JP2016115684A - Manufacturing method of emitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an emitter which is capable of returning a crystal structure of a head end into an original state with high reproducibility by re-arraying atoms by treatment, and is available continuously for a long time by suppressing rise of an extraction voltage after the treatment.SOLUTION: A manufacturing method of the emitter includes: an electrolytic polishing step S10 for performing electrolytic polishing on a front end portion of an emitter material so as to gradually reduce a diameter towards a front end; a first etching step S20 for etching a processed portion in the emitter material by irradiating the processed portion with charged particle beams, and forming a sharpened part in a pyramidal shape with the front end as an apex; a second etching step S30 for further sharpening the front end by field induction gas etching while observing a crystal structure of the front end in the sharpened part with a field ion microscope, and making the number of atoms forming the head end equal to or less than a fixed number; and a heating step S40 for heating the emitter material to array the atoms forming the head end of the sharpened part in a pyramidal shape.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for manufacturing an emitter used as an emission source that emits electrons, ions, and the like.

Conventionally, for observing a sample such as a semiconductor device, performing various evaluations, analyzing, etc., or taking out a fine thin sample from the sample and then fixing the thin sample to a sample holder to produce a TEM sample A focused ion beam device is known as the device.
This focused ion beam apparatus includes an ion source that generates ions, and the generated ions are then irradiated as a focused ion beam (FIB).

  There are several types of ion sources. For example, plasma ion sources and liquid metal ion sources are known, but a focused ion beam with higher brightness and smaller beam diameter than these ion sources can be generated. A gas field ion source (GFIS: Gas Field Ion Source) is known (see, for example, Patent Document 1).

A gas field ion source includes an emitter whose tip is sharpened at an atomic level, a gas source that supplies a gas such as helium (He) around the emitter, a cooling unit that cools the emitter, and a tip of the emitter And an extraction electrode disposed at a distant position.
In such a configuration, after supplying the gas, when an extraction voltage is applied between the emitter and the extraction electrode and the emitter is cooled, the gas is ionized by ionizing the field by a high electric field at the tip of the emitter, Become. Then, this gas ion is repelled from the emitter held at a positive potential, extracted to the extraction electrode side, and then focused while being moderately accelerated, thereby forming a focused ion beam.

  In particular, ions generated from a gas field ion source have a high luminance, a small light source diameter, and a small energy spread, as described above, so that the sample can be irradiated with a small beam diameter. Therefore, high resolution and fine etching processing during observation are possible.

Japanese Patent Laid-Open No. 7-240165

  By the way, in order to generate a focused ion beam with a small beam diameter, it is preferable that the crystal structure at the tip of the emitter is made into a pyramid and that as few atoms as possible are arranged at the forefront. By doing so, it is possible to locally ionize the gas into gas ions, and thus it is possible to generate a focused ion beam having a small beam diameter. Therefore, it is required that the above-described crystal structure is always stably maintained at the tip of the emitter.

However, the crystal structure at the tip of the emitter is easily broken, and the structure is easily changed from the original state. In such a case, a technique (treatment) for returning the crystal structure of the tip of the emitter to the original state is known.
Specifically, this is a technique in which the tip of the emitter is heated to, for example, about 700 ° C. to 900 ° C., thereby causing rearrangement of atoms and returning the crystal structure to the original state. Therefore, by performing this treatment periodically or as necessary, the atoms are rearranged to return the crystal structure at the tip of the emitter to the original state.

  By the way, as described above, it is ideal for the crystal structure at the tip of the emitter to have atoms arranged accurately in a pyramid shape. In practice, however, atoms are surely arranged in such an ideal pyramid shape. It cannot be said that the technology to arrange them is established. Therefore, the conventional emitter has a structure in which many atoms exist at the leading edge.

  Therefore, even if the treatment is performed and the atoms are rearranged, the number of atoms is large, so reliable reproducibility is not obtained every time, and the crystal structure is often incomplete. The yield of heat regeneration was bad.

In addition, since the number of atoms is large, the heating time for causing rearrangement tends to be long. Therefore, even if rearrangement could be performed, the tip shape of the emitter was easily increased in diameter due to the effect of heating. As a result, as shown in FIG. 19, the optimum voltage value of the extraction voltage applied to the emitter increases every time treatment is performed.
In particular, if the optimum value of the extraction voltage increases, the load applied to the emitter is large, the emitter is easily broken by discharge, etc., and becomes unusable as it approaches the output limit of the extraction voltage of the device. This would shorten the emitter life.

  The present invention has been made in consideration of such circumstances, and the purpose of the present invention is to restore the state-of-the-art crystal structure to its original state with good reproducibility by the rearrangement of atoms by treatment. It is an object of the present invention to provide an emitter manufacturing method capable of suppressing an increase in the optimum value of the extraction voltage later and obtaining an emitter that can be used for a long time.

In order to achieve the above object, the present invention provides the following means.
(1) A method for producing an emitter according to the present invention is a method for producing a sharpened needle-like emitter, wherein the tip of a conductive emitter material is electropolished and gradually reduced in diameter toward the tip. An electropolishing step for processing so as to perform etching processing by irradiating the processed portion of the emitter material with a charged particle beam to form a pyramid-shaped sharpened portion with the tip as a vertex; A second etching step of further sharpening the tip by electric field induced gas etching while observing the crystal structure of the tip at the sharpened portion with a field ion microscope, and reducing the number of atoms constituting the leading edge to a certain number or less; A heating step of heating the emitter material to arrange atoms constituting the tip of the sharpened portion in a pyramid shape.

  According to the method for manufacturing an emitter according to the present invention, first, the tip of the emitter material is subjected to electrolytic polishing so that the diameter thereof is gradually reduced toward the tip. As a result, the tip of the emitter material is, for example, at a tip diameter of at least 100 nm or less and substantially sharpened. Next, the electropolished portion is irradiated with a charged particle beam and further etched to form, for example, a pyramidal sharpened portion with an apex angle of 20 degrees or less. As a result, a pyramid-shaped sharpened portion (for example, a triangular pyramid or a hexagonal pyramid) sharpened in nanometer order can be produced. In particular, since a charged particle beam is used, processing variation can be suppressed, and a sharpened portion can be finely formed into a desired shape.

Next, while observing the crystal structure of the tip at the sharpened portion with a field ion microscope, the tip is further sharpened on an atomic level order by electric field induced gas etching. At this time, since the number of atoms constituting the leading edge decreases as the sharpness is increased, processing is performed until the number of atoms constituting the leading edge becomes a certain number or less (for example, several to several tens) by observation with a field ion microscope. By doing so, the shape of the sharpened portion can be sharpened on the atomic level order. In particular, since the number of atoms constituting the leading edge of the sharpened portion can be reduced to a certain number or less, the leading edge can be configured with a much smaller number of atoms than the conventional one.
Finally, a heating process is performed in which the emitter material is heated to arrange the atoms constituting the tip of the sharpened portion in a pyramid shape. At this time, since the number of atoms constituting the leading edge is smaller than in the past, it is easy to arrange these few atoms in an ideal pyramid shape, for example, sharpening with one or three atoms arranged at the leading edge. Needle-shaped emitters can be obtained.

Therefore, according to the emitter manufactured in this way, electrons and ions can be emitted with a small light source diameter and high brightness. In particular, since the number of atoms constituting the most advanced state is smaller than in the past, a small number of atoms can be rearranged efficiently when heat treatment is performed, and the crystal structure of the original pyramid is reproducible. Can be returned to. Therefore, the yield of heating regeneration can be improved.
In addition, since a small number of atoms can be rearranged efficiently, the heating time can be shortened and the increase in the diameter of the tip of the emitter can be suppressed. Therefore, an increase in the optimum value of the extraction voltage after the treatment can be suppressed, and the lifetime of the emitter can be extended and it can be used for a long time.

(2) In the method for manufacturing an emitter according to the present invention, it is preferable to perform etching so that the apex angle of the sharpened portion is 10 degrees or less by irradiation with a focused ion beam in the first etching step.

  In this case, using a focused ion beam suitable for microfabrication, etching is performed so that the apex angle is 10 degrees or less, so that a sharpened pyramid sharpened portion can be stably formed. Can do. Therefore, the number of atoms constituting the most advanced state can be further reduced by the second etching process performed thereafter, and the above-described operation and effect can be more remarkably achieved.

(3) In the method for manufacturing an emitter according to the present invention, tungsten is preferably used as the emitter material.
(4) In the emitter manufacturing method according to the present invention, iridium is preferably used as the emitter material.

  In this case, since tungsten having a body-centered cubic structure or iridium having a face-centered cubic structure is used as the emitter material, atoms constituting the tip of the sharpened portion can be easily arranged in an ideal pyramid shape. In addition, since tungsten or iridium having a high melting point and hardness and chemically stable is used, a high-quality emitter can be obtained.

  According to the method for manufacturing an emitter according to the present invention, the state-of-the-art crystal structure can be restored to its original state with good reproducibility by rearranging atoms by treatment, and the optimum value of the extraction voltage after treatment is increased. Can be suppressed and can be used for a long time.

It is a whole lineblock diagram showing an embodiment of a focused ion beam device provided with an emitter concerning the present invention. It is an enlarged view of the emitter shown in FIG. FIG. 3 is an enlarged view of the tip of the emitter shown in FIG. 2 at an atomic level. FIG. 3 is an enlarged view of the tip of the emitter shown in FIG. 2 at an atomic level. 3 is a flowchart of a method for manufacturing the emitter shown in FIG. It is a figure which shows 1 process at the time of producing an emitter, Comprising: It is a figure which shows the state which has electropolished the front-end | tip part of the emitter raw material. It is an enlarged view of the front-end | tip part of the emitter raw material processed by the electrolytic polishing process shown in FIG. It is an enlarged view of A part shown in FIG. It is a figure which shows the state which has etched the electrolytic processing part by FIB after the electrolytic polishing process. It is the figure which showed the flow until it forms the sharpened sharpened part by the etching process by FIB shown in FIG. FIG. 10 is an enlarged view of a sharpened portion formed at the tip of the emitter material by the etching process using FIB shown in FIG. 9. It is a figure which shows the state which set the emitter raw material shown in FIG. 11 to the electrolytic ion microscope. It is a state-of-the-art FIM image at the sharpened portion of the emitter material, observed by an electrolytic ion microscope. It is a FIM image when the number of state-of-the-art atoms in the sharp part of the emitter material is reduced by electric field induced gas etching. It is a FIM image when the number of state-of-the-art atoms in the sharp part of the emitter material is further reduced by electric field induced gas etching. FIG. 4 is an FIM image when the state-of-the-art crystal structure in the sharpened portion of the emitter material is shown in FIG. FIG. 4 is an FIM image in the case where the most advanced crystal structure in the sharpened portion of the emitter material is shown in FIG. It is the figure which showed the relationship between the frequency | count of treatment and extraction voltage value in the emitter concerning this invention. It is the figure which showed the relationship between the frequency | count of treatment and extraction voltage value in the conventional emitter.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
In this embodiment, a gas field ion source (GFIS: Gas Field Ion Source) is configured and an emitter used as an ion beam emission source will be described as an example.

  First, a focused ion beam apparatus including a focused ion beam column equipped with the gas field ion source will be briefly described.

<Focused ion beam device>
As shown in FIG. 1, the focused ion beam apparatus 1 includes a focused ion beam column 2 for irradiating a sample S placed on a stage (not shown) with a focused ion beam (FIB), and a focused ion beam. (FIB) detector 4 for detecting secondary charged particles generated by irradiation, gas gun 5 for supplying a source gas for forming a deposition film, and image data based on the detected secondary charged particles And a control unit 7 for displaying the image data on a display unit (not shown).

  The stage operates based on an instruction from the control unit 7, and can be displaced, for example, in five axes. Thereby, it is possible to irradiate the focused ion beam (FIB) toward a desired position by appropriately displacing the stage about five axes. This stage is housed in a vacuum chamber (not shown), and focused ion beam (FIB) irradiation, source gas supply, and the like are performed in the vacuum chamber.

  The focused ion beam column 2 includes an emitter 10, a gas source 11, a cooling unit 12, a heating unit 13, an extraction electrode 14, an extraction power source unit 15, and a beam optical system 16.

  The emitter 10 is a needle-like conductive member having a sharpened tip as shown in FIG. 2, and is an emission source that emits an ion beam. The emitter 10 is manufactured by a manufacturing method to be described later, and the tip thereof is sharpened on the atomic level order. Specifically, the crystal structure is configured to be a pyramid. For example, the state in which 3 atoms A1 are arranged at the forefront as shown in FIG. 3, or 1 atom A2 at the foremost as shown in FIG. Are arranged.

  As shown in FIG. 1, the emitter 10 is supported in a state of being housed in an ion generation chamber 20 whose inside is maintained in a high vacuum state. The gas source 11 can supply a small amount of gas (for example, helium (He) gas) G around the emitter 10 via a gas introduction tube 11 a communicating with the ion generation chamber 20. Yes. The heating unit 13 locally heats the tip of the emitter 10 and is, for example, a filament. The heating unit 13 locally heats the tip of the emitter 10 to a predetermined temperature by a current from a current source 13a that operates according to an instruction from the control unit 7, and causes the atoms constituting the emitter 10 to rearrange. I am doing.

  The extraction electrode 14 is disposed in the opening of the ion generation chamber 20 in a state of being separated from the tip of the emitter 10. The extraction electrode 14 has an opening 14 a at a position facing the tip of the emitter 10. The extraction power supply unit 15 is an electrode that applies an extraction voltage between the extraction electrode 14 and the emitter 10. The extraction power supply unit 15 plays the role of extracting the gas ions to the extraction electrode 14 side after applying the extraction voltage to ionize the gas G at the forefront of the emitter 10 to gas ions.

The cooling unit 12 cools the emitter 10 with a refrigerant such as liquid helium or liquid nitrogen. In the present embodiment, the cooling unit 12 is designed to cool the entire space E including the extraction electrode 14 as illustrated. . However, it is sufficient that at least the emitter 10 is cooled. Moreover, you may use a refrigerator as a cooling method.
By the way, the emitter 10, the gas source 11, the heating unit 13, the extraction electrode 14, the extraction power source unit 15, and the ion generation chamber 20 described above constitute a gas field ionization type ion source 21 that generates gas ions from the gas G. .

  A cathode 22 having a ground potential is provided below the extraction electrode 14. An acceleration voltage is applied between the cathode 22 and the emitter 10 from an acceleration power supply unit 23, and energy is applied to the extracted gas ions to accelerate them into an ion beam. A first aperture 24 that narrows the ion beam is provided below the cathode 22. A condenser lens 25 is provided below the first aperture 24 to focus the ion beam into a focused ion beam (FIB).

  Below the condenser lens 25, there is provided a second aperture 26 that is movable in the horizontal direction and further narrows the focused ion beam (FIB). A deflector 27 that scans the focused ion beam (FIB) on the sample S is provided below the second aperture 26. Below the deflector 27, an objective lens 28 for focusing the focused ion beam (FIB) on the sample S is provided.

  The cathode 22, the acceleration power source 23, the first aperture 24, the condenser lens 25, the second aperture 26, the deflector 27, and the objective lens 28 described above, after the extracted gas ions are converted into a focused ion beam (FIB). The beam optical system 16 for irradiating the sample S is configured. Although not shown, the astigmatism corrector and the beam position adjusting mechanism used in the conventional focused ion beam apparatus are also included in the beam optical diameter.

The detector 4 detects secondary charged particles such as secondary electrons, secondary ions, reflected ions and scattered ions emitted from the sample S when irradiated with a focused ion beam (FIB), and a control unit. 7 is output.
The gas gun 5 can supply a compound gas containing a material (for example, phenanthrene, platinum, carbon, tungsten, or the like) as a raw material for the deposition film as a raw material gas. This source gas is decomposed by irradiation with a focused ion beam (FIB) and secondary charged particles generated thereby, and is separated into a gas component and a solid component. A deposition component is formed by depositing a solid component of the two separated components.

  The gas gun 5 can be made of a substance that selectively accelerates etching (for example, xenon fluoride, chlorine, iodine, water). For example, when the sample S is Si-based, xenon fluoride is used, and when the sample S is organic-based, water is used. Moreover, etching of a specific material can be advanced by irradiating simultaneously with an ion beam.

  The control unit 7 comprehensively controls the above-described components, and can appropriately change the extraction voltage, the acceleration voltage, the beam current, and the like. Therefore, not only can the beam diameter of the focused ion beam (FIB) be adjusted freely to obtain an observation image, but also the sample S can be locally etched (roughened, finished, etc.), etc. Yes.

The control unit 7 converts the secondary charged particles detected by the detector 4 into a luminance signal to generate observation image data, and then causes the display unit to output the observation image based on the observation image data. Yes. Thereby, it is possible to confirm the observation image via the display unit.
Furthermore, an input unit (not shown) that can be input by an operator is connected to the control unit 7, and each component is controlled based on a signal input by the input unit. Therefore, the operator observes the desired region by irradiating the focused ion beam (FIB) via the input unit, performs etching processing on the desired region, or supplies the source gas to the desired region. It is possible to deposit a deposition film by irradiating a beam (FIB).

<Method of manufacturing emitter>
Next, a method for manufacturing the emitter 10 described above will be described with reference to the flowchart shown in FIG.

First, an electrolytic polishing process (S10) is performed in which the tip portion of the emitter material is electrolytically polished so that the diameter gradually decreases toward the tip.
Specifically, as shown in FIG. 6, first, as the emitter material 30, for example, a wire made of a tungsten single crystal having a crystal plane (111) plane in the axial direction is prepared. It is held by a holding tool 32 via a fixing wire 31.
For example, a wire having a diameter of about 0.1 to 0.3 mm and a length of several mm is used as the emitter material 30. Further, the fixing wire 31 has a role of heating the emitter material 30 by energization in addition to supporting the emitter material 30.

Then, the tip of the emitter material 30 held by the holder 32 is immersed in the polishing solution W stored in the polishing tank 33. Examples of the polishing solution W include a 3 mol / L KOH (potassium hydroxide) solution. A cathode 34 is disposed in the polishing tank 33.
Then, an etching voltage (for example, DC 3 V) is applied between the emitter material 30 and the cathode 34 by a voltage application unit 35 for a predetermined etching time (for example, around 400 seconds), so that the tip of the emitter material 30 is electrolyzed. Polishing is performed.

  Thereby, as shown in FIG. 7, the front-end | tip part of the emitter raw material 30 can be substantially sharpened so that a diameter may be gradually reduced toward a front-end | tip. At this time, as shown in FIG. 8, the electrolytic polishing is performed until the tip diameter R is 100 nm or less, more specifically 30 to 80 nm, and the tip apex angle θ <b> 1 is about 10 to 30 degrees.

Next, after the electrolytic polishing step (S10) is completed, as shown in FIG. 9, a first etching step (S20) is performed in which a focused ion beam (FIB) is irradiated to the electrolytic polishing processed portion to perform etching processing. Do.
Specifically, as shown in FIGS. 9 and 10, focused ions are rotated while the emitter material 30 is rotated about its axis O intermittently over a processing region H of, for example, 50 μm from the tip of the electropolishing portion. Beam (FIB) is irradiated to form a pyramid-shaped sharpened portion 40. In the illustrated example, the hexagonal pyramid sharpened portion 40 is formed by processing so that six pyramidal surfaces 41 appear by a focused ion beam (FIB).
At this time, as shown in FIG. 11, the sharpened portion 40 is finished so that the tip of the sharpened portion 40 is the apex, and the apex angle θ <b> 2 is 20 degrees or less. In the illustrated example, the apex angle θ2 is finished to about 10 degrees.

  By this first etching step (S20), a hexagonal pyramid sharpened portion 40 that is extremely sharpened in the order of nanometers can be produced. In particular, since a focused ion beam (FIB) is used, processing variations can be suppressed, and the sharpened portion 40 can be finely formed into a desired shape.

  Next, after the first etching step (S20) is completed, the tip is further sharpened on the atomic level by field-induced gas etching while observing the crystal structure at the tip of the sharpened portion 40 with a field ion microscope. A second etching step (S30) is performed.

This process will be described in detail.
First, as shown in FIG. 12, the field ion microscope (FIM) 50 includes a vacuum chamber (not shown) into which various gases are introduced at a predetermined pressure, and a sharpened portion of the emitter material 30 in the vacuum chamber. An MCP (microchannel plate) 51 arranged at a distance from 40, a fluorescent screen 52 that displays an FIM image (field ion image) of the tip of the sharpened portion 40 amplified by the MCP 51, and an emitter material 30. And a heating unit 53 such as a heater for heating.
In FIG. 12, the crystal structure at the tip 40 of the emitter material 30 is shown.

  In the field ion microscope 50 configured as described above, when a high voltage is applied to the emitter material 30 with an inert gas such as helium gas (He) being introduced into the vacuum chamber, the helium gas causes the tip of the sharpened portion 40 to move. In the vicinity of the constituent atoms, it is ionized by a strong electric field and moves to the MCP 51 side according to the lines of electric force. Then, the helium ions are converted into electrons by the MCP 51, and after being amplified, enter the fluorescent screen 52. Thereby, as shown in FIG. 13, the FIM image of the front-end | tip of the sharpened part 40 can be projected on the fluorescent screen 52, and the crystal structure can be confirmed.

Here, during the above observation, when a gas mixture (not shown) containing oxygen and / or nitrogen in addition to helium gas is introduced into the vacuum chamber, etching is performed by removing the tungsten atoms from the gas mixture. Electric field induced gas etching can be performed.
Therefore, by performing this electric field induced gas etching process, the tip of the sharpened portion 40 can be gradually cut and sharpened on the atomic level order. At this time, since the number of atoms constituting the leading edge decreases as the sharpening is performed, the bright spots of the FIM image gradually decrease with time as shown in FIG.

  Then, by observation with the field ion microscope 50, as shown in FIG. 15, processing is performed until the number of atoms (the number of bright spots) constituting the leading edge becomes a certain number or less (for example, several to several tens). Thereby, the shape of the sharpened portion 40 can be sharpened on the atomic level order. In particular, since the number of atoms constituting the leading edge of the sharpened portion 40 can be set to a certain number or less, the leading edge can be configured with a much smaller number of atoms than the conventional one.

Next, after the second etching step (S30) is completed, the emitter material 30 is heated to perform a heating step (S40) in which atoms constituting the tip of the sharpened portion 40 are arranged in a pyramid shape.
In the present embodiment, this step is performed while the emitter material 30 is set on the field ion microscope 50. Specifically, after the helium gas and the mixed gas are discharged from the vacuum chamber and voltage application to the emitter material 30 is stopped, the emitter material 30 is heated by the heating unit 53 at a temperature of about 700 ° C. for about 5 minutes, for example. To do.

  Thereby, arrangement of atoms can be performed. In particular, since the number of atoms constituting the state of the art is smaller than in the prior art, these few atoms can be arranged in an ideal pyramid shape, and as shown in FIGS. 3 and 4, for example, 3 atoms A1 or 1 atom A2 The crystal structure can be arranged at the forefront. As a result, the needle-like emitter 10 shown in FIG. 2 in which the most advanced atoms have such a crystal structure and are sharpened on the atomic level order can be manufactured.

  After this heating step (S40), helium gas is again introduced into the vacuum chamber, and then a voltage is applied to the emitter 10 to observe an FIM image. As shown in FIGS. Alternatively, one bright spot can be observed, and it can be confirmed that the crystal structure has three atoms A1 or one atom A2 arranged at the forefront.

  According to the gas field ionization ion source 21 including the emitter 10 manufactured as described above, an ion beam can be emitted with a small light source diameter and high brightness. Therefore, when the sample S is observed using the focused ion beam (FIB) using this ion beam, the sample S can be observed with high resolution, and when the sample S is processed, it is very fine and highly accurate. Can be processed.

  Further, when the crystal structure of the emitter 10 changes with the use of the gas field ion source 21, the treatment by heating is performed to rearrange the atoms. According to the emitter 10 of the present embodiment, As described above, since the number of atoms constituting the leading edge is smaller than that of the prior art, these small number of atoms can be rearranged efficiently. Therefore, the crystal structure can be returned to the original pyramid shape with good reproducibility. Therefore, the yield of heating regeneration can be improved.

  In addition, since a small number of atoms can be rearranged efficiently, the heating time can be shortened, and the increase in the diameter of the tip of the emitter 10 can be suppressed. Therefore, as shown by the solid line in FIG. 18, an increase in the optimum value of the extraction voltage after the treatment can be suppressed and the optimum value can be made substantially constant as compared with the conventional emitter indicated by the dotted line. As a result, the lifetime of the emitter 10 can be extended and can be used for a long time.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above embodiment, the emitter 10 for the gas field ion source 21 has been described. However, the present invention is not limited to this case. For example, the emitter 10 is an emitter used as an emission source for emitting electrons into an electron beam. Also good.

  In the first etching step (S20), the focused ion beam (FIB) is irradiated to perform the etching process. However, the etching process is not limited to the focused ion beam, and any charged particle beam may be used. For example, etching may be performed using an electron beam or the like. Further, the sharpened portion 40 is formed in a hexagonal pyramid shape, but may be a pyramid shape, and may be formed in, for example, a triangular pyramid shape, a 12 pyramid shape, a 24 pyramid shape, or a 36 pyramid shape. Even in these cases, the sharpened portion 40 sharpened to the nanometer order can be obtained, and the number of atoms constituting the leading edge can be reduced by the second etching step (S30) performed thereafter. .

  Further, in the heating step (S40), the emitter material 30 was heated using the field ion microscope 50 while being set in the field ion microscope 50. For example, after the second etching step (S30), the emitter material 30 is You may set to the gas field ionization type ion source 21, and may perform a heating process (S40). In this case, the gas field ion source 21 can be operated immediately after the heating step (S40).

Further, although tungsten is used as the material of the emitter material 30, it is not limited to this material. However, by using tungsten having a body-centered cubic structure, it is easy to arrange the atoms constituting the tip of the sharpened portion 40 in an ideal pyramid shape. In addition, it is more preferable to use tungsten having a high melting point and hardness and chemically stable, since it is easy to obtain a high-quality emitter 10.
Further, iridium may be used instead of tungsten, and even in this case, the same effect as that obtained when tungsten is used can be obtained.

DESCRIPTION OF SYMBOLS 10 ... Emitter 40 ... Sharp point S10 ... Electropolishing process S20 ... 1st etching process S30 ... 2nd etching process S40 ... Heating process

Claims (3)

A method of making a sharpened needle-like emitter,
While observing the crystal structure at the tip of the sharpened portion of the emitter material with a field ion microscope, the tip is further sharpened by electric field-induced gas etching, and the number of atoms constituting the leading edge is reduced to a certain number or less. ,
And a heating step of heating the emitter material to arrange atoms constituting the tip of the sharpened portion in a pyramid shape. The method of manufacturing an emitter according to claim 1.
A method for manufacturing an emitter, wherein tungsten is used as the emitter material. The method of manufacturing an emitter according to claim 1.
A method for manufacturing an emitter, wherein iridium is used as the emitter material.