JP2001357999A - Plasma generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma generating device generating plasma at the atmospheric pressure in an atmosphere of only air without another specific gas, utilizing high frequency wave discharge like microwave, restraining power consumption, with stable life. SOLUTION: The plasma generating device comprises an oscillation means generating high frequency wave, a circuit means treating high frequency wave generated at the oscillation means, a transmission means transmitting the high frequency wave treated by the circuit means, and a plasma generation means generating plasma by using the high frequency wave transmitted by the transmission means. A plasma excitation member, forming a concentrated electric field between a resonance cavity in which, electric field component and magnetic field component of the transmitted high frequency wave is locked up by the plasma generation means, and electric field component of the high frequency wave generated in a cavity chamber as a cavity resonator, is vertically erected in the cavity chamber, and constructed by a copper rod with stainless screw at top end, and tungsten or metal plate as a copper rod arranged vertically to the copper rod at lower part of the top part of the copper rod.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a plasma generator utilizing a high-frequency electric wave discharge such as a microwave.

[0002]

2. Description of the Related Art A plasma generator using a high-frequency discharge is used, for example, as a plasma CVD apparatus, a plasma etching apparatus, or a sputtering apparatus in the manufacture of semiconductors.

[0003] Various tests and studies have been made on a high-frequency plasma generator, and various types have been proposed.
Almost all of such plasma generators essentially include a vacuum container whose inside is maintained at a low pressure, a coil that is a high-frequency antenna spirally wound around the outer periphery of the vacuum container, and a high-frequency current supplied to the coil. High frequency oscillator.

In such a conventional plasma generator, after the vacuum vessel is discarded, a gas for generating plasma is introduced into the vacuum vessel and maintained at an appropriate pressure.

Next, a high-frequency current is supplied to the coil. The coil supplied with the high-frequency current generates a magnetic field by electromagnetic induction around the coil as a high-frequency antenna. Among these, an electric field is induced in the vacuum container by the magnetic field generated in the vacuum container, whereby the gas in the vacuum container is ionized and plasma is generated.

[0006] A plasma generator capable of generating a plasma flame in an atmosphere of only air at atmospheric pressure by microwaves is disclosed in Japanese Patent Publication No. 7-11996.

Japanese Patent Publication No. 7-11996 discloses a transmitter 1a, a three-dimensional circuit 1b, a corner 13a,
As shown in FIG. 10, the plasma generating unit 1d is composed of a closed cavity container and a plasma excitation member 14 provided in the cavity container. A high-frequency electric wave is confined in the cavity resonator 5 to induce a high electric field and a high magnetic field, and an electric field is concentrated between the high electric field and the plasma exciting member 14. In this atmosphere, a large-scale plasma flame can be generated by an inexpensive device with a simple structure in an atmosphere of the type described above.

[0008]

However, the conventional plasma generator requires a very high power of 4 to 5 kW to generate plasma. In addition, there is a problem that generation and lifetime of plasma are unstable.

Therefore, according to the present invention, the electric power is reduced under the condition that the pressure inside the predetermined hollow container is set to the atmospheric pressure, and there is no other gas in the hollow container but only air. It is an object of the present invention to provide a plasma generation device capable of suppressing the generation of plasma and stably generating plasma.

[0010]

SUMMARY OF THE INVENTION The present invention provides an oscillating means for generating a high-frequency radio wave, a circuit means for processing the high-frequency radio wave generated by the oscillating means, and a transmission means for transmitting the high-frequency radio wave processed by the circuit means. Means, and plasma generating means for generating plasma using the high-frequency radio wave transmitted by the transmitting means, and the plasma generating means includes a cavity for confining the electrolytic component and the magnetic field component of the transmitted high-frequency radio wave inside. A plasma excitation member for forming a concentrated electric field between the resonator and the high-frequency electrolytic component provided in the hollow container which is the cavity resonator is vertically set in the hollow container, and has a stainless steel screw at the tip. And a metal piece that is a tungsten or copper bar provided perpendicularly to the copper bar at the lower end of the copper bar. Is a plasma generating apparatus characterized.

[0011]

In the present invention, when a high-frequency wave is transmitted into a cavity formed of a closed cavity and a plasma exciting member protruding from the cavity, the electric field component and the magnetic field of the high-frequency wave are transmitted. The components are confined in the cavity and a strong electric field and a high magnetic field are induced. A concentrated electric field is formed between the strong electric field and the plasma excitation member, and plasma is stably generated with low power under atmospheric pressure and in air.
A fireball discharge is captured.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a plasma generator according to the present invention. FIG. 1 is a block diagram showing a schematic configuration of a plasma generator of the present invention, and FIGS.
FIG. 4 shows an external view of the plasma generator of the present invention. First, the configuration of the plasma generator will be described in detail.

As shown in FIG. 1, a power supply unit 1e and a transmitting unit 1
a, a three-dimensional circuit unit 1b, an operation control unit 1f, a transmission unit 1c, and a plasma generation unit 1d, a power supply unit 1e, a transmission unit 1a that generates high-frequency radio waves such as microwaves, a three-dimensional circuit unit 1b, and operation control. A high-frequency oscillator is constituted by the unit 1f.

In the power supply unit 1e, the number of input phases is three,
The input voltage is 200v / 220v ± 10% (switching method by short bar), the input frequency is 50Hz / 60Hz, and the rectification method is a three-phase full-wave rectification method.

The oscillating unit 1a is a microwave oscillator using a magnetron having an oscillating frequency of 2450 ± 30 MHz, an oscillating output of 500 W to 5 KW, and an output stability of ± 5% for a variation of ± 10% of the power supply voltage at an output of 5 kW. 5% or less, power ripple 10% or less at 5KW output, cooling method is water cooling (magnetron), air cooling (magnetron heater, antenna)
It is.

The operation control section 1f operates and controls the power supply section 1e and the three-dimensional circuit section 1b.

The transmission circuit section 1c includes a power supply section 1e, a transmission section 1
a, transmitting a high-frequency wave generated by the three-dimensional circuit unit 1b and the operation control unit 1f.

The plasma generating section 1d generates plasma by using the high frequency radio wave transmitted by the transmission circuit section 1c and a plasma exciting member provided in the plasma generating section.

Hereinafter, the present invention will be described in detail with reference to the external views of the plasma generator shown in FIGS. FIG. 2 is a front view of a plasma generator according to the present invention, FIG. 3 is a front view of a three-dimensional circuit part of the plasma generator according to the present invention, and FIG. 4 is a plan view of a three-dimensional circuit part of the plasma generator according to the present invention. is there.

As shown in FIG. 2, the plasma generator 1
Has a structure including a transmission unit 1a, a three-dimensional circuit unit 1b, a transmission unit 1c, and a plasma generation unit 1d.

The transmitting section 2 is connected to a tapered tube 3, which is connected to an isolator 3a, and the isolator 3a is connected to a directional coupler 3b and an EH tuner 3e to constitute a circuit element. .

The tapered tube 3 connects the oscillation section 2 and the isolator 3a without reflection. The isolator 3a transmits a radio wave with almost no attenuation in one direction, but transmits an output radio wave from the oscillation unit 2 because it is a waveguide that absorbs in the reverse direction and hardly transmits the radio wave.

Numerals 2b and 2d shown in FIG. 3 are cooling pipes.

The directional coupler 3b includes a coaxial attenuator 3c and a crystal mount 3d, respectively.
It is used to measure microwaves, and the direction of transmission of power going out to the sub-wire differs depending on the direction of power transmission on the main wire. The directional coupler 3b is 2
One unit detects the reflected power and the other detects the traveling wave power.

The EH tuner 3e has an adjustment knob 3f. By adjusting the knob 3f, the oscillation unit 2 is connected to the plasma generation unit 1 as a load described later.
This is to match with d.

The transmission section 4 has conventionally been composed of waveguides 13, 13,... And corners 13a, 13a or bends as shown in FIG. Uses only the straight waveguide 4 as shown in FIG.

Compared with the conventional art, the conventional corner part is shown in FIG.
As shown in (2), there were two corners 13a, but all were removed in the plasma generator 1 of the present invention, and only the straight waveguide 4 was formed.

A cavity 5 is used for the plasma generating section 1d.

As described above, when the external appearance of the plasma generator according to the present invention is compared with the conventional diagram shown in FIG. 9 as shown in FIG.
The whole shape has been changed. As a result, the energy loss of the microwave is greatly reduced by removing the corner portion and the waveguide, so that the plasma generated at 4 to 5 kW in the past can be generated at 2 kW or even less in some cases. When the output was increased to 5 kW, plasma emitting strong light came to be generated.

Next, FIGS. 5 and 6 show Embodiment 1 of the plasma excitation member in the cavity resonator, and FIGS. 7 and 8 show Embodiment 2 of the plasma excitation member in the cavity resonator. The generation of plasma in the cavity, which is a resonator, will be described in detail.

As shown in FIG. 5, the plasma excitation member 7
Is vertically set in the hollow container 6, and has a copper round bar 7a provided with a stainless steel screw 7b at the end thereof, and tungsten or copper provided vertically below the copper round bar 7a at the lower end of the copper round bar 7a. And a metal piece 7c which is a rod.

The cavity resonator 5 is cylindrical, and a plasma excitation member 7 is provided inside the cavity resonator 5 at a center position of the cavity resonator 5 in parallel with the longitudinal direction. .

As an example, a closed surface is made of metal for confining microwaves. At that time, in order to reduce the loss of the microwave energy, the cavity 5 has a cylindrical shape and a diameter of 161 mm (= 1.318λ, λ: 122 mm in wavelength).
The length of the cylinder was about 3λ. Both ends of the cylindrical tube need to be closed, but one end was filled with an aluminum mesh plate to make it movable, and the other end was sealed with aluminum foil to be fixed. The reason for using the aluminum mesh plate is to enable the inside of the resonator to be observed.

The inside of the cavity 5 is set to the same atmospheric pressure as the outside, and the gas in the cavity 6 as the cavity 5 is made only of air.

As shown in FIGS. 5 and 6, the plasma excitation member 7 is formed by vertically inserting a copper round bar 7a (diameter: 10 mm, height: 100 mm) on the left side of a hollow cavity 6 which is a cylindrical cavity resonator 5. A stainless steel screw 7b is attached to the tip of the copper round bar 7a.
(Diameter: 3 mm, height: 10 mm), and tungsten or copper is placed under the stainless screw (7b) (upper copper round bar (7a)) so that it is parallel to the longitudinal direction of the cavity resonator (5) and the tip is at the center. Rod metal piece 7c (diameter 1 mm, length 120
mm).

The plasma generating member 1d of the plasma generator 1 shown in FIGS. 1 to 3 is combined with the plasma exciting member 7 shown in FIG. 5 to generate plasma. As a result, as shown in FIG. Plasma was generated in a form floating in the upper part of the cavity vessel 6 which was 5. At that time, plasma was stably present as long as the microwave was injected.

FIGS. 7 and 8 show a second embodiment of the plasma exciting member in the cavity resonator. As shown in FIG. 7, a plasma excitation member 10 is vertically set in a hollow container 6, and a copper round bar 10 provided with stainless steel screws 10b and 10d at the tips.
a, 10c, two copper bars 10a, 10c
A metal piece 10e, which is a tungsten or copper rod, is provided vertically below the copper round rods 10a and 10c at the lower end between them.

As shown in FIG. 7, the plasma exciting member 10 in the cavity 6 is a cylindrical cavity resonator 5 in the cavity 6.
Copper round bar 10c (diameter 10mm, height 100m)
m) is set up vertically, and a stainless steel screw 10d (diameter 3 mm, height 10 mm) is provided at the tip of the copper round bar 10c.
Similarly, a copper round bar 10a and a stainless steel screw 10b are set up vertically at a distance of 100 mm in parallel with the longitudinal direction in the cavity 6 as the cavity resonator 5. Both stainless screws 10
b, 10d, a metal piece 10e (diameter 1 mm, length 120 mm) of a tungsten or copper rod is provided below (under the copper round rods 10a, 10c).

The plasma generating member 1d of the plasma generator 1 shown in FIGS. 1 to 3 is combined with the plasma exciting member 10 shown in FIG. 7 to generate plasma, and as a result, a cavity resonator is formed as shown in FIG. 5 is a stainless steel screw 10b provided at the tip of a copper round bar 10a, which is set up 100 mm away from the copper round bar 10c, which is set up perpendicularly to the center of the cavity 6 inside the hollow container 5, in parallel with the longitudinal direction of the cavity resonator 5. Plasma was generated. At that time, plasma was stably present as long as the microwave was injected.

Further, the operation of the plasma generator according to the embodiment of the present invention will be described.

First, as shown in FIG. 1, AC power is rectified from a power supply unit 1e and DC power is supplied to an oscillation unit 1a. The oscillating unit 1a performs an oscillating operation by receiving DC power from the power supply unit 1e as input, and generates high-frequency power. Oscillator 1
The output power of a is transmitted to the plasma generation unit 1d through the three-dimensional circuit unit 1b and the transmission circuit unit 1c. Operation control unit 1f
Monitors the current of the power supply unit 1e, performs these controls, stabilizes the current, and thereby stabilizes the radio wave output from the oscillation unit 1a.

Further, the high frequency (hereinafter, referred to as "high frequency")
“Microwave”. ) The radio wave, as shown in FIG.
The reflection is made non-reflective by the tapered tube 3 of the three-dimensional circuit portion 1b, and transmitted to the directional coupler 3b through the isolator 3a. In the directional coupler 3b, the power component of the traveling wave and the power component of the reflected wave are detected.

The operation control unit 1f shown in FIG. 1 monitors these power components, and also controls the directional coupler 3 shown in FIG.
b controls the traveling wave power component.

The microwave from the directional coupler 3b is EH
It is guided to the transmission circuit section 1c through the tuner 3e. Here, the EH tuner 3e attempts to match the microwave power guided from the directional coupler 3b with the load, and
The microwave power traveling in the straight waveguide 4 of c is set to the same condition as the non-reflection.

As described above, the transmitting section 1a and the three-dimensional circuit section 1b
The generated microwave is transmitted to the plasma generation unit 1d via the straight waveguide 4 of the transmission circuit unit 1c.

In the cavity resonator 5 of the plasma generating section 1 d, the microwave transmitted from the straight waveguide 4 forms a standing wave in the cavity 6, which is the cavity resonator 5, and is confined.

A strong electric field and a strong magnetic field are induced by the confinement effect, and concentrated electrolysis is formed between the strong electric field and the plasma excitation members 7 and 10 shown in FIGS. 5 and 7. Strong electrolytic concentration is performed in the concentration portions 8 and 11.

The gas (air) in the hollow container 6 is ionized by the electrolytic concentration, and plasma is generated in the vicinity of the electrolytic concentration portions 8 and 11 under the atmospheric pressure (not at a low pressure or in a vacuum) to generate a fire ball. .

According to the experimental results, by using the excitation member 7 shown in FIGS. 5 and 6, the excitation member 7 is floated above the cavity 6 as the cavity resonator 5 as shown in FIG. Plasma was generated.

Also, by using the excitation member 10 shown in FIGS. 7 and 8, plasma was generated in the stainless steel screw 10b provided on the upper part of the one (left) barrel round bar 10a as shown in FIG.

Both the excitation members 7 and 8 stably generated plasma as long as microwaves were being injected.

[0052]

Since the present invention has the above-described configuration, the following effects can be obtained. First, microwave energy loss is greatly reduced by removing the conventional transmission section.

Second, by improving the excitation member,
Plasma has been easily and stably generated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a plasma generator according to the present invention.

FIG. 2 is a front view of the plasma generator according to the present invention.

FIG. 3 is a front view of a three-dimensional circuit portion of the plasma generator according to the present invention.

FIG. 4 is a plan view of a three-dimensional circuit section of the plasma generator according to the present invention.

FIG. 5 is a sectional view of Embodiment 1 of the cavity resonator in the plasma generator according to the present invention.

FIG. 6 is a cross-sectional view of the cavity resonator when plasma is generated in FIG.

FIG. 7 is a sectional view of Embodiment 2 of the cavity resonator in the plasma generator according to the present invention.

8 is a cross-sectional view of the cavity resonator when plasma is generated in FIG.

FIG. 9 is a front view of a conventional plasma generator.

FIG. 10 is a sectional view of a cavity resonator in a conventional plasma generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma generator 1a Transmission part 1b Three-dimensional circuit part 1c Transmission part 1d Plasma generation part 1e Power supply part 1f Operation control part 2 Transmission part 2a Cooling pipe 3 Tapered pipe 3a Isolator 3b Directional coupler 3c Coaxial attenuator 3d Crystal mount 3e EH Tuner 3f Adjusting knob 4 Straight waveguide 5 Cavity resonator 6 Inside cavity 7 Exciting member 7a Copper round bar 7b Screw 7c Metal piece 8 Electrolytic concentrating part 9 Plasma 10 Exciting member 10a, 10c Member 10b, 10d Screw 11 Electrolytic concentrating Part 12 plasma 13 straight waveguide 13a corner 14 excitation member

Claims (2)

[Claims] 1. Oscillating means for generating a high-frequency radio wave, circuit means for processing the high-frequency radio wave generated by the oscillating means, transmission means for transmitting the high-frequency radio wave processed by the circuit means, and transmission by the transmission means Plasma generating means for generating plasma using the transmitted high-frequency radio waves, the plasma generating means comprising a cavity for confining the electrolytic component and the magnetic field component of the transmitted high-frequency radio waves, and the cavity A plasma excitation member that forms a concentrated electric field between the high-frequency electrolytic component provided in the cavity container that is a resonator is vertically set in the cavity container,
It is characterized by being constituted by a copper round bar provided with a stainless steel screw at the tip, and a metal piece that is a tungsten or copper bar provided vertically below the copper round bar at the lower end of the copper round bar. Plasma generator. 2. A plasma exciting member is vertically set in a hollow container, and two copper round bars provided with stainless steel screws at the ends are set up in parallel. 2. The plasma generator according to claim 1, further comprising: a metal piece that is a tungsten or copper rod provided perpendicular to the plasma generator.