A cold cathode flat panel x-ray source with a floating electrode guard ring and a method of manufacture

Abstract

This invention discloses a cold cathode flat-panel X-ray source with a suspended electrode-type protective ring and its fabrication method. The structure includes a flat-panel cold cathode electron source, a metal transmission target anode, and leads. The cathode substrate of the flat-panel cold cathode electron source is arranged parallel to the anode substrate of the metal transmission target anode. The leads are connected to the outer edge of the flat-panel cold cathode electron source. The structure also includes a suspended electrode-type protective ring and a ring voltage power supply. The ring voltage power supply is connected between the leads and the suspended electrode-type protective ring, which is positioned above the leads and close to at least one side of the edge of the flat-panel cold cathode electron source. This invention, by applying voltage to the protective ring to adjust the local electric field distribution, avoids discharge of the electrodes on the cathode under high anode voltage, thus solving the problem of partial discharge in traditional flat-panel X-ray sources and achieving stable operation of the flat-panel X-ray source under high voltage.

Description

Technical Field

[0001] This invention relates to the field of vacuum microelectronic device technology, specifically to a cold cathode flat X-ray source with a suspended electrode-type protective ring and its preparation method. Background Technology

[0002] Cold cathode flat-panel X-ray sources utilize large-area nano-cold cathodes as the cold cathode electron source, enabling the integration of numerous miniature X-ray sources. Devices using cold cathode flat-panel X-ray sources can achieve large-area, uniform, and high-resolution addressable X-ray emission. Currently, cold cathode flat-panel X-ray sources represent a transformation from discrete devices in traditional X-ray sources to large-scale integrated devices, and can be used to develop new systems such as rapid, scan-free conformal CT and conformal radiotherapy, showing significant application prospects in medical diagnosis, metal flaw detection, and security inspection.

[0003] Reported planar X-ray source devices can be divided into two types: diode structure and plateau structure. Diode structure planar X-ray source devices consist of a nanocold cathode and a metal target, and are generally used to generate uniform, large-area X-ray radiation. Plateau X-ray sources consist of an addressable cold cathode array and a metal target. By controlling the voltage of the grid and cathode, X-rays can be emitted at selected locations, thereby achieving large-area addressable and controllable emission.

[0004] In 2011, Grant et al. proposed a planar X-ray source (EJ Grant, et al. in Proceedings of SPIE, the International Society for Optical Engineering / Proceedings of SPIE, Mar, pp. 796108–796108, (2011)), whose structure includes a substrate, a carbon nanotube electron source, a grid, a focusing electrode, an anode target, and a collimator. However, carbon nanotubes are difficult to fabricate uniformly on a large scale, preventing the device from achieving addressed emission. In 2021, Cao et al. used a ZnO nanocold cathode electron source and a molybdenum thin-film transmission anode target to realize a fully vacuum-sealed addressable planar X-ray source (XQ Cao, et al. Applied Physics Letters, 119, 1-6, (2021)). This device can achieve addressed emission by applying a gate voltage and achieved X-ray imaging at an anode voltage of 21 kV and a gate voltage of 140 V. However, due to the large number of electrode strips fabricated in the device structure of planar X-ray sources, local electric field concentration can easily occur at the edges of the electrode strips, making them prone to discharge under high voltage operation. Therefore, the increase of the anode voltage of large-area cold cathode planar X-ray sources is limited. Overcoming the discharge problem caused by the electrode structure of planar X-ray sources is the key to achieving stable and long-life operation of the device under high voltage.

[0005] To overcome the problem of edge discharge easily caused by flat X-ray sources under high voltage, a patented method has been proposed to prepare a metal thin film protective ring by shadow mask evaporation. However, the insulating layer prepared by the thin film process has low withstand voltage, which limits the magnitude of the voltage applied to the protective ring and thus limits the protective effect. Summary of the Invention

[0006] To overcome the problem in existing cold cathode flat X-ray sources that sharp edges generated during microfabrication processes of the gate or cathode electrodes can easily lead to discharge, thus affecting the stability of operation under high voltage and the lifetime of cathode nanowires, this invention provides a cold cathode flat X-ray source with a suspended electrode-type protective ring and its preparation method.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] This invention provides a cold cathode flat-panel X-ray source with a suspended electrode-type protective ring, comprising a flat-panel cold cathode electron source, a metal transmission target anode, and leads. The cathode substrate of the flat-panel cold cathode electron source is arranged parallel to the anode substrate of the metal transmission target anode. The leads are connected to the outer edge of the flat-panel cold cathode electron source. The invention also includes a suspended electrode-type protective ring and a ring voltage power supply, wherein the ring voltage power supply is connected between the leads and the suspended electrode-type protective ring, and the suspended electrode-type protective ring is disposed above the leads and close to at least one side of the edge of the flat-panel cold cathode electron source.

[0009] Furthermore, the suspended electrode protection ring includes a fixing frame and a metal suspended electrode protection ring, wherein the fixing frame is disposed outside the flat plate cold cathode electron source, the metal suspended electrode protection ring is located directly above the lead, one end is fixed on the fixing frame, and the other end is close to the outer edge of the flat plate cold cathode electron source in the vertical direction, and the metal suspended electrode protection ring is electrically connected to an external fixed potential through a conductive material.

[0010] Furthermore, both the flat plate cold cathode electron source and the metal transmission target anode are located within the suspended electrode fixed side of the metal suspended electrode protection ring.

[0011] Furthermore, the metal suspended electrode protection ring is made of one or more metals including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0012] Furthermore, the mounting bracket is made of one or more metals selected from tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0013] Furthermore, the cathode and gate electrodes of the planar cold cathode electron source are made of conductive thin films of one or more metals or metal oxides, including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0014] Furthermore, the flat-plate cold cathode electron source is made of a one-dimensional nanocold cathode, which includes carbon nanotubes, zinc oxide nanowires, and copper oxide nanowires.

[0015] The second invention also provides a method for preparing a cold cathode flat X-ray source with a suspended electrode-type protective ring, comprising the following steps: S1 fabricates a cathode electrode, an insulating layer, and a gate electrode layer on a substrate, and uses ultraviolet lithography and etching processes to prepare a gate structure, growing a planar cold cathode electron source in the cathode region of the gate structure. S2 is used to prepare a metal transmission target anode; S3 is used to prepare a suspended electrode-type protective ring; S4 fixes the suspended electrode type protective ring above the lead wire; S5 encapsulates the flat cold cathode electron source, the metal transmission target anode, the suspended electrode-type protective ring, and the lead wires. S6 connects the toroidal voltage power supply between the lead and the suspended electrode type protection ring.

[0016] Furthermore, the preparation method of the suspended electrode type protective ring includes CNC machine tool processing, laser cutting, and 3D printing.

[0017] Furthermore, the method for fixing the suspended electrode-type protective ring above the lead wire includes bonding, sintering, mechanical fixing, and fusion welding.

[0018] Compared with the prior art, the beneficial effects of the technical solution of the present invention are: This invention relates to a cold cathode flat-panel X-ray source with a suspended electrode-type protective ring. This design avoids the drawback of traditional flat-panel X-ray sources where partial discharge easily occurs at the electrode edges on the cathode substrate. By applying a locally modulated electric field through the protective ring, the concentrated electric field in the overlapping area between the anode edge and the cathode lead is reduced, preventing discharge at sharp corners and thus achieving stable operation under high voltage. The suspended electrode-type protective ring can be fabricated independently of the device, avoiding the microfabrication process contamination introduced during the fabrication of protective rings in traditional semiconductor devices. This invention can increase the operating voltage of the cold cathode flat-panel X-ray source, thereby significantly increasing the device's emission dose. Furthermore, it solves the problem of electrode damage due to discharge on the gate and cathode substrate, thus improving the lifespan, stability, and reliability of the cold cathode flat-panel X-ray source. This is of great significance for the multi-scenario application of cold cathode flat-panel X-ray sources. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a cold cathode flat X-ray source with a suspended electrode-type protective ring having a fully encircling structure, provided as an embodiment of the present invention.

[0020] Figure 2 Provided for embodiments of the present invention Figure 1 The left view of a cold cathode flat-panel X-ray source with a suspended electrode-type protective ring having a fully encircling structure is shown.

[0021] Figure 3 A bottom view of a cold cathode flat X-ray source with a suspended electrode-type protective ring having a partially surrounding structure, provided in an embodiment of the present invention.

[0022] Figure 4 This is a schematic diagram of the overall structure of a strip-shaped flat grid cold cathode plate X-ray source with a suspended electrode-type protective ring and finger-addressing, provided as an embodiment of the present invention.

[0023] Figure 5 Provided for embodiments of the present invention Figure 4 The front view of a strip-grid cold cathode flat X-ray source with a suspended electrode type guard ring and finger-addressable design.

[0024] Figure 6 Provided for embodiments of the present invention Figure 4 The left view of a strip-grid cold cathode flat X-ray source with a suspended electrode type guard ring and finger-addressable design.

[0025] Figure 7 Provided for embodiments of the present invention Figure 4 The method for fabricating a strip-shaped flat grid cold cathode plate X-ray source with a suspended electrode type protective ring and finger addressing is shown.

[0026] In the figure, 1 is the lead wire, 2 is the glass substrate, 3 is the suspended electrode type protective ring, 4 is the flat plate cold cathode electron source, 5 is the metal transmission target anode, 6 is the isolator, 7 is the high voltage power supply, 8 is the anode lead wire, 9 is the cathode lead wire, 10 is the gate lead wire, 11 is the gate voltage, 12 is the zinc oxide nanowire, 13 is the indium tin oxide transparent electrode, 14 is zinc, 15 is the ring gate, 16 is the gate electrode strip, 17 is the ring voltage power supply, and 18 is the sintered low glass powder. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0028] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] In a first embodiment of the present invention, a cold cathode flat-panel X-ray source with a suspended electrode-type protective ring is provided, comprising: The system includes a flat plate cold cathode electron source 4, a metal transmission target anode 5, and a lead wire 1. The cathode substrate of the flat plate cold cathode electron source 4 is arranged parallel to the anode substrate of the metal transmission target anode 5. The lead wire 1 is connected to the outer edge of the flat plate cold cathode electron source 4. The system also includes a suspended electrode type protective ring 3 and a ring voltage power supply 17. The ring voltage power supply 17 is connected between the lead wire 1 and the suspended electrode type protective ring 3. The suspended electrode type protective ring 3 is arranged above the lead wire 1.

[0031] Optionally, the suspended electrode type protective ring 3 can be configured according to the electrode structure and discharge position, surrounding the flat plate cold cathode electron source 4 (e.g., Figure 1 and Figure 2 As shown), three sides (such as) Figure 3 As shown), on both sides or one side, covering the lead 1 above the edge of the flat plate cold cathode electron source 4. When surrounding both sides, the suspended electrode type protective ring 3 can be divided into two independent areas and connected to potentials respectively, so as to avoid large-area uneven light output caused by insufficient cathode uniformity. Alternatively, they can be connected by rounded corners on adjacent sides.

[0032] Furthermore, the suspended electrode type protection ring 3 includes a fixing frame and a metal suspended electrode protection ring, wherein the fixing frame is disposed on the outside of the flat plate cold cathode electron source 4, and the metal suspended electrode protection ring is located directly above the lead wire, with one end fixed to the fixing frame and the other end close to the outer edge of the flat plate cold cathode electron source 4 in the vertical direction. The metal suspended electrode protection ring is electrically connected to an external fixed potential through a conductive material.

[0033] In this embodiment, the suspended electrode protection ring 3 includes a fixing frame and a metal suspended electrode protection ring. An adjustable ring voltage is used to control the electric field strength in the sensitive area of ​​the electrode leads as needed. The outer metal fixing frame extends the electrode edge, which is prone to discharge, to the far end of the substrate to optimize the overall electric field uniformity. The fixing frame maintains sufficient physical distance between the protection ring and the electrode, preventing short circuits and providing a certain ring voltage adjustment margin. The metal suspended electrode protection ring acts as a potential relay point, adjusting the local electric field in the cathode edge region, thereby reducing the probability of discharge. Simultaneously, the protection ring acts as a sacrificial layer, protecting the cathode during high-field discharge.

[0034] Furthermore, both the flat plate cold cathode electron source 4 and the metal transmission target anode 5 are located within the suspended electrode fixed side of the metal suspended electrode protection ring.

[0035] Furthermore, the metal suspended electrode protection ring is made of one or more metals including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0036] Furthermore, the mounting bracket is made of one or more metals selected from tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0037] Furthermore, the cathode and gate electrodes of the flat plate cold cathode electron source 4 are made of conductive thin films of one or more metals or metal oxides, including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0038] Furthermore, the flat plate cold cathode electron source 4 is made of a one-dimensional nanocold cathode, which includes carbon nanotubes, zinc oxide nanowires and copper oxide nanowires.

[0039] In this embodiment, the glass substrate 2 is composed of one or more combinations of silicon wafers, glass, quartz glass, or ceramic substrates, and the silicon wafers, glass, quartz glass, or ceramic substrates are large-area materials.

[0040] In this embodiment, the suspended electrode protective ring 3 is made of one or more of the following metallic materials: Cr, Al, Ti, Cu, ITO, IZO, AZO, FTO, and LTFO. The thickness of the suspended metal electrode protective ring ranges from 0.2 mm to 3 mm. During the fabrication of the suspended metal electrode protective ring, the edges need to be polished as much as possible to avoid burrs that could lead to discharge.

[0041] The second embodiment of the present invention further provides a cold cathode flat-plate X-ray source with a suspended electrode type protective ring based on the first embodiment. In this embodiment, the cold cathode flat-plate X-ray source is an interpolated addressable strip-grid cold cathode flat-plate X-ray source, such as... Figure 4-6 As shown, it includes: The device includes a flat cold cathode electron source 4, a metal transmission target anode 5, and a lead wire 1. The cathode substrate of the flat cold cathode electron source 4 is arranged parallel to the anode substrate of the metal transmission target anode 5. The lead wire 1 is connected to the outer edge of the flat cold cathode electron source 4. The device also includes a suspended electrode type protective ring 3 and a ring voltage power supply 17. The ring voltage power supply 17 is connected between the lead wire 1 and the suspended electrode type protective ring 3. The suspended electrode type protective ring 3 is arranged above the lead wire 1. A support frame maintains a certain distance between the suspended electrode type protective ring 3 and the cold cathode electrode strip. The indium tin oxide transparent electrode 13 and the strip cathode electrode are led to the high and low potentials of the power supply on both sides by leads 1, respectively. Under the combined action of the anode high voltage and the grid and cathode voltages, the zinc oxide nanowire 12 emits electrons that bombard the metal transmission target anode 5, thereby generating addressable X-rays. At this time, the ring voltage power supply 17 connected to the suspended electrode type protective ring 3 will adjust the electric field near the edge electron source to prevent it from becoming a potential breakdown site, and withstand the discharge in the event of breakdown, protecting the flat plate cold cathode electron source 4.

[0042] Furthermore, the suspended electrode type protection ring 3 includes a fixing frame and a metal suspended electrode protection ring, wherein the fixing frame is disposed on the outside of the flat plate cold cathode electron source 4, and the metal suspended electrode protection ring is located directly above the lead wire, with one end fixed to the fixing frame and the other end close to the outer edge of the flat plate cold cathode electron source 4 in the vertical direction. The metal suspended electrode protection ring is electrically connected to an external fixed potential through a conductive material.

[0043] In this embodiment, the suspended electrode protection ring 3 includes a fixing frame and a metal suspended electrode protection ring. An adjustable ring voltage is used to control the electric field strength in the sensitive area of ​​the electrode leads as needed. The outer metal fixing frame extends the electrode edge, which is prone to discharge, to the far end of the substrate to optimize the overall electric field uniformity. The fixing frame maintains sufficient physical distance between the protection ring and the electrode, preventing short circuits and providing a certain ring voltage adjustment margin. The metal suspended electrode protection ring acts as a potential relay point, adjusting the local electric field in the cathode edge region, thereby reducing the probability of discharge. Simultaneously, the protection ring acts as a sacrificial layer, protecting the cathode during high-field discharge.

[0044] Furthermore, both the flat plate cold cathode electron source 4 and the metal transmission target anode 5 are located within the suspended electrode fixed side of the metal suspended electrode protection ring.

[0045] Furthermore, the metal suspended electrode protection ring is made of one or more metals including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0046] Furthermore, the mounting bracket is made of one or more metals selected from tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0047] Furthermore, the cathode and gate electrodes of the flat plate cold cathode electron source 4 are made of conductive thin films of one or more metals or metal oxides, including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

[0048] Furthermore, the flat plate cold cathode electron source 4 is made of a one-dimensional nanocold cathode, which includes carbon nanotubes, zinc oxide nanowires and copper oxide nanowires.

[0049] In this embodiment, the arrangement and specific number of the zinc oxide nanowires 12 are not limited.

[0050] In this embodiment, the glass substrate 2 is composed of one or more combinations of silicon wafers, glass, quartz glass, or ceramic substrates, and the silicon wafers, glass, quartz glass, or ceramic substrates are large-area materials.

[0051] In this embodiment, the suspended electrode protective ring 3 is made of one or more of the following metallic materials: Cr, Al, Ti, Cu, ITO, IZO, AZO, FTO, and LTFO. The thickness of the suspended metal electrode protective ring ranges from 0.5 mm to 2 mm. During the fabrication of the suspended metal electrode protective ring, the edges need to be polished as much as possible to avoid burrs that could lead to discharge.

[0052] The third embodiment of the present invention further discloses a method for preparing a strip-shaped flat-grid cold cathode plate X-ray source with interlocking finger addressing and a suspended electrode type protective ring, based on the first and second embodiments. Figure 7 As shown, it includes the following steps: S1 fabricates a cathode electrode, an insulating layer, and a gate electrode layer on a substrate, and uses ultraviolet lithography and etching processes to prepare a gate structure. A planar cold cathode electron source 4 is grown in the cathode region of the gate structure. S2 is used to prepare the metal transmission target anode 5; S3 prepares a suspended electrode-type protective ring 3; S4 Fix the suspended electrode type protective ring 3 above the lead wire 1; S5 encapsulates the flat plate cold cathode electron source 4, the metal transmission target anode 5, the suspended electrode type protective ring 3, and the lead wire 1. S6 connects the toroidal voltage power supply 17 between the lead 1 and the suspended electrode type protection ring 3.

[0053] Furthermore, the preparation method of the suspended electrode type protective ring 3 includes CNC machine tool processing, laser cutting, and 3D printing.

[0054] Furthermore, the method for fixing the suspended electrode type protective ring 3 above the lead wire 1 includes bonding, sintering, mechanical fixing, and fusion welding.

[0055] The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A cold cathode flat-plate X-ray source with a suspended electrode-type protective ring, comprising a flat-plate cold cathode electron source (4), a metal transmission target anode (5), and a lead wire (1), wherein the cathode substrate of the flat-plate cold cathode electron source (4) is arranged parallel to the anode substrate of the metal transmission target anode (5), and the lead wire (1) is connected to the outer edge of the flat-plate cold cathode electron source (4), characterized in that, It also includes a suspended electrode type protection ring (3) and a ring voltage power supply (17), wherein: the ring voltage power supply (17) is connected between the lead wire (1) and the suspended electrode type protection ring (3), and the suspended electrode type protection ring (3) is located above the lead wire (1) and close to at least one side of the edge of the flat plate cold cathode electron source (4).

2. The cold cathode flat plate X-ray source with a suspended electrode protective ring according to claim 1, characterized in that, The suspended electrode protection ring (3) includes a fixing frame and a metal suspended electrode protection ring. The fixing frame is located outside the flat plate cold cathode electron source (4). The metal suspended electrode protection ring is located directly above the lead (1). One end is fixed to the fixing frame, and the other end is close to the outer edge of the flat plate cold cathode electron source (4) in the vertical direction. The metal suspended electrode protection ring is electrically connected to an external fixed potential through a conductive material.

3. The cold cathode flat plate X-ray source with a suspended electrode protective ring according to claim 2, characterized in that, The flat plate cold cathode electron source (4) and the metal transmission target anode (5) are both within the range of the suspended electrode fixed side of the metal suspended electrode protection ring.

4. The cold cathode flat plate X-ray source with a suspended electrode protective ring according to claim 2, characterized in that, The metal suspended electrode protection ring is made of one or more metals including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

5. The cold cathode flat plate X-ray source with a suspended electrode protective ring according to claim 2, characterized in that, The mounting bracket is made of one or more metals selected from tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

6. The cold cathode flat plate X-ray source with a suspended electrode protective ring according to claim 1, characterized in that, The cathode and gate electrodes of the flat plate cold cathode electron source (4) are made of conductive thin films of one or more metals or metal oxides, including tungsten, molybdenum, chromium, aluminum, zinc, and indium tin oxide.

7. The cold cathode flat plate X-ray source with a suspended electrode protective ring according to claim 1, characterized in that, The flat plate cold cathode electron source (4) is made of a one-dimensional nano cold cathode, which includes carbon nanotubes, zinc oxide nanowires and copper oxide nanowires.

8. A method for preparing a cold cathode flat-plate X-ray source with a suspended electrode-type protective ring, characterized in that, Includes the following steps: S1 fabricates a cathode electrode, an insulating layer and a gate electrode layer on the substrate, and uses ultraviolet lithography and etching processes to prepare a gate structure, and grows a planar cold cathode electron source in the cathode region of the gate structure (4). S2 prepares a metal transmission target anode (5); S3 prepares a suspended electrode type protective ring (3); S4 fixes the suspended electrode type protective ring (3) above the lead wire (1); S5 encapsulates the flat plate cold cathode electron source (4), the metal transmission target anode (5), the suspended electrode type protection ring (3), and the lead wire (1); S6 connects the ring voltage power supply (17) between the lead (1) and the suspended electrode type protection ring (3).

9. The method for preparing a cold cathode flat X-ray source with a suspended electrode protective ring according to claim 8, characterized in that, The preparation method of the suspended electrode type protective ring (3) includes CNC machine tool processing, laser cutting, and 3D printing.

10. The method for preparing a cold cathode flat X-ray source with a suspended electrode-type protective ring according to claim 8, characterized in that, The method of fixing the suspended electrode type protective ring (3) above the lead wire (1) includes bonding, sintering, mechanical fixing, and fusion welding.

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