阅读说明：本技术 一种可快速响应的冷阴极平板脉冲x射线源及制备方法 (Cold cathode flat pulse X-ray source capable of fast responding and preparation method ) 是由 陈军 王成赟 邓少芝 许宁生 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种可快速响应的冷阴极平板脉冲X射线源,包括金属阳极基板和冷阴极电子源基板,所述金属阳极基板和冷阴极电子源基板之间保持真空间隙,所述冷阴极电子源基板中,包括绝缘衬底、底部条状阴极电极、在绝缘衬底上刻蚀的刻蚀通孔、顶部阴极电极、顶部环状栅极电极以及纳米冷阴极。同时公开了一种可快速响应的冷阴极平板脉冲X射线源的制备方法,本发明的冷阴极平板脉冲X射线源制备工艺简单,具备快速响应能力。(The invention discloses a cold cathode flat-plate pulse X-ray source capable of quickly responding, which comprises a metal anode substrate and a cold cathode electron source substrate, wherein a vacuum gap is kept between the metal anode substrate and the cold cathode electron source substrate, and the cold cathode electron source substrate comprises an insulating substrate, a bottom strip-shaped cathode electrode, an etched through hole etched on the insulating substrate, a top cathode electrode, a top annular grid electrode and a nano cold cathode. The invention also discloses a preparation method of the cold cathode flat pulse X-ray source with quick response.)

1. A cold cathode flat-plate pulse X-ray source capable of responding quickly, which is characterized by comprising a metal anode substrate and a cold cathode electron source substrate, wherein a vacuum gap is kept between the metal anode substrate and the cold cathode electron source substrate, and the cold cathode electron source substrate comprises:

a) an insulating substrate;

b) manufacturing a bottom strip-shaped cathode electrode below the insulating substrate;

c) a plurality of etching through holes which enable the bottom strip-shaped cathode electrode to be partially exposed are etched on the insulating substrate;

d) a top cathode electrode is manufactured on the insulating substrate and is connected with the bottom strip-shaped cathode electrode through the etching through hole;

e) a top annular gate electrode formed on the insulating substrate, surrounding the outside of the top cathode electrode, and not connected to the top cathode electrode;

f) and a nano cold cathode fabricated on the top cathode electrode.

2. The fast-response cold-cathode flat-plate pulse X-ray source of claim 1, wherein the metal anode substrate and the cold-cathode electron source substrate are fixed in an insulated manner by a spacer, and the distance between the cold-cathode electron source substrate and the metal anode substrate is 1 mm-20 mm.

3. The rapidly responsiveneable cold cathode flat-plate pulse X-ray source of claim 1, wherein said top cathode electrode is circular or annular in shape and has a diameter not greater than 1/3 of the width of said bottom strip-like cathode electrode, said top annular grid electrodes are coaxially distributed annularly around the perimeter of said top cathode electrode, the diameter of the inner ring of said top annular grid electrodes is not less than 1/3 of the width of said bottom strip-like cathode electrode, and the diameter of the outer ring of said top annular grid electrodes is not greater than 5/9 of the width of said bottom strip-like cathode electrode.

4. The fast-response cold-cathode flat-panel pulsed X-ray source of claim 1, wherein the metal anode substrate comprises a metal target, the metal target comprises a buffer layer film, a target layer film, and a protective layer film, the buffer layer film is disposed below the target layer film, and the protective layer film is disposed above the target layer film.

5. The fast-response cold-cathode flat-plate pulse X-ray source of claim 4, wherein the metal target is an Al-W-Al composite film or an Al-Mo-Al composite film.

6. The fast-response cold-cathode flat-plate pulse X-ray source of claim 1, wherein the width of said bottom strip-like cathode electrode is consistent with the width of said top ring-like gate electrode, and said width is 1 μm to 500 μm.

7. The fast-response cold-cathode flat-plate pulse X-ray source according to claim 1, wherein the top ring-shaped gate electrode is connected with a lead wire connected with an external power supply, the external power supply is used for applying a voltage to the top ring-shaped gate electrode, the waveform of the voltage is a direct current superimposed pulse waveform, the superimposed direct current amplitude is not more than 95% of the starting voltage of the cold-cathode electron source substrate, and the peak voltage range of the waveform is 10V-300V.

8. The fast-response cold-cathode flat-panel pulsed X-ray source of claim 1, wherein: the insulating substrate in the cold cathode electron source array is made of materials with excellent insulating property, and comprises glass, ceramics or other insulating materials, and the thickness of the insulating substrate is 1 mm-20 mm.

9. A method for preparing a fast-response cold-cathode flat-plate pulsed X-ray source according to any one of claims 1 to 8, comprising the steps of:

preparing a metal anode substrate:

depositing a metal target film on the insulating substrate in a localized manner, wherein the deposition sequence sequentially comprises a buffer layer film, a target layer film and a protective layer film;

preparing a cold cathode electron source substrate:

a) manufacturing a bottom strip-shaped cathode electrode below the insulating substrate;

b) etching a plurality of etching through holes on the insulating substrate, wherein the etching through holes are positioned above the bottom strip-shaped cathode electrode so as to expose the local part of the bottom strip-shaped cathode electrode;

c) manufacturing a top cathode electrode and a top annular grid electrode on the insulating substrate, wherein the top cathode electrode and the top annular grid electrode are connected with the bottom strip-shaped cathode electrode through the etching through hole;

d) manufacturing a cold cathode pre-growth film on the top cathode electrode;

e) reacting and growing on the cold cathode pre-growth film to obtain a nano cold cathode;

assembling a metal anode substrate and a cold cathode electron source substrate:

a) fixing the metal anode substrate part and the cold cathode electron source substrate part in an insulated way by using a separator;

b) a vacuum is maintained between the metal anode substrate and the cold cathode electron source substrate using a vacuum encapsulation process.

Technical Field

The invention relates to the technical field of vacuum micro-nano electronics, in particular to a cold cathode flat pulse X-ray source capable of quickly responding and a preparation method thereof.

Background

The cold cathode flat pulse X-ray source capable of fast responding has application prospect in X-ray imaging, communication and the like. The cold cathode flat-plate pulse X-ray source with large-area and quick response can be realized by utilizing the nanowire cold cathode electron source with the grid structure and the transmission anode target.

The existing gate structure nano cold cathode electron source is generally manufactured on a substrate, and the device structures are all positioned above the substrate. For example, in a patent (chinese patent ZL201610542509.8) entitled nanowire cold cathode electron source array with self-aligned focusing structure and a method for manufacturing the same, a top cathode electrode and a top annular gate electrode film are prepared by using a thin film deposition technique above a substrate and an insulating layer, a bottom cathode electrode strip and a bottom gate electrode strip are prepared by using a thin film deposition technique below the insulating layer above the substrate, and the connection between the upper electrode and the lower electrode is realized by etching through holes.

When the nano cold cathode electron source with the grid structure is applied to a cold cathode flat-plate pulse X-ray source with large area and quick response, the response time of the source when the source emits in large area is usually in the order of microseconds, the highest working frequency is low, and the requirement of high response cannot be met.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a cold cathode flat-plate pulse X-ray source with an optimized structure and capable of realizing quick response capability.

The invention adopts the following technical scheme to solve the prior technical problems:

a fast-response cold-cathode flat-plate pulsed X-ray source comprising a metal anode substrate and a cold-cathode electron source substrate, a vacuum gap being maintained between the metal anode substrate and the cold-cathode electron source substrate, the cold-cathode electron source substrate comprising:

a) an insulating substrate; b) manufacturing a bottom strip-shaped cathode electrode below the insulating substrate; c) a plurality of etching through holes which enable the bottom strip-shaped cathode electrode to be partially exposed are etched on the insulating substrate; d) a top cathode electrode is manufactured on the insulating substrate and is connected with the bottom strip-shaped cathode electrode through the etching through hole; e) a top annular gate electrode formed on the insulating substrate, surrounding the outside of the top cathode electrode, and not connected to the top cathode electrode; f) and a nano cold cathode fabricated on the top cathode electrode.

In the cold cathode electron source substrate, a bottom strip-shaped cathode electrode is prepared below an insulating substrate, a top cathode is connected with the bottom strip-shaped cathode electrode through an etching through hole penetrating through the insulating substrate, the insulating substrate is used as an insulating medium between a top annular grid electrode and the bottom strip-shaped cathode electrode, and the large thickness of the insulating substrate can greatly reduce the capacitance between the grid and the cathode, so that the device has the quick response capability far superior to that of a traditional structure.

Preferably, the metal anode substrate and the cold cathode electron source substrate are fixed in an insulated manner through an isolator, and the distance between the cold cathode electron source substrate and the metal anode substrate is 1 mm-20 mm.

Preferably, the top cathode electrode is circular or annular, the diameter of the top cathode electrode is not greater than 1/3 of the width of the bottom strip-shaped cathode electrode, the top annular grid electrodes are coaxially and annularly distributed in the peripheral area of the top cathode electrode, the inner ring diameter of the top annular grid electrode is not less than 1/3 of the width of the bottom strip-shaped cathode electrode, and the outer ring diameter of the top annular grid electrode is not greater than 5/9 of the width of the bottom strip-shaped cathode electrode.

The top annular grid electrode in the width size range has a good grid control effect, and meanwhile, the contact area of the top annular grid electrode and the bottom cathode in the intersecting region insulating layer is reduced, so that the capacitance between the grid electrode and the cathode can be reduced, and the response speed of the device is optimized.

Preferably, the metal anode substrate includes a metal target, the metal target includes a buffer layer film, a target layer film, and a protective layer film, the buffer layer film is disposed below the target layer film, and the protective layer film is disposed above the target layer film.

Preferably, the metal target is an Al-W-Al composite film or an Al-Mo-Al composite film.

W or Mo films are used to generate X-rays. An Al film is arranged under the W or Mo film and serves as a buffer layer film, so that the adhesion capability of the W or Mo film on the substrate is improved; an Al film is provided on the W or Mo film to serve as a protective film, which can prevent the W or Mo film from being oxidized.

Furthermore, the metal anode substrate mainly comprises an insulating substrate and a metal target, wherein a lead wire connected with an external power supply is connected to the metal target, the external power supply is used for applying voltage to the metal anode substrate, and the applied voltage range is 30 kV-180 kV.

Preferably, the widths of the bottom strip-shaped cathode electrode and the top annular gate electrode are kept consistent, and the widths are 1-500 μm.

Furthermore, the bottom strip-shaped cathode electrode, the top cathode electrode and the top annular gate electrode in the cold cathode electron source substrate are made of materials which have low resistivity and are compatible with micro-machining processes, and the materials comprise Cr, Al, Ti, Ag, Cu, ITO, IZO or AZO.

Furthermore, the nanometer cold cathode in the cold cathode electron source substrate is made of one or more of one-dimensional nanometer material ZnO, one-dimensional nanometer material CuO, one-dimensional nanometer material WOx, one-dimensional nanometer material CNTs, two-dimensional nanometer cold cathode film material graphene or two-dimensional nanometer cold cathode film material diamond films.

Furthermore, the material of the cold cathode pre-grown film can be one or more of tungsten, zinc, copper, iron, molybdenum, chromium or oxidizable metal materials, and the one-dimensional metal oxide nanometer cold cathode is obtained by means of thermal oxidation.

Preferably, the top annular gate electrode is connected with an outgoing line connected with an external power supply, the external power supply is used for applying voltage to the top annular gate electrode, the waveform of the voltage is a direct current superimposed pulse waveform, the superimposed direct current amplitude is not more than 95% of the starting voltage of the cold cathode electron source substrate, and the peak voltage range of the waveform is 10V-300V.

The superposed direct current waveform can enable the initial potential of the top annular grid electrode to fall near the starting voltage of the device through direct current bias in the waveform, so that the voltage amplification required by the grid voltage in the subsequent rising process to the pulse peak value is reduced, and the response speed of the device can be further improved.

Preferably, the insulating substrate in the cold cathode electron source array is made of a material with excellent insulating property, and comprises glass, ceramic or other insulating materials, and the thickness of the insulating substrate is 1 mm-20 mm.

The invention also discloses a method for preparing the cold cathode flat pulse X-ray source capable of quickly responding, which comprises the following steps:

preparing a metal anode substrate: depositing a metal target film on the insulating substrate in a localized manner, wherein the deposition sequence sequentially comprises a buffer layer film, a target layer film and a protective layer film;

preparing a cold cathode electron source substrate:

a) manufacturing a bottom strip-shaped cathode electrode below the insulating substrate; b) etching a plurality of etching through holes on the insulating substrate, wherein the etching through holes are positioned above the bottom strip-shaped cathode electrode so as to expose the local part of the bottom strip-shaped cathode electrode; c) manufacturing a top cathode electrode and a top annular grid electrode on the insulating substrate, wherein the top cathode electrode and the top annular grid electrode are connected with the bottom strip-shaped cathode electrode through the etching through hole; d) manufacturing a cold cathode pre-growth film on the top cathode electrode; e) reacting and growing on the cold cathode pre-growth film to obtain a nano cold cathode;

assembling a metal anode substrate and a cold cathode electron source substrate:

a) fixing the metal anode substrate part and the cold cathode electron source substrate part in an insulated way by using a separator; b) a vacuum is maintained between the metal anode substrate and the cold cathode electron source substrate using a vacuum encapsulation process.

Compared with the prior art, the invention has the beneficial effects that:

when the cold cathode flat pulse X-ray source works, high-voltage is applied to the anode substrate, and pulse driving voltage is applied between the corresponding top annular grid electrode and the bottom strip-shaped cathode electrode. The corresponding nanometer cold cathode can realize the emission and the regulation of electrons under the driving action of the grid voltage. By selectively applying voltages to the top ring-shaped gate electrode and the bottom strip-shaped cathode electrode, row-column addressed pulsed X-ray emission can be achieved.

In the cold cathode flat pulse X-ray source, the distance between the top annular grid electrode and the bottom strip cathode electrode is increased by placing the bottom strip cathode electrode below the substrate, so that the capacitance between the top annular grid electrode and the bottom strip cathode electrode is reduced, the quick response capability of the device is improved, the device has the quick response capability of ns-ps magnitude by adjusting the thickness of the used substrate and the size of the top annular grid electrode, and the highest working frequency can reach GHz magnitude.

By optimizing the pulse voltage waveform, the operating frequency of the device can be further improved by using the superposed direct current pulse waveform for driving.

The cold cathode flat-plate pulse X-ray source has simple preparation process, better addressable rapid pulse X-ray emission capability and important application prospect in the fields of X-ray imaging, deep space X-ray communication and the like as the flat-plate X-ray pulse source.

Drawings

FIG. 1 is a schematic diagram of a fast-response cold-cathode flat-plate pulse X-ray source according to the present invention;

FIG. 2 is a cross-sectional view of a left side view of a cold cathode electron source substrate in a fast-response cold cathode flat-plate pulsed X-ray source according to the present invention;

FIG. 3 is a front view of a cold cathode electron source substrate in a fast-response cold cathode flat-plate pulsed X-ray source according to the present invention;

FIG. 4 is a schematic diagram of a top view of a cold cathode electron source substrate in a fast-response cold cathode flat-plate pulsed X-ray source according to the present invention;

FIG. 5 is a flow chart of a process for fabricating a metal anode substrate in a fast-response cold-cathode flat-plate pulsed X-ray source according to the present invention;

FIG. 6 is a flow chart of a method for manufacturing a cold cathode electron source substrate in a fast-response cold cathode flat-plate pulsed X-ray source according to the present invention;

FIG. 7 is a resistance-capacitance equivalent circuit of a single lattice area in a cold cathode electron source substrate in a cold cathode flat pulse X-ray source with fast response according to the present invention;

FIG. 8 is a cross-sectional view showing the structure of a cold cathode electron source substrate of a conventional structure in which a cathode is located above a substrate;

FIG. 9 is a schematic diagram showing the comparison of waveforms of the superimposed DC pulse driving method and the normal pulse driving method according to the present invention;

description of the reference numerals

The device comprises a bottom strip-shaped cathode electrode 1, a cathode insulating substrate 2, an etched through hole 3, a top annular grid electrode 4, a top cathode electrode 5, a growth source film 6, a reacted growth source film 7, a nanowire cold cathode 8, an isolator 9, an oxidation protection layer film 10, a target layer film 11, a buffer layer film 12, an anode insulating substrate 13 and an insulating layer film 14.

Detailed Description

The present invention will be further described with reference to the following embodiments.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "top", "bottom", "inner", "outer", and the like, if any, are used in the orientations and positional relationships indicated in the drawings only for the convenience of describing the present invention and simplifying the description, but not for indicating or implying that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore the terms describing the positional relationships in the drawings are used for illustrative purposes only and are not to be construed as limiting the present patent.

Furthermore, if the terms "first," "second," and the like are used for descriptive purposes only, they are used for mainly distinguishing different devices, elements or components (the specific types and configurations may be the same or different), and they are not used for indicating or implying relative importance or quantity among the devices, elements or components, but are not to be construed as indicating or implying relative importance.