JPH01161699A - High-speed atomic beam source - Google Patents

Abstract

PURPOSE:To prevent residual ions mixed with a beam from being emitted out of a high-speed atomic beam emitting hole to the outside by impressing a stopping electric field on ions in the space between a cathode and a residual ion stopping electrode. CONSTITUTION:A residual ion stopping electrode 17 in opposition to a plate cathode 11 having a small hole 16 and a magnet impressing a magnetic field 21 about in parallel with a central axis of a cylinder 13 are provided. In a beam 19, redidual ions failed to become high-speed atoms are mixed in addition to high-speed atoms. In the space between the cathode 11 and the residual ion stopping electrode 17, a stopping electric field is impressed on the ions so that the residual ions mixed with the beam 19 gradually loose their energy, and when they reach the residual ion stopping electrode 17, their speed becomes almost zero. Thereby, they can not be emitted from a high-speed atom emitting hole 18 so that only the high-speed atoms 20 in the beam 19 come to be emitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an efficient and compact fast atomic beam source.

[Conventional technology]

Atoms in thermal motion in the atmosphere at room temperature have a kinetic energy of approximately 0.05V. In comparison, atoms that fly warmly and with a large amount of kinetic energy are called "fast atoms," and when they flow in a beam in one direction, they are called "fast atomic beams."

Figure 3 is an explanatory diagram showing an example of a conventionally announced fast atomic beam source.Among the fast atomic beam sources that generate fast atomic beams of gaseous atoms, argon atoms with a kinetic energy of 0.5 to 10 keV are emitted. This figure shows an example of a fast atomic beam source. In Fig. 3, 1 is a cylindrical cathode, 2 is a donut-shaped anode, 3 is a 0.5-10 kV DC high-voltage power supply, and 4 is a cylindrical cathode.
is a gas introduction hole, 5 is an argon gas schematically shown, and 6 is a gas introduction hole.
7 is a plasma, 7 is a high-speed atomic beam emission hole, and 8 is a schematically shown high-speed atomic beam.

Next, the operation of the fast atomic beam source having the above configuration will be explained.

Components other than DC high voltage power supply 3 are placed in a vacuum container (not shown)
After the cylindrical cathode 1 is fully evacuated, argon gas 5 is injected into the cylindrical cathode 1 through the gas introduction hole 4. The cylindrical cathode 1 is grounded. Here, a DC high voltage is applied by the DC high voltage power supply 3 so that the anode 2 has a positive potential and the cathode 1 has a negative potential.This causes a glow discharge between the cathode 1 and the anode 2, and plasma 6 is generated. Then, argon ions and electrons are generated. Furthermore, in this discharge, the electrons emitted from the bottom surface of the cylindrical cathode 1 are accelerated toward the anode 2, pass through the central hole of the anode 2, reach the opposite bottom surface of the cylindrical cathode 1, and the electrons are accelerated here. loses and reverses, and again anode 2
begins to accelerate toward In this way, the electrons oscillate at high frequency between the two bottom surfaces of the cylindrical cathode 1 through the central hole of the anode 2, during which they collide with the argon gas and produce a large number of argon ions. The argon ions thus generated are accelerated toward the bottom of the cylindrical cathode 1 and acquire sufficient kinetic energy. This kinetic energy has a value of about 1 keV when the discharge sustaining voltage between the anode 2 and cathode 1 is, for example, 1 kV. The space near the bottom of the cylindrical cathode 1 is a turning point for high-frequency oscillating electrons, and is a space where a large number of blood energy electrons exist. Argon ions that enter this space recombine with electrons and return to argon atoms. Also, in the argon ion, the cylindrical cathode 1
Some of them come into contact with argon atoms remaining in the space near the bottom of the surface, exchange charges, and return to argon atoms. In a collision between an ion and an electron, the mass of the electron is negligibly small compared to the argon ion, so the kinetic energy of the argon ion is transferred to the atom with almost no loss, resulting in a high-speed atom. Also, in charge exchange between argon ions and argon atoms, no large energy loss occurs, and the kinetic energy of the argon ions is transferred to the atoms as they are, resulting in high-speed atoms.

Therefore, the kinetic energy of the fast atom in this case is 1
It is about keV. These high-speed atoms are emitted as a high-speed atomic beam 8 from an emission hole 7 formed in one bottom surface of the cylindrical cathode 1.

[Problem that the invention seeks to solve]

The high-speed atomic beam 8 emitted from the emission hole 7 contains ions that have failed to become high-speed atoms.

Such ions are called residual ions. In order to remove residual ions and obtain a pure fast atomic beam 8, in a conventional fast atomic beam source, a deflector is installed behind the emission hole 7.
A high voltage is applied to this to remove residual ions, which increases the size of the device and requires an extra high-voltage power source for the deflector.

The present invention has been made in view of these points, and its purpose is to provide a compact fast atomic beam source that efficiently emits fast atomic beams having any energy ranging from low energy to high energy. This is what we provide.

[Means for solving problems]

In order to achieve this purpose, the fast atomic beam source according to the present invention has a flat plate anode installed at the top bottom of the cylinder and a small hole in the center for emitting fast atomic beams, which is maintained at a negative high voltage. A flat plate cathode is installed at the bottom of the cylinder facing the flat plate anode, and is kept at the same potential as the flat plate anode or at a higher potential than the flat plate anode, and has a small hole in the center for emitting high-speed atomic beams and facing the flat plate cathode. The cylinder is provided with a residual ion blocking electrode installed at the center of the cylinder, and a field means for applying a magnetic field approximately parallel to the central axis of the cylinder.

[Effect]

In the fast atom vA source according to the present invention, a blocking electric field is applied to ions in the space between the cathode and the residual ion blocking electrode, and the residual ions mixed in the beam are released from the fast atom beam emission hole. Not released.

〔Example〕

First, the features of the present invention and the differences from the prior art will be described. In the conventional fast atomic beam source, a ring-shaped anode is inserted between two opposing cathodes, whereas in the fast atomic beam source according to the present invention, one cathode and one anode are placed opposite each other. I'm just letting it happen. Therefore, the fast atomic beam source according to the present invention has a simple configuration. Furthermore, in the conventional fast atomic beam source, a deflector is required to remove residual ions, but in the fast atomic beam source according to the present invention, a blocking electric field for ions is created between the cathode having an emission hole and the residual ion blocking electrode. Due to the presence of the deflector, residual ions can be removed even without the deflector, and the device can be made smaller due to the absence of the deflector. Furthermore, since a power source for driving the deflector is not required, economical efficiency is also improved.

FIG. 1 is an explanatory diagram showing an embodiment of a fast atomic beam source according to the present invention. In FIG. 1, 11 is a cathode of a disk flat plate installed at the bottom, 12 is an anode of a disk flat plate installed at the top, 13 is a ceramic or glass cylinder, and 14
15 is a gas introduction hole, 15 is a negative DC high voltage power supply, 16 is a small hole for beam emission, 17 is a residual ion blocking electrode, 18 is a fast atom beam emission hole, 19 is a fast atom schematically shown, 20
is a schematically shown high-speed atomic beam, and 21 is a schematically shown magnetic field.

Next, the operation of the device configured in this way will be explained. Components other than the DC high voltage power supply 15 are placed in a vacuum container and sufficiently evacuated. A negative DC high voltage is applied to the cathode 11 by a DC high voltage power supply 15 . Gas introduction hole 14
For example, oxygen gas is injected into the glass cylinder 13. Oxygen gas is injected so that the pressure inside the glass cylinder 13 is sufficiently higher than the outside.For example, the pressure inside the glass cylinder 13 is 10-'Torr, and the pressure outside the glass cylinder 13 is Let be 10-”Tor r.

Now, a glow discharge is generated between the anode 12 and the cathode 11 inside the glass cylinder 13 by the DC high voltage power supply 15.
Large amounts of oxygen ions are produced. The ions are accelerated toward the cathode 11, and when they reach the vicinity of the cathode 11, they have acquired sufficient kinetic energy. The ions that have obtained sufficient kinetic energy contact the oxygen gas floating around the cathode 11, lose their charge, and return to neutral oxygen atoms. Since the contact between the ions and the oxygen gas is not violent enough to change the kinetic energy, the kinetic energy of the ions is transferred to the neutral atoms, generating high-speed oxygen atoms, which become the beam 19. The ions are emitted from the beam emission hole 16 toward the residual ion blocking electrode 17. The potential of the residual ion blocking electrode 17 is maintained at the same potential as that of the anode 12. In addition to high-speed atoms, the beam 19 contains ions that have failed to become high-speed atoms (residual ions). Since a blocking electric field is applied to ions in the space between the cathode 11 and the residual ion blocking electrode 17, the residual ions mixed in the beam 19 gradually lose energy and reach the residual ion bipositive electrode 17. When this occurs, the velocity becomes almost zero, and the high-speed atoms cannot be emitted outside from the high-speed atom beam emission hole 18, and only the high-speed atoms in the beam 19 are emitted.

This is the high-speed atomic beam 20.

A magnetic field -21 is applied almost parallel to the central axis of the glass cylinder 13 by a magnet (not shown) as a field means installed outside the vacuum container, and a glow discharge occurs inside the glass cylinder 13. improves the generation efficiency of high-speed atoms 20
It has the effect of increasing the amount of emitted. Also, this magnetic field 2
When 1 is applied, it is possible to start the discharge at a lower gas pressure than when this is not applied, which can greatly improve the efficiency of ion generation in the vacuum container, and as a result, a large amount of ions are generated. High-speed atomic beams can be obtained.

Note that if the gas introduced through the gas introduction hole 14 is argon, a high-speed atomic beam of argon is emitted.

Further, the amount of NIA of the fast atomic beam 20 to be emitted can be adjusted by the gas pressure inside the glass cylinder 13 and the strength of the magnetic field 210. The kinetic energy of the fast atomic beam 20 can be set to a predetermined value by adjusting the voltage of the DC high voltage power supply 15.

FIG. 2 is an explanatory diagram showing a second embodiment of the present invention, and is an example in which the potential of the residual ion blocking electrode 17 is kept higher than the potential of the anode 12 by the DC power supply 22. In this figure, the same or corresponding parts as in FIG. 1 are given the same reference numerals. The operation of this second embodiment is similar to that of the first embodiment shown in FIG. can be done completely.

In the above embodiment, the cathode 11 and the anode 12 are disk-shaped, and the tube 13 is cylindrical.
1. The same effect can be obtained even if the anode 12 has a shape other than a disk or cylinder, such as a square plate and a tube 13 having a square cross section.

When high-speed ions or atoms collide with a solid, sputtering occurs on the solid surface and secondary electrons, secondary ions, and light are emitted. It is well known that these phenomena are used for processing and analysis. However, if the solid is an insulator, it becomes charged due to the collision of ions, blocking the incidence of subsequent ions and hindering processing and analysis, whereas such a phenomenon occurs with electrically neutral atoms. There is a notable difference in that processing and analysis can be performed without any delays. In this sense, the small fast atomic beam source of the present invention is very effective.Also, conventional fast atomic beam sources were equipped with a deflector to remove residual ions and obtain pure fast atomic beams, but this Since the fast atomic beam source according to the invention does not require a deflector, it can be further miniaturized, and at the same time, it does not require a power source to drive the deflector, improving economic efficiency.

〔Effect of the invention〕

As explained above, in the present invention, by installing the residual ion blocking electrode opposite to the flat plate cathode, the deflector that was conventionally necessary to prevent the release of residual ions to the outside is unnecessary, so the device can be made compact. It has the effect of

In addition, by providing a field means that applies a magnetic field almost parallel to the central axis of the ceramic or glass cylinder, it is possible to improve the efficiency of generating glow discharge inside the cylinder, and release high-speed atoms. Since the amount can be increased,
This has the effect of increasing the efficiency of the device.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing a second embodiment of the invention, and FIG. 3 is an explanatory diagram showing a conventional device. 11...Cathode, 12...Anode, 13...Cylinder, 1
4...Gas introduction hole, 15...DC high voltage power supply, 16.
...Small hole, 17...Residual ion blocking electrode, 18...
High speed atomic beam emission hole, 19... High speed atom, 20... High speed atomic beam, 21... Magnetic field.

Claims (1)

[Claims] A flat plate anode installed at the top bottom of the cylinder, and a flat plate cathode that is maintained at a negative high voltage and has a small hole in the center for emitting high-speed atomic beams, and placed opposite to the flat plate anode at the bottom bottom of the cylinder. a residual ion blocking electrode which is kept at the same potential as the flat anode or at a higher potential than the flat anode and has a small hole in the center for emitting high-speed atomic beams and is placed opposite the flat cathode; A high-speed atomic beam source comprising: field means for applying a magnetic field substantially parallel to a central axis.