CN110854007A - Flat-panel X-ray source based on X-ray micro-pixel unit and preparation method thereof - Google Patents

Abstract

The present application discloses a flat-panel X-ray source based on an X-ray micro-pixel unit, comprising a cathode substrate, an anode substrate and a high-voltage insulating spacer; the cathode substrate and the anode substrate are arranged relatively parallel, and the high-voltage insulating spacer is arranged The invention also discloses a preparation method of a flat-panel X-ray source based on an X-ray micro-pixel unit, including manufacturing a cathode substrate, manufacturing an anode substrate and assembling, The insulating layer covering method can effectively reduce the fringe electric field of the bottom cathode electrode strip and reduce the possibility of discharge phenomenon, thereby further improving the anode voltage. At the same time, it can improve the working stability of the device and prolong the service life of the device. The flat metal targets are arranged in one-to-one correspondence with the top cathode electrode and the growth source film to form an array of X-ray micro-pixel units, so that the flat-panel X-ray source has spatial resolution.

Description

A flat-panel X-ray source based on X-ray micro-pixel unit and preparation method thereof

technical field

The present invention relates, more particularly, to a flat-panel X-ray source based on an X-ray micro-pixel unit and a preparation method thereof.

Background technique

Chinese patent CN201811178220.8 "An addressable nano-cold cathode flat X-ray source and its preparation method" discloses a flat X-ray source that uses cathode electrode strips and anode electrode strips to directly intersect in space, although it can be It realizes the addressing function, but due to its exposed cathode electrode, it will easily lead to the problem of electrode edge discharge in high-voltage operation, which will damage the device and cause insufficient anode voltage to achieve transmission imaging of high-density tissue and metal materials. At the same time, the use of the entire anode electrode strip will cause the flat-panel X-ray source to have no spatial resolution, and it cannot form a true X-ray micro-pixel unit array. Correspondingly, this means that, in addition to the disk area corresponding to the growth source film, other linear areas will also generate X-rays. In order to maintain conductivity, the width of the linear area of the anode electrode strip is basically unchanged. The larger the number, the smaller the area of the disc area in the anode metal target electrode strip, which tends to be more linear, making the flat-panel X-ray source without spatial resolution, making it suitable for medical imaging, industrial flaw detection and safety inspection, etc. The application in the field is limited to a certain extent.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a flat-panel X-ray source based on an X-ray micro-pixel unit, the flat-panel X-ray source can improve anode voltage and have spatial resolution.

The present invention is achieved through the following technical solutions:

A flat-panel X-ray source based on an X-ray micro-pixel unit, comprising a cathode substrate, an anode substrate and a high-voltage insulating spacer; the cathode substrate and the anode substrate are relatively parallel to each other, and the high-voltage insulating spacer is disposed on the cathode between the substrate and the anode substrate to separate the two, the cathode substrate includes a cathode substrate, two or more bottom cathode electrode strips arranged in parallel on the cathode substrate, and an insulating layer covering the bottom cathode electrode strips , etched through holes made in the insulating layer to partially expose the bottom cathode electrode strip, a top cathode electrode made on the insulating layer, a growth source film arranged on the top cathode electrode, the A nanowire cold cathode is grown on the growth source film, the top cathode electrode is connected to the bottom cathode electrode strip through the etched through hole, the anode substrate includes an anode substrate, and two or more lines are arranged in parallel on the anode substrate. Anode electrode strips and circular metal targets made on the anode electrode strips, each of the anode electrode strips and each of the bottom cathode electrode strips are vertically intersected in space and have an intersection, and the top The cathode electrode and the growth source film are located at the intersection, the top cathode electrode is arranged on the bottom cathode electrode strip in the form of an array, the circular metal target is located at the intersection, and the circular metal target is located at the intersection. The metal targets are arranged on the anode electrode strips in an array form, and the growth source film and the circular metal target constitute an X-ray micro-pixel unit.

Disposing the growth source film on the top cathode electrode and burying the bottom cathode electrode strip under the insulating layer can prevent the bottom cathode electrode strip from being directly exposed to the outside, thereby eliminating the discharge problem that occurs at the edge of the electrode strip under high voltage. In particular, the growth source film can completely cover the top cathode electrode, and the discharge position of the top cathode electrode mostly occurs at the edge of the top cathode electrode. Covering the top cathode electrode with the growth source film is equivalent to protecting the edge of the top cathode electrode. .

A circular metal target is arranged on the anode electrode strip, and the growth source film and the circular metal target can correspond one-to-one to form an X-ray micro-pixel unit, so that there will be no X-rays in other linear areas outside the disk area. The result is that as the number of arrays increases, the string shape can still be maintained, allowing the flat panel X-ray source to have spatial resolution.

The cathode substrate and the anode substrate are arranged opposite and parallel to each other, so that each of the anode electrode strips and each of the bottom cathode electrode strips vertically intersect in space and have an intersection point, and a plurality of the anode electrode strips and a plurality of the bottom cathode electrode strips The electrode strips intersect vertically so that the intersections are arranged in an array. The growth source film disposed on the top cathode electrode and the circular metal target are located at the intersection, and together form an X-ray micro-pixel unit, thereby realizing the addressing function based on the X-ray micro-pixel unit.

In operation, the anode electrode strip is connected to an external high voltage power supply, the bottom cathode electrode strip is grounded, and the voltage of the external high voltage power supply is greater than 6KV. When one or more of the anode electrode strips are connected to an external high voltage power supply, and one or more of the bottom cathode electrode strips are grounded, the intersection of the anode electrode strips connected to the external high voltage power supply and the grounded bottom cathode electrode strips X-rays will be generated at the point; further, the voltage range of the external high voltage power supply is 10kV to 150kV.

The remaining anode electrode strips and the bottom cathode electrode strips can be chosen not to be connected to the external high-voltage power supply and ground, that is, to be suspended. The intersection of anode electrode strip and cathode electrode strip connected to the circuit will generate X-ray emission, and the unit not connected to the circuit will not generate X-ray. Therefore, the number of anode electrode strips and cathode electrode strips connected to the circuit directly affects The number of working micro-units in the flat-panel X-ray source.

Further, the nanowire cold cathodes are zinc oxide nanowires, copper oxide nanowires, tungsten oxide nanowires, molybdenum oxide nanowires, iron oxide nanowires, titanium oxide nanowires or tin oxide nanowires.

Further, the growth source film is prepared from any one of zinc, copper, tungsten, molybdenum, iron, titanium and tin, and its thickness ranges from 0.3 μm to 5 μm.

Further, the shape of the growth source film is a symmetrical figure, and the diameter or side length of the growth source film is 5 μm-500 μm; the distance between the adjacent growth source films is 0.1-10 times the diameter or side length. . The shape of the growth source film is circular, annular or polygonal.

Further, the cathode substrate is composed of a large-area silicon wafer, glass, quartz glass or ceramic substrate; the bottom cathode electrode strip and the top cathode electrode are Cr, Al, Ti, Cu, ITO, IZO, The bottom cathode electrode strip and the top cathode electrode have a thickness ranging from 0.1 μm to 2 μm; the shape of the top cathode electrode is a circle or a polygon. .

Further, the insulating layer is made of any one of silicon oxide, silicon nitride or aluminum oxide or a combination thereof, and the thickness of the insulating layer is 1 μm-5 μm. The number of the insulating layers is one or more layers, and the insulating thin films can be prepared by common thin film preparation methods, such as electron beam evaporation, magnetron sputtering, and chemical vapor deposition.

The invention uses the insulating layer to cover the bottom cathode electrode strip, which can avoid the direct intersection of the bottom cathode electrode strip and the edge of the anode electrode strip in space, thereby effectively reducing the fringe electric field of the bottom cathode electrode strip, reducing the possibility of discharge phenomenon, and realizing the anode voltage While further improving, the working stability of the device is improved, the service life of the device is prolonged, and its practical application in the fields of medical imaging, industrial flaw detection and safety inspection is broadened.

Further, the anode substrate is composed of a large-area silicon wafer, glass, quartz glass or ceramic substrate; the anode electrode strip is prepared by one or more combinations of ITO, IZO, AZO, FTO, and LTFO. The thickness of the anode electrode strip is in the range of 0.1 μm-2 μm; the circular metal target is made of one or two of tungsten, molybdenum, rhodium, silver, copper, gold, chromium, aluminum, niobium, tantalum, and rhenium. The thickness of the circular metal target is 0.2 μm-1000 μm. The anode electrode strip only serves as a conductive connection, and the part that generates the X-rays is a circular metal target.

Further, the anode electrode strips are prepared by metal shadow mask and vacuum coating technology, or by photolithography, etching process, vacuum coating and lift-off technology, or directly by screen printing or inkjet printing. The vacuum coating technology includes magnetron sputtering, electron beam evaporation, and vacuum thermal evaporation, and the photolithography technology can use ultraviolet photolithography.

Further, the high voltage insulating spacer is made of glass, quartz, ceramics or insulating plastics; the height of the high voltage insulating spacer is 0.5mm-100mm.

Another object of the present invention is to provide a method for preparing a flat-panel X-ray source based on an X-ray micro-pixel unit, comprising the following steps:

S1. Make cathode substrate and anode substrate:

The steps of cathode substrate are:

making bottom cathode electrode strips on the cathode substrate; covering the bottom cathode electrode strips with an insulating layer; etching the insulating layer to make etched through holes on the bottom cathode electrode strips; forming a top cathode electrode connected to the bottom cathode electrode strip; depositing a growth source film; thermally oxidizing the growth source film to grow a nanowire cold cathode to obtain a cathode substrate;

The preparation steps of the anode substrate are:

An anode electrode strip is made on an anode substrate; a circular metal target array is made on the anode electrode strip to obtain an anode substrate;

S2. Assembling, the cathode substrate and the anode substrate prepared by the above steps are relatively parallel arranged, the nanowire cold cathode on the cathode substrate faces the circular metal target on the anode substrate, the growth source film and the circular metal target are One-to-one correspondence; high-voltage insulating separators are used to isolate and fix the cathode substrate and the anode substrate, and ensure that each anode electrode strip and each bottom cathode electrode strip are spatially perpendicular to each other and have a cross point, the said The top cathode electrode and the growth source film and the circular metal target are all located at the intersection, and the circular metal target and the growth source film constitute an X-ray micro-pixel unit.

The bottom cathode electrode strip and the top cathode electrode are prepared by metal shadow mask and vacuum coating technology, or by photolithography, etching process, vacuum coating and lift-off technology, or directly by screen printing or inkjet printing. The vacuum coating technology includes magnetron sputtering, electron beam evaporation, and vacuum thermal evaporation, and the photolithography technology can use ultraviolet photolithography. The etched through holes are prepared by an etching process, and common etching methods such as wet etching and reactive ion etching can be used. The growth source film can be deposited on the top cathode electrode by magnetron sputtering, vacuum thermal evaporation or electron beam evaporation.

Further, the thermal oxidation method includes a heating process and a heat preservation process, and the heating rate of the heating process is 1°C/min-30°C/min; After the heat preservation, it was naturally cooled to room temperature.

Further, one or two or more combined gases of Ar, H ₂ , N ₂ , and O ₂ are introduced into the temperature-raising process and the heat-retaining process. The growth of zinc oxide nanowires, copper oxide nanowires, tungsten oxide nanowires, molybdenum oxide nanowires, iron oxide nanowires, titanium oxide nanowires or tin oxide nanowires is related to the oxygen concentration. Control the growth of nanowires.

Compared with the prior art, the beneficial effects of the present invention are:

The nano-cold cathode flat X-ray source of the present invention is fabricated by an insulating layer covering method, and the bottom cathode electrode strip is covered by the insulating layer, thereby avoiding the direct intersection of the bottom cathode electrode strip and the anode electrode strip in space, and effectively reducing the bottom cathode electrode strip. The fringe electric field of the electrode strip reduces the possibility of the discharge phenomenon, thereby further improving the anode voltage, and at the same time, it can improve the working stability of the device and prolong the service life of the device.

A circular metal target is set on the anode electrode strip, and the growth source film and the circular metal target can achieve a true one-to-one correspondence to form an X-ray micro-pixel unit, so that there is no X-ray in other linear areas outside the disk area. The ray generation, when the number of arrays increases, can still be distributed independently of each other, so that the flat panel X-ray source has spatial resolution, which can be used in medical imaging, industrial flaw detection and security inspection and other fields, and is conducive to the clarity of the image And it is conducive to the analysis and reconstruction of the image in the later stage.

The top cathode electrodes are arranged on the bottom cathode electrode strips in the form of an array, and the circular metal targets are arranged on the anode electrode strips in an array form. The X-rays are emitted point, line by line and partition to realize the addressing function.

Description of drawings

1 is a structural cross-sectional view of a flat-panel X-ray source based on an X-ray micro-pixel unit of the present invention;

Figure 2(a)-(g1)/(g2) is a process step diagram for preparing a cathode substrate of a flat X-ray source based on an X-ray micro-pixel unit;

3 is a schematic structural diagram of a cathode substrate of a flat X-ray source based on an X-ray micro-pixel unit according to the present invention;

Figures 4(a)-(c) are diagrams showing the manufacturing process steps of a flat X-ray source anode substrate based on an X-ray micro-pixel unit;

5 is a schematic structural diagram of an anode substrate of a flat-panel X-ray source based on an X-ray micro-pixel unit according to the present invention;

6 is a schematic diagram of the overall structure of a flat-panel X-ray source based on an X-ray micro-pixel unit of the present invention;

7 is another structural cross-sectional view of a flat-panel X-ray source based on an X-ray micro-pixel unit of the present invention;

8 is a schematic diagram of the overall structure of a 1-nanometer cold cathode flat X-ray source in Comparative Example;

Description of reference numerals

Cathode substrate 10, anode substrate 20, high voltage insulating separator 30, cathode substrate 11, bottom cathode electrode strips 12, insulating layer 13, etched vias 14, top cathode electrode 15, growth source film 16, nanowire cold cathode 17 , anode substrate 21, anode electrode strip 22, circular metal target 23, comparative example cathode substrate 110, comparative example anode substrate 120, comparative example high voltage insulating separator 130, comparative example cathode substrate 111, comparative example cathode electrode strip 112 , Comparative example growth source film 113 , comparative example nanowire cold cathode 114 , comparative example anode substrate 121 , comparative example anode metal target electrode strip 122 .

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1

As shown in FIG. 1 , it is a schematic structural diagram of a flat-panel X-ray source based on an X-ray micro-pixel unit of the present invention.

The nano-cold cathode flat X-ray source of the present invention includes a cathode substrate 10 , an anode substrate 20 , and a high-voltage insulating spacer 30 . The cathode substrate 10 and the anode substrate 20 are arranged in parallel and opposite to each other, and the high-voltage insulating spacer 30 is arranged between the cathode substrate 10 and the anode substrate 20 to isolate and fix the cathode substrate 10 and the anode substrate 20 . There is a certain distance between the cathode substrate 10 and the anode substrate 20 .

The cathode substrate 10 includes a cathode substrate 11, two or more bottom cathode electrode strips 12 arranged in parallel on the cathode substrate 11, an insulating layer 13, an etched through hole 14, a top cathode electrode 15, a growth source film 16, and a nanometer Line cold cathode 17. The bottom cathode electrode strips 12 are arranged parallel to each other on the side of the cathode substrate 11 facing the anode substrate 20 . The insulating layer 13 is disposed on the bottom cathode electrode strip 12 . The etched through hole 14 is disposed in the insulating layer 13 and partially exposes the bottom cathode electrode 12 . The top cathode electrode 15 is disposed on the etched through hole 14 . The growth source film 16 is grown on the top cathode electrode 15 . A nanowire cold cathode 17 is grown on the growth source film 16 in a direction perpendicular to the growth source film 16 .

The anode substrate 20 includes an anode substrate 21, two or more anode electrode strips 22 arranged in parallel on the anode substrate 21, and a circular metal target 23 fabricated on the anode electrode strips.

The above-mentioned manufacturing method of a flat-panel X-ray source based on an X-ray micro-pixel unit includes the manufacture of cathode substrate, the manufacture of anode substrate, and the combination of the flat panel X-ray source. Specific steps are as follows:

S1. Fabrication of the cathode substrate 10 and the anode substrate 20 .

The cathode substrate 10 was produced. As shown in Figure 2(a)-(g1)/(g2) and Figure 3, the specific production steps are as follows:

(1) Clean and dry the cathode substrate 11; the cathode substrate 11 is large-area glass.

(2) A cathode electrode strip 12 is fabricated on the cathode substrate 11; the bottom cathode electrode strip 12 is ITO. The bottom cathode electrode strip 12 has a thickness of 1 μm and a rectangular shape. The bottom cathode electrode strip 12 is prepared by vacuum coating technology, photolithography and etching process. The vacuum coating technology is magnetron sputtering, the photolithography technology is ultraviolet photolithography, and the etching process is a wet etching process.

(3) An insulating layer 13 is deposited on the bottom cathode electrode strips 12 . The insulating film used as the insulating layer 13 is composed of a silicon oxide insulating film. The insulating layer 13 is prepared by general chemical vapor deposition, and the thickness of the insulating layer is 3 μm.

(4) Locally etch the insulating layer on the insulating layer 13 to obtain etched through holes 14 for connecting the top cathode electrode and the corresponding bottom cathode electrode strip. The etched through holes 14 may be fabricated by reactive ion etching.

(5) The top cathode electrode 15 is prepared over the etched through hole 13 . The top cathode electrode 15 is connected to the corresponding bottom cathode electrode strip 12 through etched vias 14 in the insulating layer 13 . The top cathode electrode 15 is ITO, the thickness of the top cathode electrode 15 is 1 μm, and its shape is circular. The top cathode electrode 15 is prepared by vacuum coating technology, photolithography and etching process. The vacuum coating technology is magnetron sputtering, the photolithography technology is ultraviolet photolithography, and the etching process is a wet etching process.

(6) Positioning the nanowire cold cathode 17 growth area by photolithography on the top cathode electrode 15, and then depositing the growth source film 16; the growth source film 16 is zinc, and its thickness is 2.5 μm; the growth source film 16 passes electrons The shape of the growth source film deposited on the top cathode electrode 15 by the beam evaporation method is circular, its diameter is 250 μm, and the distance between the adjacent growth source films 16 is 1250 μm.

(7) A nanowire cold cathode 17 is grown on the growth source film 16 by a thermal oxidation method to obtain a cathode substrate 10 . The growth process of the thermal oxidation method is carried out in a box furnace, the heating rate of the thermal oxidation method is 15° C./min, and Ar can be introduced into the heating process. The heat preservation temperature range of the thermal oxidation process is 450°C, the heat preservation time range is 300min, and Ar can be introduced into the heat preservation process. Finally, cool to room temperature naturally. The resulting nanowires are zinc oxide nanowires.

The anode substrate 20 was produced. As shown in Figures 4(a)-(c) and Figure 5, it is a flow chart of the fabrication of the anode substrate of the nano-cold cathode flat X-ray source of the present invention. The specific production steps are as follows:

(1) Clean and dry the anode substrate 21; the anode substrate 21 is large-area quartz glass.

(2) An anode electrode strip 22 is fabricated on the anode substrate 21; the anode electrode strip 22 is ITO, the thickness of the anode electrode strip 22 is 1 μm, and its shape is a rectangle. The anode electrode strips 22 are deposited on the side of the anode substrate 21 facing the cathode substrate 10 . The anode electrode strip 22 is prepared by vacuum coating technology, photolithography and etching process. The vacuum coating technology is magnetron sputtering, the photolithography technology is ultraviolet photolithography, and the etching process is a wet etching process.

The circular metal target 23 is molybdenum, the thickness of the circular metal target 23 is 500 μm, and its shape is circular. The circular metal target 23 is deposited on the side of the anode electrode strip 22 facing the cathode substrate 10 . The circular metal target 23 is prepared by vacuum coating technology, photolithography and etching process. The vacuum coating technology is magnetron sputtering, the photolithography technology is ultraviolet photolithography, and the etching process is a wet etching process.

S2. Assemble the nano-cold cathode flat X-ray source, as shown in FIG. 6 .

(1) The cathode substrate 10 and the anode substrate 20 are relatively parallel arranged, and the nanowire cold cathode 17 of the cathode substrate 10 faces the anode electrode strips 22 of the anode substrate 20;

(2) Ensure that the bottom cathode electrode strip 12 and the anode electrode strip 22 are perpendicular to each other in space and have intersections;

(3) Ensure that the top cathode electrode 15 and the growth source film 16 provided on the top cathode electrode are located at the intersection.

(4) Ensure that the circular metal target is located at the intersection and corresponds to the growth source film 16 one-to-one.

(5) The high-voltage insulating separator 30 is arranged at the edges of the cathode substrate 10 and the anode substrate 20 to isolate and fix the two. The high-voltage insulating spacer 30 is made of ceramics, and its height is 5 mm.

As shown in Fig. 6, the structure in this patent realizes the addressing function through the vertical arrangement of the anode electrode and the cathode electrode, there is no exposed gate electrode on the cathode substrate, and the bottom cathode electrode strip is buried in the insulating layer at the same time Under this condition, the device discharge problem can be effectively reduced.

Example 2

The structure of the nano-cold cathode flat X-ray source is basically the same as that of Example 1, the difference is that, as shown in FIG. 7 , the growth source film 16 can completely cover the top cathode electrode 15 to prevent high voltage discharge at the edge of the top cathode electrode 15 .

Example 3

The manufacturing method of the flat-panel X-ray source based on the X-ray micro-pixel unit is basically the same as that of Embodiment 1, except that,

The cathode substrate 10 was produced.

(1) The cathode substrate 11 is a large-area silicon wafer.

(2) The bottom cathode electrode strip 12 is Cr. The bottom cathode electrode strip 12 has a thickness of 0.1 μm,

(3) The insulating film as the insulating layer 13 is composed of a silicon nitride insulating film; the thickness of the insulating layer is 1 μm;

(4) The top cathode electrode 15 is Cr, and the thickness of the top cathode electrode 15 is 0.1 μm;

(5) Positioning the growth area of the nanowire cold cathode 17 on the top cathode electrode 15 by photolithography, and then depositing the growth source film 16; the growth source film 16 is copper, and its thickness is 0.3 μm; the diameter of the growth source film is 5 μm, and the distance between the adjacent growth source films 16 is 50 μm.

(6) The growth process of the thermal oxidation method is carried out in a box furnace, the heating rate of the thermal oxidation method is 1° C./min, and Ar can be introduced into the heating process. The holding temperature range of the thermal oxidation process is 600 °C, and the holding time range is 600 min.

The anode substrate 20 was produced.

(1) The anode substrate 21 is a large-area ceramic substrate.

(2) The anode electrode strip 22 is AZO, and the thickness of the anode electrode strip 22 is 0.1 μm.

The circular metal target 23 is tungsten, and the thickness of the circular metal target 23 is 0.2 μm.

S3, assembling a nano-cold cathode flat X-ray source.

(1) The high-voltage insulating spacer 30 is made of insulating plastic, and its height is 0.5 mm.

Example 4

The manufacturing method of the flat-panel X-ray source based on the X-ray micro-pixel unit is basically the same as that of Embodiment 1, except that,

The cathode substrate 10 was produced.

(1) The cathode substrate 11 is a large area glass.

(2) The bottom cathode electrode strip 12 is Ti. The bottom cathode electrode strip 12 has a thickness of 2 μm,

(3) The insulating film as the insulating layer 13 is composed of an aluminum oxide insulating film; the thickness of the insulating layer is 5 μm;

(4) The top cathode electrode 15 is Ti, and the thickness of the top cathode electrode 15 is 2 μm;

(5) The growth source film 16 is titanium, and its thickness is 5 μm; the diameter of the growth source film is 500 μm, and the distance between the adjacent growth source films 16 is 50 μm.

(6) The growth process of the thermal oxidation method is carried out in a box furnace, the heating rate of the thermal oxidation method is 30° C./min, and Ar can be introduced into the heating process. The holding temperature range of the thermal oxidation process is 300°C, and the holding time range is 20 min.

The anode substrate 20 was produced.

(1) The anode substrate 21 is a large-area silicon wafer.

(2) The anode electrode strip 22 is LTFO, and the thickness of the anode electrode strip 22 is 2 μm.

The circular metal target 23 is tungsten, and the thickness of the circular metal target 23 is 1000 μm.

S3, assembling a nano-cold cathode flat X-ray source.

(1) The high-voltage insulating spacer 30 is made of insulating plastic, and its height is 100 mm.

Comparative Example 1

As shown in FIG. 8 , the difference between this comparative example and Example 1 is that the comparative example cathode substrate 110 of this comparative example only includes the comparative example cathode substrate 111 , the comparative example cathode electrode strips 112 and the comparative example growth source film 113 . The comparative anode substrate 120 includes only the comparative anode substrate 121 and the comparative anode metal target electrode strips 122 . The specific structure is as follows:

The nano-cold cathode flat X-ray source includes a comparative cathode substrate 110 , a comparative anode substrate 120 , and a comparative high-voltage insulating separator 130 . The comparative example cathode substrate 110 and the comparative example anode substrate 120 are arranged in parallel and opposite to each other, the comparative example high-voltage insulating separator 130 is arranged between the comparative example cathode substrate 110 and the comparative example anode substrate 120, and the comparative example cathode substrate 110 and the comparative example anode substrate 120 are arranged. The anode substrates 120 of the comparative example were fixed apart from each other. There is a certain distance between the comparative example cathode substrate 110 and the comparative example anode substrate 120 .

The comparative example cathode substrate 110 includes a comparative example cathode substrate 111, two or more comparative example cathode electrode strips 112 arranged in parallel on the comparative example cathode substrate 111, and a plurality of comparative example growth source films independently provided on the cathode electrode strips. 113. The cathode electrode strips 112 of the comparative example are arranged parallel to each other on the side of the cathode substrate 111 of the comparative example facing the anode substrate 120 of the comparative example. The plurality of comparative example growth source films 113 are arranged on the comparative example cathode electrode strips 112 in the form of an array. A nanowire cold cathode 114 of a comparative example is grown on the growth source film 113 of the comparative example in a direction perpendicular to the growth source film 113 of the comparative example. The comparative example cathode substrate 111 may be large area glass. The comparative example cathode electrode strip 112 was ITO. The cathode electrode strip 112 of the comparative example has a thickness of 1 μm and a rectangular shape. The cathode electrode strip 112 of the comparative example was prepared by metal shadow mask and vacuum coating technology. The growth source film 113 of the comparative example is prepared from zinc, and the thickness of the growth source film 113 of the comparative example is 1.2 μm. The comparative example growth source film 113 may be deposited on the comparative example cathode electrode strips 112 by electron beam evaporation. The growth source films 113 of the comparative example are circular in shape and have a diameter of 250 μm, and the distance between the adjacent growth source films 113 of the comparative example is 5 times the diameter. The nanowire cold cathode 114 of the comparative example obtained by the growth of the above-mentioned comparative example growth source film 113 is a zinc oxide nanowire.

The comparative example anode substrate 120 includes a comparative example anode substrate 121 and two or more comparative example anode metal target electrode strips 122 arranged on the comparative example anode substrate 121 in parallel. The anode metal target electrode strip 122 of the comparative example is disposed on the side of the anode substrate 121 of the comparative example facing the cathode substrate 110 of the comparative example. Each of the anode metal target electrode strips 122 of the comparative example and each of the cathode electrode strips on the cathode substrate vertically intersect in space and have an intersection point, and the growth source film 113 of the comparative example is located at the intersection point.

The comparative example anode substrate 121 may be large area glass. The anode metal target electrode strip 122 of the comparative example is a molybdenum metal conductive film, the thickness of the anode metal target electrode strip 122 of the comparative example is 1 μm, and its shape is a rectangle. The comparative anode metal target electrode strips 122 are deposited on the side of the comparative anode substrate 121 facing the comparative cathode substrate 110 . The deposition method is electron beam evaporation method.

The high-voltage insulating spacer 130 of the comparative example is made of glass, and its height is 50 mm.

Device discharge test:

By arbitrarily selecting an anode electrode strip/anode metal target electrode strip and applying a high voltage voltage, the applied voltage is 35kV. / The intersection of the anode metal target electrode strip and the cathode electrode strip will generate X-rays, so that X-rays can be emitted point by point.

The discharge problem of the device is reflected by the highest anode voltage value under stable operation. A high anode voltage means less discharge.

Example The highest working anode voltage value of the device Example 1 28kV Example 2 30kV Example 3 25kV Example 4 26kV Comparative Example 1 15kV

From the above data, it can be seen that the anode voltage values of Examples 1 to 4 are much higher than the anode voltage value of Comparative Example 1. The reason is that in Comparative Example 1, due to the exposed cathode electrode, it will easily lead to the electrode in high voltage operation. The problem of edge discharge, which damages the device, leads to insufficient anode voltage, and cannot achieve transmission imaging of high-density tissue and metal materials. The interference to the original pixels causes the flat-panel X-ray source to have no spatial resolution and cannot form a true X-ray micro-pixel unit array.

In this application, addressing is realized by the spatial vertical arrangement of the anode electrode and the cathode electrode. At the same time, the discharge position of the top cathode electrode 15 mostly appears at the edge of the top cathode electrode 15. Covering the top cathode electrode 15 with the growth source film 16 is equivalent to aligning the top cathode electrode 15. The edge of the cathode electrode 15 plays a protective role to reduce the discharge problem of the device. A circular metal target is set on the anode electrode strip, so that no X-rays are generated in other linear areas outside the disk area, and the pixels emit light independently of each other. When the number of arrays increases, the gap between the pixels can still be maintained. independent of each other, allowing the flat panel X-ray source to have spatial resolution.

Obviously, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the embodiments of the present invention. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (10)

1. A flat-panel X-ray source based on an X-ray micro-pixel unit, comprising a cathode substrate, an anode substrate and a high-voltage insulating spacer; the cathode substrate and the anode substrate are relatively parallel to each other, and the high-voltage insulating spacer is disposed on the between the cathode substrate and the anode substrate to isolate the two, characterized in that: The cathode substrate includes a cathode substrate, two or more bottom cathode electrode strips arranged in parallel on the cathode substrate, an insulating layer covering the bottom cathode electrode strips, and the bottom cathode electrode strips are fabricated in the insulating layer to make the bottom cathode electrode strips. Partially exposed etched through holes, a top cathode electrode fabricated on the insulating layer, a growth source film disposed on the top cathode electrode, on which a nanowire cold cathode is grown, and the top cathode an electrode is connected to the bottom cathode electrode strip through the etched through hole; The anode substrate includes an anode substrate, two or more anode electrode strips arranged in parallel on the anode substrate, and a circular metal target fabricated on the anode electrode strips, Each of the anode electrode strips and each of the bottom cathode electrode strips are vertically intersected in space and have an intersection, the top cathode electrode and the growth source film are located at the intersection, and the top cathode electrodes are arranged in an array are arranged on the bottom cathode electrode strips in the form of, the circular metal targets are located at the intersections, the circular metal targets are arranged in an array on the anode electrode strips, the growth source film An X-ray micro-pixel unit is formed with the circular metal target. 2. The flat-panel X-ray source based on an X-ray micro-pixel unit according to claim 1, wherein the nanowire cold cathode is zinc oxide nanowire, copper oxide nanowire, tungsten oxide nanowire, molybdenum oxide nanowire wire, iron oxide nanowires, titanium oxide nanowires, or tin oxide nanowires. 3 . The flat-panel X-ray source based on an X-ray micro-pixel unit according to claim 1 , wherein the shape of the growth source film is a symmetrical figure, and the diameter or side length of the growth source film is 5 μm-500 μm. 4 . . 4 . The flat-panel X-ray source based on an X-ray micro-pixel unit according to claim 3 , wherein the spacing between the adjacent growth source films is 0.1-10 times the diameter or the side length. 5 . 5 . The flat-panel X-ray source based on an X-ray micro-pixel unit according to claim 1 , wherein the bottom cathode electrode strip and the top cathode electrode have thicknesses ranging from 0.1 μm to 2 μm, and the top The shape of the cathode electrode is circular or polygonal. 6 . The flat-panel X-ray source based on an X-ray micro-pixel unit according to claim 1 , wherein the anode electrode strip has a thickness ranging from 0.1 μm to 2 μm. 7 . 7 . The flat-panel X-ray source based on an X-ray micro-pixel unit according to claim 1 , wherein the circular metal target has a thickness of 0.2 μm-1000 μm. 8 . 8. A preparation method of a flat-panel X-ray source based on an X-ray micro-pixel unit, characterized in that, comprising the following steps: S1. Make cathode substrate and anode substrate: The steps of cathode substrate are: making the bottom cathode electrode strip on the cathode substrate; covering the bottom cathode electrode strip with an insulating layer; etching the insulating layer to form etched through holes on the bottom cathode electrode strip; forming a top cathode electrode connected to the bottom cathode electrode strip on the etched through hole; depositing a growth source film; Thermal oxidation of the growth source film to grow a nanowire cold cathode to obtain a cathode substrate; The preparation steps of the anode substrate are: Making anode electrode strips on the anode substrate; Making a circular metal target array on the anode electrode strip to obtain an anode substrate; S2. Assembly: The cathode substrate and the anode substrate prepared by the above steps are relatively parallel arranged, the nanowire cold cathode on the cathode substrate faces the circular metal target on the anode substrate, and the growth source film corresponds to the circular metal target one-to-one; A high-voltage insulating separator is used to isolate and fix the cathode substrate and the anode substrate, and it is ensured that each anode electrode strip and each bottom cathode electrode strip are spatially perpendicular to each other and have a cross point, the top cathode electrode and the Both the growth source film and the circular metal target are located at the intersection. 9. preparation method according to claim 8 is characterized in that, described thermal oxidation method comprises heating process and insulation process, and the heating rate of heating process is 1 ℃/min-30 ℃/min; The insulation temperature of insulation process is 300 ℃-600 ℃, the holding time is 1min-600min, and the temperature is naturally cooled to room temperature after the heat preservation. 10 . The preparation method according to claim 9 , wherein one or more combined gases of Ar, H ₂ , N ₂ , and O ₂ are introduced into the temperature-raising process and the heat-retaining process. 11 .

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