Emitter

Abstract

An emitter (1) includes: an electron source chip (10); a first filament (50) connected to a first position (10a) on a side surface of the electron source chip (10); a second filament (60) connected to a second position (10b) on the side surface of the electron source chip (10); two upper positive terminals (20a, b) to which first side surfaces (50a, b) at two locations of the first filament (50) are respectively connected; two upper negative terminals (20c, d) to which second side surfaces (60a, b) at two locations of the second filament (60) are respectively connected; one lower positive terminal (30a) electrically connected to the two upper positive terminals (20a, b); one lower negative terminal (30b) electrically connected to the two upper negative terminals (20c, d); and an insulator (40) that supports the upper positive terminals (20a, b), the upper negative terminals (20c, d), the lower positive terminal (30a), and the lower negative terminal (30b). The first position (10a) and the second position (10b) are different positions, the first side surfaces (50a, b) of the first filament (50) are respectively connected to side surfaces of the upper positive terminals (20a, b), and the second side surfaces (60a, b) of the second filament (60) are respectively connected to side surfaces of the upper negative terminals (20c, d).

Description

Emitter

[0001] The present invention relates to an emitter.

[0002] Electron sources are used in a variety of devices, such as electron beam lithography devices, electron beam writing devices, multi-electron beam systems, scanning electron microscopes (SEMs), transmission electron microscopes (TEMs), electron beam microanalyzers, and microfocus X-ray devices.

[0003] For example, Patent Document 1 discloses an electron source for the purpose of providing an electron source that operates stably for a long period of time, the electron source comprising: a <100> oriented single crystal rod made of tungsten or molybdenum having an electron emission surface with a {100} crystal plane exposed at its tip; a metal oxide layer covering the {100} crystal plane; a diffusion source for diffusing a raw material of the metal oxide layer; and a passage formed in the <100> oriented single crystal rod, which connects the diffusion source to the tip or the vicinity of the tip and serves as a passage for the diffusion of the raw material from the diffusion source.

[0004] In the case of a structure in which an electron source tip is connected to a single filament, such as the emitter shown in Patent Document 1, the position of the electron source changes little by little when a voltage is applied, and this change in the position of the electron source tip may result in a decrease in processing accuracy, etc.

[0005] Furthermore, Patent Document 2 discloses an electron gun having a multifilament heater composed of a first filament connected to two positive terminals and a second filament connected to two negative terminals, with the aim of providing an electron gun that is less susceptible to magnetic misalignment.

[0006] JP 2011-065790 A

[0007] As in Patent Document 2, a multifilament heater structure can theoretically suppress misalignment due to magnetism. However, if each filament is configured on the upper surface of the terminal, the contact points between the filament and the terminal are small and fragile, making it difficult to suppress misalignment due to magnetism for a long period of time.

[0008] Furthermore, Patent Document 2 shows an embodiment having four upper terminals, and it is presumed that the lower terminals in this embodiment are also four. However, some devices that use emitters correspond to two lower terminals, so a new structure with two lower terminals and four upper terminals is required.

[0009] The present invention has been made in view of the above problems, and has as its object to provide an electron source having excellent positional stability of the electron source tip during use, and a method for manufacturing the same.

[0010] That is, the present invention is as follows: [1] An emitter comprising: an electron source chip, a first filament connected to a first position on a side surface of the electron source chip, a second filament connected to a second position on a side surface of the electron source chip, two upper positive terminals to which two first side surfaces of the first filament are respectively connected, two upper negative terminals to which two second side surfaces of the second filament are respectively connected, one lower positive terminal electrically connected to the two upper positive terminals, one lower negative terminal electrically connected to the two upper negative terminals, and an insulator carrying the upper positive terminal, the upper negative terminal, the lower positive terminal, and the lower negative terminal, wherein the first position and the second position are different positions, and the first side surfaces of the first filament are respectively connected to side surfaces of the upper positive terminal, and the second side surfaces of the second filament are respectively connected to side surfaces of the upper negative terminal. [2] The emitter according to [1], wherein, in a plan view of a first surface perpendicular to the tip direction of the electron source tip, the two upper positive terminals and the two upper negative terminals are arranged so that a line segment connecting the centers of the two upper positive terminals intersects with a line segment connecting the centers of the two upper negative terminals. [3] The emitter according to [1] or [2], wherein, in a plan view of the first surface perpendicular to the tip direction of the electron source tip, the first filament and the second filament are arranged so as to intersect. [4] The emitter according to [3], wherein, in a plan view of the first surface, the angle θ1 formed by the projection lines of the first filament and the second filament is 80° or more and 90° or less. [5] The emitter according to [3], wherein, in a plan view of the first surface, the angle θ1 formed by the projection lines of the first filament and the second filament is less than 80°. [6] The emitter described in any one of [1] to [5], wherein, in a plan view of a first surface perpendicular to the tip direction of the electron source tip, the first filament is arranged so that a line segment connecting the side surfaces of the two upper positive terminals to which the first side surface of the first filament is connected intersects with a line segment connecting the centers of the two upper positive terminals.[7] The emitter according to any one of [1] to [6], wherein, in a plan view of a first surface perpendicular to a tip direction of the electron source tip, the second filament is arranged so that a line segment connecting the side surfaces of the two upper negative terminals to which the second side surface of the second filament is connected intersects with a line segment connecting the centers of the two upper negative terminals. [8] The emitter according to any one of [1] to [5] and [7], wherein, in a plan view of the first surface perpendicular to a tip direction of the electron source tip, the first filament is arranged so that a line segment connecting the side surfaces of the two upper positive terminals to which the first side surface of the first filament is connected does not intersect with a line segment connecting the centers of the two upper positive terminals. [9] The emitter according to any one of [1] to [6] and [8], wherein, in a plan view of a first surface perpendicular to a tip direction of the electron source tip, the second filament is arranged so that a line segment connecting the side surfaces of the two upper negative terminals to which the second side surface of the second filament is connected does not intersect with a line segment connecting the centers of the two upper negative terminals.

[10] The emitter according to any one of [1] to [9], wherein, in a plan view of the first surface perpendicular to a tip direction of the electron source tip, the first filament and the second filament are arranged so that at least the side surface of the upper positive terminal to which the first side surface of the first filament is connected faces the side surface of the upper negative terminal to which the second side surface of the second filament is connected.

[11] The emitter according to any one of [1] to [9], wherein, in a plan view of a first surface perpendicular to a tip direction of the electron source tip, the first filament and the second filament are arranged so that the side of the upper positive terminal to which the first side surface of the first filament is connected does not face the side of the upper negative terminal to which the second side surface of the second filament is connected.

[12] The emitter according to any one of [1] to

[11] , wherein the first filament is joined at a position closer to the tip of the electron source tip than the second filament.

[13] The emitter according to any one of [1] to

[11] , wherein the second filament is joined at a position closer to the tip of the electron source tip than the first filament.

[14] The emitter according to any one of [1] to

[13] , wherein the pair of upper positive terminals have positive terminal connecting portions that electrically connect the pair of upper positive terminals, and the pair of upper negative terminals have negative terminal connecting portions that electrically connect the pair of upper negative terminals.

[0011] According to the present invention, it is possible to provide an emitter that has excellent positional stability of the electron source tip during use.

[0012] Fig. 1 is a schematic perspective view of an emitter of this embodiment; Fig. 2 is a top view of an insulator viewed from the electron source chip side at a first surface perpendicular to the tip direction of the electron source chip; Fig. 3 is a top view of an insulator viewed from the electron source chip side at a first surface perpendicular to the tip direction of the electron source chip; Fig. 4 is a top view of an insulator viewed from the electron source chip side at a first surface perpendicular to the tip direction of the electron source chip; Fig. 5 is a top view of an insulator viewed from the electron source chip side at a first surface perpendicular to the tip direction of the electron source chip.

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this embodiment and various modifications are possible without departing from the spirit of the present invention. Note that the dimensional ratios in the drawings are not limited to those shown in the drawings.

[0014] In this embodiment, the "X direction," "Y direction," "Z direction," and "XY plane direction" are defined as necessary. Here, the "Z direction" is a direction parallel to the direction in which electrons are emitted from the tip of the electron source tip 10. The direction in which electrons are emitted from the tip of the electron source tip 10 is also referred to as the "Z+ direction," and the direction opposite to the Z+ direction is also referred to as the "Z- direction." Furthermore, unless otherwise specified, the "Z direction" is parallel to the extension direction of the upper terminal 20 and the lower terminal 30.

[0015] Furthermore, the "XY plane direction" is a plane direction that intersects with the Z direction. The XY plane direction may be parallel to the surface 40a from which the upper terminal 20 of the insulator 40 extends and the surface 40b from which the lower terminal 30 extends. Furthermore, unless otherwise specified, the Z direction may be perpendicular to the XY plane direction. The "X direction" and the "Y direction" are directions that intersect with each other within the XY plane. The "X direction" refers to the direction connecting the centers of the upper positive terminals 20a and 20b, and the "Y direction" refers to the direction connecting the centers of the upper negative terminals 20c and 20d. The X direction and the Y direction do not have to be perpendicular to each other.

[0016] Terms that mean shapes and / or geometric conditions do not need to be bound by strict meanings and may be interpreted to include a range within which similar functions may be expected. For example, "parallel" and / or "orthogonal" fall under the above terms.

[0017] When a certain configuration is expressed as being "above," "below," "upper," "lower," "above," or "below" another configuration, this may include a configuration in which the certain configuration is in direct contact with the other configuration, and a configuration in which another configuration is included between the certain configuration and the other configuration. In other words, a configuration in which another configuration is included between the certain configuration and the other configuration may be expressed as a configuration indirectly in contact with the other configuration. Furthermore, the expressions "above," "upper side," or "above" are interchangeable with the expressions "below," "lower side," or "below." In other words, the up-down direction may be reversed. The same applies to left and right.

[0018] When the same or similar symbols are used to denote identical parts and / or parts having similar functions, repeated descriptions may be omitted. Also, the dimensional ratios in the drawings may differ from the actual ratios. Also, some of the configurations of the embodiments may be omitted from the drawings.

[0019] FIG. 1 shows an emitter 1 of this embodiment. As shown in FIG. 1 , the emitter 1 of this embodiment includes an electron source chip 10, a first filament 50 connected to a first position 10 a on a side surface of the electron source chip 10, a second filament 60 connected to a second position 10 b on a side surface of the electron source chip 10, two upper positive terminals 20 a, 20 b to which the two first side surfaces 50 a, 50 b of the first filament 50 are connected, respectively, two upper negative terminals 20 c, 20 d to which the two second side surfaces 60 a, 60 b of the second filament are connected, respectively, one lower positive terminal 30 a electrically connected to the two upper positive terminals 20 a, 20 b, one lower negative terminal 30 b electrically connected to the two upper negative terminals 20 c, 20 d, and an insulator 40 supporting the upper positive terminals 20 a, 20 b, the upper negative terminals 20 c, 20 d, the lower positive terminal 30 a, and the lower negative terminal 30 b.

[0020] The upper positive terminals 20a, 20b and the upper negative terminals 20c, 20d are collectively referred to as "upper terminals 20." The lower positive terminal 30a and the lower negative terminal 30b are collectively referred to as "lower terminals 30." Each component of the emitter 1 of this embodiment will be described in more detail below.

[0021] The electron source tip 10 is made of a material that emits electrons when heated and an electric field is applied, and may have an electron emission surface at its tip. The electron emission material is not particularly limited, but examples thereof include tungsten, molybdenum, tantalum, rhenium, and LaB. ６ Lanthanum borides such as CeB ６ Cerium borides such as Ir ２ and iridium cerium such as Ce.

[0022] The electron source tip may also have a diffusion source 11. The diffusion source 11 is not particularly limited, but may be, for example, a composite oxide of barium oxide or scandium oxide.

[0023] The first filament 50 and the second filament 60 are connected to the electron source chip 10 as filaments for heating the electron source chip 10. More specifically, the first filament 50 and the second filament 60 may be connected to a heating power supply via the upper terminal 20 and the lower terminal 30, and current may flow from the heating power supply to heat the electron source chip 10. The current flowing through the first filament 50 and the second filament 60 may be set so that the electron source is at about 1800 K, for example.

[0024] Figure 1 shows an embodiment in which the first filament 50 is joined at a position closer to the tip of the electron source chip 10 than the second filament 60, but this is not limited to this, and the second filament 60 may be joined at a position closer to the tip of the electron source chip 10 than the first filament 50.

[0025] The distance between the first position 10a on the side of the electron source chip 10 to which the first filament 50 is connected and the second position 10b on the side of the electron source chip 10 to which the second filament 60 is connected is preferably 10 to 500 μm, and may be 50 to 300 μm. Note that this distance refers to the distance of the gap between the first filament 50 and the second filament 60.

[0026] Furthermore, tungsten or graphite filaments, carbon heaters, etc. may be used as the first filament 50 and the second filament 60. Furthermore, the materials constituting the first filament 50 and the second filament 60 may be the same or different.

[0027] The first filament 50 has first side surfaces 50a and 50b connected to the two upper positive terminals 20a and 20b, respectively, and an arbitrary portion between the first side surfaces 50a and 50b is connected to a first position 10a on the side surface of the electron source chip 10. The second filament 60 has second side surfaces 60a and 60b connected to the two upper negative terminals 20c and 20d, respectively, and an arbitrary portion between the second side surfaces 60a and 60b is connected to a second position 10b on the side surface of the electron source chip 10.

[0028] 1, in the emitter 1 of this embodiment, two upper positive terminals 20a, 20b are electrically connected to one lower positive terminal 30a, and two upper negative terminals 20c, 20d are electrically connected to one lower negative terminal 30b. As a result, the emitter 1 has a structure that converts two lower terminals 30 into four upper terminals 20.

[0029] The manner in which the two upper positive terminals 20a, 20b and the single lower positive terminal 30a are connected is not particularly limited, and examples thereof include a manner in which the two upper positive terminals 20a, 20b are each connected to the lower positive terminal 30a; and a manner in which, as shown in FIG. 1, the single upper positive terminal 20b is connected to the lower positive terminal 30a, and the upper positive terminals 20a and 20b are linked together.

[0030] Here, the connection between the upper positive terminals 20a, 20b and the lower positive terminal 30a is referred to as the upper and lower positive terminal connection part 80a, and the connection part electrically connecting the pair of upper positive terminals 20a, 20b is referred to as the upper positive terminal connection part 81a.

[0031] The manner in which the two upper negative terminals 20c, 20d and the single lower negative terminal 30b are connected is not particularly limited, but examples include a manner in which the two upper negative terminals 20c, 20d are each connected to the lower negative terminal 30b; or a manner in which, as shown in FIG. 1, the single upper negative terminal 20c is connected to the lower negative terminal 30b, and the upper negative terminal 20c and the upper negative terminal 20d are linked together.

[0032] Here, the connection portion between upper negative terminals 20c, 20d and lower negative terminal 30b is referred to as upper and lower negative terminal connection portion 80b, and the connection portion electrically connecting the pair of upper negative terminals 20c, 20d is referred to as upper negative terminal connection portion 81b.

[0033] In the example shown in FIG. 1 , the upper positive terminal connecting portion 81 a is located on the Z+ direction surface of the insulator 40, and the upper negative terminal connecting portion 81 b is located inside the insulator 40, but this is not limited to this. In addition to the upper positive terminal connecting portion 81 a, the upper negative terminal connecting portion 81 b may also be located on the Z+ direction surface of the insulator 40 so as to bypass the upper positive terminal connecting portion 81 a and the upper positive terminals 20 a, 20 b.

[0034] With the above structure, during heating, electrons are supplied from the lower negative terminal 30b to the two upper negative terminals 20c, 20d, and then from the second side surfaces 60a, 60b of the second filament 60 toward the second position 10b on the side surface of the electron source chip 10. Then, electrons flow from the first position 10a on the side surface of the electron source chip 10 toward the first side surfaces 50a, 50b of the first filament 50, and then from the upper positive terminals 20a, 20b to the lower positive terminal 30a.

[0035] The emitter 1 of this embodiment has a structure in which a filament is stretched across two upper positive terminals 20a, 20b and two upper negative terminals 20c, 20d, and the two filaments support the electron source tip 10. Therefore, the electron source tip is held more stably than in a structure in which the electron source tip 10 is supported by a single filament whose positive and negative terminals are connected.

[0036] The electron gun comprises a magnetic lens that forms a magnetic field and an emitter 1. This allows electrons to be emitted from the tip of the emitter 1 through the magnetic lens toward the target. At this time, the emitter 1 is placed within the magnetic field formed by the magnetic lens, and a magnetic force acts on the filament due to the magnetic field. This can cause the emitter 1 to shift in position, which can impair the positional stability of the electron source tip.

[0037] In particular, since magnetic repulsion is likely to act in the XY plane direction, when the first side surfaces 50a, 50b of the first filament 50 are in contact with the upper surfaces of the two upper positive terminals 20a, 20b and the contact area is small, or when the second side surfaces 60a, 60b of the second filament 60 are in contact with the upper surfaces of the two upper negative terminals 20c, 20d and the contact area is small, the positional stability of the electron source tip may be further impaired.

[0038] In contrast, in this embodiment, the first sides 50a, 50b of the first filament 50 are connected to the sides 20a', 20b' of the upper positive terminals 20a, 20b, respectively, and the second sides 60a, 60b of the second filament 60 are connected to the sides 20c', 20d' of the upper negative terminals 20c, 20d, respectively.

[0039] The method for connecting the side of the filament and the side of the terminal is not particularly limited, but spot welding, for example, can be used.

[0040] FIG. 2 shows a plan view of the insulator 40 viewed in the Z-direction from the electron source chip 10 side. In FIG. 2, the arrows C indicate the current flow and the direction F of the force generated by the current. As shown in FIG. 2, the first side surfaces 50a and 50b of the first filament 50 are connected to the side surfaces 20a' and 20b' of the upper positive terminals 20a and 20b, respectively, and the second side surfaces 60a and 60b of the second filament 60 are connected to the side surfaces 20c' and 20d' of the upper negative terminals 20c and 20d, respectively. This configuration shows that, within the magnetic field formed by the magnetic lens, the magnetic forces acting on the filaments in the XY plane are in opposition. As shown on the left and right sides of FIG. 2, this opposition also holds when the current flows in the opposite direction.

[0041] Furthermore, by joining the ends of the filaments to the side surfaces in this manner, the contact areas between the first side surfaces 50a, 50b and the upper positive terminals 20a, 20b and the contact areas between the second side surfaces 60a, 60b and the upper negative terminals 20c, 20d are increased, which strengthens the connections between the first filament 50 and the upper positive terminals 20a, 20b and the second filament 60 and the upper negative terminals 20c, 20d, and also reduces positional shifts during long-term use.

[0042] Furthermore, by connecting the first side surfaces 50a and 50b to the side surfaces 20a' and 20b' and connecting the second side surfaces 60a and 60b to the side surfaces 20c' and 20d', even if the filaments are subjected to a magnetic force in the XY plane direction within the magnetic field formed by the magnetic lens, the upper terminal 20 can support the first filament 50 and the second filament 60 by opposing the force. For example, as shown on the right side of Figure 2, in the upper positive terminal 20a, a force F from the first filament 50 is applied to the side surface 20a', and the upper positive terminal 20a supports the first filament 50.

[0043] This further improves the positional stability of the electron source tip, and as a result, when used in various devices such as electron beam lithography devices, electron beam writing devices, multi-electron beam systems, scanning electron microscopes (SEMs), transmission electron microscopes (TEMs), electron beam microanalyzers, and microfocus X-ray devices, the accuracy of the electron beam irradiation position is further improved.

[0044] The material of the insulator 40 in this embodiment is not particularly limited, but may be, for example, alumina. The method of bonding the upper terminal 20 and the lower terminal 30 to the insulator 40 is not particularly limited, but may be, for example, brazing.

[0045] The emitter 1 of this embodiment will be further described below with reference to Fig. 3 and Fig. 4. Fig. 3 and Fig. 4 show top views of the insulator 40, viewed from the electron source tip 10 side, at a first surface perpendicular to the tip direction of the electron source tip 10. The first surface is synonymous with the "XY plane."

[0046] In a plan view of the first surface, the projection lines of the first filaments 50 and the second filaments 60 onto the first surface are preferably arranged to intersect. As shown in Fig. 3A, the angle θ1 formed by the projection lines of the first filaments 50 and the second filaments 60 is preferably 80° or more and 90° or less, 82° or more and 90° or less, or 84° or more and 90° or less. Furthermore, as shown in Fig. 3B, the angle θ1 formed by the projection lines of the first filaments 50 and the second filaments 60 on the first surface is preferably less than 80°, 10° or more and 75° or less, 20° or more and 70° or less, or 30° or more and 65° or less.

[0047] In this embodiment, the term "plan view" refers to viewing the first surface from a plane along the first surface. In the plan view of the first surface, the first filaments 50 and the second filaments 60 are projected onto the first surface.

[0048] As shown in FIG. 3A , in a plan view of the first surface, the two upper positive terminals 20 a, 20 b and the two upper negative terminals 20 c, 20 d may be arranged such that a line segment l1 connecting the centers of the two upper positive terminals 20 a, 20 b intersects with a line segment l2 connecting the centers of the two upper negative terminals 20 c, 20 d.

[0049] The angle θ2 formed by the line segment l1 and the line segment l2 is preferably 80° or more and 90° or less, or may be 82° or more and 90° or less, or 84° or more and 90° or less. Furthermore, the angle θ2 is preferably less than 80°, or may be 10° or more and 75° or less, or 20° or more and 70° or less, or 30° or more and 65° or less.

[0050] 3A and 3B , in a plan view of the first surface, the first filament 50 may be arranged so that a line segment connecting the side surfaces 20a' and 20b' of the two upper positive terminals 20a and 20b to which the first side surfaces 50a and 50b of the first filament 50 are connected intersects with a line segment 11 connecting the centers of the two upper positive terminals 20a and 20b. Note that the line segment connecting the side surfaces 20a' and 20b' is equal to the length of the first filament 50.

[0051] 3A and 3B , in a plan view of the first surface, the second filament 60 may be arranged such that a line segment connecting the side surfaces 20c' and 20d' of the two upper negative terminals 20c and 20d to which the second side surfaces 60a and 60b of the second filament 60 are connected intersects with a line segment l2 connecting the centers of the two upper negative terminals 20c and 20d. Note that the line segment connecting the side surfaces 20c' and 20d' is equal to the second filament 60.

[0052] In a plan view of the first surface, the first filament 50 may be arranged so that the line segment connecting the side surfaces 20a', 20b' of the two upper positive terminals 20a, 20b to which the first side surfaces 50a, 50b of the first filament 50 are connected does not intersect with the line segment l1 connecting the centers of the two upper positive terminals. Note that, in this case, the line segment connecting the side surfaces 20a', 20b' is equal to the first filament 50.

[0053] As shown in Fig. 4, in a plan view of the first surface, the second filament 60 may be arranged so that the line segment connecting the side surfaces 20c', 20d' of the two upper negative terminals 20c, 20d to which the second side surfaces 60a, 60b of the second filament 60 are connected does not intersect with the line segment l2 connecting the centers of the two upper negative terminals. Note that the line segment connecting the side surfaces 20c', 20d' is the same as the second filament 60. Note that the first filament 50 and the like are omitted from Fig. 4.

[0054] 3B , in a plan view of the first surface, the first filament 50 and the second filament 60 may be arranged so that the side surfaces 20a' and 20b' of the upper positive terminals 20a and 20b to which the first side surfaces 50a and 50b of the first filament 50 are connected at least face each other, and the side surfaces 20c' and 20d' of the upper negative terminals 20c and 20d to which the second side surfaces 60a and 60b of the second filament 60 are connected at least face each other. Here, "at least face each other" means that, for example, the side surfaces 20a' and 20c' face each other as shown in FIG. 3B , and it is not necessary that the side surfaces 20a' and 20d' face each other.

[0055] As shown in FIG. 3A , in a plan view of the first surface, the first filament 50 and the second filament 60 may be arranged so as not to face the side surfaces 20a′, 20b′ of the upper positive terminals 20a, 20b to which the first side surfaces 50a, 50b of the first filament 50 are connected, and the side surfaces 20c′, 20d′ of the upper negative terminals 20c, 20d to which the second side surfaces 60a, 60b of the second filament 60 are connected.

[0056] The present invention has industrial applicability as an emitter.

[0057] 1 Emitter, 10... Electron source tip, 10a... First position, 10b... Second position, 11... Diffusion source, 20... Upper terminal, 20a... Upper positive terminal, 20a'... Side, 20b... Upper positive terminal, 20b'... Side, 20c... Upper negative terminal, 20c'... Side, 20d... Upper negative terminal, 20d'... Side, 30... Lower terminal, 30a... Lower positive terminal, 30b... Lower negative terminal, 40... Insulator, 40a... Surface, 40b... Surface, 50... First filament, 50a... First side, 50b... First side, 60... Second filament, 60a... Second side, 60b... Second side, 80a... Upper and lower positive terminal connection portion, 80b... Upper and lower negative terminal connection portion, 81a... Upper positive terminal connection portion, 81b... Upper negative terminal connection portion

Claims

1. An emitter comprising: an electron source chip; a first filament connected to a first position on a side of the electron source chip; a second filament connected to a second position on a side of the electron source chip; two upper positive terminals to which two first side surfaces of the first filament are respectively connected; two upper negative terminals to which two second side surfaces of the second filament are respectively connected; one lower positive terminal electrically connected to the two upper positive terminals; one lower negative terminal electrically connected to the two upper negative terminals; and an insulator carrying the upper positive terminal, the upper negative terminal, the lower positive terminal, and the lower negative terminal, wherein the first position and the second position are different positions, and the first side surfaces of the first filament are respectively connected to side surfaces of the upper positive terminal, and the second side surfaces of the second filament are respectively connected to side surfaces of the upper negative terminal.

2. The emitter described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the two upper positive terminals and the two upper negative terminals are arranged so that a line segment connecting the centers of the two upper positive terminals intersects with a line segment connecting the centers of the two upper negative terminals.

3. The emitter according to claim 1, wherein, in a plan view of a first surface perpendicular to a tip direction of the electron source tip, projection lines of the first filament and the second filament onto the first surface are arranged to intersect.

4. The emitter according to claim 3, wherein, in a plan view of the first surface, an angle θ1 between the projection lines of the first filament and the second filament is greater than or equal to 80° and less than or equal to 90°.

5. The emitter according to claim 3, wherein, in a plan view of the first surface, an angle θ1 between the projection lines of the first filament and the second filament is less than 80°.

6. The emitter described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the first filament is arranged so that a line segment connecting the side surfaces of the two upper positive terminals to which the first side surface of the first filament is connected intersects with a line segment connecting the centers of the two upper positive terminals.

7. An emitter as described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the second filament is arranged so that a line segment connecting the side surfaces of the two upper negative terminals to which the second side surface of the second filament is connected intersects with a line segment connecting the centers of the two upper negative terminals.

8. The emitter described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the first filament is positioned so that a line segment connecting the side surfaces of the two upper positive terminals to which the first side surface of the first filament is connected does not intersect with a line segment connecting the centers of the two upper positive terminals.

9. An emitter as described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the second filament is positioned so that a line segment connecting the side surfaces of the two upper negative terminals to which the second side surface of the second filament is connected does not intersect with a line segment connecting the centers of the two upper negative terminals.

10. The emitter described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the first filament and the second filament are arranged so that at least the side of the upper positive terminal to which the first side of the first filament is connected faces the side of the upper negative terminal to which the second side of the second filament is connected.

11. The emitter described in claim 1, wherein, in a planar view of a first surface perpendicular to the tip direction of the electron source tip, the first filament and the second filament are arranged so that the side of the upper positive terminal to which the first side of the first filament is connected does not face the side of the upper negative terminal to which the second side of the second filament is connected.

12. The emitter of claim 1, wherein the first filament is joined at a position closer to the tip of the electron source tip than the second filament.

13. The emitter of claim 1, wherein the second filament is joined at a position closer to the tip of the electron source tip than the first filament.

14. The emitter of claim 1, wherein the pair of upper positive terminals have positive terminal connections that electrically connect the pair of upper positive terminals, and the pair of upper negative terminals have negative terminal connections that electrically connect the pair of upper negative terminals.

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