JP3067248B2 - Ion source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to surface modification, surface treatment,
The present invention relates to an ion source used for a thin film forming apparatus and the like.

[0002]

2. Description of the Related Art When an ion beam is applied to a workpiece, the floating energy of the ion beam changes into thermal energy,
Since melting and evaporation occur on the surface of the workpiece, it is used for processing the workpiece such as induction, polishing, etching, and surface treatment. In recent years, it has been used to manufacture IC circuits, implant impurities into semiconductors, and oxidize. It is used for surface treatment such as formation of a film or a nitride film, and when forming a thin film.

[0003] An ion source is known as an apparatus for obtaining this ion beam. The ion source is configured to generate plasma in a plasma generation chamber, take out only ions out of the plasma, and accelerate it at a high pressure to form an ion beam. There are an ion source dedicated to gas ions and an ion source of a type in which a substance such as metal in a crucible is vaporized and turned into plasma in a plasma generation chamber.

[0004]

By the way, in the conventional high current metal ion source, in order to evaporate a substance and extract an ion beam, if the substance to be evaporated is a high melting point metal such as tungsten, for example, the evaporating section is formed. The temperature must be raised to several thousand degrees, and it is virtually impossible to extract an ion beam of a high melting point metal.

For this reason, a bucket type ion source having a function of extracting atoms generated by the sputtering action as an ion beam has been proposed, and a substance for which an ion beam is to be generated is configured as a sputter target, so that the ion source can be several thousand degrees. Since the atoms can be knocked out by the sputtering action without raising the temperature, a high melting point metal ion beam can be obtained. However, secondary electrons generated during sputtering are accelerated by the potential between the sputter target and the plasma, and are incident as a high-energy electron beam on a beam extraction electrode (plasma grit) on a surface facing the sputter target and the like, and the thermal load thereof is increased. Therefore, there is a problem that the plasma grit is deformed or damaged. Therefore, the present invention has been made in view of such circumstances, and an object of the present invention is to provide an ion source capable of preventing a beam extraction electrode (plasma grit) from being deformed or damaged by electrons. It is in.

[0006]

In order to achieve the above object, an ion source of the present invention is formed in a chamber serving as an anode.
Elongation for plasma confinement around the outer periphery of the plasma chamber
A magnet is arranged, a beam extraction electrode is provided in front of the plasma chamber to extract plasma-converted atoms as an ion beam, and a working gas is introduced into the chamber behind the plasma chamber.
The working gas introduction part is provided,
Approximately in the center, supported by a disk-shaped sputter target support
A disc-shaped sputtering target is, the beam extraction electrode
And the sputtering target
The sputter target support on the back side of the
Magnets for binding secondary electrons generated during operation with lines of magnetic force are arranged radially so that S poles and N poles alternate.
And a cathode on the front and top and bottom of the sputter target
And a sputter target
This is an ion source to which a negative high voltage is applied .

[0007]

The working gas is turned into plasma and collides with a sputter target to which a negative voltage is applied. As a result, atoms are knocked out of the sputter target, the atoms are turned into plasma in the plasma chamber, and are extracted by the beam extraction electrode to obtain an ion beam. When atoms are knocked out by the collision of the working gas, secondary electrons are generated. However, since these electrons are bound by lines of magnetic force formed by the magnet, the electrons are incident on the beam extraction electrode (plasma grit). Since it is suppressed, it is possible to prevent the plasma grit from being deformed or damaged by electrons.

[0008]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a bucket type ion source of a sputtering system.

As shown in FIG . 1, the ion source 1 of the present invention
Is formed by a filament 2 serving as a cathode for converting a working gas such as Ar into plasma and a chamber 5a serving as an anode 3.
It mainly comprises a plasma chamber 5 formed, a sputter target 4 to which a negative high voltage is applied, and a beam extraction electrode (plasma grid) 6 for extracting atoms of the plasma as an ion beam. This ion source 1
In order to efficiently transport a large-area, large-current ion beam, the plasma grid 6 is formed of electrodes having a geometrically focused shape, and the plasma grid 6 is disposed facing the beam outlet 7. A sputter target 4 is supported and supported by a sputter target support 8 at a substantially central position behind the plasma chamber 5 facing the plasma grid 6. In addition, filament 2
Is provided on the front side of the
You. In the chamber 5a behind the sputter target 4
A working gas introduction unit 9 for introducing a working gas is provided. A working gas such as Ar from the working gas introduction unit 9 is turned into plasma by a discharge between the filament 2 and the anode 3 and becomes negative .
The structure collides with the sputter target 4 to which a high voltage is applied. In the illustrated example, a magnet (permanent magnet) in which S poles and N poles are alternately arranged so as to surround the chamber 5a forming the cylindrical plasma chamber 5 as shown in FIGS. ) 10 is the magnet support 1
1, 12 are provided. Specifically, these magnets 10 are arranged such that magnetic lines 13 are formed by their polarities as shown in the figure, and the magnetic lines 13 improve the confinement efficiency of plasma.

FIG . 3 is a perspective view of the ion source 1 shown in FIG.
Between the target 4 and the sputter target support 8
2 shows a cross section of a portion. Now, as shown in FIG.
In, in the support of the sputter target supporting portion 8 as a back side of the sputter target 4, a magnet (permanent magnet) 14 such that the radial and S and N poles, as shown in FIGS. 1 to 3 will alternately Have been placed. Specifically, the magnets (permanent magnets) 14 are the magnetic field lines 15 in the vicinity of the target 4 surface, as shown in FIG. 1 by the polarity of the magnets 14 are formed, in this magnetic field lines 15, generated from a sputter target 4 during sputtering action The secondary electrons are arranged to bind the secondary electrons. In order to cool the sputter target 4 , a water partition plate is fixed between the magnets by spot welding or the like, and cooling water flows between the magnets.

Next, the operation of this embodiment will be described.

When a working gas such as Ar is introduced into the plasma chamber 5 from the working gas inlet 9, the working gas is turned into plasma by a discharge between the filament 2 and the anode 3, and this is turned into a sputter target to which a negative voltage is applied. Collision 4 Due to this sputtering action , atoms of the constituent material are knocked out of the sputtering target 4 and turned into plasma (ionization) in the plasma chamber 5. Only the positive ions of these atoms are converged by the beam extraction electrode (plasma grid) 6 and further accelerated to be extracted from the beam extraction port 7 as a large-area, large-current ion beam.

Thus, by forming a substance for which an ion beam is to be generated (for example, a refractory metal such as tungsten) as the sputter target 4, a direct current and a high current ion beam of the refractory metal can be obtained.

At the time of sputtering operation, that is,
Working gas such as Ar collides with the sputter target 4
And atoms of the constituent material of the sputter target 4 strike
At the same time, the secondary
Electrons are emitted. The secondary electrons are
This will affect the plasma conversion efficiency. Furthermore, this 2
Secondary electrons are applied at the potential between the sputter target and the plasma.
To a high-energy electron beam
To the pole (plasma grid) 6 and
Damage and deformation of the beam extraction electrode (plasma grid) 6
And so on. In the present invention,
Target support part on the back side of target 4
8, the secondary electrons generated during the sputtering action are bundled by the lines of magnetic force.
The magnets 14 for binding are formed radially and the S pole and the N pole are
Since they are arranged alternately, the secondary electrons
Spiral movement wrapping around the magnetic field line 15 by the magnet 14
And secondary electrons can be reliably bound.

As a result, the plasma of the ejected atoms
Without affecting the conversion efficiency.
It is also possible to prevent breakage and deformation of the rasma grid 6.

[0017] In the present invention, the secondary electrons, magnetic
Make a spiral motion that wraps around the magnetic field line 15 due to the stone 14
During collision with neutral particles in the plasma chamber 5
As a result, plasma generation on the front surface of the sputter target 4 is promoted, and high-density plasma is formed there. As a result, the sputter efficiency at which atoms are knocked out of the sputter target 4 is improved, and it becomes possible to extract a larger number of metal ion beams than before. Further, in the present invention, the disc-shaped
The sputter target 4 is placed against the beam extraction electrode 6.
So as to face away from the sputter target 4.
The atoms of the constituent material are efficiently converted into plasma
The light enters the chamber 5 and is generated by the high-density plasma in the plasma chamber 5.
Into plasma and become positive ion atoms.
It is extracted from the pole 6 as an ion beam. In other words, the book
The ion source of the invention is a large-area, large-current, high-melting-point metal ion source.
Beam is easily obtained.

[0018]

In summary, according to the present invention, electrons generated when atoms are hit from a sputter target are bound by lines of magnetic force formed by a magnet. It has an excellent effect that it can be prevented.

Further, by binding high-energy electrons to the front surface of the sputter target, the generation efficiency of the metal ion beam can be improved as compared with the prior art.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example in which a magnet is arranged on the back side of a sputter target.

FIG. 3 is a view taken in the direction of arrows AA in FIG. 2;

[Explanation of symbols]

 4 Sputter target 5 Plasma chamber 6 Beam extraction electrode 14 Magnet 15 Line of magnetic force

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 27/00-27/26 H01J 37/08

Claims (1)

(57) [Claims] 1. A plug formed in a chamber serving as an anode.
Permanent magnet for plasma confinement
And location, in front of the plasma chamber is provided with a beam extraction electrode withdrawing the plasma and atoms as an ion beam, the flop
Working gas that introduces working gas into the chamber behind the plasma chamber
An introduction section is provided, and further, approximately in the center behind the plasma chamber.
The circle supported by the disk-shaped sputter target support
The disk-shaped sputter target is moved to the beam extraction electrode.
It is provided so as to face, and the back side of the sputter target
In the sputter target support part
The magnets for binding the generated secondary electrons with the lines of magnetic force are radiated.
And arranged so that the S pole and the N pole are alternated.
The front and upper and lower positions of the cathode
And a high negative voltage on the sputter target.
An ion source characterized in that a pressure is applied .