JPH06223998A - Contactless plasma form control device - Google Patents

Abstract

PURPOSE:To provide a contactless plasma form control device of a contactless type at a low cost which can be large-sized. CONSTITUTION:A Helmholtz coil 3 comprising a pair of circular coils to form a uniform magnetic field B by supplying a current to the circular coils, and a quadrupole field E are formed around a vacuum container 1 as a passage of plasma 1. Four electrodes 6 to form a thin sheet of the plasma 1 are fixed by EXB drift motion generated at the quadrupole field E.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact plasma shape control device, and is considered to be applicable to general devices using plasma such as a plasma generator for a large area process, a linear ion gun, and a plasma accelerator. In recent years, it is useful when applied to an apparatus, such as an etching or sputtering apparatus, which is required to perform processing efficiently in a short time.

[0002]

2. Description of the Related Art In recent years, in order to efficiently use plasma industrially, the shape of the plasma is changed from a cylindrical shape so that the plasma is uniformly irradiated on a surface or a line, and the thickness of its cross section is reduced to a sheet shape. That is, it is necessary to make a sheet. In addition, there is an increasing demand for efficient sheeting for processing lasers. In addition, there is a need to make plasma into a sheet by using an isotope separator that separates isotopes at high speed by making plasma into a sheet to increase its surface area and a small SOR that accelerates electrons in the sheeted plasma quickly. high.

Due to such a need, a plasma shape control device is used to form plasma into a sheet.

4 and 5 are longitudinal sectional views of a plasma shape control device according to the prior art. Among them, the plasma shape control device shown in FIG. 4 is a contact type plasma shape control device using a metal limiter (hereinafter referred to as a contact plasma control device), and the plasma shape control device shown in FIG. 5 is a coil or a permanent magnet. It is a non-contact type plasma shape control device using a magnet (hereinafter referred to as a non-contact plasma shape control device).

As shown in FIG. 4, the contact plasma shape control device has a vacuum container 2, a Helmholtz coil 3 and a metal limiter 12. Of these, the vacuum container 2
Is a cylindrical vacuum container, which is a passage for the plasma 1 drawn from a plasma source (not shown).

The Helmholtz coils 3 are a pair of circular coils fixed to the outer periphery of the vacuum container 2. The pair of circular coils have the same radius, and are provided in the axial direction of the vacuum container 2 with a distance L equal to the radius.
The Helmholtz coil 3 forms a uniform magnetic field B along the axial direction inside the vacuum container 2 when a current of the same magnitude is applied to each of the circular coils in the same direction.

The metal limiter 12 is a metal disk having a slit 12a in the center thereof, and is fixed inside the vacuum container 2 so that the plasma 1 passes through the slit 12a.

According to the above-mentioned contact plasma shape control device, the plasma 1 is extracted from the plasma source in the direction of arrow 5 by the uniform magnetic field B formed by the Helmholtz coil 3, and is confined inside the vacuum container 2. After that, the plasma 1 flows in the direction of the arrow 5, but is thinned into a sheet when passing through the slit 12a of the metal limiter 12 in the middle.

Next, the non-contact plasma shape controller shown in FIG. 5 has a vacuum container 2, a Helmholtz coil 3 and a coil or permanent magnet 13. Among them, the vacuum container 2 and the Helmholtz coil 3 are the same as the vacuum container 2 and the Helmholtz coil 3 of the contact plasma control device shown in FIG.

The coil or the permanent magnet 13 is used for the vacuum container 2
The cusp magnetic field B is fixed to the outer peripheral part of the
Form ₂ .

According to the above non-contact plasma shape control device, the plasma 1 drawn from the plasma source flows in the vacuum container 2 in the direction of the arrow 5, but passes through the portion where the coil or the permanent magnet 13 is fixed. In doing so, a thin sheet is formed by the cusp magnetic field B ₂ .

[0012]

Among the plasma shape control devices according to the prior art as described above, in the contact plasma shape control device, since the plasma 1 directly contacts the metal limiter 12, the plasma 1 is controlled by the metal limiter 12.
However, there is a problem in that plasma particles are sputtered on the surface of the metal limiter 12 to cause plasma contamination.

In the non-contact plasma shape control device, the plasma 1 can be formed into a sheet in a non-contact manner, but since the cusp magnetic field B ₂ is formed with the increase in size of the device, the coil 13 has a large size of several + A to several hundred A. It is necessary to pass a current, which requires a power source with a large capacity. Permanent magnet 1
In the case of forming the cusp magnetic field B ₂ by 3 as well, a large and strong permanent magnet is required as the device becomes larger. In any case, there is a problem that the cost of the device becomes considerably high.

In view of the above-mentioned prior art, it is an object of the present invention to provide a non-contact type plasma shape control apparatus which is a non-contact type and which can be made large in size at low cost.

[0015]

The present inventors have found that plasma in a magnetic field (E) has an E × B drift velocity due to an electric field (E), and the plasma is deformed in the velocity direction. . The present invention is based on such findings. That is, the structure of the present invention that achieves the above object is fixed to the vacuum container that is the passage of the plasma and the outer peripheral portion of the vacuum container, and forms a uniform magnetic field (B) inside the vacuum container along the axial direction. The Helmholtz coil and the outer periphery of the vacuum container are fixed, and an electric field (E) is formed inside the coil.
And an electrode that causes an E × B drift motion with respect to the plasma.

[0016]

According to the present invention having the above structure, the plasma drawn from the plasma source by the uniform magnetic field (B) formed by the Helmholtz coil flows in the vacuum chamber. The plasma then passes through an electric field (E) formed by the electrodes, whereupon E × B with respect to the plasma.
Drift movement is generated. As a result, the plasma is
It is made into a thin sheet.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. The same parts as those in the conventional technique are designated by the same reference numerals, and duplicate description will be omitted.

FIG. 1 is an explanatory view of a non-contact plasma shape control device according to an embodiment of the present invention. As shown in the figure, the non-contact plasma shape control device according to the embodiment of the present invention includes a vacuum container 2, a Helmholtz coil 3 and four electrodes 6.

Of these, all four electrodes 6 are fixed to the outer peripheral portion of the vacuum container 2. Further, a voltage is applied to each electrode 6 from a power source (not shown) so as to have a predetermined polarity (specifically described later). Thus 4
The individual electrodes 6 form a quadrupole electric field E inside the vacuum container 2.

FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, showing the state of the lines of electric force of the quadrupole electric field E and the direction of the E × B drift motion. Further, FIG. 3 shows the A- of FIG. 1 in which the vacuum container 2 and the Helmholtz coil 3 are omitted.
It is an A line arrow cross section, and is an explanatory view showing the direction of ExB drift motion and the state where plasma 1 was made into a sheet.

As shown in FIG. 2, a voltage is applied to the four electrodes 6 such that the polarities thereof are +, −, +, − in the clockwise order from the upper right of the figure. Therefore, the four electrodes 6 form a quadrupole electric field E having lines of electric force 8 directed from each of the + electrodes to each of the − electrodes. Therefore, as shown in FIG.
In the direction of arrow 9 in the quadrupole electric field E (electric field strength)
/ (B) causes an E × B drift motion having a drift velocity determined by (magnetic field strength), resulting in a thin sheet. The width 11 of the sheet-shaped plasma 1 can be adjusted by the value of the electric field strength.

The size of the device can be increased by enlarging the electrodes and increasing the voltage without passing a current.

According to the above embodiment, the plasma 1 extracted from the plasma source by the uniform magnetic field B is stored in the vacuum chamber 2
Flows in the direction of the arrow 5 inside, and when passing through the quadrupole electric field E formed by the four electrodes 6, an E × B drift motion is generated and a thin sheet is formed.

The vacuum container 2 need not be limited to the cylindrical one as in the above embodiment.

[0025]

As described above in detail with reference to the embodiments, the present invention is a non-contact type in which plasma is formed into a sheet by the electric field E. Therefore, unlike the case where the metal limiter is used, plasma contamination does not occur. In addition, since no current flows between the electrodes, there is no power consumption, and therefore, there is no need for a large-capacity power source as in the case of using a cusp magnetic field. Therefore, it is advantageous in cost as compared with the conventional plasma shape control device, and the size of the device can be increased at low cost.

Further, since there is no other magnetic field such as the cusp magnetic field, there is no disturbance of the uniform magnetic field B, so that the plasma can be efficiently confined.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a non-contact plasma shape control device according to an embodiment of the present invention.

2 is a cross-sectional view taken along the line AA of FIG. 1 and is an explanatory view showing a state of electric lines of force of a quadrupole electric field E and a direction of E × B drift motion.

3 is a cross-sectional view taken along the line AA of FIG. 1 in which a vacuum container 2 and a Helmholtz coil 3 are omitted, and an explanatory view showing a direction of E × B drift motion and a state in which a plasma 1 is formed into a sheet. Is.

FIG. 4 is a vertical cross-sectional view of a contact plasma shape control device according to a conventional technique.

FIG. 5 is a vertical cross-sectional view of a non-contact plasma shape control device according to a conventional technique.

[Explanation of symbols]

 1 plasma 2 vacuum container 3 Helmholtz coil 6 electrode B uniform magnetic field E quadrupole electric field

Claims (1)

[Claims] 1. A vacuum vessel which is a passage of plasma, a Helmholtz coil fixed to the outer peripheral portion of the vacuum vessel and forming a uniform magnetic field (B) along the axial direction inside the vacuum vessel, A non-contact plasma shape control device, comprising: an electrode which is fixed to an outer peripheral portion, forms an electric field (E) therein, and causes an E × B drift motion with respect to the plasma.