Electron source, manufacturing method of the same, and electron beam device

Abstract

To provide an electron source which can have sufficient electron emission characteristics even after a certain time elapses from start of emission of electrons, and to provide a manufacturing method of the electron source.SOLUTION: An electron source 100 includes: an electron emission member 10 containing iridium and lanthanoid; a conductive support member 20 which supports the electron emission member 10; and a conductive member 30 disposed between the electron emission member 10 and the support member 20 and in contact with both. In a manufacturing method of the electron source 100, the electron emission member 10 and the support member 20 are joined through the conductive member 30.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electron source, a manufacturing method thereof, an electron beam apparatus, and the like. [Background technology]

[0002] Electron sources are used in electron beam devices such as electron microscopes and semiconductor inspection devices, and include an electron-emitting member. In conventional electron sources, for example, the use of LaB6 or the like as a constituent material of the electron-emitting member has been considered (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 01-007450 Summary of the Invention [Problem to be solved by the invention]

[0004] An electron source may be required to maintain a sufficient amount of electron emission for a certain period of time, and such an electron source is required to have sufficient electron emission characteristics even after a certain period of time has elapsed since the start of electron emission.

[0005] An object of one aspect of the present disclosure is to provide an electron source capable of maintaining sufficient electron emission characteristics even after a certain time has elapsed since the start of electron emission. Another object of the present disclosure is to provide a method for manufacturing such an electron source. Another object of the present disclosure is to provide an electron beam apparatus including such an electron source. [Means for solving the problem]

[0006] The present inventors have found that the bonding strength between the electron-emitting member and the support member can vary greatly depending on the constituent materials of the conductive members in contact with the electron-emitting member and the support member. The present inventors have also found that using an electron-emitting member containing iridium and lanthanoid contributes to obtaining sufficient electron emission characteristics, and that when such an electron-emitting member is supported by a conductive support member, by arranging a conductive member in contact with the electron-emitting member and the support member between the electron-emitting member and the support member, sufficient electron emission characteristics can be obtained even after a certain time has passed since the start of electron emission.

[0007] The present disclosure relates to the following [1] to

[12] etc. [1] An electron source comprising: an electron-emitting member containing iridium and a lanthanoid; a conductive support member supporting the electron-emitting member; and a conductive member in contact with the electron-emitting member and the support member between the electron-emitting member and the support member. [2] The electron source according to [1], wherein the lanthanoid includes at least one selected from the group consisting of lanthanum and cerium. [3] The electron source according to [1] or [2], wherein the molar ratio of the iridium to the lanthanoid in the electron-emitting member is 1.0 or more. [4] The electron source according to any one of [1] to [3], wherein the molar ratio of the iridium to the lanthanoid in the electron-emitting member is 2.0 or more. [5] The electron source according to any one of [1] to [4], wherein the electron-emitting member has a surface having a surface roughness Ra of 0.10 μm or less as a contact surface with the conductive member. [6] The electron source according to any one of [1] to [5], wherein the support member contains at least one selected from the group consisting of tantalum, tungsten, rhenium, and molybdenum. [7] The electron source according to any one of [1] to [6], wherein the support member has an internal space that accommodates at least a part of the electron-emitting member, and the conductive member is in contact with the electron-emitting member and the support member in the internal space. [8] The electron source according to any one of [1] to [7], wherein the conductive member has a thickness of 1 to 50 μm. [9] The electron source according to any one of [1] to [8], wherein the conductive member contains titanium.

[10] The electron source according to [9], wherein the content of titanium in the conductive member is 50 to 90% by volume based on the total volume of the conductive member.

[11] The method for manufacturing an electron source according to any one of [1] to

[10] , wherein the electron-emitting member and the supporting member are joined via the conductive member.

[12] An electron beam device comprising the electron source according to any one of [1] to

[10] . [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to provide an electron source that can maintain sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. According to another aspect of the present disclosure, it is possible to provide a method for manufacturing such an electron source. According to another aspect of the present disclosure, it is possible to provide an electron beam device including such an electron source. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view showing an example of an electron source. [Figure 2] FIG. 2 is an end view taken along line II-II in FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of an electron beam apparatus equipped with an electron source. DETAILED DESCRIPTION OF THE INVENTION

[0010] A numerical range "A or greater" means a range exceeding A and A. A numerical range "A or less" means a range exceeding A and A. In the numerical ranges described in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or both. The materials exemplified in this specification may be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of the multiple substances present in the composition unless otherwise specified. The term "process" does not only refer to an independent process, but also includes processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved. "At least a portion" means part or all of the process.

[0011] The electron source according to this embodiment includes an electron-emitting member containing iridium and a lanthanoid, a conductive support member that supports the electron-emitting member, and a conductive member that is in contact with the electron-emitting member and the support member between the electron-emitting member and the support member.

[0012] According to the electron source of this embodiment, sufficient electron emission characteristics can be obtained even after a certain time has passed since the start of electron emission. In the electron source of this embodiment, in the evaluation of the electron emission characteristics described in the examples to be described later, the current density after 12 hours from the start of electron emission was, for example, 0.5 A / cm. 2 or more (preferably 0.8A / cm 2 More than 1.0A / cm 2 More than 1.2A / cm 2The above and other properties can be obtained. It is presumed that the conductive member firmly bonds the electron-emitting member and the support member due to the reaction between the iridium or lanthanide of the electron-emitting member and the constituent material of the conductive member, so that sufficient electron emission characteristics can be obtained even after a certain time has passed since electron emission began. However, the factors that enable sufficient electron emission characteristics to be obtained even after a certain time has passed are not limited to the above.

[0013] The electron source according to this embodiment can obtain sufficient electron emission characteristics even after a certain time has passed since the start of electron emission in a low vacuum atmosphere, which simplifies the equipment required to maintain the vacuum state.

[0014] The electron source according to this embodiment can be used in a vacuum atmosphere having the following degree of vacuum: -4 Pa or less, 5×10 -5 Pa or less, 1×10 -5 Pa or less, 5×10 -6 Pa or less, or 1×10 -6 The vacuum level of the vacuum atmosphere may be 1×10 Pa or less. -7 Pa or higher, 5×10 -7 Pa or more, or 1×10 -6 From these viewpoints, the degree of vacuum of the vacuum atmosphere may be 1×10 -7 ~1×10 -4 Pa, 1 × 10 -7 ~5×10 -5 Pa, 1 × 10 -7 ~1×10 -5 Pa, 5 × 10 -7 ~1×10 -4 Pa, 5 × 10 -7 ~5×10 -5 Pa, 5 × 10 -7 ~1×10 -5 Pa, 1 × 10 -6 ~1×10 -4 Pa, 1 × 10 -6 ~5×10 -5 Pa or 1 x 10 -6 ~1×10 -5 It may be Pa.

[0015] The electron beam apparatus according to this embodiment includes the electron source according to this embodiment. According to the electron beam apparatus according to this embodiment, even if a malfunction occurs in the electron source of the electron beam apparatus, the electron beam apparatus can be reused by simply replacing the electron source. Examples of electron beam apparatuses include X-ray generators, electron microscopes, semiconductor manufacturing apparatuses, analytical apparatuses (inspection apparatuses: for example, electron probe microanalyzers), and processing apparatuses (for example, electron beam evaporation apparatuses). The electron beam apparatus may include the electron source according to this embodiment as a sealed X-ray source or an open X-ray source, or may include a sealed X-ray tube or an open X-ray tube having the electron source according to this embodiment. The electron beam apparatus according to this embodiment may include a member that is irradiated with electrons emitted from the electron source, and may include a heating means for heating the electron-emitting member of the electron source.

[0016] The electron source according to this embodiment includes an electron-emitting member containing iridium and a lanthanoid. The electron-emitting member may be a long, columnar member. The shape of a cross section of the electron-emitting member perpendicular to the electron emission direction (axial direction of the electron-emitting member) is not particularly limited, and examples thereof include a rectangle (rectangular or square) and a circle (perfect circle, ellipse, etc.). The electron-emitting member may have a tip end that emits electrons (electron beams) and a base end opposite the tip end. The tip end of the electron-emitting member may have a sharpened shape or may be tapered to a point. The tip end of the electron-emitting member may be located at the center of a cross section of the electron-emitting member perpendicular to the electron emission direction.

[0017] Examples of lanthanoids include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. The lanthanoid may contain at least one selected from the group consisting of lanthanum and cerium, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has elapsed since the start of electron emission. The electron-emitting member may contain an iridium-cerium compound (a compound containing iridium and cerium, such as an iridium-cerium alloy) from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has elapsed since the start of electron emission, and from the viewpoint of easily sharpening the tip of the electron-emitting member due to ease of processing, thereby improving resolution. Examples of iridium-cerium compounds include Ir2Ce, Ir3Ce, Ir7Ce2, and Ir5Ce. The electron-emitting member may contain at least one selected from the group consisting of Ir2Ce and Ir7Ce2, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The electron-emitting member may not contain boron, may not contain a boride, and may not contain a rare-earth boride (e.g., a rare-earth hexaboride).

[0018] In the electron-emitting material, the total amount of lanthanoid and iridium, or the total amount of cerium and iridium, may be 50 mol % or more, more than 50 mol %, 70 mol % or more, 80 mol % or more, 90 mol % or more, 92 mol % or more, 95 mol % or more, 98 mol % or more, 99 mol % or more, or substantially 100 mol % based on the total amount of the electron-emitting material, from the viewpoint of easily obtaining sufficient electron-emitting characteristics even after a certain time has passed since the start of electron emission.

[0019] In the electron emitting member, the molar ratio R of iridium to lanthanoid or the molar ratio of iridium to cerium may be in the following range. From the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission, the molar ratio R may be 0.5 or more, 1.0 or more, more than 1.0, 1.5 or more, 2.0 or more, more than 2.0, 2.5 or more, 3.0 or more, more than 3.0, or 3.5 or more. From the viewpoint of adjusting the electron emission characteristics after a certain time has passed since the start of electron emission, the molar ratio R may be 8.0 or less, 7.5 or less, 7.0 or less, 6.5 or less, 6.0 or less, 5.5 or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, 3.0 or less, 2.5 or less, or 2.0 or less. From these viewpoints, the molar ratio R may be 0.5 to 8.0, 0.5 to 5.0, 0.5 to 4.0, 1.5 to 8.0, 1.5 to 5.0, 1.5 to 4.0, 2.5 to 8.0, 2.5 to 5.0, or 2.5 to 4.0.

[0020] The electron-emitting member may contain a metal element other than iridium and lanthanoid. The molar ratio of the metal element other than iridium and lanthanoid may be 1 mol % or less, 0.5 mol % or less, 0.1 mol % or less, 0.05 mol % or less, 0.01 mol % or less, or substantially 0 mol % based on the total amount of the electron-emitting member, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission.

[0021] The electron emitting member may have a surface with a surface roughness Ra in the following range as a contact surface with the conductive member. Since a strong bond is easily obtained due to an increased contact area between the electron emitting member and the conductive member, the surface roughness Ra may be 3.00 μm or less, 2.00 μm or less, 1.00 μm or less, 0.80 μm or less, 0.50 μm or less, 0.45 μm or less, 0.40 μm or less, 0.30 μm or less, 0.20 μm or less, 0.10 μm or less, 0.05 μm or less, 0.03 μm or less, or 0.02 μm or less, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has elapsed since the start of electron emission. The surface roughness Ra may be 0.001 μm or more, 0.005 μm or more, 0.01 μm or more, or 0.02 μm or more, from the viewpoint of adjusting the electron emission characteristics after a certain time has elapsed since the start of electron emission. From these viewpoints, the surface roughness Ra may be 0.001 to 3.00 μm, 0.001 to 0.50 μm, 0.001 to 0.10 μm, 0.005 to 3.00 μm, 0.005 to 0.50 μm, 0.005 to 0.10 μm, 0.01 to 3.00 μm, 0.01 to 0.50 μm, or 0.01 to 0.10 μm. The surface roughness Ra is the arithmetic mean roughness defined in JIS B 0601-2001.

[0022] The length of the electron emitting member in the electron emission direction (axial direction of the electron emitting member) (e.g., the length from the tip to the base end) may be within the following ranges. The length of the electron emitting member may be 100 μm or more, 300 μm or more, 500 μm or more, 800 μm or more, 1000 μm or more, 1200 μm or more, or 1300 μm or more. The length of the electron emitting member may be 5000 μm or less, 4000 μm or less, 3000 μm or less, 2500 μm or less, 2000 μm or less, 1500 μm or less, or 1300 μm or less. From these viewpoints, the length of the electron emitting member may be 100 to 5000 μm, 100 to 3000 μm, 100 to 2000 μm, 500 to 5000 μm, 500 to 3000 μm, 500 to 2000 μm, 1000 to 5000 μm, 1000 to 3000 μm, or 1000 to 2000 μm.

[0023] The electron source according to this embodiment includes a conductive support member that supports the electron-emitting member. The support member is in contact with the conductive member and can support the electron-emitting member via the conductive member.

[0024] Examples of the constituent material (conductive material) of the support member include metal materials, carbon materials, etc. Examples of metal materials include transition metals such as tantalum, tungsten, rhenium, and molybdenum. From the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain period of time has passed since the start of electron emission, the support member may contain a metal material, may contain at least one selected from the group consisting of tantalum, tungsten, rhenium, and molybdenum, or may contain tantalum.

[0025] In the support member, the content of the metal material, the content of the transition metal, or the content of tantalum may be 50 mol% or more, more than 50 mol%, 70 mol% or more, 80 mol% or more, 90 mol% or more, 92 mol% or more, 95 mol% or more, 98 mol% or more, 99 mol% or more, or substantially 100 mol%, based on the total amount of the support member, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain period of time has passed since electron emission began.

[0026] The support member may have a pair of sidewalls extending in the electron emission direction and a bottom extending in a direction perpendicular to the electron emission direction. The pair of sidewalls may be parallel and opposed to each other and may have a pair of main surfaces that are parallel and opposed to each other. The base ends of each of the pair of sidewalls in the electron emission direction may be connected to the bottom. The support member may have an internal space that accommodates at least a portion of the electron emitting member (e.g., a portion of the electron emitting member on the base end side). The internal space may be partitioned by the pair of sidewalls and the bottom. Both ends of the support member in a direction perpendicular to the electron emission direction and the opposing direction of the pair of sidewalls of the support member (the opposing direction of the pair of main surfaces of the pair of sidewalls) may be open (not shielded).

[0027] The thickness T of at least one portion selected from the group consisting of the sidewall portion and the bottom portion of the support member may be within the following ranges. From the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission, the thickness T may be 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, or 80 μm or more. From the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission, for reasons such as easy heat transfer to the electron emitting member, the thickness T may be 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or less, 120 μm or less, 100 μm or less, 90 μm or less, or 80 μm or less. From these viewpoints, the thickness T may be 10 to 300 μm, 10 to 200 μm, 10 to 100 μm, 30 to 300 μm, 30 to 200 μm, 30 to 100 μm, 50 to 300 μm, 50 to 200 μm, or 50 to 100 μm.

[0028] The electron source according to the present embodiment includes a conductive member between the electron-emitting member and the support member and in contact with the electron-emitting member and the support member. The electron source according to the present embodiment may include a single conductive member or a plurality of conductive members.

[0029] Examples of materials constituting the conductive member (conductive material) include metal materials and carbon materials. Examples of metal materials include transition metals such as titanium, tantalum, zirconium, and tungsten. The conductive member may contain at least one material selected from the group consisting of titanium, tantalum, zirconium, tungsten, and a carbon material, or may contain at least one material selected from the group consisting of titanium and a carbon material, in order to easily obtain sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The conductive member may contain at least one material selected from the group consisting of titanium alone, zirconium boride (e.g., ZrB2), tantalum boride (e.g., TaB2), tungsten boride (e.g., W2B5), tantalum nitride (e.g., TaN), titanium carbide (e.g., TiC), and a carbon material, in order to easily obtain sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The conductive member may contain particles containing a conductive material.

[0030] The conductive member may contain titanium, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The titanium content in the conductive member may be within the following ranges, based on the total amount of the conductive member, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The titanium content may be 30 volume % or more, 40 volume % or more, 50 volume % or more, 60 volume % or more, or 70 volume % or more. The titanium content may be 90 volume % or less, 85 volume % or less, or 80 volume % or less. From these viewpoints, the titanium content may be 30 to 90 volume %, 30 to 85 volume %, 30 to 80 volume %, 50 to 90 volume %, 50 to 85 volume %, 50 to 80 volume %, 70 to 90 volume %, 70 to 85 volume %, or 70 to 80 volume %.

[0031] The conductive member may contain a carbon material from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The content of the carbon material in the conductive member may be within the following ranges based on the total amount of the conductive member from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The content of the carbon material may be 10% by volume or more, 15% by volume or more, or 20% by volume or more. The content of the carbon material may be 70% by volume or less, 60% by volume or less, 50% by volume or less, 40% by volume or less, or 30% by volume or less. From these viewpoints, the content of the carbon material may be 10 to 70% by volume, 15 to 70% by volume, 20 to 70% by volume, 10 to 50% by volume, 15 to 50% by volume, 20 to 50% by volume, 10 to 30% by volume, 15 to 30% by volume, or 20 to 30% by volume.

[0032] The conductive member may contain titanium and a carbon material from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The content of the carbon material in the conductive member may be in the following ranges per 100 parts by volume of titanium from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission. The content of the carbon material may be 10 parts by volume or more, 20 parts by volume or more, or 30 parts by volume or more. The content of the carbon material may be 200 parts by volume or less, 150 parts by volume or less, 100 parts by volume or less, 80 parts by volume or less, 50 parts by volume or less, 40 parts by volume or less, or 30 parts by volume or less. From these viewpoints, the content of the carbon material may be 10 to 200 parts by volume, 10 to 100 parts by volume, 10 to 50 parts by volume, 20 to 200 parts by volume, 20 to 100 parts by volume, 20 to 50 parts by volume, 30 to 200 parts by volume, 30 to 100 parts by volume, or 30 to 50 parts by volume.

[0033] The thickness of the conductive member between the electron-emitting member and the support member may be within the following ranges: The thickness of the conductive member may be 1 μm or more, 3 μm or more, 5 μm or more, 8 μm or more, 10 μm or more, 12 μm or more, or 15 μm or more, from the viewpoint of easily stabilizing the bond between the electron-emitting member and the support member and thus easily obtaining sufficient electron emission characteristics even after a certain time has passed since electron emission began. The thickness of the conductive member may be 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since electron emission began, for reasons such as easily conducting sufficient heat to the electron-emitting member. From these viewpoints, the thickness of the conductive member may be 1 to 50 μm, 1 to 30 μm, 1 to 20 μm, 5 to 50 μm, 5 to 30 μm, 5 to 20 μm, 10 to 50 μm, 10 to 30 μm, or 10 to 20 μm.

[0034] At least a portion of the conductive member may be disposed in the internal space of the support member. The conductive member may have a pair of sidewalls extending in the electron emission direction and a bottom extending in a direction perpendicular to the electron emission direction. The pair of sidewalls may be parallel and opposed to each other. Base ends of each of the pair of sidewalls in the electron emission direction may be connected to the bottom. Both ends of the conductive member in a direction perpendicular to the electron emission direction and the opposing direction of the pair of sidewalls of the conductive member may be open (not shielded).

[0035] The conductive member may be in contact with a side surface of the electron emitting member or may be in contact with a base end of the electron emitting member. The sidewall portion of the conductive member may be in contact with the electron emitting member or may be in contact with a side surface of the electron emitting member. The bottom portion of the conductive member may be in contact with the electron emitting member or may be in contact with a base end of the electron emitting member. The conductive member may be in contact with a wall portion that defines an internal space in the support member or may be in contact with a sidewall portion of the support member. The sidewall portion of the conductive member may be in contact with the support member or may be in contact with a wall portion that defines an internal space in the support member or may be in contact with a sidewall portion of the support member. The bottom portion of the conductive member may not be in contact with the support member or the bottom of the support member, and may be separated from the bottom portion of the support member, from the viewpoint of easily releasing strain stress associated with expansion of the electron emitting member and thus easily suppressing the occurrence of cracks. The bottom portion of the conductive member may be in contact with the bottom portion of the support member, from the viewpoint of easily obtaining a strong bond between the support member and the conductive member.

[0036] In the electron source according to this embodiment, from the viewpoint of easily obtaining sufficient electron emission characteristics even after a certain time has passed since the start of electron emission, the support member may have an internal space that accommodates at least a portion of the electron emission member (for example, the base end portion of the electron emission member), and the conductive member may be in contact with the electron emission member and the support member in the internal space.

[0037] The electron source according to this embodiment may include a pair of filaments connected to a support member. The filaments may be connected to a sidewall of the support member, or, if the support member has an internal space, may be connected to an outer surface of a wall defining the internal space of the support member (the surface opposite to the inner surface facing the internal space). One end of the filament may be connected to the support member, and the other end of the filament may be supported by a base or the like.

[0038] Examples of materials for the filament include tungsten, rhenium, molybdenum, platinum, aluminum, silicon, potassium, etc. The filament may be a tungsten filament (a filament containing tungsten).

[0039] The electron source according to this embodiment may include a covering member that covers at least a portion of the assembly of the electron-emitting member, the support member, and the conductive member. The electron source according to this embodiment may include a single covering member, or may include a plurality of covering members. The covering member may cover at least a portion of the electron-emitting member, may cover at least a portion of the support member, or may cover at least a portion of the conductive member. The covering member may cover a connection portion between the support member and the filament. The shape of the covering member is not particularly limited.

[0040] Examples of the constituent material of the covering member include conductive materials such as metal materials and carbon materials. Examples of the metal materials include transition metals such as titanium, tantalum, zirconium, and tungsten. The covering member may contain a transition metal or tantalum, from the viewpoint of easily achieving good thermal conduction.

[0041] 1 and 2 are drawings showing an example of an electron source, where Fig. 1 is a plan view showing the example of the electron source and Fig. 2 is an end view taken along line II-II in Fig. 1. The electron source 100 in Fig. 1 and Fig. 2 includes an electron emitting member 10, a supporting member 20, a conductive member 30, a pair of filaments 40a, 40b, and a covering member 50.

[0042] The electron emitting member 10 is a long, columnar member having a tip 10a that emits electrons (electron beams) and a base end 10b opposite the tip 10a. The tip 10a of the electron emitting member 10 is tapered to a sharp point. The tip 10a of the electron emitting member 10 is located at the center of a cross section perpendicular to the electron emission direction of the electron emitting member 10 (axial direction of the electron emitting member: longitudinal direction of the electron emitting member 10). The cross section perpendicular to the electron emission direction of the electron emitting member 10 has a rectangular shape. The electron emitting member 10 has main surfaces 10c and 10d that form the long sides of the cross section perpendicular to the electron emission direction of the electron emitting member 10. The main surfaces 10c and 10d are parallel and face each other.

[0043] The support member 20 supports the electron emitter 10 via a conductive member 30. The support member 20 has rectangular plate-shaped sidewall portions 22, 24 extending in the electron emission direction and a rectangular plate-shaped bottom portion 26 extending in a direction perpendicular to the electron emission direction. The sidewall portions 22, 24 face each other in parallel and have main surfaces 22a, 24a facing each other in parallel. The base ends of the sidewall portions 22, 24 in the electron emission direction are connected to the bottom portion 26. The support member 20 has an internal space S defined by the sidewall portions 22, 24 and the bottom portion 26. A portion of the electron emitter 10 on the base end 10b side is accommodated in the internal space S. Both ends of the support member 20 in a direction perpendicular to the electron emission direction and the opposing direction of the sidewall portions 22, 24 (the opposing direction of the main surfaces 22a, 24a) are open.

[0044] The conductive member 30 (the entire conductive member 30) is disposed in the internal space S of the support member 20. The conductive member 30 has rectangular plate-shaped sidewall portions 32, 34 extending in the electron emission direction and a rectangular plate-shaped bottom portion 36 extending in a direction perpendicular to the electron emission direction. The sidewall portions 32, 34 face each other in parallel. The sidewall portions 32, 34 contact the main surfaces 10c, 10d of the electron emitter 10 and the main surfaces 22a, 24a of the support member 20 between the electron emitter 10 and the support member 20. The base ends of the sidewall portions 32, 34 in the electron emission direction are connected to the bottom portion 36. The bottom portion 36 contacts the base end of the electron emitter 10 and is spaced apart from the bottom portion 26 of the support member 20. Both ends of the conductive member 30 in the direction perpendicular to the electron emission direction and the opposing direction of the sidewall portions 32, 34 are open.

[0045] One end of the filament 40a is connected to the surface of the side wall 22 of the support member 20 opposite to the main surface 22a. One end of the filament 40b is connected to the surface of the side wall 24 of the support member 20 opposite to the main surface 24a.

[0046] The covering member 50 covers the entire support member 20 and fills the space between the base end 10b of the electron emitting member 10 and the bottom 26 of the support member 20. As a result, the covering member 50 covers the portion of the electron emitting member 10 on the base end 10b side, the entire conductive member 30, the connection portion between the support member 20 and one end of the filaments 40a, 40b, etc.

[0047] The method for manufacturing an electron source according to this embodiment is a method for manufacturing the above-described electron source (the electron source according to this embodiment). In the method for manufacturing an electron source according to this embodiment, an electron emitting member (an electron emitting member containing iridium and lanthanoid) and a supporting member are joined via a conductive member. That is, the method for manufacturing an electron source according to this embodiment includes a joining step of joining the electron emitting member and the supporting member via the conductive member. In the joining step, a joined body of the electron emitting member, the supporting member, and the conductive member can be obtained.

[0048] A first embodiment of the bonding step may be a step of bringing the support member and the conductive member into contact with each other while the conductive member is in contact with the electron emitting member. A second embodiment of the bonding step may be a step of bringing the electron emitting member and the conductive member into contact with each other while the conductive member is in contact with the support member. A third embodiment of the bonding step may be a step of bringing the electron emitting member and the support member into contact with the conductive member simultaneously. In the bonding step, the support member and the conductive member may be brought into contact with each other in the internal space of the support member while the conductive member is in contact with the electron emitting member (e.g., the base end portion of a long electron emitting member), or the electron emitting member (e.g., the base end portion of a long electron emitting member) may be brought into contact with the conductive member in the internal space while the conductive member is in contact with the support member in the internal space of the support member. In the bonding step, the electron emitting member and the support member may be bonded via the conductive member to obtain a bonded body of the electron emitting member, the support member, and the conductive member, and then the bonded body may be heated in a vacuum atmosphere. The heating temperature may be, for example, 1300 to 1600°C.

[0049] The method for manufacturing an electron source according to this embodiment may include, before the bonding step, a step of bringing the electron-emitting member and the conductive member into contact with each other, or a step of bringing the support member and the conductive member into contact with each other. The method for bringing the conductive member into contact with the electron-emitting member or the support member is not particularly limited, and examples thereof include dipping.

[0050] The method for manufacturing an electron source according to this embodiment may include, before the bonding step, an electron-emitting member fabrication step of processing a member containing iridium and lanthanoid to obtain an electron-emitting member. In the electron-emitting member fabrication step, a columnar member may be obtained from the member containing iridium and lanthanoid, and then one end of the columnar member may be sharpened. In the electron-emitting member fabrication step, at least a part of the side surface of the columnar member may be polished (smoothed) after the columnar member is obtained from the member containing iridium and lanthanoid.

[0051] The method for manufacturing the electron source according to this embodiment may include a filament connecting step of connecting the filament to the support member after the bonding step. The filament may be connected to the support member by welding or the like.

[0052] The method for manufacturing an electron source according to this embodiment may include, after the bonding step, a covering member forming step of forming a covering member that covers at least a part of an assembly of an electron emitting member, a supporting member, and a conductive member. In the covering member forming step, after the filament connecting step, the covering member may cover the connection portion between the supporting member and the filament. The method for manufacturing an electron source according to this embodiment may include a plurality of covering member forming steps, and the covering portion of the assembly, the constituent material of the covering member, etc. may be different for each step. In the covering member forming step, the assembly may be heated in a vacuum atmosphere after the covering member is brought into contact with at least a part of the assembly. The heating temperature may be, for example, 1350 to 1550°C. [Example]

[0053] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples.

[0054] (Fabrication of electron source) [Example 1] The electron source 100 shown in FIGS. 1 and 2 was fabricated according to the following procedure.

[0055] A columnar member (a square column measuring 500 μm in length, 400 μm in width, and 1300 μm in length) was cut from an IrCe ingot. One end of this columnar member was machined into a cone shape with a tip angle of 45°, a base radius of 200 μm, and a height of 200 μm. Then, the main surfaces 10c and 10d (surfaces in contact with the conductive member 30) constituting the long sides of the columnar member in a cross section perpendicular to the electron emission direction (the longitudinal direction of the columnar member) were polished and smoothed to obtain the electron emitting member 10. The tip of the electron emitting member 10 (the apex of the cone) was located at the center of the cross section of the electron emitting member 10 perpendicular to the electron emission direction. The surface roughness Ra of the main surfaces 10c and 10d (surfaces in contact with the conductive member 30) of the electron emitting member 10 was 0.02 μm, and the surface roughness Ra of the main surface (surface not in contact with the conductive member 30) constituting the short side in a cross section perpendicular to the electron emission direction of the electron emitting member 10 was 0.45 μm. The surface roughness Ra was obtained based on 3D data obtained by observing the main surfaces with an objective lens (magnification: 150x) using a laser microscope (manufactured by Keyence Corporation, product name: VK-X1000).

[0056] A support member 20 having an internal space S (length 500 μm×width 400 μm×height 500 μm) defined by sidewall portions 22, 24 and a bottom portion 26 was obtained by bending a tantalum plate having a thickness of 80 μm.

[0057] A paste for obtaining the conductive member 30 was obtained by mixing titanium powder (elemental titanium) and colloidal carbon, followed by the addition of water. The amount of colloidal carbon (solid content) used was 30 parts by volume relative to 100 parts by volume of titanium powder. Next, the base end portion of the above-mentioned electron emitting member 10 (length in the electron emission direction: 500 μm) was immersed in this paste to obtain a coating film on the surface of the electron emitting member 10. Subsequently, the base end portion of the electron emitting member 10 (portion on which the coating film was formed) was placed in the internal space S of the support member 20, and then the coating film on both ends of the support member 20 in the direction perpendicular to the electron emission direction and the opposing direction of the side wall portions 22, 24 (opposing direction of the main surfaces 22a, 24a) was scraped off with a needle to obtain a structure A. Then, this structure A was placed in a vacuum atmosphere (vacuum degree: 1×10 -6By heating at 1400° C. and 2000 Pa for 2 minutes, a structure B including a conductive member 30 in contact with the electron emitting member 10 was obtained.

[0058] One end of each of filaments 40a and 40b (material: tungsten, diameter: 150 μm) was welded to the outer surfaces (surfaces opposite to the main surfaces 22a and 24a) of the sidewalls 22 and 24 of the support member 20 of the structure B.

[0059] Next, tantalum powder (elemental tantalum) was supplied so as to cover both ends of the support member 20 in the direction perpendicular to the electron emission direction and the opposing direction of the sidewall portions 22, 24 (opposing direction of the main surfaces 22a, 24a), and then tantalum powder (elemental tantalum) was supplied so as to cover both ends of the support member 20 in the opposing direction of the main surfaces 22a, 24a (including the welded portions between the support member 20 and the filaments 40a, 40b), thereby obtaining a structure C. This structure C was placed in a vacuum atmosphere (vacuum degree: 1×10 -6 The coating member 50 was formed by heating at 1500° C. for 60 minutes at a temperature of 1000 Pa, and the electron source 100 was obtained.

[0060] A cross-section specimen preparation device (manufactured by JEOL Ltd., product name: Cross Section Polisher) was used to expose a cross section of the joint between the electron emitting member 10, the support member 20, and the conductive member 30 in the electron source 100. Then, this cross section was observed using a scanning electron microscope (SEM-EDS), and the thickness of one point of the conductive member 30 between the electron emitting member 10 and the support member 20 was measured. The thickness of the conductive member 30 was 15 μm.

[0061] [Comparative Example 1] In the production of the electron source, a columnar member (a square column of 400 μm length × 500 μm width × 1300 μm length, the longitudinal direction of the columnar member: LaB6 <100> The electron source 100 was fabricated in the same manner as in Example 1, except that the crystal orientation was changed.

[0062] (Evaluation of electron emission characteristics) 3 is a schematic diagram showing an example of an electron beam apparatus (apparatus for evaluating electron emission characteristics) equipped with an electron source. The electron emission characteristics (current density) of the above-described electron source 100 were evaluated in the electron beam apparatus 200 of FIG. 3 by the following procedure.

[0063] The electron beam device 200 of FIG. 3 includes a suppressor electrode 210, an extraction electrode 220, and a fluorescent screen 230, each having a circular opening, and a cylindrical electrode 240 having a circular opening end. The suppressor electrode 210, the extraction electrode 220, and the fluorescent screen 230 are arranged parallel to one another in this order, with the cylindrical electrode 240 being arranged on the opposite side of the fluorescent screen 230 from the suppressor electrode 210 and the extraction electrode 220. The centers of the openings of the suppressor electrode 210, the extraction electrode 220, and the fluorescent screen 230, and the center of the opening end of the cylindrical electrode 240, are coaxially positioned. The distance between the suppressor electrode 210 and the extraction electrode 220 is 0.3 mm, and the distance between the extraction electrode 220 and the fluorescent screen 230 is 60 mm. The diameter of the opening of the suppressor electrode 210 is 0.8 mm, and the diameter of the opening of the extraction electrode 220 is 0.5 mm.

[0064] The electron source 100 was arranged so that the tip of the electron emitting member 10 in the above-described electron source 100 was located on the opposite side of the suppressor electrode 210 from the extraction electrode 220. The tip 10a of the electron emitting member 10 was adjusted so as to be located coaxially with the centers of the openings of the suppressor electrode 210, the extraction electrode 220, and the fluorescent screen 230, and with the center of the opening end of the cylindrical electrode 240. The distance between the center of the opening of the suppressor electrode 210 and the tip of the electron emitting member 10 was 150 μm.

[0065] A power supply (heating power supply) 250a was connected to the other ends (ends opposite to the ends of the electron source 100 welded to the support member 20) of the filaments 40a and 40b of the electron source 100, and a power supply 250b for applying a bias voltage to the electron emitting member 10 was connected to the electron source 100 and the suppressor electrode 210. A power supply 250c for applying an emitter voltage to the electron emitting member 10 was connected to the power supplies 250a and 250b.

[0066] An ammeter 260a that measures the total emission current from the electron source 100 was connected between the power supply 250c and the ground. The extraction electrode 220, the fluorescent screen 230, and the cylindrical electrode 240 were connected to the ground. An ammeter 260b that can measure the current that reaches the fluorescent screen 230 was connected between the fluorescent screen 230 and the ground. An ammeter 260c that can measure the current that reaches the cylindrical electrode 240 was connected between the cylindrical electrode 240 and the ground.

[0067] While the electron emitting member 10 of the electron source 100 is maintained at 1530° C., a vacuum atmosphere (vacuum degree: 1×10 -6 Electrons E were emitted from the tip of the electron-emitting member 10 at a pressure of 1000 Pa and an acceleration voltage of 1800 V. The current density was measured 12 hours after the start of electron emission. The current density was calculated by dividing the total emission current (unit: A) measured by the ammeter 260a by the opening area of ​​the suppressor electrode 210. The opening area of ​​the suppressor electrode 210 was calculated by (diameter of the suppressor electrode 210 opening (unit: cm) / 2) 2 × π". The current density of Example 1 (Ir2Ce) was 1.4 A / cm 2 and the current density of Comparative Example 1 (LaB6) was 0.3 A / cm 2 It was. [Explanation of symbols]

[0068] 10...electron emitting member, 10a...tip, 10b...base, 10c, 10d, 22a, 24a...main surface, 20...support member, 22, 24, 32, 34...side wall portion, 26, 36...bottom, 30...conductive member, 40a, 40b...filament, 50...covering member, 100...electron source, 200...electron beam device, 210...suppressor electrode, 220...extraction electrode, 230...fluorescent screen, 240...cylindrical electrode, 250a, 250b, 250c...power source, 260a, 260b, 260c...ammeter, E...electrons, S...internal space.

Claims

1. an electron-emitting member containing iridium and a lanthanoid; a conductive support member that supports the electron-emitting member; a conductive member in contact with the electron-emitting member and the support member between the electron-emitting member and the support member.

2. 2. The electron source according to claim 1, wherein the lanthanoid comprises at least one selected from the group consisting of lanthanum and cerium.

3. 2. The electron source according to claim 1, wherein the molar ratio of said iridium to said lanthanoid in said electron-emitting member is 1.0 or more.

4. 2. The electron source according to claim 1, wherein the molar ratio of said iridium to said lanthanoid in said electron-emitting member is 2.0 or more.

5. 2. The electron source according to claim 1, wherein said electron-emitting member has a surface having a surface roughness Ra of 0.10 [mu]m or less as a contact surface with said conductive member.

6. 2. The electron source according to claim 1, wherein the support member contains at least one selected from the group consisting of tantalum, tungsten, rhenium, and molybdenum.

7. 2. The electron source according to claim 1, wherein the support member has an internal space that accommodates at least a portion of the electron-emitting member, and the conductive member contacts the electron-emitting member and the support member in the internal space.

8. 2. The electron source according to claim 1, wherein the conductive member has a thickness of 1 to 50 μm.

9. 2. The electron source of claim 1, wherein the conductive member comprises titanium.

10. 10. The electron source according to claim 9, wherein the content of titanium in said conductive member is 50 to 90% by volume based on the total volume of said conductive member.

11. A method for manufacturing an electron source according to any one of claims 1 to 10, comprising: The electron-emitting member and the supporting member are joined together via the conductive member.

12. An electron beam device comprising the electron source according to any one of claims 1 to 10.

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