Emitter and electron gun

Abstract

An emission member (10) has a tip (100) that emits charged particles. The emission member (10) has a columnar part (12) and a first flat surface (101). The first flat surface (101) is positioned at the tip (100) of the emission member (10). In addition, an angle ɑ, formed by the first flat surface (101) and an axis (105) extending from the base of the emission member (10) toward the tip thereof is 85° to 90°. Eight linear edges (120) are formed on at least a portion of the side surface of the columnar part (12).

Description

Emitter and electron gun

[0001] This invention relates to an emitter and an electron gun.

[0002] Emitters, which release charged particles such as electrons and ions, are used in microscopes, inspection equipment, processing equipment, and the like.

[0003] Patent Document 1 describes an emitter needle having a spherical tip. It also describes a structure having five facets on the spherical tip.

[0004] Japanese Patent Publication No. 2023-62203

[0005] However, with respect to the emitter described in Patent Document 1, there was room to improve the stability of charged particle emission from the tip.

[0006] The present invention provides a technique for stably generating sufficient charged particle emission from the tip of the emitter's emission member.

[0007] According to one embodiment of the present invention, the following emitter and electron gun are provided.

[0008] 1. An emitter comprising a discharge member having a tip for emitting charged particles, wherein the discharge member has a columnar portion and a first plane located at the tip, the angle between the first plane and the axis extending from the base of the discharge member to the tip being 85° or more and 90° or less, and eight straight edges are formed on at least a part of the side surface of the columnar portion. 2. An emitter according to 1, wherein the first plane is a quadrilateral or a rounded quadrilateral when viewed with the line of sight in a direction parallel to the axis. 3. An emitter according to 1 or 2, wherein, when the distance between two adjacent edges of the eight edges in a direction perpendicular to the axis is defined as the inter-edge distance, the maximum value of the inter-edge distance is 1.2 times or less the minimum value of the inter-edge distance. 4. From 1 to 3. An emitter according to any one of the above, wherein when viewed with the direction parallel to the axis as the line of sight, the angles of the eight edges are all 130° or more and 140° or less. 5. An emitter according to any one of the above 1 to 4, wherein the area of ​​the first plane is 10,000 nm ２The emitter is as described above. 6. An emitter according to any one of 1 to 5, wherein the width of the base end of the columnar portion is 1.0 times or more and 1.2 times or less the width of the tip end of the columnar portion. 7. An emitter according to any one of 1 to 6, wherein the length of the columnar portion in the direction parallel to the axis is 0.5 μm or more. 8. An emitter according to any one of 1 to 7, wherein the thickness of the emission member between the columnar portion and the first plane tapers toward the tip. 9. An emitter according to any one of 1 to 8, wherein the emission member has a cone portion on the base side of the columnar portion that tapers toward the tip. 10. An emitter according to any one of 1 to 9, wherein the emission member contains a tungsten single crystal. 11. 10. An emitter as described in [reference], wherein the angle between the first plane and any of the (100), (310), (110), and (111) planes of tungsten is 5° or less. 12. An emitter as described in any one of [references] from 1 to 11, wherein it is an electron emitter. 13. An emitter as described in any one of [references] from 1 to 12, wherein it is a thermal field emission emitter. 14. An electron gun comprising an emitter as described in any one of [references] from 1 to 13.

[0009] According to the present invention, a technology can be provided for efficiently extracting charged particles from the tip of the emitter's emission member.

[0010] This is a cross-sectional view illustrating the configuration of an emitter according to an embodiment. This is a diagram illustrating the structure of an emission member according to an embodiment. This is a diagram illustrating an enlarged view of the structure of the tip and vicinity of the tip of the emission member. This is a diagram illustrating an even more enlarged view of the structure of the tip and vicinity of the tip of the emission member. This is a diagram illustrating the columnar portion and the first plane as seen from the tip side. This is a diagram illustrating the relationship between the base, the first terminal, and the second terminal as seen with the +z direction as the line of sight. This is a diagram showing a modified example of the emission member according to an embodiment. This is a diagram illustrating the configuration of an electron gun according to an embodiment.

[0011] Embodiments of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted as appropriate.

[0012] Figure 1 is a cross-sectional view illustrating the configuration of the emitter 50 according to this embodiment. Figure 2 is a diagram illustrating the structure of the discharge member 10 according to this embodiment. Figure 3 is a magnified view illustrating the structure of the tip 100 and the vicinity of the tip 100 of the discharge member 10. Figure 4 is a further magnified view illustrating the structure of the tip 100 and the vicinity of the tip 100 of the discharge member 10. Figure 5 is a diagram illustrating the columnar portion 12 and the first plane 101 as seen from the tip 100 side.

[0013] The emitter 50 according to this embodiment includes an emission member 10. The emission member 10 has a tip 100 that emits charged particles. The emission member 10 has a columnar portion 12 and a first plane 101. The first plane 101 is located at the tip 100 of the emission member 10. Furthermore, the angle α between the first plane 101 and the axis 105 extending from the base to the tip of the emission member 10 is 85° or more and 90° or less. At least a portion of the side surface of the columnar portion 12 has eight straight edges 120 formed thereon. This will be explained in detail below.

[0014] In the example shown in Figure 1, the emitter 50 further comprises a suppressor 20, a filament 30, a base 40, a first terminal 41, a second terminal 42, and a diffusion source (reservoir) 110.

[0015] In all figures, the x, y, and z axes are mutually orthogonal triaxial axes. Charged particles are emitted from the tip 100 of the emission member 10 in the +z direction. Figure 6 illustrates the relationship between the base 40, the first terminal 41, and the second terminal 42 when viewed with the +z direction as the line of sight. The first terminal 41 and the second terminal 42 are aligned in the y-axis direction.

[0016] In the discharge member 10, the side opposite to the tip 100 is called the root side. In the example shown in this figure, the axis 105 is parallel to the z-axis. The axis 105 can be said to be a straight line passing through the centroid of the first reference cross-section of the discharge member 10 and the centroid of the second reference cross-section of the discharge member 10. Here, the first reference cross-section is the cross-section of the discharge member 10 at a position 1 μm from the tip 100 toward the root. The second reference cross-section is the cross-section of the discharge member 10 at a position 2 μm from the tip 100 toward the root. Note that the cross-section can be taken at multiple angles, but the first and second reference cross-sections are the cross-sections at the angles that result in the smallest cross-sectional area.

[0017] In the emission member 10, "thickness" corresponds to the area of ​​the cross-section perpendicular to the axis 105. In the emission member 10, "length" means the length in the direction parallel to the axis 105 (i.e., the length in the z-axis direction). In the emission member 10, "width" means the width in the direction perpendicular to the axis 105 (i.e., the length in the y-axis direction) of the contour of the emission member 10 as identified by observation with an electron microscope. The contour of the emission member 10 can be identified, for example, using an image obtained by imaging the emission member 10 with an electron microscope, with the line of sight parallel to the x-axis.

[0018] Returning to Figure 1, the configuration of the emitter 50 will be explained in detail.

[0019] The emitter 50 is, for example, an electron emitter that emits electrons as charged particles. However, the emitter 50 may also be an emitter that emits ions as charged particles.

[0020] In the example shown in Figure 1, the emitter 50 is a thermal field emitter (TFE). In other words, the emitter 50 can also be described as a Schottky emitter. In this case, the emitter 50 emits electrons by heating the emission member 10 and applying an electric field. However, the emitter 50 is not limited to a thermal field emitter, and may also be a cold field emitter (CFE).

[0021] The suppressor 20 is made of metal and functions as an electrode. The base 40, part of the first terminal 41, part of the second terminal 42, the filament 30, the diffusion source 110, and part of the emission member 10 are located inside the suppressor 20. The suppressor 20 can be used to suppress the emission of charged particles from the sides of the emission member 10, the filament 30, etc. The suppressor 20 has a through hole 201. Examples of the cross-sectional shape of the through hole 201 and the shape of the opening of the through hole 201 include circles, ellipses, polygons, etc. Examples of polygons include triangles, quadrilaterals, pentagons, hexagons, and octagons. The emission member 10 penetrates the through hole 201 of the suppressor 20. That is, the emission member 10 extends from one opening to the other opening in the through hole 201 of the suppressor 20.

[0022] The emission member 10 is fixed to the filament 30. The emission member 10 may also be fixed to the filament 30 via a conductive member. The filament 30 can be used to heat the emission member 10. The emitter 50 may have a single filament 30 or a plurality of filaments 30. The constituent material of the filament 30 can be a material that is heat resistant and conductive. Examples of constituent elements of the filament 30 include tungsten, rhenium, molybdenum, platinum, aluminum, silicon, potassium, etc. The filament 30 may be a tungsten filament, or a tungsten-rhenium (tungsten-rhenium alloy) filament. The diameter of the filament 30 can be, for example, 1 μm to 500 μm, from the viewpoint of easily securing the strength necessary to support the emission member 10, or from the viewpoint of easily increasing the resistance value of the filament 30 and suppressing power consumption.

[0023] The base 40 is made of an insulating material such as resin or ceramic. The first terminal 41 and the second terminal 42 constitute a terminal pair. The first terminal 41 and the second terminal 42 penetrate the base 40 while being separated from each other. In the example of FIG. 1, one end of the filament 30 is connected to the first terminal 41, and the other end of the filament 30 is connected to the second terminal 42. By connecting a power source between the first terminal 41 and the second terminal 42 and passing an electric current through the first terminal 41, the filament 30, and the second terminal 42, the filament 30 is heated, and further, the emission member 10 is heated. The distance between the first terminal 41 and the second terminal 42 in the y-axis direction is preferably 0.1 mm or more from the viewpoint of suppressing inter-terminal discharge, and preferably 10 mm or less from the viewpoint of facilitating miniaturization of the emitter 50. The base 40 is fixed to the suppressor 20.

[0024] The diffusion source 110 is in contact with the emission member 10. The diffusion source 110 may be disposed on the outer periphery of the emission member 10 between the tip of the emission member 10 and the filament 30, or may be disposed on the outer periphery of the central portion of the emission member 10 in the z-axis direction. The constituent material of the diffusion source 110 is not particularly limited, and examples thereof include zirconium oxide (for example, ZrO), calcium oxide (for example, CaO), and the like. By the emitter 50 including the diffusion source 110, when the emission member 10 is heated, the tip 100 of the emission member 10 is covered with the constituent material of the diffusion source 110. By doing so, the work function of the emission surface of the tip 100 can be lowered. Note that the emitter 50 may not include the diffusion source 110.

[0025] Referring to FIGS. 2 to 5, the emission member 10 will be described in detail. As a whole, the emission member 10 has a columnar shape extending in a direction parallel to the axis 105. The shape of the cross section of the emission member 10 perpendicular to the axis 105 may be uniform or non-uniform. The shape of the cross section of the emission member 10 perpendicular to the axis 105 at at least any position thereof may be circular or elliptical, or may be a polygon such as a triangle, a quadrilateral, a pentagon, a hexagon, or an octagon.

[0026] The length of the emission member 10 may be 100 μm or more, 500 μm or more, or 1000 μm or more from the viewpoints of handling property, ease of passing the emission member 10 through the through-hole 201 of the suppressor 20, and design property, etc. The length of the emission member 10 may be 5000 μm or less, 4000 μm or less, or 3000 μm or less from the viewpoints of easily suppressing the inclination of the emission member 10 with respect to the filament 30 or easily suppressing the displacement of the emission member 10 during heating of the filament 30.

[0027] The emission member 10 can contain one or more selected from the group consisting of tungsten, iridium, and lanthanoids. Examples of lanthanoids include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, etc. The emission member 10 can contain at least any one of borides containing tungsten and lanthanoids, CeB ６ , HfC, and compounds containing iridium and lanthanoids as constituent materials. In particular, the emission member 10 can contain at least any one of a single crystal of tungsten, a single crystal of LaB ６ , a single crystal of CeB ６ , a single crystal of HfC, IrCe compounds, and IrLa compounds as constituent materials. Examples of IrCe compounds include Ir ２ Ce, Ir ３ Ce, Ir ７ Ce ２ , Ir ５ Ce, etc. Among them, from the viewpoint that it has a high melting point and is advantageous for high-temperature operation, it is preferable that the emission member 10 contains a single crystal of tungsten. The constituent material of the emission member 10 may be used alone or in combination of two or more. The melting point of the emission member 10 is preferably 2000 °C or more.

[0028] The emission member 10 may further contain at least one of zirconium oxide (e.g., ZrO) and calcium oxide (e.g., CaO). As described above, when the emitter 50 is equipped with a diffusion source 110, when the emission member 10 is heated, the tip 100 of the emission member 10 is covered with the constituent material of the diffusion source 110, and a coating is formed. In this case, an emission member 10 is obtained having a coating containing at least one of zirconium oxide (e.g., ZrO) and calcium oxide (e.g., CaO).

[0029] As described above, the discharge member 10 has a columnar portion 12 and a first plane 101. The first plane 101 is located at the tip 100 of the discharge member 10. Furthermore, the angle α between the first plane 101 and the axis 105 extending from the base to the tip of the discharge member 10 is 85° or more and 90° or less. In addition, eight straight edges 120 are formed on at least a portion of the side surface of the columnar portion 12.

[0030] According to the emitter 50 of this embodiment, the emission member 10 has a first plane 101, which lowers the work function of the emission surface and makes it easier to obtain sufficient emission of charged particles. Furthermore, since eight linear edges 120 are formed on at least a part of the side surface of the columnar portion 12, the evaporation rate of constituent atoms can be kept lower compared to when the columnar portion is cylindrical, i.e., when the side surface consists of a high-index plane. In addition, the strength of the columnar portion 12 is improved, so that changes in shape due to heating and ion impact during use can be suppressed. (Ion impact is a phenomenon in which, for example, gas in a vacuum is positively ionized by electron emission, is attracted to the tip surface of the emission member by an electric field, and collides with it.) As a result, the state of the tip 100 and the vicinity of the tip 100 of the emission member 10 becomes stable. Consequently, sufficient emission of charged particles can be stably generated from the tip.

[0031] The angle α between the first plane 101 and the axis 105 extending from the base to the tip of the emission member 10 is between 85° and 90°. That is, the first plane 101 is a plane approximately perpendicular to the axis 105. Note that the angle between a plane and an axis refers to the smallest angle formed by the plane and the axis. That is, the angle between a plane and an axis is expressed as a value between 0° and 90°. The first plane 101 can be an emission surface that emits charged particles. By having the first plane 101 at the tip 100, the work function of the emission surface can be lowered.

[0032] When the emission member 10 contains a tungsten single crystal, from the viewpoint of lowering the work function of the emission surface, it is preferable that the first plane 101 is a plane that is approximately parallel to any of the (100), (310), (110), and (111) planes of the tungsten single crystal. That is, it is preferable that the angle between the first plane 101 and any of the (100), (310), (110), and (111) planes of tungsten is 5° or less. However, the first plane 101 may be a plane that is approximately parallel to the crystal plane of another crystal.

[0033] The work function of the emission surface at the tip 100 is preferably 4.6 eV or less, and more preferably 2.7 eV or less.

[0034] The first plane 101 is preferably a quadrilateral or a rounded quadrilateral when viewed with the line of sight parallel to the axis 105. Alternatively, the first plane 101 may be circular. From the viewpoint of increasing the extraction efficiency of charged particles from the tip 100, the area of ​​the first plane 101 is 10,000 nm. ２ Preferably, the above, and 12000 nm ２ It is more preferable that the above conditions are met. It is preferable that the axis 105 passes through the first plane 101, and more preferably that it passes through the center (i.e., the centroid) of the first plane 101.

[0035] Eight straight edges 120 are formed on at least a portion of the side surface of the columnar portion 12. For example, the columnar portion 12 is approximately an octagonal prism. The straight edges 120 will also be referred to as "straight edges 120" below. As illustrated in Figure 3, at least one of the straight edges 120 and the straight edge 120 located next to it in the circumferential direction may be connected at their ends by a curved edge. In that case, "straight edge 120" refers to the straight portion of the entire edge. Note that each of the straight edges 120 may be independent and not connected to other straight edges 120, as illustrated in Figure 7. Note that the circumferential direction is the circumferential direction with respect to the axis 105.

[0036] The straight edge 120 may have a slight undulation. For example, it is preferable that the straightness of the straight edge 120 is 100 nm or less. The straightness of the straight edge 120 being 100 nm or less means that the straight edge 120 lies between two parallel lines that are separated by 100 nm and extend in at least one direction.

[0037] Furthermore, from the viewpoint of reducing the emission of charged particles from the sides, it is preferable that the columnar portion 12 is close to a regular octagonal prism. For example, among the eight straight edges 120, the distance between two adjacent straight edges 120 in the direction perpendicular to the axis 105 is the inter-edge distance d. ｅ In this case, the distance between edges d ｅ The maximum value is the distance d between edges. ｅ It is preferable that it is 1.2 times or less the minimum value. When viewed in the direction parallel to the axis 105 as the line of sight, the angle β of the eight straight edges 120 is preferably 130° or more and 140° or less, and preferably 130° or more and 135° or less. The corners of the straight edges 120 may be rounded. That is, when viewed in the direction parallel to the axis 105 as the line of sight, the corners of the straight edges 120 may be rounded. However, in that case, when viewed in the direction parallel to the axis 105 as the line of sight, it is preferable that each of the eight straight edges 120 has a radius of curvature of 100 nm or less.

[0038] It is preferable that the eight straight edges 120 are approximately parallel to each other. It is also preferable that each of the eight straight edges 120 is approximately parallel to the axis 105. It is preferable that the angle between each of the eight straight edges 120 and the axis 105 is between 0° and 5°.

[0039] Preferably, at least one cross-section of the columnar portion 12 perpendicular to the axis 105 intersects with all eight straight edges 120. Preferably, at least one cross-section of the columnar portion 12 perpendicular to the axis 105 is octagonal. The eight straight edges 120 are spaced apart in the circumferential direction with respect to the axis 105. The surfaces between adjacent straight edges 120 are preferably flat, but may include curved surfaces. The distance d between adjacent straight edges 120 is... ｅ The length L of either of the two straight edges 120 is... ｅ It is preferable that it be shorter than this. In Figure 3, an example is shown in which the straight edge 120 extends over the entire length of the columnar portion 12 in the direction parallel to the axis 105 (z-axis direction), but the straight edge 120 may extend only to a portion of the columnar portion 12 in the direction parallel to the axis 105.

[0040] The planes between adjacent straight edges 120 preferably include the fundamental index planes of the crystal contained in the emission member 10. Examples of fundamental index planes of tungsten crystals include the (100) plane, the (310) plane, the (110) plane, and the (111) plane.

[0041] The thickness of the columnar portion 12 is preferably approximately uniform in the direction parallel to the axis 105. For example, the width d of the base end of the columnar portion 12. ２ｒ The width d of the end of the columnar portion 12 on the tip 100 side is ２ｔ It is preferable that it is 1.0 times or more and 1.2 times or less. However, the thickness of the columnar portion 12 may be tapered towards the tip. |d ２ｒ -d ２ｔ The value calculated using | is preferably 100 nm or less, and more preferably 50 nm or less.

[0042] In the example shown in Figure 3, the thickness of the discharge member 10 tapers towards the tip 100 between the columnar portion 12 and the first plane 101. The portion located between the columnar portion 12 and the first plane 101, which tapers towards the tip 100, is called the tip portion 11. The very front of the discharge member 10 may be composed of the tip portion 11. That is, the surface of the tip portion 11 may include a discharge surface that emits charged particles. The outer surface of the tip portion 11 may include a plurality of facets, that is, the surface of the tip portion 11 may include a plurality of planes. However, the surface of the tip portion 11 may include a curved surface.

[0043] Furthermore, in the example shown in Figure 3, the discharge member 10 has a cone-shaped portion 13 that tapers towards the tip 100, located closer to the base than the columnar portion 12. That is, the discharge member 10 comprises, in order from the tip 100 side, a tip portion 11, a columnar portion 12, and a cone-shaped portion 13.

[0044] In the emission member 10 according to this embodiment, the presence of a columnar portion 12 between the tip portion 11 and the cone portion 13 suppresses the influence of the cone portion 13 on the electric field near the tip 100. In other words, it is possible to reduce the amount of charged particles emitted from areas other than the tip 100. Consequently, the beam diameter can be reduced.

[0045] The tip portion 11, the columnar portion 12, and the cone portion 13 are distinct parts. That is, the tip portion 11, the columnar portion 12, and the cone portion 13 do not overlap with each other. In the example in Figure 2, the discharge member 10 has an additional portion with a nearly uniform thickness closer to the base than the cone portion 13.

[0046] From the standpoint of sharpening, it is preferable that the discharge member 10 does not have a portion that becomes thicker towards the tip 100. However, the discharge member 10 may have a portion that becomes thicker towards the tip 100.

[0047] The length of the cone portion 13 is not particularly limited, but for example, it is between 1 μm and 1000 μm. The distance L between the end of the cone portion 13 on the tip 100 side and the tip 100. ｔ３The diameter is not particularly limited, but for example, it is 1 μm or more and 5 μm or less. In the discharge member 10 according to this embodiment, the columnar portion 12 described above is provided on the tip 100 side of the cone portion 13, so the distance L ｔ３ Even if the thickness is 5 μm or less, the influence of the cone portion 13 on the electric field near the tip 100 is suppressed.

[0048] The rate of change in the thickness of the columnar portion 12 is preferably smaller than the rate of change in the thickness of the cone portion 13. Furthermore, the rate of change in the thickness of the columnar portion 12 is preferably smaller than the rate of change in the thickness of the tip portion 11. For each portion, the rate of change in thickness can be calculated as |"thickness at one end of the portion" - "thickness at the other end of the portion"| / "length of the portion (in the axial direction)". Let the length of the columnar portion 12 be L ２ In this case, the rate of change of the thickness of the columnar portion 12 is the width d. ２ｒ and width d ２ｔ Using |d ２ｒ -d ２ｔ | / L ２ The value calculated using [the formula / method] is also acceptable.

[0049] The length L of the columnar portion 12 in the direction of the axis 105. ２ Preferably, the length L of the columnar portion 12 is 0.6 times or more the minimum width (in the y-axis direction) of the columnar portion 12. From the viewpoint of suppressing the influence of the cone portion 13 on the electric field near the tip 100, the length L of the columnar portion 12 is preferable. ２ The length L of the columnar portion 12 is more preferably 1.0 times or more the minimum width of the columnar portion 12, and even more preferably 1.5 times or more. From the viewpoint of increasing the strength of the release member 10, the length L of the columnar portion 12 is ２ The width of the columnar portion 12 is preferably 6 times or less the width of the release member 10 at the boundary between the tip portion 11 and the columnar portion 12, and more preferably 5 times or less. If the thickness of the columnar portion 12 increases in the direction away from the tip portion 100, the width d at the end of the columnar portion 12 on the tip portion 100 side is also specified. ２ｔ However, this can be said to be the minimum width of the columnar portion 12.

[0050] From the viewpoint of reducing the emission of charged particles from the sides, the length of the columnar portion 12 in the direction parallel to the axis 105 is preferably 0.5 μm or more, and more preferably 1.0 μm or more. On the other hand, from the viewpoint of increasing the strength of the emission member 10, the length of the columnar portion 12 is preferably 2.0 μm or less.

[0051] In the example shown in Figure 3, the tip portion 11 and the columnar portion 12 are adjacent to each other. That is, there is no other part interposed between the tip portion 11 and the columnar portion 12. From the viewpoint of suppressing the influence of the cone portion 13 on the electric field near the tip 100, the length L of the columnar portion 12 is considered. ２ The length of the columnar portion 12 is preferably 0.6 times or more the width of the discharge member 10 at the boundary between the tip portion 11 and the columnar portion 12, and more preferably 1.0 times or more. From the viewpoint of increasing the strength of the discharge member 10, the length L of the columnar portion 12 is ２ The width of the discharge member 10 at the boundary between the tip portion 11 and the columnar portion 12 is preferably 6 times or less, and more preferably 5 times or less. Note that the example in Figure 3 is not limited, and other portions may exist between the tip portion 11 and the columnar portion 12.

[0052] In the example shown in Figure 3, the inclination of the side surface of the cone portion 13 relative to the shaft 105 changes along the contour of the emission member 10 as identified by electron microscopy. That is, the inclination of the side surface of the cone portion 13 relative to the shaft 105 is not uniform in the contour of the emission member 10 as identified by electron microscopy. Specifically, in the base portion 13b of the cone portion 13, the rate of change in thickness is smaller than in the tip portion 13a. In other words, in the contour of the emission member 10 as identified by electron microscopy, the inclination of the side surface of the cone portion 13 relative to the shaft 105 in a part of the base portion is smaller than the inclination of the side surface of the cone portion 13 relative to the shaft 105 in another part of the cone portion 13 on the tip 100 side.

[0053] In the example shown in Figure 3, the columnar portion 12 and the cone portion 13 are adjacent to each other. That is, there is no other part between the columnar portion 12 and the cone portion 13. However, the example is not limited to Figure 3, and other parts may exist between the columnar portion 12 and the cone portion 13.

[0054] Furthermore, in the contour of the emission member 10 as identified by observation with an electron microscope, the boundary between the tip portion 11 and the columnar portion 12 may or may not have an edge. That is, as shown in Figure 3, in the contour of the emission member 10, the boundary between the tip portion 11 and the columnar portion 12 may be a curve. The boundary between the tip portion 11 and the columnar portion 12 may be a curved surface. Also, in the contour of the emission member 10 as identified by observation with an electron microscope, the boundary between the columnar portion 12 and the cone portion 13 may or may not have an edge. That is, in the contour of the emission member 10, the boundary between the columnar portion 12 and the cone portion 13 may be a curve. The boundary between the columnar portion 12 and the cone portion 13 may be a curved surface.

[0055] Figure 7 shows a modified example of the emission member 10 according to this embodiment. In the example of Figure 3, the inclination of the side surface of the cone portion 13 with respect to the axis 105 was not uniform in the contour of the emission member 10 as identified by observation with an electron microscope. In contrast, in the example of Figure 7, the inclination of the side surface of the cone portion 13 with respect to the axis 105 is uniform in the contour of the emission member 10 as identified by observation with an electron microscope. Also, as described above, in the example of Figure 7, each of the straight edges 120 is independent and not connected to any other straight edges 120.

[0056] An example of a method for manufacturing the emission member 10 and the emitter 50 will be described below. However, the method for manufacturing the emission member 10 and the emitter 50 is not limited to this example.

[0057] Prepare a columnar member as a component material for the discharge member 10. Also, prepare a structure combining a base 40, a first terminal 41, a second terminal 42, and a filament 30. When viewed with the line of sight parallel to the x-axis, the columnar member is positioned between the first terminal 41 and the second terminal 42, and the side surface of the base end of the columnar member is welded to the side surface of the bent portion of the filament 30 to connect them. If two filaments 30 are used, the columnar member can be gripped by the bent portions of the two filaments 30.

[0058] Next, the tip of the columnar member is sharpened by electropolishing. Then, a diffusion source 110 is formed on the outer circumference of the central part of the discharge member 10 in the direction of charged particle discharge. After that, the tip portion 11, columnar portion 12, and cone portion 13 are formed by heat treatment in an oxygen atmosphere, and the discharge member 10 fixed to the filament 30 is obtained. The conditions for this heat treatment are a temperature of 1500K to 2000K and a vacuum of 1 × 10⁻¹⁰ －４ Pa or less 1×10 －８ Pa or higher, oxygen intake rate 1 x 10⁻⁶ －５ Pa or less 1×10 －９ The pressure can be Pa or higher, and the duration can be between 2 hours and 200 hours. Furthermore, the chip temperature of the discharge member 10 should be 1600K or higher, and the voltage V should be 0.3kV or higher. ｅｘ (See Figure 8) By applying the ion beam and allowing charged particles to be emitted from the emission member 10 for at least one hour, eight straight edges are more easily formed on at least a portion of the side surface of the columnar portion 12. However, the example is not limited to this, and for example, the tip portion 11, the columnar portion 12, and the cone portion 13 may be formed by processing with a focused ion beam. Then, the suppressor 20 is fixed to the base 40 with the tip portion 100 passing through the through hole 201 of the suppressor 20.

[0059] In addition, during the heat treatment under the oxygen atmosphere described above, the constituent material of the diffusion source 110 may diffuse to the tip 100 of the discharge member 10, and a coating may be formed.

[0060] Figure 8 is a diagram illustrating the configuration of the electron gun 60 according to this embodiment. The electron gun 60 according to this embodiment includes an emitter 50 according to this embodiment. In the example in Figure 8, the electron gun 60 further includes an extraction electrode 62 facing the suppressor 20 of the emitter 50. The electron gun 60 according to this embodiment can be used as a Schottky electron gun, for example. The electron gun 60 can be used in combination with power supplies 64, 65, and 66. However, the electron gun 60 does not have to include these power supplies.

[0061] The extraction electrode 62 can be used to provide an electric field for emitting electrons from the emission member 10. The extraction electrode 62 may have a through hole 620 through which electrons emitted from the emission member 10 pass. When electrons are emitted, the extraction electrode 62 may have a positive potential relative to the suppressor 20.

[0062] A positive voltage V is applied to the lead electrode 62, with the potential of the first terminal 41 as the reference. ｅｘ The power supply 64 may be connected to the lead electrode 62 to apply the current.

[0063] Power supply 65 is a power source for heating the discharge member 10. Current I from power supply 65 ｆ The power supply 65 can be connected to the first terminal 41 and the second terminal 42 so that current flows through the filament 30. While current is flowing through the filament 30, the first terminal 41 has a positive potential relative to the second terminal 42.

[0064] Power supply 66 supplies voltage V to suppressor 20. ｂ This is a power supply for applying a negative voltage V to the suppressor 20, with the potential of the first terminal 41 as the reference. ｂ A power supply 66 may be connected to the suppressor 20 to apply the voltage.

[0065] The electron gun 60 according to this embodiment may further include an accelerating electrode (not shown) facing the extraction electrode 62 at a position opposite to the suppressor 20 with respect to the extraction electrode 62. In this case, the extraction electrode 62 is positioned between the suppressor 20 and the accelerating electrode. The accelerating electrode can be used to accelerate electrons emitted from the emission member 10. The accelerating electrode may have a through hole through which electrons emitted from the emission member 10 pass. When electrons are emitted, the accelerating electrode may have a positive potential with respect to the potential of the extraction electrode 62.

[0066] A power supply is connected to the accelerating electrode to apply a voltage to it, and a positive voltage can be output to the accelerating electrode with the potential of the extraction electrode 62 as a reference.

[0067] The electron gun 60 according to this embodiment can be used in an electron beam apparatus. The electron beam apparatus may be equipped with the electron gun according to this embodiment. Examples of electron beam apparatuses include X-ray generators, electron microscopes, semiconductor manufacturing equipment, analytical equipment (inspection equipment: e.g., electron probe microanalyzers), processing equipment (e.g., electron beam deposition equipment), etc.

[0068] Next, the operation and effects of this embodiment will be described. According to this embodiment, the emission member 10 has a columnar portion 12 and a first plane 101. At least a portion of the side surface of the columnar portion 12 has eight straight edges 120 formed thereon. Therefore, a sufficient amount of charged particles can be stably emitted from the tip 100 of the emission member 10 of the emitter.

[0069] The embodiments of the present invention have been described above with reference to the drawings, but these are merely examples of the present invention, and various other configurations can be adopted. For example, the execution order of the steps performed in the embodiments is not limited to the order in which they are described. In the embodiments, the order of the steps can be changed to the extent that it does not impede the content. Furthermore, the embodiments and multiple modifications described above can be combined to the extent that they do not conflict in content.

[0070] This application claims priority based on Japanese Patent Application No. 2024-174108, filed on 3 October 2024, and incorporates all of its disclosures herein.

[0071] 10 Emission member 11 Tip 12 Columnar part 13 Cone part 20 Suppressor 30 Filament 40 Base 41 First terminal 42 Second terminal 50 Emitter 60 Electron gun 62 Lead electrode 64 Power supply 65 Power supply 66 Power supply 100 Tip 101 First plane 105 Axis 110 Diffusion source 120 Straight edge 201 Through hole 620 Through hole

Claims

1. An emitter comprising a discharge member having a tip for emitting charged particles, wherein the discharge member has a columnar portion and a first plane located at the tip, the angle between the plane and the axis extending from the base of the discharge member to the tip being 85° or more and 90° or less, and at least a portion of the side surface of the columnar portion has eight straight edges formed thereon.

2. An emitter according to claim 1, wherein the first plane is a quadrilateral or a rounded quadrilateral when viewed with the direction parallel to the axis as the line of sight.

3. An emitter according to claim 1 or 2, wherein, when the distance between two adjacent edges among the eight edges in a direction perpendicular to the axis is defined as the inter-edge distance, the maximum value of the inter-edge distance is 1.2 times or less the minimum value of the inter-edge distance.

4. An emitter according to any one of claims 1 to 3, wherein, when viewed in a direction parallel to the axis as the line of sight, the angles of the eight edges are all 130° or more and 140° or less.

5. In the emitter according to any one of claims 1 to 4, the area of ​​the first plane is 10,000 nm ２ That's all, Emitter.

6. An emitter according to any one of claims 1 to 5, wherein the width of the base end of the columnar portion is 1.0 times or more and 1.2 times or less the width of the tip end of the columnar portion.

7. An emitter according to any one of claims 1 to 6, wherein the length of the columnar portion in the direction parallel to the axis is 0.5 μm or more.

8. An emitter according to any one of claims 1 to 7, wherein the thickness of the emission member between the columnar portion and the first plane tapers towards the tip.

9. An emitter according to any one of claims 1 to 8, wherein the emission member has a cone portion that tapers in diameter toward the tip, with the base portion being closer to the columnar portion.

10. An emitter according to any one of claims 1 to 9, wherein the emission member is an emitter containing a single crystal of tungsten.

11. An emitter according to claim 10, wherein the angle between the first plane and any of the (100) plane, (310) plane, (110) plane, and (111) plane of tungsten is 5° or less.

12. An emitter according to any one of claims 1 to 11, wherein the emitter is an electron emitter.

13. An emitter according to any one of claims 1 to 12, wherein the emitter is a thermal field emission emitter.

14. An electron gun comprising the emitter according to any one of claims 1 to 13.

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