JP5283053B2 - Field emission electron source - Google Patents

Description

  The present invention relates to a field emission electron source that emits electrons from a field emission cathode by field emission.

  Electron beams are used in many fields such as medical, industrial, and analytical purposes. For example, in addition to being used for pattern evaluation purposes such as inspection and measurement of fine patterns of semiconductor devices, it is used for various applications from material evaluation to cell morphology observation (Patent Documents 1 and 2). Further, X-rays are generated when an electron beam collides with an X-ray target such as a metal or a fluorescent material (Patent Documents 2 and 3).

By the way, among the electron sources that generate the electron beam, many field emission electron sources have been proposed, and it is abbreviated to list patent document numbers. In either case, a field emission cathode and an anode are arranged to face each other. In most cases, the electron beam is emitted from the cathode toward the anode.
JP 2001-338600 A JP2003-1000024 Special Table 2002-517882

  The present invention provides a field emission electron source having a novel structure that can be used in various fields such as medical use, industrial use, analysis use, and the like in a manner different from the conventional one.

  A field emission electron source according to the present invention includes an anode to which a high potential is applied, and an annular cathode that is arranged in a ring around the anode and emits an electric field by applying a high potential to the anode. It is.

  This anode is preferably axial.

  One or more annular cathodes may be provided.

  In the present invention, field electrons can be emitted in a circular or annular pattern from the annular cathode to the periphery of the anode by applying a high potential to the anode, and can be expected to be used in many fields such as medical, industrial, and analytical purposes. . The shape of the anode is not limited to a spherical shape, an elliptical shape, a rod shape, a planar shape, a linear shape, or the like.

  Further, the anode is formed in various shaft shapes such as a rod shape, a linear shape, an elongated substrate shape, a columnar shape, a prismatic shape, a needle shape, etc., and an annular, preferably an annular cathode is disposed around the anode, for example, the radial direction of the annular cathode If the metal electron irradiation object is allowed to pass while the inner through-hole is in contact with the axial anode, the electron irradiation object is irradiated with electrons from the entire periphery in an oblique front direction before passing through the annular cathode, Directly below the annular cathode, electrons can be irradiated to the entire periphery from directly above the object to be irradiated with electrons, and after passing through the annular cathode, the entire periphery can be irradiated to the entire periphery of the electron irradiation object. Thereby, it is possible to perform three-dimensional electron irradiation instead of electron irradiation limited to one direction on the electron irradiation object. When this electron irradiation object is a long object along the axial anode, it is possible to irradiate the entire periphery three-dimensionally without moving it.

  In addition, by arranging an object that can transmit electrons between the annular cathode and the anode, the object can be irradiated with electrons. For example, a resin or the like that is cured by electron irradiation can be formed into a cylindrical shape, and the cylindrical resin can be disposed between the annular cathode and the anode to be cured.

  An electron acceleration means may be disposed between the annular cathode and the anode.

  Moreover, you may accelerate an electron according to the distance from an annular cathode to an anode.

  The annular cathode may be solid or hollow.

  In the present invention, an electron shielding member that shields electrons from the annular cathode may be arranged around the annular cathode, preferably in an annular plate shape or a cylindrical shape. In such a case, electrons from the annular cathode can be emitted to any position on the axial anode, which is preferable.

  In the present invention, the electron shielding member may be disposed at least at two positions on the front and rear sides of the annular cathode. In such a case, it is preferable that electrons can be emitted to an arbitrary position on the axial anode by the electron shielding member more accurately.

  In the present invention, the two electron shielding members may be provided in an annular shape on the outer peripheral side of the annular cathode. In such a case, it is preferable because the electron shielding member can be easily arranged.

  In the present invention, the electron shielding member may be capable of adjusting the distance from the annular cathode and / or adjusting the inner diameter. In such a case, it is preferable that the electron emission range onto the axial anode can be accurately controlled by the electron shielding member.

  In the present invention, electrons can be arbitrarily irradiated by arranging a plurality of the above-described annular cathodes on the shaft-like anode at a distance from each other, and appropriately adjusting the shielding of electrons from each with the electron shielding member. You may do it.

  According to the present invention, it is possible to provide a field emission electron source having a novel structure for medical use, industrial use, analysis use and the like.

  Hereinafter, a field emission electron source according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1 is a perspective view of the field emission electron source of the embodiment, FIG. 2 is a side view of the field emission electron source of FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG. FIG. 1 shows a connection state of a power supply to a field emission electron source, and FIGS. 2 and 3 show a state where electrons are emitted by field emission.

Referring to these drawings, a field emission electron source 10 according to an embodiment has an axial anode 12 having a constant outer diameter and extending linearly in the axial direction, and an annular shape, preferably around the axial anode 12. A field emission type annular cathode 14 arranged in an annular shape with the axial anode 12 as a circle center. The annular cathode 14 is disposed at the axial center of the axial anode 12 . Ring-shaped cathode 14 is provided with a carbon film 16 on the surface thereof. The carbon film 16 has fine nanometer-order projections such as carbon nanotubes, carbon nanowalls, carbon nanofibers, diamond-like carbon, amorphous diamond, crystalline diamond, graphite, fullerene, and acicular carbon film. The electric field can be emitted by applying a high electric field between the electrode 12 and the anode 12. A high potential is applied to the axial anode 12 from a DC power source 18. A negative potential is applied to the annular cathode 14 from the DC power supply 20. A ground potential may be applied to the annular cathode 14.

  In the field emission electron source 10, when a high potential is applied to the axial anode 12 from the DC power supply 18, electrons are emitted from the annular cathode 14 to the axial anode 12 by field emission. In FIG. 2, the electron emission pattern extends from the annular cathode 14 to both axial ends from the axial center of the axial anode 12, and in FIG. 3, around the axial anode 12 radially inward from the annular cathode 14. Has reached.

  In the field emission electron source 10, if an electron irradiation target for medical use, industrial use, analysis use or the like is arranged inside the annular cathode 14, the electron irradiation target is irradiated with electrons from the annular cathode 14 at a time. Can do. If the axial anode 12 is an X-ray target, X-rays can be generated from the entire surface.

  A field emission electron source according to another embodiment of the present invention will be described with reference to FIGS. In this embodiment, an electron shielding member 24 that shields electrons from the annular cathode 14 is provided around the axial anode 12 in an annular plate shape. The electron shielding member 24 is disposed at two locations around the axial anode 12 with the annular cathode 14 sandwiched in the axial direction. The electron shielding member 24 is applied with the same or substantially the same potential as the annular cathode 14.

  Assuming that the pair of electron shielding members 24 has an axial distance D and an inner diameter R, in the case of the orbit indicated by the solid line 26 among the electrons from the annular cathode 14, the electrons are not shielded by the electron shielding member 24 but are emitted to the axial anode 12. In the case of the trajectory indicated by the broken line 28, the electrons are shielded by the shielding electrode 24 and are not emitted to the axial anode 12. The electron irradiation region S on the axial anode 12 can be controlled by adjusting the expansion / contraction of the axial distance F and the inner diameter R of the electron shielding member 24.

  The shape of the electron shielding member 24 is an annular plate in FIGS. 4 and 5, but the shape of the electron shielding member 24 is not limited to the annular plate shape, for example, a cylindrical shape such as the electron shielding member 24a shown in FIG. But you can. Further, the electron shielding members 24 shown in FIGS. 4 to 6 are a pair and can move on the shaft-like anode 12 in the axial direction independently of each other. However, as shown in FIG. May be connected by a connecting member 30 on the outer side in the radial direction of the annular cathode 14 so that both electron shielding members 24 are moved in the axial direction in synchronization with the axial anode 12.

  Referring to FIG. 8, another embodiment will be described. In this field emission electron source, the end 12a of the axial anode 12 has a conical shape, and an annular cathode 14 is disposed around the end 12a. The electron shielding member 24 is disposed so as to surround the annular cathode 14 from the outside in the radial direction. In this field emission type electron source, the electron beam 26 radiated from the annular cathode 14 irradiates the end 12 a of the axial anode 12 without being shielded by the electron shielding member 24, and the electron beam 28 is shielded by the electron shielding member 24. Will be. Then, X-rays can be generated from the conical end portion 12 a by the electron beam 26 that has irradiated the end portion 12 a of the axial anode 12.

  The present invention is not limited to the above-described embodiment, and includes various changes or modifications within the scope described in the claims.

FIG. 1 is a perspective view of a perspective view of a field emission electron source according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the field emission electron source of FIG. 3 is a cross-sectional view taken along line AA in FIG. FIG. 4 is a perspective view of a field emission electron source according to another embodiment of the present invention. FIG. 5 is a cross-sectional view of the field emission electron source of FIG. FIG. 6 is a view showing a modification of the electron shielding member. FIG. 7 is a cross-sectional view of a field emission electron source according to still another embodiment of the present invention. FIG. 8 is a cross-sectional view of a main part of a field emission electron source according to still another embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Field emission type electron source 12 Axial anode 14 Annular cathode 16 Carbon film 24 Electron shielding member

Claims (6)

A field emission electron source comprising: an anode to which a high potential is applied; and an annular cathode that is annularly arranged around the anode and emits an electric field by applying a high potential to the anode,
The anode has a solid axial shape, and the annular cathode is arranged in an annular shape with the axial anode as a circle center, and is arranged at a central position in the axial direction of the axial electrode. Type electron source. 2. The field emission electron source according to claim 1 , wherein an electron shielding member for shielding electrons from the annular cathode is disposed around the annular cathode. 3. The field emission electron source according to claim 2 , wherein the electron shielding member is arranged in an annular plate shape or a cylindrical shape. 4. The field emission electron source according to claim 3 , wherein the electron shielding members are arranged at least at two positions on the front and rear sides of the annular cathode. 5. The field emission electron source according to claim 4 , wherein the two electron shielding members are integrally connected on the outer peripheral side of the annular cathode. The electron shield member, and allows perspective movement and / or inner scaling adjustment from the annular cathode, field emission electron source according to any one of claims 1 to 5, characterized in that.

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