Emitter

Abstract

This emitter includes: an insulator; a pair of terminals extending along a first direction and fixed to the insulator so as to face each other in a second direction perpendicular to the first direction; a filament fixed to the pair of terminals; and a chip part formed of an electron emission material and fixed to the filament. Each of the pair of terminals has, on one side in a third direction perpendicular to the first direction and the second direction, an inclined surface inclined with respect to the first direction further toward the other side in the third direction in conformity with an increase in the distance from the insulator. The filament is fixed to the pair of terminals on the inclined surface.

Description

Emitter

[0001] One aspect of the present disclosure relates to an emitter.

[0002] Patent Document 1 describes an emitter including an insulator, a pair of terminals fixed to the insulator, a filament fixed to the pair of terminals, and a tip fixed to the filament. In this emitter, the tip is heated by passing current through the filament via the terminals, and an electron beam is emitted from the tip.

[0003] Patent No. 4789122

[0004] In the emitter described above, it is required to position the tip portion at a target position with high accuracy and stability in order to suppress deviations in the irradiation direction and irradiation position of the electron beam emitted from the tip portion.

[0005] Therefore, an object of one aspect of the present disclosure is to provide an emitter in which a tip portion is fixed accurately and stably.

[0006] An emitter according to one aspect of the present disclosure is [1] "an emitter comprising: an insulator; a pair of terminals extending along a first direction and fixed to the insulator so as to face each other in a second direction perpendicular to the first direction; a filament fixed to the pair of terminals; and a tip portion formed of an electron emitting material and fixed to the filament, wherein each of the pair of terminals has an inclined surface on one side in a third direction perpendicular to the first direction and the second direction that is inclined with respect to the first direction so as to move toward the other side in the third direction as it moves away from the insulator; and the filament is fixed to the pair of terminals at the inclined surface."

[0007] In this emitter, each of the pair of terminals has an inclined surface on one side in the third direction that is inclined with respect to the first direction so as to move toward the other side in the third direction as it moves away from the insulator, and the filament is fixed to the pair of terminals at the inclined surface. As a result, for example, by fixing the filament to the inclined surface while aligning it along the inclined surface, the filament can be fixed to the pair of terminals with high precision. Fixing the filament with high precision results in high precision fixation of the tip portion. Furthermore, because the filament is fixed to the inclined surface, the filament is less likely to move after fixation, allowing the filament and the tip portion to be stably fixed. Furthermore, fixing the filament to the inclined surface ensures a large area for fixing the filament, making it easy to fix the filament to the terminal. As described above, in this emitter, the tip portion can be fixed with high precision and stability.

[0008] An emitter according to one aspect of the present disclosure may be [2] "the emitter according to [1], in which, in each of the pair of terminals, the inclined surface does not protrude from the outer surface of the terminal when viewed from the first direction." In this case, the inclined surface can be formed, for example, by cutting a part of the terminal, making it easy to form the inclined surface.

[0009] An emitter according to one aspect of the present disclosure may be [3] "the emitter according to [1] or [2], wherein the inclined surface of each of the pair of terminals is continuous with the outer surface of the terminal." In this case, the filament can be more easily fixed to the inclined surface than when the inclined surface is formed by, for example, the bottom surface of a groove formed in the terminal.

[0010] An emitter according to one aspect of the present disclosure may be [4] "the emitter according to any one of [1] to [3], wherein, in each of the pair of terminals, the inclined surface does not extend to the end of the terminal opposite the insulator." In this case, it is possible to prevent sharp portions (e.g., corners) from being formed around the tip portion, and the emitter can operate stably. In addition, it is possible to ensure a large area for the end face of the terminal opposite the insulator, which makes it easy to position the end face by butting it against another member.

[0011] According to one aspect of the present disclosure, it is possible to provide an emitter in which a tip portion is fixed accurately and stably.

[0012] 1A and 1B are a front view and a side view of an emitter according to an embodiment;

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and redundant description will be omitted.

[0014] As shown in FIG. 1 , the emitter 1 includes an insulator 2, a pair of terminals 3, a filament 4, and a tip portion 5 (electron source). The emitter 1 is, for example, a thermal field emission type emitter. The emitter 1 constitutes an electron gun together with a suppressor electrode, an extraction electrode, and the like, and can be used in electron microscopes, semiconductor manufacturing equipment, inspection equipment, processing equipment, and the like. In the emitter 1, the tip portion 5 is heated by passing current through the filament 4 via the pair of terminals 3, and an electron beam is emitted from the tip of the tip portion 5. The following description will be made with reference to the X direction (second direction), the Y direction (third direction) perpendicular to the X direction, and the Z direction (first direction) perpendicular to the X and Y directions shown in FIG. 1 .

[0015] The insulator 2 is formed, for example, in a substantially cylindrical shape from an insulating material. The terminal 3 is formed, for example, in a rod shape from a metal material such as tungsten, kovar, or titanium. In this example, the terminal 3 is formed in a cylindrical shape and extends straight along the Z direction. The terminal 3 penetrates the insulator 2 along the Z direction and is fixed to the insulator 2 at its middle portion. The terminal 3 has a protrusion 31 that protrudes from the insulator 2 to one side in the Z direction (the upper side in Figures 1 and 2 ). The pair of terminals 3 face each other with a gap in the X direction.

[0016] An inclined surface 32 is formed on the protruding portion 31 of each terminal 3. The inclined surface 32 is formed on one side of the protruding portion 31 in the Y direction (the front side of the paper in FIG. 1) (the left side in FIG. 2). The inclined surface 32 is inclined with respect to the Z direction so that the farther it is from the insulator 2 (the closer it is to one side in the Z direction), the more it approaches the other side in the Y direction (the farther back of the paper in FIG. 1) (the right side in FIG. 2). The inclined surface 32 is, for example, an inclined flat surface.

[0017] The inclined surface 32 is formed in the middle of the protruding portion 31 in the Z direction and does not reach the end of the terminal 3 opposite the insulator 2 (the upper end in FIGS. 1 and 2 ). The inclined surface 32 is formed, for example, by cutting out a portion of the cylindrical terminal 3, but may also be formed into this shape without cutting out. The inclined surface 32 does not protrude from the outer surface of the terminal 3 when viewed from the Z direction. In other words, the inclined surface 32 is located inside the outer edge of the terminal 3 when viewed from the Z direction. The inclined surface 32 is also continuous with the outer surface of the terminal 3.

[0018] The position and inclination angle of the inclined surface 32 are set so that the tip portion 5 is positioned at a target position when the filament 4 is fixed to the inclined surface 32. For example, the position and inclination angle of the inclined surface 32 are set so that the tip portion 5 overlaps the center of the terminal 3 when viewed from the X direction, as shown in Fig. 2. The inclination angle of the inclined surface 32 with respect to the Z direction is, for example, about 5°. The length from the inclined surface 32 to the end of the terminal 3 opposite the insulator 2 is, for example, about 1.5 mm.

[0019] The filament 4 is formed in an arch shape, extends between the pair of terminals 3, and is fixed at both ends to the pair of terminals 3. The filament 4 has an apex 41 and a pair of extension portions 42 that extend from the apex 41 toward both ends. The apex 41 is curved so as to be convex toward one side in the Z direction (the side opposite the insulator 2 and terminal 3). In this example, the extension portions 42 extend straight. The filament 4 is fixed to the protrusions 31 of each terminal 3 at the extension portions 42. The extension portions 42 are joined to the protrusions 31 by, for example, spot welding.

[0020] More specifically, in this example, the extension portion 42 is fixed to the terminal 3 at the inclined surface 32. The extension portion 42 is fixed to the inclined surface 32 by welding while being aligned with the inclined surface 32. As a result, the inclination angle of the extension portion 42 is determined by the inclined surface 32, and the extension portion 42 is inclined with respect to the Z direction so that the extension portion 42 is inclined toward one side in the Z direction (the upper side in FIG. 2 ) and the other side in the Y direction (the right side in FIG. 2 ).

[0021] The filament 4 is made of, for example, a high-melting-point metal having a melting point of 2200° C. or higher. In this example, the filament 4 is made of tungsten. Other examples of the material of the filament 4 include an alloy of tungsten and a high-melting-point metal (e.g., rhenium). The material of the filament 4 may also be tungsten doped with an alkali metal (e.g., potassium) for tissue stabilization.

[0022] The tip portion 5 is fixed to the top 41 of the filament 4. The tip portion 5 is formed, for example, in a rod shape from an electron-emitting material. Examples of materials for the tip portion 5 include high-melting-point metals such as tungsten, tantalum, and hafnium, as well as their oxides, carbides, and nitrides, rare earth borides such as lanthanum boride (LaB6) and cerium boride (CeB6), and precious metal-rare earth alloys such as iridium cerium. In this example, the tip portion 5 is fixed so as to extend along the Z direction. As described above, in this example, as shown in FIG. 2, the tip portion 5 is positioned so as to overlap the center of the terminal 3 when viewed from the X direction. [Operation and Effects]

[0023] In the emitter 1, each terminal 3 has an inclined surface 32 on one side in the Y direction (third direction) (the front side of the paper in FIG. 1 ) (the left side in FIG. 2 ) that is inclined with respect to the Z direction (first direction) so that the further away from the insulator 2 it is, the closer it is to the other side in the Y direction. The filament 4 is fixed to the pair of terminals 3 at the inclined surface 32. As a result, for example, by fixing the filament 4 to the inclined surface 32 while aligning it along the inclined surface 32, the filament 4 can be fixed to the pair of terminals 3 with high precision. By fixing the filament 4 with high precision, the tip portion 5 can be fixed with high precision. Furthermore, since the filament 4 is fixed to the inclined surface 32, the filament 4 is less likely to move after being fixed, and the filament 4 and the tip portion 5 can be stably fixed. Furthermore, by fixing the filament 4 to the inclined surface 32, a large area can be secured for fixing (welding) the filament 4, and the filament 4 can be easily fixed to the terminal 3. As described above, in the emitter 1, the tip portion 5 can be fixed with high precision and stability.

[0024] In each terminal 3, the inclined surface 32 does not protrude from the outer surface of the terminal 3 when viewed from the Z direction. This allows the inclined surface 32 to be formed, for example, by cutting a part of the terminal 3, making it easy to form the inclined surface 32.

[0025] In each terminal 3, the inclined surface 32 is continuous with the outer surface of the terminal 3. This makes it easier to fix the filament 4 to the inclined surface 32 compared to, for example, a case in which the inclined surface 32 is formed by the bottom surface of a groove formed in the terminal 3.

[0026] In each terminal 3, the inclined surface 32 does not reach the end of the terminal 3 opposite the insulator 2. This makes it possible to prevent sharp parts (e.g., corners) from being formed around the tip portion 5, and ensures stable operation of the emitter 1. In addition, a large area can be secured for the end face of the terminal 3 opposite the insulator 2, making it easy to position the end face by butting it against another member.

[0027] In the emitter 1, the extension 42 of the filament 4, which extends from the top 41 (the portion fixed to the tip portion 5) to the terminal 3, is formed straight. In other words, no bends are formed in the extension 42. This makes it possible to suppress displacement of the filament 4 due to thermal expansion, even when the filament 4 reaches a high temperature (for example, about 1500°C) due to the passage of current during operation of the emitter 1. Furthermore, residual stress is less likely to occur in the extension 42, making it possible to stably fix the filament 4 and the tip portion 5.

[0028] The present disclosure is not limited to the above-described embodiments and modifications. For example, the materials and shapes of the components are not limited to those described above, and various materials and shapes can be adopted.

[0029] The inclined surface 32 may protrude from the outer surface of the terminal 3 when viewed from the Z direction. For example, the inclined surface 32 may be formed on a protruding portion that protrudes from the terminal 3 to one side in the Y direction. The inclined surface 32 may not be continuous with the outer surface of the terminal 3. For example, a groove may be formed in the terminal 3, and the inclined surface 32 may be formed by the bottom surface of the groove. In this case, the side surface of the groove is interposed between the inclined surface 32 and the terminal 3, and the inclined surface 32 may not be continuous with the outer surface of the terminal 3. The inclined surface 32 may be formed to reach the end of the terminal 3 opposite the insulator 2.

[0030] Although the emitter 1 includes one filament 4 (first filament 4) in the above embodiment, the emitter 1 may include multiple (e.g., two) filaments 4. In this case, for example, an inclined surface 32 is also formed on the other side in the Y direction (the farther side of the paper in FIG. 1 ) (the right side in FIG. 2 ) of the protruding portion 31 of each terminal 3. This inclined surface 32 is inclined with respect to the Z direction so as to approach one side in the Y direction as it becomes farther from the insulator 2. In other words, the terminals 3 are formed symmetrically with respect to the Y direction. A second filament 4 is fixed to the inclined surface 32 on the other side in the Y direction. The second filament 4 supports the tip portion 5 from the other side in the Y direction. In other words, for example, the tip portion 5 may be fixed to the top portions 41 of the first filament 4 and the second filament 4, and the tip portion 5 may be supported so as to be sandwiched between these top portions 41 in the Y direction.

[0031] 1...emitter, 2...insulator, 3...terminal, 4...filament, 5...tip portion, 32...inclined surface

Claims

1. An emitter comprising: an insulator; a pair of terminals extending along a first direction and fixed to the insulator so as to face each other in a second direction perpendicular to the first direction; a filament fixed to the pair of terminals; and a tip portion formed of an electron emitting material and fixed to the filament, each of the pair of terminals having an inclined surface on one side in a third direction perpendicular to the first and second directions, the inclined surface being inclined with respect to the first direction toward the other side in the third direction as it moves away from the insulator, and the filament being fixed to the pair of terminals at the inclined surface.

2. The emitter according to claim 1, wherein in each of said pair of terminals, said inclined surface does not protrude from an outer surface of said terminal when viewed from said first direction.

3. The emitter according to claim 1 or 2, wherein in each of said pair of terminals, said inclined surface is continuous with an outer surface of said terminal.

4. An emitter as claimed in claim 1 or 2, wherein in each of said pair of terminals, said inclined surface does not reach an end of said terminal opposite said insulator.