current of the whole tungsten gun tip cathode is reduced, the probability of high-temperature melting of the side surface of the tip part is reduced, and the service life of the tungsten gun tip cathode is prolonged.
It should be noted that the cross section of the first extension portion refers to a plane of the first extension portion perpendicular to the first direction, the cross section of the second extension portion refers to a plane of the second extension portion perpendicular to the second direction, and the cross section of the tip portion refers to a plane of the tip portion perpendicular to a tangential direction of the tip portion.
According to some embodiments of the present invention, a ratio of a cross-sectional area of the tip portion to a cross-sectional area of the first extension portion is (0.9-0.95): 1, thereby limiting the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the first extension portion within the above range, ensuring that the tip portion can reach an operating temperature, and avoiding excessive temperatures of the first extension portion and the second extension portion. It can be understood that if the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the first extension portion is too small, the resistivity of the tip portion is large, and the temperature of the tip portion is too high under the same current condition; if the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the first extending portion is too large, the working temperature of the tip portion hardly reaches a predetermined value.
According to further embodiments of the present invention, the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the second extension portion is (0.9-0.95): 1, thereby limiting the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the second extension portion within the above range, ensuring that the tip portion can reach a normal operating temperature and avoiding excessive temperatures of the first extension portion and the second extension portion. It is understood that if the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the above-mentioned second extension portion is too small, the tip portion resistivity is large; if the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the second extension portion is too large, the working temperature of the tip portion hardly reaches a predetermined value.
According to still other embodiments of the present invention, the cross-sectional area of the tip portion is 0.00635-0.0154 square mm, the cross-sectional area of the first extension portion is 0.00785-0.0177 square mm, and the cross-sectional area of the second extension portion is 0.00785-0.0177 square mm, so that the cross-sectional area of the tip portion, the cross-sectional area of the first extension portion, and the cross-sectional area of the second extension portion are limited within the above ranges, thereby ensuring that the tip portion can reach a normal working temperature, and avoiding the temperature of the first extension portion and the second extension portion from being too high.
According to still other embodiments of the present invention, referring to fig. 1, the tip portion is symmetrical along the central axis of the tungsten gun tip cathode, so that the temperature on both sides of the tip portion is uniform, thereby reducing the probability of high temperature melting on both sides of the tip portion, and facilitating future quantitative production.
According to still other embodiments of the present invention, an included angle between an extension line of the first extension portion along a first direction and an extension line of the second extension portion along a second direction is α, an included angle α between an extension line of the first extension portion along the first direction and an extension line of the second extension portion along the second direction is 10 to 30 °, the first direction is the extension direction of the first extension portion, and the second direction is the extension direction of the second extension portion, so that the included angle α between the extension line of the first extension portion along the first direction and the extension line of the second extension portion along the second direction is set within a range of 10 to 30 °, thereby ensuring a requirement of a tip portion on electron beam emission performance and avoiding damage to the first extension portion and the second extension portion during operation. It can be understood that, the smaller the included angle between the extension line of the first extension portion along the first direction and the extension line of the second extension portion along the second direction is, the higher the surface electric field intensity of the tip portion is, thereby resulting in the stronger electric field intensity between the cathode and the anode and the stronger thermal electron emission capability of the tungsten gun tip cathode.
According to still other embodiments of the present invention, referring to fig. 1, the length of the orthographic projection of the first extending portion on the central axis of the tungsten gun point cathode is b, the length of the orthographic projection of the tip portion on the central axis of the tungsten gun point cathode is c, and the ratio of the length of the orthographic projection of the first extending portion on the central axis of the tungsten gun point cathode b to the length of the orthographic projection of the tip portion on the central axis of the tungsten gun point cathode c is 20-50. Therefore, the ratio of the length b of the orthographic projection of the first extension part on the central axis of the tungsten gun tip cathode to the length c of the orthographic projection of the tip part on the central axis of the tungsten gun tip cathode is limited in the range, the effective narrowing of the tip part is ensured, and the processing technology is prevented from being too complex.
According to still other embodiments of the present invention, the length of the first extending portion along the first direction is 9-11mm, so that the length of the first extending portion along the first direction is limited within the above range, thereby ensuring the normal operation of the tungsten gun tip cathode and avoiding the waste of tungsten metal material.
According to some embodiments of the present invention, the length of the second extending portion along the second direction is 9-11mm, so that the length of the second extending portion along the second direction is limited within the above range, thereby ensuring the normal operation requirement of the tungsten gun tip cathode and avoiding the waste of tungsten metal material.
In the embodiment of the present invention, the shape of the cross section of the first extending portion is not particularly limited, and may be selected by those skilled in the art according to actual requirements, and as a specific example, the shape of the cross section of the first extending portion is selected from a rectangle, a circle, and a trapezoid.
In some embodiments of the present invention, the shape of the cross section of the second extension is not particularly limited, and may be selected by those skilled in the art according to actual needs, and as a specific example, the shape of the cross section of the second extension is selected from a rectangle, a circle, and a trapezoid.
In some embodiments of the present invention, the shape of the cross section of the tip portion is not particularly limited, and may be selected by those skilled in the art according to actual needs, and as a specific example, the shape of the cross section of the tip portion is selected from a rectangle, a circle, and a trapezoid.
In a second aspect of the present invention, the present invention provides an electron gun, referring to fig. 2, including the tungsten gun point cathode 100, the fixing frame 200, the wecker cap 300, the anode 400, the electron beam probe 500 and the electron beam 600 as described in the above embodiments, wherein the tungsten gun point cathode is fixed by the fixing frame, and the anode is disposed under the tungsten gun point cathode and the wecker cap. When the working temperature of the tip part of the cathode of the tungsten gun tip reaches 2700-2800k, the electron kinetic energy in the gun tip is greatly increased, when the work function of the surface is exceeded, electrons are emitted from the surface of the gun tip, the two symmetrical and unconnected parts of the Vickers cap jointly inhibit the electron waste of the cathode of the tungsten gun tip, the anode is in positive pressure relative to the gun tip and is used for accelerating the electrons emitted by the cathode of the tungsten gun tip, and finally, an electron beam probe for high-frequency scanning is formed and is used for detecting material information under a microscopic scale. By arranging the tungsten gun tip cathode, the emission performance of the electron gun is improved, the probability of high-temperature melting of the side surface of the tip part is reduced, and the service life of the electron gun is prolonged.
In the third aspect of the utility model, the utility model provides a scanning electron microscope, according to the utility model discloses an embodiment, scanning electron microscope includes above-mentioned electron gun, and from this, above-mentioned scanning electron microscope has all advantages of above-mentioned electron gun, no longer gives unnecessary details here.
While embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations of the above embodiments may be made by those of ordinary skill in the art without departing from the scope of the present invention.
Claims (10)
1. A tungsten tip cathode, comprising:
a first extension portion;
a second extension portion;
and the tip hair fork is respectively connected with the first extension part and the second extension part, the cross-sectional area of the tip is smaller than that of the first extension part, and the cross-sectional area of the tip is smaller than that of the second extension part.
2. The tungsten gun tip cathode according to claim 1 wherein the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the first extension is (0.9-0.95): 1 and the ratio of the cross-sectional area of the tip portion to the cross-sectional area of the second extension is (0.9-0.95): 1.
3. The tungsten gun tip cathode of claim 2 wherein the cross-sectional area of the tip portion is 0.00635-0.0154 square millimeters, the cross-sectional area of the first extension portion is 0.00785-0.0177 square millimeters, and the cross-sectional area of the second extension portion is 0.00785-0.0177 square millimeters.
4. The tungsten gun tip cathode according to claim 1 wherein the tip portion is symmetrical along a central axis of the tungsten gun tip cathode.
5. The tungsten gun tip cathode according to claim 4, wherein an angle α between an extension line of the first extension portion in a first direction and an extension line of the second extension portion in a second direction is in a range of 10-30 °, the first direction being an extension direction of the first extension portion, and the second direction being an extension direction of the second extension portion.
6. The tungsten gun tip cathode according to claim 5, wherein a ratio of a length b of an orthographic projection of the first extension portion on the central axis to a length c of an orthographic projection of the tip portion on the central axis is 20-50.
7. The tungsten gun tip cathode according to claim 6, wherein the first extension has a length in the first direction of 9-11mm and the second extension has a length in the second direction of 9-11mm.
8. The tungsten gun tip cathode according to claim 6, wherein the first extension is rectangular, circular or trapezoidal in cross-section;
and/or the cross section of the second extension part is rectangular, round or trapezoidal;
and/or the cross section of the tip part is rectangular, round or trapezoidal.
9. An electron gun comprising a tungsten gun tip cathode as claimed in any one of claims 1 to 8.
10. A scanning electron microscope comprising the electron gun according to claim 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222334983.5U CN217847869U (en) | 2022-09-02 | 2022-09-02 | Tungsten gun tip cathode, electron gun and scanning electron microscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222334983.5U CN217847869U (en) | 2022-09-02 | 2022-09-02 | Tungsten gun tip cathode, electron gun and scanning electron microscope |
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| Publication Number | Publication Date |
|---|---|
| CN217847869U true CN217847869U (en) | 2022-11-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202222334983.5U Active CN217847869U (en) | 2022-09-02 | 2022-09-02 | Tungsten gun tip cathode, electron gun and scanning electron microscope |
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| CN (1) | CN217847869U (en) |
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- 2022-09-02 CN CN202222334983.5U patent/CN217847869U/en active Active
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Address after: 230088 floor 1-4, zone a, building E2, phase II, innovation industrial park, No. 2800, innovation Avenue, high tech Zone, Hefei, Anhui Province Patentee after: Guoyi Quantum Technology (Hefei) Co.,Ltd. Address before: 230088 floor 1-4, zone a, building E2, phase II, innovation industrial park, No. 2800, innovation Avenue, high tech Zone, Hefei, Anhui Province Patentee before: Guoyi Quantum (Hefei) Technology Co.,Ltd. |