JP2001118698A - Method of generating surface wave excitation plasma and plasma generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an enlargement of size of surface wave excitation plasma with ease. SOLUTION: The plasma generating apparatus is equipped with a chamber 1 in which a qartz plate (dielectric plate) 4 with a vent hole 4B is so fixed as to have a small clearance between surface 4a and surface of inner wall, while an open mouth type antenna 6 is equipped along the side surface 4A of the quartz plate 4. Surface wave excitation plasma is generated by supplying microwave power in the chamber 6 from the open mouth type antenna 6 through the quartz plate 4. As the pressure at the side of surface 4a which does not generate plasma and at the side of surface 4b which generates plasma become equal owing to the vent hole 4B, not any more high pressure in the direction of thickness of the quartz plate 4 caused by the difference of air pressure but only dead load is applied. Consequentially, enlargement of surface size of plasma becomes easy by using a thinner quartz plate which is inexpensive despite its bigger surface size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for generating surface wave excited plasma and a plasma generator, and more particularly to a technique for enlarging the area of plasma.

[0002]

2. Description of the Related Art In recent years, plasma has been actively used, especially in the field of the electronics industry. Specifically, in the case of a semiconductor manufacturing process, the etching process, as well as the deposition process, the ashing process, and the surface reforming process, are made dry by using plasma. Recently, plasma is also used in large-area processing technology required for solar cells, large liquid crystal panels, and the like. In particular, in the case of the latter large-area processing technique, it is always desired to increase the area of the plasma. This is because the plasma processing area is proportional to the plasma area expansion, and if the plasma processing area per cycle increases, the number of times of processing can be reduced and cost reduction can be expected.

[0003] However, it is difficult to increase the area of a parallel plate type plasma or an electron cyclotron resonance (ECR) type plasma which is currently widely used. In the case of parallel plate type plasma, at the end of the electrode, power is difficult to transmit (weak electric field), the plasma density is low, and the uniformity is not sufficient, so the plasma area is limited to about 20 cm in diameter. . In the case of the ECR type plasma, since the area expansion involves an increase in the scale of the apparatus, the area of the plasma is also limited to a diameter of about 20 cm in consideration of a practical range of the apparatus scale.

On the other hand, there is a surface-wave-excited plasma as a type of plasma different from a parallel plate type plasma or an ECR type plasma. In the case of this surface wave excited plasma (SWP), FIG.
As shown in FIG. 2, while supplying the gas from the gas supply unit 52 to the chamber 51 and maintaining the reduced pressure atmosphere, the microwave power of the microwave power supply unit 53 is supplied from the aperture type antenna 54 to the dielectric plate (for example, a quartz plate). This is a method in which plasma is generated by supplying plasma to the chamber 51 so as to penetrate in the thickness direction, and microwaves become surface waves to quickly pass between the dielectric plate 55 and the plasma toward the plane of the plasma. Since it propagates, it can be said that the plasma is easily spread and suitable for increasing the area.
If the area of the dielectric plate 55 is increased, the area of the plasma can be increased.

[0005]

However, in the case of the above-described surface-wave-excited plasma, it is not easy to increase the area of the dielectric plate 55, and it is not easy to actually increase the area of the plasma. In the case of a conventional surface wave excited plasma, an aperture type antenna 5
4 is arranged and the airtightness in the chamber 51 is maintained by the dielectric plate 55. Therefore, a strong external force due to the difference between the atmospheric pressure and the low pressure in the chamber 51 is applied to the dielectric plate 55 in the thickness direction. As a result, the dielectric plate 55 must be thickened to increase the mechanical strength.
However, since the thick and large-area dielectric plate 55 is very expensive, it is not easy to expand the plasma area.

[0006] In view of the above circumstances, an object of the present invention is to provide a method of generating surface wave excited plasma and a plasma generator capable of easily realizing an increase in the area of surface wave excited plasma.

[0007]

According to a first aspect of the present invention, there is provided a method of generating a surface-wave-excited plasma in which a gas is introduced into a chamber and the chamber is maintained in a reduced-pressure atmosphere. In addition, in a method of generating surface-wave excited plasma by supplying microwave power through a dielectric plate, the dielectric plate is disposed in a chamber, and the microwave power is supplied from the side peripheral surface side of the dielectric plate. Supply.

In order to solve the above-mentioned problems, a plasma generating apparatus according to a second aspect of the present invention provides a plasma generating chamber, gas supply means for supplying gas to the chamber, and a reduced-pressure atmosphere in the chamber. Vacuum evacuation means, a dielectric plate disposed in the chamber, an aperture antenna disposed along a peripheral surface of the dielectric plate, and microwave power supplied to the aperture antenna. Power supply means.

According to a third aspect of the present invention, in the plasma generating apparatus according to the second aspect, a narrow space is provided between the surface of the dielectric plate on which the plasma is not formed and the inner wall surface of the chamber. In addition, a through-hole for ventilation is formed in the dielectric plate, which is provided and communicates between both surfaces of the dielectric plate on the plasma forming side and the plasma non-forming side.

According to a fourth aspect of the present invention, in the plasma generating apparatus according to the second aspect, a narrow space is provided between the surface of the dielectric plate on which the plasma is not formed and the inner wall surface of the chamber. The chamber is provided with a bypass pipe for ventilation, which communicates the space on each surface side of the dielectric plate.

According to a fifth aspect of the present invention, in the plasma generating apparatus according to the second aspect, a narrow space is provided between the surface of the dielectric plate on which the plasma is not formed and the inner wall surface of the chamber. While being installed, an inert gas is introduced into the space under reduced pressure.

Further, the invention of claim 6 provides the invention according to claims 2 to 5
The plasma generator according to any one of the above, further comprising a waveguide installed so as to surround the dielectric plate, an aperture type antenna is opened on a side of the waveguide facing the side peripheral surface of the dielectric plate. In addition, a waveguide wavelength adjusting means is attached to the waveguide.

According to a seventh aspect of the present invention, in the plasma generator according to the sixth aspect, a waveguide having a rectangular cross-sectional shape having a pair of short sides opposed to a pair of long sides opposed to the waveguide. The stub is a tube, in which an aperture type antenna is opened on the short side surface of the waveguide, and the means for adjusting the guide wavelength is a stub attached to the long side surface of the waveguide.

According to an eighth aspect of the present invention, there is provided the plasma generator according to the sixth aspect, wherein the waveguide has a rectangular cross-sectional shape having a pair of long sides facing the waveguide and a pair of short sides facing the waveguide. In the tube, the aperture type antenna is opened on the long side surface of the waveguide, and the guide wavelength adjusting means serves as a distance variable means for adjusting the interval between both short side faces.

[0015] The invention of claim 9 is the invention of claims 2 to 8
5. The plasma generator according to any one of the above, wherein the dielectric plate has a disk shape, and comprises a waveguide which is arranged in an annular shape surrounding the dielectric plate, wherein the side of the waveguide facing the dielectric plate is provided. An aperture type antenna is opened on the side facing the peripheral surface, and a linear waveguide for microwave power introduction is connected substantially along a tangent of the ring of the waveguide in the ring configuration. I have.

[0016]

The operation of the method for generating plasma excited by surface waves according to the present invention will be described. In the case where the surface wave excited plasma is generated by the method according to the first aspect of the present invention, the inside of the chamber is maintained in a reduced pressure atmosphere while introducing gas into the chamber, and the side periphery of the dielectric plate disposed in the chamber is maintained. Microwave power is supplied from the surface side. Then, the microwave supplied into the chamber steadily becomes a surface wave and propagates between the dielectric plate and the plasma toward the surface direction of the plasma. The region of the plasma density quickly spreads in the plane direction of the plasma, and the surface wave excited plasma having a large area is generated.

In the case of the method of the present invention, since the microwave power is supplied from the side peripheral surface of the dielectric plate disposed in the chamber, the aperture type antenna is connected to the outside of the dielectric plate as in the prior art. It is not necessary to install on the front side. As a result, it is possible to prevent a large external force from being applied in the thickness direction due to a pressure difference between the air and the reduced-pressure atmosphere between both surfaces of the dielectric plate. As a result, the dielectric plate does not need to be as thick as in the prior art, but can be a thin plate. Further, the power supply system of the present invention for supplying microwave power from the side peripheral surface of the dielectric plate can be easily realized by moving the position of the aperture antenna from the surface of the dielectric plate to the side surface.

In the case of the plasma generating apparatus according to the second aspect, the surface wave excited plasma can be generated by implementing the method according to the first aspect of the present invention.

According to the third aspect of the present invention, the pressure (atmospheric pressure) applied to both the plasma forming side and the plasma non-forming side of the dielectric plate by the ventilation through holes formed in the dielectric plate itself is equal. Thus, the force applied in the thickness direction of the dielectric plate is only due to its own weight.

In the case of the plasma generating apparatus according to the present invention, the pressure applied to both the plasma forming side and the plasma non-forming side of the dielectric plate is equalized by the ventilation bypass pipe provided in the chamber, and the dielectric plate is formed. The force applied in the thickness direction is only due to its own weight.

In the plasma generating apparatus according to the fifth aspect, since the space on the non-plasma forming surface side of the dielectric plate is reduced in pressure, the pressure difference between both surfaces of the dielectric plate is reduced. Further, since the inert gas is introduced into the space, plasma is less likely to be generated in the space on the non-plasma forming surface side, and inconvenience such as power loss due to generation of plasma in this space can be avoided. .

In the case of the plasma generating apparatus of the present invention, the guide wavelength is adjusted by the guide wavelength adjusting means attached to the waveguide in which the aperture type antenna is formed so that the desired mode microwave power can be obtained. Improve connectivity.

In the case of the plasma generating apparatus of the present invention, the stub attached to the long side surface of the waveguide having the aperture type antenna opened on the short side surface provides the coupling with the microwave power in the desired mode. Adjust the guide wavelength to get better.

In the case of the plasma generating apparatus of the present invention, the coupling with the microwave power in a desired mode is performed by a distance varying means for changing the interval between the short sides of the waveguide having the open-type antenna on the long side. The guide wavelength is adjusted by changing the distance between the short sides to improve the performance.

[0025] In the case of the plasma generating apparatus according to the ninth aspect, the linear waveguide for introducing microwave power is arranged so as to be substantially along the tangent of the annular waveguide of the annular configuration having the aperture type antenna. In connection, microwave power is transmitted from the linear waveguide to the waveguide with the aperture antenna without disturbing the distribution.

[0026]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the plasma generator of the first embodiment, FIG. 2 is a schematic cross-sectional view showing the main configuration of the plasma generator of the first embodiment, and FIG. It is a top view which shows a principal part structure.
The plasma generator of FIG. 1 is configured to generate plasma by an example of the method of generating surface wave excited plasma of the present invention. Hereinafter, the configuration of the plasma generating apparatus of the first embodiment will be described, and then the generation of the surface wave excited plasma by the apparatus of the first embodiment will be described.

The plasma generating apparatus shown in FIG. 1 has an inner diameter of about 30 c having a generation space S where a surface wave excited plasma is formed.
m, a cylindrical chamber 1, a microwave power output unit 2 for outputting microwave power as plasma generation energy, a gas supply unit 3 for supplying necessary gas into the chamber 1, and a gas supply unit 3 provided in the chamber 1. The dielectric plate is, for example, a quartz plate 4, an annular microwave waveguide 5 disposed so as to surround the peripheral side surface 4 </ b> A of the quartz plate 4, and the peripheral side surface 4 </ b> A of the quartz plate 4. And an aperture type antenna 6 provided on the side of the waveguide 5. A required gas is introduced into the chamber 1 from the gas supply unit 3, and the microwave is transmitted from the aperture type antenna 6 through the quartz plate 4. When power is supplied, a surface wave excited plasma is generated in the generation space S. Hereinafter, the configuration of each part of the plasma generator of FIG. 1 will be described more specifically.

An exhaust pipe 1C is connected to the bottom surface 1B of the chamber 1, and the chamber 1 is evacuated by a vacuum exhaust mechanism (not shown) disposed downstream of the exhaust pipe 1C. . A vacuum measuring device 7 for measuring the indoor pressure (degree of vacuum) of the chamber 1 is provided on the side of the chamber 1. Furthermore, chamber 1
In addition to the stage ST on which the workpiece W is placed, a mechanism (not shown) required for loading and unloading the workpiece W is provided.

The microwave power output unit 2 includes a high-voltage power supply 2A
And a microwave oscillator 2B, and are configured to output microwave power of 2.45 GHz. The gas supply unit 3 includes a gas source 3A for introducing a reactive main gas (a rare gas group gas such as oxygen or Ar gas or CF ₄ ) into the chamber 1 and a mass flow FA for adjusting the amount of introduction. Have. In addition, in the case of the plasma generator of FIG. 1, while introducing gas by the gas supply unit 3, the inside of the chamber 1 is usually 1 mm Torr to 1 Torr (1
(rr ≒ 133 Pa).

The quartz plate 4 provided in the chamber 1
Is a disk having a thickness of about 5 to 20 mm. The quartz plate 4
The front and back surfaces are in the chamber 1 (that is, in a reduced pressure atmosphere), and only the side peripheral surface 4A is the side wall surface 1 of the chamber 1.
The gasket G is provided so as to be exposed at an upper portion of the W and maintain a vacuum. The quartz plate 4 has a high heat-resistant temperature and a low dielectric loss, and is suitable for supplying microwave power. Further, as shown in FIG. 2, between the non-plasma-forming side surface 4 a of the quartz plate 4 and the inner surface (inner wall surface) of the upper wall 1 </ b> A also serving as a lid of the chamber 1, the width is so small that no plasma is generated. Space is provided. The quartz plate 4 has a plasma non-forming side surface 4a and a plasma forming side surface 4a.
A ventilation through-hole 4B is formed to communicate between b. As a result, the air pressure applied to both surfaces 4a and 4b of the quartz plate 4 becomes the same, and a strong force due to a pressure difference unlike the related art is not applied in the thickness direction of the quartz plate 4 to the extent that a force due to its own weight is applied. The number of the through holes 4B for ventilation is, for example, about 3 with a diameter of 6 mm, but may be one.

As shown in FIG. 2, the waveguide 5 has a pair of short sides (H) opposed to a pair of long sides 5A and 5B.
Surface) 5a, 5b, which is a flat annular waveguide having a rectangular cross section, and the short side surface (E surface) 5b inside the waveguide 5 is entirely open along the inner circumferential direction, A (complete) aperture antenna 6 is provided. However, the aperture antenna 6
Need not necessarily have a configuration that continues without interruption along the circumferential direction of the quartz plate 4. For example, the short side surface 5b of the waveguide 5 is only partially opened vertically or horizontally by a predetermined dimension at an appropriate interval along the inner circumferential direction, and is interrupted along the circumferential direction of the quartz plate 4. A so-called slot type aperture antenna may be used.

The upper long side surface 5A of the waveguide 5 has
As shown in FIG. 2, a screw type stub SB for adjusting the guide wavelength.
Are arranged at equal intervals along the circumferential direction. In the case of the embodiment, six stubs SB are provided. The stub SB attached to the long side surface 5A of the waveguide 5 adjusts the guide wavelength to improve the coupling with the microwave power of the desired mode, and can efficiently generate uniform plasma.

Further, a linear waveguide 11 for introducing microwave power is connected to the waveguide 5 arranged in an annular shape. As shown in FIG. 3, the linear waveguide 11 substantially follows the tangent of the ring of the annular waveguide 5 (a shape similar to the numeral “6” when viewed from above). ), The microwave power is transmitted from the linear waveguide 11 to the waveguide 5 having the aperture antenna 6 without disturbing the distribution. If the linear waveguide 11 is connected to the center of the annular waveguide 5 as shown by the dashed line A in FIG. 3, the distribution of microwave power is disturbed. As a result, microwave power is not successfully transmitted from the linear waveguide 11 to the waveguide 5.

As shown in FIG. 1, the microwave power transmitted from the microwave power output unit 2 passes through an isolator 8 and then passes through a directional coupler 9 from an EH type matching machine 10 to form a linear waveguide. It is configured to reach the waveguide 5 via the tube 11. In the case of the first embodiment, the amount of the supplied microwave power varies depending on various conditions such as the pressure, the type of gas, and the processing target and purpose.
It is about kW.

Next, a description will be given of how the plasma generating apparatus of the first embodiment having the above-described configuration generates surface wave excited plasma by an example of the method of the present invention. First, while exhausting the inside of the chamber 1, oxygen gas was introduced from the gas supply unit 3 so that the inside of the chamber 1 was kept at a reduced pressure atmosphere of about 1 Torr. And the microwave power output unit 2
1.5k microwave power with frequency 2.45GHz
W was output in the amount of W. Then, a large-area surface-wave-excited plasma was generated in the generation space S of the chamber 1 in a uniform state, and the workpiece W on the stage ST was processed.

The horizontal cross section of the surface wave excited plasma has a diameter of about 3
Because of the circular shape of 0 cm, the generated surface wave excited plasma is also a large-area plasma having a diameter of about 30 cm. FIG.
As shown in FIG. 5, the state of the electric field intensity near the quartz plate 4 is such that the plasma forming side surface 4b of the quartz plate 4, which is the central region of the introduction of the microwave power from the aperture antenna 6, is the strongest, and is more efficient than the conventional case. It is expected that plasma can be generated with good uniformity.

As described above, in the case of the plasma generator of the first embodiment, the pressure applied to both surfaces 4a and 4b of the quartz plate 4 is equal, and no external force due to the pressure difference is applied in the thickness direction of the quartz plate 4. It is sufficient that the quartz plate 4 is thin enough to withstand its own weight. Since the thickness of the quartz plate 4 proportionally affects the price, the cost reduction effect of reducing the thickness is remarkable. The quartz plate 4 is approximately 20 cm to 40 cm.
cm, usually about 30 cm in diameter, conventionally 20 m
Although a thickness of m was required, in the case of the present invention, about 5 mm is sufficient irrespective of the diameter.

Depending on the type of plasma treatment, the quartz plate 4
The quartz plate 4 is liable to be damaged and the quartz plate 4 must be frequently replaced with a new one. When the quartz plate 4 is used as a consumable item, the quartz plate 4 is inexpensive and the present invention is very effective. It is. In addition, a power supply system for supplying microwave power from the side peripheral surface side of the quartz plate 4 can be easily realized by moving the antenna from the surface of the quartz plate 4 to the side surface. Therefore, in the case of the present invention, the area of the surface wave excited plasma can be easily increased without any difficulty.

Next, a second embodiment of the present invention will be described.
FIG. 5 is a schematic cross-sectional view showing a main part configuration of the plasma generator of the second embodiment, and FIG. 6 is a plan view showing a main part configuration of the apparatus of the second embodiment. In the case of the apparatus of the second embodiment, instead of the through hole 4B for ventilation being formed in the quartz plate 4, a ventilation bypass conduit for communicating the space on both sides 4a and 4b of the quartz plate 4 with the chamber 1 is provided. Except that 12 is attached, it is completely the same as the first embodiment, and only the differences will be described.
The description of the same points is omitted. In the case of the plasma generator of the second embodiment, both surfaces 4a, 4b of the quartz plate 4 on the non-plasma forming side and the plasma forming side are formed by the ventilation bypass pipe 12.
In the thickness direction of the quartz plate 4, no external force is applied except for the force of its own weight, and the quartz plate 4 is sufficient to be thin enough to withstand its own weight. 3 and 6
, The stub SB is not shown.

Next, a third embodiment of the present invention will be described. FIG. 7 is a schematic cross-sectional view showing a main part configuration of the plasma generator of the third embodiment, and FIG. 8 is a plan view showing a main part configuration of the plasma generator of the third embodiment. In the case of the device of the third embodiment, as shown in FIG. 7, the waveguide 13 has a pair of long sides 13A and 13B facing each other and a pair of short sides 13a and 13b facing each other.
In addition to the tubular annular waveguide having a rectangular cross section having the following configuration, the lower short side surface 13b is configured to be able to reciprocate entirely in the direction of the upper short side surface 13a,
The wavelength λg of the incident microwave on the connection side of the linear waveguide 14
Is exactly the same as the first embodiment except that the tube is slightly expanded by the length of, so only the differences will be described, and the description of the same points will be omitted.

In the plasma device of the third embodiment, the short side surface 1
The front end of the short side drive shaft 15 is fixed to the lower surface of the lower side 3b, and the distance between the two short side surfaces 13a and 13b changes as the drive shaft 15 using an air cylinder or the like moves in the direction of the arrow. Thus, the sectional area of the waveguide 13 is changed. Therefore, by appropriately adjusting the interval between the short side surfaces 13a and 13b, it is possible to improve the coupling with the microwave power in the desired mode. The aperture antenna 6 is formed by opening the long side surface 13B of the waveguide 13 in the circumferential direction.

The present invention is not limited to the above embodiment, but can be modified as follows. (1) In the case of the above embodiment, the microwave waveguide having the quartz plate for the chamber and the dielectric plate and the aperture type antenna had a circular configuration. However, as shown in FIG. A modified example is a device in which a quartz plate 17 for a plate and a microwave waveguide 18 having an aperture type antenna have a rectangular configuration.

(2) In the case of the above embodiment, one side of the microwave waveguide is completely opened to form an aperture type antenna. However, as shown in FIG. The opening antenna 20 may be formed such that both ends of one side are left.

(3) In the case of the above embodiment, a narrow space is provided between the non-plasma forming side surface of the quartz plate for the dielectric plate and the inner wall surface of the chamber. As shown in FIG. 11, a quartz plate 2 for a dielectric plate
As a modified example, an apparatus in which the first non-plasma-forming side surface 21a is bonded to the inner wall surface of the chamber 1 with an adhesive BD or the like so that there is no gap.

(4) In the embodiment, the dielectric plate is a quartz plate, but may be an alumina plate or an aluminum nitride plate.

(5) In the case of the embodiment, the means for adjusting the guide wavelength is a screw type stub or a distance variable mechanism for adjusting the interval between both short side surfaces of the waveguide. An apparatus having a structure in which the means is a branch pipe is a modified example.

(6) In the embodiment shown in FIGS. 1 and 5, in order to make the pressure acting on the plasma non-forming surface of the dielectric plate equal to the pressure in the chamber, the through holes for ventilation are formed in the dielectric plate. Was opened or a bypass line for ventilation was provided. However, with this configuration, depending on the type of gas used, gas pressure, microwave power, etc., there is a concern that plasma may be lit not only on the plasma forming side surface of the dielectric plate but also on the plasma non-forming side surface. Is done. When plasma is lit on the surface on the side where no plasma is formed, power loss increases, which is inconvenient. Therefore, do not provide a ventilation through hole or ventilation bypass line,
You may comprise as follows.

That is, in a narrow space between the surface of the dielectric plate on the side where the plasma is not formed and the inner wall surface of the chamber,
Separately from the introduction of the gas to the plasma forming surface side (inside of the chamber), an inert gas (for example, nitrogen gas) that is difficult to generate plasma is introduced, and the space is maintained at a reduced pressure of 50 to 300 Torr, preferably about 100 Torr. . With this configuration, generation of plasma on the non-plasma forming surface side can be suppressed. In this case, a pressure difference is generated between both surfaces of the dielectric plate, but the pressure difference is smaller than that of the conventional device in which the atmospheric pressure acts on the non-plasma forming surface side. Can be thin.

The reason why the pressure in the space is higher than the pressure in the chamber (normally, 1 mm Torr to 1 Torr) is that plasma is less likely to be generated as the pressure in the space is higher. Therefore, it is possible to sufficiently suppress the generation of plasma simply by introducing a nitrogen gas or the like which is difficult to turn into plasma into the space, and when the pressure in the space does not need to be increased, the pressure in the space is reduced to a level close to the inside of the chamber. May be. As a result, the thickness of the dielectric plate can be reduced to a level equivalent to that of the embodiment shown in FIGS. However, in this case, when the chamber is opened, atmospheric pressure acts on the plasma forming surface side of the dielectric plate, and the pressure difference between both surfaces of the dielectric plate increases, so that the pressure on both surfaces of the dielectric plate increases. It is preferable to configure so as to change in conjunction. As such a configuration example, a method of providing a leak valve that connects the space and the atmosphere, and operating the leak valve in conjunction with the opening operation of the chamber to return the pressure of the space to the atmospheric pressure, or A method of changing the pressure of the introduced nitrogen gas or the like in conjunction with the pressure in the chamber can be employed.

[0050]

As described in detail above, according to the method of generating surface-wave-excited plasma according to the first aspect of the present invention, microwave power is supplied from the side peripheral surface side of the dielectric plate provided in the chamber. Because of the supply configuration, it is possible to avoid applying a large external force due to the pressure difference between the atmosphere and the decompressed atmosphere in the thickness direction of the dielectric plate as in the related art.As a result, the dielectric plate is a thin and inexpensive plate even if the area is large. That's enough. In addition, a power supply method for supplying microwave power from the side peripheral surface of the dielectric plate can be easily realized by moving the position of the aperture antenna from the surface of the dielectric plate toward the side surface. Therefore, according to the method of the present invention, the area of the surface wave excited plasma can be easily enlarged.

Further, according to the plasma generating apparatus of the second aspect of the present invention, by performing the method of the first aspect of the present invention, it is possible to generate a surface wave excited plasma, so that a thin and inexpensive large area can be obtained. The area of the surface-wave-excited plasma can be easily expanded by using the dielectric plate described above.

According to the third aspect of the present invention, the pressure applied to both the plasma forming side and the plasma non-forming side of the dielectric plate by the ventilation through holes formed in the dielectric plate itself. Are equal, and the force applied in the thickness direction of the dielectric plate is only due to its own weight. Therefore, the dielectric plate may be a very thin plate that supports its own weight.

According to the fourth aspect of the present invention, the pressure applied to both the plasma forming side and the plasma non-forming side of the dielectric plate by the ventilation bypass pipe provided in the chamber is equal. Since the force applied in the thickness direction of the dielectric plate depends only on its own weight, the dielectric plate need only be a very thin plate that supports its own weight.

According to the plasma generating apparatus of the present invention, since the space on the non-plasma forming surface side of the dielectric plate is reduced in pressure, the pressure difference between both surfaces of the dielectric plate is reduced, and The thickness of the plate can be reduced. Further, since the inert gas is introduced into the space, plasma is less likely to be generated in the space on the non-plasma forming surface side, and inconvenience such as power loss due to generation of plasma in this space can be avoided. .

According to the plasma generating apparatus of the present invention, the guide wavelength is adjusted by the guide wavelength adjusting means attached to the waveguide in which the aperture type antenna is formed. Since the configuration can improve the coupling with electric power, surface wave excited plasma can be generated uniformly and efficiently.

According to the plasma generator of the present invention, since the stub for adjusting the guide wavelength is provided in the waveguide having the aperture type antenna opened on the short side surface, the guide wavelength is adjusted by the stub. By doing so, it is possible to easily improve the coupling with the microwave power in the desired mode.

According to the eighth aspect of the present invention, there is provided a plasma generating apparatus including a wavelength varying means for adjusting a guide wavelength for changing an interval between short sides of a waveguide having an aperture type antenna formed on a long side. Therefore, by changing the interval between the short sides, it is possible to easily improve the coupling with the microwave power in the desired mode.

According to the ninth aspect of the present invention, the linear waveguide for introducing microwave power is substantially along the tangent of the annular waveguide of the annularly arranged waveguide having the aperture type antenna. With such a connection, the microwave power is successfully transmitted from the linear waveguide to the waveguide having the aperture antenna without disturbing the distribution.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a plasma generator of a first embodiment.

FIG. 2 is a schematic sectional view showing a configuration of a main part of the plasma generator of the first embodiment.

FIG. 3 is a plan view showing a configuration of a main part of the plasma generator of the first embodiment.

FIG. 4 is a graph showing an electric field intensity distribution in the vicinity of a quartz plate of the plasma generator.

FIG. 5 is a schematic sectional view showing a configuration of a main part of a plasma generator of a second embodiment.

FIG. 6 is a plan view showing a main configuration of a plasma generator of a second embodiment.

FIG. 7 is a schematic sectional view showing a configuration of a main part of a plasma generator of a third embodiment.

FIG. 8 is a plan view showing a main configuration of a plasma generator according to a third embodiment.

FIG. 9 is a plan view illustrating a configuration of a main part of a modified example device.

FIG. 10 is a schematic sectional view showing a configuration of a main part of another modified example device.

FIG. 11 is a schematic cross-sectional view illustrating a configuration of a main part of another modified example device.

FIG. 12 is a schematic cross-sectional view illustrating a main part configuration of a conventional plasma generator.

[Explanation of symbols]

 1, 16 ... chamber 2 ... microwave power output unit 3 ... gas supply unit 4, 17, 21 ... quartz plate (dielectric plate) 4A ... peripheral side surface 4B ... ventilation through hole 5, 13, 19 ... microwave waveguide 6, 20 ... aperture type antennas 4a, 21a ... plasma non-forming side surface 4b ... plasma forming side surface 5A, 5B ... long side surface 5a, 5b ... short side surface SB ... screw type stub 11, 14, ... linear waveguide 12 ... bypass passage for ventilation 13A, 13B ... long side surface 13a, 13b ... short side surface 15 ... drive shaft

Continued on the front page (72) Inventor Seiichi Takasuka 10-7 Kameicho, Takarazuka-shi, Hyogo F-term in Nissin Corporation (reference) 5F004 AA16 BA20 BB14 BB32 BC08

Claims (9)

[Claims] In a method of generating a surface wave excited plasma by supplying microwave power through a dielectric plate while maintaining a reduced pressure atmosphere in the chamber while introducing a gas into the chamber, the method includes the steps of: A method for generating surface-wave-excited plasma, which is provided in a chamber and supplies microwave power from a side peripheral surface of a dielectric plate. 2. A plasma generating chamber, gas supply means for supplying gas to the chamber, vacuum exhaust means for maintaining the inside of the chamber in a reduced pressure atmosphere, and a dielectric plate provided in the chamber; A plasma generator, comprising: an aperture antenna provided along a side peripheral surface of a dielectric plate; and power supply means for supplying microwave power to the aperture antenna. 3. The plasma generator according to claim 2, wherein a narrow space is provided between the non-plasma forming surface of the dielectric plate and the inner wall surface of the chamber, and the dielectric plate is installed. A plasma generator in which a through hole for ventilation is formed in a dielectric plate for communicating between both surfaces of a body plate on a plasma forming side and a plasma non-forming side. 4. The plasma generating apparatus according to claim 2, wherein a narrow space is provided between the non-plasma forming surface of the dielectric plate and the inner wall surface of the chamber, and the dielectric plate is installed. A plasma generator in which a ventilation bypass pipe for communicating a space on each surface side of a body plate is provided in a chamber. 5. The plasma generating apparatus according to claim 2, wherein a narrow space is provided between a non-plasma forming surface of the dielectric plate and an inner wall surface of the chamber, and the dielectric plate is provided. A plasma generator in which an inert gas is introduced into a space under reduced pressure. 6. The plasma generating apparatus according to claim 2, further comprising a waveguide installed so as to surround the dielectric plate, wherein the waveguide is provided on a side peripheral surface of the dielectric plate in the waveguide. A plasma generator in which an aperture type antenna is opened on the opposite side and a waveguide is provided with means for adjusting a guide wavelength. 7. A plasma generating apparatus according to claim 6, wherein the waveguide has a rectangular cross-sectional shape having a pair of long sides facing the waveguide and a pair of short sides facing the waveguide. A plasma generator in which an aperture type antenna is opened on a short side surface of a tube and a means for adjusting a wavelength in the tube is a stub attached to a long side surface of the waveguide. 8. The plasma generator according to claim 6, wherein the waveguide has a rectangular cross-sectional shape having a pair of long sides facing the waveguide and a pair of short sides facing the waveguide. A plasma generator in which an aperture type antenna is opened on a long side surface of a tube, and a means for adjusting a wavelength in the tube is a variable distance means for adjusting a distance between both short side surfaces. 9. The plasma generating apparatus according to claim 2, wherein the dielectric plate has a disk shape, and includes a waveguide arranged in an annular shape surrounding the dielectric plate. An aperture type antenna is opened on the side of the waveguide facing the side peripheral surface of the dielectric plate, and microwave power is introduced substantially along the tangent of the ring of the waveguide in an annular arrangement. A plasma generator to which the linear waveguides are connected.