Electron source and method for manufacturing the same, emitter, and device including the emitter

Abstract

The electron source according to the present disclosure includes: a columnar portion made of a first material having electron emission characteristics; and a cylindrical portion made of a second material having a work function larger than that of the first material, the cylindrical portion being arranged so as to surround the columnar portion, wherein a hole extending in a direction from one end face to the other end face and having a substantially circular cross-sectional shape is formed in the cylindrical portion, the columnar portion has a substantially triangular or substantially quadrilateral cross-sectional shape, and is fixed to the cylindrical portion in a state of abutting against the inner surface of the hole.

Description

Technical Field

[0001] The present disclosure relates to an electron source and a method for manufacturing the same, a transmitter, and a device including the transmitter. Background Art

[0002] A transmitter including an electron source is used, for example, in an electron microscope and a semiconductor inspection device. The transmitter disclosed in Patent Document 1 includes a first member having electron emission characteristics and a second member covering the first member, and a groove having a specified size is provided between the first member and the second member. The electron gun disclosed in Patent Document 2 includes an electron gun cathode and a holder for holding the electron gun cathode. The electron gun cathode has a quadrangular flat surface at its front end, and the front end portion is exposed and protrudes from the holder (see Figure 6 ) of Patent Document 2.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-69364

[0006] Patent Document 2: Japanese Patent No. 5525104 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] An electron source is extremely delicate. In paragraph

[0055] of Patent Document 2, the size of the electron gun cathode is described as 50 μm × 50 μm × 100 μm. In order to manufacture such an electron source (electron gun) formed of delicate components, skilled techniques are required.

[0009] The present disclosure provides a method for manufacturing an electron source useful for efficiently manufacturing a delicate electron source. In addition, the present disclosure provides an electron source that can sufficiently suppress the detachment of a member that emits electrons from a member that holds the member, and a transmitter including the electron source. Further, the present disclosure provides a device including the above-described transmitter.

[0010] Means for Solving the Problems

[0011] One aspect of the present disclosure relates to a method of manufacturing an electron source, which includes the following steps: Step (A) of preparing a plurality of first members, each of the plurality of first members having a columnar portion made of a first material with electron emission characteristics; Step (B) of preparing a plurality of second members, each of the second members having a work function greater than that of the first material and each formed with a hole extending in a direction from one end face to the other end face; Step (C) of selecting one first member from the plurality of first members and one second member from the plurality of second members; and Step (D) of pressing the columnar portion of the selected first member into the hole of the selected second member, wherein the columnar portions of the plurality of first members each have a substantially quadrilateral cross-sectional shape, the holes of the plurality of second members each have a substantially circular cross-sectional shape, in Step (C), a set of a first member and a second member that satisfy the following conditions are selected from the plurality of first members and the plurality of second members, and in Step (D), by pressing the columnar portion into the hole of the second member, a state is formed in which a part of the side surface of the columnar portion abuts against the inner surface of the hole of the second member, whereby the columnar portion is fixed to the second member.

[0012] <Condition>

[0013] L 1 / R 1 >1…(1)

[0014] In the inequality (1), L 1 represents the length of the longer diagonal among the two diagonals of the substantially quadrilateral shape, and R 1 represents the diameter of the hole.

[0015] According to the above manufacturing method, in Step (C), a first member and a second member with matching dimensions are selected from the plurality of members and Step (D) is carried out using them. Thus, as described above, a state is formed in which a part of the side surface of the columnar portion abuts against the inner surface of the hole of the second member, whereby the columnar portion can be fixed to the second member. Therefore, when manufacturing an electron source, the loss of components can be sufficiently reduced. That is, manufacturing defects caused by the mismatch in dimensions between the columnar portion and the hole can be sufficiently reduced. As such defects, for example, there can be cited: the columnar portion of the first member not entering the hole of the second member; the columnar portion falling off from the hole because it does not abut against the inner surface of the hole; and so on.

[0016] The cross-sectional shape of the columnar portion of the first member is not limited to a substantially quadrilateral shape and can also be a substantially triangular shape. In this case, in the above Step (C), a set of a first member and a second member that satisfy the following conditions can be selected from the plurality of first members and the plurality of second members.

[0017] <Condition>

[0018] The diameter R of the circumscribed circle of the substantially triangular shape2 The diameter R of the pore 1 is larger and when a substantially triangular shape is arranged in a circle having the same diameter as the diameter R of the pore 1 at least two angles of the substantially triangular shape are in contact with the circle.

[0019] An electron source according to one aspect of the present disclosure includes: a columnar portion made of a first material having electron emission characteristics; and a cylindrical portion made of a second material having a work function larger than that of the first material, the cylindrical portion being arranged so as to surround the columnar portion, wherein a pore having a substantially circular cross-sectional shape and extending in a direction from one end face to the other end face is formed in the cylindrical portion, the columnar portion has a substantially triangular or substantially quadrilateral cross-sectional shape, and is fixed to the cylindrical portion in a state of being in contact with the inner surface of the pore.

[0020] According to the above-described electron source, it is possible to sufficiently suppress the detachment of the member (columnar portion) that emits electrons from the member (cylindrical portion) that holds it. At the front end portion of the electron source, it is preferable that a flat surface is formed by the electron emission surface of the columnar portion and the end face of the cylindrical portion. By forming such a flat surface, it is possible to sufficiently suppress the emission of electrons to the side.

[0021] A transmitter according to one aspect of the present disclosure includes the above-described electron source. A device according to one aspect of the present disclosure includes the above-described transmitter. As a device including the transmitter, for example, an electron microscope, a semiconductor manufacturing device, and an inspection device can be cited.

[0022] Advantageous Effects of the Invention

[0023] According to the present disclosure, a method for manufacturing an electron source useful for efficiently manufacturing a fine electron source can be provided. In addition, according to the present disclosure, an electron source capable of sufficiently suppressing the detachment of the member that emits electrons from the member that holds it and a transmitter including the same can be provided. Further, according to the present disclosure, a device including the above-described transmitter can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Figure 1 is a cross-sectional view schematically showing an embodiment of the electron source according to the present disclosure.

[0025] Figure 2 Figure 2 is a top view showing the configuration of the front end of the electron source Figure 1 shown.

[0026] Figure 3 Figure 3 In (a) of Figure 3 is a cross-sectional view schematically showing a first member including a columnar portion, Figure 3 ​​​​​​Top view of the front end portion of the first member shown in (a) of Figure 3 (c) is a cross-sectional view schematically showing the second member formed with holes.

[0027] Figure 4 Figure 4 (a) to Figure 4 (c) are cross-sectional views schematically showing the process of manufacturing Figure 1 the electron source shown in

[0028] Figure 5 Figure 5 is a top view showing the size relationship between the columnar portion (cross-sectional shape: substantially square) of the first member and the holes of the second member.

[0029] Figure 6 Figure 6 is a cross-sectional view schematically showing an embodiment of the emitter related to the present disclosure.

[0030] Figure 7 Figure 7 is a top view showing the size relationship between the columnar portion (cross-sectional shape: substantially triangular) of the first member and the holes of the second member.

[0031] Figure 8 Figure 8 (a) is a cross-sectional view schematically showing another embodiment of the electron source related to the present disclosure, Figure 8 (b) is Figure 8 an enlarged cross-sectional view taken along line b-b of (a) of Figure 8 (c) is Figure 8 an enlarged cross-sectional view taken along line c-c of (a) of Detailed Embodiments

[0032] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same reference numerals are used for the same elements or elements having the same function, and repeated descriptions are omitted. It should be noted that the present invention is not limited to the following embodiments.

[0033] <Electron Source>

[0034] Figure 1 is a cross-sectional view schematically showing the electron source according to this embodiment. Figure 2 is for showing Figure 1 ​​​​​​​​​​A plan view of the configuration of the front end of the electron source 10 shown. The electron source 10 includes a columnar portion 1 and an electron emission restricting member 2 disposed so as to surround the columnar portion 1. The columnar portion 1 is made of a first material (electron emission material) having electron emission characteristics. The end face 1a of the columnar portion 1 is an electron emission surface, and the normal thereto is the electron emission direction. On the other hand, the electron emission restricting member 2 is made of a second material (electron emission restricting material) having a work function greater than that of the first material. The electron emission restricting member 2 has a cylindrical portion 2a formed with a hole 3 and a base end portion 2b not formed with the hole 3. The base end portion 2b forms the bottom 3a of the hole 3. The hole 3 extends in the direction from the end face 2c to the other end face 2d of the electron emission restricting member 2. In the present embodiment, the opening area of the hole 3 is constant from the end face 2c toward the end face 2d.

[0035] As Figure 2 shown, the columnar portion 1 has a cross-sectional shape that is not similar to the cross-sectional shape of the hole 3 of the electron emission restricting member 2 and is fixed to the electron emission restricting member 2 in a state of abutting against the inner surface of the hole 3. In the present embodiment, in a cross-section orthogonal to the length direction of the columnar portion 1, the shape of the columnar portion 1 is substantially square, and the shape of the hole 3 is substantially circular. In the present embodiment, it is assumed that the strength of the columnar portion 1 is higher than the strength of the cylindrical portion 2a, and the columnar portion 1 is fixed in a state where a part of the side surface of the columnar portion 1 is embedded in the cylindrical portion 2a. According to the electron source 10, it is possible to sufficiently suppress the columnar portion 1 from coming off the electron emission restricting member 2. It should be noted that when the strength of the columnar portion 1 is lower than the strength of the cylindrical portion 2a, the corner portion of the first member 11 is scraped to have a roundness, and the corner portion abuts against the inner surface of the hole 13 to fix the columnar portion 1 to the electron emission restricting member 2.

[0036] In the front end face of the electron source 10, a flat surface is formed by the end face 1a (electron emission surface) of the columnar portion 1 and the end face 2c of the electron emission restricting member 2. In addition, the entire side surface of the columnar portion 1 is covered by the cylindrical portion 2a. As described above, by not allowing the columnar portion 1 to protrude from the cylindrical portion 2a, the emission of unnecessary electrons, that is, the lateral emission of electrons, can be sufficiently suppressed. For example, in order to obtain electrons with a larger current, the front end portion of the electron source 10 is heated to a high temperature of about 1550 °C and a high electric field of several kV is applied to the electron source 10. When such a high electric field is applied, redundant electrons are also generated from parts other than the front end portion of the electron source. These redundant electrons may reduce the brightness of the electron beam from the front end portion due to the space charge effect or cause unnecessary heating of the surrounding electrode components. To prevent the above situation, only the electron emission portion (end face 1a of the columnar portion 1) of the electron source 10 is exposed, and the other surfaces are covered by the cylindrical portion 2a, thereby obtaining only a high-brightness electron beam from the front end portion. It should be noted that the so-called "flat surface" here means that the step difference between the end face 1a and the end face 2c is less than 2 μm. As long as this step difference is less than 2 μm, the columnar portion 1 may protrude from the cylindrical portion 2a, and the end face 1a may also be recessed with respect to the end face 2c. This step difference may also be less than 1.5 μm or less than 1.0 μm.

[0037] By covering the entire side surface of the columnar portion 1 with the cylindrical portion 2a, an effect of suppressing the occurrence of a phenomenon called microdischarge can also be achieved. That is, in thermionic emission, electrons are emitted by heating the electron source to a high temperature. Along with this, when the electron emission material evaporates, it adheres to the surrounding electrode components and forms fibrous crystals called whiskers. If charges accumulate in these whiskers, microdischarge will occur. Microdischarge becomes an important factor that makes the electron beam unstable and degrades the device performance. By covering the entire side surface of the columnar portion 1 with the cylindrical portion 2a, the sublimated electron emission material is trapped by the cylindrical portion 2a, and the amount of adhesion to the surrounding electrode components can be reduced, so that microdischarge is not likely to occur. It should be noted that the cylindrical portion 2a covers the entire side surface of the columnar portion 1 and does not have a notch at a part of the circumferential direction. Since the cylindrical portion 2a does not have a notch, the lateral emission of electrons can be sufficiently suppressed.

[0038] (Electron emission material)

[0039] The columnar portion 1 is made of an electron emission material (first material). The electron emission material is a material that emits electrons by heating. The work function of the electron emission material is smaller than that of the electron emission restricting material, and the strength is higher than that of the electron emission restricting material. As an example of the electron emission material, lanthanum boride (LaB 6 ) and cerium boride (CeB 6) rare earth borides such as these; high melting point metals such as tungsten, tantalum, and hafnium, as well as their oxides, carbides, and nitrides; noble metal-rare earth alloys such as iridium-cerium. The work functions of these materials are as described below.

[0040] · Lanthanum boride (LaB 6 ): 2.8 eV

[0041] · Cerium boride (CeB 6 ): 2.8 eV

[0042] · Tantalum carbide: 3.2 eV

[0043] · Hafnium carbide: 3.3 eV

[0044] From the viewpoints of electron emission characteristics, strength, and processability, the electron emission material constituting the columnar portion 1 is preferably a rare earth boride. When the columnar portion 1 is formed of a rare earth boride, the columnar portion 1 is preferably a single crystal processed so that the work function is low and the <100> orientation, which easily emits electrons, is aligned with the electron emission direction. The columnar portion 1 can be formed into a desired shape by electrical discharge machining or the like. The side surface of the columnar portion 1 is considered to have a slow evaporation rate, so the (100) plane crystal face is preferred.

[0045] In the present embodiment, the shape of the columnar portion 1 is a quadrangular prism (see Figure 1 , 2 ). The length of the columnar portion 1 is preferably 0.1 to 1 mm, more preferably 0.2 to 0.6 mm, and further preferably about 0.3 mm. By making the length 0.1 mm or more, the operation tends to become easier, and by making the length 1 mm or less, the introduction of cracks or the like tends to be less likely. The cross-sectional shape of the columnar portion 1 is substantially square. The side length is preferably 20 to 300 μm, more preferably 50 to 150 μm, and further preferably about 100 μm.

[0046] (Electron emission restricting material)

[0047] The electron emission restricting member 2 is made of an electron emission restricting material. The work function of the electron emission restricting material is greater than that of the electron emission material. By covering the side surface of the columnar portion 1 with the electron emission restricting member 2, electron emission from the side surface of the columnar portion 1 can be suppressed.

[0048] The work function W of the electron emission restricting member 2 2 and the work function W of the columnar portion 1 1 difference (ΔW = W 2 - W 1 ) is preferably 0.5 eV or more, more preferably 1.0 eV or more, and further preferably 1.6 eV or more.

[0049] The electron emission limiting material preferably contains a high melting point metal or its carbide, and preferably contains at least one or more selected from tantalum metal, titanium metal, zirconium metal, tungsten metal, molybdenum metal, rhenium metal, tantalum carbide, titanium carbide, and zirconium carbide. In addition, the electron emission limiting material may contain at least one or more of boron carbide and graphite (carbon material). In addition, the electron emission limiting material may also contain at least one or more of niobium, hafnium, and vanadium. As the electron emission limiting material, glassy carbon (for example, Glassy Carbon (trade name, manufactured by REIHO Co., Ltd.)) can also be used. The work functions of these materials are as described below.

[0050] · Rhenium metal: 4.9 eV

[0051] · Boron carbide: 5.2 eV

[0052] · Graphite: 5.0 eV

[0053] In the present embodiment, as described above, the strength of the electron emission limiting material is lower than the strength of the electron emission material. The strength of the two materials can be evaluated using, for example, Vickers hardness. From the viewpoint of having appropriate strength and workability, the Vickers hardness of the material constituting the electron emission limiting member 2 is preferably about 100 HV to 1900 HV. For example, glassy carbon (Vickers hardness: about 230 HV) is suitable as the electron emission limiting material in terms of having appropriate strength. The front end portion 2e (a part of the cylindrical portion 2a) of the electron emission limiting member 2 is processed into a conical shape, and the remaining portion (the remaining portion of the cylindrical portion 2a and the base end portion 2b) is processed into a quadrangular prism shape. By processing the front end portion 2e of the electron emission limiting member 2 into a conical shape, effects such as easily concentrating the electric field and improving the electron emission efficiency can be achieved. It should be noted that a support member (not shown) can be provided around the electron emission limiting member 2.

[0054] The electron emission material and the electron emission limiting material can be appropriately selected and used in combination, for example, from the aspects of their work functions and strengths. Preferred examples of the electron emission material include lanthanum boride (LaB 6 ), cerium boride (CeB 6 ), hafnium carbide, and iridium cerium. Preferred examples of the electron emission limiting material include rhenium metal, boron carbide, and graphite (including glassy carbon). It should be noted that a part of the material that can be used as the electron emission material can also be used as the electron emission limiting material. For example, materials with a work function of about 3.2 to 4.5 eV can be used for both the electron emission material and the electron emission limiting material. Examples of such materials include tungsten metal (work function: 4.5 eV), tantalum metal (work function: 3.2 eV), and hafnium carbide (work function: 3.3 eV).

[0055] <Method of manufacturing electron source>

[0056] Next, a method of manufacturing the electron source 10 will be described. The electron source 10 can be manufactured through the following processes.

[0057] Process (A): Prepare a plurality of columnar first members 11.

[0058] Process (B): Prepare a plurality of second members 12. Each of the plurality of second members 12 has a work function greater than that of the first member 11 and is formed with a hole 13 extending in the direction from one end face 12a to the other end face 12b.

[0059] Process (C): Select one first member 11 from the plurality of first members 11 and select one second member 12 from the plurality of second members 12.

[0060] Process (D): Press the selected first member 11 into the hole 13 of the selected second member 12.

[0061] In the above process (C), a set of first member 11 and second member 12 that satisfy the following conditions are selected from the plurality of first members 11 and the plurality of second members 12. In the above process (D), by pressing the selected first member 11 into the hole 13 of the selected second member 12, a state is formed in which a part of the side surface of the first member 11 abuts against the inner surface of the hole 13 of the second member 12, thereby fixing the first member 11 to the second member 12.

[0062] <Condition>

[0063] L 1 / R 1 >1…(1)

[0064] When the strength of the first member 11 is higher than the strength of the second member 12, by pressing the first member 11 into the hole 13 of the second member 12, a part of the side surface of the first member 11 scrapes the inner surface of the hole 13 and is in a state of being embedded in the second member 12, thereby fixing the first member 11 to the second member 12 (see Figure 5 ). On the other hand, when the strength of the first member 11 is lower than the strength of the second member 12, by pressing the first member 11 into the hole 13 of the second member 12, the corner of the first member 11 is scraped to have a roundness, and the corner abuts against the inner surface of the hole 13 to fix the first member 11 to the second member 12. It should be noted that the strength of the first member 11 and the second member 12 can be evaluated using, for example, Vickers strength.

[0065] Figure 3 of (a) and Figure 3The first member 11 shown in (b) is formed of an electron-emitting material. The first member 11 can be obtained from a block of the electron-emitting material by electrical discharge machining or the like. The first member 11 is a part of the columnar portion 1 that forms the electron source 10.

[0066] Figure 3 The second member 12 shown in (c) is formed of an electron-emission restricting material. The second member 12 can be obtained from a block of the electron-emission restricting material by electrical discharge machining or the like. The hole 13 of the second member 12 is a part of the hole 3 that forms the electron source 10. The opening area of the hole 13 is constant from the end face 12a toward the end face 12b.

[0067] Figure 4 (a) is a cross-sectional view schematically showing a state in which the first member 11 is pressed into the hole 13 of the second member 12. Figure 5 is a top view showing the size relationship between the first member 11 of the first member 11 and the hole 13 of the second member 12. A part of the side surface (four corner portions 11c) of the first member 11 is fitted into the second member 12. It should be noted that in Figure 4 (a), a state in which the first member 11 reaches the deep part of the hole 13 is illustrated, but the first member 11 may not reach the deep part of the hole 13.

[0068] In step (C), the first member 11 and the second member 12 having the hole 13 that satisfy the following conditions are selected.

[0069] <Condition>

[0070] L 1 / R 1 >1…(1)

[0071] In the inequality (1), L 1 represents the length of the diagonal of the cross-section (substantially square) of the first member 11, and R 1 represents the diameter of the hole 13.

[0072] L 1 / R 1 The value of is more preferably satisfies the inequality (1a), further preferably satisfies the inequality (1b), and particularly preferably satisfies the inequality (1c).

[0073] 1 < L 1 / R 1 <1.2…(1a)

[0074] 1 < L 1 / R 1 <1.1…(1b)

[0075] 1 < L 1 / R 1 <1.05…(1c)

[0076] Figure 4 The structure 15A shown in (b) is obtained by cutting out the part surrounded by the dotted rectangle in (a). In the structure 15A, the first member 11 protrudes from the end face 12a. By scraping the protruding portion 11a of the first member 11 with, for example, abrasive paper, the end face 1a (electron emission surface) is formed, and the outer side of the second member 12 is processed into a quadrangular prism shape. Thus, the quadrangular prism 15B shown in (c) can be obtained. By processing one end of the quadrangular prism 15B into a conical shape, the electron source 10 shown in Figure 4 can be obtained. It should be noted that the processing order is not limited to this. For example, starting from the state shown in (a) of Figure 4 , the protruding portion 11a can be scraped first to form a flat surface, and then the part surrounded by the dotted rectangle in (a) of Figure 1 can be cut out. In addition, the shape of the processed second member 12 is not limited to a quadrangular prism shape. For example, in a substantially cylindrical electron source, it can also be a shape in which only the part held by the heater is processed to be flat (see Figure 4 and Figure 4 ). Figure 6 )

[0077] According to the above manufacturing method, in step (C), the first member 11 and the second member 12 with matching dimensions are selected from a plurality of members, and step (D) is performed using them, thereby being able to sufficiently reduce the loss of these members. That is, it is possible to sufficiently reduce manufacturing defects caused by the mismatch between the dimensions of the first member 11 and the hole 13. As such defects, for example, the following can be cited: the first member 11 does not enter the hole 13; the first member 11 falls off from the hole 13 because it does not abut against the inner surface of the hole 13; and so on.

[0078] According to the above manufacturing method, by passing through the process of scraping the protruding portion 11a of the first member 11, a flat surface is formed at the front end of the electron source 10 by the end face 1a (electron emission surface) of the columnar portion 1 and the end face 2c of the cylindrical portion 2a. By making the columnar portion 1 not protrude from the cylindrical portion 2a, as described above, it is possible to sufficiently suppress the release of unnecessary electrons, that is, the release of electrons to the side, and it is also possible to suppress microdischarge caused by the generation of whiskers.

[0079] <Emitter>

[0080] Figure 6 is a cross-sectional view schematically showing an example of the emitter. Figure 6The illustrated emitter 20 includes: an electron source 10; a carbon heater 16 disposed around the electron source 10; electrode pins 17a, 17b; an insulator 18; and a suppressor 19. The carbon heater 16 is used to heat the electron source 10. The electrode pins 17a, 17b are used to supply power to the carbon heater 16. The suppressor 19 is used to suppress excess current. It should be noted that the configuration may also be such that the electron source 10 is heated by means other than the carbon heater 16.

[0081] Examples of the device including the emitter 20 include an electron microscope, a semiconductor manufacturing device, an inspection device, and a processing device.

[0082] As described above, the embodiments of the present disclosure have been described in detail, but the present invention is not limited to the above embodiments. For example, in the above embodiments, a columnar portion 1 having a substantially square cross-sectional shape is illustrated (see Figure 1 , 2 ), but the cross-sectional shape of the columnar portion 1 may be a substantially quadrilateral other than a substantially square, for example, a substantially rectangle, a substantially rhombus, or a substantially parallelogram.

[0083] When the cross-sectional shape of the first member 11 is a substantially quadrilateral other than a substantially square, the above-mentioned L 1 / R 1 represents the following value.

[0084] L 1 : The length of the longer diagonal among the two diagonals of the substantially quadrilateral

[0085] R 1 : The diameter of the hole 13

[0086] When manufacturing an electron source in which the cross-sectional shape of the columnar portion 1 is a substantially triangle, in step (C), the first member 11 and the hole 13 (second member 12) that satisfy the following conditions are selected.

[0087] <Condition>

[0088] The diameter R of the circumscribed circle of the substantially triangle 2 is larger than the diameter R of the hole and when the substantially triangle is arranged in a circle having the same diameter as the diameter R 1 of the hole 13, at least two angles of the substantially triangle are in contact with the circle. 1 In Figure 7 , the solid-line circle R is a circle with a diameter R 1 , and the dash-dotted circle R T is the circumscribed circle of the substantially triangle T.

[0089] In the above-described embodiment, the case where the opening areas of the holes 3 are constant in the direction of their extension has been illustrated, but the holes of the electron emission restricting member 2 may also have a reduced-diameter portion where the opening area becomes smaller from the end face 2c toward the end face 2d side. Figure 8 The electron source 10A shown in (a) of Figure 8 has the same configuration as the electron source 10 except for the shape of the holes. The hole 4 in the electron source 10A is composed of a hole 4a on the end face 2c side, a hole 4b on the end face 2d side, and a tapered portion 4c (reduced-diameter portion) therebetween. The inner diameter of the hole 4b is smaller than the inner diameter of the hole 4a. In this case, as shown in Figure 8 (b) of Figure 8 , if the columnar portion 1 scrapes the inner surface of the hole 4b and is fully fixed in a state of being embedded in the electron emission restricting member 2, then as shown in Figure 8 (c) of Figure 8 , in the hole 4a, the columnar portion 1 may not be in a state of being embedded in the electron emission restricting member 2. It should be noted that here, the tapered portion 4c where the inner diameter continuously becomes smaller has been illustrated as the reduced-diameter portion, but the reduced-diameter portion may also be a reduced-diameter portion where the inner diameter becomes smaller stepwise. The hole of the second member 12 may also have a reduced-diameter portion in the same manner.

[0090] Industrial Applicability

[0091] According to the present disclosure, a method for manufacturing an electron source useful for efficiently manufacturing a fine electron source can be provided. Further, according to the present disclosure, an electron source capable of sufficiently suppressing the detachment of a member that emits electrons from a member that holds it and a transmitter including the same can be provided. Furthermore, according to the present disclosure, a device including the above-described transmitter can be provided.

[0092] Description of Reference Numerals

[0093] 1... Columnar portion, 1a... End face (electron emission surface), 2... Electron emission restricting member, 2a... Cylindrical portion, 2b... Base end portion, 2c... One end face, 2d... The other end face, 3, 4, 13... Holes, 4c... Tapered portion (reduced-diameter portion), 10, 10A... Electron sources, 11... First member (columnar portion), 11a... Protruding portion, 11c... Corner portion, 12... Second member, 20... Transmitter

Claims

1. A method for manufacturing an electron source, comprising the following steps: Step (A), preparing a plurality of first members, each of the plurality of first members having a columnar portion made of a first material having electron emission characteristics; Step (B), preparing a plurality of second members, each of the plurality of second members having a work function greater than that of the first material and each formed with a hole extending in a direction from one end face to the other end face; Step (C), selecting one of the plurality of first members and selecting one of the plurality of second members; Step (D), pressing the columnar portion of the selected first member into the inner peripheral surface without a notch of the hole of the selected second member; Step (E), scraping the portion of the columnar portion protruding from the hole so as to form an electron emission surface in such a manner that a flat surface is formed by the end face of the columnar portion and the end face of the second member, and the columnar portions of the plurality of first members each have a substantially quadrilateral cross-sectional shape, the holes of the plurality of second members each have a substantially circular cross-sectional shape, in Step (C), a set of first member and second member that satisfy the following conditions are selected from the plurality of first members and the plurality of second members, in Step (D), by pressing the columnar portion into the hole of the second member, a state is formed in which a part of the side surface of the columnar portion abuts against the inner surface of the hole of the second member, whereby the columnar portion is fixed to the second member, and the entire portion of the side surface of the columnar portion inserted into the hole is covered by the inner peripheral surface without a notch of the second member, <Condition> L 1 / R 1 >1…(1) In inequality (1), L 1 represents the length of the longer of the two diagonals of the approximate quadrilateral, and R 1 represents the diameter of the hole.

2. A method for manufacturing an electron source, comprising the following steps: Step (A), preparing a plurality of first members, each of the plurality of first members having a columnar portion made of a first material having electron emission characteristics; Step (B), preparing a plurality of second members, each of the plurality of second members having a work function greater than that of the first material and each formed with a hole extending in a direction from one end face to the other end face; Step (C), selecting one of the plurality of first members and selecting one of the plurality of second members; Step (D), pressing the columnar portion of the selected first member into the inner peripheral surface without a notch of the hole of the selected second member; and Step (E), scraping the portion of the columnar portion protruding from the hole so as to form an electron emission surface in such a manner that a flat surface is formed by the end face of the columnar portion and the end face of the second member, the columnar portions of the plurality of first members each have a substantially triangular cross-sectional shape, the holes of the plurality of second members each have a substantially circular cross-sectional shape, in Step (C), a set of first member and second member that satisfy the following conditions are selected from the plurality of first members and the plurality of second members, In step (D), by pressing the columnar portion into the hole of the second member, a state is achieved in which a part of the side surface of the columnar portion abuts against the inner surface of the hole of the second member, whereby the columnar portion is fixed to the second member, and the entire part of the side surface of the columnar portion that is inserted into the hole is covered by the inner peripheral surface of the second member that has no cutout. <Condition> The diameter R of the circumscribed circle of the substantially triangular shape 2 is larger than the diameter R of the hole 1 and when the substantially triangular shape is arranged in a circle having the same diameter as the diameter R of the hole 1 at least two angles of the substantially triangular shape are in contact with the circle.

3. An electron source comprising: a columnar portion made of a first material having electron emission characteristics; and a cylindrical portion made of a second material having a work function greater than that of the first material, the cylindrical portion being disposed so as to surround the columnar portion, the cylindrical portion having a hole extending in a direction from one end face to the other end face and having a substantially circular cross-sectional shape, the columnar portion having a substantially triangular or substantially quadrilateral cross-sectional shape and being fixed to the cylindrical portion in a state of abutting against the inner surface of the hole, a part of the columnar portion protruding from the hole is scraped to form an electron emission surface such that the end face of the columnar portion and the end face of the second member form a flat surface, and the entire part of the side surface of the columnar portion that is surrounded by the cylindrical portion is covered by the inner peripheral surface of the cylindrical portion that has no cutout.

4. A emitter comprising the electron source according to claim 3.

5. A emitter comprising an electron source manufactured by the manufacturing method of the electron source according to claim 1 or 2.

6. An apparatus comprising the emitter according to claim 4 or 5.

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