JPS63143800A - High speed atomic beam source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radiation source that emits a high-speed atomic beam with high extraction efficiency.

[Prior art] Among the high-speed atomic beam sources that generate high-speed atomic beams of gaseous atoms, which have been previously published with reference to Figure 3, kinetic energy is 0.
．． An example of a fast atomic beam source that emits 5 to 10 keV argon atoms will be described.

In the figure, 1 is a cylindrical cathode having both end faces, and 2 is a ring-shaped anode. Both end surfaces of the cathode 1 are made of thin metal plates. 3 is a 0.5-10kV DC high voltage power supply, 4 is a negative g!
1 is a gas introduction hole attached to one end face of cathode 1; 5 is argon gas; 6 is plasma; 7 is a fast atomic beam emission hole bored in the other end face of cathode 1; 8 is a fast atomic beam.

Of the above components, except for the DC high voltage power supply 3, are placed in a vacuum container (not shown). After the air in the vacuum container is sufficiently exhausted, argon gas 5 is introduced into the cylindrical cathode 1 through the gas introduction hole 4. A DC high voltage is applied from a DC high voltage power supply 3 so that the anode 2 has a positive potential and the cathode 1 has a negative potential. By this application, glow discharge occurs between both end faces of the negative 8i1 and the anode 2 located between them, plasma 6 is generated, and argon ions and electrons are generated.

In these discharges, electrons emitted from the end face on the side having the high-speed atomic beam emission hole 7 are accelerated toward the anode 2, gain sufficient kinetic energy, collide with argon gas molecules, and ionize the argon gas. .

Furthermore, the electrons that have reached the anode 2 pass through the hole in the center of the anode 2 and begin to be decelerated toward the end face of the cathode 1 on the side where the gas introduction hole 4 is attached, and the electrons that have reached the vicinity of this end face are It loses speed, reverses, and begins to accelerate toward the anode 2 again.

As described above, electrons vibrate at high frequency between the opposite end surfaces of the cathode 1 with the anode 2 as the center, and in this process, a large number of argon ions are generated.

Further, the space near both ends of the cathode 1 is a turning point of high-frequency oscillating electrons, and is therefore a space in which a large number of low-speed electrons exist. Further, this space is also a space in which a large number of low-speed secondary electrons emitted by ions colliding with the vessel walls on both end faces of the cathode 2 exist.

Argon ions generated by the collision between electrons and argon gas molecules are accelerated toward both end faces of the cathode 1,
Argon enters the space near both end faces and recombines with the many slow electrons there, creating high-speed argon atoms.

When an ion and an electron collide, the kinetic energy of the ion is not lost because the mass of the electron is negligible compared to that of the ion, and the kinetic energy of the fast atom becomes comparable to that of the ion. .

The fast atoms formed in this process are ejected from the fast atom beam 8 through the fast atom beam emission hole 7 drilled in one end face of the cathode 1.
and is released. For example, if the DC high voltage power supply 3 is 1k
If the voltage is set to V, the accelerated ions will reach the vicinity of both end faces of the cathode 1, and since these ions have a kinetic energy of about 1 keV, the kinetic energy of the fast atomic beam 8 will also be about 1 keV.
keV.

[Problem to be Solved by the Invention 1] In the conventional high-speed atomic beam source as described above, the end face of the cathode, which emits electrons necessary for generating ions from atoms, is composed of a flat plate. For this reason, the plasma spreads throughout the interior of the cylindrical cathode, making it difficult to generate high-density plasma. Therefore, it is not easy to extract a high-power, high-speed atomic beam.

Furthermore, the cathode end face with fast atomic beam emission holes is usually
Because it is made of a thin metal plate, the beam that receives the bombardment of high-speed atoms and ions is spattered and consumed, which poses a problem in extracting high-speed atomic beams over a long period of time.

An object of the present invention is to solve the above-mentioned problems and provide a high-speed atomic beam source that can extract high-power high-speed atomic beams over a long period of time and has good extraction efficiency.

[Means for Solving the Problems] In order to achieve the above object, the fast atomic beam source of the present invention includes a first cathode composed of a plurality of hollow cathodes, and a first cathode having a honeycomb structure. A second cathode facing each other with substantially the same central axis, an anode disposed between the first and second cathodes and having an opening approximately in the center, and a direct current connected between the anode and the cathode. It is characterized by being equipped with a high voltage power supply.

[Function] In the present invention, plasma density is increased by configuring one cathode with a plurality of hollow cathodes. Further, by forming the other cathode which also serves as a fast atom emission hole into a honeycomb structure, it is possible to prevent the fast atom emission hole from being consumed by sputtering.

[Example] The present invention will be described in detail with reference to FIG.

In the figure, 3 is a DC high-voltage power supply, and 8 is a high-speed atomic beam. Reference numeral 21 denotes a cathode constructed by assembling a plurality of hollow cylindrical hollow cathodes made of a heat-resistant material such as stainless steel. 22 is a honeycomb-structured cathode having a high-speed atomic beam emission hole, and 23 is an anode. These operations are as follows.

Components other than DC high voltage power supply 3 are placed in a vacuum container (not shown)
After evacuating sufficiently, e.g. argon gas,
The introduction is continued until the degree of vacuum within the vacuum container reaches 10-2 to 10-5 Torr. Then, the anode 23 is at a positive potential and the cathode 2 is at a positive potential.
A high DC voltage is applied by the DC high voltage power source 3 for discharge so that 1 and 22 have a negative potential. The cathodes 21 and 22 are short-circuited so that they have the same potential.

By applying this high voltage, glow discharge occurs between the cathode 21 and the anode 23 and between the cathode 22 and the anode 23, generating plasma and generating argon ions and electrons.

Hereinafter, as in the case of the conventional example, the electrons emitted from the cathode 21 are accelerated toward the anode 23, pass through the central opening of the anode 23, reach the cathode 22, where they lose speed and reverse. , it begins to accelerate again toward positive Vi23. On the inner surface of each hollow cathode constituting the cathode 21,
Many electrons are incident obliquely, so each hollow cathode emits many secondary electrons. As a result, the discharge current increases, the cathode 21 becomes red hot, and also emits thermoelectrons.

The electrons generated in large quantities in this way oscillate at high frequency between the cathodes 21 and 22 through the central opening of the anode 23,
This process generates a large number of argon ions. The generated argon ions are accelerated toward the cathode 22 and acquire sufficient kinetic energy. This kinetic energy has a value of about 1 keV when the discharge sustaining voltage between the anode 23 and the cathode 22 is, for example, 1 kV.

Further, the space near both ends of the cathode 1 is a turning point of high-frequency oscillating electrons, and is therefore a space in which a large number of low-speed electrons exist.

The pulbon ions that have entered this space collide with slow electrons and recombine to become argon atoms.

When an ion and an electron collide, the mass of the electron is negligible compared to that of the ion, so the kinetic energy of the ion is not lost, and the kinetic energy of the fast atom becomes comparable to that of the ion.

Therefore, the kinetic energy of the ions is directly transferred to the atoms and is emitted as a high-speed atomic beam 8.

In the present invention, by using a plurality of hollow cathodes, the plasma density is increased and a large amount of ions are generated. The high-speed atomic beam emission hole, which also serves as a cathode, has a honeycomb structure to maintain a high aperture ratio. These 2
For two reasons, it is possible to emit a high-power high-speed atomic beam, and the fast-atomic beam emission hole is prevented from being consumed by sputtering.

In the above example, the case of an anode with a hole in the center was explained, but if a grid is provided in the hole in the center of the anode as shown in Fig. 2, the electrons emitted from one cathode will not be directed toward the periphery of the anode. can be directed to the other electrode through the central part, resulting in even greater effects.

[Effects of the Invention] As explained above, in the present invention, since a cathode composed of a plurality of hollow cathodes is used, plasma generation efficiency is high and high-speed atomic beams can be extracted more efficiently than conventional radiation sources. be able to.

Since the high-speed atomic beam emission hole, which also serves as a cathode, has a honeycomb structure, the aperture ratio is high, and therefore it is possible to prevent the emission hole from being consumed by sputtering.

Furthermore, like high-speed ion beams, high-speed atomic beams can be used for thin film formation by sputter deposition, fine pattern processing by sputter etching, and material evaluation by secondary ion mass spectrometry.

Furthermore, since high-speed atomic beams are uncharged, they are effective not only for processing metals and semiconductors, but also for processing insulating materials such as plastics and ceramics for which processing 2 analysis using the ion beam method cannot be applied. 1. This is extremely useful for improving the efficiency of analysis, etc.

perspective view, FIG. 3 is a perspective view showing a conventional fast atomic beam source.

3...DC high voltage power supply, 8...High-speed atomic beam, 21.22... cathode, 23... Anode.

Claims (1)

[Scope of Claims] A first cathode composed of a plurality of hollow cathodes; a second cathode having a honeycomb structure and facing the first cathode with substantially the same central axis; A fast atomic beam source comprising: an anode disposed between two cathodes and having an opening approximately in the center; and a DC high voltage power supply connected between the anode and the cathode.