CN114655952A

CN114655952A - Electron multiplying material for microchannel plate, preparation method of electron multiplying material, microchannel plate prepared from electron multiplying material, and preparation method of microchannel plate

Info

Publication number: CN114655952A
Application number: CN202111515815.XA
Authority: CN
Inventors: 李兴辉; 李莉莉; 陈海军; 蔡军
Original assignee: Beijing Vacuum Electonics Research Institute
Current assignee: Beijing Vacuum Electonics Research Institute
Priority date: 2021-12-13
Filing date: 2021-12-13
Publication date: 2022-06-24
Anticipated expiration: 2041-12-13
Also published as: CN114655952B

Abstract

The invention discloses an electron multiplication material for a microchannel plate, preparation thereof, the microchannel plate prepared from the electron multiplication material and a preparation method of the microchannel plate. The method solves the problems that in the prior microchannel plate technology, the secondary electron emission coefficient of an oxide material for an electron multiplication layer is generally low, how to better combine an electron multiplication layer material (especially a diamond material) in a large-depth-width-ratio hole micropore of a microchannel plate, and the like.

Description

Electron multiplying material for microchannel plate, preparation thereof, microchannel plate prepared from electron multiplying material and preparation method of microchannel plate

Technical Field

The invention relates to the technical field of vacuum electronics. And more particularly, to an electron-multiplying material for a microchannel plate, preparation thereof, a microchannel plate prepared therefrom, and a method for preparing a microchannel plate.

Background

The electron multiplier tube is a vacuum tube capable of amplifying electric charges, primary electrons at the inlet of the vacuum tube impact the inner wall of the tube to beat the electrodes under the acceleration of an electric field to generate additional secondary emission electrons, and the additional electrons continuously impact the subsequent beat electrodes and are circulated and repeated for multiple times, so that a large number of electrons can be generated at the outlet of the vacuum tube to form an electron multiplication effect. An electron multiplier tube serving as a photoelectric detection device has been studied successfully in 1934, and is gradually applied to the fields of machinery, geology, metallurgy, astronomy, chemical engineering, electronics, medical imaging detection, cosmos research and the like.

In the conventional dynode electron multiplier, as shown in fig. 1, the electrodes are usually separated from each other, and the voltage of the latter dynode is higher than that of the former dynode by 100-200V to realize electron acceleration. The dynode type electron multiplier tube is simple to manufacture and easy to realize large current, but the dynode type electron multiplier tube has long transit time and large transit time dispersion (TTS). With the technological progress and the rapid development of high and new technologies, the requirements on the performance of scientific research and detection technology are continuously improved, and the micro-channel plate (MCP) type electron multiplier tube is in need of transportation.

The micro-channel plate type electron multiplier tube has the advantages of high gain, fast response, low power consumption, light weight and high resolution of two-dimensional space images, and the basic structure of the micro-channel plate type electron multiplier tube is shown in figures 2a-2 b. The microchannel plate body is formed by connecting a plurality of micron-sized channels which are parallel to each other in parallel, wherein each channel is a continuous electron multiplication unit. The electrodes in the micro-channel are not separated, but are connected into an integral electronic multiplication layer. The incident electrons continuously and repeatedly collide the electron multiplication layer, and the electron current is continuously enhanced.

The preparation method of the initial microchannel plate comprises the steps of longitudinally stretching and cutting close-packed glass tubes into blanks to form a tube bundle matrix based on a lead silicate glass tube stretching technology, and reducing lead in the glass matrix to form an electron multiplication layer on the inner wall of the tube. With the progress of the micromachining technology, a miniaturized and high-performance microchannel plate can be manufactured by using the advanced micro-electro-mechanical system technology. US 5086248 and US 5997713 respectively propose a process for preparing a microchannel plate based on a silicon material, wherein a Deep Reactive Ion Etching (DRIE) technology or an electrochemical and photoelectrochemical etching technology is adopted to directly prepare a dense and high-aspect ratio micropore array on a silicon wafer, and then an electron multiplication layer is prepared on the inner wall of the micropore array by a Chemical Vapor Deposition (CVD) or Atomic Layer Deposition (ALD) method. The micro-processing silicon-based micro-channel plate has the advantages that the preparation process is compatible with the micro-processing technology, the structures with different shapes and sizes are easy to realize, the process repeatability and the batch manufacturing capability are better, the development trend of multifunction, miniaturization, modularization, high reliability and integration of a high-precision detecting instrument is adapted, and the micro-processing silicon-based micro-channel plate becomes an important development direction of an electron multiplier tube.

The electron multiplier tube has the key technology that the electron multiplication effect is achieved through secondary electron emission, and the electron multiplication layer material is required to have a high secondary electron emission coefficient. The high secondary electron emission coefficient material mainly comprises an oxide material, a photocathode material, a negative electron affinity material, an alloy, glass and the like. The oxide material is widely applied due to simple process, easy preparation and strong physical and chemical stability. However, the secondary electron emission coefficient of the existing oxide materials is generally not high, and the maximum secondary electron emission coefficient delta_mGenerally only between 3-8.

Ordinary diamond is an insulating material, but its conductivity can be improved by doping, and diamond subjected to specific surface treatment is the only material with stable negative electron affinity in air. Due to the low atomic number, the escape depth of the secondary electrons is large, so that the diamond has high secondary electron emission capability. In addition, the diamond material has high thermal conductivity and good chemical stability, has great advantages when being used as an electron multiplication layer material, and is expected to greatly improve the performance of the existing electron multiplier tube.

The diamond material is used as a traditional electron multiplier tube electrode, and is relatively simple to prepare due to the macroscopic volume, but is difficult to use as an electron multiplication layer of a microchannel plate. The electron multiplication layer of the microchannel plate is formed by growing/coating a film in the tube after the electron channel is formed. No matter the glass tube type or the silicon-based micro-channel plate, the electron transmission channel is a thin tube with a large depth-width ratio of several microns to dozens of microns in diameter and hundreds of microns in length, even if a Chemical Vapor Deposition (CVD) method with the best film forming quality is adopted to manufacture a diamond film, because a series of process flows such as nucleation, film forming, treatment and the like are needed, uniform film layer coverage with a smooth surface on the inner wall of the electron transmission channel is difficult to realize, and the consistency among all micro-tubes is realized.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an electron-multiplying material for a microchannel plate, a preparation thereof, a microchannel plate prepared therefrom, and a method for preparing a microchannel plate. The method solves the problems that in the prior microchannel plate technology, the secondary electron emission coefficient of an oxide material for an electron multiplication layer is generally low, how to better combine an electron multiplication layer material (especially a diamond material) in a large-depth-width-ratio hole micropore of a microchannel plate, and the like.

In one aspect, the present invention provides an electron multiplying material for a microchannel plate, the electron multiplying material being a group iii element P-type doped diamond film.

Further, the group iii element is selected from boron.

In still another aspect, the present invention provides a method for preparing an electron-multiplying material for a microchannel plate, comprising the steps of:

uniformly coating diamond superfine nano-crystalline powder on a substrate, and nucleating to obtain a nucleation seed layer;

and depositing a group III element doped diamond film on the surface of the nucleation seed layer by adopting a vapor deposition method.

Further, the diamond ultra fine nanocrystalline powder has a grain size <10 nm.

Further, the nucleation density of the nucleation seed layer>10¹⁰/cm²。

In yet another aspect, the present invention provides a microchannel plate comprising an electron multiplication layer prepared from the electron multiplication material as described above or prepared by the method for preparing an electron multiplication material as described above.

Further, the thickness of the electron multiplication layer is 50-1000 nm.

In another aspect, the present invention provides a method for preparing a microchannel plate, comprising the steps of:

providing a substrate;

forming an array of posts at preselected locations on one surface of a substrate;

uniformly coating diamond superfine nanocrystalline powder on the surfaces of the substrate and the columnar array, and nucleating to obtain a nucleating seed layer; depositing a group III element doped diamond film on the surface of the nucleation seed layer by adopting a vapor deposition method to form an electron multiplication layer;

applying an insulating material on the electron multiplying layer until the column array is completely covered to form an insulating layer;

the surface of the insulating layer in the obtained structure is ground and polished until the top end of the columnar array is exposed;

removing the substrate, and grinding and polishing the surface combined with the substrate in the structure until the bottom end of the columnar array is exposed;

removing the columnar array to obtain an insulating layer structure with a through hole and an electronic multiplication layer coated on the through hole;

depositing conductive materials on the upper surface and the lower surface of the insulating layer structure except for the through holes respectively to form an input electrode and an output electrode;

carrying out surface treatment on the electron multiplication layer;

and obtaining the microchannel plate.

Further, the insulating material is an insulating material resistant to high electric field breakdown.

Further, the insulating material is applied by one selected from the group consisting of filling and curing, filling and sintering, chemical vapor deposition, and vacuum coating.

Further, the method for removing the substrate is selected from etching, grinding and polishing.

Further, the method of removing the columnar array is etching.

Further, the surface treatment method of the electron multiplication layer is hydrogenation treatment or cesium treatment.

The invention has the following beneficial effects:

in the preparation of the microchannel plate, the advantages of the diamond-doped thin film high secondary electron emission characteristic and the microstructure prepared by the micromachining technology are combined into a whole, so that the performance of the conventional electron multiplier tube can be preferentially improved. The method is simple and easy to implement, is favorable for obtaining the high-quality processed microchannel plate, and is suitable for urgent needs of scientific research and practicability.

The method for manufacturing the microchannel plate by using the prefabricated mould and then processing the microchannel plate firstly manufactures the diamond electron multiplication layer and then processes the electron transmission channel to prepare the microchannel plate, has simple process, can obtain the doped diamond film with high quality, high uniformity and smooth surface on the inner wall of the electron transmission channel by optimizing the process to the greatest extent, overcomes the limitation that the traditional microchannel plate only depends on glass and silicon material substrates, and can realize more excellent structure and device performance due to the diversity selection of the substrate materials and the processing process.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Fig. 1 shows a schematic diagram of a conventional dynode-type electron multiplier.

Wherein, 101-electron multiplier tube wall, 102-dozen and holding electrodes, 103-incident electron flow and 104-emergent electron flow.

FIG. 2a shows the overall structure of a conventional microchannel plate type electron multiplier and FIG. 2b shows a schematic diagram of a single microchannel of a conventional microchannel plate type electron multiplier.

Wherein, 201-microchannel wall, 202-electron multiplication layer, 203-input electrode, 204-output electrode, 205-incident electron flow and 206-emergent electron flow.

Figure 3 shows a photograph of silicon awl surface coated with diamond of different thickness.

Fig. 4a-4h show a flow chart of a process for preparing a microchannel plate with a doped diamond electron multiplication layer according to the invention.

Fig. 4i shows a doped diamond electron multiplication layer microchannel plate of the present invention.

Wherein, 301-silicon substrate, 302-column array, 303-nucleation seed layer, 401-doping diamond electron multiplication layer, 402-microchannel plate matrix, 403-electron transmission channel, 404-input electrode, 405-output electrode and 406-negative electron affinity surface.

FIG. 5 shows the variation of the secondary electron emission coefficient with incident energy of diamond films with different boron doping concentrations obtained by the methods of two embodiments of the invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below with reference to preferred embodiments and the accompanying drawings. Similar components in the figures are denoted by the same reference numerals. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

In the description of the present invention, "a plurality" means two or more unless otherwise specified; the terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing and simplifying the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

One embodiment of the present invention provides an electron multiplying material for a microchannel plate, the electron multiplying material being a group iii element P-type doped diamond film.

The electron multiplying material, when used in a microchannel plate, has a higher secondary electron emission coefficient than existing oxide materials.

Illustratively, the group iii element is selected from boron. At this time, the mass ratio of boron to diamond is preferably 3 to 16 ppm.

Yet another embodiment of the present invention provides a method for preparing an electron multiplying material for a microchannel plate. The method comprises the following steps:

uniformly coating diamond superfine nanocrystalline powder on a substrate, and nucleating to obtain a nucleating seed layer;

Illustratively, the diamond ultra-fine nanocrystalline powder has a grain size <10 nm.

Illustratively, the nucleation seed layer has a nucleation density>10¹⁰/cm²。

In the embodiment, no other requirements are required on the substrate, and the stable growth of the diamond film on the substrate can be realized.

Illustratively, the thickness of the electron multiplying material is preferably 50 to 1000 nm.

Another embodiment of the present invention provides a method for preparing a microchannel plate, as shown in fig. 4a to 4h, comprising the steps of:

1) a substrate 301 is provided.

The substrate 301 suitable for this embodiment may be a smooth and flat silicon wafer, preferably a surface-polished silicon wafer, and the flatness and roughness meet the requirements of micro-machining, particularly photolithography.

The dimensions of the substrate 301 are preferably standard microfabricated dimensions, such as 2 inches, 3 inches, 4 inches, 6 inches, or standard and non-standard substrates larger than 6 inches that are achievable with microfabrication.

A suitable thickness of the substrate 301 is preferably 400-2000 μm in view of the height of the pillars and the resistance to deformation of the holding base material in the subsequent manufacturing steps.

2) An array of posts 302 is formed at preselected locations on one surface of the substrate 301 as shown in fig. 4 a.

The size and shape of the pillar array 302 corresponds to the size and shape of the through-holes in the final microchannel plate to be fabricated (i.e., the effective useful area in the microchannel plate). In the column array 302, the column shape corresponds to the inner hole of the microchannel plate, the column gap corresponds to the channel wall thickness of the microchannel plate, and the column height corresponds to the thickness of the microchannel plate.

The shape of the columnar array 302 includes, but is not limited to, being a cylinder, a square column, a hexagonal prism, or the like. The shape of the correspondingly formed electron channel is correspondingly circular, square, honeycomb-shaped and the like.

In the pillar array 302, the pillar spacing is preferably about 4 microns, the diameter or length of the opposite sides of the individual pillars is preferably 6-40 microns, the pillar height is preferably 160-400 microns, and the aspect ratio of the pillars is preferably 10-40.

The material forming the pillar array 302 is preferably silicon, or other material suitable for micromachining to form high aspect ratio pillar structures and to withstand diamond CVD growth temperatures.

The method of forming the pillar array 302 may be a micromachining method. Specifically, it may be deep reactive ion etching (DRIE, direct machining on a silicon substrate), or other suitable micro-machining technology such as femtosecond laser.

The size range of the pattern of the pillar array 302 can be designed as required, or the pattern of the pillar array 302 can be densely distributed on the whole substrate, and the substrate is cut into a suitable size as required after the preparation.

3) Uniformly coating diamond superfine nano-crystalline powder on the surfaces of the substrate 301 and the columnar array 302 for nucleation to obtain a nucleation seed layer 303, as shown in fig. 4 b;

and depositing a group III element doped diamond film on the surface of the nucleation seed layer 303 by adopting a vapor deposition method to form an electron multiplication layer 401, as shown in fig. 4 c.

Illustratively, in diamond ultra fine nano-grain powders, the grain size is preferably <10nm, more preferably 3-5 nm.

Exemplary methods of coating diamond ultra-fine nanocrystalline powder include, but are not limited to, dielectric electrophoresis, ultrasonic coating, bias deposition, and the like.

Illustratively, the electron multiplication layer 401 has a thickness of 50-1000 nm.

In this embodiment, the reaction gas for vapor deposition is preferably B₂H₆And CH₄Conversely, the volume ratio of the two is preferably 2/10⁶-10/10⁶。

4) An insulating material is applied over the electron multiplication layer 401 to completely cover the pillar array 302, forming an insulating layer 402 (i.e., microchannel plate substrate), as shown in fig. 4 d.

Insulating materials that are robust and can withstand high electric field breakdown for ease of dense molding include, but are not limited to, resins, glass, quartz, ceramics, and the like.

The insulating material is preferably applied by one of filling sintering, chemical vapor deposition, and vacuum deposition.

The applied insulating material completely masks the pillar array 302 pattern structure such that the thickness of insulating layer 402 is greater than the height of pillar array 302. Thereby obtaining the flat and smooth upper plane of the microchannel plate.

5) The surface of the resulting structure, where insulating layer 402 is located, is lapped and polished until the tops of pillar arrays 302 are exposed, as shown in fig. 4 e.

It can be understood that, by grinding and polishing, part of the thickness of the insulating layer 402 and all of the electron multiplication layer 401 at the top end of the column array 302 are removed in sequence, so that the top end of the column array 302 is just exposed on the surface obtained by grinding and polishing.

The planarization, polishing method is preferably Chemical Mechanical Polishing (CMP), which first grinds the insulating layer quickly to thin it near the top of the pillar array, then slowly polishes away the material to expose the pillar array and simultaneously polish the entire top surface.

By this method, separation of the insulating layer 402 (microchannel plate substrate) and the electron multiplying material is achieved.

6) Removing the substrate 301 and grinding and polishing the surface of the structure combined with the substrate 301 until the bottom end of the columnar array 302 is exposed; and removing the pillar array 302, and obtaining an insulating layer structure having a through hole 403 (i.e. an electron transport channel) and an electron multiplication layer 401 coated on the through hole 403, as shown in fig. 4 f.

Methods of removing the substrate 301 include, but are not limited to, etching or grinding, polishing.

The surface of the structure bonded to the substrate 301 is ground, polished, or otherwise removed from the portion of the electron multiplication layer 401 bonded to the substrate 301.

Among them, the polishing method is preferably Chemical Mechanical Polishing (CMP).

The method for further removing the column array 302 may be etching, the etching method is wet chemical etching, and the same/different chemical etching solutions are selected according to the material identity/difference between the substrate 301 and the column array 302, and the etching solutions have good etching selectivity to other materials, that is, the insulating substrate of the microchannel plate and the electron multiplication layer 401 cannot be damaged in the etching removal process.

Compared with the existing silicon-based microchannel plate preparation method, the method has the advantages that the deep reaction ion etching silicon through hole is changed into the etching silicon column, so that the process difficulty is reduced, and the quality of an electron transmission channel is improved; compared with the existing microtube stretching method which only uses glass as a matrix, the micro-processing method only uses silicon as the matrix, and the substrate material of the microchannel plate has more selectivity.

According to the microchannel preparation process, the inner wall of the existing large-depth-to-width-ratio pipeline is coated with the diamond-doped electronic multiplication layer, and the outer surface of the cylindrical structure is coated, so that the process difficulty is greatly reduced, and better uniformity, consistency and surface smoothness are realized. Research shows that even for the micro-nano structure, uniform and smooth conformal deposition can be realized. FIG. 3 shows the result of coating the surface of a silicon conical tip with a diamond film at a height of 8 microns and a tip curvature radius of 10nm, and uniform coating can be realized when the film thickness is 0.1-2.4 microns. And the electron multiplication layer is obtained by the preparation method, the actual secondary electron emission surface is the inner surface attached to the silicon column mold, and the surface is easier to realize high smoothness compared with the chemical vapor deposition outer surface, so that the electron multiplication capacity is improved.

7) Conductive materials are deposited on the upper and lower surfaces of the insulating layer structure except for the via 403 to form an input electrode 404 and an output electrode 405, respectively, as shown in fig. 4 g.

The method of depositing the conductive material is preferably a thin film deposition method. An exemplary method of thin film deposition is a vacuum evaporation coating method with good directionality. In order to ensure that the deposition layer is only positioned on the upper end surface and the lower end surface of the microchannel plate and does not enter the electron channel, the evaporation source is far away from the end surface of the microchannel plate and keeps a small sweep angle with the end surface of the microchannel plate for oblique evaporation. Meanwhile, in order to ensure uniformity, the microchannel plate rotates around the normal of the end face in the evaporation process.

In order to combine the bonding firmness and the good conductivity, the conductive material comprises but is not limited to one selected from the group consisting of chromium nickel, titanium nickel, chromium gold and titanium gold.

The thickness of the input electrode 404 and the output electrode 405 are each independently selected from 100-300 nm.

8) The electron multiplication layer 401 is surface treated as shown in fig. 4 h.

By the surface treatment, a negative electron affinity surface 406 is formed on the surface of the electron multiplication layer 401.

The electron multiplication layer is surface-treated by, for example, a hydrogenation treatment or a cesium treatment.

Yet another embodiment of the present invention provides a microchannel plate, as shown in fig. 4i, comprising an electron-multiplying layer 401 prepared from an electron-multiplying material as described above or prepared by a method for preparing an electron-multiplying material as described above.

Further, the thickness of the electron multiplication layer 401 is 50-1000 nm.

Example 1

A microchannel plate, as shown in FIG. 4i, comprises a doped diamond electron multiplication layer 401, a microchannel plate substrate 402, an electron transport channel 403, an input electrode 404 and an output electrode 405, wherein the surface of the doped diamond electron multiplication layer 401 has a negative electron affinity surface 406.

The preparation method comprises the following steps:

1) a <100> crystal orientation polished silicon wafer is selected as a substrate 301, the diameter of the silicon wafer is 4 inches, the thickness of the silicon wafer is 500 micrometers, and the surface flatness and warping degree of the silicon wafer are superior to 10 micrometers; thermally oxidizing 0.5 micron silicon dioxide and magnetron sputtering 1 micron metal aluminum on the surface of the silicon wafer, and etching the silicon dioxide and the metal aluminum by standard photoetching to form a masking layer; etching a silicon substrate to form a column array 302 by using a deep silicon etching technology of Bosch patent of STS company; the etching power is 600W/15W, the etching rate is 1.5 mu m/min, the etching time is 200min, and the etching depth is 300 microns; according to the design pattern, a densely-distributed hexagonal column array 302 is obtained on a silicon wafer, the distance between the opposite sides of the columns is 15 micrometers, the column gap is 4 micrometers, the column height is 300 micrometers, and the column aspect ratio is 20.

2) Forming a structure by a substrate 301 and a columnar array 302, placing the structure in an ethanol suspension of diamond superfine nano-crystalline powder with the grain size of 3-5nm, ultrasonically vibrating for 30min at 100W, immersing in acetone for cleaning for 5 min, forming a nucleation seed layer 303 of diamond on the surfaces of the substrate 301 and the columnar array 302 structure, and forming nucleation density>10¹⁰/cm²。

3) The substrate 301, the columnar array 302 and the nucleation seed layer 303 form a structure, the whole is placed in chemical vapor deposition equipment, and a layer of boron-doped diamond film is deposited on the surface of the nucleation seed layer 303 to serve as an electron multiplication layer 401. The carbon source of the diamond is CH during deposition₄The boron source is B₂H₆，B₂H₆And CH₄Feed volume ratio of 10/10⁶The total gas flow is 300sccm, the discharge reaction pressure is 80Torr, the microwave power is 1400W, and the substrate heating temperature is 800 ℃. The deposition time is 60min, and the thickness of the obtained film layer is about 1 micron.

4) The microchannel plate substrate 402 is formed by evaporation of 95% alumina ceramic into the substrate and columnar array gap using electron beam evaporation. The evaporation power is 2kW, the evaporation rate is 2 mu m/min, the evaporation time is 160min, and the alumina ceramic microchannel plate substrate 402 with the thickness of about 320 mu m and completely covering the columnar array 302 with the height of 300 mu m and the surface nucleation seed layer 303 is obtained.

5) The alumina ceramic microchannel plate substrate 402 is ground and polished by a chemical mechanical polishing method with diamond powder as an abrasive. The method comprises the following steps of firstly, rapidly grinding by adopting an abrasive material with the granularity of 10 microns and at the rotating speed of 200RPM (revolution per minute), and reducing the thickness of an alumina ceramic matrix to 300 microns; and then polishing slowly at a rotating speed of 60RPM by adopting a 1-micron abrasive until the alumina ceramic matrix 402 and the doped diamond electron multiplication layer 401 at the top of the silicon-based columnar array 302 are completely ground to expose silicon materials.

6) And (3) grinding and polishing the substrate 301 by adopting a chemical mechanical polishing method, such as the process in the step 5) until the substrate 301 and the diamond electron multiplication layer 401 at the bottom of the alumina ceramic matrix 402 are completely removed, and exposing the alumina ceramic material. Then, corroding the silicon material by using a potassium hydroxide solution to completely remove the column array 302; the concentration of the potassium hydroxide solution is 30 percent, the corrosion temperature is 80 ℃, and the corrosion rate of the silicon material is about 1 mu m/min; for the 300 micron column array 302, over-etching (double-sided etching) is carried out for 200 minutes to ensure that all silicon materials are removed (the column array has difficulty in coating and removing the narrow channel), and an electron transmission channel 403 is formed at the original position of the column array 302 due to material removal. This results in a microchannel plate structure consisting of the doped diamond electron multiplication layer 401, the microchannel plate substrate 402, and the electron transport channel 403. The honeycomb-shaped electronic transmission channel 403 is in a shape corresponding to the columnar array, the distance between the opposite sides of the hexagonal through holes is 15 micrometers, the wall thickness is 4 micrometers, and the depth is 300 micrometers.

7) The input electrode 404 is made by depositing a conductive material on the upper end surface of the microchannel plate by an electron beam evaporation deposition method. During evaporation, the target source is far away from the microchannel plate and forms an incident grazing angle of 15 degrees with the end face, and meanwhile, the microchannel plate rotates along the normal direction of the end face to ensure that evaporant is uniformly deposited on the surface and does not enter the electron transmission channel 403. The input electrode 404 is a composite film of 20nm titanium and 100nm nickel. The same method prepares the output electrode 405 on the lower end face of the microchannel plate.

8) And (3) carrying out surface treatment on the manufactured diamond film to obtain the negative electron affinity performance, wherein the treatment method is to use hydrogen plasma. Putting the microchannel plate with the integral structure in the chemical vapor deposition equipment again, and introducing H₂The gas flow is 300sccm, the discharge reaction pressure is 80Torr, the microwave power is 1000W, the substrate heating temperature is 800 ℃, the treatment is carried out for 10min, and a negative electron affinity surface 406 is formed on the surface of the diamond electron multiplication layer 401 doped on the inner wall of the electron transmission channel 403.

Example 2

The preparation method is the same as that of example 1, except that:

b in step 3)₂H₆And CH₄Reaction gas feed volume ratio of 10/10⁶Adjusted to 2/10⁶So as to reduce the boron doping concentration of the diamond electron multiplication layer 401, and the rest conditions are kept unchanged.

The boron-doped diamond film obtained by the chemical vapor deposition method in the embodiment has the surface appearance similar to that of an undoped diamond film, but the diamond grains are finer, and the film shows a lower resistance value measured by a multimeter, which shows that the film is converted from a non-conductive body to a conductive body. Measurements on boron-doped diamond films show that the secondary electron emission coefficient increases substantially with increasing electron incident energy, reaches a maximum at 1keV and then decreases; within a certain range, the secondary electron emission coefficient is improved along with the increase of the boron doping concentration in the film.

The boron-doped diamond film was prepared by chemical vapor deposition in two examples, high doping B in example 1₂H₆/CH₄＝10/10⁶Example 2 Low doping case B₂H₆/CH₄＝2/10⁶The results of the secondary electron emission coefficient test are shown in FIG. 5. The results show that even in the case of the lower boron doping of example 2, the secondary electron emission coefficient delta is 10.9 at an electron incidence energy of 1keV, and that in the case of the higher doping of example 1, the delta value is as high as 18.3, both of which are much higher than the existing oxide electron multiplication layer materials. Therefore, when the boron-doped diamond film is used as the electron multiplication layer material in the microchannel plate, and by the preparation method of the microchannel plate in the embodiment of the present invention, a uniform boron-doped diamond film with a smooth surface is realized on the inner wall of the electron transmission channel, so that the microchannel plate also has the above effects, which is not described herein again.

And (4) conclusion: the invention surprisingly discovers that the preparation method of the microchannel plate by using the prefabricated mould post-processing method not only has simple process and theoretically avoids the limitation of materials and the mutual influence between the preparation processes caused by the difference of material characteristics, but also can conveniently realize the realization of smooth and uniform diamond material electron multiplication layers on the inner wall of the electron transmission channel and obtain high-quality results. The method provided by the invention is simple and easy to implement, has low cost and wide range of selectable materials, and is suitable for urgent needs of scientific research and practicability.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications that are included in the technical solutions of the present invention are within the scope of the present invention.

Claims

1. An electron multiplying material for a microchannel plate, wherein the electron multiplying material is a group iii element P-type doped diamond film.

2. The electron multiplying material of claim 1, wherein the group iii element is selected from boron.

3. A preparation method of an electron multiplication material for a microchannel plate is characterized by comprising the following steps:

and depositing to form a group III element doped diamond film on the surface of the nucleation seed layer by adopting a vapor deposition method.

4. A method of manufacturing according to claim 3, wherein the diamond ultra fine nano-grain powder has a grain size <10 nm;

preferably, the nucleation density of the nucleation seed layer>10¹⁰/cm²。

5. A microchannel plate comprising an electron multiplying layer prepared from the electron multiplying material according to claim 1 or 2.

6. The microchannel plate of claim 5, wherein the electron multiplication layer has a thickness of 50 nm to 1000 nm.

7. A preparation method of a microchannel plate is characterized by comprising the following steps:

providing a substrate;

uniformly coating diamond superfine nano-crystalline powder on the surfaces of the substrate and the columnar array, and nucleating to obtain a nucleation seed layer; depositing a group III element doped diamond film on the surface of the nucleation seed layer by adopting a vapor deposition method to form an electron multiplication layer;

applying an insulating material on the electron multiplication layer until the column array is completely covered to form an insulating layer;

removing the columnar array to obtain an insulating layer structure with a through hole and an electron multiplication layer coated on the through hole;

carrying out surface treatment on the electron multiplication layer;

and obtaining the microchannel plate.

8. The production method according to claim 7, wherein the insulating material is an insulating material resistant to high electric field breakdown;

preferably, the insulating material is applied in a manner selected from one of pack curing, pack sintering, chemical vapor deposition, and vacuum coating.

9. The method of claim 7, wherein the substrate is removed by a method selected from etching or grinding, polishing;

preferably, the method of removing the columnar array is etching.

10. The production method according to claim 7, wherein the surface treatment of the electron-multiplied layer is a hydrogenation treatment or a cesium treatment.