阅读说明：本技术 发射针结构、热场发射电子源及电子显微镜 (Emission needle structure, thermal field emission electron source and electron microscope ) 是由 郝占海 蔡素枝 陆梁 于 2021-03-03 设计创作，主要内容包括：本发明提供了一种发射针结构、热场发射电子源及电子显微镜,涉及电子显微镜技术领域,解决了氧化锆等低逸出功材料团易从发射针上脱落,影响电子源寿命的技术问题。该发射针结构位于电子源中发射电子,其包括针本体和低逸出功材料团,针本体的周壁上设置有容纳部,低逸出功材料团在烧结过程中形成有嵌入容纳部内的结合部位,且结合部位与容纳部的配合结构将低逸出功材料团夹固于针本体上。本发明的发射针结构能够将低逸出功材料团更为牢固的固定在针本体上,既能够增加储备氧化锆的数量,也能够增强低逸出功材料团与针本体结合的强度,防止低逸出功材料团脱落,延长了热场发射电子源的使用寿命。(The invention provides an emission needle structure, a thermal field emission electron source and an electron microscope, relates to the technical field of electron microscopes, and solves the technical problem that the service life of the electron source is influenced because low work function material clusters such as zirconia are easy to fall off from the emission needle. The emitting needle structure is positioned in an electron source to emit electrons and comprises a needle body and a low work function material mass, wherein an accommodating part is arranged on the peripheral wall of the needle body, a combining part embedded into the accommodating part is formed in the low work function material mass in the sintering process, and the low work function material mass is clamped on the needle body through a matching structure of the combining part and the accommodating part. The transmitting needle structure can firmly fix the low work function material group on the needle body, not only can increase the quantity of the stored zirconia, but also can enhance the bonding strength of the low work function material group and the needle body, prevent the low work function material group from falling off and prolong the service life of the thermal field emission electron source.)

1. An emission needle structure, located in an electron source to emit electrons, comprising a needle body and a bolus of low work function material, wherein:

the needle comprises a needle body and is characterized in that an accommodating part is arranged on the peripheral wall of the needle body, a bonding part embedded into the accommodating part is formed in the low work function material mass in the sintering process, and the low work function material mass is clamped on the needle body through a matching structure of the bonding part and the accommodating part.

2. The transmitting pin structure of claim 1, wherein the receiving portion is a groove or a hole, and the combining portion is filled in the groove or the hole.

3. The transmitting needle structure according to claim 1, wherein the accommodating portion is a groove recessed from a peripheral wall of the needle body in an axial direction thereof.

4. The transmission needle structure according to claim 3, wherein each of the grooves surrounds a circumferential wall of the needle body.

5. The transmission needle structure according to any one of claims 1 to 4, wherein the number of the receiving portions is two or more, and all the receiving portions are arranged at intervals in a length direction of the needle body.

6. The firing pin structure of any one of claims 1 to 4, wherein said low work function material bolus is ellipsoidal, has an extended length greater than the distribution of all said bonding sites on said pin body, and has an upper end completely surrounding said bonding site uppermost on said pin body and a lower end completely surrounding said bonding site lowermost on said pin body.

7. The transmission needle structure according to any one of claims 1 to 4, wherein the low work function material bolus is a zirconia bolus, and the zirconia bolus is disposed in the middle of the needle body and above the needle tip of the needle body so that the zirconia migrates to the needle tip of the needle body under the action of high temperature.

8. A thermal field emission electron source comprising the emission needle structure of any one of claims 1 to 7.

9. The thermal field emission electron source of claim 8, further comprising an insulator base, a suppressor, a terminal, a heating prong, and a suction electrode with a diaphragm, wherein:

the suppression electrode is a Schottky suppression electrode, and the suppression electrode is covered outside the insulating seat; all the binding posts penetrate through the insulating seat, one end of each binding post extends out of the insulating seat, the other end of each binding post is fixed with the heating hair fork, the needle body is fixed at the lower end of the heating hair fork and extends out of the suppression pole, and the center of the needle body is aligned to the center of the diaphragm.

10. An electron microscope comprising the thermal field emission electron source according to claim 8 or 9.

Technical Field

The invention relates to the technical field of electron microscopes, in particular to an emission needle structure, a thermal field emission electron source and an electron microscope.

Background

The electron microscope is a modern important scientific research, engineering observation and measurement instrument, and plays a great role in the scientific research fields of physics, materials, chemistry, life and the like, and the industrial fields of advanced semiconductor manufacturing process, engineering material detection and the like.

The electron source is one of its key components, and the characteristics of the electron source often determine the main performance of the electron microscope. Taking a scanning electron microscope as an example: the low-end scanning electron microscope uses a fork-type hot cathode (tungsten filament and lanthanum hexaboride) as an electron source, and the medium-end and high-end scanning electron microscopes use a cold field emission single-crystal tungsten and a thermal field emission zirconia-single-crystal tungsten electron source. The thermal field emission electron source has the characteristics of high brightness, large beam current, long service life, stable beam current and the like, and is most widely applied.

The zirconia at the tip of the thermal field emission electron source is attached to the surface of the emission needle so as to reduce the work function of electrons and facilitate electron emission; the zirconia on the emitter pin is gradually reduced as it evaporates/sublimates at high temperature, and therefore, a zirconia layer is generally provided on the emitter pin as a reserve zirconia source. Under the action of high temperature, the stored zirconia gradually migrates to the tip position to replenish the lost zirconia, and the electron emission can therefore last more than 8000 hours. When the stored zirconia is depleted or sloughed off, the electron source is terminated in life.

The applicant has found that the prior art has at least the following technical problems: the tip of the thermal field emission electron source is in a needle-shaped structure, and the zirconium oxide is coated on the emission needle in the needle-shaped structure; the combination firmness of the zirconia and the emission needle is low, the zirconia is easy to fall off from the emission needle in the use process, and when the zirconia falls off, the service life of the electron source is terminated, so that the service life of the electron source is greatly reduced.

Disclosure of Invention

The invention aims to provide an emission needle structure, a thermal field emission electron source and an electron microscope, which aim to solve the technical problem that the service life of the electron source is influenced because low work function material clusters such as zirconia and the like are easy to fall off from the emission needle in the prior art; the technical effects that can be produced by the preferred technical scheme in the technical schemes provided by the invention are described in detail in the following.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides an emission needle structure which is positioned in an electron source to emit electrons and comprises a needle body and a low work function material group, wherein:

the needle comprises a needle body and is characterized in that an accommodating part is arranged on the peripheral wall of the needle body, a bonding part embedded into the accommodating part is formed in the low work function material mass in the sintering process, and the low work function material mass is clamped on the needle body through a matching structure of the bonding part and the accommodating part.

Preferably, the accommodating part is a groove or a hole, and the combining part is filled in the groove or the hole.

Preferably, the housing is a groove recessed in the axial direction from the peripheral wall of the needle body.

Preferably, each of the grooves surrounds a circumferential wall of the needle body.

Preferably, the number of the accommodating parts is two or more, and all the accommodating parts are arranged at intervals along the length direction of the needle body.

Preferably, the low work function material bolus is ellipsoidal, the extended length of the work function material bolus is longer than the distribution length of all the binding sites on the needle body, the upper end of the work function material bolus completely wraps the binding site located at the uppermost position on the needle body, and the lower end of the work function material bolus completely wraps the binding site located at the lowermost position on the needle body.

Preferably, the low work function material group is a zirconia group, and the zirconia group is arranged in the middle of the needle body and located above the needle tip of the needle body, so that the zirconia migrates to the needle tip of the needle body under the action of high temperature.

The invention also provides a thermal field emission electron source which comprises the emission needle structure.

Preferably, the thermal field emission electron source further comprises an insulating base, a suppressor, a binding post, a heating hair-tine and an extraction pole having a diaphragm, wherein:

the suppression electrode is a Schottky suppression electrode, and the suppression electrode is covered outside the insulating seat; all the binding posts penetrate through the insulating seat, one end of each binding post extends out of the insulating seat, the other end of each binding post is fixed with the heating hair fork, the needle body is fixed at the lower end of the heating hair fork and extends out of the suppression pole, and the center of the needle body is aligned to the center of the diaphragm.

The invention also provides an electron microscope comprising the thermal field emission electron source.

Compared with the prior art, the emission needle structure, the thermal field emission electron source and the electron microscope provided by the invention have the following beneficial effects: the invention provides an emission needle structure, wherein a containing part is arranged on the circumferential wall of a needle body of a thermal field emission electron source, and a bonding part embedded in the containing part can be formed when a low work function material group is sintered on the needle body; the cooperation structure of the combining part and the accommodating part clamps the low work function material ball on the needle body; compared with a structure that the low work function material cluster is directly coated on the needle body, the transmitting needle structure can more firmly fix the low work function material cluster on the needle body, not only can increase the quantity of stored zirconia, but also can enhance the bonding strength of the low work function material cluster and the needle body, prevent the low work function material cluster from falling off, and prolong the service life of the thermal field emission electron source.

The thermal field emission electron source has the emission needle structure, so the service life of the thermal field emission electron source can be prolonged; the electron microscope of the invention also has the advantage of prolonged service life.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an overall schematic view of the structure of the emitter pin of the present invention;

FIG. 2 is a schematic cross-sectional view of a structure of a transmitting needle;

FIG. 3 is a perspective view of the needle body;

FIG. 4 is a front view of the needle body;

FIG. 5 is a schematic view showing the structure of a thermal field emission electron source of the present invention.

In figure 1, a needle body; 11. a trench; 2. zirconia clusters; 21. a binding site; 3. heating the hair fork; 4. an insulating base; 5. a Schottky suppressor electrode; 6. sucking out the pole; 61. a diaphragm; 7. and (4) binding posts.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "length", "width", "height", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "side", and the like, indicate orientations and positional relationships based on the orientations and positional relationships shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the equipment or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

The embodiment of the invention provides an emission needle structure which can enhance the bonding strength of low work function materials such as low zirconia and the like and a needle body, and prevent the low work function materials such as zirconia and the like from falling off and influencing the service life of an electron source.

The technical solution provided by the present invention is explained in more detail below with reference to fig. 1 to 5.

Example 1

As shown in fig. 1 to 5, the present embodiment provides an emission needle structure, located in an electron source, for emitting electrons, comprising a needle body 1 and a low work function material cluster, wherein:

the circumferential wall of the needle body 1 is provided with a containing part, the low work function material mass is formed with a combining part 21 embedded in the containing part in the sintering process, and the combining part 21 and the containing part are matched to clamp the low work function material mass on the needle body 1.

Among these, zirconia clusters 2 are generally used as the low work function material clusters, and zirconia will be exemplified below. The zirconia lumps 2 on the needle body 1 can be moved to the tip position of the needle body 1 during heating, and along with continuous heating, the zirconia lumps 2 are continuously moved to the tip to continuously supplement lost zirconia, so that the electron work function is reduced.

Thermionic emission is the heating of an object to a sufficiently high temperature that electrons within the object increase in energy with increasing temperature, wherein a portion of the electrons reach an energy sufficient to overcome their barrier to escape, i.e., work function, from within the object into a vacuum. In this embodiment, the surface of the needle body 1 is coated with the low work function material such as the zirconia cluster 2, so that the initial temperature at which the thermal emission electron source starts to emit electrons can be reduced, and the thermal emission efficiency of the thermal emission electron source can be improved. The needle body 1 is generally made of single crystal tungsten.

In the transmitting needle structure, zirconia as a low work function material is in a bulk shape, and a bonding part 21 formed by zirconia lumps 2 in the sintering process is matched with an accommodating part, so that the zirconia lumps 2 are clamped on a needle body 1; compared with the structure that the zirconia lumps 2 are directly coated on the needle body 1, the launching needle structure can more firmly fix the low work function material lumps on the needle body 1.

Since the zirconia grains 2 have a part (the part is the above-mentioned joint portion 21) fitted in the accommodating portion, this structure can increase the amount of the reserve zirconia compared with the zirconia grains 2 having the same size, and the amount of the zirconia fitted in the accommodating portion is larger than that when the zirconia grains 2 are directly coated on the needle body 1. Meanwhile, the bonding strength of the low work function material group and the needle body 1 can be enhanced, the low work function material group is prevented from falling off, and the service life of the thermal field emission electron source is prolonged.

In order to further increase the storage amount of zirconia and improve the bonding strength between the zirconia grains 2 and the needle body 1, the accommodating portion may be a groove or a hole, and the bonding portion 21 of the zirconia grains 2 may be filled in the groove or the hole.

When zirconia is sintered on the needle body 1, the zirconia grains 2 form a bonding portion 21 which is fitted into the groove or the hole, and when the bonding portion 21 is filled in the groove or the hole, the needle body 1 can store a larger amount of zirconia, further improving the bonding strength of the zirconia grains 2 and the needle body 1.

As an alternative embodiment, referring to fig. 2 to 4, the accommodating portion is a groove 11 recessed from the peripheral wall of the needle body 1 in the axial direction thereof.

Because zirconia is sintered at the position of the accommodating part on the needle body 1, when zirconia mass 2 is formed, the zirconia tightly wraps the part on the needle body 1 in the transverse direction, and in the vertical direction, the groove 11 forms a clamping force on the joint part 21 of the zirconia mass 2, so that the zirconia mass 2 is prevented from falling off due to the fact that the zirconia migrates to the needle point firstly due to gravity or the part attached to the needle body 1. And the structure of the groove 11 can better clamp the zirconia balls 2 to the needle body 1.

As an alternative embodiment, referring to fig. 2-4, each groove 11 surrounds the circumferential wall of the needle body 1, that is, the groove 11 is an annular groove 11, so that when zirconia is sintered, the zirconia inner ring can form a joint 21, the contact area of the zirconia grains 2 and the groove 11 is increased, and the effect of fastening the zirconia grains 2 by 360 ° is achieved.

As described with reference to fig. 2, the bonding sites 21 on the zirconia grains 2 are shaped to fit the shape of the grooves 11, and are formed in the grooves 11 when the zirconia is sintered.

As an alternative embodiment, referring to fig. 2 to 4, the number of the accommodating parts in the present embodiment is two or more, and all the accommodating parts are arranged at intervals along the length direction of the needle body 1.

The two or more receiving portions are engaged with the engaging portions 21 formed therein, and can fasten a plurality of portions of the zirconia grains 2, thereby increasing the number of zirconia grains and improving the engaging strength between the zirconia grains 2 and the needle body 1.

Referring to fig. 2 to 4, the cross section of the groove 11 is arc-shaped, the zirconia extending into the groove 11 fixes the whole zirconia lump 2 on the needle body 1 more stably, and as the temperature of the needle body 1 increases, the zirconia located in the groove 11, i.e., the bonding portion 21, is easy to flow out and migrate to the tip position of the needle body 1, and the electron emission work function is reduced under the action of the applied electric field, thereby improving the electron emission efficiency.

As an alternative embodiment, the zirconia grains 2 as the low work function material grains are ellipsoidal, which can store a sufficient amount of zirconia, and the ellipsoidal zirconia grains 2 can wrap the needle body 1 to improve the bonding strength; the extension length of the work function material ball is longer than the distribution length of all the combination parts 21 on the needle body 1, the upper end of the work function material ball completely wraps the combination part 21 positioned on the uppermost part of the needle body 1, and the lower end of the work function material ball completely wraps the combination part 21 positioned on the lowermost part of the needle body 1; the structure can fully utilize the grooves 11 on the needle body 1, and the zirconia lumps 2 can extend into each groove 11 during the sintering process as much as possible; meanwhile, the uppermost and lowermost grooves 11 are not exposed, as shown in fig. 2, and the zirconia grains 2 can be further prevented from falling off.

In an alternative embodiment, the low work function material cluster is a zirconia cluster 2, and the zirconia cluster 2 is disposed in the middle of the needle body 1 and above the needle point of the needle body 1, and does not affect the emission of electrons at the tip position of the needle body 1, so that the zirconia migrates to the needle point position of the needle body 1 under the action of high temperature, and the zirconia lost at the tip position of the needle body 1 can be continuously replenished.

Example 2

Referring to fig. 5, the present embodiment provides a thermal field emission electron source including the above-described emitter pin structure.

The thermal field emission electron source of the present invention has the above-described emission needle structure, and therefore, the service life thereof can be prolonged.

As an alternative embodiment, referring to fig. 5, the thermal field emission electron source further comprises an insulating mount 4, a suppressor electrode, a terminal 7, a heating prong 3, and a drawing-out electrode 6 having a diaphragm 61, wherein: the suppression pole is a Schottky suppression pole 5, and the suppression pole is covered outside the insulating base 4; all the binding posts 7 penetrate through the insulating base 4, one end of each binding post extends out of the insulating base 4, the other end of each binding post is fixed with the heating hair fork 3, the needle body 1 is fixed at the lower end of the heating hair fork 3 and extends out of the suppression pole, and the center of the needle body 1 is aligned with the center of the diaphragm 61.

The heating current is introduced from the terminal 7, the heating hair pin 3 is heated, and the needle body 1 is reheated. The electrons escape from the restriction of the tip of the needle body 1 under the action of the electric field of the suction electrode 6, and form continuous emission current.

Specifically, referring to fig. 5, the terminal 7 is used for electrifying and passing 2-3A current; the insulating seat 4 can be a ceramic seat, and is welded with a binding post 7 to support and insulate the transmitting needle; the Schottky suppressor electrode 5 applies a voltage of-300V to-1000V to suppress excessive large-angle stray electrons; the heating hair pin 3 is a tungsten hair pin, is welded on the binding post 7, generates heat after being electrified, and heats the tip of the needle body 1 to 1700-1800K; the needle body 1 is a single crystal tungsten needle which emits electrons under the action of an external electric field when heated to a high temperature; zirconia group 2 is sintered on the surface of the middle position of the needle body 1, and the zirconia group 2 can migrate and diffuse to the surface of the tip of the needle body 1 after being heated, so that the electron work function is reduced. The suction electrode 6 can apply 3000-8000V voltage, a strong electric field is formed at the position of the emission needle, electrons are attracted to emit, and only small-angle electrons are selected to pass through the diaphragm 61 for illumination.

Example 3

The present embodiment provides an electron microscope including the above thermal field emission electron source.

The electron microscope of the present invention has the above electron microscope, and therefore, the service life thereof can be prolonged.

The particular features, structures, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.