Electron gun component, electron gun, and electron beam device

Abstract

This electron gun component comprises: an electron emission member that has a tip from which electrons are emitted as a result of heating; and a suppressor electrode that has an opening. The electron emission member is inserted into the opening. Following heating of the electron emission member from 298K to 1800K, when a region occupied by the electron emission member is observed on an opening surface B of said opening on the tip side while maintaining the temperature of the electron emission member at 1800K, a distance D1 between a center C11 of said region (region A11) after 1 min once the temperature of the electron emission member reaches 1800K and a center C12 of said region (region A12) after 24 h is 20 μm or less.

Description

Electron gun parts, electron guns, and electron beam devices

[0001] The present disclosure relates to electron gun components, electron guns, electron beam devices, and the like.

[0002] Electron guns are used in electron beam devices such as electron microscopes and semiconductor inspection devices. Electron guns include an electron gun component and an extraction electrode, and the electron gun component includes an electron-emitting member having a tip that emits electrons when heated, and a suppressor electrode having an opening. Various configurations of electron guns have been studied (see, for example, Patent Document 1 listed below).

[0003] Japanese Patent Application Laid-Open No. 2007-250491

[0004] In electron gun components, the position of the electron-emitting member may fluctuate due to heating for electron emission, which may result in electrons being emitted to a position different from the intended irradiation position, making it difficult to achieve sufficient irradiation accuracy.

[0005] An object of one aspect of the present disclosure is to provide an electron gun component that can obtain sufficient irradiation accuracy even when heated for electron emission.Another object of the present disclosure is to provide an electron gun including such an electron gun component.Another object of the present disclosure is to provide an electron beam device including such an electron gun.

[0006] [1] An electron gun component comprising: an electron-emitting member having a tip that emits electrons when heated; and a suppressor electrode having an opening, the electron-emitting member being inserted into the opening, and when the electron-emitting member is heated from 298 K to 1800 K and then the temperature of the electron-emitting member is maintained at 1800 K while observing an area occupied by the electron-emitting member on the opening surface on the tip side of the opening, the distance between the center of the area one minute after the temperature of the electron-emitting member reaches 1800 K and the center of the area 24 hours later is 20 μm or less. [2] The electron gun component according to [1], wherein the distance between the centers of the two farthest points among the centers of five points obtained by repeating the following steps (1) to (3) five times is 20 μm or less.

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[0007] According to one aspect of the present disclosure, it is possible to provide an electron gun component that can obtain sufficient irradiation accuracy even when heated for electron emission. According to another aspect of the present disclosure, it is possible to provide an electron gun including such an electron gun component. According to another aspect of the present disclosure, it is possible to provide an electron beam device including such an electron gun.

[0008] Fig. 1 is an end view schematically showing an example of an electron gun component. Fig. 2 is a view showing an example of an opening surface of a suppressor electrode on the tip side of an electron emitting member. Fig. 3 is a view showing another example of an opening surface of a suppressor electrode on the tip side of an electron emitting member. Fig. 4 is a plan view schematically showing a connection mode of a filament and a terminal.

[0009] A numerical range "A or more" means A and a range exceeding A. A numerical range "A or less" means a range of A and less than A. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range in a certain stage can be arbitrarily combined with the upper limit or lower limit of a numerical range in another stage. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in the examples. "A or B" may include either A or B, or may include both. The materials exemplified in this specification may be used alone or in combination of two or more.

[0010] The electron gun component according to this embodiment includes an electron emitter having a tip that emits electrons when heated, and a suppressor electrode having an opening, the electron emitter being inserted into the opening of the suppressor electrode. In the electron gun component according to this embodiment, after the electron emitter is heated from 298 K to 1800 K, the temperature of the electron emitter is maintained at 1800 K. When a region A occupied by the electron emitter is observed on the opening surface of the suppressor electrode on the tip side of the electron emitter (hereinafter sometimes simply referred to as the "suppressor electrode opening surface"), the distance D1 between the center of region A 1 minute after the temperature of the electron emitter reaches 1800 K and the center of region A 24 hours later is 20 μm or less. The temperature of the electron emitter refers to the temperature of the portion of the electron emitter that is closer to the tip (the tip of the electron emitter) than the opening surface of the suppressor electrode (the same applies to the temperature of the electron emitter hereinafter).

[0011] In the electron gun component according to this embodiment, the distance D1 is 20 μm or less, which prevents the position of the electron emitting member from fluctuating due to heating for electron emission, and therefore electrons can be emitted to the target irradiation position, thereby achieving sufficient irradiation accuracy even when heated for electron emission.

[0012] According to the electron gun component of this embodiment, the position of the electron emitting member is prevented from fluctuating due to heating for electron emission, so that suitable electron emission can be maintained without adjusting the position of the electron emitting member. In this case, when multiple electron emitting members are used, the burden of adjusting the position of each electron emitting member can be reduced. The electron gun component of this embodiment can be used as a Schottky electron gun component.

[0013] The electron gun component according to this embodiment includes an electron-emitting member having a tip that emits electrons when heated. The tip of the electron-emitting member may emit electrons when heated and an electric field is applied. The electrons may be emitted in any direction, such as vertically upward, vertically downward, horizontally, a direction tilted from the vertical, or a direction tilted from the horizontal. The shape of the electron-emitting member is not particularly limited, and the electron-emitting member may be, for example, a columnar member extending in the electron emission direction. Examples of the cross-sectional shape of the electron-emitting member (a cross-section perpendicular to the electron emission direction) include a circle (a perfect circle, an ellipse, etc.) and a polygon (a triangle, a rectangle, a pentagon, a hexagon, etc.). The tip of the electron-emitting member may be flat or sharp (for example, tapered to a point).

[0014] The length of the electron emitting member (length in the electron emission direction) may be within the following ranges. From the viewpoint of easily suppressing the influence of emission noise from locations other than the electron emission location of the electron emitting member, the length of the electron emitting member may be 100 μm or more, 500 μm or more, or 1000 μm or more. From the viewpoint of easily suppressing tilt of the electron emitting member with respect to the filament or easily suppressing displacement of the electron emitting member during heating of the filament, the length of the electron emitting member may be 5000 μm or less, 4000 μm or less, or 3000 μm or less. From these viewpoints, the length of the electron emitting member may be 100 to 5000 μm, 500 to 4000 μm, or 1000 to 3000 μm.

[0015] Examples of constituent elements of the electron-emitting member include tungsten, iridium, lanthanoids, etc. Examples of lanthanoids include lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Examples of constituent materials of the electron-emitting member include tungsten (for example, single crystals of tungsten such as W(100) and W(310)), lanthanoid-containing borides (LaB ６ (e.g., LaB ６ single crystal), CeB ６ (For example, CeB ６ Examples of the IrCe compound include Ir ２ Ce, Ir ３ Ce, Ir ７ Ce ２ , Ir ５ Ce, etc. The constituent materials of the electron-emitting member may be used singly or in combination of two or more.

[0016] The electron-emitting member is inserted into the opening (through-hole) of the suppressor electrode and penetrates the opening of the suppressor electrode, i.e., the electron-emitting member extends from one opening surface of the opening of the suppressor electrode to the other opening surface.

[0017] From the viewpoint of reducing power consumption or miniaturizing the device in which the electron emitting member is mounted, the power supplied to the electron emitting member when the electron emitting member is heated from 298 K to 1800 K (for example, heated at a temperature increase rate of 500 K / min) may be 5.0 W or less, 4.0 W or less, 3.5 W or less, 3.0 W or less, 2.5 W or less, or 2.0 W or less. The power supplied to the electron emitting member can be adjusted by the constituent material of the electron emitting member; the constituent material, length, cross-sectional shape, etc. of the filament described below.

[0018] The electron gun component according to this embodiment includes a suppressor electrode having an opening (through-hole), through which an electron-emitting member is inserted. The suppressor electrode can be used to suppress electron emission from portions of the electron-emitting member other than the tip (for example, the side portions of the electron-emitting member), and can also be used to suppress electron emission from other members such as a filament, which will be described later. Examples of the cross-sectional shape of the opening in the suppressor electrode and the shape of the opening surface of the opening include circles (perfect circles, ellipses, etc.) and polygons (triangles, rectangles, pentagons, hexagons, etc.).

[0019] The electron gun component according to this embodiment may include an electron source having an electron-emitting member and a suppressor electrode. The electron source may include a member other than the electron-emitting member. Examples of the member other than the electron-emitting member include a diffusion source (reservoir), a filament, a support member, and the like.

[0020] The diffusion source is in contact with the electron emitting member. The diffusion source may be disposed on the outer periphery of the electron emitting member between the tip and base ends of the electron emitting member, or on the outer periphery of the central part of the electron emitting member in the electron emission direction. The constituent material of the diffusion source is not particularly limited, and examples thereof include zirconium oxide (e.g., ZrO), calcium oxide (e.g., CaO), etc.

[0021] The filament is connected to the electron-emitting member and may be connected to the electron-emitting member via a conductive member between them. The filament can be used to heat the electron-emitting member. The electron source may have a single filament or multiple filaments. The filament may be made of a heat-resistant and conductive material. Elements constituting the filament include tungsten, rhenium, molybdenum, platinum, aluminum, silicon, potassium, etc. The filament may be a tungsten filament or a tungsten-rhenium (tungsten-rhenium alloy) filament. The diameter of the filament may be 1 to 500 μm, 1 to 200 μm, 1 to 120 μm, 10 to 500 μm, 10 to 200 μm, 10 to 120 μm, 100 to 500 μm, 100 to 200 μm, 100 to 120 μm, 120 to 500 μm, or 120 to 200 μm, from the viewpoint of easily ensuring the strength required to support the electron emitting member or from the viewpoint of easily increasing the resistance value of the filament and suppressing power consumption. The rhenium content of the tungsten rhenium may be 0.1 to 50 mass%, 0.1 to 30 mass%, 0.1 to 10 mass%, 1 to 50 mass%, 1 to 30 mass%, 1 to 10 mass%, 10 to 50 mass%, or 10 to 30 mass%, from the viewpoint of easily ensuring the strength required to support the electron emitting member or from the viewpoint of easily increasing the resistance value of the filament and suppressing power consumption.

[0022] The support member supports the filament. The support member may have an insulating member and a pair of terminals, and the pair of terminals may penetrate the insulating member at a distance from each other. In this case, the filament may be connected to the electron emitting member with one end of the filament connected to one terminal and the other end of the filament connected to the other terminal, or the first filament and the second filament may be connected to the electron emitting member with both ends of the first filament connected to one terminal and both ends of the second filament connected to the other terminal. The inter-terminal distance between the pair of terminals (the distance between the closest portions of the terminals) may be 0.1 to 10 mm, 0.1 to 8 mm, 0.1 to 6 mm, 0.1 to 4 mm, 1 to 10 mm, 1 to 8 mm, 1 to 6 mm, 1 to 4 mm, 2 to 10 mm, 2 to 8 mm, 2 to 6 mm, or 2 to 4 mm, from the viewpoint of easily ensuring a distance that suppresses inter-terminal discharge or easily miniaturizing the electron gun.

[0023] The electron gun component according to this embodiment may include a first power supply for heating (heating by electrical current) the electron emitting member and / or the filament. The first power supply is capable of supplying a current to the electron emitting member for heating the electron emitting member, and is capable of supplying a current to the filament for heating the filament. The first power supply may be electrically connected to the electron emitting member via the filament, may be electrically connected to the electron emitting member via a terminal of the support member and the filament, or may be electrically connected to the filament via a terminal of the support member.

[0024] The electron gun component according to this embodiment may include a second power supply (bias power supply, suppressor power supply) for applying a voltage to the suppressor electrode. The second power supply may be connected to the suppressor electrode and may output a negative voltage with respect to the suppressor electrode.

[0025] 1 is a schematic end view of an example of an electron gun component 100. The electron gun component 100 includes an electron emitting member 10, a diffusion source (reservoir) 20, a filament 30, a support member 40, and a suppressor electrode 50.

[0026] The electron-emitting member 10 is a columnar member extending in the electron emission direction and has a tip 10a that emits electrons when heated. The diffusion source 20 is disposed on the outer periphery of the central portion of the electron-emitting member 10 in the electron emission direction. The filament 30 has a shape obtained by bending a straight filament, and the base end of the electron-emitting member 10 is connected to the bent portion of the filament.

[0027] The support member 40 has an insulating member (insulator) 42 and a pair of linear terminals 44. The pair of terminals 44 penetrate the insulating member 42 at a distance from each other. One end of the filament 30 is connected to one of the pair of terminals 44, and the other end of the filament 30 is connected to the other of the pair of terminals 44. A first power source (not shown) for heating the electron-emitting member 10 is electrically connected to the electron-emitting member 10 via the pair of terminals 44 and the filament 30.

[0028] The suppressor electrode 50 has a cylindrical portion 52, a connecting portion 54, a tapered portion 56, and a tip portion 58. The cylindrical portion 52 is a cylindrical body having an internal space and is connected to the insulating member 42 housed in the internal space via the connecting portion 54 disposed in the internal space. The tapered portion 56 is connected to the end of the cylindrical portion 52 in the electron emission direction. The tapered portion 56 has a diameter that decreases along the electron emission direction. The tip portion 58 is connected to the end of the tapered portion 56 in the electron emission direction. The tip portion 58 is flat, and an opening 50a through which the electron emitting member 10 is inserted is formed in the center of the tip portion 58. The opening 50a has an opening surface 50b as an end (end face) on the tip 10a side of the electron emitting member 10. A second power supply (not shown) for applying a voltage to the suppressor electrode 50 is connected to the suppressor electrode 50.

[0029] In the electron gun component according to this embodiment, after the electron emitter is heated from 298 K to 1800 K (e.g., heated at a temperature rise rate of 500 K / min), the temperature of the electron emitter is maintained at 1800 K. When observing a region A occupied by the electron emitter on the opening surface (opening end) of the suppressor electrode on the tip side of the electron emitter, the distance D1 between the center of region A 1 minute after the temperature of the electron emitter reaches 1800 K and the center of region A 24 hours later is 20 μm or less, from the viewpoint of easily obtaining sufficient irradiation accuracy under heating for electron emission. The distance D1 may be 15 μm or less, 10 μm or less, 8 μm or less, 6 μm or less, 5 μm or less, 3 μm or less, or 2 μm or less, from the viewpoint of easily obtaining sufficient irradiation accuracy under heating for electron emission. The distance D1 may be 0 μm or more, more than 0 μm, 1 μm or more, or 2 μm or more. From these perspectives, the distance D1 may be 0 μm or more and 20 μm or less, 0 μm or more and 10 μm or less, 0 μm or more and 6 μm or less, more than 0 μm and 20 μm or less, more than 0 μm and 10 μm or less, or more than 0 μm and 6 μm or less. The distance D1 can be obtained using an observation image of the aperture surface of the suppressor electrode, as shown in the examples described below. The observation image can be obtained by focusing on the aperture surface of the suppressor electrode from the tip side of the electron emitting member in a direction perpendicular to the aperture surface of the suppressor electrode. An image of the aperture surface can be obtained regardless of the opening direction of the suppressor electrode. Since the thermal expansion of the components of the electron gun component has a significant effect from the time when the temperature of the electron emitting member reaches 1800 K until one minute, the displacement of the electron emitting member due to heating can be appropriately evaluated by targeting the center of region A one minute after the temperature of the electron emitting member reaches 1800 K. If the shape of region A is not a perfect circle, the center of the smallest circumscribing circle of region A is used as the center of region A. The distance D1 can be adjusted by the connection mode of the filament and terminal; the amount of deviation in the left and right length of the filament from the center of the electron gun component; the amount of deviation in the joining position of the electron-emitting member from the center of the filament; the joining angle of the electron-emitting member, etc.

[0030] Fig. 2 is a diagram showing an example of the opening surface of the suppressor electrode on the tip side of the electron emitting member, and is a diagram obtained by observing region A while maintaining the temperature of the electron emitting member at 1800 K. In Fig. 2, region A occupied by the electron emitting member is present on opening surface B of the suppressor electrode. Region A11 and center C11 indicate region A and its center one minute after the temperature of the electron emitting member reaches 1800 K, and region A12 and center C12 indicate region A and its center 24 hours after the temperature of the electron emitting member reaches 1800 K. In this case, the distance between center C11 and center C12 corresponds to distance D1.

[0031] In the electron gun component according to this embodiment, the procedure of the following steps (1) to (3) (in the order of steps (1), (2), and (3)) is repeated five times, and the distance D2 between the centers (central positions) of the two farthest points among the centers (central positions) of five points obtained may be in the following range: Step (1): Heat the electron-emitting member to 1800 K (for example, heat at a temperature increase rate of 500 K / min); Step (2): Continue heating the electron-emitting member to maintain the temperature of the electron-emitting member at 1800 K, while observing the region A occupied by the electron-emitting member on the opening surface (opening end) on the tip side of the electron-emitting member in the opening of the suppressor electrode, and obtain the center (central position) of the region A 20 minutes after the temperature of the electron-emitting member reaches 1800 K; Step (3): Stop heating the electron-emitting member for 20 minutes, and reduce the temperature of the electron-emitting member to less than 1800 K.

[0032] From the viewpoint of easily obtaining sufficient irradiation accuracy even when electrons are emitted after heating and cooling, the distance D2 may be 20 μm or less, 15 μm or less, 10 μm or less, 8 μm or less, 6 μm or less, or 5 μm or less. The distance D2 may be 0 μm or more, more than 0 μm, 1 μm or more, 2 μm or more, 3 μm or more, or 5 μm or more. From these viewpoints, the distance D2 may be 0 μm or more and 20 μm or less, 0 μm or more and 10 μm or less, 0 μm or more and 6 μm or less, more than 0 μm and 20 μm or less, more than 0 μm and 10 μm or less, or more than 0 μm and 6 μm or less. The distance D2, like the distance D1, can be obtained by obtaining the centers of five points using an observation image of the opening surface of the suppressor electrode. The initial heating in step (1) may be performed at 298 K to 1800 K. The distance D2 can be adjusted by the connection mode of the filament and terminal; the amount of deviation in the left and right length of the filament from the center of the electron gun component; the amount of deviation in the joining position of the electron-emitting member from the center of the filament; the joining angle of the electron-emitting member, etc.

[0033] 3 is a diagram showing another example of the opening surface of the suppressor electrode opening on the tip side of the electron-emitting member, showing region A in step (2) when the above-described steps (1) to (3) are repeated five times. In FIG. 3, region A occupied by the electron-emitting member exists on opening surface B of the suppressor electrode. Regions A21 to A25 and centers C21 to C25 represent region A and its center for the first to fifth iterations in step (2) when the steps (1) to (3) are repeated five times. Region A moves in the order of regions A21, A22, A23, A24, and A25 as the steps (1) to (3) are repeated. In this case, of the five centers C21, C22, C23, C24, and C25 obtained by repeating steps (1) to (3) five times, the two centers furthest from each other are C21 and center C25, and the distance between center C21 and center C25 corresponds to distance D2.

[0034] FIG. 4 is a plan view schematically illustrating a connection between a filament and a terminal, showing the connection of the filament to a pair of terminals arranged (arranged) at a distance from each other, viewed from the direction in which the pair of terminals are erected. For convenience, components other than the filament and the terminals are omitted from FIG. 4 . (a) to (c) of FIG. 4 show the connection of an example described below, and (d) of FIG. 4 shows the connection of a comparative example described below. The connection of (a) to (c) of FIG. 4 is effective for achieving the above-described distance D1 range and the above-described distance D2 range because, in a direction perpendicular to the direction in which the pair of terminals are erected, stresses generated at one connection portion and stresses generated at another connection portion located on the opposite side of the one connection portion across a position (e.g., a center position) between the pair of terminals tend to cancel each other out. According to this embodiment, an electron source is provided that includes an electron-emitting member that emits electrons when heated, a filament connected to the electron-emitting member, and a pair of terminals connected to the filament, and satisfies the connection of (a) to (c) of FIG. 4 described below. However, the connection modes of the filament and the terminal in this embodiment are not limited to the connection modes shown in FIGS. 4(a) to 4(c), and various connection modes can be used.

[0035] In (a) of Fig. 4, one filament is connected to a pair of terminals. Specifically, one end of the filament F1 is connected to a connection portion P11 (first connection portion) on a side surface of one terminal T1 (first terminal), and the other end of the filament F1 is connected to a connection portion P12 (second connection portion) on a side surface of the other terminal T2 (second terminal). When viewed from the vertical direction of the pair of terminals (terminals T1 and T2), a line connecting the connection portions P11 and P12 intersects with the arrangement direction (arrangement direction) of the pair of terminals (terminals T1 and T2). In the connection configuration of (a) of Fig. 4, the electron emitting member may be connected to any location on the filament. For example, it may be located between the terminals T1 and T2 when viewed from the vertical direction of the pair of terminals (terminals T1 and T2).

[0036] 4B, two filaments are connected to a pair of terminals. Specifically, one end of a filament (first filament) F21 is connected to a connection portion P21 (first connection portion) on a side surface of one terminal T1 (first terminal), the other end of the filament F21 is connected to a connection portion P22 (second connection portion) on a side surface of the other terminal T2 (second terminal), one end of a filament (second filament) F22 is connected to a connection portion P23 (third connection portion) on a side surface of the terminal T1, and the other end of the filament F22 is connected to a connection portion P24 (fourth connection portion) on a side surface of the terminal T2. When viewed from the direction in which the pair of terminals (terminals T1 and T2) are erected, the connection portions P21 and P23 face each other across the terminal T1, and the connection portions P22 and P24 face each other across the terminal T2. In the connection mode of (b) in Figure 4, the electron-emitting member may be connected to any location on the filament, and for example, when held by filaments F21 and F22, may be located between terminals T1 and T2 when viewed from the vertical direction of the pair of terminals (terminals T1 and T2).

[0037] 4(c), one of the two filaments is connected to one of the pair of terminals, and the other of the two filaments is connected to the other of the pair of terminals. Specifically, one end of a filament (first filament) F31 is connected to a connection portion P31 (first connection portion) on a side surface of one terminal T1 (first terminal), the other end of the filament F31 is connected to a connection portion P32 (second connection portion) on a side surface of the terminal T1, one end of a filament (second filament) F32 is connected to a connection portion P33 (third connection portion) on a side surface of the other terminal T2 (second terminal), and the other end of the filament F32 is connected to a connection portion P34 (fourth connection portion) on a side surface of the terminal T2. When viewed from the direction in which the pair of terminals (terminals T1 and T2) are erected, the connection portions P31 and P32 face each other across the terminal T1, and the connection portions P33 and P34 face each other across the terminal T2. In the connection mode of (c) in Figure 4, the electron emitting member may be connected to any location on the filament, for example, while being held by the filaments F31 and F32, it may be connected to the filaments F31 and F32 when viewed from the vertical direction of the pair of terminals (terminals T1 and T2).

[0038] 4(d), one filament is connected to a pair of terminals. Specifically, one end of the filament F4 is connected to a connection portion P41 on a side surface of one terminal T1 (first terminal), and the other end of the filament F4 is connected to a connection portion P42 on a side surface of the other terminal T2 (second terminal). When viewed from the direction in which the pair of terminals (terminals T1 and T2) are erected, the line connecting the connection portions P41 and P42 does not intersect with the arrangement direction (arrangement direction) of the pair of terminals (terminals T1 and T2).

[0039] The radius R1 of the region A occupied by the electron emitting member in the opening surface of the suppressor electrode may be in the following range: From the viewpoint of preventing the electron emitting member and the suppressor electrode from coming into close proximity to each other and facilitating favorable electron emission, from the viewpoint of easily increasing the brightness of electron emission, and from the viewpoint of easily suppressing change in position of the electron emitting member due to its own weight, the radius R1 may be 200 μm or less, 180 μm or less, 150 μm or less, 125 μm or less, 120 μm or less, 100 μm or less, 90.0 μm or less, 80.0 μm or less, 70.0 μm or less, or 65.0 μm or less. From the viewpoint of easily ensuring the strength of the electron emitting member, easily stabilizing the bond between the electron emitting member and the filament, or easily stabilizing electron emission, the radius R1 may be 1.0 μm or more, 5.0 μm or more, 10.0 μm or more, 20.0 μm or more, 30.0 μm or more, 40.0 μm or more, 50.0 μm or more, or 60.0 μm or more. From these viewpoints, the radius R1 may be 1.0 to 200 μm, 1.0 to 100 μm, 1.0 to 80 μm, 10.0 to 200 μm, 10.0 to 100 μm, 10.0 to 80.0 μm, 30.0 to 200 μm, 30.0 to 100 μm, or 30.0 to 80.0 μm. If the shape of region A is not a perfect circle, the radius R1 is the radius of the smallest circumscribing circle of region A.

[0040] The radius R2 of the opening surface of the suppressor electrode may be in the following ranges. From the viewpoint of easily suppressing emission of excess electrons that may cause noise, the radius R2 may be 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. From the viewpoint of easily suppressing proximity between the electron emitting member and the suppressor electrode and thus favorably emitting electrons, the radius R2 may be 10 μm or more, 30 μm or more, 50 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 150 μm or more, 180 μm or more, or 200 μm or more. From these viewpoints, the radius R2 may be 10 to 1000 μm, 10 to 500 μm, 10 to 300 μm, 50 to 1000 μm, 50 to 500 μm, 50 to 300 μm, 100 to 1000 μm, 100 to 500 μm, or 100 to 300 μm. When the shape of the opening surface of the suppressor electrode is not a perfect circle, the radius R2 is the radius of the largest inscribed circle of the opening surface.

[0041] The ratio X of the radius R1 to the radius R2 (X = [R1 / R2] × 100) may be in the following range. From the viewpoint of preventing the electron emitting member and the suppressor electrode from coming into close proximity and facilitating favorable electron emission, the ratio X may be 80.0% or less, 70.0% or less, 60.0% or less, 50.0% or less, 40.0% or less, or 35.0% or less. From the viewpoint of easily suppressing emission of excess electrons that may cause noise, the ratio X may be more than 0%, 1.0% or more, 5.0% or more, 10.0% or more, 15.0% or more, 20.0% or more, 25.0% or more, or 30.0% or more. From these viewpoints, the ratio X may be greater than 0% and less than 80.0%, greater than 0% and less than 60.0%, greater than 0% and less than 40.0%, 10.0 to 80.0%, 10.0 to 60.0%, 10.0 to 40.0%, 20.0 to 80.0%, 20.0 to 60.0%, or 20.0 to 40.0%.

[0042] The electron gun according to this embodiment includes the electron gun component according to this embodiment and an extraction electrode facing the suppressor electrode. The electron gun according to this embodiment can be used as a Schottky electron gun.

[0043] The extraction electrode can be used to apply an electric field for emitting electrons from the electron-emitting member. The extraction electrode may have an opening (through-hole) through which the electrons emitted from the electron-emitting member pass. The extraction electrode may have a positive potential relative to the suppressor power supply having a negative potential.

[0044] The electron gun according to this embodiment may include a third power supply for applying a voltage to the extraction electrode. The third power supply may be connected to the extraction electrode and may output a positive voltage with respect to the extraction electrode.

[0045] The electron gun according to this embodiment may include an acceleration electrode facing the extraction electrode at a position opposite the suppressor electrode with respect to the extraction electrode. That is, the extraction electrode is disposed between the suppressor electrode and the acceleration electrode. The acceleration electrode can be used to accelerate electrons emitted from the electron-emitting member. The acceleration electrode may have an opening (through-hole) through which the electrons emitted from the electron-emitting member pass. The acceleration electrode may have a positive potential relative to the suppressor power supply having a negative potential.

[0046] The electron gun component according to the present embodiment may include a fourth power supply for applying a voltage to the acceleration electrode. The fourth power supply may be connected to the acceleration electrode and may output a positive voltage with respect to the acceleration electrode.

[0047] The electron beam apparatus according to this embodiment includes the electron gun according to this embodiment. Examples of the electron beam apparatus include an X-ray generator, an electron microscope, a semiconductor manufacturing apparatus, an analytical apparatus (an inspection apparatus such as an electron probe microanalyzer), and a processing apparatus (such as an electron beam evaporation apparatus).

[0048] The present disclosure will be described in more detail below using examples, but the present disclosure is not limited to the following examples.

[0049] <Production of Electron Gun Component> The electron gun component 100 shown in Fig. 1 was obtained by the following procedure: The electron gun component 100 was adjusted so that the electron emission direction was oriented horizontally.

[0050] First, a straight filament was bent to obtain a filament 30. A tungsten filament (cross-sectional shape: circular, diameter: 127 μm) was used in Example 1, a tungsten-rhenium filament (26% by mass of rhenium, cross-sectional shape: circular, diameter: 100 μm) was used in Example 2, and a tungsten-rhenium filament (3% by mass of rhenium, cross-sectional shape: circular, diameter: 100 μm) was used in Examples 3, 4, and Comparative Example 1. Next, a support member S1 with an inter-terminal distance of 5.59 mm and a support member S2 with an inter-terminal distance of 1.5 mm were prepared as support members 40 having an insulating member 42 (material: alumina) and a pair of terminals 44 (Kovar in Example 1 and Comparative Example 1, tungsten in Example 2, and titanium in Examples 3 and 4).

[0051] In Examples 1 and 2, one filament 30 was connected by welding to a pair of terminals 44 in the connection manner shown in FIG. 4( a). In Example 3, two filaments 30 were connected by welding to a pair of terminals 44 in the connection manner shown in FIG. 4( b). In Example 4, one of the two filaments 30 was connected by welding to one of the pair of terminals 44, and the other of the two filaments 30 was connected by welding to the other of the pair of terminals 44 in the connection manner shown in FIG. 4( c). In Comparative Example 1, one filament 30 was connected by welding to a pair of terminals 44 in the connection manner shown in FIG. 4( d). In Examples and Comparative Examples other than Example 2, a support member S1 was used, and in Example 2, a support member S2 was used.

[0052] A cylinder of tungsten single crystal (longitudinal direction of the cylinder: (100) crystal orientation of the tungsten single crystal, radius: 63.5 μm, length: 2000 μm) was prepared as the electron emitting member 10. Next, the side of the base end of the electron emitting member 10 was welded and connected to the side of the bent portion of the filament 30 so that the electron emitting member 10 was positioned between the pair of terminals 44 when viewed from the direction in which the pair of terminals 44 were erected. When two filaments 30 were used, the electron emitting member 10 was held at the bent portions of the two filaments 30.

[0053] The tip 10a of the electron-emitting member 10 was sharpened by electrolytic polishing. Next, a diffusion source (reservoir) 20 of zirconium oxide (ZrO) was formed on the outer periphery of the central part of the electron-emitting member 10 in the electron emission direction.

[0054] A suppressor electrode 50 was prepared, having a cylindrical portion 52, a connecting portion 54, a tapered portion 56, and a tip portion 58. Next, the electron emitting member 10 was inserted into the opening 50a of the suppressor electrode 50, and the support member 40 and the suppressor electrode 50 were connected via the connecting portion 54, thereby obtaining an electron gun component 100. The length of the portion of the electron emitting member 10 that protruded from the opening surface 50b in the electron emission direction was 250 μm. The distance in the electron emission direction between the connection portion of the filament 30 and the pair of terminals 44 and the opening surface 50b of the suppressor electrode 50 was 5.8 mm.

[0055] <Preparation of electron gun> Vacuum chamber (vacuum degree: 1×10 －７ A Schottky electron gun was fabricated by connecting an extraction electrode and various power supplies (the first to third power supplies described above) to the electron gun component 100 in a vacuum chamber (Pa). The distance between the tip 10a of the electron-emitting member 10 and the extraction electrode in the electron emission direction was 0.75 mm, and the opening diameter of the extraction electrode was 0.5 mm. Using the following camera and lens, the focus was adjusted from the tip 10a side of the electron-emitting member 10 to the opening surface 50b of the suppressor electrode 50 in a direction perpendicular to the opening surface 50b. Camera: OM System Solutions Co., Ltd., product name: OM System OM-5 Lens: M.ZUIKO DIGITAL ED 90mm F3.5 Macro IS PRO + ... ZUIKO DIGITAL 2x Teleconverter MC-20 Filter: None Pixels: 3888 x 3888

[0056] <Measurement of Distance D1> The electron emitting member 10 of the above-described electron gun was heated from 298 K to 1800 K at a temperature increase rate of 500 K / min, and then the temperature of the electron emitting member 10 was maintained at 1800 K for 24 hours. Images of the aperture surface 50 b of the suppressor electrode 50 were obtained 1 minute and 24 hours after the temperature of the electron emitting member 10 reached 1800 K. Image analysis software was used to identify the region A occupied by the electron emitting member 10 on the aperture surface 50 b. The center of the smallest circumscribed circle of region A was determined as the center of region A. The distance D1 between the center of region A 1 minute after the temperature of the electron emitting member 10 reached 1800 K and the center of region A 24 hours after the temperature of the electron emitting member 10 reached 1800 K was calculated. The results are shown in Table 1. The radius R1 of the region A occupied by the electron emitting member 10 on the aperture surface 50 b was 63.5 μm, and the radius R2 of the aperture surface 50 b of the suppressor electrode 50 was 200 μm.

[0057] <Measurement of Distance D2> The electron emitter 10 of the above-described electron gun was heated to 1800 K at a temperature increase rate of 500 K / min (step (1): in the initial heating, heating was performed from 298 K to 1800 K). Next, the temperature of the electron emitter 10 was maintained at 1800 K for 20 minutes, and an image of the opening surface 50 b of the suppressor electrode 50 was obtained 20 minutes after the temperature of the electron emitter 10 reached 1800 K (step (2)). Subsequently, heating of the electron emitter 10 was stopped for 20 minutes, and the temperature of the electron emitter 10 was lowered to below 1800 K (step (3)). The procedure of steps (1) to (3) was repeated five times to obtain five images of the opening surface 50 b. For each image, the center (central position) of region A was obtained in the same manner as in measuring distance D1. The distance D2 between the centers (central positions) of the two furthest points among the five centers (central positions) obtained from the five images was calculated. The results are shown in Table 1.

[0058] <Evaluation: Electron Emission Test> A flat fluorescent electrode (fluorescent screen) was placed on the opposite side of the suppressor electrode 50 with respect to the extraction electrode in the electron emission direction of the above-mentioned electron gun. The distance between the tip 10a of the electron emitting member 10 and the fluorescent electrode was 54.7 mm. A current detector (diameter: 0.52 mm) for measuring the probe current was fixed to the center of the surface of the fluorescent electrode opposite to the irradiation surface.

[0059] The electron-emitting member 10 was heated from 298 K to 1800 K at a temperature increase rate of 500 K / min, and then the temperature of the electron-emitting member 10 was maintained at 1800 K for 24 hours or more. While maintaining the temperature of the electron-emitting member 10 at 1800 K, a bias voltage (voltage between the electron-emitting member and the suppressor electrode: −300 V) and an extraction voltage (4700 V) were applied, thereby emitting an electron beam from the electron-emitting member 10. The power supplied to the electron-emitting member 10 when the electron-emitting member 10 was heated from 298 K to 1800 K was 3.0 W in Example 1, 1.5 W in Example 2, 3.3 W in Example 3, 3.4 W in Example 4, and 2.9 W in Comparative Example 1. The optical axis (beam center) of the electron beam was adjusted to coincide with the center of the irradiation surface of the fluorescent electrode. Heating of the electron-emitting member 10 was stopped, and the temperature of the electron-emitting member 10 was lowered to 298K by leaving it to stand for 24 hours or more.

[0060] The electron-emitting member 10 was again heated from 298 K to 1800 K at a temperature increase rate of 500 K / min, and then the temperature of the electron-emitting member 10 was maintained at 1800 K for 20 minutes. While maintaining the temperature of the electron-emitting member 10 at 1800 K, a bias voltage (voltage between the electron-emitting member and the suppressor electrode: −300 V) and an extraction voltage (4700 V) were applied, thereby emitting an electron beam from the electron-emitting member 10. The power supplied to the electron-emitting member 10 when the electron-emitting member 10 was heated from 298 K to 1800 K was the same as the power supplied above. The position at which the maximum probe current was obtained when the current detector was moved together with the fluorescent electrode was determined as the electron beam irradiation position, and the distance between the electron beam irradiation position and the center of the irradiated surface of the fluorescent electrode before the movement was measured. A case where the distance between the electron beam irradiation position and the center of the irradiation surface of the fluorescent electrode before movement was 200 μm or less was judged as "A," and a case where the distance exceeded 200 μm was judged as "B." The results are shown in Table 1.

[0061]

[0062] 10...electron emitting member, 10a...tip, 20...diffusion source, 30, F1, F21, F22, F31, F32, F4...filament, 40...support member, 42...insulating member, 44, T1, T2...terminal, 50...suppressor electrode, 50a...opening, 50b, B...opening surface, 52...cylindrical portion, 54...connecting portion, 56...tapered portion, 58...tip portion, 100...electron gun components, A11, A12, A21, A22, A23, A24, A25...area, C11, C12, C21, C22, C23, C24, C25...center, D1, D2...distance, P11, P12, P21, P22, P23, P24, P31, P32, P33, P34, P41, P42.

Claims

1. An electron gun component comprising an electron-emitting member having a tip that emits electrons when heated, and a suppressor electrode having an opening, wherein the electron-emitting member is inserted into the opening, and after the electron-emitting member is heated from 298K to 1800K, when the temperature of the electron-emitting member is maintained at 1800K and the region occupied by the electron-emitting member on the opening surface on the tip side of the opening is observed, the distance between the center of the region 1 minute after the temperature of the electron-emitting member reaches 1800K and the center of the region 24 hours later is 20μm or less.

2. The electron gun component according to claim 1, wherein the distance between the centers of the two farthest points among the centers of five points obtained by repeating the following steps (1) to (3) five times is 20 μm or less: step (1): heating the electron-emitting member to 1800 K; step (2): continuing to heat the electron-emitting member to maintain the temperature of the electron-emitting member at 1800 K, observing the region occupied by the electron-emitting member on the opening surface on the tip side of the opening, and obtaining the center of the region 20 minutes after the temperature of the electron-emitting member reaches 1800 K; and step (3): stopping heating the electron-emitting member for 20 minutes, and decreasing the temperature of the electron-emitting member to less than 1800 K.

3. An electron gun component according to claim 1, wherein the power supplied to said electron-emitting member when said electron-emitting member is heated from 298K to 1800K is 3.5W or less.

4. An electron gun comprising the electron gun component according to any one of claims 1 to 3 and an extraction electrode facing the suppressor electrode.

5. An electron beam device comprising the electron gun according to claim 4.

Images