JP2666143B2 - Ion neutralizer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ion neutralizer applied to the generation of a wide range of fast atomic beams from low energy to high energy.

[Conventional technology]

FIG. 2 is a schematic configuration diagram showing an example of this type of ion neutralizer. In the figure, 1 is a cylindrical envelope having a thick central portion, 2 is a circular filament for emitting thermoelectrons,
Reference numeral 3 denotes an ion beam, 4 denotes a high-speed electron beam, 5 denotes a power supply for heating the filament 2, and 6 denotes a DC bias power supply. The filament 2 is stretched around the central axis of the envelope 1 and is housed in a thick central portion of the envelope 1, and the components other than the power supplies 5 and 6 are housed in a vacuum container. ing.

In such a configuration, the circular filament 2 is heated by the power source 5 to emit a large amount of thermoelectrons. The envelope 1 is biased by a DC power supply 6 to a potential several volts lower than the filament 2. Accordingly, the thermoelectrons emitted from the filament 2 are repelled by the wall of the envelope 1 and concentrated near the central axis of the envelope 1, forming a high-density electron cloud there. When the ion beam 3 is incident on the electron cloud, ion-electron collision and recombination occur, and the ion beam 3 is converted into a fast atomic beam 4. In ion-electron collision at the time of electron recombination, the mass of the electron is much smaller than that of the ion.
Is born.

[Problems to be solved by the invention]

However, in this ion neutralizer, when the kinetic energy of incident ions is low because the output voltage of the heating power supply 5 is applied to both ends of the filament 2, the ions are affected by this electric field ( There are the following problems: 1) the ion trajectory is bent and the generation efficiency of high-speed atoms is reduced; and 2) the convergence condition of ions is broken, so that a convergent high-speed atomic beam cannot be obtained.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to employ electron impact indirect heating of a refractory metal sleeve as a method of forming a thermoelectron cloud. An object of the present invention is to provide an ion neutralizer capable of efficiently generating a high-speed atomic beam even for ions having low energy.

[Means for solving the problem]

The ion neutralizer according to the present invention includes a refractory metal sleeve that internally generates an electron cloud for neutralizing the charge of ions by thermionic emission, and a heating thermoelectron of a sleeve wound around the outer periphery of the sleeve. From a filament that generates heat, a power supply that heats the filament, and a DC high-voltage power supply that is connected between the sleeve and the filament for heating the thermoelectrons for heating generated from the filament by an electric field and heating the sleeve by impact. Be composed.

[Action]

In the present invention, since high-melting-point metal sleeve adopts electron-impact indirect heating, no harmful electric field is generated for ions in the electron cloud, and high-speed atomic atoms are efficiently applied to low-energy ions. A beam is generated and converted to a high-speed atomic beam without breaking the convergence condition for a low-energy convergent ion beam.

〔Example〕

FIG. 1 is a partially cutaway configuration view showing an embodiment of an ion neutralizer according to the present invention, and the same parts as those in the above-mentioned figures are denoted by the same reference numerals. In the figure, 21 is a high melting point metal sleeve for generating thermoelectrons, 22 is an envelope, 23 is a filament, 24
Is a DC power supply for electron acceleration, and components other than the power supplies 5 and 24 are housed in a vacuum vessel.

In such a configuration, the filament 23 is heated by the power source 5 to generate a large amount of thermoelectrons. The refractory metal sleeve 21 for emitting thermoelectrons is maintained at a potential several hundred volts higher than the filament 23 and the envelope 22 by a DC power supply 24. Therefore, the thermoelectrons generated from the filament 23 are accelerated by the high potential and impact the sleeve 21 to heat it to a high temperature. Sleeve 21 heated to high temperature
A large amount of thermoelectrons are emitted from the wall surface of, and a high-density electron cloud is formed inside the sleeve. When the ion beam 3 is incident on the electron cloud, ion-electron collision and recombination occur, and the ion beam 3 is converted into a fast atomic beam 4. In the ion-electron collision at the time of electron recombination, the mass of the electron is much smaller than that of the ion, and the kinetic energy of the ion is hardly lost. If the ion beam 3 is previously focused by an electromagnetic lens, a converged high-speed atomic beam 4 can be obtained.

In the ion neutralizer configured as described above, there is no harmful electric field for ions as in the conventional apparatus in the space where the fast atom beam 4 is generated (the space inside the sleeve 21). Even if a low-energy ion beam is incident, there are problems such as (1) the orbit is deflected and the generation efficiency of fast atoms is reduced, and (2) the convergence condition is broken and the convergence state of fast atom beams is deteriorated. Absent. Thus, the ion neutralizer is applicable to a wide range of fast atom beam generation from low energy to high energy.

〔The invention's effect〕

As described above, according to the present invention, a wide range of converged fast atomic beams from low energy to high energy can be obtained, so that thin film formation by sputter deposition, fine pattern processing by sputter etching, It can be used for material evaluation by secondary ion mass spectrometry. In particular, the fast atomic beam is non-chargeable, and is extremely effective not only for metals and semiconductors but also for insulators such as plastics and ceramics, which are not good at the ion beam method. In particular, fast atomic beams with low energy can be an effective weapon for analyzing and evaluating insulators. In that sense, obtaining an ion neutralizer that generates low-energy, high-speed atoms is extremely effective for improving the efficiency of processing and analysis.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an ion neutralizer according to one embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of a conventional ion neutralizer. 3 ... Ion beam, 4 ... High speed atomic beam, 5 ... Power supply for heating filament, 21 ... High melting point metal sleeve for generating thermoelectrons, 22 ... Envelope, 23 ... Filament, 24 ... Electron DC power supply for acceleration.

Claims (1)

(57) [Claims] 1. An ion neutralizer for neutralizing the charge of an ion by injecting an ion beam into an electron cloud to generate a high-speed atomic beam. A high-melting-point metal sleeve internally generated by the emission, a filament for generating thermoelectrons for heating the sleeve wound around the outer periphery of the sleeve, a power supply for heating the filament, and heating heat generated from the filament An ion neutralizer comprising a DC high-voltage power supply connected between the sleeve and a filament for accelerating electrons by an electric field and heating the sleeve by impact.