JP3577843B2 - Inductively coupled plasma device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inductively coupled plasma apparatus that generates thermal plasma using high-frequency inductive coupling, and more particularly to a configuration having a high plasma output efficiency and a long life.
[0002]
[Prior art]
An inductively coupled plasma (hereinafter, abbreviated as ICP) device has a high-frequency induction coil wound coaxially around an electrically insulating tube, and a high-frequency current is applied to the high-frequency induction coil to introduce a gas introduced into the inside of the electrically insulating tube. This is an apparatus that is used by converting it into plasma.
[0003]
FIG. 5 is a basic configuration diagram of an inductively coupled plasma device (ICP device) conventionally used. In the figure, reference numeral 1 denotes a cylindrical electric insulating tube. Reference numeral 2 denotes a high-frequency induction coil wound coaxially around the electric insulating tube 1 and is usually wound three to 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 an 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. And generate 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. The 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.
[0004]
The ICP device may be used as a hybrid torch in combination with a DC torch (see JP-A-62-29880), or may be used in multiple stages to stabilize and extend the service life (see JP-A-61-1986). 161138).
[0005]
[Problems to be solved by the invention]
As described above, in an ICP device, a high-frequency induction coil is coaxially wound around an electric insulating tube, a high-frequency current is applied to generate a high-frequency magnetic field, and the electric field is generated using an electric field formed by an electromagnetic induction action of the generated magnetic field. The gas introduced into the insulating tube is used as a 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.
[0006]
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 it is arranged, the conductor of the high-frequency induction coil 2 is spirally wound and has an inclination with respect to the cross section of the electric insulating tube 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.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks, suppress distortion of a plasma-generating electric field, eliminate the possibility of damage to components such as an insulating tube, and provide a high-efficiency, high-output operation guide. An object of the present invention is to provide a coupled plasma device (ICP device).
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
In an IPC device that introduces a plasma gas into an electric insulating tube around which a high-frequency induction coil is wound and passes a high-frequency current to the high-frequency induction coil to convert the gas into plasma,
(1) The high-frequency induction coil is formed from 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 is provided.
[0009]
(2) Further, the high-frequency current supply means of (1) is provided by one high-frequency power supply, a high-frequency current distributor that distributes a high-frequency current obtained by the high-frequency power supply to a plurality of single-turn coils, and a high-frequency current distributor. A plurality of current transport conductors for sending the distributed high-frequency current to each of the single-turn coils, and an impedance adjuster for controlling the supply of the high-frequency current are provided.
[0010]
(3) Alternatively, the high-frequency current supply means of (1) may include a plurality of high-frequency power supplies independently provided for the plurality of single-turn coils, and a plurality of high-frequency power supplies and the single-turn coils connected to each other. It comprises a current transport conductor, an impedance adjuster for controlling the supply amount of the high-frequency current, and an oscillation phase adjuster for adjusting the oscillation of a plurality of high-frequency power supplies.
[0011]
(4) Further, in the ICP device of (2) or (3), a notch is provided in the current transport conductor to form an impedance adjuster.
If the high-frequency induction coil of the ICP device is formed of a plurality of single-turn coils as described in (1) above, each of the single-turn coils should be provided with a conductor arranged in parallel with the cross section of the electric insulating tube. Therefore, the bias and the inclination of the current loop are eliminated, and the center axis of the generated magnetic field can be arranged so as to coincide with the center 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 is supplied to each of the plurality of single-turn coils independently by the high-frequency current supplying means, whereby 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.
[0012]
Further, according to the above (2), the distribution amount of 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 by the impedance adjuster. Disruption of the current balance caused by the load is prevented, and a single high-frequency power supply can effectively drive a plurality of single-turn coils.
[0013]
Further, according to the above (3), the dedicated high-frequency power supplies for driving the plurality of single-turn coils are driven while being oscillated and coordinated with each other by the oscillation phase adjuster. Thus, a plurality of single-turn coils are effectively driven.
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]
BEST MODE FOR CARRYING OUT THE INVENTION
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). It is sectional drawing of the ICP apparatus main body in XX plane.
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 it. Hollow copper tubes are used for the coil conductors of the high-frequency induction coils 2A, 2B, and 2C. Each coil is adjusted and fixed by a jig (not shown) so that the plane is aligned with the cross section of the electrical insulating tube 1 and the axis is aligned with the axis of the electrical insulating tube 1.
[0015]
Further, in the present embodiment, a method is adopted in which three single-turn high-frequency induction coils 2A, 2B, and 2C are driven by one high-frequency power supply 3, and a high-frequency current is distributed by a high-frequency current distributor 6. Are 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 using an inductance, but an optimum impedance adjustment element may be selected from the balance of the entire high-frequency system including the load.
[0016]
In the ICP device configured as described above, when a plasma gas is introduced from one end of the electric insulating tube 1 and supplied in the radial direction and the circumferential direction, and a high-frequency current is applied to the high-frequency induction coils 2A, 2B, and 2C at the same time, a high-frequency magnetic field is generated. Therefore, an electric field generated by the 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 formed coaxially inside the electric insulating tube 1. The plasma is generated with high efficiency without the risk of loss or damage to the wall surface.
[0017]
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 three single There is a driving method of the wound high frequency induction coils 2A, 2B, 2C. That is, in this embodiment, three coils are driven by three high-frequency power supplies 3A, 3B, and 3C, and a high-frequency current supplied from each power supply is supplied to an impedance adjuster provided in each system. It is adjusted by 4A, 4B, 4C. In addition, in order to drive efficiently with a plurality of power supplies, oscillation coordination and stabilization of the power supplies are achieved by the oscillation phase adjuster 7.
[0018]
Therefore, in the ICP device having this configuration, the high-frequency power supplies 3A, 3B, and 3C can be reduced in size, can supply a large current in the MHz range where technical difficulty is high, and can be used in an ICP device that is proportional to the magnitude and frequency of the induced current. Since the electric field 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. FIG. 4 shows a configuration in which a notch 9B is provided in a tubular current carrying conductor 5B to form an impedance adjuster.
[0019]
By forming the cutouts 9A and 9B in this way, the inductance in the circuit is mainly increased, and the power efficiency with respect to the plasma load can be easily increased by a simple configuration without providing a special circuit element or a shield case for accommodating the circuit element. Can be raised.
[0020]
【The invention's effect】
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 can be arranged in conformity with the cross section of the plasma generation space, and the distortion of the plasma generation electric field can be improved. Therefore, an ICP device capable of high-efficiency, high-output operation without a risk of damage to components such as an insulating tube can be obtained.
[0021]
(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 source with high utilization efficiency, there is no possibility of damage to components. It is suitable as an ICP device that can operate with high efficiency and high output.
(3) Further, if the configuration is made as described in claim 3, each power supply can be reduced in size, a large current in the MHz range can be supplied, and a high-output ICP device can be obtained.
[0022]
(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). FIG. 2 is a cross-sectional view of the ICP device main body in the XX plane. FIG. 2 is a basic configuration diagram showing a second embodiment of the ICP device according to the present invention. FIG. 3 is an impedance adjustment used in a high-frequency current supply system of the 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 apparatus according to the present invention. FIG. 5 is a view showing the conventional ICP apparatus. Basic configuration diagram [Description of reference numerals]
REFERENCE SIGNS LIST 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

Claims (4)

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 applied to the high-frequency induction coil to convert the gas into plasma.
An inductively coupled plasma apparatus, wherein the high-frequency induction coil 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. 2. The inductively coupled plasma apparatus according to claim 1, wherein the high-frequency current supply means distributes a high-frequency current obtained by the high-frequency power supply to a plurality of single-turn coils. An inductively coupled plasma device comprising: a plurality of current transport conductors for sending a high-frequency current obtained by distribution by a current distributor to each single-turn coil; and an impedance adjuster for controlling a supply amount of the high-frequency current. 2. The inductively coupled plasma device according to claim 1, wherein the high-frequency current supply means includes a plurality of high-frequency power supplies provided independently for the plurality of single-turn coils, each high-frequency power supply and each single-turn coil. An inductively coupled plasma device comprising: a plurality of current transport conductors connected to each other; 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. 4. The inductively coupled plasma device according to claim 2, wherein the impedance adjuster comprises a cutout provided in the current transport conductor.

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