JPH07263184A - Microwave plasma generating device - Google Patents

Abstract

PURPOSE:To provide a microwave plasma generating device capable of efficiently introducing microwaves and generating high density plasma and large area plasma. CONSTITUTION:Hydrogen gas from a plasma generating gas source 42 and caesium gas from a specified gas source 38 are introduced into a discharge container 31 for generating plasma, and microwaves are introduced by a wave guide 47 having a positive potential with respect to the discharge container 31. Caesium gas whose ionization potential is lower than that of hydrogen gas is ionized at first by introduction of the microwaves to easily cause the following discharge. Absorption of the microwave is easily conducted, reflecting power is decreased, and the microwave is efficiently introduced. As a result, high density plasma and large area plasma are produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma generator used as a plasma source or an ion source for various devices.

[0002]

2. Description of the Related Art Conventionally, a microwave plasma generator is
It is used for an ion source of a neutral particle heating device for nuclear fusion, a plasma source of a plasma dry etching device and a plasma vapor phase growth device used for manufacturing a semiconductor device, and the like. Then, a microwave is introduced into the large-sized device for generating plasma by introducing high-power microwave of several hundreds watts or more into the discharge vessel with these devices.

A conventional example of an ion source, which is one of microwave plasma generators, will be described below with reference to FIGS. 5 and 6. FIG. 5 is a sectional view showing a schematic configuration of a conventional example, and FIG. 6 is an enlarged sectional view showing an essential part of FIG.

In FIGS. 5 and 6, reference numeral 1 is a discharge vessel, and a microwave introduction port 3 is formed in an upper plate 2 of the discharge vessel 1. The microwave introduction port 3 is attached so that one end of a waveguide 5 for introducing microwaves from a microwave generation source (not shown) into the discharge vessel 1 through the vacuum window 4 is opened inside the discharge vessel 1. It is formed by doing. Reference numeral 6 denotes a permanent magnet arranged on the outer surface of the discharge vessel 1 to form a magnetic field inside the discharge vessel 1. In addition, 7 is a magnetic force line schematically shown.

Further, in the discharge vessel 1, a plasma generation gas such as hydrogen or deuterium whose flow rate is adjusted by a leak valve 9 from a plasma generation gas source 8 is supplied from a gas introduction port 11 through an introduction pipe 10. It has become.
Further, an electrode portion 14 configured by providing an insulating material 13 between a plurality of extraction electrodes 12 for extracting an ion beam from the discharge vessel 1 to the outside is attached to the open lower end surface of the discharge vessel 1. In addition, in each extraction electrode 12 of the electrode portion 14,
In order to extract an ion beam from the plasma generated inside the discharge vessel 1, a predetermined voltage is applied by a power source (not shown).

In such a structure, the microwave propagating from the waveguide 5 is introduced into the discharge vessel 1, and the plasma-producing gas is discharged by the interaction with the magnetic field formed by the permanent magnet 6 to discharge. A plasma is generated in the container 1. Ions in the discharge plasma are extracted as an ion beam by applying a voltage to the extraction electrode 12 of the electrode unit 14, respectively.

At this time, the discharge vessel 1, the upper plate 2 and the waveguide 5
, The discharge plasma partially penetrates into the waveguide 5. And the discharge vessel 1 and the waveguide 5
A plasma sheath is formed between the inner wall surface and the plasma. Reference numeral 15 schematically shows the position of the beginning of the plasma sheath in which the electrical neutralization of the plasma is maintained.

Further, the inside of the waveguide 5 has no magnetic field or a weak magnetic field region even if there is a magnetic field. When a microwave is incident on such a substantially no magnetic field region, its plasma surface In the vicinity, part of the microwave will be reflected.

When the plasma density inside the waveguide 5 is further increased, the microwaves are totally reflected and a cutoff phenomenon occurs, so that the microwaves are not introduced into the discharge vessel 1. In the case of the frequency of 2.45 GHz often used for microwave discharge, the cutoff density is about 7 × 10 ¹⁰ cm ⁻³ .

As described above, in the microwave plasma generator using the waveguide 5, the microwave existing in the discharge vessel 1 cannot be sufficiently introduced due to the plasma existing inside the waveguide 5. It was difficult to generate a high density plasma in the No. 1 chamber.

In order to cope with such a situation, the applicant can reduce the reflection of microwaves by lowering the density of plasma existing in the waveguide so that the microwaves can be sufficiently introduced into the discharge vessel. We have proposed a microwave plasma generator.

The outline of the microwave plasma generator proposed by the applicant will be described below as a comparative example with reference to FIGS. 7 and 8. FIG. 7 is a sectional view showing a schematic configuration of a comparative example, and FIG. 8 is an enlarged sectional view showing an essential part of FIG.

In FIGS. 7 and 8, reference numeral 16 is a discharge vessel, the upper opening of which is closed by attaching an upper plate 19 to an upper flange 17 via an insulating member 18.
Then, one end of the waveguide 5 is attached to the microwave introduction port 3 formed in the upper plate 19.

Further, in each extraction electrode 12 of the electrode portion 14,
In order to extract the ion beam from the plasma generated inside the discharge vessel 16, a predetermined voltage is applied by connecting to a corresponding terminal of the power supply 20.
On the other hand, the waveguide 5, which is electrically insulated from the discharge vessel 16 by the insulating member 18, is connected to the voltage variable power source 21 via the switch 22, and the discharge vessel 16 is closed by closing the switch 22. On the other hand, it has a predetermined positive potential.

In such a structure, the discharge vessel 16
A plasma-generating gas such as hydrogen or deuterium is supplied into the chamber, and the microwave propagating from the waveguide 5 is introduced, and the plasma-generating gas is discharged by the interaction with the magnetic field formed by the permanent magnet 6, and the discharge is performed. A plasma is generated in the container 1. However, since the upper plate 19 and the waveguide 5 have a predetermined positive potential with respect to the discharge container 16, charged particles cannot exist in the vicinity of the microwave introduction port 3.

Then, the plasma is pushed back toward the inside of the discharge vessel 16 and does not enter the waveguide 5, and the electrical neutralization, which is shown schematically in FIG. The plasma sheath which is dripping, discharge vessel 16, upper plate 19,
It is formed between the inner wall surface of the waveguide 5 and the plasma.

As a result, the plasma density in the waveguide 5 is lowered and the microwave can be introduced into the discharge vessel 16. Further, since there is a magnetic field formed by the permanent magnet 6 in the discharge vessel 16, the introduced microwave efficiently ionizes the plasma-generated gas by the interaction with the magnetic field, and the discharge vessel 16
The density of the plasma generated inside becomes high.

However, even in the apparatus having such a structure, when the plasma density in the discharge vessel 16 is further increased, or the power of the microwave to be introduced and the pressure of the plasma generating gas are increased, the same as in the conventional example. At the same time, plasma comes to exist inside the waveguide 5, and its plasma density starts to rise. This is because the outflow of plasma from the high-density discharge vessel 16 into the waveguide 5 increases, and the increased microwave power and gas density increase the ionization in the waveguide 5.

Therefore, even if the density of the plasma generated in the discharge vessel 16 is further increased, the microwaves are reflected in the waveguide 5 and cannot be introduced into the discharge vessel 16, and the plasma is kept constant. It cannot be higher than the density, and the plasma is localized,
It was not possible to generate high-density plasma or large-area plasma. In the ion source, which is one of the microwave plasma generators, the increase of the plasma density in the discharge vessel 16 is hindered, and the current value of the ion beam that can be extracted cannot be increased.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and an object thereof is to efficiently introduce a microwave having a large power into a discharge vessel by a waveguide. Microwave plasma generation that can be performed and can generate high-density plasma or large-area plasma in the discharge vessel, and in the one used as an ion source, can extract an ion beam with a larger current value. To provide a device.

[0021]

SUMMARY OF THE INVENTION A microwave plasma generator of the present invention comprises a discharge vessel in which a plasma-generating gas is introduced into a depressurized interior to form plasma, and a microwave introduction port of the discharge vessel having one end. In a microwave plasma generator equipped with a waveguide for introducing a microwave into the discharge container and a magnetic field forming means for forming a magnetic field inside the discharge container, The present invention is characterized in that a predetermined gas having a low ionization voltage is introduced, and a discharge vessel in which a plasma-generating gas is introduced into a depressurized interior to form plasma, and a microwave guide of the discharge vessel. Microwave plasma having a waveguide with one end attached to the inlet for introducing microwaves into the discharge vessel, and magnetic field forming means for forming a magnetic field inside the discharge vessel In the production apparatus, the waveguide has a positive potential with respect to the discharge vessel, and a predetermined gas having a lower ionization voltage than the plasma-producing gas is introduced into the discharge vessel. Yes, and
The predetermined gas is an alkali metal, further characterized in that the predetermined gas is cesium, further, the plasma generation gas is hydrogen or deuterium, the predetermined gas is cesium It is characterized by having done.

[0022]

In the microwave plasma generator configured as described above, the predetermined gas whose ionization voltage is lower than that of the plasma generating gas is introduced into the discharge vessel into which the plasma generating gas is introduced. Therefore, when the microwave is introduced to start the discharge, first, the predetermined gas having a low ionization voltage starts to be ionized, and the discharge of the plasma generating gas is sequentially started. Also, microwaves are easily absorbed by ionization of gas, microwaves are not reflected, and microwaves of high power can be efficiently introduced, so that high-density plasma and large-area plasma can be generated in the discharge vessel. Can be generated.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. First, an ion source, which is one of the microwave plasma generators of the first embodiment, will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic sectional view of an ion source, FIG. 2 is a characteristic diagram of reflected power, and FIG. 3 is a characteristic diagram of extracted ion current density.

In FIG. 1, the discharge vessel 31 has a lower opening 33 having a flange 32 on the outer periphery of the lower end thereof and an upper opening 35 having a flange 34 on the outer periphery of the upper end thereof. It is a substantially cylindrical container having a length of 15 cm. The upper opening 35 is airtightly attached to the upper surface of the flange 34 via an insulator 36 made of alumina ceramic or the like to be closed, whereby the discharge vessel 31 and the upper plate 37 are closed.
And are electrically isolated.

The inside of the discharge vessel 31 is depressurized to, for example, 0.1 Pa level by an exhaust device (not shown), and the predetermined pressure is maintained. A plasma generating gas source 38 is connected to the discharge vessel 31 via an introduction pipe 40 having a leak valve 39 for adjusting the flow rate in the middle thereof. The gas introduction port 41 of the introduction pipe 40 is opened in the discharge vessel 31, and the plasma generation gas such as hydrogen or deuterium whose flow rate is adjusted is supplied from the gas introduction port 41 into the discharge vessel 31. .

Further, the discharge vessel 31 includes a predetermined gas source 4
2 is connected via an introduction pipe 44 having a leak valve 43 for adjusting the flow rate in the middle thereof. The predetermined gas source 42 is an oven or the like containing metal cesium, and the inside of the oven is heated to 300 to 350 ° C. by a heater to vaporize the metal cesium contained and generate cesium gas. There is. Further, the gas introduction port 45 of the introduction pipe 44 is opened in the discharge vessel 31, and the cesium gas which is a predetermined gas whose flow rate is adjusted is supplied from the gas introduction port 45 into the discharge vessel 31.

Further, in the upper plate 37, a microwave introduction port 46 is provided at a central portion of the upper plate 37, and one end portion 48 of the waveguide 47 is provided in the discharge vessel 3.
It is formed by attaching so as to open into the inside of the waveguide 1. On the other hand, the other end of the waveguide 47 is, for example, 2.45G.
It is connected to a microwave source (not shown) that generates a microwave of Hz. The microwave propagates from the microwave source into the waveguide 47, passes through the microwave introduction port 46, and is introduced into the discharge vessel 31.

Further, the waveguide 47 is provided with a bent portion 49 for bending the microwave transmission path at a substantially right angle on one end side of the intermediate portion, and is directly viewed from the microwave introduction port 46 on the other end side of the bent portion 49. Vacuum window 5 made of a material that is transparent to microwaves, for example, alumina ceramic, at a position where it is not possible
0 is installed. The main surface of the vacuum window 50 is the waveguide 4
The waveguide 47 is installed so as to intersect with the microwave transmission path 7, and the one end 48 side and the other end side of the waveguide 47 are hermetically separated.

The waveguide 47, which is electrically insulated from the discharge vessel 31 by the insulating member 36, is 0-10.
It is connected to a DC power source 51 which is variable to 0V through a switch 52, and a positive potential is applied to the discharge vessel 31 by closing the switch 52.

Further, the lower opening 33 of the discharge vessel 31 is closed by attaching an inner lead electrode 55 of the electrode portion 54 so that an insulating ring 53 is interposed between the lower opening 33 and the flange 32. The electrode portion 54 is composed of a plurality of extraction electrodes 56 and an insulating ring 57 provided between the electrodes, in addition to the inner extraction electrode 55 facing the discharge vessel 31. In each of the extraction electrodes 55 and 56, a plurality of through holes 58 through which ions are extracted are formed in the central portion so that the direction parallel to the axis of the discharge vessel 31 is the ion extraction direction.

Then, each extraction electrode 55 of the electrode portion 54,
56 is connected to a corresponding terminal of the acceleration power supply 59, and a predetermined voltage is applied to each discharge vessel 31 so that an ion beam can be extracted from the plasma generated inside the discharge vessel 31.

On the other hand, on the outer wall surface of the cylindrical portion of the discharge vessel 31, there are provided two annular permanent magnets 60 and 61, which are SmCo serving as a magnetic field forming means, one of which is an upper end closed by the upper plate 37. Near the flange 34 of the other flange 32 at the other end
In the vicinity, the annular surfaces are made horizontal, and they are arranged at intervals of about 9.2 cm in the vertical direction.

The pair of permanent magnets 60 and 61 are magnetized in opposite radial directions, and the upper permanent magnet 60 has an N pole on the inner diameter side and an S pole on the outer diameter side, and a lower permanent magnet 61. Has an S pole on the inner diameter side and an N pole on the outer diameter side. Therefore, the magnetic field lines 62 are formed in the discharge vessel 31 by the permanent magnets 60 and 61 so as to largely project in the central axis direction of the discharge vessel 31.

With this structure, the inside of the discharge vessel 31 is depressurized to a predetermined pressure on the order of 0.1 Pa by an exhaust device (not shown), and while maintaining this state, the gas is introduced from the gas inlet 41. Hydrogen gas or deuterium, which is a plasma generation gas, is introduced from the plasma generation gas source 38. In addition, the cesium gas as the predetermined gas from the gas introduction port 45 is opened in the discharge vessel 31 for a short time by opening the leak valve 43 for adjusting the flow rate, so that only a quantity corresponding to the flow rate of the plasma generating gas, etc. Predetermined gas source 4
Introduced from 2.

Then, after the inside of the discharge vessel 31 is made into a predetermined gas atmosphere by the plasma generating gas and the predetermined gas introduced in a small amount so as to be added thereto, the inside of the waveguide 47 is supplied from a microwave generation source (not shown). , The microwave of 2.45 GHz transmitted through the vacuum window 50 on the way,
It is introduced into the discharge vessel 31 through the microwave introduction port 46.

As a result, the microwave electric field accelerates the electrons to high energy, and discharge plasma is generated in the discharge vessel 31. Then, H ⁻ or D ⁻ is generated from the excited hydrogen molecule or deuterium molecule, and the generated H ⁻ or D ^{−
The −} is accelerated while passing through the through hole 58 so as to have a predetermined energy by the extraction electrodes 55 and 56 of the electrode portion 54 to which a predetermined voltage is applied, and is extracted to the outside as an H ⁻ beam or a D ⁻ beam. .

At this time, as described above, inside the one end portion 48 of the waveguide 47, the microwave introduction port 4 is provided up to the vacuum window 50.
6 through which the same gas atmosphere as in the discharge vessel 31 is provided, and the waveguide 4 is provided in the vicinity of the microwave inlet 46.
7 and the upper plate 37 are in a state of being electrically insulated from the discharge vessel 31, and by closing the switch 52, a positive potential is applied. When the waveguide 47 and the upper plate 37 have a positive potential, the plasma and the inner wall of the discharge vessel 31,
The starting position of the plasma sheath formed between the lower surface of the upper plate 37 and the waveguide 47 is farther from the inner wall of the discharge vessel 31 with respect to the lower surface of the upper plate 37, and the microwave guiding is performed. The inlet 46 is not shaped so as to enter the one end portion 48 of the waveguide 47.

For the microwave introduced from the waveguide 47 into the discharge vessel 31 by using, for example, hydrogen gas as plasma generating gas, the potential V _CW of the waveguide 47 is plotted on the horizontal axis and the incident power P _{I is} plotted on the vertical axis. Of the reflected power P _R to (P _R
/ P _I ) as shown in the characteristic diagram of FIG. Figure 2
Is when the pressure in the discharge vessel 31 is 0.3 Pa, the voltage V _PC of the inner extraction electrode 55 is 45 V, and the incident power from the waveguide 47 is 4 kW. The characteristic curve X including the white circle points is cesium. A case where gas is not introduced is shown, and a characteristic curve Y including black dots shows a case where cesium gas is introduced.

These characteristic curves X and Y show that the ratio (P) of both powers increases as the positive potential V _CW of the waveguide 47 increases.
_R / P _I ), that is, the incident power P _I is constant, the reflected power P _R decreases, but when the cesium gas is not introduced, as shown in the characteristic curve X, the waveguide 47
Although the reflected power P _R tends to decrease slightly until the potential V _CW of V reaches about 35 V, 70% of the reflected power P _R is reflected. Then, when the potential V _CW is further increased, it rapidly decreases until it becomes approximately 55 V, and thereafter, even if the potential V _CW is further increased, the ratio (P _R / P _I ) of both powers hardly decreases and the incident power P 30% of _I will be reflected.

On the other hand, in the case of introducing cesium gas, as shown by the characteristic curve Y, the reflected power P _R is
The electric potential V _CW of the electric field decreases sharply as the electric potential V _CW of the electric field increases, and at about 40 V, the reflection power P _R becomes almost zero and is close to non-reflection. Thereby, the incident power P _I introduced through the waveguide 47
Is almost the input power P _N.

This is because the ionization voltage of cesium is the ionization voltage of hydrogen (H; 13.6 V, H ₂ ;
3.89 V, which is lower than 15.4 V), and therefore cesium is ionized by applying energy lower than that of hydrogen, and a higher density plasma can be obtained for the same input power P _N. . Further, when there is a magnetic field, the higher the plasma density, the more the microwave is absorbed by the plasma. Increased absorption further increases plasma density.

Then, as shown in FIG. 3, in which the horizontal axis represents the input power P _N , that is, the difference between the incident power P _I and the reflected power P _R , and the vertical axis represents the extracted ion current density D _I , the cesium gas Without introduction, as can be seen in the characteristic curve Q including the points with white circles, the extraction current density D _I was also about 3.5 mA / cm ² until the input power P _N was about 2.5 kW.
When the input power P _N exceeds about 2.5 kW, the increasing tendency of the extraction current density D _I becomes smaller.

On the other hand, when the cesium gas is introduced, as shown in the characteristic curve R including the black dots, the extraction current density D _I also increases as the input power P _N increases as compared with the case where the cesium gas is not introduced. Both increase, and the extraction current density D _I becomes larger than the case where the cesium gas is not introduced even at the same input power P _N.

As described above, by introducing a small amount of cesium gas having a lower ionization voltage than hydrogen gas into the hydrogen gas of the plasma generating gas introduced into the discharge vessel 31 constituting the ion source, First, the introduced microwave causes ionization of cesium, which is easily ionized, and chain ionization of hydrogen gas.

Further, this ionization facilitates absorption of microwaves and eliminates reflection, so that attenuation due to reflection is eliminated. Then, the microwave with high power can be efficiently introduced into the discharge vessel 31 by the waveguide 47, and high-density plasma or large-area plasma can be generated in the discharge vessel 31. Moreover, an ion beam having a larger current value can be extracted from the electrode portion 54.

In the above description, hydrogen or deuterium is taken as the plasma generating gas, and cesium, which has the lowest ionization voltage and which is the most ionizable among the elements, is introduced as the predetermined gas. However, the predetermined gas is not limited to this, as long as the predetermined gas has an ionization voltage lower than that of the plasma-generating gas, and may be an alkali metal such as lithium, sodium, or potassium, or xenon when the plasma-generating gas is hydrogen. May be.

Further, as a combination of the plasma generating gas and the predetermined gas, argon or xenon for oxygen or nitrogen and cesium for chlorine can be used to obtain the same effect.

Next, a plasma source which is one of the microwave plasma generators of the second embodiment will be described with reference to FIG. FIG. 4 is a schematic sectional view of the plasma source.

In FIG. 4, the discharge vessel 65 is a substantially cylindrical vessel, and the upper portion thereof is hermetically closed by the upper plate 37. A plasma generation gas source 38 is connected to the discharge vessel 65 by an introduction pipe 40 having a leak valve 39 for adjusting a flow rate in the middle thereof, and hydrogen or the like which is a plasma generation gas is supplied into the discharge vessel 65. It is like this. Further, a predetermined gas source 42 is connected to the discharge vessel 65 by an introduction pipe 44 provided with a leak valve 43 for adjusting the flow rate in the middle part thereof, so that the cesium gas which is a predetermined gas is supplied into the discharge vessel 65. It has become.

A waveguide 47 is attached to the central portion of the upper plate 37 so as to open inside the discharge vessel 65. The waveguide 47 is 0 to 100 relative to the discharge vessel 65.
A positive potential is applied to the V by the variable DC power supply 51.

Further, on the outer wall surface of the discharge vessel 65, annular permanent magnets 60, 61 of magnetic field forming means are arranged at intervals vertically in the axial direction.

On the other hand, in the lower opening 33 of the discharge vessel 65, the processing vessel 66 is hermetically attached by interposing the insulating ring 53 between the upper flange 67 and the flange 32 of the discharge vessel 65. The processing container 66 is provided with a mounting table 69 for mounting the processing sample 68 on the inner bottom thereof.
Further, an exhaust port 70 is formed in the lower part, and the inside of the discharge container 65 and the processing container 66 is decompressed by an exhaust device (not shown) connected to the exhaust port 70, so that a predetermined pressure is maintained.

With the above-described structure, after the processing sample 68 is placed on the mounting table 69 in the processing container 66, the inside of the discharge container 65 is depressurized and plasma is generated in the depressurized discharge container 65. Hydrogen gas as a gas and cesium gas as a predetermined gas are introduced to obtain a predetermined atmosphere. Then, microwaves are introduced into the discharge vessel 65 from a microwave generation source (not shown) through the waveguide 47.

By the introduction of this microwave, electrons are accelerated to high energy by the microwave electric field, and discharge plasma is generated in the discharge container 65 and the processing container 66. Then, by irradiating the exposed portion of the processed sample 68 placed in the processing container 66 with this discharge plasma, the plasma processing of the processed sample 68 is executed.

At this time, also in the present embodiment, as in the first embodiment, by setting the positive potential applied to the waveguide 47 as appropriate, the ion sheath is inserted even inside the waveguide 47. It doesn't belong. Further, the cesium gas having a lower ionization voltage than the introduced hydrogen gas is first ionized, whereby the microwave is introduced into the discharge vessel 65 with almost no attenuation due to reflection, and the input power is It is almost equal to the incident power.

As a result, in the present embodiment also, microwaves of high power can be efficiently introduced into the discharge vessel 65, and high-density plasma, large-area plasma, etc. can be generated in the discharge vessel 65.

The present invention is not limited to the above embodiments of the ion source and the plasma source, and a microwave plasma generator such as a semiconductor manufacturing apparatus or a chemical processing apparatus using the discharge plasma by microwaves. Applied to.

[0058]

As is apparent from the above description, the present invention is configured so that a predetermined gas having a lower ionization voltage than that of the plasma generating gas is added to the plasma generating gas. Can be efficiently introduced, and high density plasma and large area plasma can be generated in the discharge vessel.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a first embodiment according to a microwave plasma generator of the present invention.

FIG. 2 is a characteristic diagram of reflected power in the first embodiment of the present invention.

FIG. 3 is a characteristic diagram of extraction ion current density in the first embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a schematic configuration of a second embodiment according to the microwave plasma generator of the present invention.

FIG. 5 is a sectional view showing a schematic configuration of an ion source according to a conventional microwave plasma generation device.

6 is a cross-sectional view showing an enlarged main part of FIG.

FIG. 7 is a cross-sectional view showing a schematic configuration of a microwave plasma generation device of a comparative example.

FIG. 8 is a cross-sectional view showing an enlarged main part of FIG.

[Explanation of symbols]

 31 ... Discharge container 38 ... Plasma generating gas source 42 ... Predetermined gas source 46 ... Microwave inlet 47 ... Waveguide 51 ... DC power supply 60, 61 ... Permanent magnet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/30 21/3065

Claims (5)

[Claims] 1. A discharge vessel in which a plasma-generating gas is introduced into a depressurized interior to form plasma, and one end is attached to a microwave introduction port of the discharge vessel to introduce microwaves into the discharge vessel. In a microwave plasma generator including a waveguide and a magnetic field forming means for forming a magnetic field inside the discharge vessel, a predetermined gas having an ionization voltage lower than that of the plasma generating gas is introduced into the discharge vessel. A microwave plasma generator characterized in that. 2. A discharge vessel in which plasma-generating gas is introduced into a depressurized interior to form plasma, and one end is attached to a microwave introduction port of the discharge vessel to introduce microwaves into the discharge vessel. A microwave plasma generator comprising a waveguide and a magnetic field forming means for forming a magnetic field inside the discharge vessel, wherein the waveguide has a positive potential with respect to the discharge vessel, and the discharge A microwave plasma generator characterized in that a predetermined gas having a lower ionization voltage than the plasma generating gas is introduced into the container. 3. The microwave plasma generator according to claim 1, wherein the predetermined gas is an alkali metal. 4. The microwave plasma generator according to claim 1, wherein the predetermined gas is cesium. 5. The microwave plasma generator according to claim 1, wherein the plasma generating gas is hydrogen or deuterium, and the predetermined gas is cesium.