JP6809809B2 - Insulated structure, charged particle gun and charged particle beam application device - Google Patents

Description

The present invention relates to an insulating structure, a charged particle gun and a charged particle beam application device. More specifically, it relates to an insulating structure, a charged particle gun and a charged particle beam application device used by being connected to a high voltage power source.

Examples of the charged particle beam application device include a scanning electron microscope (hereinafter abbreviated as "SEM"), an EPMA (Electron Probe Micro Analyzer), an electron beam welder, a focused ion beam, a transmission electron microscope, and an open type. There are X-ray devices and electron beam drawing devices. A charged particle gun such as an electron gun that emits an electron beam is used in these charged particle beam application devices. For example, a thermionic emission type electron gun emits an electron beam when an electron source placed in a vacuum environment is heated. The electron source is generally supported by an insulating insulator placed between the vacuum environment and the atmospheric pressure environment. A high voltage is applied to the electron source.

The electron gun is required to have high withstand voltage performance so that a high voltage can be stably applied for a long time. In order to satisfy such withstand voltage performance, it is important that the potential gradient around the insulator for insulation is gentle. In particular, if the potential gradient between the periphery of the Wenert electrode and the periphery of the insulator is steep, electric discharge is likely to occur.

In response to such a problem, in Patent Document 1 below, in a field emission electron gun, a metallized groove is provided in the extraction electrode mounting portion of the porcelain, and the potential of the groove portion is set to the same potential as the extraction electrode. It is disclosed to make the gradient gentle.

JP-A-2002-313269

However, in the structure described in Patent Document 1, the metallized groove portion and the extraction electrode have the same potential. Since there is an electric field from the extraction electrode toward the high-voltage insulation insulator at the side portion of the electric field extraction electrode and the peripheral portion of the high-voltage insulation insulator, electrons are likely to be emitted toward the high-voltage insulation insulator. Therefore, when minute electron emission occurs and secondary electron emission occurs from the insulator, the high-voltage insulating insulator is positively charged. When the high-voltage insulating insulator is positively charged, the electric field between the extraction electrode and the high-voltage insulating insulator is strengthened, the electron emission is further increased, gas emission and ionization are generated, and creeping discharge is likely to occur.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an insulating structure having high withstand voltage performance, a charged particle gun, and a charged particle beam application device.

According to an aspect of the present invention to achieve the above object, the insulating structure used in connection with the high voltage power supply includes a first electrode, a second electrode having a higher potential than the first electrode, and a first electrode. The solid dielectric material in contact with the electrode and the second electrode, and the third electrode are provided, and the first electrode, the second electrode, and the third electrode are connected to a high-voltage power source and are solid. On the surface of the dielectric, the portion located between the first electrode and the second electrode is the interface in contact with either vacuum, gas, or liquid, and the third electrode is from the interface. , It is arranged at a position away from the solid dielectric side, and the potential of the third electrode is lower than the potential of the first electrode.

According to another aspect of the present invention, the insulating structure used connected to the high voltage power supply includes a first electrode, a second electrode having a higher potential than the first electrode, a first electrode and a second electrode. A solid dielectric in contact with the electrode and a third electrode are provided, and the first electrode, the second electrode, and the third electrode are connected to a high-voltage power source and are on the surface of the solid dielectric. Of these, the portion located between the first electrode and the second electrode is the boundary surface in contact with any of vacuum, gas, or liquid, and the third electrode is separated from the boundary surface toward the solid dielectric side. The potential of the third electrode is higher than the potential of the second electrode.

According to yet another aspect of the present invention, the insulating structure used in connection with a high voltage power source is a first electrode, a second electrode having a higher potential than the first electrode, a first electrode and a first electrode. A solid dielectric in contact with the second electrode and a third electrode are provided, and the portion of the surface of the solid dielectric located between the first electrode and the second electrode is a vacuum or gas. , Or the interface in contact with the liquid, the third electrode is arranged at a position away from the interface on the solid dielectric side, and the potential of the third electrode is the potential of the first electrode. It has become lower than a first electrode, a second electrode, a third electrode, each of the solid dielectric, has a substantially axisymmetric shape with respect to the same central axis.
According to yet another aspect of the present invention, the insulating structure used in connection with a high voltage power source is a first electrode, a second electrode having a higher potential than the first electrode, a first electrode and a first electrode. A solid dielectric in contact with the second electrode and a third electrode are provided, and the portion of the surface of the solid dielectric located between the first electrode and the second electrode is a vacuum or gas. , Or the interface in contact with the liquid, the third electrode is located at a position away from the interface on the solid dielectric side, and the potential of the third electrode is higher than the potential of the second electrode. The first electrode, the second electrode, the third electrode, and the solid dielectric each have a substantially axially symmetric shape with respect to the same central axis.

Preferably, the first electrode or the second electrode is the ground potential.

According to yet another aspect of the present invention, the insulating structure used in connection with a high voltage power supply includes a first electrode, a second electrode having a higher potential than the first electrode, a first electrode and a first electrode. A solid dielectric in contact with the second electrode and a third electrode are provided, and the portion of the surface of the solid dielectric located between the first electrode and the second electrode is a vacuum or gas. , Or the interface in contact with the liquid, the third electrode is arranged at a position away from the interface on the solid dielectric side, and the potential of the third electrode is the potential of the first electrode. The solid dielectric has a groove formed to divide the interface from the first electrode to the second electrode.
According to yet another aspect of the present invention, the insulating structure used in connection with the high voltage power supply includes a first electrode, a second electrode having a higher potential than the first electrode, a first electrode and a first electrode. A solid dielectric in contact with the second electrode and a third electrode are provided, and the portion of the surface of the solid dielectric that is located between the first electrode and the second electrode is a vacuum or gas. , Or a boundary surface in contact with either liquid, the third electrode is arranged at a position away from the boundary surface on the solid dielectric side, and the potential of the third electrode is higher than the potential of the second electrode. The solid dielectric also has a groove formed to divide the interface from the first electrode to the second electrode.

According to yet another aspect of the present invention, a charged particle gun that emits charged particles having the insulating structure described above, the solid dielectric has a support that supports the charged particle source and is a first electrode. Is a guard ring arranged so as to be in contact with the support portion, and a second electrode is a vacuum chamber wall arranged so as to be in contact with the solid dielectric material and surround the circumference of the charged particle source. The electrodes of are arranged on the opposite side of the guard ring with respect to the solid dielectric and are ring electrodes having a ring shape, and the charged particle guns are each conductive and have a plurality of penetrating solid dielectrics. It has a penetrating member, the charged particle source is connected to a pair of penetrating members among the plurality of penetrating members, and the guard ring is connected to any of the plurality of penetrating members.

Preferably, the vacuum chamber wall is connected to the ground potential.

Preferably, one of the pair of penetrating members to which the charged particle source is connected and the guard ring are electrically connected.

Preferably, the guard ring is connected to a potential higher than the potential of the charged particle source.

Preferably, the guard ring is electrically connected to a first anode portion that draws charged particle source electrons from the charged particle source.

Preferably, the charged particle gun is connected to one of a plurality of penetrating members, further comprising a limiting electrode that limits the amount of charged particles emitted from the charged particle gun, and a penetrating member connected to the limiting electrode. Is electrically connected to the third electrode.

Preferably, the outermost peripheral portion of the ring electrode is located outside the peripheral edge portion of the guard ring.

Preferably, the solid dielectric is an insulating member and the support is formed so as to project in the exit direction of the charged particles.

Preferably, the guard ring has a concave shape that covers the protruding end of the support, and the upper end of the guard ring has a round chamfer shape with an arcuate portion in cross section.

Preferably, the support has a recess that opens in a direction opposite to the exit direction of the charged particles, and the ring electrode is located inside the recess.

Preferably, the potential of each of the plurality of penetrating members is given by a voltage divider circuit using two or more resistors.

According to still another aspect of the present invention, the charged particle beam application device comprises the charged particle gun described above, an objective lens that focuses the charged particle beam emitted from the charged particle gun on a sample, and an incident of the charged particle beam. It is equipped with a detector that detects the reflected electrons emitted from the sample.

According to the present invention, it is possible to provide an insulating structure having high withstand voltage performance, a charged particle gun, and a charged particle beam application device.

It is a figure which shows the schematic structure of the SEM which concerns on 1st Embodiment of this invention. It is a figure which shows schematic structure of the electron gun. It is a figure which shows typically the distribution of the equipotential lines around the insulator of an electron gun. It is a figure which shows typically the schematic structure of the electron gun which concerns on one modification of 1st Embodiment. It is a figure which shows typically the schematic structure of the electron gun which concerns on still another modification of 1st Embodiment. It is a figure which shows schematic structure of the electron gun of the SEM, the transmission electron microscope, and the open type X-ray apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the 1st example of an insulation structure. It is a side view explaining the 1st example of an insulation structure. It is a figure explaining the 2nd example of an insulation structure. It is a figure explaining the 3rd example of an insulation structure.

Next, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the drawings below are schematic and the dimensions and aspect ratios may differ from the actual ones.

Further, the embodiments of the present invention shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material and shape of the component parts. , Structure, arrangement, etc. are not specified as follows. The technical idea of the present invention can be modified in various ways within the technical scope described in the claims.

[First Embodiment]
FIG. 1 is a diagram showing a schematic configuration of an SEM according to the first embodiment of the present invention.

[Outline configuration of SEM]
As shown in FIG. 1, the SEM (an example of a charged particle beam application device) 100 focuses an electron gun 50 that emits and accelerates a primary electron beam (charged particle beam) 12 and an accelerated primary electron beam 12. The condenser lens 15, the objective lens aperture 16 excluding unnecessary parts of the primary electron beam 12, the two-stage deflection coil 17 that scans the primary electron beam 12 two-dimensionally on the sample 23, and the primary electron beam 12 as a sample. An electron beam device including an objective lens 18 focused on 23, and a secondary electron detector 19 and a detector 20 for detecting signal electrons 21 (secondary electrons 21a, reflected electrons 21b) emitted from the sample 23. is there.

The SEM 100 includes an objective lens power supply 41 that changes the intensity of the objective lens 18 and a control device 45 that controls the objective lens power supply 41 as a control unit for the electromagnetic lens.

The control device 45 can control the intensity of the objective lens 18. Further, although not shown in the figure, each power source can be adjusted by being connected to the control device 45.

The electron gun 50 has an electron source (charged particle source) 11 and an acceleration power source 14 for accelerating the primary electron beam (charged particle beam) 12 emitted from the electron source 11.

As the electron source 11, a thermionic emission type (thermoelectron source type) and a field emission type (Schottky type or cold cathode type) can be used. In the first embodiment, a crystal electron source such as a thermoelectron emitting type LaB6 or a tungsten filament is used as the electron source 11. The acceleration power supply 14 applies, for example, an acceleration voltage of −0.5 kV to −30 kV between the electron source 11 and the anode plate 14d, which is used as the ground potential. The Wenert electrode 13 is given a potential more negative than the potential of the electron source 11 due to the bias voltage. As a result, the amount of the primary electron beam 12 generated from the electron source 11 is controlled. Then, a crossover diameter, which is the first minimum diameter of the primary electron beam 12, is formed immediately in front of the electron source 11 (the output direction of the primary electron beam 12; hereinafter, may be referred to as downward). This minimum diameter is called the size So of the electron source.

The accelerated primary electron beam 12 is focused by the condenser lens 15, and the size So of the electron source is reduced. The reduction ratio and the current (probe current) applied to the sample 23 are adjusted by the condenser lens 15. Then, the objective lens diaphragm 16 removes unnecessary orbital electrons. The opening angle α of the beam incident on the sample 23 and the probe current are adjusted by the hole diameter of the objective lens diaphragm 16.

The primary electron beam 12 that has passed through the objective lens diaphragm 16 passes through the two-stage deflection coil 17. The SEM100 scans the sample 23 two-dimensionally by adjusting the two-stage deflection coil 17. The two-stage deflection coil 17 includes an upper deflection coil 17a on the electron source side and a lower deflection coil 17b on the sample side.

The two-stage deflection coil 17 is driven by an upper-stage deflection power supply 43 that changes the strength of the upper-stage deflection coil 17a and a lower-stage deflection power supply 44 that changes the strength of the lower-stage deflection coil 17b. The upper deflection power supply 43 and the lower deflection power supply 44 are controlled by the control device 45.

The primary electron beam 12 that has passed through the two-stage change coil 17 passes through the objective lens 18. The objective lens 18 adjusts the focus of the primary electron beam 12 so that it is on the sample 23. The primary electron beam 12 is emitted from a hole provided in the lower part of the objective lens 18.

The primary electron beam 12 scans on the sample 23 with the energy accelerated by the acceleration power supply 14. The secondary electrons 21a emitted from the sample 23 are deflected by the drawn electric field from the secondary electron detector 19 and captured by the secondary electron detector 19. That is, the secondary electron detector 19 is arranged so that the electric field generated from the secondary electron detector 19 attracts the secondary electrons 21a emitted from the sample 23 by the charged particles.

[Configuration of electron gun 50]
FIG. 2 is a diagram schematically showing a schematic configuration of the electron gun 50.

As shown in FIG. 2, the electron gun 50 is roughly described on the side of the electron gun chamber (an example of the first region) 10a and the side of the outer atmospheric pressure (an example of the second region) of the electron gun chamber 10a. It is divided into both parts. The electron gun chamber 10a is surrounded by an insulator (an example of an insulating member and a solid dielectric) 51 and a vacuum chamber wall (an example of a second electrode) 10 via an O-ring 50a, and a vacuum environment is maintained. .. An electron source 11, a Wenert electrode 13, and an anode plate 14d are arranged in the electron gun chamber 10a.

The insulator 51 has a concave shape that is roughly recessed upward. In other words, the insulator 51 has a bowl shape in which a peripheral wall portion 51b protruding downward is provided on the peripheral edge portion of the upper plate portion 51a which is a substantially horizontal plate shape. At the center of the upper plate portion 51a of the insulator 51, a support portion 51c that protrudes downward is formed so that the amount of protrusion is smaller than that of the peripheral wall portion 51b. The material of the insulator 51 is a solid dielectric, for example, ceramics, glass, resin, and a mixture thereof.

Both ends of the filament 11a of the electron source 11 are attached to two high-pressure introduction connection pins on the filament side (hereinafter, may be referred to as filament connection pins; an example of a penetrating member (first penetrating member)) 52a. There is. The filament connecting pin 52a has conductivity and is arranged so as to penetrate the support portion 51c of the insulator 51 from the electron gun chamber 10a side to the atmospheric pressure side. The filament connecting pin 52a is supported by the insulator 51. That is, the insulator 51 holds the electron source 11 on the electron gun chamber 10a side. The filament 11a is connected to the high-voltage introduction cable 14a connected to the acceleration power supply 14 on the atmospheric pressure side via the filament connection pin 52a. A voltage is applied to the filament 11a by the acceleration power supply 14, and thermions are emitted from the tip of the filament 11a.

In the insulator 51, a high-pressure introduction connection pin on the Wehnelt side (hereinafter, referred to as a Wehnelt connection pin) electrically connected to a Wehnelt electrode (an example of a limiting electrode that limits the amount of charged particles) 13; a penetrating member (the first). Example of 2) through member) 52b is attached. The Wenert connection pin 52b has conductivity and is arranged so as to penetrate the support portion 51c of the insulator 51 from the electron gun chamber 10a side to the atmospheric pressure side. The Wenelt electrode 13 is connected to the high-voltage introduction cable 14a connected to the acceleration power supply 14 on the atmospheric pressure side via the Wenelt connection pin 52b. The acceleration power supply 14 applies a bias voltage to the Wenert electrode 13. The Wenert electrode 13 is an electrode that is biased to a negative voltage with respect to the electron source 11.

The portion of the electron gun 50 on the atmospheric pressure side above the chamber wall 10 is covered with the electron gun cover 58 so that, for example, the high-voltage introduction cable 14a penetrates to the outside. The inside of the electron gun cover 58 is filled with silicone rubber 59, resin, or the like. As a result, creeping discharge does not occur from the high-voltage portion.

In the first embodiment, a guard ring (an example of the first electrode) 54 is arranged below the support portion 51c of the insulator 51 (a portion on the electron gun chamber 10a side) and above the filament 11a. ing. The guard ring 54 is arranged at a position closer to the support portion 51c than the electron source 11. The guard ring 54 has, for example, a substantially horizontal disk shape. The guard ring 54 is arranged so that the axis at the center thereof passes through the portion where the primary electron beam 12 is emitted. The guard ring 54 is arranged so that the peripheral edge portion projects laterally from the support portion 51c.

The guard ring 54 is electrically connected to one of the two filament connecting pins 52a, for example, via a conducting wire or the like.

The peripheral wall portion 51b of the insulator 51 is in contact with the chamber wall 10. The creepage discharge path R is a path from the guard ring 54 to the chamber wall 10, which is the ground potential, through the boundary surface of the insulator 51 in contact with the vacuum. The chamber wall 10 has a high potential with respect to the guard ring 54.

Further, in the first embodiment, a ring electrode (an example of a third electrode) 56 is arranged on the upper surface (surface on the atmospheric pressure side) of the upper plate portion 51a of the insulator 51. The ring electrode 56 is a conductive material, for example, a metal member that is formed in an annular shape in advance. The ring electrode 56 is arranged on the upper surface of the insulator 51 so as to bulge upward in an annular shape from the upper surface of the insulator 51. The upper portion of the ring electrode 56 is formed to be rounded so that the cross section has a semicircular shape, for example. The ring electrode 56 is arranged so that the filament connection pin 52a and the Wenert connection pin 52b are located inside the annular portion thereof. The shape of the ring electrode 56 is not limited to an annular shape, and may be a ring shape such as a polygon.

The ring electrode 56 is made of a metal mainly containing, for example, copper or aluminum, but is not limited to this, and may be, for example, a graphite electrode. When a metal having relatively excellent thermal conductivity such as a copper alloy or an aluminum alloy is used as the ring electrode 56, the heat dissipation effect of the electron gun 50 can be obtained.

The ring electrode 56 may be fixed to the upper surface of the insulator 51 using, for example, an adhesive. The ring electrode 56 may be fixed to the surface of the insulator 51 on the atmospheric pressure side by using a fixing member or the like that engages with the Wenert connection pin 52b or the like.

The ring electrode 56 is arranged so that the central axis passing vertically through the center of the ring of the ring electrode 56 passes through the portion where the primary electron beam 12 is emitted. That is, the annular portion of the ring electrode 56, the guard ring 54, and the electron source 11 are arranged substantially coaxially. The outermost peripheral portion of the ring electrode 56 is located lateral to the peripheral edge portion of the guard ring 54. In other words, the distance from the central axis to the outermost peripheral portion of the ring electrode 56 is slightly larger than the distance from the central axis to the peripheral edge portion of the guard ring 54. The distance from the central axis to the outermost peripheral portion of the ring electrode 56 and the distance from the central axis to the peripheral edge portion of the guard ring 54 may be substantially equal. For example, the position of the outermost edge of the guard ring 54 on each of the electron gun chamber 10a side (lower in FIG. 2) and the atmospheric pressure side (upper in FIG. 2) of the insulator 51 is the electron gun chamber 10a side or When viewed from one side of the atmospheric pressure side, they may be substantially overlapped. That is, the outer diameter of the ring electrode 56 can be set according to the position of the outermost peripheral portion of the guard ring 54.

The ring electrode 56 is electrically connected to the Wenert connection pin 52b, for example, via a conducting wire or the like. As a result, the Wenert electrode 13 and the ring electrode 56 have the same potential. The ring electrode 56 may be fixed by a metal fixing member or the like that engages with the Wehnelt connection pin 52b, whereby the ring electrode 56 may be electrically connected to the Wehnelt connection pin 52b. Further, the ring electrode 56 and the Wenelt connection pin 52b may be fixed in a state where the Weinert connection pin 52b is in contact with a part of the ring electrode 56 to be conductive.

Here, the bias voltage (Wenert potential) applied to the Wehnelt electrode 13 is lower than the voltage (filament potential) applied to the filament 11a by the acceleration power supply 14. Therefore, the potential of the ring electrode 56 is lower than the potential of the guard ring 54. For example, the filament potential is −30 kV (kilovolt) and the Wenert potential is −31 kV. In this case, the potential of the guard ring 54 becomes minus 30 kV, and the potential of the ring electrode 56 becomes minus 31 kV.

FIG. 3 is a diagram schematically showing the distribution of equipotential lines around the insulator 51 of the electron gun 50.

In FIG. 3, an example of equipotential lines is shown by an alternate long and short dash line. As shown in FIG. 3, in the first embodiment, a guard ring 54 is arranged on the electron gun chamber 10a side of the insulator 51 so as to project outward from the support portion 51c, and the insulator 51 is placed. The ring electrode 56 is arranged on the atmospheric pressure side above the sandwich. The potential of the ring electrode 56 is lower than the potential of the guard ring 54. Therefore, the equipotential lines between the guard ring 54 and the ring electrode 56 are close to parallel to the side surface of the protruding support portion 51c. That is, the side surface of the support portion 51c becomes close to the same potential, and the force along the creeping surface does not act on the electrons. Further, in the path from the side surface of the support portion 51c to the peripheral wall portion 51b, the potential of the ring electrode 56 is lower than that of the guard ring 54, so that the force acting on the electrons toward the peripheral wall portion 51 becomes weak. Alternatively, since the electrons receive a force in the opposite direction, the movement of the electrons to the peripheral wall portion 51 is hindered. Therefore, when a high voltage is applied to the electron source 11, even if an electron emission phenomenon that may cause creepage discharge occurs in the past, electron emission is less likely to be chained on the surface portion of the support portion 51c, and creepage discharge occurs. Is prevented. Therefore, the withstand voltage performance of the electron gun 50 can be improved. Since the structure is simple with the guard ring 54 and the ring electrode 56, the manufacturing cost of the electron gun 50 and the SEM100 using the electron gun 50 can be kept low.

Further, if the potential gradient around the insulator 51 is steep, the electron emission phenomenon, gas desorption, ionization, etc. become active, and discharge is likely to occur. In order to reduce the possibility of electric discharge, it is conceivable to separate electrodes having different potentials. At this time, considering the influence on the potential gradient, it is conceivable to widen the distance between the electrodes or to arrange the electrodes at ideal positions. However, if the electrodes are arranged in this way, there is a problem that the electron gun becomes large. On the other hand, in the first embodiment, since the annular ring electrode is arranged on the upper surface of the insulator 51, the potential gradient around the guard ring 54 and the support portion 51c becomes relatively gentle. Therefore, it is possible to achieve both the miniaturization of the electron gun 50 and the improvement of the withstand voltage performance.

As the ring electrode 56, an electric field in the above-mentioned direction is generated depending on the position of the guard ring 54 in the electron gun 50, the shape of the insulator 51, and the like, and the bias of the electric field strength is small (equal potential lines). It is advisable to appropriately use a shape and a size that causes (small local distortion). As a result, the possibility of electric discharge can be further reduced, and the electron gun can be stably driven at a high voltage.

Further, instead of the insulator 51 having the protruding support portion 51c as described above, an insulator having a concave shape recessed upward may be used, in which the lower surface side of the support portion is formed in a flat shape. In this case, it is preferable to make the outer diameter of the ring electrode 56 larger than the outer diameter of the guard ring 54. Since the potential of the ring electrode 56 is lower than that of the guard ring 54, the force for directing electrons toward the peripheral wall portion is weakened. Alternatively, since the electrons receive a force in the opposite direction, the movement of the electrons to the peripheral wall portion is hindered. In this case as well, the possibility of electric discharge can be reduced.

The ring electrode 56 can be easily attached to the insulator 51 when assembling the electron gun 50. Therefore, the electron gun 50 can be easily assembled without requiring a complicated work process such as providing a metallized electrode, and the manufacturing cost of the electron gun 50 can be reduced. The ring electrode 56 may be provided by performing a metallizing treatment on the upper surface of the insulator 51, instead of attaching a ring electrode 56 molded in an annular shape to the insulator 51 in advance.

The guard ring 54 is connected to the filament connecting pin 52a to obtain a filament potential. Then, the ring electrode 56 is connected to the Wenert connection pin to obtain the Wenert potential. Therefore, in order to make the potential of the ring electrode 56 lower than the potential of the guard ring 54, it is not necessary to prepare a dedicated power supply or an electric wire such as a high voltage introduction cable 14a, and the configuration of the electron gun 50 can be simplified. it can.

[Modified example of the first embodiment]
FIG. 4 is a diagram schematically showing a schematic configuration of an electron gun 250 according to a modification of the first embodiment.

As shown in FIG. 4, the electron gun 250 differs from the electron gun 50 in the following points. A recess 251d is formed inside the support portion 51c of the insulator (an example of an insulating member and a solid dielectric) 251. A guard ring 254 having a shape different from that of the guard ring 54 in the vicinity of the peripheral edge is provided. A ring electrode 256 having a different shape inside the ring from the ring electrode 56 is provided. In addition, the electron gun 250 is configured in the same manner as the electron gun 50, except for the parts not particularly described below.

A protruding portion 254a having a shape protruding upward is provided in the vicinity of the peripheral edge portion of the guard ring 254. The protrusion 254a is formed so as to surround the outer side of the lower portion of the support portion 51c. The upper end of the protrusion 254a is formed to be rounded so that the cross section has a semicircular shape, for example.

The recess 251d is formed so as to be recessed downward so as to open toward the atmospheric pressure side (upward). The vertical position of the bottom of the recess 251d is substantially the same as or below the top of the protrusion 254a. The inner surface of the recess 251d is located laterally to the filament connecting pin 52a. Inside the recess 251d, the filament connecting pin 52a is exposed to the atmospheric pressure side.

The ring electrode 256 has an annular portion 256a and a tubular portion 256d. The annular portion 256a is formed in the same manner as the ring electrode 56. The tubular portion 256d is connected to the inner lower portion of the annular portion 256a. The tubular portion 256d has a shape along the upper surface of the upper plate portion 51a of the insulator 251 and the inner side surface of the recess 251d. The lower end of the tubular portion 256d is located near the bottom of the concave portion 251d. The ring electrode 256 is fixed to the insulator 251 in the same manner as the ring electrode 56 in a state of being fitted in the recess 251d.

The ring electrode 256 may be an annular portion 256a and a tubular portion 256d molded at one time using a mold (cut product, cast product, press-molded product, etc.), or the annular portion 256a and the tubular portion 256d. And may be separately molded and then joined to each other. Either or both of the annular portion 256a and the tubular portion 256d may be coated with a metallized electrode or a conductive material. The annular portion 256a and the tubular portion 256d may be made of the same material, or may be made of different materials from each other. As the material of the ring electrode 256, for example, a metal mainly containing copper, aluminum, or the like can be used, but the material is not limited to this, and for example, graphite or the like may be used.

The guard ring 254 is connected to the filament connecting pin 52a in the same manner as the guard ring 54. Further, the ring electrode 256 is connected to the Wenert connection pin 52b in the same manner as the ring electrode 56. That is, the potential of the guard ring 254 is the filament potential, and the potential of the ring electrode 256 is the Wenert potential. The potential of the ring electrode 256 is lower than the potential of the guard ring 254.

In this modification, since the electron gun 250 is configured as described above, substantially the same effect as that of the electron gun 50 according to the first embodiment described above can be obtained.

In particular, in this modification, since the guard ring 254 is provided with the protruding portion 254a, the electric field is weakened around the side surface of the lower portion of the support portion 51c. Further, since the ring electrode 256 is provided with the tubular portion 256d, the equipotential lines between the upper end portion of the guard ring 254 and the ring electrode 56 are substantially parallel to the side surface of the support portion 51c. That is, the upper part and the lower part of the side surface of the support portion 51c are close to the same potential, and the force in the direction along the creeping surface does not act on the electrons. Further, the potential of the tubular portion 256d is lower than the potential of the protruding portion 254a. Since the electron gun cover 58 is connected to the ground potential, the potential on the side surface of the support portion 51c and the potential on the protruding portion 254a are approximately the same height. Therefore, the electric field from the protruding portion 254a of the guard ring 254 toward the side surface of the support portion 51c is also very weak. Therefore, the occurrence of creeping discharge can be more reliably prevented, and the withstand voltage performance of the electron gun 250 can be further improved.

FIG. 5 is a diagram schematically showing a schematic configuration of an electron gun 350 according to still another modification of the first embodiment.

As shown in FIG. 5, the electron gun 350 differs from the electron gun 50 in the following points. An annular groove 351e recessed from the surface of the insulator 351 is formed on the surface (boundary surface in contact with the vacuum) of the insulator (an example of an insulating member and a solid dielectric) 351 on the electron gun chamber 10a side. The groove portion 351e is formed, for example, on the outer peripheral surface of the support portion 51c, the lower surface of the upper plate portion 51a, or the inner peripheral surface of the peripheral wall portion 51b. The groove portion 351e is formed so as to divide the creepage surface from the guard ring 54 to the vacuum chamber wall 10 and block the creepage discharge path R. For example, three groove portions 351e are formed. The position and number of the groove portions 351e are not limited to this. In addition, the electron gun 350 is configured in the same manner as the electron gun 50, except for the parts not particularly described below.

Since the groove portion 351e is formed in the insulator 351 in this way, the path R of the creeping discharge goes through the path that becomes the electric field in the opposite direction. Therefore, the effect of suppressing the occurrence of creeping discharge can be further obtained.

The number of groove portions 351e may be one or two, or may be more than four. The shape of the bottom of the recess of the groove portion 351e is a rounded shape, but the shape is not limited to this.

[Second Embodiment]
The configuration of the SEM electron gun in the second embodiment will be described. The description of the member having the same shape or function as the electron gun in the first embodiment may be omitted below.

FIG. 6 is a diagram schematically showing a schematic configuration of an electron gun 450 of an SEM, a transmission electron microscope, and an open-type X-ray apparatus according to a second embodiment of the present invention.

The electron gun 450 is a so-called Schottky type.

As shown in FIG. 6, the electron gun 450 is roughly divided into both an electron gun chamber 10a side and an atmospheric pressure side outside the electron gun chamber 10a. The electron gun chamber 10a of the electron gun 450 is surrounded by an insulator (an example of an insulating member and a solid dielectric) 451 and an O-ring 50a, a chamber wall 10 and a cover 458, and a vacuum environment is maintained. In the electron gun chamber 10a, an electron source 411, a suppressor electrode (an example of a limiting electrode that limits the amount of charged particles) 413, a guard ring 454, and an anode 414d are arranged. The anode 414d and the chamber wall 10 are connected to a ground potential.

The insulator 451 has a bottomed tubular shape that tapers downward, and substantially the entire insulator is a support portion 451c that protrudes in the electron emitting direction. At the bottom of the insulator 451, four connecting pins (high pressure introduction connecting pin; an example of a penetrating member) 452 (two emitter connecting pins (an example of a first penetrating member) 452a, a suppressor connecting pin (a second penetrating member). Example) 452b and the guard ring connecting pin 452c) are arranged so as to penetrate from the electron gun chamber 10a side to the atmospheric pressure side. Each connection pin 452 is connected to the high voltage introduction cable 14a.

In the second embodiment, the inside of the insulator 451 is a recess on the atmospheric pressure side. The side surface portion of the insulator 451 has a substantially uniform thickness except for a portion described later. The inside of the insulator 451 is filled with silicone rubber 459, resin or the like. As a result, creeping discharge does not occur from the high-voltage portion.

The electron source 411 has an emitter 411a. Both ends of the emitter 411a are attached to two emitter connecting pins 452a. A suppressor electrode 413 is arranged near the tip of the emitter 411a. The suppressor electrode 413 is electrically connected to the suppressor connection pin 452b. The suppressor electrode 413 has a suppressor potential slightly lower than the voltage (emitter potential) applied to the emitter 411a. The suppressor electrode 413 is an electrode that is biased to a negative voltage with respect to the electron source 411. A voltage is applied to the emitter 411a by the acceleration power supply 14, and electrons are emitted from the tip of the emitter 411a.

The guard ring 454 is attached to the lower part of the insulator 451 and is arranged at a position closer to the insulator 451 than the electron source 411. The guard ring 454 has a projecting portion 454a projecting upward from the side portion and a first anode portion 454b extending downward from the side portion.

The protrusion 454a is formed so as to surround the outer side of the lower portion of the insulator 451. The upper end portion of the protruding portion 454a is formed to be rounded so that the cross section has a semicircular shape, for example. The vertical position of the upper end of the protrusion 454a is substantially the same as or above the inner bottom of the insulator 451.

The first anode portion 454b is arranged so as to surround the electron source 411 and the suppressor electrode 413, and is configured so that the primary electron beam 12 is emitted from the lower central portion. The guard ring 454 is given an anodic potential higher than the emitter potential.

In the second embodiment, the portion of the inner surface of the insulator 451 near the bottom is formed so as to form a substantially vertical surface. A ring electrode 456 formed in a cylindrical shape along the inner surface of the insulator 451 is arranged at this portion. That is, the ring electrode 456 is arranged above the inner bottom of the insulator 451. As the material of the ring electrode 456, for example, a metal mainly containing copper, aluminum, or the like can be used, but the material is not limited to this, and a conductive material such as graphite may be used.

The ring electrode 456 may be formed by inserting a preformed one into the insulator 451 and may be arranged, or may be formed as, for example, a metallized electrode. The ring electrode 456 is not limited to a thin cylindrical one as shown in FIG. 6, and may have a large thickness. The inner surface of the insulator 451 may be formed so as to be inclined even at a portion near the bottom. Further, the radial dimension of the ring electrode 456 (horizontal direction in FIG. 6) may not be substantially constant. For example, the ring electrode 456 may be formed so that the outer surface is formed along the surface of the insulator 451 and the inner surface is substantially perpendicular to the horizontal plane.

The ring electrode 456 is electrically connected to the suppressor connection pin 452b and has a suppressor potential. In the second embodiment, a portion of the lower portion of the ring electrode 456 extends toward the suppressor connection pin 452b and is connected to the suppressor connection pin 452b.

As described above, the emitter 411a of the electron source 411 has an emitter potential, and the guard ring 454 has an anode potential higher than the emitter potential. Further, the ring electrode 456 and the suppressor electrode 413 have a suppressor potential slightly lower than the emitter potential. For example, the emitter potential is -100 kV. The anodic potential is minus 97 kV. The suppressor potential is set to -100.3 kV.

As described above, the anodic potential is applied to the guard ring 454, and the suppressor potential lower than the anodic potential is applied to the ring electrode 456. Therefore, the potential gradient in the region near the guard ring 454 and above the guard ring 454. That is, the electric potential strength is weakened. Since the electric field from the protruding portion 454a of the guard ring 454 toward the insulator 451 becomes weak, it becomes difficult for electrons to be emitted toward the insulator 451. Alternatively, the surface potential of the insulator 451 in the vicinity of the guard ring 454 becomes lower than the potential of the guard ring 454, and electron emission from the guard ring 454 is hindered. This region is a region in which electrons are likely to be emitted from the guard ring 454 toward the insulator 451 in the conventional technique. Therefore, when a high voltage is applied to the electron source 411, the electron emission phenomenon that may cause creepage discharge is less likely to occur in the past. Electron emission is less likely to be chained on the surface portion of the insulator 451 and generation of creeping discharge is prevented. Therefore, the withstand voltage performance of the electron gun 50 can be improved. Therefore, it is possible to achieve both the miniaturization of the electron gun 450 and the improvement of the withstand voltage performance.

[Other]
Although the present invention has been described in accordance with the above embodiments, the description and drawings of this disclosure should not be understood to limit the invention. An electron gun may be configured by appropriately combining the above-mentioned feature points of each part. By arranging an electrode having a potential lower than the potential of the guard ring on the opposite side of the guard ring with respect to the insulator, it is possible to prevent the occurrence of creeping discharge as described above.

The shape of details such as insulators, guard rings, and ring electrodes can be changed as appropriate to the extent that the above effects can be obtained.

The ring electrode and guard ring do not necessarily have to be electrically connected to the high voltage introduction connection pin. A voltage may be applied from another power source, and the ring electrode may be configured to have a lower potential than the guard ring as a whole.

The electron gun is not limited to the configuration of the above-described embodiment. For example, on the vacuum side, a ring member having substantially the same outer diameter as the ring electrode may be provided between the insulator and the Wenert electrode to prevent the generation of electric discharge.

As the material of the insulator, various insulating materials such as glass and resin can be used as the insulating member instead of ceramics such as alumina.

From the above description, it can be understood that the present invention can be easily applied to charged particle application devices such as EPMA, FIB, and electron beam drawing devices, which are charged particle beam devices.

Further, in the above-mentioned electron gun, an insulator that divides two upper and lower regions (for example, a first region on the electron gun chamber side (vacuum side) and a second region on the atmospheric pressure side) and the two regions thereof. An insulating structure consisting of a high-pressure introduction connection pin that penetrates the insulator so that it leads to the insulator, a guard ring placed below the insulator, and a ring electrode placed above the insulator and given a lower potential than the guard ring. It may be used for things other than electron guns. Even in this case, the effect of preventing the occurrence of creeping discharge can be obtained. For example, such an insulating structure can be used as a connector portion of a high-voltage cable for extracting electric power from a high-voltage power source filled with insulating gas or insulating oil. In this case, for example, a region filled with insulating gas or insulating oil may be arranged below the insulator, and power can be taken out from the region above the insulator through a high-voltage introduction connection pin connected to the high-voltage power supply. it can.

Further, the insulating structure may be as shown below. An insulating structure capable of achieving a high withstand voltage can be used for various applications using a high-voltage power supply.

FIG. 7 is a diagram illustrating a first example of an insulating structure. FIG. 8 is a side view illustrating the first example of the insulating structure.

As shown in FIG. 7, the insulating structure 501 has a flat plate-shaped solid dielectric 551. A first electrode 554 and a second electrode 510 are arranged on the upper surface of the solid dielectric 551. A third electrode 556 is arranged on the lower surface of the solid dielectric 551. The upper surface of the solid dielectric 551 is an interface 551x, which is an interface in contact with vacuum. The boundary surface 551x may be an interface in contact with a gas or liquid. The surface of the solid dielectric other than the boundary surface 551x may be covered with, for example, silicone rubber.

The first electrode 554 and the second electrode 510 are arranged at positions separated from each other so as to be in contact with the boundary surface 551x (that is, in contact with the solid dielectric material 551). That is, on the surface of the solid dielectric 551, the portion located between the first electrode 554 and the second electrode 510 is the boundary surface 551x. The third electrode 556 is arranged at a position distant from the boundary surface 551x downward, that is, at a position distant from the solid dielectric 551 side. In other words, the third electrode 556 is arranged on the solid dielectric 551 side with respect to the boundary surface 551x so as not to come into contact with the boundary surface 551x. The third electrode 556 is arranged closer to the first electrode 554.

The relationship between the potential Va of the first electrode 554, the potential Vb of the second electrode 510, and the potential Vc of the third electrode 556 is Vc <Va <Vb. Therefore, the equipotential lines around the portion of the boundary surface 551x between the first electrode 554 and the second electrode 510 are shown by a two-dot chain line in FIG. At the boundary surface 551x portion, the electric field does not become a uniform direction between the first electrode 554 and the second electrode 510 due to the influence of the third electrode 556. Therefore, creeping discharge from the first electrode 554 to the second electrode 510 is less likely to occur. The potential Vb may be the ground potential.

FIG. 9 is a diagram illustrating a second example of the insulating structure.

As shown in FIG. 9, the insulating structure 601 has a structure in which the first electrode 654, the second electrode 610, the third electrode 656, and the solid dielectric 651 are housed in the case 659. ing. The inside of the case 659 is in a vacuum state or a state filled with a gas or a liquid.

The first electrode 654, the second electrode 610, the third electrode 656, and the solid dielectric 651 each have a substantially axisymmetric shape with respect to the same central axis (in FIG. 9). Shows a cross section in a plane passing through its central axis). That is, the disk-shaped first electrode 654 is arranged so as to be in contact with the lower part of the columnar solid dielectric 651. The disk-shaped second electrode 610 with an open central portion is arranged so as to be in contact with the upper portion of the solid dielectric material 651. The outer diameter of the first electrode 654 and the outer diameter of the second electrode 610 are larger than the diameter of the solid dielectric 651. The side peripheral surface of the solid dielectric 651 is an interface 651x in contact with any of vacuum, gas, and liquid. That is, on the surface of the solid dielectric 651, the portion located between the first electrode 654 and the second electrode 610 is the boundary surface 651x. The third electrode 656 is arranged inside the solid dielectric 651, that is, at a position away from the boundary surface 651x toward the solid dielectric 651. In other words, the third electrode 656 is arranged on the solid dielectric 651 side with respect to the boundary surface 651x so as not to come into contact with the boundary surface 651x. The third electrode 656 is arranged closer to the first electrode 654.

The relationship between the potential Va of the first electrode 654, the potential Vb of the second electrode 610, and the potential Vc of the third electrode 656 is Vc <Va <Vb. Further, the case 659 is connected to the ground potential. Therefore, at the boundary surface 651x portion, the electric field does not become a uniform direction between the first electrode 654 and the second electrode 610 due to the influence of the third electrode 656. Electrons exiting the first electrode 654 and heading toward the second electrode 610 are stopped or impeded by the third electrode 656. Therefore, creeping discharge (for example, discharge in the path shown by the dotted line in FIG. 9) from the first electrode 654 to the second electrode 610 is less likely to occur. The potential Vb may be the ground potential.

The potentials of the electrodes 610, 654, 656 are given by a voltage divider circuit 605 using two (or three or more) resistors. Therefore, the insulating structure 601 can be used by connecting to one power source.

The insulating structure can be used, for example, in a gas insulating device, a high-voltage relay, an X-ray tube, a high-voltage portion of an open X-ray source, a connector portion of a high-voltage power supply, or a cryostron.

FIG. 10 is a diagram illustrating a third example of an insulating structure.

As shown in FIG. 10, the insulating structure 701 has a structure in which the first electrode 754, the second electrode 710, the third electrode 756, and the solid dielectric 751 are housed in the case 759. ing. The inside of the case 759 is filled with, for example, insulating rubber, insulating resin, insulating liquid, insulating gas, or the like, except for the above-mentioned structural portion.

The first electrode 754, the second electrode 710, the third electrode 756, and the solid dielectric 751 each have a substantially axisymmetric shape with respect to the same central axis (in FIG. 10). Shows a cross section in a plane passing through its central axis). That is, the disk-shaped first electrode 754 is arranged so as to be in contact with the lower part of the cylindrical solid dielectric 751. The disk-shaped second electrode 710 is arranged so as to be in contact with the upper part of the solid dielectric 751. The outer diameter of the first electrode 754 and the outer diameter of the second electrode 710 are larger than the diameter of the solid dielectric 751. The portion of the solid dielectric 751 sealed by the first electrode 754 and the second electrode 710 is in a vacuum state or a state filled with a gas or liquid. The inner peripheral surface of the solid dielectric 751 is an interface 751x in contact with any of vacuum, gas, and liquid. That is, on the surface of the solid dielectric 751, the portion located between the first electrode 754 and the second electrode 710 is the boundary surface 751x. The third electrode 756 is annular and is arranged outside the outer peripheral portion of the solid dielectric 751, that is, at a position separated from the boundary surface 751x toward the solid dielectric 751. In other words, the third electrode 756 is arranged on the solid dielectric 751 side with respect to the boundary surface 751x so as not to come into contact with the boundary surface 751x. The third electrode 756 is arranged closer to the first electrode 754.

The relationship between the potential Va of the first electrode 754, the potential Vb of the second electrode 710, and the potential Vc of the third electrode 756 is Vc <Va <Vb. Therefore, at the boundary surface 751x portion, the electric field does not become a uniform direction between the first electrode 754 and the second electrode 710 due to the influence of the third electrode 756. Therefore, creeping discharge (for example, discharge in the path shown by the dotted line in FIG. 10) from the first electrode 754 to the second electrode 710 is less likely to occur.

If the movement of positive ions from the second electrode 710 to the first electrode 754 causes an electric discharge, a third electrode 756 is placed in a portion closer to the second electrode 710. A similar additional electrode (another example of the third electrode) 756b may be provided. By giving the additional electrode 756b a potential higher than the potential Vb of the second electrode 710, the movement of positive ions can be prevented. The additional electrode 756b may be arranged without providing the third electrode 756. At this time, the potential Va may be the ground potential.

The embodiments and modifications described above should be considered exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

10 Vacuum chamber wall (an example of the second electrode)
10a electron gun chamber (an example of the first area)
11,411 Electron source 12 Charged particle beam (primary electron beam)
13 Wenert electrode (an example of a limiting electrode that limits the amount of charged particles)
14 Acceleration power supply 14a High voltage introduction cable 14d Anode plate 18 Objective lens 19 Secondary electron detector 20 Detector (semiconductor detector, Robinson detector or MCP detector)
21 Signal electrons 21a Secondary electrons 21b Reflected electrons 23 Sample 41 Objective lens power supply 50, 250, 350, 450 Electron gun (example of insulation structure)
51,251,351,451 insulators (an example of insulating member and solid dielectric)
51c, 451c Support 52a Filament connection pin (example of first penetrating member)
52b Wenert connection pin (an example of a second penetrating member)
54,254,454 Guard ring (an example of the first electrode)
56,256,456 Ring electrode (an example of a third electrode)
100 SEM (Example of charged particle beam application device)
413 Suppressor electrode (an example of a limiting electrode that limits the amount of charged particles)
452 connection pin (example of penetrating member)
452a Emitter connection pin (example of first through member)
452b Suppressor connection pin (an example of a second penetrating member)
452c Guard ring connection pin 501,601,701 Insulation structure 510,610,710 Second electrode 551,651,751 Solid dielectric 551x, 651x, 751x Boundary surface 554,654,754 First electrode 556,656,756 Third electrode 756b Additional electrode (an example of the third electrode)

Claims (19)

An insulating structure that is used by being connected to a high-voltage power supply.
With the first electrode
A second electrode having a higher potential than the first electrode and
A solid dielectric material in contact with the first electrode and the second electrode,
With a third electrode
The first electrode, the second electrode, and the third electrode are connected to the high voltage power supply.
On the surface of the solid dielectric, the portion located between the first electrode and the second electrode is a boundary surface in contact with any of vacuum, gas, and liquid.
The third electrode is arranged at a position away from the boundary surface on the solid dielectric side.
An insulating structure in which the potential of the third electrode is lower than the potential of the first electrode. An insulating structure that is used by being connected to a high-voltage power supply.
With the first electrode
A second electrode having a higher potential than the first electrode and
A solid dielectric material in contact with the first electrode and the second electrode,
With a third electrode
The first electrode, the second electrode, and the third electrode are connected to the high voltage power supply.
On the surface of the solid dielectric, the portion located between the first electrode and the second electrode is a boundary surface in contact with any of vacuum, gas, and liquid.
The third electrode is arranged at a position away from the boundary surface on the solid dielectric side.
An insulating structure in which the potential of the third electrode is higher than the potential of the second electrode. It is an insulating structure that is used by being connected to a high-voltage power supply.
With the first electrode
A second electrode having a higher potential than the first electrode and
A solid dielectric material in contact with the first electrode and the second electrode,
With a third electrode
On the surface of the solid dielectric, the portion located between the first electrode and the second electrode is a boundary surface in contact with any of vacuum, gas, and liquid.
The third electrode is arranged at a position away from the boundary surface on the solid dielectric side.
The potential of the third electrode is lower than the potential of the first electrode.
Wherein the first electrode, the second electrode, the third electrode, each of said solid dielectric, has a substantially axisymmetric shape with respect to the same central axis, insulation structure .. It is an insulating structure that is used by being connected to a high-voltage power supply.
With the first electrode
A second electrode having a higher potential than the first electrode and
A solid dielectric material in contact with the first electrode and the second electrode,
With a third electrode
On the surface of the solid dielectric, the portion located between the first electrode and the second electrode is a boundary surface in contact with any of vacuum, gas, and liquid.
The third electrode is arranged at a position away from the boundary surface on the solid dielectric side.
The potential of the third electrode is higher than the potential of the second electrode.
An insulating structure in which the first electrode, the second electrode, the third electrode, and the solid dielectric each have a substantially axisymmetric shape with respect to the same central axis. The insulating structure according to any one of claims 1 to 4 , wherein the first electrode or the second electrode has a ground potential. An insulating structure that is used by being connected to a high-voltage power supply.
With the first electrode
A second electrode having a higher potential than the first electrode and
A solid dielectric material in contact with the first electrode and the second electrode,
With a third electrode
On the surface of the solid dielectric, the portion located between the first electrode and the second electrode is a boundary surface in contact with any of vacuum, gas, and liquid.
The third electrode is arranged at a position away from the boundary surface on the solid dielectric side.
The potential of the third electrode is lower than the potential of the first electrode.
The solid dielectric having a groove formed so as to divide the boundary surface of the first electrode to the second electrode, insulation structure. It is an insulating structure that is used by being connected to a high-voltage power supply.
With the first electrode
A second electrode having a higher potential than the first electrode and
A solid dielectric material in contact with the first electrode and the second electrode,
With a third electrode
On the surface of the solid dielectric, the portion located between the first electrode and the second electrode is a boundary surface in contact with any of vacuum, gas, and liquid.
The third electrode is arranged at a position away from the boundary surface on the solid dielectric side.
The potential of the third electrode is higher than the potential of the second electrode.
The solid dielectric has an insulating structure having a groove formed so as to divide the boundary surface from the first electrode to the second electrode. A charged particle gun that emits charged particles and has the insulating structure according to any one of claims 1 to 7 .
The solid dielectric has a support that supports a charged particle source.
The first electrode is a guard ring arranged so as to be in contact with the support portion.
The second electrode is a vacuum chamber wall that is in contact with the solid dielectric and is arranged so as to surround the charged particle source.
The third electrode is a ring electrode that is arranged on the opposite side of the guard ring with respect to the solid dielectric and has a ring shape.
Each of the charged particle guns has conductivity and has a plurality of penetrating members penetrating the solid dielectric.
The charged particle source is connected to a pair of penetrating members among the plurality of penetrating members.
The guard ring is a charged particle gun connected to any of the plurality of penetrating members. The charged particle gun according to claim 8 , wherein the vacuum chamber wall is connected to a ground potential. The charged particle gun according to claim 8 or 9 , wherein one of the pair of penetrating members to which the charged particle source is connected and the guard ring are electrically connected. The charged particle gun according to claim 8 or 9 , wherein the guard ring is connected to a potential higher than the potential of the charged particle source. The charged particle gun according to claim 11 , wherein the guard ring is electrically connected to a first anode portion that draws the charged particle source electrons from the charged particle source. Further comprising a limiting electrode connected to any of the plurality of penetrating members and limiting the amount of the charged particles emitted from the charged particle gun.
The charged particle gun according to any one of claims 8 to 12 , wherein the penetrating member connected to the limiting electrode is electrically connected to the third electrode. The charged particle gun according to any one of claims 8 to 13 , wherein the outermost peripheral portion of the ring electrode is located outside the peripheral edge portion of the guard ring. The solid dielectric is an insulating member and
The charged particle gun according to any one of claims 8 to 14 , wherein the support portion is formed so as to project in the emission direction of the charged particles. The guard ring has a concave shape that covers the protruding end of the support.
The charged particle gun according to claim 15 , wherein the upper end portion of the guard ring has a round chamfer shape having an arcuate portion in a cross section. The support portion has a recess that opens in a direction opposite to the emission direction of the charged particles.
The charged particle gun according to claim 16 , wherein the ring electrode is arranged inside the recess. The charged particle gun according to any one of claims 8 to 17 , wherein the potential of each of the plurality of penetrating members is given by a voltage dividing circuit using two or more resistors. The charged particle gun according to any one of claims 8 to 18 .
An objective lens that focuses the charged particle beam emitted from the charged particle gun on the sample, and
A charged particle beam application device including a detector that detects reflected electrons emitted from the sample when the charged particle beam is incident.

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