JP2011091001A - Method for manufacturing charged particle beam source, charged particle beam source and charged particle beam device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a charged particle beam source which can reliably form a minute projection of an atom level. <P>SOLUTION: The method for manufacturing the charged particle beam source covers a tip of a needle-like fine wire made of first metal with second metal, discharges charged particles from the tip of the needle-like fine wire with the second metal in a melted condition and then solidifies the second metal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a charged particle beam source manufacturing method, a charged particle beam source, and a charged particle beam apparatus.

  A scanning electron microscope (hereinafter abbreviated as SEM) is known as a microscope having a higher resolution than an optical microscope. The image resolution of the current SEM is about 1 nm at a standard acceleration voltage, but there is a strong need for observation with higher resolution. In order to make the charged particles emitted from the charged particle beam source into a beam and observe the sample with high resolution, it is important to increase the beam brightness by reducing the radius of curvature of the tip of the emitter as much as possible. For this reason, an attempt has been made to develop an electron source using minute protrusions in which the electron generation region is sharpened to the atomic level.

  A focused ion beam (hereinafter referred to as FIB) apparatus is also known as an ion microscope having a higher resolution than an optical microscope. The main application in the current FIB apparatus is processing of a fine region (sputter processing of a sample by FIB irradiation) using the fact that ions are heavier than electrons. In the development of the FIB apparatus, efforts are made to increase the processing speed by increasing the beam current density. However, recently, an ion microscope function that enables observation and analysis with higher resolution than SEM without damaging the sample by ion beam irradiation has been strongly desired. In order to achieve this, attention has been focused on an ion source that uses the tip of a fine projection in which the ion generation region at the tip of the emitter is sharpened to the atomic level.

  In the following Patent Document 1, an electrolytic polishing method is disclosed as a method for sharpening the emitter tip.

  In the following Patent Document 2, an attempt is made to obtain fine protrusions having a number of atoms of several or less by coating and heating a needle-like thin wire such as tungsten sharpened beforehand by electrolytic polishing with another metal. . This utilizes the property that the metal atoms covering the tip surface of the needle-like thin wire diffuse and accumulate. Patent Document 2 below describes a method of forming a single atom-sized terminal electron source by vacuum-depositing and heat-treating a second metal on a needle-like thin wire made of a first metal.

  Non-Patent Document 1 described below describes a method of obtaining an ion source having a single-atom-sized terminal shape by electroplating and heat treatment as a method for coating the emitter tip with a noble metal.

Japanese Patent Publication No.57-31247 JP 2006-134638 A

Proceedings of Japan Journal of Applied Physics, 2006, Vol. 45, pages 8972-8983 “Noble Metal / W (111) Single Atom Tips and Der Field Electron and AEON Characterization ”

  In the electrolytic polishing method described in Patent Document 1, it is difficult to make the tip radius 50 nm or less, and it is therefore difficult to obtain atomic level microprotrusions that satisfy the above requirements.

  The vacuum vapor deposition method described in Patent Document 2 requires time for preparation and vapor deposition for making the apparatus an ultra-high vacuum because work is performed in an ultra-high vacuum. Further, if the film thickness is thinner than the appropriate thickness, there is a problem that the coated metal atoms are less likely to diffuse at the tip of the needle-like thin wire, and the coated metal minute projections are less likely to be formed at the tip.

  In addition to the above method, it is also conceivable to coat the needle-like fine wire with metal by electroplating. When electroplating is used, a sufficiently thick metal film can be easily coated. On the other hand, since electroplating uses an electrochemical reaction using a solution, the surface of the needle-like fine wire exposed to the atmosphere is oxidized, or impurities from the solution are present at the interface between the plating film and the needle-like fine wire. There is a concern of intrusion. Therefore, the reliability of the process of surface diffusion of the atoms of the coated metal at the tip of the needle-like thin wire is not sufficient.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method of manufacturing a charged particle beam source capable of forming atomic level microprotrusions with high reliability.

  The inventor of the present application diligently studied a method of manufacturing a charged particle beam source having an emitter having minute projections having an atom-level terminal shape, and the following knowledge has been obtained.

  In order to achieve the above object, in the method of manufacturing a charged particle beam source according to the present invention, the tip of a fine needle wire made of the first metal is covered with the second metal, and the needle shape is obtained while the second metal is melted. Charged particles are emitted from the tip of the thin wire to solidify the second metal.

  According to the method of manufacturing a charged particle beam source according to the present invention, the amount of the second metal that covers the needle-like thin wire can be appropriately adjusted by the atomic level size. Thereby, the second metal at the tip of the emitter can be sharpened at the atomic level.

1 is a diagram showing a schematic configuration of a charged particle beam source 1 according to Embodiment 1. FIG. It is a schematic block diagram of the charged particle beam source tip 8. 5 is a diagram for explaining details of a process for manufacturing the charged particle beam source 1 according to Embodiment 1. FIG. It is the figure which expanded the front-end | tip part 25 of the acicular thin wire | line 4 in FIG. It is a figure which compares the acicular thin wire | line 4 in Embodiment 1 with the acicular thin wire | line 4 in this Embodiment 2. FIG. It is a figure which shows another example of the shape of the acicular thin wire | line 4 in Embodiment 2. FIG. 10 is a flow showing a method of manufacturing the charged particle beam source 1 according to the third embodiment. 10 is a flow showing a method for manufacturing the charged particle beam source 1 according to the fourth embodiment. 10 is a flow showing a method for manufacturing the charged particle beam source 1 according to the fourth embodiment. 10 is a flow showing a method of manufacturing the charged particle beam source 1 according to the fifth embodiment. It is a block diagram of the charged particle beam source manufacturing apparatus 30 which performs the manufacturing method of the charged particle beam source 1 demonstrated in Embodiment 1-6. FIG. 10 is a schematic diagram showing a configuration of a charged particle beam apparatus 100 according to an eighth embodiment.

  In the following description, a charged particle is a charged particle and refers to a positive ion, a negative ion, and an electron. The needle-like thin line refers to a member before the coating metal is attached, and the emitter is a needle-like thin line coated with a coating metal at least at the tip.

<Embodiment 1>
FIG. 1 is a diagram showing a schematic configuration of a charged particle beam source 1 according to Embodiment 1 of the present invention. The charged particle beam source 1 operates in a vacuum vessel 7. The charged particle beam source 1 has at least an emitter 2 and an extraction electrode 3. The emitter 2 has a needle-like thin wire 4 made of a first metal and a covering metal 5 that covers at least the tip of the needle-like thin wire 4. The covering metal 5 is made of a second metal different from the first metal.

  The first metal is a refractory metal having a melting point of 2500 ° C. or higher. For example, any of tungsten (W), molybdenum (Mo), rhenium (Re), niobium (Nb), and tantalum (Ta) can be used. The needle-like thin wire 4 has a diameter of about 0.1 mm to 0.2 mm, is made of the above-mentioned single crystal material of a refractory metal, and has a specific crystal plane at the tip.

  The coated metal 5 made of the second metal is a metal having a melting point lower than that of the first metal and not lower than 900 ° C. and lower than 2500 ° C. For example, any of gold (Au), silver (Ag), platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), rhodium (Rh), copper (Cu), nickel (Ni) Can be used.

  Since the method for coating the needle-shaped thin wire 4 with the coating metal 5 is an important point of the present invention, it will be described in detail again.

  The emitter 2 is connected to a high voltage power source for accelerating the emitted charged particles, a current power source for heating the emitter, and an ammeter for measuring the emitted charged particle beam current (not shown). The extraction electrode 3 is connected to a high voltage power source for discharging charged particles, an ammeter, and the like (not shown). A positive voltage is applied to the emitter 2 when the charged particles to be emitted are positive ions, and a negative voltage is applied to the emitter 2 when the charged particles to be emitted are electrons or negative ions.

  When a potential difference is formed between the emitter 2 and the extraction electrode 3, a high electric field is generated at the tip of the emitter 2, and the charged particles 6 are emitted from the tip of the coated metal 5. The charged particles 6 are particles such as electrons and gas ions near the tip of the emitter 2, for example. When the charged particles 6 are ions, a gas to be ionized is supplied in the vicinity of the tip of the emitter 2, and this gas is ionized by a high electric field formed at the tip of the emitter 2. In this case, a gas source and a gas supply unit are required. In addition to the above, the charged particle beam source 1 may include a cooling device that cools the emitter to a low temperature in order to increase the ion current and increase the beam brightness.

  FIG. 2 is a schematic configuration diagram of the charged particle beam source tip 8. The emitter 2 is a component of the charged particle beam source tip 8. The charged particle beam source tip 8 includes an emitter 2, a filament 9, an electric terminal 10, and an insulator 11.

  The emitter 2 is formed by covering a needle-like thin wire 4 made of a first metal with a covering metal 5 made of a second metal at least at the tip. The filament 9 holds the emitter 2 and serves as a heating source for heating the emitter 2. The electrical terminal 10 holds the filament 9. The insulator 11 supports the electric terminal 10.

  The needle-like thin wire 4 is spot welded to the filament 9, and the filament 9 is spot welded to the electric terminal 10. The electric terminal 10 is metalized and fixed to the insulator 11. When a current is passed between the two electrical terminals 10, the filament 9 is heated by resistance, and the emitter 2 is also heated by heat conduction.

  The configuration of the charged particle beam source 1 according to the first embodiment has been described above. Below, the method to manufacture the charged particle beam source 1 is demonstrated.

  The point of the present invention is that a charged particle beam capable of covering the tip of the needle-like wire 4 with a coating metal 5 with a thickness of several atoms and supplying the coating metal 5 to the tip of the emitter 2 as required. The structure of source 1 and the method of manufacturing it. The outline of the manufacturing method of the charged particle beam source 1 is as follows (step 1) to (step 4). Details of the manufacturing method will be described again with reference to FIGS.

(Step 1) The needle-like thin wire 4 is brought into contact with the molten coating metal 5 or immersed in the molten coating metal 5.

(Step 2) Then, the electric field is concentrated on the tip of the emitter 2 while the coated metal 5 is kept in a molten state on the needle-like thin wire 4, and electrons or ions are emitted.

(Step 3) In the state where the emitter 2 is emitting electrons or ions, the heating for melting the coated metal 5 is stopped. Through the above steps, the tip of the emitter 2 is sharpened at the atomic level.

(Step 4) If sharpening is insufficient, heat treatment is further performed at a temperature equal to or lower than the melting point of the coated metal 5. Due to the surface migration effect described later, the tip of the emitter 2 is sharpened to a monoatomic level.

  FIG. 3 is a diagram for explaining details of a process for manufacturing the charged particle beam source 1 according to the first embodiment. Here, the situation where the covering metal 5 is attached to the tip of the needle-like thin wire 4 is shown. All these steps are performed in an ultra-high vacuum vessel. Hereinafter, each diagram of FIG. 3 will be described.

  FIG. 3A shows a state in which the tungsten needle-like wire 4 sharpened by electrolytic polishing is heated and washed at a high temperature in order to remove impurities such as oxide adhering to the surface. Impurities 23 adhering to the surface of the needle-like thin wire 4 are desorbed while maintaining the tip shape of the needle-like thin wire 4 by high-temperature instantaneous heating at 2000 ° C. for about 0.5 seconds. At this time, in order to prevent the desorbed impurities 23 from adhering to the second metal 21, a conductive shutter 22 is provided between the needle-like thin wire 4 and the surface of the second metal 21.

  FIG. 3B shows a state in which the tip of the needle-like thin wire 4 whose surface has been cleaned is brought into contact with the surface of the molten second metal 21. The shutter 22 is moved immediately before the tip of the needle-like thin wire 4 is brought into contact with the surface of the molten second metal 21 to keep it away from the needle-like thin wire 4. As soon as the tip of the needle-like thin wire 4 comes into contact with the surface of the second metal 21 in the molten state, the molten second metal diffuses thinly into the conical tip of the needle-like thin wire 4 and becomes in a coated state. .

  At the time of FIG. 3B, the needle-like thin wire 4 is heated to near the melting point of the second metal 21. If the needle-like thin wire 4 is at a temperature much lower than the melting point of the second metal 21 (for example, room temperature), the tip portion 25 of the needle-like thin wire 4 will not reach the tip at the moment when it contacts the molten second metal 21 surface. Since it solidifies into a fixed shape, it is not preferable from the viewpoint of terminating the tip 25 at the monoatomic level. Therefore, it is preferable to heat the needle-like thin wire 4 to the above temperature.

  In addition, in order to coat the second metal 21 on the needle-like thin wire 4, it is not necessary to immerse the needle-like thin wire 4 deeply into the molten second metal 21. It is not preferable to immerse the needle-like thin wire 4 deeply into the molten second metal 21 because the second metal 21 is excessively attached to the surface of the needle-like fine wire 4 and it becomes difficult to form atomic level microprotrusions at the tip. Therefore, it is good to immerse or contact the second metal 21 to such an extent that the second metal 21 is appropriately attached to the needle-like thin wire 4.

  FIG. 3C shows a state in which the needle-like thin wire 4 whose tip is in contact with the surface of the molten second metal 21 is separated from the second metal 21. Although the second metal 21 is thinly coated on the needle-like thin wire 4, the tip portion does not reflect the shape of the needle-like thin wire 4, and the tip radius is slightly increased. This is because when the needle-like thin wire 4 is separated from the melted second metal 21, the liquid column connecting the tip of the needle-like thin wire 4 and the surface of the melted second metal 21 is separated, This is because it accumulates. This situation is the same as the state in which the second metal 21 is excessively attached to the tip, and it is difficult to form atomic level microprotrusions at the tip.

  FIG. 3 (d) removes the excessive second metal 21 coated on the tip from the situation of FIG. 3 (c), and makes the film thickness thin enough to reflect the tip shape of the original needle-like thin wire 4. A process is shown. Excess second metal 21 can be removed by releasing second metal 21 as ions and depleting the coating metal near the tip. The procedure for releasing the second metal 21 as the ions 27 is as follows.

(FIG. 3D: Procedure 1) A shutter 22 is inserted between the needle-like thin wire 4 (emitter) spaced from the surface of the second metal 21 and the second metal 21.

(FIG. 3D: Procedure 2) The shutter 22 is set to the ground potential, and a positive high voltage is applied to the needle-like thin wire 4. As a result, the shutter 22 becomes a positive ion extraction electrode.

(FIG. 3D: Procedure 3) A hole 26 is provided in the shutter 22 (extraction electrode). When ions are emitted from the tip of the needle-like thin wire 4, the position of the shutter 22 is adjusted so that the tip portion 25 of the needle-like thin wire 4 is located at the center of the hole 26.

(FIG. 3D: Procedure 4) For example, a large current of 100 μA or more is passed through the needle-like thin wire 4 to release ions of the second metal 21 from the tip of the needle-like thin wire 4. Thereby, the 2nd metal 21 around the front-end | tip part 25 of the acicular thin wire | line 4 reduces, and the front-end | tip part 25 will be in a thin film state.

  4 is an enlarged view of the distal end portion 25 of the needle-like thin wire 4 in FIG. Hereinafter, each diagram of FIG. 4 will be described.

  FIG. 4A is an enlarged view of the tip of the needle-like thin wire 4 before the second metal 21 is attached. Crystal surfaces 28a, 28b, 28c, and 28d are formed on the tip surface of the needle-like thin wire 4 by high-temperature instantaneous heating for cleaning the surface of the needle-like thin wire 4. The crystal plane located at the tip of the needle-like thin wire 4 is, for example, a plane in which about 5 to 20 atoms are aligned two-dimensionally in one direction.

  FIG. 4B shows a state where the surface of the needle-like thin wire 4 is covered with the second metal 21 film in the state of FIG. When the tip of the acicular thin wire 4 is brought into contact with or immersed in the surface of the molten second metal 21, the coating film 21a of the second metal 21 reflects the surface shape of the acicular thin wire 4 as shown in FIG. Adhering excessively thickly.

  FIG.4 (c) is an enlarged view of the front-end | tip part 25 in the state of FIG.4 (b). The amount of the coating film of the second metal 21 is particularly large in the emitter tip portion 25. Even if the second metal 21 is solidified in this state, it is difficult to form atomic level microprotrusions.

  FIG. 4D is a diagram showing a state in which the thickness of the coating film of the second metal 21 is processed so as to reflect the surface shape of the needle-like thin wire 4. The coating film on the crystal surface at the tip of the needle-like thin wire 4 is processed to a thickness of several atomic layers or less. The present inventors have found that when the second metal 21 is solidified in this state, minute projections at the atomic level are easily formed at the tips of the needle-like thin wires 4.

  FIG.4 (e) is an enlarged view of the front-end | tip part in the state of FIG.4 (d). The thickness of the second metal 21 film attached to the needle-like thin wire 4 is about 1 to 10 atoms. In this state, the following steps are executed.

(FIG. 4 (e): Step 1) The emitted ion current is adjusted to a minute current of about 1 μA or less, and it is confirmed that ion emission is performed stably.

(FIG. 4 (e): Step 2) If stable ion release can be confirmed for about 30 minutes, the heating current for heating the needle-like thin wire 4 is stopped. By stopping the heating current, the temperature of the second metal 21 on the needle-like thin wire 4 is lower than the melting point, and the second metal 21 is solidified. At the same time as solidification, ion emission stops.

(FIG. 4E): Step 3) The acceleration voltage is lowered to the ground potential. As a result of the above operation, the fine protrusion 25a composed of the atoms of the second metal 21 is formed on the crystal surface at the tip of the needle-like thin wire 4.

  FIG. 4F is an enlarged view of the minute protrusion 25a. The microprotrusion 25a has a cone shape in which the length of one side of the bottom surface is about 3 to 5 atoms.

  As described above, in the first embodiment, the needle-shaped thin wire 4 is covered with the second metal 21 and a voltage is applied to release the particles of the second metal 21. Thereby, the film thickness of the second metal 21 can be adjusted to about 1 to 10 atoms. When the second metal 21 is solidified in this state, the thin film of the second metal 21 protrudes and the tip is sharpened. At this time, if the film thickness of the second metal 21 is in the above state, the sharpened tip portion 25 is likely to have a minute size at the atomic level. Therefore, the emitter 2 sharpened to the atomic level can be obtained with high reliability.

  Further, in the first embodiment, the tip 25 of the needle-like thin wire 4 is brought into contact with or immersed in the second metal 21 to cover the second metal 21. According to this method, unlike the method of attaching the second metal 21 by chemical vapor deposition as in Patent Document 2, it is possible to coat the second metal 21 with a sufficient amount without unevenness. The reliability of the process is improved.

<Embodiment 2>
In Embodiment 2 of the present invention, a configuration will be described in which the shape of the needle-like thin wire 4 is deformed to facilitate the appropriate adjustment of the thickness of the second metal 21 coating. Since other configurations and processes are the same as those of the first embodiment, the following description will focus on differences.

  In the first embodiment, it has been described that the coating of the second metal 21 is formed on the distal end portion 25 of the needle-like thin wire 4 by contacting or immersing the needle-like fine wire 4 in the second metal 21. However, if the melted second metal 21 adheres excessively to the tip of the needle-like thin wire 4, the radius of curvature of the tip 25 becomes excessively large. If the coating metal (second metal 21) is excessively accumulated at the tip, the shape of the crystal surface at the tip of the needle-like thin wire 4 is not reflected in the shape of the tip 25, and it becomes difficult to form the minute protrusion 25a. Therefore, in the second embodiment, the shape of the needle-like thin wire 4 is devised to prevent an increase in the radius of curvature due to an excessive coating metal.

  FIG. 5 is a diagram comparing the needle-like thin wire 4 in the first embodiment and the needle-like thin wire 4 in the second embodiment. Hereinafter, each diagram of FIG. 5 will be described.

  FIG. 5A shows the shape of the needle-like thin wire 4 in the first embodiment. In Embodiment 1, the acicular thin wire 4 is obtained by sharpening a cylindrical thin wire by electrolytic polishing, for example.

  FIG. 5B shows the shape of the needle-like thin wire 4 in the second embodiment. In the second embodiment, the concave portion 63 is provided on the side surface at a position slightly away from the distal end portion 25 of the needle-like thin wire 4 toward the center portion. The recess 63 may be provided over the entire circumference of the side surface of the needle-like thin wire 4 or may be provided only on a part of the side surface.

  FIG. 5C shows a state where the needle-like thin wire 4 of FIG. 5A is covered with the second metal 21. When the amount of the second metal 21 is large, the radius of curvature of the second metal 21 of the tip end portion 25 becomes larger than the tip curvature of the needle-like thin wire 4, and it becomes difficult to form the minute protrusion 25a.

  FIG. 5 (d) shows a state where the needle-like thin wires 4 of FIG. 5 (b) are covered with the second metal 21. Excess second metal 21 that causes an increase in the radius of curvature of the tip is pulled in by the tension in the recess 63, and the coating metal of the tip 25 is likely to be thinner than in FIG. As a result, the coating on the tip 25 becomes a thin film having a thickness of about one to several atoms, and the microprojections 25a are easily formed.

Examples of the method for forming the recess 63 include the following.
(Example 1) The recessed part 63 can be formed by the sputter | spatter process by focused ion beam irradiation.

(Example 2) Before the tip of the needle-like thin wire 4 is processed into a needle shape by electrolytic polishing, the tip and the opposite side are masked with wax or the like and electropolished. Thereby, only the part which is not masked with wax etc. can be grind | polished finely than another part, and the site | part corresponding to the recessed part 63 can be processed into a cross-sectional concave shape.

(Example 3) An electrolyte film is stretched on a ring-shaped electrode (not shown), the needle-shaped thin wire 4 is penetrated without breaking the electrolyte film, and the recess 63 is processed between the ring-shaped electrode and the emitter. Apply current. As a result, a concave portion 63 (circumferential groove) having a thickness of the electrolytic solution film is formed, so that the circumferential groove as shown in FIG. 5B can be processed by moving the position of the electrolytic solution film and controlling the current. .

  FIG. 6 is a diagram illustrating another shape example of the needle-like thin wire 4 in the second embodiment. 6A shows an example of a shape in which a convex portion 66 is provided on the side surface of the needle-like thin wire 4, and FIG. 6B shows an example of a shape in which a plurality of concave portions 67 are provided.

  The convex portions 66 in FIG. 6A can be formed by growing a tungsten deposition film on the circumference of the side surface of the needle-like thin wire 4 by FIB assist deposition. The growth of the tungsten deposition film is performed while rotating the needle-like thin wires 4. The height of the convex portion 66 is approximately 1 to 10 μm, and the width is approximately 10 to 100 μm.

  After electrolytic polishing of the needle-like fine wire 4 made of tungsten, the above-described convex portion 66 is formed, and then the filament is energized and heated in an ultra-high vacuum to make the needle-like fine wire 4 about 2000 ° C., 0.1-1 Impurities attached to the surface of the needle-like thin wire 4 are removed by instantaneous heating for 2 seconds. By this work, the coated metal in the molten state is easily wetted by the needle-like thin wires 4. In particular, the second metal 21 is stored between the portion covering the convex portion 66 and the adjacent convex portions 66.

  Due to the above-described action of the convex portion 66, the excess second metal 21 is accumulated around the convex portion 66, and the coating of the second metal 21 becomes a thin film with a thickness of 1 to several atoms at the tip portion 25, and the minute projection 25a is easily formed.

  In the example of FIG. 6A, the convex portions 66 are provided in a circumferential shape, but the same effect can be obtained by arranging the convex portions 66 in the form of dots on the side surfaces of the needle-like thin wires 4.

  FIG. 6B shows an example of a shape in which a plurality of concave portions similar to those in FIG. Here, an example in which a thread groove-like recess 67 is formed is shown. The recess 67 can be formed by repeating the electropolishing using the ring electrode described in FIG. 5D while moving the processing position. The structure applied to the needle-like thin wire 4 is not limited to processing the groove-shaped recess 67 in a circumferential shape, and may be processed in a dimple shape, for example.

  As described above, according to the second embodiment, since the excess second metal 21 is stored in the concave portions 63 and 67 and the convex portion 66, the coating of the second metal 21 on the tip portion 25 is sufficiently thin, Atomic level microprotrusions 25a are easily formed. Further, when the minute protrusion 25 a is regenerated, the second metal 21 stored in the concave portion 67 or the convex portion 66 can be heated and melted and supplied to the tip portion 25. As a result, the minute protrusions 25a are easily regenerated by the depletion of the second metal 21, and the life of the charged particle beam source 1 can be extended.

  In the example shown in FIG. 5 to FIG. 6, an example in which irregularities are provided in addition to the distal end portion 25 of the needle-like thin wire 4 is shown. A shape (not shown) in which a thin wire having a thin diameter is wound or a shape (not shown) in which vertical stripes parallel to the axis of the needle-like wire 4 are provided by a focused ion beam may be used. Even with such a needle-like thin wire 4, the second metal 21 layer covered at the tip is in an extremely thin state, and the minute protrusion 25a is easily formed.

<Embodiment 3>
In the third embodiment of the present invention, the entire flow of the manufacturing process of the charged particle beam source 1 will be described from the viewpoint of sharpening the emitter 2 described in the first and second embodiments. Since details of each process are the same as those described in the first and second embodiments, details such as drawings are omitted as appropriate.

  FIG. 7 is a flowchart showing a method for manufacturing the charged particle beam source 1 according to the third embodiment. Hereinafter, each step of FIG. 7 will be described.

(FIG. 7: Step S701: Second metal coating step)
In this step, a coating metal made of the second metal 21 is attached to the tip of the needle-like thin wire 4. First, the coated metal is held in a molten state, and the needle-like thin wires 4 are brought into contact with or immersed in the molten coated metal surface. Thereby, a covering metal adheres to the acicular thin wire 4.

(FIG. 7: Step S701: Second metal coating step: Supplement 1)
When the needle-like thin wires 4 are immersed deeply or for a long time in the molten coated metal, the coated metal is excessively attached with a thickness greater than desired, and the micro protrusions 25a are hardly formed as described in the previous embodiment. Become. Therefore, it is important to immerse a small portion of the tip of the needle-like thin wire 4 only for a short time. As a result, the molten coated metal quickly diffuses thinly on the surface of the needle-like thin wire 4 due to surface tension to coat the tip portion 25. In order to realize short-time contact or shallow immersion, a linear drive mechanism of the charged particle beam source 1 may be used.

(FIG. 7: Step S701: Second metal coating step: Supplement 2)
In this step, the coating film thickness may be increased by simply contacting or immersing the needle-like thin wire 4 in the melted second metal 21. Therefore, you may employ | adopt the shape of the acicular thin wire | line 4 as demonstrated in Embodiment 2. FIG.

(FIG. 7: Step S701: Second metal coating step: Supplement 3)
In this step, if the temperature of the molten coated metal is much higher than the melting point, evaporation will increase and vapor deposition will occur on the inner walls of the charged particle beam source tip 8 and the vacuum vessel 7. This state is not preferable because it causes problems such as insulation failure. Therefore, it is desirable to set the temperature of the molten coated metal to about 50 ° C. higher than the melting point.

(FIG. 7: Step S701: Second metal coating step: Supplement 4)
In this step, when the needle-like thin wire 4 is immersed in the molten coating metal, if the temperature of the needle-like thin wire 4 is low (for example, room temperature), the temperature of the molten coating metal may be lowered, and may be lowered below the melting point. is there. For this reason, the temperature of the acicular thin wire | line 4 is maintained in the state heated to the same extent as the temperature of the melt | dissolved coating metal.

(FIG. 7: Step S702: Charged Particle Release Step: Step 1)
In this step, the coated metal adhering to the tip of the needle-like thin wire 4 is sharpened. First, the needle-like thin wire 4 thinly coated with the second metal 21 is separated from the heating container. Next, the extraction electrode 22 is inserted between the needle-like thin wire 4 and the heating container, and the charged particle beam source 1 and the extraction electrode 22 are arranged so that the tip of the emitter 2 is arranged at the center of the hole 26 provided in the extraction electrode 22. Adjust the position of.

(FIG. 7: Step S702: Charged Particle Release Step: Step 2)
The charged particle beam source 1 is energized with the needle-like thin wires 4 arranged at the optimum position, and the coated metal adhering to the emitter 2 is melted again. The melting temperature at this time is set to be approximately the same as the melting point of the second metal 21.

(FIG. 7: Step S702: Charged Particle Release Step: Step 3)
After confirming that the second metal 21 on the emitter 2 is in a molten state, a positive high voltage is gradually applied to the charged particle beam source 1 to discharge charged particles (ions of the second metal 21). Here, since the extraction electrode 22 is set to the ground potential, the high voltage is applied only to the charged particle beam source 1 to adjust the electrolysis, but the charged particle beam source 1 is maintained at a constant voltage and the voltage is applied to the extraction electrode 22. May be.

(FIG. 7: Step S702: Charged Particle Release Step: Step 4)
When the second metal 21 at the tip of the emitter 2 is excessive and the radius of curvature of the tip of the emitter 2 is large, the emission ion current is set to a large current of 100 μA or more, the emission amount is increased, and the amount of the second metal 21 at the tip 25 is positively increased. Make it less. On the other hand, when the amount of the second metal 21 at the tip of the emitter 2 is appropriate and substantially the same as the tip radius of curvature of the needle-like thin wire 4, the emitted ion current is set to a small current of about 1 μA. Even when the second metal 21 at the tip of the emitter 2 is excessive, if the second metal amount 21 at the tip of the emitter 2 becomes an appropriate amount after the emission of an appropriate large current, the emitted ion current is adjusted to a small current. .

(FIG. 7: Step S703: Second metal solidification step)
In a state where the emission ion current is adjusted to a small current in step S702, the state where ions are generated from the needle-like thin wire 4 is continued for about several minutes to one hour, and then the energization for heating the needle-like thin wire 4 is stopped. To do. When the heating temperature is equal to or lower than the melting point of the second metal 21, the coating of the second metal 21 is solidified, and at the same time, ion emission is stopped. After confirming that ion emission has stopped, the voltage applied to the needle-like thin wire 4 is lowered to the ground potential. By this step, the coated metal made of the second metal 21 is sharpened from the tip radius of the needle-like thin wire 4, and sharpened from the tip radius of the molten second metal 21 immediately after immersion, and the tip radius is 50 nm. It becomes the following.

(FIG. 7: Step S704: Single atom termination step)
In this step, the second metal 21 at the tip of the emitter 2 formed in step S703 is further sharpened to a single atom level size. In step S703, the tip of the emitter 2 is sharpened to a tip radius of 50 nm or less, but may not be terminated at a single atom level. Therefore, in this step, the tip 25 of the emitter 2 is further sharpened and terminated at the single atom level.

(FIG. 7: Step S704: Single Atom Termination Step: Specific Procedure)
After step S703, the needle-like thin wire 4 is heated again. The heating temperature is set to be equal to or lower than the melting point of the second metal 21. By such heating, the property that several layers of the second metal 21 are stacked at the tip of the needle-like thin wire 4 acts (surface migration effect: see Patent Document 2), and the tip is sharpened to a size of about one atom. A protrusion 25 is formed. For example, when the second metal 21 is platinum (Pt), the tip 25 of the emitter 2 can be terminated at a single atom level by heating at 700 ° C. for 30 minutes.

  As described above, according to the third embodiment, a voltage is applied to the needle-like thin wire 4 that is thinly coated with the second metal 21 to release ions of the second metal 21, and the minute protrusion 25 a is formed on the distal end portion 25. Can be formed.

  Further, according to the third embodiment, the microprotrusion 25a can be further sharpened by using the surface migration effect of the second metal 21, and can be terminated at a single atom level.

  In Embodiment 3, as the second metal 21, gold (Au), silver (Ag), platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), rhodium (Rh), Either copper (Cu) or nickel (Ni) is used. These metals are suitable for use in the method for manufacturing a charged particle beam source according to the present invention because the above-described surface migration effect is likely to occur.

  In the third embodiment, the second metal 21 has been described on the assumption that it is a metal composed of a single element of the above metal. However, if the same effect can be obtained, any one of the above elements can be used. The alloy may be used. The same applies to the following embodiments.

<Embodiment 4>
In Embodiment 4 of the present invention, an example will be described in which, in addition to the method for manufacturing charged particle beam source 1 described in Embodiment 3, a process for newly checking the state of tip portion 25 is provided.

  FIG. 8 is a flow showing a method for manufacturing the charged particle beam source 1 according to the fourth embodiment. Hereinafter, each step of FIG. 8 will be described.

(FIG. 8: Steps S801 to S804)
These processes are the same as steps S701 to S704 in FIG.

(FIG. 8: Step S805: Release of charged particles)
In this step, ions or electrons are emitted using the emitter 2 that has completed the single atom termination step. In the case of releasing ions, a gas (for example, neon gas) is introduced into the vacuum vessel 7 and an acceleration voltage is applied to the emitter 2, whereby gas ions are released from the tip of the emitter 2.

(FIG. 8: Step S806: Tip Evaluation)
In this step, whether or not the tip of the emitter 2 is sharpened is determined based on the state of the charged particles emitted in step S805. If the evaluation is good, this flow is terminated. If the evaluation is not good, the process returns to step S804 and the same process is repeated.

(FIG. 8: Step S806: Tip Evaluation: Specific Procedure)
A fluorescent screen is installed in the direction of emission of ions or electrons. When charged particles are emitted from the emitter 2 toward the fluorescent plate, a bright spot corresponding to the atomic arrangement at the tip of the emitter 2 is observed. If the processing in step S804 is appropriate and single atom termination is performed, only one bright spot is observed. If one bright spot is observed stably, it is determined that the evaluation of the tip 25 is good. If the bright spot blinks in an unstable manner, or if the bright spot is not deviated into one in a plurality of states for a long time, it is determined that the evaluation of the tip portion 25 is bad.

  As described above, according to the fourth embodiment, since a process for evaluating the degree of sharpening of the tip 25 is newly provided, the tip of the emitter 2 can be sharpened with high reliability.

<Embodiment 5>
In the fifth embodiment of the present invention, an example in which the reworking procedure is changed according to the evaluation result in the tip evaluation step (step S806 in FIG. 8) described in the fourth embodiment will be described.

  FIG. 9 is a flowchart showing a method for manufacturing the charged particle beam source 1 according to the fourth embodiment. Hereinafter, each step of FIG. 9 will be described.

(FIG. 9: Steps S901 to S905)
These processes are the same as steps S801 to S805 in FIG.

(FIG. 9: Step S906: Tip Evaluation)
In this step, whether or not the tip of the emitter 2 is sharpened is determined based on the state of the charged particles emitted in step S905. If the evaluation is good, this flow is ended. If the evaluation is not good, the process proceeds to step S907. The specific procedure for evaluating the tip may be the same as step S806 in FIG.

(FIG. 9: Step S907: tip shape only NG)
If the microprotrusions 25a are formed but not sharpened to the atomic level, the process returns to step S904 and the single atom termination step is performed again. For example, if charged particles are emitted toward the fluorescent plate and only one bright spot is observed stably, it can be seen that the microprojections 25a are monoatomic.

(FIG. 9: Step S907: Overall shape is NG)
When the shape of the tip 25 is not sharpened as a whole, such as when the radius of curvature of the tip 25 is large or the minute protrusion 25a is not formed, the process returns to the previous step S902. For example, when charged particles are emitted toward the fluorescent plate and a plurality of bright spots are observed in an unstable manner, it can be seen that the shape of the tip 25 is not sharpened as a whole.

  As described above, in the fifth embodiment, the example in which the reworking procedure is changed according to the evaluation result of the tip evaluation process has been described.

<Embodiment 6>
In the sixth embodiment of the present invention, the method for manufacturing the charged particle beam source 1 described in the fifth embodiment will be described in more detail. In particular, details of the step before coating the second metal 21 and the step of sharpening the tip 25 will be described.

  FIG. 10 is a flow showing a method for manufacturing the charged particle beam source 1 according to the fifth embodiment. Hereinafter, each step of FIG. 10 will be described.

(FIG. 10: Step S1001: Electropolishing process)
In this step, the tip of the fine needle wire 4 is electropolished to sharpen the radius of curvature of the tip 25 to about 50 nm. Any known technique can be used for specific methods such as the polishing liquid, polishing time, and current. After the tip of the needle-like thin wire 4 is polished, the polishing portion is sufficiently washed with water and dried, and then placed in the vacuum vessel 7.

(FIG. 10: Step S1002: High-temperature heat cleaning process)
In this step, the impurities 23 adhering to the surface of the needle-like thin wire 4 subjected to electropolishing are removed by instantaneous heating at a high temperature (about 2000 ° C. for 0.1 to 1 second). In this step, the atoms on the tip surface of the needle-like thin wire 4 are rearranged, and many crystal planes are formed. This step is very important because the minute protrusions 25a of the second metal 21 are easy to be formed on the surface where no impurities are attached and the crystal plane is formed.

(FIG. 10: Step S1003: Second metal coating step)
This step is the same as steps S701, S801, and S901.

(FIG. 10: Step S1004: First heating step)
In this step, the charged particle beam source tip 8 is heated. The heating temperature is equal to or higher than the melting point of the second metal 21. By heating, the second metal 21 covered with the needle-like thin wire 4 is maintained in a molten state. However, in the case of a metal that is easily sublimated, such as platinum (Pt), sublimation proceeds when the high temperature is maintained for a long time, and the second metal 21 adhering to the needle-like thin wire 4 disappears or the periphery of the charged particle beam source 1 This may cause problems such as vapor deposition on the ion source parts. Therefore, this step is kept short.

(FIG. 10: Step S1005: First Charged Particle Release Step)
In this step, a high voltage is applied to the charged particle beam source tip 8 to release charged particles from the tip of the needle-like thin wire 4. For example, by applying a positive voltage of about 5 kV to the charged particle beam source tip 8, positive ions of the second metal 21 are emitted. The purpose of this step is to sharpen the second metal 21 adhering to the tip of the emitter 2 on the cone with electrostatic force, and to reduce the excess second metal 21 accumulated at the tip of the emitter 2 by ion emission. is there.

(FIG. 10: Step S1006: first heating stop step)
In this step, the coated metal on the needle-like thin wire 4 is solidified. If the heating current is stopped in a state where the charged particles are released in step S1005, the heating is stopped and the temperature of the emitter 2 is lowered, and the coating is solidified when the temperature reaches the melting point of the second metal 21 or less. By this step, the coated metal is solidified with a small tip radius of curvature.

(FIG. 10: Step S1007: Voltage stop process)
In this step, the voltage applied to the emitter 2 in order to emit charged particles is stopped.

(FIG. 10: Step S1008: Second heating step)
In this step, the emitter 2 is annealed (annealed) below the melting point of the second metal 21. For example, when the second metal 21 is platinum (Pt), it is heated at a temperature of about 700 ° C. After this step is continued for a predetermined time at a predetermined temperature, the heating current is stopped.

(FIG. 10: Step S1009: Second Charged Particle Release Step)
In this step, charged particles are emitted from the emitter 2 in order to evaluate whether or not the microprojections 25 are sharpened to the atomic level. In the case of emitting electrons, a negative high voltage is applied to the charged particle beam source tip 8. In the case of releasing positive ions, a positive high voltage is applied to the needle-like thin wire 4 while supplying a gas to be ionized around the tip of the emitter 2. In order to generate negative ions, a negative high voltage is applied to the needle-like thin wire 4 while supplying a gas to be ionized around the tip of the emitter 2.

(FIG. 10: Step S1009: Second charged particle emission step: supplement)
Gases introduced when generating ions are hydrogen (H ₂ ), helium (He), neon (Ne), argon (Ar), xenon (Xe), krypton (Kr), oxygen (O ₂ ), nitrogen ( N ₂ ) can be used. Further, when ions are generated, the charged particle beam source 1 may be brought into thermal contact with the cooling device so that gas molecules and atoms can be easily adsorbed to the needle-like thin wires 4. Note that negative ions may be emitted in a very small amount depending on the gas type, or negative ions and electrons may coexist. Therefore, it is preferable to release positive ions when ion emission is desired. Neon is easy to be ionized even when the emitter 2 is at room temperature, which is convenient for evaluating the atomic arrangement at the tip of the emitter 2.

(FIG. 10: Steps S1010 to S1011)
These steps are the same as steps S906 to S907 in FIG.

  As described above, in the sixth embodiment, the manufacturing method of the charged particle beam source 1 has been described in more detail.

  If the tip of the charged particle beam source tip 8 has a desired sharp shape, electrons, positive ions or negative ions can be generated at a lower voltage than before the coating metal is deposited. Therefore, after the first heating stop step (step S1006), it is possible to grasp the sharpened state of the tip of the needle-like thin wire 4 by applying a high voltage to the charged particle beam source tip 8.

  Specifically, a detector (MCP: microchannel plate) is installed at the position of the heating container in FIG. 2, and the emission pattern of electrons, positive ions, or negative ions is observed, and the tip of the needle-like thin wire is observed. The atomic arrangement of the coated metal can be confirmed. Thereby, it can be grasped | ascertained whether the front-end | tip part 25 is sharpened to the monoatomic level.

<Embodiment 7>
FIG. 11 is a configuration diagram of a charged particle beam source manufacturing apparatus 30 that executes the manufacturing method of the charged particle beam source 1 described in the first to sixth embodiments. Hereinafter, each configuration of the charged particle beam source manufacturing apparatus 30 will be described.

  A charged particle beam source tip 8 having a needle-like thin wire 4 whose tip radius of curvature is sharpened to about 50 nm in advance by electropolishing is placed in the vacuum vessel 7, and the inside of the vacuum vessel 7 is maintained in an ultrahigh vacuum state. The charged particle beam source tip 8 can be moved from the outside of the vacuum vessel 7 in the axial direction of the charged particle beam source tip 8 by the tip moving mechanism 44. By using the tip moving mechanism 44, the needle-like thin wires 4 can be brought into contact with or immersed in the coating metal (second metal) 21 in a molten state facing each other.

  Connected to the charged particle beam source tip 8 are a heating power source 39, a high voltage power source 40 for applying a voltage for accelerating charged particles, and an ammeter 41 for measuring a charged particle beam current to be emitted.

  The heating power source 39 is a power source for heating the emitter 2 at a high temperature, and can purify the surface of the emitter 2 by evaporating impurities on the surface by high temperature heating.

  The high voltage power supply 40 is a power supply for applying a high voltage to the emitter 2 to generate an electric field and discharging charged particles from the tip of the emitter 2. In addition, the second metal 21 may accumulate at the tip of the emitter 2 immediately after coating the second metal 21 and the film thickness of the second metal 21 may be excessively thick. Also used to reduce the amount of metal 21. When the ions of the second metal 21 are positive ions, the polarity of the high voltage power supply 40 is positive. For example, if the radius of curvature of the tip to which the second metal 21 is excessively attached is 100 nm, the distance between the extraction electrode 22 and the needle-like thin wire 4 is about 0.5 mm, and the extraction electrode 22 is set to the ground potential, ions are about 5 to 7 kV. Released. In the operation of removing the excessive second metal 21 film, a large current of 100 μA or more is passed.

  The extraction electrode 22 is a conductive flat plate having a hole 26, is arranged so as to face perpendicular to the axis of the needle-like thin wire 4, and has a moving mechanism that can move perpendicularly to the axis of the emitter 2. . The extraction electrode 22 and the hole 26 have the following uses.

(Application 1 of the extraction electrode 22 and the hole 26)
By moving the needle-like thin wire 4 so as to be positioned at the center of the hole 26, the charged particles emitted from the emitter 2 do not directly collide with the extraction electrode 22, so that the secondary particles generated from the extraction electrode 22 ( Secondary electrons, sputtered particles, secondary ions, etc.) do not return to the needle-like thin wires 4. Thereby, the clean state of the tip of the emitter 2 can be maintained.

(Application 2 of the extraction electrode 22 and the hole 26)
By moving the extraction electrode 22 and shielding the heating vessel 33 at the portion without the hole, the evaporation material of the coated metal 21 in the heating vessel 33 is blocked from being attached to the charged particle beam source tip 8 or the like. can do. That is, the extraction electrode 22 also has a use as a shutter.

(Use of extraction electrode 22 and hole 26)
By moving the extraction electrode 22 to a retracted position (a position where the extraction electrode 22 does not contact the extraction electrode 22 even when the emitter 2 is moved up and down), the coated metal 21 can be attached to the needle-like thin wire 4 (emitter before metal attachment).

  The heating container 33 is a container that stores and melts the second metal 21 serving as a coating metal, and is heated by energization from a heating power supply 39 installed outside the vacuum container 7. The heating container 33 may be, for example, a crucible with a built-in heater or a coiled filament heater.

  In order to confirm the formation of the single atom terminal, the charged particles can be actually emitted in the charged particle beam source manufacturing apparatus 30. When electrons are emitted, electrons can be emitted by switching the high-voltage power supply 39 to the negative electrode while the extraction electrode 22 remains at the ground potential and applying a negative high voltage to the emitter 2.

  However, it is not known whether or not the tip of the emitter 2 is in a monoatomic state simply by measuring the emitted current value. Therefore, an MCP (not shown) and a fluorescent plate (not shown) are installed at the position of the heating vessel 33 or between the heating vessel 33 and the extraction electrode 22. Thereby, as explained in the previous embodiment, the sharpened state can be confirmed by observing the atomic arrangement at the tip of the emitter 2.

  When the atomic arrangement at the tip of the emitter 2 is confirmed by emitting ions, an ionized gas (for example, neon, helium, etc.) stored in the cylinder 42 using a gas introduction mechanism installed in the charged particle beam source manufacturing apparatus 30 in advance. , Hydrogen, etc.) are supplied from the nozzle 43 to the periphery of the emitter 2. By applying a high voltage to the emitter 2 in this state, the ionized gas is ionized in a field at a position reflecting the atomic arrangement at the tip of the emitter 2 and emitted as ions. Even in this case, for example, by using an MCP (not shown) and a fluorescent plate (not shown), the atomic arrangement on the surface of the emitter 2 that becomes the starting point of the emitted ions can be visualized. When ions are released in a monoatomic state, one bright spot can be observed stably.

  The configuration of the charged particle beam source manufacturing apparatus 30 has been described in the seventh embodiment.

<Eighth embodiment>
FIG. 12 is a schematic diagram showing a configuration of a charged particle beam apparatus 100 according to Embodiment 8 of the present invention. The charged particle beam apparatus 100 according to the eighth embodiment includes the charged particle beam source 1 manufactured by the charged particle beam source manufacturing method described in any of the first to seventh embodiments. Hereinafter, each configuration of FIG. 4 will be described.

  The charged particle beam 111 emitted from the emitter 2 is focused by the electrostatic lenses 102-1 and 102-2 and irradiated onto the sample 112 on the sample stage 101. The irradiation position of the charged particle beam 111 on the sample 112 is adjusted by deflecting the charged particle beam 111 with the deflectors 103-1 and 103-2.

  Secondary electrons 113 generated from the sample 112 are detected by the secondary electron detector 104, and a secondary electron observation image in which the signal intensity corresponds to the deflection intensity is formed on the display 110. The user can specify the position of the charged particle beam 111 on the screen while viewing the secondary electron observation image using the display device 110.

  The lens system 102 including the electrostatic lenses 102-1 and 102-2, the beam limiting aperture 102-3 and the aligner 102-4 is controlled by the lens system controller 105. The deflection system 103 including the deflectors 103-1 and 103-2 is controlled by the deflection system controller 106. In addition, the code | symbol of the box showing the driver of each part is abbreviate | omitted.

  The tip of the emitter 2 of the charged particle beam source 1 is sharpened to the level of one atom. When electrons are emitted from the emitter 2, the electrons are emitted from this one atom, so that an electron source with high luminance is obtained.

  Even when one atom of the tip 25 is detached unexpectedly, the second metal 21 film adhering to the needle-like thin wire 4 is melted and supplied to the tip 25 by heating the emitter 2. Therefore, the tip 25 can be regenerated to the shape of one atom level any number of times. Thereby, the long-life charged particle beam apparatus 100 can be provided.

  The “charged particle beam optical system” in the eighth embodiment corresponds to the lens system 102 and the deflection system 103.

  In the charged particle beam apparatus 100 according to the eighth embodiment, since electrons are emitted from one atom, the surface of the sample to be observed can be irradiated with an extremely small diameter electron beam. In the observed SEM image, An image with an image resolution of about 0.2 nm is obtained.

  1: charged particle beam source, 2: emitter, 3: extraction electrode, 4: needle-like wire, 5: coated metal, 6: charged particle, 7: vacuum vessel, 8: charged particle beam source tip, 9: filament, 10 : Electrical terminal, 11: Insulator, 21: Second metal, 22: Shutter / extraction electrode, 23: Impurity, 25: Tip, 25a: Microprotrusion, 26: Hole, 27: Ion, 28a, 28b, 28c, 28d: Crystal plane, 30: Charged particle beam source manufacturing apparatus, 33: Heating vessel, 34: Heater, 35: Heating power supply, 38: Linear introduction machine, 39: Heating power supply, 40: High voltage power supply, 41: Ammeter, 42: Gas cylinder, 43: Gas introduction nozzle, 44: Straight line introduction machine, 63: Concave part, 66: Convex part, 66: Concave part, 67: Convex part, 100: Charged particle beam apparatus, 101: Sample stage, 102: Lens system 1 2-1, 102-2: electrostatic lens, 102-3: beam limiting aperture, 102-4: aligner, 103: deflection system, 103-1, 103-2: deflector, 104: secondary electron detector, 105: Lens system controller, 106: Deflection system controller, 110: Display, 111: Charged particle beam, 112: Sample, 113: Secondary electron.

Claims (17)

A method of manufacturing a charged particle beam source that emits charged particles, comprising:
A second metal coating step in which a needle-shaped fine wire made of a sharpened first metal is disposed in a vacuum chamber, and a second metal having a melting point lower than that of the first metal is coated on at least a tip of the needle-shaped thin wire;
The needle-shaped fine wire coated with the second metal is heated to a melting point of the second metal or higher and lower than the melting point of the first metal, and is kept in a molten state, and charged particles are discharged from the tip of the needle-shaped fine wire. A charged particle emission process;
A second metal solidifying step of lowering the temperature of the acicular fine wire below the melting point of the second metal with the charged particles being released;
A charged particle beam source manufacturing method comprising:   The method of manufacturing a charged particle beam source according to claim 1, wherein each of the steps is performed without exposing the needle-like thin line to the atmosphere. In the second metal coating process,
The second metal is melted in the vacuum chamber, and at least the tip of the needle-like thin wire is brought into contact with or immersed in the molten second metal, and the second metal is placed on at least the tip of the needle-like thin wire. The method of manufacturing a charged particle beam source according to claim 1, wherein coating is performed.   2. The method of manufacturing a charged particle beam source according to claim 1, wherein the first metal is a metal having a melting point of 2500 [deg.] C. or higher. The charged particle beam according to claim 1, wherein the first metal is any one of tungsten (W), molybdenum (Mo), rhenium (Re), niobium (Nb), and tantalum (Ta). Source manufacturing method.   The method of manufacturing a charged particle beam source according to claim 1, wherein the second metal is a metal having a melting point of 900 ° C or higher and lower than 2500 ° C. The second metal is gold (Au), silver (Ag), platinum (Pt), iridium (Ir), ruthenium (Ru), palladium (Pd), rhodium (Rh), copper (Cu), nickel (Ni). The method of manufacturing a charged particle beam source according to claim 1, wherein In the second metal coating step,
The difference between the temperature of the needle-like fine wire when the needle-like fine wire is brought into contact with or immersed in the second metal in the molten state and the temperature of the second metal in the molten state is within 50 ° C. A method of manufacturing a charged particle beam source according to claim 3. The charged particle beam source manufacturing method according to claim 1, further comprising a step of providing one or more recesses or protrusions on a side surface of the needle-like thin wire before covering the second metal with the needle-like thin wire. . An emitter in which at least the tip of a needle-shaped thin wire made of a first metal is coated with a second metal;
An extraction electrode that forms an electric field at the tip of the emitter to emit charged particles;
A charged particle beam source comprising:
The emitter is
The needle-shaped fine wire is contacted or immersed in the molten second metal in a vacuum chamber to cover at least the tip of the needle-shaped fine wire with the melted second metal, and the second metal at the tip of the emitter is covered with the second metal. Charged particle beam source characterized by being solidified. An emitter in which at least the tip of a needle-shaped thin wire made of a first metal is coated with a second metal;
An extraction electrode that forms an electric field at the tip of the emitter to emit charged particles;
A charged particle beam source comprising:
The emitter is
A charged particle beam source, wherein one or more concave portions or convex portions are provided on a side surface of the needle-like fine wire, and at least a tip portion of the needle-like fine wire is covered with the second metal.   The charged particle beam source according to claim 10, wherein the tip of the emitter is composed of one atom of the second metal. 11. The charged particle beam source according to claim 10, further comprising a voltage application unit that emits electrons from a tip of the emitter by setting the potential of the emitter to a negative potential with respect to the extraction electrode. A gas supply for supplying a gas to be ionized to the emitter;
A voltage application unit that causes the emitter potential to be positive with respect to the extraction electrode and emits positive ions of the gas from the tip of the emitter;
The charged particle beam source according to claim 10, comprising: The gas is at least one of hydrogen (H ₂ ), helium (He), neon (Ne), argon (Ar), xenon (Xe), krypton (Kr), oxygen (O ₂ ), and nitrogen (N ₂ ). The charged particle beam source according to claim 14, comprising any one of the above.   The charged particle beam source according to claim 14, further comprising a cooling device that cools the emitter. A sample stage on which the sample is placed;
A charged particle beam source according to claim 10;
A charged particle beam optical system that focuses the charged particle beam emitted by the charged particle beam source and focuses the sample on the sample surface;
A detector for detecting secondary particles generated from the sample;
A charged particle beam apparatus comprising:

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