TECHNICAL FIELD
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One aspect of the present disclosure relates to an emitter.
BACKGROUND
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Patent Document 1 describes an emitter provided with an insulator, a pair of terminals fixed to the insulator, a filament fixed to the pair of terminals, and a chip part fixed to the filament. In this emitter, the chip part is heated by passing an electric current through the filament via the terminals, and an electron beam is emitted from the chip part.
CITATION LIST
PATENT LITERATURE
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Patent Document 1:
JP 4789122 B2
SUMMARY OF INVENTION
TECHNICAL PROBLEM
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In the emitter described above, it is required to position the chip part 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 chip part.
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Therefore, an object of one aspect of the present disclosure is to provide an emitter in which a chip part is fixed with high accuracy and stability.
SOLUTION TO PROBLEM
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An emitter according to one aspect of the present disclosure is [1] "an emitter provided with: 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, wherein each of the pair of terminals has an inclined surface that is on one side in a third direction perpendicular to the first direction and the second direction and that is inclined with respect to the first direction so as to slope toward the other side in the third direction as it gets farther from the insulator, and the filament is fixed to the pair of terminals at the inclined surface thereof."
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In this emitter, each of the pair of terminals has an inclined surface that is on one side in the third direction and that is inclined with respect to the first direction so as to slope toward the other side in the third direction as it gets farther from the insulator, and the filament is fixed to the pair of terminals at the inclined surfaces. 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 accuracy. Fixing the filament with high accuracy results in highly accurate fixation of the chip part. In addition, because the filament is fixed to the inclined surface, the filament is less likely to move after fixation, allowing the filament and the chip part 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 terminals. As described above, in this emitter, the chip part can be fixed with high accuracy and stability.
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An emitter according to one aspect of the present disclosure may be [2] "the emitter according to [1], wherein, 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 out a portion of the terminal, making it easy to form the inclined surface.
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An emitter according to one aspect of the present disclosure may be [3] "the emitter according to [1] or [2], wherein, in each of the pair of terminals, the inclined surface 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 part formed in the terminal.
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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 suppress sharp portions (e.g., corner parts) from being formed around the chip part, and the emitter can be operated stably. In addition, it is possible to ensure a large area for the end surface of the terminal opposite the insulator, which, when the end surface is to be abutted against another member and positioned, makes it easy to perform this operation.
EFFECTS OF THE INVENTION
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According to one aspect of the present disclosure, it is possible to provide an emitter in which a chip part is fixed accurately and stably.
BRIEF DESCRIPTION OF DRAWINGS
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- FIG. 1 is a front view of an emitter according to an embodiment.
- FIG. 2 is a side view of the emitter.
DESCRIPTION OF EMBODIMENTS
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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 numbers, and redundant descriptions will be omitted.
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As shown in FIG. 1, the emitter 1 includes an insulator 2, a pair of terminals 3, a filament 4, and a chip part 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 an electron microscope, a semiconductor manufacturing device, an inspection device, or a processing device. In the emitter 1, the chip part 5 is heated by passing an electric current through the filament 4 via the pair of terminals 3, and an electron beam is emitted from the tip of the chip part 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.
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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 terminals 3 penetrate the insulator 2 along the Z direction and are fixed to the insulator 2 at their middle portion. The terminal 3 has a protrusion part 31 that protrudes from the insulator 2 to one side in the Z direction (the upper side in FIGS. 1 and 2). The pair of terminals 3 face each other with a gap in the X direction.
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An inclined surface 32 is formed on the protrusion part 31 of each terminal 3. The inclined surface 32 is formed on one side of the protrusion part 31 in the Y direction (the front side of the page in FIG. 1) (the left side in FIG. 2). The inclined surface 32 is inclined with respect to the Z direction so as to slope toward the other side in the Y direction (the farther back of the page in FIG. 1) (the right side in FIG.2) as it gets farther from the insulator 2 (the closer it is to one side in the Z direction). The inclined surface 32 is, for example, an inclined flat surface.
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The inclined surface 32 is formed in the middle of the protrusion part 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. In addition, the inclined surface 32 is continuous with the outer surface of the terminal 3.
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The position and inclination angle of the inclined surface 32 are set so that the chip part 5 is located 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 chip part 5 overlaps the middle 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.
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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 part 41 and a pair of extension parts 42 that extend from the apex part 41 toward both ends. The apex part 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 parts 42 extend straight. The filament 4 is fixed to the protrusion parts 31 of each terminal 3 at the extension parts 42. The extension parts 42 are joined to the protrusion parts 31 by, for example, spot welding.
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More specifically, in this example, the extension parts 42 are fixed to the terminals 3 at the inclined surfaces 32. The extension parts 42 are fixed to the inclined surfaces 32 by welding while being aligned with the inclined surfaces 32. As a result, the inclination angle of the extension parts 42 is determined by the inclined surfaces 32, and the extension parts 42 are inclined with respect to the Z direction so as to slope toward the other side in Y direction (right side in FIG. 2) as they slope toward one side in the Z direction (upper side in FIG. 2).
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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 formed from 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 microstructural stabilization.
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The chip part 5 is fixed to the apex part 41 of the filament 4. The chip part 5 is formed, for example, in a rod shape from an electron emission material. Examples of materials for the chip part 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 and cerium. In this example, the chip part 5 is fixed so as to extend along the Z direction. As described above, in this example, as shown in FIG. 2, the chip part 5 is positioned so as to overlap the middle of the terminal 3 when viewed from the X direction.
[Functions and Effects]
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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 page in FIG. 1 ) (the left side in FIG. 2 ) that is inclined with respect to the Z direction (first direction) so as to slope toward the other side in the Y direction as it gets farther from the insulator 2. The filament 4 is fixed to the pair of terminals 3 at the inclined surfaces 32 thereof. 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 accuracy. By fixing the filament 4 with high accuracy, the chip part 5 can be fixed with high accuracy. In addition, 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 chip part 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 chip part 5 can be fixed with high accuracy and stability.
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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. As a result, this allows the inclined surface 32 to be formed, for example, by cutting out a portion of the terminal 3, making it easy to form the inclined surface 32.
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In each terminal 3, the inclined surface 32 is continuous with the outer surface of the terminal 3. As a result, it is easy to fix the filament 4 to the inclined surface 32 compared with, for example, a case in which the inclined surface 32 is formed by the bottom surface of a groove part formed in the terminal 3.
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In each terminal 3, the inclined surface 32 does not reach the end of the terminal 3 opposite the insulator 2. As a result, it is possible to suppress sharp portions (e.g., corner parts) from being formed around the chip part 5, and the emitter 1 can be operated stably. In addition, a large area can be secured for the end surface of the terminal 3 opposite the insulator 2, and when the end surface is to be abutted against another member for positioning, this operation can be easily performed.
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In the emitter 1, the extension parts 42 of the filament 4, which extend from the apex part 41 (the parts fixed to the chip part 5) to the terminal 3, are formed straight. In other words, no bend parts are formed in the extension parts 42. As a result, 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 an electric current during operation of the emitter 1. In addition, residual stress is less likely to occur in the extension parts 42, making it possible to stably fix the filament 4 and the chip part 5.
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The present disclosure is not limited to the above-described embodiment and modified example. For example, the materials and shapes of the components are not limited to those described above, and various materials and shapes can be adopted.
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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 the protrusion part 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 part may be formed in the terminal 3, and the inclined surface 32 may be formed by the bottom surface of the groove part. In this case, the side surface of the groove part 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.
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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 page in FIG. 1) (the right side in FIG. 2) of the protrusion part 31 of each terminal 3. This inclined surface 32 is inclined with respect to the Z direction so as to slope toward one side in the Y direction as it gets farther from the insulator 2. In other words, the terminals 3 are formed symmetrically with respect to the Y direction. Further, 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 chip part 5 from the other side in the Y direction. In other words, for example, the chip part 5 may be fixed to each apex part 41 of the first filament 4 and the second filament 4, and the chip part 5 may be supported so as to be sandwiched between these apex parts 41 in the Y direction.
REFERENCE SIGNS LIST
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- 1 Emitter
- 2 Insulator
- 3 Terminal
- 4 Filament
- 5 Chip part
- 32 Inclined surface