JP5071699B2 - Apparatus for local coating of high quantum efficiency material on cathode tip of photocathode type electron beam source - Google Patents

Description

  The invention of this application relates to a device for locally coating a high quantum efficiency material on the cathode tip of a photocathode type electron beam source. More specifically, the invention of this application provides an electron beam source capable of coating a high-efficiency material on a limited minute region of the cathode tip and improving the brightness and coherence of the generated electron beam. The present invention relates to a device for locally coating a high quantum efficiency material on the cathode tip of a photocathode electron beam source.

  In the specification of this application, “local” means a limited minute region of the cathode tip of the photocathode type electron beam source.

  Conventionally, field emission type electron beam sources and thermionic emission type electron beam sources have been generally used as electron beam sources for electron microscopes, electron beam accelerators and X-ray generators. The radiation source is used in various fields as an electron beam source having the highest luminance today. However, even in an electron microscope equipped with a field emission electron beam source that is the electron beam source with the highest luminance, the total current of electrons that are practically emitted at present is only about 1 μA.

  By the way, in an optical microscope, since spherical aberration can be completely removed by combining a convex lens and a concave lens, the image resolution thereof is about the wavelength of visible light, which is a fundamental resolution. On the other hand, a transmission electron microscope (TEM) is impossible in principle to produce a practical magnetic concave lens. Therefore, spherical aberration cannot be removed, and the image resolution is the wavelength of electrons (the fundamental resolution). It is 100 times lower than that at 200 keV (0.0251 angstrom), and only has an image resolution equivalent to that of a magnifying glass in an optical microscope. Even if the electron voltage is shortened by setting the TEM acceleration voltage from 200 kV to 1000 kV, the improvement in image resolution is only about 10%.

  However, if an electron beam source with extremely high brightness is used for the TEM and a good quality hologram is obtained, the spherical aberration of the hologram can be completely removed by combining an optical convex lens and concave lens in the reproduction from the hologram to the image. Thus, the image can be reproduced, and the resolution of the TEM can be improved to a theoretical resolution that is 100 times or more the current resolution. This is shortly after the TEM was invented. Although it is a method proposed by Gabor, even the field emission type electron beam source having the highest luminance and coherence at present is not sufficiently effective in improving the resolution because the luminance is still insufficient.

  Therefore, a photocathode type electron beam source has attracted attention as a new electron beam source. The photocathode type electron beam source uses a photoelectric effect, and a cathode covered with a substance having a high quantum efficiency (ratio of the number of photoelectrons emitted by the photoelectric effect of one photon). On the other hand, it can be used as an electron beam source by emitting light such as laser light and emitting photoelectrons.

  Here, in FIGS. 1A, 1B, and 1C, for comparing the brightness of electron beams from a thermionic emission electron beam source, a field emission electron beam source, and a photocathode electron beam source, respectively. Figure 6 shows how the electron beam is focused. FIGS. 2A and 2B schematically show an outline of an electron beam focusing electrode in a thermionic emission electron beam source and a field emission electron beam source, respectively. As shown in FIG. 1A, the brightness β of the electron beam is expressed as follows: β = I / (S · ω).

  As shown in FIG. 1, in the electron beam sources other than the photocathode type electron beam source, the electron beam diverges once and then converges, so that the solid angle ω is increased even if the tip portion is reduced. On the other hand, in the photocathode type electron beam source, if the laser irradiation area is smaller than the area of the cathode tip, there is no divergence of the electron beam (electrons are in the normal direction (electric field direction) of the surface of the tip. The solid angle ω can be reduced. This is because, in practical use, the photocathode type electron beam source can emit 10,000 times more electrons (current) than other types of electron beam sources. It is expected to be an electron beam source with a brightness much higher than that of the radiation source.

Even if a normal metal is coated on the cathode tip of a photocathode type electron beam source and irradiated with laser light, the emission efficiency (quantum efficiency) of photoelectrons is higher than that of a high quantum efficiency material such as Cs ₃ Sb.
Is less than 1 / 1,000,000 and is negligibly small.

By the way, a substance with high quantum efficiency represented by Cs ₃ Sb, which is the most important element in the photocathode type electron beam source, is chemically extremely active, and its quantum efficiency decreases with time when it reacts with a small amount of oxygen. It is known that this tendency becomes more pronounced as the temperature of the high quantum efficiency material increases. For this reason, a high quantum efficiency substance is sealed in a glass tube and irradiated with weak light so that the temperature does not rise. Therefore, in the conventional photocathode electron beam source in which the cathode tip is coated with a high quantum efficiency material, the total amount of emitted electrons is insufficient, its luminance is suppressed, and it can be used only in a glass tube. There wasn't.

  In order to solve these problems, the inventor of the present invention (Takayoshi Kimoto) proposed a novel photocathode-type electron beam source and a method for producing the same in Patent Document 1 and Patent Document 2 (Split Application of Patent Document 1). And a method of coating high quantum efficiency material on the electron beam source was proposed.

In Patent Document 1, an n-type semiconductor and a p-type semiconductor having high Peltier cooling efficiency (n-type Bi ₂ Te in FIG. 3) are used in the cathode unit (100) to cool the cathode tip as shown in FIG. ₃ (101) and p-type Bi ₂ Te ₃ (102) are directly joined to form a cathode (103), which is joined to a cathode substrate (104) having high thermal conductivity and electrical conductivity. Has been. The n-type Bi ₂ Te ₃ (101) and the p-type Bi ₂ Te ₃ (102) are joined via the cathode terminal (105) and the cathode substrate (104) of the cathode unit (100) so that the endothermic surface is formed. A current is applied to locally cool the cathode tip (106). As a result, the cooling efficiency is much higher than that of cooling the cathode tip only by heat conduction, and the heat input at the cathode tip irradiated with the laser can be more effectively removed. The cathode unit (100) was handled with an electron beam source with a gloved inert working cover attached to prevent a decrease in quantum efficiency due to exposure to oxygen. Note that (107) is a reinforcing insulator, and (108) is Cs ₃ Sb, which is a high quantum efficiency material.

Further, in Patent Document 1 and Patent Document 2, coating of a high quantum efficiency substance on the cathode tip of a photocathode-type electron beam source is performed in a coating apparatus to which a work cover in an inert gas with a glove is attached. It prevents a decrease in quantum efficiency due to exposure to oxygen. That is, in a coating apparatus to which a work cover in an inert gas with a glove is attached, after the high quantum efficiency substance is coated on the cathode tip of the cathode unit in a vacuum state, the vacuum exhaust is stopped and the inside of the coating apparatus is stopped. And the inside of the inert gas working cover is filled to the atmospheric pressure with an inert gas of ultra high purity, and the gloves of the inert gas working cover are made usable. The container was confined with an ultrapure inert gas in an airtight container, and then the airtight container was removed from the coating apparatus. FIG. 4 shows vapor deposition on the cathode tip of the cathode unit in the vapor deposition apparatus and electron beam generator that can use the glove of the work cover in the inert gas, removal from the vapor deposition apparatus of the cathode unit, electron beam of the vapor deposited cathode unit A series of work flow of installation to the generator and operation of the electron beam generator is shown in an easy-to-understand manner.
FIG. 5 is an enlarged view of the work cover for inert gas in FIG. FIG. 6 shows a state in which the entire cathode unit is confined in an airtight container. The names of the respective symbols in FIGS. 4 to 6 are listed in the description of the symbols in the brief description column of the drawings of the specification of this application.

  As described above, the problems of the prior art have been solved. However, since the substance with high Peltier cooling efficiency used for the cathode tip is generally brittle, it is difficult to sharpen or break when external force is applied. There was a problem to be solved such as the possibility of reaching

  Therefore, the inventors of the invention of this application (Takayoshi Kimoto) proposed a cooled high quantum efficiency photocathode-type cathode for an electron beam source in Patent Document 3 in which these problems are improved.

FIG. 7 shows a cathode for a photocathode-type electron beam source disclosed in Patent Document 3. FIG. 7A is an overall view of a cathode unit (110) used for a photocathode type electron beam source, and FIG. 7B is a schematic diagram of the cathode (111) and cathode substrate (112) of the cathode unit (110). FIG. FIG. 7 (c) is a diagram showing these modifications, and FIG. 7 (d) is an enlarged view of the cathode tip (115). As shown in FIG. 7B, n-type Bi ₂ Te ₃ (113) and p-type Bi ₂ Te ₃ (114) are joined to two copper cathode substrates (112) using solder. Further, the cathode tip portion (115) made of copper, which is a material having high thermal conductivity and electrical conductivity, is used for each of n-type Bi ₂ Te ₃ (113) and p-type Bi ₂ Te ₃ (114). Are joined. The tip surface of the cathode tip (115) is slightly concave, and the concave surface is coated with Cs ₃ Sb (116), which is a high quantum efficiency material. In such a configuration, the materials (113) and (114) exhibiting the Peltier effect are not in contact with each other, and have a high thermal conductivity and electrical conductivity, and can be easily sharpened with a cathode tip (115). Therefore, the problem remaining in Patent Document 1 has been solved.
JP 2003-92077 A (page 6-7, FIG. 6; page 5-6, FIG. 1) Japanese Patent Laid-Open No. 2004-22177 (page 4-5, FIG. 1) JP 2003-346691 A (page 7, FIG. 1)

  However, the above-mentioned cooling type high quantum efficiency photocathode type electron beam source electrode is utilized in electron beam sources for electron microscopes such as TEM, accelerators, X-ray generators, and the performance is dramatically improved. In order to make this happen, there were the following problems to be solved.

  That is, the laser beam emitted to the cathode tip by the photocathode electron beam source cannot be made thinner than the wavelength of visible light due to quantum mechanical restrictions. Further, since the cathode tip must be separated from the converging optical lens to some extent due to geometric restrictions, the beam diameter of the laser light becomes larger than the above limit value. Furthermore, since the sharpened tip of the cathode is coated with a high quantum efficiency material on its entirety by vapor deposition, electrons are emitted from a laser irradiation region having a certain extent, and the brightness can be increased. However, there was a limitation in increasing the coherence of the electron beam.

  The invention of this application has been made in view of the actual state of the prior art, and both the brightness and the coherence are remarkably high, and an electron beam source for an electron microscope such as a TEM, an accelerator, an X-ray generator, etc. Provided is a device for locally coating a high quantum efficiency material on the cathode tip of a photocathode type electron beam source that realizes a photocathode type electron beam source capable of dramatically improving the performance of the photocathode type. This is the issue.

In order to solve the above problems, the invention of this application firstly, on the surface of the cathode tip portion of the photocathode type electron beam source of the laser irradiation type from the side where electrons are emitted from the coated high quantum efficiency material. In an apparatus for coating a high quantum efficiency material, a coating area on the cathode tip surface between the tip surface of the cathode having a sharp tip and the emission source from which the constituent material of the high quantum efficiency material coating is emitted A diaphragm having a minute hole for limiting the flow rate is arranged in a non-contact manner on the cathode tip surface, a plurality of constituent materials are attached at the same position to form a high quantum efficiency material , and the cathode tip is negative with respect to the ground. A voltage can be applied, and comprises a Faraday cup and an optical fiber for irradiating a laser beam for causing an external photoelectric effect on the cathode tip coated with a high quantum efficiency material from the center of the bottom of the Faraday cup, To irradiate the cathode tip with laser light after the coating of the pole tip, measure the electron beam emitted from the cathode tip by the external photoelectric effect as a current value, and investigate the coating state based on the result A coated high quantum efficiency material comprising a movable coating state inspection means and a deflecting means for deflecting a traveling direction of an electron beam emitted from a cathode tip near the entrance of the Faraday cup Provided is a local coating apparatus of a high quantum efficiency material on the cathode tip of a photocathode electron beam source of a laser irradiation system from the side from which electrons are emitted.

  According to a second aspect of the present invention, there is provided a local coating apparatus according to the first invention, wherein the coating apparatus is a vacuum deposition apparatus.

  According to a third aspect of the present invention, there is provided the local coating apparatus according to the first or second aspect of the present invention, further comprising a diaphragm heating means for heating the diaphragm.

  According to a fourth aspect of the present invention, there is provided the local coating apparatus according to the third invention, wherein the aperture heating means is a combination of a current heating means and a laser heating means via an optical fiber.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, a plurality of emission sources are provided, these emission sources are mounted on the mounting member, and the center of the cathode tip and the aperture hole There is provided a local coating apparatus characterized in that a mounting member is movable so that an axis connecting with a center is within a geometric range in which a coating constituent material is released from a release source.

  According to a sixth aspect of the present invention, there is provided the local coating apparatus according to the fifth aspect, wherein a plate for shielding radiant heat is provided between the plurality of emission sources on the mounting member.

  According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the invention, the insulating plate for shielding the radiant heat has an opening through which the covering material is emitted on the emission source. A local coating device is provided.

  According to an eighth aspect of the present invention, in any one of the first to seventh aspects of the present invention, an insulating cathode unit mounting base for mounting a cathode unit in which a cathode is incorporated and mounted on a photocathode type electron beam source is provided. There is provided a local coating apparatus characterized in that a diaphragm unit for fixing and holding the base plate is fixed to a recessed opening of an insulating cathode unit mounting base.

  Ninthly, in the eighth invention, the position of the aperture hole fixed to the aperture unit can be adjusted within the recess opening of the insulating cathode unit mounting base, Provided is a local coating apparatus characterized by being able to perform axial alignment with the aperture hole center.

  According to a tenth aspect of the present invention, in the first to ninth inventions, the diaphragm has a sufficient mechanical strength, and one or more fine holes are formed using a focused ion beam, electric field polishing or electric discharge machining. Provided is a local coating device characterized by being opened two or more.

  Eleventhly, in the first to ninth inventions described above, the focused ion beam can be arbitrarily controlled by computer control of the scanning electrode plate in the diaphragm having a recess of a required size formed in the central portion of the diaphragm. There is provided a local coating apparatus characterized in that one or two or more fine holes having a shape of 1 are formed.

According to a twelfth aspect, in any one of the first to eleventh inventions, a cathode tip portion of a cathode bonded with a combination of substances having a high Peltier cooling effect is covered, and a power source is provided for supplying current to the cathode. The present invention provides a local coating apparatus characterized in that heating and cooling of the cathode tip can be selected by selecting the direction in which current flows.

  Further, in the thirteenth aspect, in the twelfth aspect of the invention, there is provided an energization heating means for heating the cathode tip, and a current is passed through the cathode in a direction in which the cathode tip is heated. There is provided a local coating apparatus characterized in that the cathode tip is heated by the combined use with heating by.

  Fourteenth, in the twelfth invention, has a combination of a water-cooled metal plate and a Peltier cooling thermo module for cooling the cathode tip, and cooling by this combination and cooling of the cathode tip to the cathode. The local coating device is characterized in that the tip of the cathode is cooled by the combined use of cooling by passing an electric current in the direction to be applied.

  According to a fifteenth aspect, in any one of the first to fourteenth aspects, an impurity other than the coating constituent material can be prevented from reaching the cathode tip and the emission source from the emission source. There is provided a local coating apparatus characterized by having a movable mask.

Further, in a sixteenth aspect of the present invention , in any one of the first to fifteenth inventions , a laser light focusing lens for causing an external photoelectric effect is provided near the tip of an optical fiber attached to a Faraday cup. Providing equipment.

According to the invention of this application, since the above configuration is adopted, the following remarkable effects can be obtained.
1) The coherence of an electron beam generated from a photocathode type electron beam source can be improved to be equal to or higher than that of a field emission type electron beam source.
2) The brightness of the laser beam is higher at the center, and the open solid angle (ω) of the electron beam at the crossover position is reduced, so that the brightness of the generated electron beam is improved and a field emission electron beam is obtained. Much higher than the source.
3) Since the region covered with the high quantum efficiency material can be made free, the cross section of the generated electron beam can be made free. This is not possible with other electron beam sources and can lead to unexpected scientific progress.
4) By making the range covered with the high quantum efficiency material so small that the change in luminance of the laser beam is not within the range, the luminance of the electron beam can be made constant in the cross section. This is also impossible with other electron beam sources.
5) The coating efficiency of the high quantum efficiency material on the cathode tip can be improved.
6) Not only is the TEM resolution expected to dramatically improve to the fundamental resolution, but also the coherent electron beam diffraction, the elemental analysis position system, the magnetic flux observation accuracy, etc. are brought about.

  Therefore, when a cathode manufactured in accordance with the invention of this application is incorporated with a photocathode-type electron power source and used as an electron beam source for an electron microscope such as a TEM, an accelerator, an X-ray generator, etc., the performance is dramatically improved. An electron beam source that can be improved greatly can be realized. And if the research of material development, physical properties research, basic physics, etc. advances by improving the performance of electron microscopes, electron beam accelerators, X-ray generators, etc., economic effects comparable to the invention of lasers in the optical field are expected. Is done.

  The invention of this application has the features as described above, and an embodiment thereof will be described below.

  A local coating apparatus for coating a cathode tip of a photocathode type electron beam source according to the invention of this application with a high quantum efficiency material includes a cathode tip and an emission source from which a constituent material of the high quantum efficiency material coating is emitted. A diaphragm having a hole for restricting a covering area to the cathode tip portion is disposed therebetween. With such a configuration, a high quantum efficiency substance can be locally coated at the center of the tip of the cathode, and a photocathode type electron beam source can be realized in which brightness and coherence are greatly improved simultaneously.

FIG. 8 is a conceptual diagram showing an embodiment of a local coating apparatus for coating a cathode tip of a photocathode type electron beam source according to the invention of this application with a high quantum efficiency material. In this embodiment, the cathode has the same structure as that shown in FIG. 7, and Cs ₃ Sb is coated as a high quantum efficiency material on the cathode tip by vapor deposition.

  The diaphragm used in the coating apparatus according to the invention of this application may be a fixed type or a movable type. The aperture can be made using a material such as platinum, tantalum, or carbon. The shape of the diaphragm can be an appropriate shape depending on the unit or holder in which the diaphragm is incorporated, but a disk-shaped one is usually used. The shape and size of the hole formed in the aperture can be appropriately set according to the use of the electron beam source. For example, when used for producing a cathode of an electron beam source of an electron microscope such as TEM, the diameter is usually 0.01. A circular hole of about 100 μm is used.

  As a method for making a small hole in the diaphragm, there are electrolytic polishing, electric discharge machining, focused ion beam drilling, and the like. Among them, the method that can make the smallest hole and control the shape of the hole is focused ion beam drilling shown in FIG. With the current technology, the diameter of the focused ion beam can be focused to 10 nm (nanometer) (= 100 angstroms) or less, so that a hole having a diameter of 10 nm or less can be drilled. Further, by controlling the voltage applied between the ion beam scanning electrodes by a computer, it is possible to make a hole having a free shape. For example, as shown in FIG. 10, an electron beam having a triangular cross section can be obtained by producing and using a diaphragm A having a triangular hole by focused ion beam drilling. Since the evaporating substance flies linearly in the vacuum, a local coating can be formed in the area of the same shape as the shape of the aperture hole in the cathode tip, which is proportional to the size of the aperture in the aperture. . Similarly, as shown in FIG. 10, if a diaphragm B having two adjacent minute round holes (for example, a hole diameter of 10 nm and a center-to-center distance of 15 nm) is prepared and used, An ultrafine electron beam (a beam with a diameter of 10 nm separated by 15 nm) can be obtained. This is not possible with other types of electron beam sources. If the two electron beams in the latter example are used, the present invention can be applied to basic physics research related to electron coherence.

  The diaphragm can be used as a unit or supported by a holder. For example, a disc-shaped aperture can be sandwiched between aperture holding plates and stored in an aperture storage cylinder, and fixed with a pressing member to form a unit.

  The diaphragm is preferably heated in order to prevent clogging due to the deposit when the cathode is coated with a high quantum efficiency material. In that case, current heating using a resistance wire such as tantalum or laser heating using an optical fiber can be used, and when both are used in combination, the heating effect is excellent. The heating temperature is set to a temperature higher than the melting temperature of the deposit. In order to effectively prevent clogging, a thermocouple for measuring the temperature of the throttle may be attached to the throttle to control heating.

As the high quantum efficiency material to be coated with the local coating apparatus of the invention of this application, any material that exhibits high quantum efficiency, such as Cs ₃ Sb, Na ₂ KSb, Rb ₃ Sb, and CsI, can be used. However, Cs ₃ Sb is particularly preferable.

As the cathode to be coated in the local coating apparatus of the invention of this application, any cathode can be used as long as it is a cathode used in a photocathode type electron beam source. The cooling type which the inventor has proposed in Patent Document 3 is cited. This type of cathode uses a combination of materials with high Peltier cooling efficiency, but because the Peltier effect works via the cathode tip made of a material with high thermal conductivity and electrical conductivity, the tip of the cathode tip is sharp. It is easy to make, and the strength is sufficient. A combination of thermoelectric semiconductors represented by a combination of some n-type semiconductors and p-type semiconductors (bismuth / tellurium-based, lead / tellurium-based, silicon / germanium-based, etc.) is used as the combination material having high Peltier cooling efficiency. In particular, it is preferable to use a combination of n-Bi ₂ Te ₃ and p-Bi ₂ Te ₃ . Moreover, copper, silver, or gold can be used suitably as a substance with high heat conductivity and electrical conductivity. When copper or silver is used, it is preferable to apply gold plating to the surface to eliminate the occurrence of thermal contact and electrical resistance due to surface oxidation. Further, the cathode is preferably used as a cathode unit having a cathode base, a cathode terminal, a Wehnelt cap and the like as shown in Patent Document 3.

As a high quantum efficiency substance emission source in the local coating apparatus of the invention of this application, when a vapor deposition method is used, an element constituting the high quantum efficiency substance can be accommodated in a vapor deposition boat. For example, when Cs ₃ Sb is used as a high quantum efficiency material, a Cs vapor deposition boat and Sb
The vapor deposition boat is placed on the vapor deposition boat mounting base. It is preferable to provide a plate for shielding radiant heat between the two evaporation boats. Further, it is preferable that the vapor deposition boat mounting base is movable by a known actuator, and the position of each vapor deposition boat is regulated by a stopper. When each evaporation boat is regulated, the line connecting the center of the centered aperture hole and the center of the cathode tip is the outlet hole of the evaporation boat containing the element to be evaporated (deposited material at the upper center of the evaporation boat) To be included in the exit area).

  It is preferable to provide an insulating plate for shielding the radiant heat on the emission source.

  In order to maintain the high quantum efficiency of the coating, it is also possible to provide a movable mask between the cathode tip and the emission source to prevent impurities other than the coating constituent materials from reaching the emission source. Is preferable. For example, when the vapor deposition method is used, impurities may evaporate from the vapor deposition boat and adhere to the tip of the cathode even when the temperature of the vapor deposition boat is low and the coating material does not evaporate. Then, such adhesion of impurities can be prevented.

  In the local coating apparatus of the invention of this application, an insulating cathode unit mounting base for incorporating a cathode and attaching a cathode unit mounted on a photocathode type electron beam source can be used. This insulating cathode unit mounting base has a mortar-shaped space in which a cathode unit incorporating a cathode is placed and accommodated in a direction in which the cathode tip faces the emission source, and a hollow opening is provided in the center of the bottom. The diaphragm unit for fixing and holding the diaphragm is fixed thereto.

  In this case, the position of the aperture hole fixed to the aperture unit can be adjusted within the recessed opening of the insulating cathode unit mounting base, and the center of the cathode tip and the aperture hole center by the stereomicroscope can be aligned. To be able to do. In order to perform axial alignment, the recess opening has a structure for adjusting the position in the horizontal plane direction. When the axial alignment is completed, the aperture unit can be fixed at that position by a fixing means such as a presser screw.

In the local coating apparatus of the invention of this application, when coating a high quantum efficiency material such as Cs ₃ Sb, it is preferable to heat the cathode tip in order to promote a chemical reaction. In order to maintain the quantum efficiency of the efficient substance as high as possible, it is preferable to immediately cool the cathode tip immediately after coating.

  When the cathode tip of the cathode bonded with a combination of substances having a high Peltier cooling effect is to be coated, the cathode tip is heated by energization using a resistance wire such as a tantalum wire, and the cathode tip is heated to the cathode. It is preferable to carry out by using together with heating by passing an electric current in the direction.

  The cathode tip is cooled by a combination of a water-cooled metal plate and a Peltier cooling thermo module for cooling the cathode tip, and by cooling the cathode by passing a current in the direction in which the cathode tip is cooled. It is preferable to carry out by using together.

  In the local coating apparatus of the invention of this application, the insulating cathode unit is used to maintain the quantum efficiency of the high quantum efficiency material coated on the cathode tip as high as possible by making the temperature of the cathode tip as low as possible after the coating is completed. It is necessary to prevent the temperature of peripheral parts such as the mounting base from becoming high. Therefore, it is preferable to place an insulating cathode unit mounting base on a water-cooled copper base and cool the copper base with antifreeze.

  There are some technical difficulties associated with local coating of a high quantum efficiency material on the tip of the cathode, and it is necessary to pay attention to the thickness of the coating film and to search for optimum deposition conditions. Therefore, it is desirable to check the coating state immediately after the high quantum efficiency substance is locally coated. Therefore, the local coating apparatus of the invention of this application is provided with a coating state inspection means (photoelectron detection means) for confirming the coating state immediately after the local coating in situ. FIG. 11 shows a conceptual diagram of the covering state inspection means.

  This coating state inspection means uses a Faraday cup, and the tip of an optical fiber for laser irradiation is inserted in the center of the bottom, the Faraday cup is connected to an ammeter, and the electrons emitted from the cathode tip The current by the beam can be detected, and the quality of the local coating can be inspected based on the result. Since the Faraday cup is movably installed in a space where the cathode tip and the emission source are limited, the Faraday cup has been modified as described above. When the electron beam emitted from the cathode tip directly travels straight, it collides with an optical fiber (electrical insulator). Therefore, deflection means such as an electrode plate or a magnetic field generating coil that deflects the traveling direction of the electron beam near the entrance of the Faraday cup. Is provided. In addition, when the aperture hole diameter is small, the number of electrons jumping into the Faraday cup is small. Therefore, for the purpose of increasing the number of electrons, it is preferable that the laser light irradiated to the cathode tip is made parallel light. Therefore, a convex lens for focusing the laser beam is provided near the tip of the optical fiber.

  The local coating by the local coating apparatus of the invention of this application can be performed by using a work cover in an inert gas with a glove as shown in Patent Documents 1 and 2, and in this way, the quantum by being exposed to oxygen. A decrease in efficiency can be prevented.

FIG. 12 shows a high quantum efficiency material (Cs ₃₎ locally coated on the cathode tip according to the invention of this application.
A conceptual diagram in which an electron beam is emitted by laser irradiation in Sb) is shown.

  Examples of the invention of this application will be described below, but the invention of this application is of course not limited to the following examples and the above-described embodiments, and various aspects are possible for details.

  FIG. 13 shows an embodiment of a device for locally coating a high quantum efficiency material on the cathode tip of a photocathode electron beam source according to the invention of this application.

  In FIG. 12, (10) is a cathode unit, (30) is an aperture unit, (40) is a vapor deposition unit, (50) is an insulating cathode unit mounting base, and (80) is a covering state inspection unit.

The cathode unit (10) used in this example uses a cooled cathode (11) similar to that shown in FIG. As shown in an enlarged view in FIG. 14, the cathode (11) is made of n-type Bi ₂ Te ₃ (12) and p-type Bi ₂ Te ₃ (13) having high Peltier cooling efficiency, each made of oxygen-free copper and Ni on the surface. The two cathode substrates (14) gold-plated after plating are joined using a solder having a high melting point of 221 ° C., and further heat conduction to each of n-type Bi ₂ Te ₃ (12) and p-type Bi ₂ Te ₃ (13). The cathode tip (15) made of copper, which is a material having a high rate and electrical conductivity, is joined using solder having a melting point of 221 ° C. Solder having a high melting point of 221 ° C. is used for bonding when the cathode tip (15) is locally coated with a high quantum efficiency material (Cs ₃ Sb in this example) at about 130 ° C. This is because heating is performed so that the solder does not melt. The tip surface of the cathode tip (15) is slightly concave as shown in FIG. 12, and is gold-plated before local coating with high quantum efficiency. The cathode substrate (14) is joined to the cathode terminal (17) supported by the insulated cathode substrate (16). A detachable cathode terminal contact (17 ′) is attached to the cathode terminal (17). Moreover, the tips of two pairs of thermocouples (18) and (19) for measuring the respective temperatures are screwed to the cathode base (14) and the cathode tip (15). A thermocouple terminal contact (20 ′) is attached to the thermocouple terminal (20) joined to the two thermocouples (18) and (19) with silver wax. A Wehnelt cap (22) is attached to the cathode unit (10).

  In this embodiment, in order to allow a high quantum efficiency material to be locally coated on the cathode tip (15), the diaphragm unit (30) is used, and the cathode unit (10) is mounted in advance. Install in the base (50). As shown in FIG. 15, the aperture unit (30) includes a pair of disc-shaped apertures (31) made of platinum and having fine holes (32) each having a diameter of 10 μm and a diameter of 2 mm and a thickness of 0.2 mm. Are held in a stainless steel diaphragm housing cylinder (34) and fixed with a diaphragm fixing screw (35). The fine hole (32) of the diaphragm (31) was formed by focused ion beam drilling shown in FIG. In FIG. 15, (33b) and (33d) are spacers (1) and (2), and (33c) and (33e) are spaces.

In this embodiment, an example in which the diaphragm (31) is housed in the diaphragm housing cylinder (34) of the diaphragm unit (30) is described. However, according to the invention of this application, in addition to this, the diaphragm housing cylinder. It is also possible to use a diaphragm holding plate and a spacer integrated with a micro screw without using the. This is to suppress the temperature rise of the insulating cathode unit (50) by setting the temperature only around the aperture (31) as high as 200 ° C. or higher (when coated with Cs ₃ Sb) as much as possible. In this case, an insulating spacer with small heat conduction is provided between the diaphragm holding plate and the insulating cathode unit (50), and the tantalum winding (61) and the thermocouple (65) for heating are directly attached to the diaphragm holding plate. Make contact. If it does in this way, since the temperature of the insulating cathode unit (50) during vapor deposition will become low, the cathode unit (10) after vapor deposition will not become high temperature, but there exists an advantage which can take out a cathode unit (10) quickly after vapor deposition. is there.

As shown in FIG. 13, the vapor deposition unit (40) includes an Sb vapor deposition boat (41) and a Cs vapor deposition boat (42). These vapor deposition boats (41) and (42) are vapor deposition boat mounts (43). ) Mounted and fixed on top. The Sb vapor deposition boat (41) contains Sb powder, and the Cs vapor deposition boat (42) contains Cs ₂ CrO ₄ , Al (reducing agent) and W (evaporation speed adjusting agent) powders. The vapor deposition boat mount (43) can be reciprocated as shown by arrows in FIG. 13 by an actuator (not shown). Further, the reciprocal movement is restricted by the stoppers (44) and (45), and when the vapor deposition boat mounting base (43) comes into contact with the stopper (44), the inside of the discharge port (42a) of the Cs vapor deposition boat (42). Further, the central axis of the hole (32) of the aperture (31) and the central axis of the cathode tip (15) (both are substantially coincident) are inserted. When the vapor deposition boat mounting base (43) is in contact with the stopper (45), the central axis of the discharge port (41a) of the Sb vapor deposition boat (41), the central axis of the hole (32) of the aperture (31), and the cathode The center axis of the tip (15) is made to coincide. The stoppers (44) and (45) are fixedly attached to a disc-like stopper mounting plate (46). Further, on the vapor deposition boat mounting base (43), between the Sb vapor deposition boat (41) and the Cs vapor deposition boat (42), the radiation heat from the mutual vapor deposition boats (41), (42) is cut off. A partition (47) for preventing heat radiation between the vapor deposition boats is provided. Further, a disk-shaped heat radiation blocking plate (48) for blocking radiant heat from these is also provided on the upper part of the vapor deposition boats (41), (42), and the vapor deposition boat (41) in the vapor deposition state or On the discharge port (41a) or (42b) of (42), a deposit discharge hole (49) through which the deposition beam passes is formed.

  The insulating cathode unit mounting base (50) is manufactured using, for example, McCall, which is easy to machine, and has a mounting space for mounting the cathode unit (10), and the bottom (51) has a mortar shape. A hollow opening (52) is formed at the center of the mortar-shaped bottom (51). A diaphragm unit (30) is mounted in the hollow opening (52) and is fixed by being pressed by a diaphragm unit pressing screw (53).

  Here, the position of the aperture unit (30) is adjusted to the hollow opening (52) of the insulating cathode unit mounting base (50) (the central axis of the hole (32) of the aperture (31) and the center of the cathode tip (15)). FIG. 16 shows a position adjusting mechanism for fixing by aligning the axes. A stereomicroscope (56) is used for the position adjustment mechanism (55). An insulative cathode unit mounting table (50) on which the cathode unit (10) is mounted can be placed on the spectroscopic table of the stereomicroscope (56) in a state where the top and bottom of FIG. The stereomicroscope (56) is connected to the CCD camera (58), and the CCD camera (58) is displayed on the screen of a CRT monitor (not shown). Reference numeral (59) denotes an intermediate lens barrel.

In this example, when the high quantum efficiency material (Cs ₃ Sb) is locally coated on the cathode tip (15), the hole (32) of the aperture (31) is attached to the constituent material of the released high quantum efficiency material. In order to prevent clogging, the aperture (31) is heated to about 200 ° C. This heating is performed by using a combination of current heating by the tantalum heating tantalum winding (63) and laser heating by irradiating laser light through the optical fiber (64) for introducing the laser for diaphragm heating. For this reason, in the insulating cathode unit mounting base (50), there are formed a winding passage for passing the tantalum heating tantalum winding (63) and an optical fiber passage for passing the squeezing heating laser introducing optical fiber (64). Has been. Further, in order to control the heating by measuring the temperature of the throttle (31), a thermocouple (65) for throttle temperature measurement is attached. Therefore, a thermocouple passage is formed in the insulating cathode unit mounting base (50) for passing the thermocouple (65) for restricting temperature measurement. In addition, a disk-shaped mounting copper plate (67) for attaching a tantalum wire for drawing heating (61) and a thermocouple for measuring the drawing temperature (65) is in contact with the drawing unit (30) in the hollow opening (52). Is provided. The tantalum wire (63) for heating the diaphragm and the thermocouple (65) for measuring the diaphragm temperature are attached to the mounting copper plate (67) by screwing into a screw hole formed in the insulating cathode unit mounting base (50). Is called.

  Since the insulating cathode unit mounting base (50) needs to maintain the quantum efficiency of the high quantum efficiency material after the local coating on the cathode tip (15) as high as possible, the peripheral parts of the insulating cathode unit mounting base (50) In order to prevent the temperature from becoming high, it is placed on a water-cooled copper base (68) and cooled with antifreeze.

In this example, the cathode tip (15) is heated to 130 ° C. during vapor deposition in order to promote chemical reaction and obtain a local coating of Cs ₃ Sb with higher quantum efficiency. Therefore, the cathode tip heating tantalum winding (69) is connected to the power source (PW) via the switch (SW2). Further, by using a combination of materials having a high Peltier cooling effect of the cathode (11), current flows in a direction (p-Bi ₂ Te ₃ → n-Bi ₂ Te ₃ ) in which heat is generated on the bonding surface. To do.

In this example, in order to maintain higher quantum efficiency of Cs ₃ Sb locally coated on the cathode tip (15), the cathode tip (15) is quickly cooled immediately after vapor deposition. Therefore, a commercially available Peltier cooling thermo module (70) is used. In this Peltier cooling thermo module (70), the side in contact with the tantalum wire quenching copper plate (71) and the quenching copper plate (72) such as the cathode tip is the cooling surface, and the side in contact with the water-cooled aluminum plate (73) is the heating surface. It is the composition which is arranged. Further, a current is passed through the cathode contact cooling copper wire (74) so that a current flows in the direction from n-type Bi ₂ Te ₃ to p-type Bi ₂ Te ₃ , thereby locally cooling the cathode tip (15). To do. Copper wire mounting screws (75a) and (75b) are provided on the tantalum wire rapid cooling copper plate (71), and copper wire mounting screws (76a) and (76b) are provided on the rapid cooling copper plate (72) such as the cathode tip. ) Is provided.

  Further, in this embodiment, a mask (77) for preventing impurities other than the covering constituent material from reaching the cathode tip (15) and the vapor deposition unit (40) from the vapor deposition unit (40) is moved. It is possible.

  Furthermore, in this embodiment, after confirming that the local coating has been successful, the conditions for the local coating and for the in-situ confirmation immediately after the vapor deposition for putting the cathode unit into the work of transferring to the electron beam generator such as TEM For searching, a covering state inspection unit (80) is provided. The covering state inspection unit (80) is configured using a Faraday cup (81) made of a metal cylinder. The structure of a normal Faraday cup is shown in FIG. If the entrance of electrons and ions is narrowed to some extent, the escape of secondary electrons can be prevented, so that the beam current can be measured accurately.

  Since the Faraday cup (81) of this embodiment must be movably disposed in a limited space between the cathode tip (15) and the vapor deposition unit (40), as shown in FIGS. Has been remodeled. That is, the optical fiber (83) is inserted so that the tip of the optical fiber (83) protrudes from the bottom of the Faraday cup (81), and the laser beam (84) is irradiated. The Faraday cup (81) is connected to an ammeter (85) so as to be able to detect a current due to an electron beam (86) emitted from the cathode tip (15) by laser irradiation. The Faraday cup (81) is attached to the insulating Faraday cup base (87).

When the electron beam (86) from the cathode tip (15) goes straight as it is, it collides with an optical fiber (electrical insulator) and charges up, so an insulating plate (88) is interposed near the entrance of the Faraday cup (81). An electrode plate (89) is provided. By this electrode plate (89), the traveling direction of the electron beam (86) is slightly bent as shown. In the figure, (90) is a conducting wire connected to the ammeter (85), and (91) is the core of the optical fiber (83).

  When the aperture (32) of the aperture (31) is somewhat large, the electron beam (86) from the cathode tip (15) can be detected by using a highly sensitive ammeter as the ammeter (85).

  Further, when the hole (32) of the diaphragm (31) is made smaller, the intensity of the laser beam (84) irradiated to the cathode tip (15) is reduced, so that the electrons jumping into the Faraday cup (81) are reduced. The number (current) decreases, and the current cannot be detected by the ammeter (85). Further, when the diameter of the inner core of the core (91) of the optical fiber (83) from which the laser beam (84) is emitted is small, the core portion becomes the central axis of the hole (32) of the aperture (31) and the cathode tip ( 15) It is necessary to adjust the position of the Faraday cup (81) with extremely high accuracy so that the laser beam (84) is applied to the cathode tip (15) so as to include the central axis of 15). There is. Therefore, in this case, as shown in FIG. 20, a lens mounting cylinder (92) is provided, and the tip of the optical fiber (83) is inserted therein, and a convex lens (93) is provided near the tip of the optical fiber (83). Thus, the laser beam (84) is made into a nearly parallel beam.

  When the acceleration voltage (kinetic energy) of the electron beam (86) is large, a magnetic field generating coil (94) is provided instead of the electrode plate (89) as shown in FIG. (86) is bent.

  Whether or not the deposited high quantum efficiency material has the original quantum efficiency can be determined from the current value of the emitted electron beam. This technique also provides inspection means in companies that sell cathode units when photocathode electron beam sources are put into practical use in the future.

  Next, the coating operation by the local coating apparatus of the embodiment having the above-described configuration will be described.

  First, a cathode unit (10) having the structure shown in FIGS. 13 and 14 is prepared. The diameter of the cathode tip (15) is 200 μm. Further, as shown in FIG. 15, a disc-shaped diaphragm (31) having a diameter of 2 mm and a thickness of 0.2 mm is produced by focusing ion beam drilling of a fine hole (32) made of platinum and having a diameter of 10 μm. The diaphragm (31) is held by a pair of copper diaphragm holding plates (33), accommodated in a stainless steel diaphragm storage cylinder (34), and fixed by a diaphragm fixing screw (35), and a diaphragm unit (30). And

  Next, as shown in FIG. 16, the cathode unit (10) is mounted on an insulating cathode unit mounting base (50) made by McCall, and the insulating cathode unit mounting base is placed with the hollow opening (52) facing upward. (50) is placed on the spectroscopic table of the stereomicroscope (55) and focused on the cathode tip (15). While observing the CRT monitor screen of the cathode tip (15) photographed by the CCD camera (58), the insulating cathode unit mounting base (so that the center of the cathode tip (15) is positioned at the center of the CRT monitor screen) 50) is moved slightly. Next, the diaphragm unit (30) is grasped with tweezers, put into the recessed opening (52) of the insulating cathode unit mounting base (50), and then the diaphragm (31) is focused. The aperture unit (30) is slightly moved in the horizontal plane so that the center of the hole (32) of the aperture (31) coincides with the center of the CRT monitor screen, and then the aperture unit (30) is used by using the aperture unit holding screw (53). ).

Next, as shown in FIG. 13, an insulating cathode unit mounting base (50) on which the cathode unit (10) is mounted and the aperture unit (30) is fixed is placed on the water-cooled copper base (68) of the apparatus main body, Connect the wiring and prepare for driving various members. Moreover, the inside of a vapor deposition apparatus is made into the high vacuum whose vacuum degree is higher than 1 * 10 <^-4> Pa.

Next, the switch (SW2) is turned on, and the diaphragm (31) is heated to 200 ° C. by the combined use of energization heating by the heating tantalum winding (61) and laser heating through the optical fiber (62) for introducing the diaphragm overheating laser. Heat to. On the other hand, the Sb deposition boat (42) is heated to 500 ° C. to deposit a required amount of Sb on the cathode tip (15). During this deposition, Sb is locally coated on the cathode tip (15) by the diaphragm (31) of the diaphragm unit (30). Thereafter, heating using a tantalum coil for heating the cathode tip portion (69) and a combination of materials having a high Peltier cooling effect for the cathode (11) (n-Bi ₂ Te ₃ (12) → p- The cathode tip (15) is heated to about 130 ° C. by the combined use of Bi ₂ Te ₃ (13) (current direction), and then the Cs deposition boat (41) is heated to 700 ° C. to deposit Cs. (Note that when the film is thickened, the deposition of Sb and the deposition of Cs are repeated). A film having the same shape as Sb is deposited at the same position and in the same size on the cathode tip (15) by the diaphragm (31), and the cathode tip (15) is heated. Reacts to form a local coating with high quantum efficiency Cs ₃ Sb. The diameter of the local coating was 10 μm.

When the vapor deposition is completed, the switch SW2 is turned off to stop the energization heating, and then the water-cooled aluminum plate (73) is rapidly cooled by flowing an antifreeze liquid that has been cooled in advance into the water-cooled aluminum plate (73) of FIG. At the same time, a current is passed through a commercially available Peltier cooling thermo module (70) so that the joining surface between the tantalum wire quenching copper plate (71) and the cathode tip cooling copper plate (72) is on the heat absorption side, and the tantalum wire quenching copper plate ( 71) and the cooling copper plate (72) such as the cathode tip are rapidly cooled, and the cathode tip heating tantalum winding (69), the cathode terminal contact (17 ') and the cathode terminal (17) are quenched by heat conduction. The tip (15) is quenched. At the same time, the switch (SW1) is turned on to cool the cathode (11) with a combination of materials having a high Peltier cooling effect (p-Bi ₂ Te ₃ (13) → n-Bi ₂ Te ₃ (12) (Current direction). As a result, the quantum efficiency of the locally coated Cs ₃ Sb is maintained as high as possible.

  The mask (77) is moved as necessary.

After the formation of the local coating, the coating state inspection unit (80) inspects the vapor deposition state of the locally coated Cs ₃ Sb. 18, 19, or 20, a laser beam (84) is applied to the cathode tip (15) from the optical fiber (83), and the emitted electron beam (86) is received by the Faraday cup (81). The current is detected by an ammeter (85), and the quality of vapor deposition is confirmed. If the vapor deposition is good, the cathode unit (10) can be taken out of the vapor deposition apparatus using the work cover in an inert gas with a glove shown in Patent Document 2 and loaded into an apparatus (TEM or the like) having an electron beam source. Like that. The state of the work is a procedure as shown in FIGS.

(A), (b), and (c) show the focusing of the electron beam for comparison of the luminance of the electron beam from thermionic emission electron beam source, field emission electron beam source, and photocathode electron beam source, respectively. It is a figure which shows a mode. (A), (b) is a figure which shows typically the outline | summary of the electrode for focusing of the electron beam in a thermoelectron emission type electron beam source and a field emission type electron beam source, respectively. (A) is an overall view of the cathode unit of the photocathode type electron beam source proposed in Patent Document 1, (b) is an enlarged view of the cathode of the cathode unit and the main part of the cathode, and (c) is an enlarged view of the cathode tip. is there. The vapor deposition apparatus proposed by the applicant of this application in Patent Document 1 and Patent Document 2 that can use a glove for a working cover in inert gas, and vapor deposition on the cathode tip of the cathode unit in the electron beam generator, cathode cathode unit It is a figure explaining clearly the flow of a series of work of taking out from a vapor deposition apparatus, attachment to the electron beam generator of a vapor deposition cathode unit, and operation | movement of an electron beam generator. It is a figure which expands and shows the cover for work in inert gas of FIG. It is a figure which shows a mode that the whole cathode unit is confined in an airtight container. (A) is a general view of the cathode unit used in the photocathode type electron beam source proposed in Patent Document 3, (b) and (c) are enlarged views of the main part of the cathode and cathode base of the cathode unit, and (d). FIG. 4 is an enlarged view of the cathode tip. It is a conceptual diagram which shows one Embodiment of the local coating | coated apparatus which coat | covers a high quantum efficiency substance on the cathode front-end | tip part of the photocathode type | mold electron beam source by invention of this application. It is explanatory drawing of focused ion beam drilling. It is explanatory drawing of formation of the aperture_diaphragm | restriction by focused ion beam drilling. It is a conceptual diagram of a covering state inspection unit. FIG. 3 is a conceptual diagram in which an electron beam is emitted by irradiating a high quantum efficiency material (Cs ₃ Sb) locally coated on the tip of a cathode according to the invention of this application. Indicates. It is a figure which shows one Example of the local coating | coated apparatus of the high quantum efficiency material to the cathode front-end | tip part of the photocathode type electron beam source by invention of this application. It is an enlarged view of the cathode unit of FIG. It is explanatory drawing of the aperture unit of FIG. It is explanatory drawing of the position adjustment mechanism of an aperture unit. It is a figure which shows the structure of a normal Faraday cup. It is explanatory drawing of a covering state test | inspection unit. It is explanatory drawing of the modified Faraday cup. It is explanatory drawing of another modified Faraday cup.

Explanation of symbols

10 Cathode unit 11 Cathode 12 n-type Bi ₂ Te ₃
13 p-type Bi ₂ Te ₃
14 Cathode base 15 Cathode tip 16 Insulated cathode base 17 Cathode terminal 17 'Cathode terminal contact 18, 19, 65 Thermocouple 20 Thermocouple terminal (two of the four)
20 'Thermocouple terminal contacts (two of the four)
22 Cathode Wehnelt 30 Diaphragm Unit 31 Diaphragm 32 Fine Hole 33 Diaphragm Holding Plate 33a Copper Diaphragm Holding Plate 33b Spacer (1)
33c Space 33d Spacer (2)
33e space 34 throttle housing cylinder 35 screw for fixing diaphragm 40 vapor deposition unit 41 vapor deposition boat for Sb 42 vapor deposition boat for Cs 43 vapor deposition boat mounting base 44, 45 stopper 46 stopper mounting plate 47 screen for preventing heat radiation between vapor deposition boats 48 heat radiation shielding plate 49 Vapor deposit discharge hole 50 Insulating cathode unit mounting base 51 Mortar-shaped bottom 52 Recessed opening 53 Aperture unit holding screw 55 Position adjustment mechanism 56 Stereo microscope 58 CCD camera 59 Intermediate lens barrel 63 Tantalum winding for aperture heating 64 For aperture heating Optical fiber 65 Thermocouple wire for temperature measurement of diaphragm 67 Copper plate for attachment of tantalum wire for heating and thermocouple 68 Water-cooled copper base 69 Tantalum winding for cathode tip heating 70 Peltier cooling thermo module 71 Copper plate for tantalum wire quenching 72 Cathode tip Copper plate for rapid cooling 7 3 Water-cooled aluminum plate 74 Copper wire for cathode contact cooling 75a Copper wire mounting screw (1 out of 8)
75b Copper wire mounting screw 76a Copper wire mounting screw 76b Copper wire mounting screw 77 Mask 80 Cover condition inspection unit 81 Faraday cup 83 Optical fiber 84 Laser light 85 Ammeter 86 Electron beam 87 Insulating Faraday cup base 88 Insulating plate 89 Electrode Plate 90 Conductor 91 Optical fiber core (core inside, clad outside)
92 Lens mounting cylinder 93 Convex lens 94 Magnetic field generating coil 100 Cathode unit 101 n-type Bi ₂ Te ₃
102 p-type Bi ₂ Te ₃
103 Cathode 104 Cathode Base 105 Cathode Terminal 106 Cathode Tip 107 Reinforcing Insulator 108 High Quantum Efficiency Material (Cs ₃ Sb)
110 Cathode unit 111 Cathode 112 Cathode base 113 N-type Bi ₂ Te ₃
114 p-type Bi ₂ Te ₃
115 Cathode tip 116 High quantum efficiency material (Cs ₃ Sb)
151 Cover for working in inert gas 152 Valve 153 Valve 154 Flange lifting handle 155 Cathode unit sealed container inlet / outlet 156 Lid 157 Globe 158 Inner pocket 159 Vacuum flange 160 O-ring 161 Bolt 162 Nut 163 O-ring 164 O-ring tightening ring 165 Cover Seat 201 Working cover in inert gas 202 Valve 203 Valve 204 Flange roll-up / down handle 205 Cathode unit sealed container inlet / outlet 206 Lid 207 Globe 208 Inner pocket 209 Vacuum flange 300 Cathode unit 301 Sealed container 302 O-ring 303 Butterfly screw 304 Ultra high purity Inert gas

Claims (16)

The tip of the cathode with a sharp tip in a device that coats the surface of the cathode tip of the photocathode type electron beam source of the laser irradiation method from the side where electrons are emitted from the coated high quantum efficiency material Between the surface of the cathode and the emission source from which the constituent material of the high quantum efficiency material coating is emitted, a stop having a microhole for limiting the coating area on the cathode tip is not adhered to the cathode tip. A plurality of constituent materials are attached at the same position to form a high quantum efficiency material , a negative voltage can be applied to the cathode tip with respect to the ground, and from the center of the bottom of the Faraday cup and the Faraday cup, It consists of an optical fiber for irradiating laser light to cause external photoelectric effect on the cathode tip coated with high quantum efficiency material, and after the coating on the cathode tip is finished, the laser light is applied to the cathode tip A movable covering state inspection means for measuring the covering state based on the result of measuring an electron beam emitted from the tip of the cathode by the external photoelectric effect as a current value, and entering the Faraday cup photocathode type laser irradiation method from a side of electrons from the high quantum efficiency material coated, characterized in Rukoto provided deflection means close to deflect the traveling direction of the electron beam emitted from the cathode tip is released A device for locally coating a high quantum efficiency material on the cathode tip of an electron beam source.
The local coating apparatus according to claim 1, wherein the coating apparatus is a vacuum deposition apparatus. The local coating apparatus according to claim 1, further comprising a diaphragm heating unit that heats the diaphragm. 4. The local coating apparatus according to claim 3, wherein the aperture heating means is a combination of an energization heating means and a laser heating means via an optical fiber. A geometry that has a plurality of emission sources, these emission sources are mounted on a mounting member, and the axis connecting the center of the cathode tip and the center of the aperture of the aperture is the geometry from which the coating material is released from the emission source The local covering apparatus according to claim 1, wherein the mounting member is movable so as to be within a target range. 6. The local coating apparatus according to claim 5, wherein a plate for shielding radiant heat is provided between a plurality of emission sources on the mounting member. The local plate according to any one of claims 1 to 6, wherein an insulating plate for shielding radiation heat is provided on the emission source having an opening through which the coating material is emitted. Coating equipment. Insulating cathode unit mounting base for mounting a cathode unit that incorporates a cathode and mounted on a photocathode-type electron beam source, and an aperture unit for fixing and holding the aperture is fixed to the recessed opening of the insulating cathode unit mounting base The local coating apparatus according to any one of claims 1 to 7, wherein the local coating apparatus is configured as described above. The position of the aperture hole fixed to the aperture unit can be adjusted within the recessed opening of the insulating cathode unit mounting base, so that the cathode tip and the aperture center of the aperture can be aligned with a stereomicroscope. The local coating apparatus according to claim 8, wherein: 2. The diaphragm according to claim 1, wherein the diaphragm has a sufficient mechanical strength, and one or more fine holes are formed by using a focused ion beam, electropolishing or electric discharge machining. The local coating apparatus according to any one of 9. A diaphragm in which a recess of the required size is formed in the central part of the diaphragm, and one or two or more fine holes of any shape are formed by computer control of a scanning electrode plate with a focused ion beam The local coating apparatus according to claim 1, wherein: The cathode tip of the cathode to which a substance with a high Peltier cooling effect is bonded is to be covered, and a power source for supplying current to the cathode is provided, and heating and cooling of the cathode tip can be selected by selecting the direction of current flow. The local coating apparatus according to any one of claims 1 to 11, wherein There is an electric heating means for heating the cathode tip, and the cathode tip is heated by a combination of heating by the current heating means and heating by passing a current in the direction in which the cathode tip is heated to the cathode. The local coating apparatus according to claim 12, which is configured as described above. It has a combination of a water-cooled metal plate and a Peltier cooling thermo module for cooling the cathode tip, and a combination of cooling by this combination and cooling by flowing current in the direction in which the cathode tip is cooled to the cathode The local coating apparatus according to claim 12, wherein the cathode tip is cooled. 15. A movable mask for preventing impurities other than the coating material from reaching from the emission tip to the cathode tip and the emission source. The topical coating device described. 16. The local coating apparatus according to claim 1, wherein a laser beam focusing lens for causing an external photoelectric effect is provided in the vicinity of the tip of an optical fiber attached to the Faraday cup.

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