JP2021096942A - Electron gun and electronic equipment - Google Patents

Abstract

To provide an electron gun having a nanowire emitter for adjusting the irradiation position of an electron beam without breaking vacuum, and electronic equipment using the same.SOLUTION: An electron gun includes: a nanowire emitter for emitting an electron beam from the end; a stage having a first spherical crown-shaped shell and a second spherical crown-shaped shell, in which the first spherical crown-shaped shell is fixed to the stage, the second spherical crown-shaped shell is stacked on the fixed first spherical crown-shaped shell so as to slide with respect to the first spherical crown-shaped shell, a concave surface side and a convex surface side of the stacked first spherical crown-shaped shell and the second spherical crown-shaped shell are exposed to vacuum and atmosphere, respectively, and the nanowire emitter is attached to the stage so that an end portion thereof serves as the concave surface side; and a housing for separating the vacuum and the atmosphere from each other and holding the stage via an elastic portion.SELECTED DRAWING: Figure 2

Description

The present invention relates to electron guns and electronic devices.

In order to obtain high-resolution and high-brightness observation images, sharpened needle-like materials have been used as ion sources in electron guns and focused ion beam devices in electron microscopes, and various improvements have been made.

There is an electron source using such a sharpened acicular substance (see, for example, Patent Document 1). According to Patent Document 1, there is a technique of attaching a needle-like substance (emitter) such as carbon nanotubes or rare earth hexaboride nanowires to a conductive tip member to reduce the deviation of an electron beam.

However, in Patent Document 1, it is difficult to further adjust the irradiation position of the electron beam without breaking the vacuum after installing the emitter.

Japanese Unexamined Patent Publication No. 2016-110748

An object of the present invention is to provide an electron gun provided with a nanowire emitter that adjusts an irradiation position of an electron beam without breaking a vacuum, and an electronic device using the same.

The electron gun according to the present invention is a stage including a nanowire emitter that emits an electron beam from an end, a first crown-shaped shell, and a second crown-shaped shell, wherein the first crown-shaped shell is provided. It is fixed to the stage, and the second coronal shell is overlapped so as to slide with respect to the fixed first coronal shell, and the overlapped first coronal shell is formed. The concave and convex sides of the shell and the second spherical shell are exposed to vacuum and air, respectively, and the nanowire emitter is attached to the stage so that its ends are on the concave side. A housing that separates the vacuum from the atmosphere and holds the stage via an expansion / contraction portion is provided, thereby solving the above-mentioned problems.
The first crown-shaped shell and the second crown-shaped shell may be a part of a sphere having a radius R (where R satisfies 1 mm ≦ R ≦ 1000 mm).
The lower surface of the first crown-shaped shell and the second crown-shaped shell may be a circle having a radius a (where a satisfies 1 mm ≦ a ≦ R).
The height h from the lower surface to the side surface of the first ball-shaped shell and the second ball-crowned shell may satisfy 1 mm ≦ H <2 × R.
The telescopic portion may have a bellows shape.
The bellows shape may be formed of a material selected from the group consisting of metal materials, rubber-based materials and thermoplastic elastomer materials.
The telescopic portion may maintain a compression force between the first crown-shaped shell and the second crown-shaped shell in a range of 0.1 N or more and 10 N or less under vacuum.
The stage may be attached to the second crown-shaped shell and may further include four strings that control the sliding of the second crown-shaped shell.
The four strings may be evenly spaced in the second coronal shell.
A lubricant may be further included between the first coronal shell and the second coronal shell.
The nanowire emitter may _{be a needle-like material selected from the group consisting of lanthanum hexaboride (LaB 6} ), hafnium carbide (HfC), carbon nanotubes, boron nitride nanotubes, and boron nitride nanotubes.
It may be a cold cathode field emission electron gun or a Schottky electron gun.
The electronic device according to the present invention includes the above-mentioned electron gun, thereby solving the above-mentioned problems.
The electronic device may be selected from the group consisting of a scanning electron microscope, a transmission electron microscope, a scanning transmission electron microscope, an Auger electron spectroscope, an electron energy loss spectroscope, and an energy dispersion electron spectroscope.

In the electron gun of the present invention, as a stage on which the nanowire emitter is attached, the first and second crown-shaped shells are superposed so that the second crown-shaped shell slides against the first crown-shaped shell. The stage is held by the housing through the telescopic portion, which allows the end of the nanowire emitter to emit an electron beam. As a result, even after the emitter is installed, the delicate irradiation position of the electron beam can be adjusted without breaking the vacuum, and the surface of the nanowire emitter can be kept clean.

Such an electron gun can be adopted in electronic devices such as a scanning electron microscope, a transmission electron microscope, a scanning transmission electron microscope, an Auger electron spectroscope, an electron energy loss spectroscope, and an energy dispersion electron spectroscope.

Perspective view showing the electron source of the present invention XX'cross-sectional view of FIG. Enlarged view of the first and second coronal shells Enlarged view of another first and second coronal shell Sectional drawing showing another electron source of this invention Sectional drawing showing yet another electron source of this invention Schematic diagram showing a method of adjusting the irradiation position of an electron beam in the X-axis direction using the electron source of the present invention. Schematic diagram showing a method of adjusting the irradiation position of an electron beam in the Y-axis direction using the electron source of the present invention. The figure which shows the irradiation position of the electron beam using the electron gun of Example 1.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same elements are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 1 is a perspective view showing an electron source of the present invention.
FIG. 2 is a cross-sectional view taken along the line XX'of FIG.

The electron gun 100 of the present invention partitions a vacuum and an atmosphere from a stage 130 including a nanowire emitter 110 that emits an electron beam from an end, a first crown-shaped shell 120a and a second crown-shaped shell 120b. The stage 130 is provided with a housing 150 that holds the stage 130 via the telescopic portion 140.

Further, the first sphere-shaped shell 120a (upper hemisphere in FIG. 1) is fixed to the stage 130, and the second sphere-shaped shell 120b (lower hemisphere in FIG. 1) is fixed. It is overlapped so as to slide with respect to the first spherical crown-shaped shell 120a. Here, the concave side of the two stacked first and second crown-shaped shells 120a and b is exposed to vacuum, and the convex side is exposed to the atmosphere.

The nanowire emitter 110 is attached to the stage 130 so that its ends are on the concave side of the two stacked first and second crown-shaped shells 120a, b. Specifically, the nanowire emitter 110 is attached to the concave side of the second spherical shell 120b so as to connect to an electrode 160 described later.

The nanowire emitter 110 is not particularly limited as long as it is made of a needle-like substance and can emit electrons, but examples thereof include lanthanum hexaboride (LaB ₆ ), hafnium carbide (HfC), carbon nanotubes, and boron nitride. Examples thereof include needle-like substances selected from the group consisting of boron nanotubes and boron nitride nanotubes. These are materials that are manufactured or available and are known as electron source emitters.

Of the two stacked first and second coronal shells 120a and b, the second coronal shell 120b (lower hemisphere in FIG. 1) slides, so that the electron beam of the nanowire emitter 110 Allows the end to turn. Further, since the stage 130 is held via the telescopic portion 140, it is possible to finely adjust the irradiation position of the electron beam without breaking the vacuum.

Since the YY'cross-sectional view of FIG. 1 is the same as that of FIG. 2, the description thereof will be omitted.

FIG. 3A is an enlarged view of the first and second coronal shells.
FIG. 3B is an enlarged view of another first and second coronal shell.

In FIGS. 3A and 3B, for the sake of clarity, the thickness of the second coronal shell 120b is increased, and the first coronal shell 120a and the second coronal shell 120b are shown. Although it is shown that they overlap with each other, it is assumed that the thickness of the first spherical shell 120b is thin and they overlap with each other substantially without separation. Further, the first spherical shell 120a may be integrated with the stage 130 as shown in FIGS. 3A and 3B.

The first crown-shaped shell 120a and the second crown-shaped shell 120b are both part of a sphere having a radius R. As a result, the second crown-shaped shell 120b easily slides with respect to the fixed first crown-shaped shell 120a. The radius R preferably satisfies 1 mm ≦ R ≦ 1000 mm. More preferably, the radius R satisfies 5 mm ≦ R ≦ 100 mm.

The lower surfaces of the first and second crown-shaped shells 120a and 120b are preferably circles with a radius a, where a satisfies 1 mm ≦ a ≦ R. When R is 1 mm, a is 1 mm. Within this range, the second crown-shaped shell 120b easily slides with respect to the fixed first crown-shaped shell 120a. More preferably, a satisfies 1 mm ≦ a ≦ 100 mm.

The height h from the lower surface to the side surface of the first and second coronal shells 120a and 120b preferably satisfies 1 mm ≦ H <2 × R. Within this range, the second crown-shaped shell 120b easily slides with respect to the fixed first crown-shaped shell 120a. More preferably, H satisfies 1 mm ≦ H ≦ 100 mm. Note that FIG. 3A schematically shows a case where H is H ≦ R, and FIG. 3B schematically shows a case where H is R <H <2 × R.

The telescopic portion 140 may have a bellows shape as shown in FIGS. 1 and 2. This allows expansion and contraction. As the member forming the bellows shape, a metal material, a rubber-based material, or a thermoplastic elastomer material can be used. Examples of the metal material include stainless steel and steel. Examples of the rubber-based material include silicon rubber and fluororubber. Examples of the thermoplastic elastomer material include an olefin-based thermoplastic elastomer and a polybutadiene-based thermoplastic elastomer.

Further, the telescopic portion 140 preferably maintains a compression force between the first crown-shaped shell 120a and the second crown-shaped shell 120b in a range of 0.1 N or more and 10 N or less under vacuum. To work. As a result, even under vacuum, the second crown-shaped shell 120b easily slides with respect to the fixed first crown-shaped shell 120a.

FIG. 4 is a cross-sectional view showing another electron source of the present invention.

Another electron source 400 of the present invention is the same as the electron source 100 of FIGS. 1 and 2 except that it contains a lubricant 410 between the first crown-shaped shell 120a and the second crown-shaped shell 120b. Therefore, the description of common elements will be omitted. By including the lubricant 410, the second crown-shaped shell 120b slides more easily with respect to the fixed first crown-shaped shell 120a. Such a lubricant 410 is not particularly limited, and examples thereof include a silicon spray and a graphite spray.

FIG. 5 is a cross-sectional view showing still another electron source of the present invention.

Yet another electron source 500 is attached to the second crown-shaped shell 120b and further comprises four strings 510a-510d that control the sliding of the second crown-shaped shell 120b. Since it is the same as the electron source 100 of 2, the description of common elements will be omitted. In FIG. 5, since it corresponds to the XX'cross-sectional view of FIG. 1, only two strings 510a and 510b out of the four strings are shown, but also on the side corresponding to the YY'cross-sectional view of FIG. It should be understood that the two strings 510c and 510d are also located. That is, the four strings are located on the second coronal shell 120b at 90 ° intervals, i.e. evenly spaced. In the present specification, the strings are not limited to strings, but rod-shaped ones having rigidity are also intended.

By pushing / pulling such strings, the second crown-shaped shell 120b can be slid with high accuracy with respect to the fixed first crown-shaped shell 120a. That is, the second spherical shell 120b can be slid by operating the strings manually or by computer control via an actuator or the like. In particular, if computer control is performed, the irradiation position of the electron beam from the nanowire emitter 110 can be controlled with high accuracy in the X-axis direction and / or the Y-axis direction on the order of micrometers to millimeters.

Of course, the strings 510a to 510d of FIG. 5 may be attached to the electron source 400 of FIG.

The electron guns 100, 400, and 500 are provided with an electrode 160, and the electrode 160 may be connected to a drawer power source (not shown) and an acceleration power source (not shown). The electron guns 100, 400, and 500 further include an extraction electrode (not shown) and an acceleration electrode (not shown), between the nanowire emitter 110 and the extraction electrode, and between the nanowire emitter 110 and the acceleration electrode. It may be possible to apply a voltage to the.

When the electron guns 100, 400, and 500 are cold cathode field emission electron guns, the electrode 160 may be connected to a flash power source, and in the case of a Schottky electron gun, it may be connected to a heating power source.

Next, a method of adjusting the irradiation position of the electron beam using the electron gun 500 of the present invention will be described.
FIG. 6 is a schematic view showing a method of adjusting the irradiation position of the electron beam in the X-axis direction using the electron source of the present invention.
FIG. 7 is a schematic view showing a method of adjusting the irradiation position of the electron beam in the Y-axis direction using the electron source of the present invention.

First, the nanowire emitter 110 is installed, the electron gun 500 is evacuated, and the irradiation position of the electron beam from the nanowire emitter 110 in the initial state is confirmed. The fluorescent plate is irradiated with an electron beam from the electron gun 500 in which the strings 510a to 510d are in the initial state (that is, h = 0), and the light emitting position at that time is recorded. Here, the irradiation position 610 is the irradiation position in the initial state.

Strings 510a to 510d are used to center the irradiation position 610 at the intersection of the X-axis and the Y-axis. As shown in the right figure of FIG. 6, when the strings 510a shifts by −h (mm) and the strings 510b shifts by + h (mm), the irradiation position 610 further moves in the X-axis direction to reach the irradiation position 620. In this case, the inclination angle of the nanowire emitter 110 in the X-axis direction is + Θx.

On the other hand, as shown in the left figure of FIG. 6, when the strings 510a shifts by + h (mm) and the strings 510b shifts by −h (mm), the irradiation position 610 further moves in the −X axis direction to reach the irradiation position 630. .. In this case, the inclination angle of the nanowire emitter 110 in the X-axis direction is −Θx.

Similarly, as shown in the right figure of FIG. 7, when the strings 510c are shifted by −h (mm) and the strings 510d are shifted by + h (mm), the irradiation position 610 is further moved in the Y-axis direction to become the irradiation position 710. .. In this case, the inclination angle of the nanowire emitter 110 in the Y-axis direction is + Θy.

Further, as shown in the left figure of FIG. 7, when the strings 510c shifts by + h (mm) and the strings 510d shifts by −h (mm), the irradiation position 610 further moves in the −Y axis direction to reach the irradiation position 720. .. In this case, the inclination angle of the nanowire emitter 110 in the Y-axis direction is −Θy.

By appropriately combining the shifts of the strings 510a to 510d, the irradiation position 610 in the initial state can be moved to the center where the X-axis and the Y-axis intersect without breaking the vacuum. The shift amount (moving distance) and the inclination angle of the emitter in the X-axis and Y-axis directions are the sizes of the first and second crown-shaped shells 120a and b (radius R, a, height h, etc.). However, if the relationship between the moving distance and the tilt angle is stored in a memory or the like in advance, the distance from the irradiation position 610 in the initial state to the center can be calculated, and the distance from the nanowire emitter 110 to the fluorescent screen can be set. The irradiation position of the electron beam can be automatically adjusted by computer control or the like.

In FIGS. 6 and 7, the moving distance is on the order of millimeters, but it goes without saying that more accurate control is possible on the order of micrometers.

Although the method of adjusting the irradiation position of the electron beam with high accuracy using the strings 510a to 510d has been described with reference to FIGS. 6 and 7, the second crown-shaped shell is also used when the electron guns 100 and 400 are used. Similarly, if the 120b is shifted by any means such as a support rod, the adjustment can be made.

Since the electron guns 100, 400, and 500 of the present invention adjust the delicate irradiation position of the electron beam under vacuum, the surface of the nanowire emitter 110 can be kept clean and the electron beam can be focused with high efficiency. Such electron guns 100, 400, and 500 are adopted in any electronic device having an electron focusing ability. For example, such an electronic device is selected from the group consisting of a scanning electron microscope, a transmission electron microscope, a scanning transmission electron microscope, an Auger electron spectroscope, an electron energy loss spectroscope, and an energy dispersion electron spectroscope. To.

Next, the present invention will be described in detail with reference to specific examples, but it should be noted that the present invention is not limited to these examples.

[Example 1]
The electron gun 500 shown in FIG. 5 was manufactured, and the irradiation position of the electron beam was adjusted. A lanthanum hexaboride (LaB ₆ ) was used as the nanowire emitter 110. LaB ₆ was produced, for example, by the CVD method disclosed in JP-A-2008-262794.

The resulting composition was analyzed by energy dispersive X-ray spectrometer (EDS) for the nanowire, it was confirmed that the nanowire LaB _6. Further, from the HTREM image and the selected area diffraction pattern by the transmission electron microscope, _{the nanowires of LaB 6} are all single crystals, and _{the longitudinal direction of LaB 6} coincides with the crystal direction of <100>, and the end portion thereof. Confirmed that it had {100} planes, {110} planes, and {111} planes. The LaB ₆ nanowires had a diameter of 10 nm to 200 nm and a length of 1 μm to 30 μm. _{Hereinafter, LaB 6} nanowires having a diameter of about 100 nm and a length of 115 μm were used.

The first and second crown-shaped shells 120a and 120b are stainless steel crown-shaped shells having a radius R of 12 mm, a lower surface radius a of 11 mm, and a height h of 8 mm. A shell was used. Graphite spray was used as a lubricant between the first crown-shaped shell 120a and the second crown-shaped shell 120b. The second spherical shell 120b was provided with four strings 510a to 510d.

The first and second crown-shaped shells 120a and 120b were attached to the stage 130, and the nanowire emitter 110 was installed on the concave side. Further, the stage 130 is held by the housing 150 via the telescopic portion 140 which is a bellows made of stainless steel. Here, the concave side of the second crown-shaped shell 120b held in the housing 150 is ^{exposed to a vacuum (vacuum degree: 10-8} Pa), and the first and second crown-shaped shells held in the housing The convex sides of the shells 120a and 120b were exposed to the atmosphere. At this time, the expansion / contraction portion 140 maintained the compression force between the first crown-shaped shell 120a and the second crown-shaped shell 120b at 5N.

The electrode 160 of the electron gun thus obtained was connected to the extraction power source and the acceleration power source, the irradiation position of the electron beam was examined, and adjustment was performed. Specifically, a lead-out voltage of 350 V is applied, then the polarity of the lead-out electrode is reversed, an acceleration voltage of 350 V is applied, and an electron beam is applied to a fluorescent plate (distance between the nanowire emitter 110 and the fluorescent plate: 30 mm) to emit light. Was recorded. The results are shown in FIG. All subsequent operations were performed without breaking the vacuum.

Further, the inclination angles of the nanowire emitter 110 of the electron beam in the X-axis direction and the Y-axis direction and the moving distance of the irradiation position when the four strings 510a to 510d were shifted were investigated. The results are shown in Tables 1 and 2.

FIG. 8 is a diagram showing an irradiation position of an electron beam using the electron gun of the first embodiment.

Although shown in gray scale in FIG. 8, the brightly shown area is the irradiation position of the electron beam, the intersection of the dotted lines represents the center, the dotted line in the horizontal direction is the X-axis, and the dotted line in the vertical direction is Y. Corresponds to the axis. As shown in FIG. 8 (A), the electron beam from the electron gun of Example 1 was irradiated at a position deviated from the center of the fluorescent screen in the initial state.

When the strings 510a to 510d of the electron gun of Example 1 were moved as shown in Tables 1 and 2, the nanowire emitter 110 was tilted by -5 ° to 5 ° in the X-axis direction and -2.6 mm to 2 It was found that it could move by 0.6 mm, tilt by -5 ° to 5 ° in the Y-axis direction, and move by -2.6 mm to 2.6 mm.

From the information on the irradiation position in the initial state of FIG. 8A, the irradiation position of the electron beam is moved by -2.1 mm in the X-axis direction and further by -2.1 mm in the Y-axis direction so that the irradiation position becomes the center. Should be. Therefore, referring to Tables 1 and 2, the strings 510a and 510b were moved by 3 mm and -3 mm, respectively, and the strings 510c and 510d were moved by 3 mm and -3 mm, respectively.

When the strings 510a and 510b were moved by 3 mm and -3 mm, respectively, the nanowire emitter 110 was tilted by -4 ° in the X-axis direction. As shown in FIG. 8B, the irradiation position of the electron beam at this time was moved by −2.1 mm in the X-axis direction from the irradiation position in the initial state (FIG. 8A).

Further, when the strings 510c and 510d were moved by 3 mm and -3 mm, respectively, the nanowire emitter 110 was tilted by -4 ° in the Y-axis direction. As shown in FIG. 8C, the irradiation position of the electron beam at this time moved by −2.1 mm in the Y-axis direction from the irradiation position in FIG. 8B and became the center.

Although not shown, when an electron gun was similarly constructed using a nanowire emitter made of hafnium carbide (HfC) and a nanowire emitter made of carbon nanotubes (single-walled carbon nanotubes, manufactured by Cheap Tube), the vacuum was broken. It was found that the irradiation position of the electron beam can be adjusted.

From the above, it was shown that the electron gun using the nanowire emitter of the present invention can adjust the irradiation position of the electron beam without breaking the vacuum.

By using the electron gun of the present invention, the irradiation position of the electron beam can be adjusted without breaking the vacuum even after the nanowire emitter is set and the inside of the chamber is evacuated. It is used in any device with electron focusing ability such as a microscope, scanning transmission electron microscope, Auger electron spectroscope, electron energy loss spectroscope, and energy dispersion electron spectroscope.

100, 400, 500 Electron gun 110 Nanowire emitter 120a First sphere-shaped shell 120b Second sphere-shaped shell 130 Stage 140 Telescopic part 150 Housing 160 Electrode 410 Lubricant 510a 510b 510c 510d Strings 610, 620, 630, 710, 720 Irradiation position

Claims (14)

A nanowire emitter that emits an electron beam from the end,
A stage including a first coronal shell and a second coronal shell, wherein the first coronal shell is fixed to the stage and the second coronal shell is the stage. It is overlapped so as to slide with respect to the fixed first coronal shell, and the concave side and the convex side of the overlapped first coronal shell and the second coronal shell are respectively. The stage, which is exposed to vacuum and the atmosphere, is attached to the stage so that its ends are on the concave side.
An electron gun comprising a housing that separates the vacuum from the atmosphere and holds the stage via a telescopic portion. The electron according to claim 1, wherein the first crown-shaped shell and the second crown-shaped shell are a part of a sphere having a radius R (where R satisfies 1 mm ≦ R ≦ 1000 mm). gun. The first or second claim, wherein the lower surface of the first crown-shaped shell and the second crown-shaped shell is a circle having a radius a (where a satisfies 1 mm ≦ a ≦ R). Electronic gun. The electron according to any one of claims 1 to 3, wherein the height h from the lower surface to the side surface of the first spherical shell and the second spherical shell satisfies 1 mm ≦ H <2 × R. gun. The electron gun according to any one of claims 1 to 4, wherein the telescopic portion has a bellows shape. The electron gun according to claim 5, wherein the bellows shape is formed of a material selected from the group consisting of a metal material, a rubber-based material, and a thermoplastic elastomer material. Claims 1 to 6 of the telescopic portion maintain a compression force between the first crown-shaped shell and the second crown-shaped shell in a range of 0.1 N or more and 10 N or less under vacuum. The electron gun described in any of. The electron gun according to any one of claims 1 to 7, wherein the stage is attached to the second crown-shaped shell and further includes four strings that control the sliding of the second crown-shaped shell. .. The electron gun according to claim 8, wherein the four strings are evenly spaced in the second coronal shell. The electron gun according to any one of claims 1 to 9, further comprising a lubricant between the first crown-shaped shell and the second crown-shaped shell. The nanowire emitter is _{a needle-like substance selected from the group consisting of lanthanum hexaboride (LaB 6} ), hafnium carbide (HfC), carbon nanotubes, boron nitride nanotubes, and boron nitride nanotubes, claims 1 to 1. The electron gun according to any one of 10. The electron gun according to any one of claims 1 to 11, which is a cold cathode field emission electron gun or a Schottky electron gun. An electronic device comprising the electron gun according to any one of claims 1 to 12. The electronic device is selected from the group consisting of a scanning electron microscope, a transmission electron microscope, a scanning transmission electron microscope, an Auger electron spectroscope, an electron energy loss spectroscope, and an energy dispersion electron spectroscope. 13. The electronic device according to 13.

Images