JPH1022096A - Inductively coupled plasma device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction coupling plasma device which restrains distortion of a plasma generating field, eliminates the fear of damaging the component parts of an insulating tube or the like, has high efficiency, and can be operated at high outputs. SOLUTION: A plurality of singly wound high frequency induction coils 2A, 2B, 2C are wound on a cylindrical electrically insulating tube 1 in such a way as to be coaxial with the tube 1 with a current loop surface being parallel to the cross section of the electrically insulating tube 1; a plasma gas is introduced from one end of the electrically insulating tube 1, and a high frequency current obtained at a high frequency power supply 3 is distributed by a high frequency current distributor 6, is adjusted and optimized by impedance adjusters 4A, 4B, 4C, and supplied to the high frequency induction coils 2A, 2B, 2C by a current transporting conductor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductively coupled plasma apparatus for generating thermal plasma using high frequency inductive coupling, and more particularly to a configuration having a high plasma output efficiency and a long life.

[0002]

2. Description of the Related Art Inductively Coupled Plasma (Inductively Coupled Plasma)
d Plasma (hereinafter abbreviated as ICP) is a device in which a high-frequency induction coil is wound coaxially around an electric insulating tube, a high-frequency current is applied to the high-frequency induction coil, and the gas introduced into the electric insulating tube is turned into plasma. Device.

FIG. 5 is a basic configuration diagram of a conventionally used inductively coupled plasma device (ICP device). In the figure, reference numeral 1 denotes a cylindrical electric insulating tube. Reference numeral 2 denotes a high-frequency induction coil wound coaxially on the electrically insulating tube 1, usually 3 to
It is wound four turns. Reference numeral 3 is a high-frequency power supply, 4 is an impedance adjuster, and 5 is a current transport conductor. In this configuration, a plasma gas is introduced from one end of the electric insulating tube 1, and a high-frequency current obtained by adjusting the output current of the high-frequency power supply 3 by the impedance adjuster 4 is supplied to the high-frequency induction coil 2 through the current transport conductor 5. , Generating a high-frequency magnetic field. The plasma gas introduced into the electric insulating tube 1 is turned into plasma by an electric field generated by electromagnetic induction of the generated high-frequency magnetic field. Obtained plasma output 10
Is formed in a divergent shape or a narrowed flare shape by controlling the strength and shape of the electric field and the radial and circumferential flow rates of the plasma gas introduced into the electric insulating tube 1.

An ICP device may be used as a hybrid torch in combination with a DC torch (see Japanese Patent Application Laid-Open No.
62-29880), and there is also an example in which multiple combinations are used to stabilize and extend the life (see JP-A-61-161138).

[0005]

As described above, the ICP
In the device, a high-frequency induction coil was coaxially wound around an electric insulating tube, a high-frequency current was applied to generate a high-frequency magnetic field, and the electric field was introduced into the electric insulating tube using an electric field formed by an electromagnetic induction action of the generated magnetic field. The gas is used as plasma. Therefore, the shape of the obtained plasma depends on the shape of the high-frequency magnetic field that generates the electric field, that is, the shape of the high-frequency induction coil.

On the other hand, in the conventional ICP device, as shown in FIG. 5, the high-frequency induction coil 1 is formed by a coil having a plurality of turns of 3 to 4 turns. Even if coaxially arranged, the conductor of the high-frequency induction coil 2 is spirally wound and has a slope with respect to the cross section of the electric insulating tube 1. The insulating pipe 1 has an inclination with respect to the axial direction. Further, in such a multi-turn coil, the start and end of the winding are arranged at the upper end and the lower end, so that the magnetic field generated by the current flowing through this portion is formed to be asymmetrically inclined. Therefore, the electric field for plasma generation generated by the electromagnetic induction of the high-frequency magnetic field is distorted or tilted. In particular, the tilt of the magnetic field at the lower end greatly affects the deviation of the shape of the electric field. For this reason, in the conventional ICP device, the generated plasma shape is not coaxial and is generated unevenly in the electric insulating tube 1, and the loss on the wall surface increases, and the efficiency of the plasma output decreases, or If the high-frequency current is increased to increase the plasma output, the energy of the biased plasma increases, and there is a risk that the electric insulating tube 1 and the surrounding components may be damaged.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, suppress the distortion of the plasma-generating electric field, eliminate the possibility of damaging the components such as the insulating tube, and operate with high efficiency and high output. It is to provide a possible inductively coupled plasma device (ICP device).

[0008]

In order to achieve the above object, in the present invention, a plasma gas is introduced into an electric insulating tube around which a high-frequency induction coil is wound, and a high-frequency current is supplied to the high-frequency induction coil. An IPC apparatus for converting the gas into plasma to use: (1) a high-frequency induction coil formed of a plurality of single-turn coils, and a high-frequency current applying means for applying a high-frequency current to each of the single-turn coils independently of each other; It shall be.

(2) Further, the high-frequency current supply means of (1) includes a single high-frequency power supply, a high-frequency current distributor for distributing a high-frequency current obtained by the high-frequency power supply to a plurality of single-turn coils, A plurality of current-carrying conductors for sending the high-frequency current obtained by distribution by the distributor to each single-turn coil,
And an impedance adjuster for controlling the supply amount of the high-frequency current.

(3) Alternatively, the high-frequency current supplying means of (1) is connected to a plurality of high-frequency power supplies provided independently for the plurality of single-turn coils, and each high-frequency power supply and each single-turn coil. A plurality of current transport conductors, an impedance adjuster for controlling the supply amount of the high-frequency current, and an oscillation phase adjuster for adjusting the oscillation of the plurality of high-frequency power supplies.

(4) Further, the IC of (2) or (3)
In the P device, a notch is provided in the current transport conductor to provide an impedance adjuster. IC as described in (1) above
If the high-frequency induction coil of the P device is to be formed from a plurality of single-turn coils, each single-turn coil can be provided with conductors arranged in parallel with the cross section of the electric insulating tube, so that the current loop Since the bias and the inclination are eliminated, the central axis of the generated magnetic field can be arranged so as to coincide with the central axis of the electric insulating tube. In particular, in the case of a single-turn coil, the start and end of winding of the conductor can be arranged in the same plane parallel to the cross section of the electrical insulating tube. A magnetic field with excellent symmetry can be obtained without generating a bias in the generated magnetic field. Accordingly, the high-frequency current passing means independently supplies a high-frequency current to each of the plurality of single-turn coils, so that a high-frequency magnetic field having a predetermined strength and shape and having no bias is formed. An unbiased plasma output is obtained by the electric field generated by the action.

Furthermore, if the above (2) is satisfied,
The high-frequency current distributed by the high-frequency current distributor and sent to each single-turn coil through the current transport conductor is controlled in the distribution amount by the impedance adjuster, so that the current balance caused by the system and the plasma load is prevented from being disrupted. A plurality of single-turn coils can be effectively driven by the high-frequency power supply.

According to the above (3), the dedicated high-frequency power supplies for driving a plurality of single-turn coils are driven in a coordinated and stabilized manner by an oscillation phase adjuster. A plurality of single-turn coils are effectively driven by the high-frequency power supply of the above. In addition, by adopting the above (4), the conductance and the inductance can be easily adjusted, and the adjustment of the high-frequency current supplied to the plurality of single-turn coils can be more effectively performed.

[0014]

FIG. 1 is a schematic diagram showing a first embodiment of an ICP device according to the present invention. FIG. 1A is a basic configuration diagram showing a configuration of an ICP device main body and a high-frequency current supply system.
(B) is a cross-sectional view of the ICP device main body on the XX plane of (a). As shown in the figure, the main body of the ICP device of this embodiment is configured by winding three single-turn high-frequency induction coils 2A, 2B, and 2C concentrically around a cylindrical electric insulating tube 1. . A double cylinder made of quartz glass is used for the electric insulating tube 1, and cooling water is passed through an intermediate layer of the double cylinder to cool the double cylinder. High frequency induction coils 2A, 2B, 2
A hollow copper tube is used for each of the coil conductors of C, and cooling water is passed through the inside to cool the coil. Each coil is adjusted and fixed by a jig (not shown) so that its plane coincides with the cross section of the electric insulating tube 1 and its axis coincides with the axis of the electric insulating tube 1.

The present embodiment employs a system in which three single-turn high-frequency induction coils 2A, 2B, and 2C are driven by one high-frequency power supply 3, and the high-frequency current is supplied to a high-frequency current distributor 6 And supplied to each coil by a current transport conductor 5 made of a hollow copper tube. The current balance of each coil is adjusted and optimized by adjusting the variable capacitance of the impedance adjusters 4A, 4B, 4C provided in each system. That is, if this method is used, the use efficiency can be increased and the device can be driven by one high-frequency power supply. Note that the impedance may be adjusted by using an inductance, but an optimum impedance adjustment element may be selected from the balance of the entire high-frequency system including the load.

In the ICP apparatus configured as described above, plasma gas is introduced from one end of the electric insulating tube 1 and supplied in the radial and circumferential directions, and at the same time, the high-frequency induction coils 2A,
When a high-frequency current is passed through 2B and 2C, a high-frequency magnetic field generated, that is, an electric field generated by electromagnetic induction of the high-frequency magnetic field is formed coaxially with the electric insulating tube 1 without any deviation, and the plasma output 10 is supplied to the electric insulating tube 1. Since it is formed coaxially in the inside, there is no risk of loss on the wall surface or damage to the wall surface, and plasma is generated with high efficiency.

FIG. 2 is a basic configuration diagram showing a second embodiment of the ICP apparatus according to the present invention. The configuration of the ICP device main body of the present embodiment is the same as the configuration of the ICP device main body of the first embodiment shown in FIG. 1, and the difference from the first embodiment of the present embodiment is that Wound high frequency induction coils 2A, 2B,
There is a 2C driving method. That is, the present embodiment employs a method in which three coils are driven by three high-frequency power supplies 3A, 3B, and 3C, and the high-frequency current supplied from each power supply is controlled by an impedance adjuster provided in each system. 4
A, 4B, and 4C adjust. In addition, in order to efficiently drive with a plurality of power supplies, oscillation coordination and stabilization of the power supplies are achieved by the oscillation phase adjuster 7.

Therefore, in the ICP device having this configuration, the high-frequency power supplies 3A, 3B, and 3C can be reduced in size and can supply a large current in the MHz region, which is technically difficult, and is proportional to the magnitude and frequency of the induced current. Since the electric field of the ICP device can be increased, a high-output ICP device can be obtained. 3 and 4 are external views showing an embodiment of an impedance adjuster used in a high-frequency current supply system of an ICP device according to the present invention. FIG. 3 shows a plate-like current transport conductor 5A and a cutout 9A. Is provided as an impedance adjuster, and FIG. 4 shows an impedance adjuster provided with a cutout 9B in a tubular current carrying conductor 5B.

By forming the cutouts 9A and 9B in this manner, the inductance in the circuit is mainly increased, and a simple structure can be easily applied to the plasma load without providing a special circuit element or a shield case for accommodating the circuit element. The power efficiency can be improved.

[0020]

As described above, according to the present invention, (1) Since the ICP device is configured as described in claim 1, the current loop of the high-frequency induction coil is formed in the cross section of the plasma generation space. The ICP can be arranged in a consistent manner and the distortion of the plasma generation electric field is suppressed, so that there is no danger of damage to the components such as the insulating tube, and the ICP capable of high-efficiency and high-power operation. The device was obtained.

(2) Further, according to the second aspect of the present invention, since a plurality of high frequency induction coils can be driven by one high frequency power supply with high utilization efficiency, damage to components can be prevented. It is suitable as an ICP device that can operate with high efficiency and high output without fear. (3) Further, if the configuration is made as described in claim 3, each power supply can be downsized, a large current in the MHz range can be supplied, and a high-output ICP device can be obtained.

(4) According to the fourth aspect, the impedance can be easily adjusted, and the power efficiency with respect to the plasma load can be easily increased with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an ICP device according to the present invention, in which (a) is a basic configuration diagram showing a configuration of an ICP device main body and a high-frequency current supply system, and (b) is a configuration diagram of (a). XX
Sectional view of the ICP device main body in the plane

FIG. 2 is a basic configuration diagram showing a second embodiment of the ICP apparatus according to the present invention.

FIG. 3 is an external view showing an embodiment of an impedance adjuster used in a high-frequency current supply system of an ICP device according to the present invention.

FIG. 4 is an external view showing another embodiment of the impedance adjuster used in the high-frequency current supply system of the ICP device according to the present invention.

FIG. 5 is a basic configuration diagram of a conventionally used ICP apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric insulating tube 2 High frequency induction coil 2A High frequency induction coil 2B High frequency induction coil 2C High frequency induction coil 3 High frequency power supply 3A High frequency power supply 3B High frequency power supply 3C High frequency power supply 4 Impedance adjuster 4A Impedance adjuster 4B Impedance adjuster 4C Impedance adjuster 5 Current Transport conductor 5A Current transport conductor 5B Current transport conductor 6 High-frequency current distributor 7 Oscillation phase adjuster 9A Notch 9B Notch 10 Plasma output

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasushi Sakakibara 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Fuji Electric Co., Ltd.

Claims (4)

[Claims] An inductively coupled plasma apparatus for introducing a plasma gas into an electric insulating tube around which a high-frequency induction coil is wound, applying a high-frequency current to the high-frequency induction coil, and converting the gas into plasma. Comprises a plurality of single-turn coils, and high-frequency current applying means for applying a high-frequency current to each of the single-turn coils independently of each other. 2. An inductively coupled plasma apparatus according to claim 1, wherein said high-frequency current supplying means distributes a high-frequency current obtained by said high-frequency power supply to a plurality of single-turn coils. It is characterized by comprising a distributor, a plurality of current-carrying conductors for sending a high-frequency current obtained by distribution by the high-frequency current distributor to each single-turn coil, and an impedance adjuster for controlling a supply amount of the high-frequency current. Inductively coupled plasma device. 3. The inductively coupled plasma apparatus according to claim 1, wherein said high-frequency current supply means includes a plurality of high-frequency power supplies provided independently for a plurality of single-turn coils, An inductive coupling comprising: a plurality of current transport conductors connecting a single-turn coil; an impedance adjuster for controlling a supply amount of a high-frequency current; and an oscillation phase adjuster for adjusting oscillation of a plurality of high-frequency power supplies. Plasma equipment. 4. An inductively coupled plasma apparatus according to claim 2, wherein said impedance adjuster comprises a cutout provided in a current transport conductor.