JP3237450U - Combined plasma source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite plasma source for gas dissociation and chemical activation by constructing a composite plasma source by a mechanism in which a microwave plasma and a transformer coupled plasma are coupled. A reaction chamber 10 of a composite plasma source is composed of two microwave resonance chambers 12 and 14 and a plurality of sets of hollow metal tubes 16. A microwave resonance chamber is used to generate a high-intensity electric field to generate plasma, and then a high-efficiency coupling mechanism of transformer-coupled plasma produces high-power and high-density plasma. As a result, air conduction can be significantly improved, and the hollow metal pipes of each set are driven by the ferrite transformer core 50 of each set to disperse the power, and the energy density of each hollow metal pipe is lowered. Thus, the conversion of plasma from diffusion mode to contraction mode can be reduced, and thus the operable gas flow rate can be further increased. [Selection diagram] Fig. 2

Description

The present invention relates to a plasma source, in particular to a composite plasma source.

Plasma is widely used in semiconductor processes and other industrial manufacturing, and its advantages are that it can decompose gas molecules, generate neutral radicals, ions, atoms, and electrons, and in molecules. The point is to excite the constituent highly reactive mixtures to provide the various physical and chemical reactions required for the process.
There are many conventional mechanisms for generating plasma, one of which is to generate an inductance coupled plasma discharge using a ferrite transformer core. Its main mechanism, as shown in FIG. 1, utilizes a ferrite transformer core 502 to generate an inductive electric field in a Circular Vacuum Chamber 500 to discharge a gas. The annular vacuum chamber 500 has a gas inlet 506 at one end and a gas outlet 508 at the other end. Such a scheme is similar to the transformer principle. Good coupling efficiency is formed because the power supply is connected to the primary side of the ferrite transformer core 502, the plasma is on the secondary side of the single wrap, and the magnetic fluxes are connected to each other. In the plasma, the electron drift current is driven by an induced electric field and flows along the vacuum chamber 500 to form a closed path. For this reason, this mechanism is also referred to as transformer coupled plasma (TCP).
According to the prior art, by connecting the ferrite transformer core 502 to an AC power source, an induced electric field can be generated in the annular vacuum chamber 500 and a current can be excited in the plasma. The configuration requires the use of a ceramic ring 504 to form an electrical barrier zone. Otherwise, the ferrite transformer core 502 will be short-circuited, unable to generate an induced electric field in the annular vacuum chamber 500, and if the electrical barrier zone is not small enough, it will generate a sufficiently strong electric field strength. Therefore, the plasma cannot be stably excited and held. However, the strong electric field generated by the ferrite transformer core 502 is concentrated in the electrical barrier zone composed of the ceramic ring 504 due to the influence of the metal structure of the annular vacuum chamber 500, and in some cases, the ceramic ring 504 is discharged by regional discharge. There is a problem that the ceramic bursts, the electrical barrier is destroyed, the power supply is even damaged by the reverse discharge, or the plating layer that protects the reaction chamber is detached.

Anderson described such methods in US Pat. Nos. 3,500,118 and 3,987,334, and in US Pat. No. 4,180,763, ferrite core TCP is used for lighting applications. Proposed to apply. Reinberg et al. Proposed in US Pat. No. 4,431,898 to remove photoresist by plasma in a semiconductor process. This TCP technique is used to dissociate a gas to provide a plasma source with a high activation rate. In some high-pressure, high-gas flow applications, high-power density plasmas are used to chemically activate the working gas, or to change the properties and composition of the gas to vacuum these chemically activated gases. Need to be sent to the system.
Such applications are called "remote plasma treatment", which include (1) remote cleaning of the chamber, (2) remote incineration of the polymer surface in the chamber, and (3) vacuum. Includes cleaning of the downstream foreline in the foreline and reduction of post-treatment gas. These applications involve high flow rates (greater than 1 slm) of negatively charged plasma discharge gases (eg O ₂ , NF ₃ , SF ₆ ) and higher gas pressures (greater than 1 Torr). For this reason, high power densities are required, otherwise high dissociation and activation of the working gas cannot be achieved. Under high pressure and high flow operating conditions, as with many inductance coupled plasma source devices, the strength of the inductively coupled plasma of TCP is insufficient to ignite the plasma discharge, and by other means to the vacuum reaction chamber. It is necessary to generate a high intensity electric field to ignite the plasma discharge. For example, a high voltage electrode is added, or a high AC voltage is passed through a part of an electrically insulated chamber to generate a local radio frequency glow discharge. However, this limits the life and availability of the high voltage discharger. For example, in one document, by adding a resonant circuit to a circuit to generate a high voltage (1 to 10 kV), regional discharge can be effectively generated to generate plasma, but the same after plasma is generated. There is a statement that if the use of voltage is continued, an extremely large amount of current will be generated, damaging the power element. Therefore, by adding a high-voltage relay (Relay) to the circuit, after plasma is generated, the power supply circuit is quickly converted into a non-resonant circuit, and the voltage can be dropped to avoid damage due to a large current. .. However, if the relay fails or the control signal is delayed and the relay cannot be started immediately, the power element is damaged. On the other hand, when high voltage electrodes are used, the insulating components of the vacuum chamber are easily destroyed, causing a short circuit, and the plating layer on the wall of the chamber is detached and enters the process chamber, causing contamination by particles.
In some applications, for example in the manufacture of panel displays, the volume of the process system is so large that it cannot meet the demands of the process without the use of large amounts of gas (> 30 slm). Therefore, according to the structure of the annular vacuum chamber according to the prior art, it is necessary to significantly increase the operating air pressure and the power density. However, when doing so, the diameter of the cylindrical plasma in the vacuum chamber becomes smaller due to the collision of ions and electrons, the dipolar diffusion, and the limitation of heat dissipation performance, and the plasma becomes a diffusion mode. ) Is converted to the diffusion mode, the vacuum chamber cannot be filled, and some gas cannot react with the plasma. This reduces the overall gas activation rate and makes it impossible to meet the process requirements. In severe cases, the plasma becomes unstable, unable to maintain the plasma, and even extinguish the fire. Therefore, how to improve the structure of the prior art annular vacuum chamber to ensure plasma stability is a problem that must be overcome in order to further increase the gas flow.

In order to solve the above-mentioned problems of the prior art, an object of the present invention is to improve the shortcomings of the conventional TCP plasma technique and to increase the flow rate of the working gas.
The main techniques are (1) to construct a composite plasma source by a mechanism for combining microwave plasma and TCP plasma. A microwave resonance chamber is used to generate a high-intensity electric field to generate plasma, and then TCP's highly efficient energy coupling mechanism for plasma produces high-power and high-density plasma. As a result, the shortcomings of the high voltage igniter can be solved, and since the microwave is responsible for exciting and maintaining the initial plasma, the shortcomings due to the weak electric field of TCP can be solved. The stability of the plasma can be improved.
(2) The reaction chamber is composed of two microwave resonance chambers and a plurality of sets of hollow metal tubes, and can significantly increase air conduction as compared with the annular vacuum chamber (Toroidal Vacuum Chamber) according to the prior art. When the gas flow rate is high, the gas pressure can be maintained in the range of several Torr. At the same time, the power of each set of hollow metal tubes is distributed, which reduces the energy density of each hollow metal tube, reducing the conversion of plasma from the diffusion mode to the control mode. Can be done.

A main object of the present invention is to provide a composite plasma source configured by a mechanism in which microwave plasma and TCP plasma are combined.

The next object of the present invention is to use a microwave resonance chamber to generate a high-intensity electric field to generate plasma, and then use a TCP mechanism to effectively couple energy to achieve high power and high density. The purpose is to provide a composite plasma source for producing the plasma of the above.

The composite plasma source according to the present invention includes a first microwave resonance chamber, a second microwave resonance chamber, a reaction chamber including at least a pair of metal tubes, and two hollow zones fitted in the hollow metal tubes, respectively. At least one ferrite transformer core comprising a ferrite core, an induction coil entwined with the ferrite core by the two hollow zones, and a drive power source electrically connected to the induction coil. Both ends of the hollow metal tube communicate with the first microwave resonance chamber and the second microwave resonance chamber, respectively, and at least one microwave is introduced into the reaction chamber. , The working gas in the reaction chamber is excited to generate plasma, and the drive power source is electrically connected to the induction coil, whereby an induced electric current is generated in the hollow metal tube of the reaction chamber. However, the induced electric field is characterized in that by exciting the plasma, a current having a closed path is formed in the reaction chamber to further dissociate the working gas and increase the density of the plasma. ..

The composite plasma source according to the present invention is characterized in that an electric current circulates in a first microwave resonance chamber, a hollow metal tube and a second microwave resonance chamber to form a closed path.

The composite plasma source according to the present invention further comprises at least one microwave source, wherein the microwave source is a first microwave resonance chamber, a second microwave resonance chamber, or a first microwave resonance chamber of the reaction chamber. It is provided in the second microwave resonance chamber and is characterized in that it is for introducing microwaves into the reaction chamber.

The composite plasma source according to the present invention includes a magnetron, a central metal rod, and a cylindrical outer tube, the microwave source being coaxially provided, and the central metal rod is located in the cylindrical outer tube and is central. One end of the metal rod is connected to the output antenna of the magnetron, and the other end of the central metal rod extends into the reaction chamber, so that the microwave generated by the magnetron passes through the central metal rod and the cylindrical outer tube. , It is characterized by being introduced into a reaction chamber.

In the composite plasma source according to the present invention, the microwave source further comprises a microwave matching element, and the microwave matching element reacts via the central metal rod and the cylindrical outer tube of the microwave generated by the magnetron. It is intended to reduce the amount of reflection when introduced into the chamber, which is characterized in that microwaves enter the reaction chamber.

In the composite plasma source according to the present invention, the microwave matching element is provided with a metal coaxial tube provided in a cylindrical outer tube along the lateral direction, and the metal coaxial tube is provided coaxially with the horizontal tube. It has a metal plate and a crossbar, the crossbar is provided in the cylindrical outer tube along the lateral direction, the crossbar extends from the cylindrical outer tube to the crossbar, and the metal plate becomes the crossbar. It is characterized by being provided.

The composite plasma source according to the present invention is characterized in that the metal plate is provided so as to be movable on the crossbar, impedance matching is performed, and the amount of microwave reflection is improved.

The composite plasma source according to the present invention is provided with a radial gradient zone between the output antenna and the central metal rod, whereby the microwave output antenna generated by the magnetron is conducted to the central metal rod. It is characterized by reducing the amount of reflection.

The composite plasma source according to the present invention is characterized in that the cylindrical outer tube is a ceramic tube.

The composite plasma source according to the present invention is characterized in that the cylindrical outer tube is a closed vacuum tube.

In the composite plasma source according to the present invention, both ends of the hollow metal tube communicate with the first microwave resonance chamber and the second microwave resonance chamber via at least one electric barrier zone, respectively. It is characterized by preventing a short circuit from being generated between the reaction chamber and the ferrite transformer core.

The composite plasma source according to the present invention is characterized in that the electrical barrier zone is a ceramic ring.

The composite plasma source according to the present invention is characterized in that the first microwave resonance chamber and the second microwave resonance chamber are hollow cylinders.

The composite plasma source according to the present invention is characterized in that the atmospheric pressure of the working gas is higher than 1 Torr and the gas flow rate is higher than 10 slm.

In the composite plasma source according to the present invention, the number and / or the diameter of the hollow metal tube increases as the flow rate of the working gas increases, thereby ensuring the stability of the plasma in the hollow metal tube. It is characterized by increasing air conduction.

The composite plasma source according to the present invention is characterized in that the power density of the plasma corresponds to the number of hollow metal tubes.

The composite plasma source according to the present invention is characterized in that the number of ferrite transformer cores is two sets, and the induction coil is connected in parallel to a drive power source for supplying electric power.

In the composite plasma source according to the present invention, the electric field generated by the ferrite transformer core is perpendicular to the central metal rod that introduces the microwave into the reaction chamber, thereby interfering with the microwave source that generates the microwave. It is characterized by avoiding it.

The composite plasma source according to the present invention is characterized in that the drive power source is an AC power source, a DC power source, or a pulse power source.

The composite plasma source according to the present invention is characterized in that the first microwave resonance chamber has a gas inlet and the second microwave resonance chamber has a gas outlet.

The composite plasma source according to the present invention has the following effects.
(1) A composite plasma source is constructed by a mechanism in which microwave plasma and TCP plasma are combined.
(2) Using the microwave resonance chamber, a high-intensity electric field is generated to generate plasma, and then the energy is effectively coupled by the TCP mechanism to generate high-power and high-density plasma. ..
(3) The shortcomings of the high-voltage ignition device can be solved, and since the microwave excites and holds the initial plasma, the shortcomings due to the weak electric field of TCP can be solved, and the stability of the plasma can be solved. Can be improved.
(4) By utilizing the characteristic that the reaction chamber has a strong electric field, the density of plasma can be kept constant even if the process conditions are adjusted. Even if the atmospheric pressure is 1 Torr to 5 Torr, a high-intensity electric field can be effectively excited, and the requirement for stable plasma generation can be met.
(5) Depending on the magnitude of the flow rate of the working gas, the number of sets of hollow metal pipes can be increased to disperse the flow rate. The stability of the plasma can be ensured and the air conduction can be increased.
(6) Since the plasma according to the present invention is excited by microwaves, the electrical barrier zone according to the present invention can be widened, which is advantageous for an increase in life and stability of the system.
(7) When the flow rate of gas is large, the pressure of gas can be maintained in the range of several Torr.
(8) In order to disperse the power of each set of hollow metal tubes, the energy density of each hollow metal tube is reduced to reduce the conversion of plasma from the diffusion mode to the control mode. be able to.
(9) Using the high-intensity electric field in the reaction chamber, the plasma is stably excited at high pressure and large gas flow rate to provide sufficient free electrons, and the plasma is driven by the induced electric field of the ferrite transformer core. By accelerating, an electron drift current in the closed path is formed in the reaction chamber to effectively dissociate the gas and generate a high-density plasma.

It is sectional drawing which shows the annular vacuum chamber of the annular low electric field plasma source of the prior art. It is sectional drawing which shows the composite plasma source which concerns on this invention. It is a figure which looked at the operation of the composite plasma source which concerns on this invention from another viewpoint. It is sectional drawing which shows the microwave source of the composite plasma source which concerns on this invention. It is sectional drawing which shows the ferrite transformer core of the composite plasma source which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The proportions of each member in the drawings of embodiments of the present invention are shown for easy understanding of the description and are not actual proportions. Further, the ratio of the dimensions of the assembly shown in the figure is for explaining each part and its structure, and of course, the present invention is not limited to this. On the other hand, for convenience of understanding, the same parts in the following embodiments will be described with the same reference numerals.

In addition, terms used throughout the specification and in the utility model claims are commonly used in this field, as disclosed herein, and as used in any particular context, unless otherwise stated. Has the meaning of. Some terms used to describe the invention are described below or elsewhere herein to provide those skilled in the art with additional guidance regarding the description of the invention.

The use of "first", "second", "third", etc. in this article does not specifically indicate the order or sequence, nor is it used to limit the present invention. It is used only to distinguish between the components or operations described in the same terminology.

Second, when terms such as "contain", "prepare", "have", and "contain" are used in this article, they are all open terms. This means that they include, but are not limited to.

The composite plasma source according to the present invention combines microwave plasma (Microwave Plasma) and transformer coupled plasma (Transformer Coupled Plasma, TCP) technology to form a composite plasma source for dissociation and chemical activation of working gas. It is a device and a method for generating high power and high density plasma at high pressure and large gas flow rate.
In the present invention, first, a high-intensity electric field (microwave electric field) is generated in a microwave resonance chamber by microwaves, plasma is generated by a working gas, and energy is effectively cupped by transformer-coupled plasma technology. It rings to generate an electron drift current due to plasma discharge, and further dissociates the working gas effectively to generate high power and high density plasma.

2 to 5 are referenced. The composite plasma source 100 according to the present invention includes a reaction chamber 10 and at least one ferrite transformer core 50. The reaction chamber 10 includes a first microwave resonance chamber 12, a second microwave resonance chamber 14, and at least a pair of hollow metal tubes 16. Both ends of the hollow metal tube 16 communicate with the first microwave resonance chamber 12 and the second microwave resonance chamber 14, respectively.
First, the reaction chamber 10 generates plasma with the working gas 200 by microwaves, and the ferrite transformer core 50 generates an induced electric field 400 (this is a TCP induced electric field). This excites the plasma and discharges the plasma to generate an electric current. As shown in FIG. 2, the first microwave resonance chamber 12 and the second microwave resonance chamber 14 are, for example, hollow cylinders along the lateral direction. The pair of hollow metal tubes 16 communicate with the first microwave resonance chamber 12 and the second microwave resonance chamber 14, respectively, and are provided at a distance from each other.
The above-mentioned ferrite transformer core 50 includes a ferrite core 52, an induction coil 56, and a drive power supply 58. The ferrite core 52 includes at least two hollow zones 54. The hollow zones 54 each fit a pair of hollow metal tubes 16 of the reaction chamber 10. The ferrite core 52 exhibits, for example, a "day" shape. The induction coil 56 utilizes the above two hollow zones 54 to be entwined with the ferrite core 52, for example, with a crossbar in the center of the ferrite core 52 having a "day" shape. The drive power source 58 generates an induction electric field 400 in the reaction chamber 10 (for example, in the hollow metal tube 16) by being electrically connected to both ends of the induction coil 56 via an electric wire, for example.
The induced electric field 400 stably excites the plasma to provide sufficient free electrons, and is driven and accelerated by an electric field generated by the induction of the ferrite core 52. Therefore, a closed-path current (for example, an electron drift current) can be formed in the reaction chamber 10, and the gas is effectively dissociated to generate a high-density plasma. The electron drift current forms a closed path by circulating in the reaction chamber 10 through the first microwave resonance chamber 12, the hollow metal tube 16, and the second microwave resonance chamber 14. As a result, the working gas 200 can be further dissociated to increase the plasma density. The type of the working gas 200 according to the present invention is not particularly limited, and any gas can be used as the working gas 200 according to the present invention as long as plasma can be generated. The dimensions of the reaction chamber 10 and the spacing and diameter of the hollow metal tubes 16 can be determined according to actual needs and are not limited to the above examples.

The composite plasma source according to the present invention utilizes a high-intensity electric field in the first microwave resonance chamber 12 and the second microwave resonance chamber 14 of the reaction chamber 10, and uses a high pressure and a large gas flow rate (pressure> 1 Torr). , Gas flow rate> 1 slm), stably excites the plasma, provides sufficient free electrons, is driven by an electric field induced by the ferrite transformer core 50, and is accelerated into a closed path in the reaction chamber 10. An electron drift current is formed, and the gas is effectively dissociated to generate a high-density plasma.
The technique of transformer coupling can send energy to the plasma very effectively, but like many inductance coupled plasma devices, the strength of the inductive electromagnetic field (10V / cm) penetrates the working gas 200. Not enough. In particular, at high pressure and large gas flow rate, the high voltage device can be used to generate a primitive discharge in the reaction chamber 10 (vacuum chamber) to achieve the purpose of generating plasma, but the high voltage discharge device can achieve the purpose. The life and availability are limited, and the reaction chamber 10 itself is vulnerable to destruction. In particular, inductively coupled plasma (TCP) belongs to the mechanism of low electric field strength, and when the air pressure or air flow is disturbed (for example, when the process changes the flow rate of the working gas), the plasma tends to become unstable and the fire is extinguished. I have something to do. In the present invention, the characteristic that the first microwave resonance chamber 12 and the second microwave resonance chamber 14 of the reaction chamber 10 have a strong microwave electric field 300 is utilized, and a constant plasma is maintained even when the process conditions are adjusted. Since the density can be maintained, the above-mentioned drawbacks can be overcome.

On the other hand, at high pressure, high flow rate, and high power density, the cylindrical plasma (cylindrical plasma volume) in the annular vacuum chamber tends to shrink in the prior art due to the collision of ions and electrons and the limitation of bipolar diffusion. This prevents the plasma from filling the vacuum chamber, further makes the plasma unstable, and limits the power density and barometric airflow that a single metal tube used by the prior art annular vacuum chamber can withstand. Be done.
On the other hand, in the present invention, the flow rate of the working gas is dispersed by the combination of the larger microwave resonance chamber and a plurality of sets of metal tubes, and the power density in each metal tube is reduced by the method of grouping the power sources. , High pressure and high flow operation targets can be achieved.

Specifically, a gas inlet 11 for introducing the working gas 200 is provided on one side of the first microwave resonance chamber 12 described above. A gas outlet 15 for deriving the working gas 200 is provided on one side of the second microwave resonance chamber 14. The gas inlet 11 and the gas outlet 15 are located, for example, on opposite sides of the first microwave resonance chamber 12 and the second microwave resonance chamber 14, respectively. The first microwave resonance chamber 12 and the second microwave resonance chamber 14 are hollow cylinders. The hollow metal tubes 16 are preferably provided so as to be paired. As a result, the working gas 200 flows symmetrically through the hollow metal tube 16.
The number of hollow metal tubes 16 may be one pair, for example, two pairs or more. The hollow metal tubes 16 are preferably spaced apart from each other. Both ends of the hollow metal tube 16 communicate with, for example, the opposite sides of the first microwave resonance chamber 12 and the second microwave resonance chamber 14, respectively. Since many applications relate to the generation of high flow rates of corrosive activated particles (eg, NF ₃ , SF ₆ plasma), it is necessary to protect the interior of the metal reaction chamber 10. Therefore, in the present invention, the aluminum reaction chamber 10 (provided with the first microwave resonance chamber 12, the second microwave resonance chamber 14 and the hollow metal tube 16) is selectively anodized. To form a protective film.

The present invention further comprises at least one microwave source 20 for generating microwaves. The microwave source 20 introduces microwaves into the reaction chamber 10, the resonance frequency is 2.45 GH, the power is in the range of 800 W to 1000 W, for example, and the resonance mode is TE ₁₁₁ mode. As a result, the working gas 200 in the reaction chamber 10 is excited to generate plasma by utilizing the high-intensity microwave electric field 300 of the first microwave resonance chamber 12 and the second microwave resonance chamber 14. The number of the above microwave sources 20 may be one, and is provided in the first microwave resonance chamber 12 or the second microwave resonance chamber 14 of the reaction chamber 10, for example, as shown in FIG. 2, the side surface. Or it is located on the upper surface.
The direction of microwave conduction from the microwave source 20 is preferably perpendicular to the hollow metal tube 16. On the other hand, the number of microwave sources 20 may be, for example, two or more. Then, it can be provided in the first microwave resonance chamber 12 and the second microwave resonance chamber 14 of the reaction chamber 10. In the present invention, as shown in FIG. 5, four hollow metal tubes 16 and two microwave sources 20 have been described as examples, but the present invention is not limited thereto. On the other hand, since the number of hollow zones 54 of the ferrite core 52 corresponds to the hollow metal tube 16, in the present invention, two sets of ferrite transformer cores 50 are taken as an example, which has a “rice field” shape. The two induction coils 56 of the two sets of ferrite transformer cores 50 are each entwined with the two ferrite cores 52 by utilizing the two pairs of hollow zones 54. The two induction coils 56 are electrically connected in parallel to, for example, a drive power source 58, and supply electric power to the induction coils 56.

Specifically, as shown in FIG. 4, the microwave source 20 according to the present invention is, for example, a coaxial magnetron microwave source, and a magnetron 22 provided to be coaxial, a central metal rod 24, and the like. A cylindrical outer tube 26 is provided. The magnetron 22 is provided in the reaction chamber 10. One end of the central metal rod 24 is connected to the output antenna 23 of the magnetron 22, and the other end of the central metal rod 24 extends into the reaction chamber 10. The central metal rod 24 is located inside the cylindrical outer tube 26. Thereby, the microwave from the magnetron 22 can be introduced into the reaction chamber 10 via the central metal rod 24 and the cylindrical outer tube 26.
The cylindrical outer tube 26 is preferably a closed vacuum tube. This, in addition to maintaining the vacuum, can prevent the plasma from coming into direct contact with the central metal rod 24. As the material of the cylindrical outer tube 26, for example, ceramic is adopted, and it is preferable that the material is alumina ceramic. The diameters of the output antenna 23 and the central metal rod 24 may be, for example, the same. On the other hand, when the diameters of the output antenna 23 and the central metal rod 24 are different, for example, when one of them has a larger diameter and the other has a smaller diameter, the output antenna 23 and the central metal rod 24 according to the present invention have different diameters. A diameter gradient zone 25 having a larger diameter at one end and a smaller diameter at the other end may be selectively provided between the two. As a result, the amount of reflection when the microwave output from the magnetron 22 is conducted from the output antenna 23 to the central metal rod 24 can be reduced. The radial gradient zone 25 may be located at the end of the output antenna 23 or at the end of the central metal rod 24, as long as the effect of lowering the reflection of microwaves can be achieved.

Further, the microwave source 20 according to the present invention further selectively includes a microwave matching element 30. The microwave matching element 30 is for reducing the amount of reflection of microwaves from the magnetron 22 when introduced into the reaction chamber 10 via the central metal rod 24 and the cylindrical outer tube 26. The microwave matching element 30 can effectively send microwaves to the reaction chamber 10.
The microwave matching element 30 includes, for example, a metal coaxial tube provided on the cylindrical outer tube 26 along the lateral direction. The metal coaxial tube has a horizontal tube 32a, a metal plate 32b, and a crossbar 32c, which are coaxially provided. The horizontal pipe 32a is provided on the cylindrical outer pipe 26 along the lateral direction. The crossbar 32c extends from the cylindrical outer tube 26 to the horizontal tube 32a. The metal plate 32b is provided on the crossbar 32c. The metal plate 32b is movably provided on the crossbar 32c. When impedance matching is performed by adjusting the position of the metal plate 32b, the amount of microwave reflection can be improved, and the first microwave resonance chamber 12 and the second microwave resonance chamber 14 of the reaction chamber 10 can be improved. In addition, microwaves can be sent effectively.
Since the quality factor of the first microwave resonance chamber 12 and the second microwave resonance chamber 14 exceeds 2,000, a high-intensity electric field can be effectively excited, and the atmospheric pressure is 1 Torr or more. Under the condition of 5 Torr, the requirement to stably generate plasma can be achieved. On the other hand, in general, the collision frequency between the free electron and the neutral gas molecule is about several GHz / Torr. Since this collision frequency is close to the microwave frequency of 2.45 GHz in a pressure range of several Torr, it is advantageous for the microwave to excite the plasma in a pressure range higher than 1 Torr.

As shown in FIG. 2, the first microwave resonance chamber 12 and the second microwave resonance chamber 14 of the reaction chamber 10 communicate with each other by a hollow metal tube 16. The hollow metal tube 16 has a tube diameter of, for example, 2.5 cm, and the quantity and / or the tube diameter can be increased as the flow rate of the working gas 200 increases. That is, in the present invention, the number of sets of the hollow metal pipe 16 can be increased to disperse the flow rate depending on the flow rate of the working gas 200. As a result, the stability of the plasma in the hollow metal tube 16 can be ensured, and further, the air conduction (gas conductance) can be increased.
Further, the diameter of the gas outlet 15 of the reaction chamber 10 may be 5 cm. Since this diameter is smaller than the cut-off diameter (Cut-off) of the 2.45 GHz microwave, the microwave cannot be transmitted, and the influence on the characteristics of the second microwave resonance chamber 14 is extremely small. However, since the air conduction of the system according to the present invention increases more than the 2.5 cm of the prior art, the pressure of the reaction chamber 10 drops, and the plasma of a large gas flow rate is excited in the microwave resonance chamber. It is advantageous for performance. Further, the plurality of hollow metal tubes 16 can increase the power density inside the hollow metal tube 16 and the microwave resonance chamber, that is, the power density of the plasma corresponds to the quantity of the hollow metal tubes 16. As a result, it is possible to realize a state in which the plasma has an extremely high density at a relatively high vacuum pressure and a large gas flow rate (> 1 Torr,> 10 slm), and it is possible to achieve the function of activating the gas.

Further, as shown in FIGS. 3 and 5, the hollow metal tube 16 of this set inserts a pair of central hollow zones 54 of the ferrite core 52 of the ferrite transformer core 50. When the ferrite transformer core 50 is electrically connected to the AC drive power source 58, an induced electric field 400 is generated in the reaction chamber 10, and a current is excited in the plasma. However, the structure of the reaction chamber 10 needs to be electrically insulated. Otherwise, the ferrite transformer core 50 will be short-circuited and the inductive electric field 400 cannot be generated in the reaction chamber 10. In the present invention, this electrical insulation is achieved by using a ceramic ring at the junction of the hollow metal tube 16 with the first microwave resonance chamber 12 and the second microwave resonance chamber 14.
The electric field excited by the ferrite transformer core 50 is concentrated in the electrical barrier zone 17 formed of the ceramic ring due to the influence of the metal structure of the reaction chamber 10. In the prior art, if the electrical barrier zone is not small enough, it is not possible to generate a sufficiently strong electric field and excite the plasma to maintain it stably. However, strong electric fields can cause regional discharges that can explode the ceramic ring and destroy electrical insulation, and can also reverse discharge to damage the drive power supply or protect the reaction chamber. Layer detachment occurs. Since the plasma according to the present invention is excited by the first microwave resonance chamber 12 and the second microwave resonance chamber 14, the electric field strength of the electrical barrier zone is not an important parameter, but is related to the present invention. Since the electrical barrier zone may be wider, the drawbacks of the prior art described above can be reduced, which is advantageous for extended life and system stability.

In the present invention, as shown in FIG. 5, a plurality of hollow metal tubes 16 and two or a plurality of ferrite cores 52 related thereto may be adopted. These ferrite cores 52 are connected in parallel with a single primary current source (that is, the drive power source 58) to supply electric power, thereby supporting the electron drift current in the plasma in the hollow metal tube 16. FIG. 5 shows that the electron drift current in the plasma in the plurality of hollow metal tubes 16 is in the plasma in the reaction chamber 10 (first microwave resonance chamber 12, second microwave resonance chamber 14 and hollow metal tube 16). Shows how they work together. On the other hand, since the angle formed by the electric field induced by the ferrite transformer core 50 and the central metal rod 24 inserted into the reaction chamber 10 is 90 degrees, interference does not occur with the microwave source 20.

FIG. 5 further shows a power supply circuit for the driving TCP plasma according to the present invention. This power supply circuit includes a drive power supply 58, a ferrite transformer core 50, and plasma. In the present invention, the drive power source 58 will be described by taking an AC power source as an example. The frequency of the AC power source to be adopted is capable of driving the plasma and is appropriately determined by the voltage and current that can be withstood by the power element and the loss of the ferrite core 52, and falls in the range of about 100 kHz to 500 kHz. The AC power supply is operated with a constant power or a constant current. The output voltage is in the range of about 250V to 350V, and the maximum power is 10kW.
In the prior art, the load impedance of the AC power supply changes extremely from a low-density plasma to a stable high-density plasma during the process of exciting the plasma, which poses a great challenge to the power element. In comparison with this, in the present invention, since the microwave resonance chamber excites plasma of a constant density at the initial stage, the dynamic change can be significantly reduced and the probability that the power element fails can be reduced. .. Further, the drive power supply 58 of the drive microwave source 20 according to the present invention may be a direct current or a pulse, and the voltage may be increased to about 1 kV from, for example, a switching circuit via a high voltage transformer. The magnetron is driven via a voltage doubler circuit, and its operating power is in the range of 50W to 1000W. The specifications of a conventional magnetron can withstand almost total internal reflection, which is advantageous for starting plasma.

According to the composite plasma source according to the present invention, there are the following effects.
(1) A composite plasma source is constructed by a mechanism in which microwave plasma and TCP plasma are combined.
(2) Using the microwave resonance chamber, a high-intensity electric field is generated to generate plasma, and then the energy is effectively coupled by the TCP mechanism to generate high-power and high-density plasma. ..
(3) The shortcomings of the high-voltage ignition device can be solved, and since the microwave excites and holds the initial plasma, the shortcomings due to the weak electric field of TCP can be solved, and the stability of the plasma can be solved. Can be improved.
(4) By utilizing the characteristic that the reaction chamber has a strong electric field, the density of plasma can be kept constant even if the process conditions are adjusted. Even if the atmospheric pressure is 1 Torr to 5 Torr, a high-intensity electric field can be effectively excited, and the requirement for stable plasma generation can be met.
(5) Depending on the magnitude of the flow rate of the working gas, the number of sets of hollow metal pipes can be increased to disperse the flow rate. The stability of the plasma can be ensured and the air conduction can be increased.
(6) Since the plasma according to the present invention is excited by microwaves, the electrical barrier zone according to the present invention can be widened, which is advantageous for an increase in life and stability of the system.
(7) When the flow rate of gas is large, the pressure of gas can be maintained in the range of several Torr.
(8) In order to disperse the power of each set of hollow metal tubes, the energy density of each hollow metal tube is reduced to reduce the conversion of plasma from the diffusion mode to the control mode. be able to.
(9) Using the high-intensity electric field in the reaction chamber, the plasma is stably excited at high pressure and large gas flow rate to provide sufficient free electrons, and the plasma is driven by the induced electric field of the ferrite transformer core. By accelerating, an electron drift current in the closed path is formed in the reaction chamber to effectively dissociate the gas and generate a high-density plasma.

The above description is merely an example and does not limit the device. Any modification or modification of the equivalent effect made to it that does not deviate from the spirit and category of the present invention is included in the appended claims.

10 Reaction chamber 11 Gas inlet 12 First microwave resonance chamber 14 Second microwave resonance chamber 15 Gas outlet 16 Hollow metal tube 17 Electrical barrier zone 20 Microwave source 22 Magnetron 23 Output antenna 24 Central metal rod 25 Diameter gradient zone 26 Cylindrical outer tube 30 Microwave matching element 32a Horizontal tube 32b Metal plate 32c Crossbar 50 Ferrite transformer core 52 Ferrite core 54 Hollow zone 56 Inductive coil 58 Drive power supply 100 Combined plasma source 200 Working gas 300 Microwave electric field 400 Inductive electric field 500 Vacuum chamber 502 Ferrite transformer core 504 Ceramic ring 506 Gas inlet 508 Gas outlet

Claims (20)

A first microwave resonance chamber, a second microwave resonance chamber, and a reaction chamber with at least a pair of hollow metal tubes.
A ferrite core having two hollow zones fitted in the hollow metal tube, an induction coil entwined with the ferrite core by the two hollow zones, and a drive power supply electrically connected to the induction coil. And with at least one ferrite transformer core,
Both ends of the hollow metal tube communicate with the first microwave resonance chamber and the second microwave resonance chamber, respectively.
The at least one microwave is introduced into the reaction chamber to excite the working gas in the reaction chamber to generate plasma.
The drive power source is electrically connected to the induction coil, thereby generating an inductive electric field in the hollow metal tube of the reaction chamber.
The induced electric field is characterized in that by exciting the plasma, a current having a closed path is formed in the reaction chamber to further dissociate the working gas and increase the density of the plasma.
Combined plasma source. The composite according to claim 1, wherein the current circulates in the first microwave resonance chamber, the hollow metal tube, and the second microwave resonance chamber to form the closed path. Plasma source. Further, the microwave source includes at least one microwave source, and the microwave source is the first microwave resonance chamber, the second microwave resonance chamber, or the first microwave resonance chamber and the second microwave of the reaction chamber. The composite plasma source according to claim 1, further comprising the microwave resonance chamber of the above, wherein the microwave is introduced into the reaction chamber. The microwave source includes a magnetron, a central metal rod, and a cylindrical outer tube provided coaxially, the central metal rod is located in the cylindrical outer tube, and one end of the central metal rod is located. The microwave generated by the magnetron, which is connected to the output antenna of the magnetron and the other end of the central metal rod extends into the reaction chamber, passes through the central metal rod and the cylindrical outer tube. The composite plasma source according to claim 3, wherein the composite plasma source is introduced into the reaction chamber. The microwave source further comprises a microwave matching element, which is delivered to the reaction chamber via the central metal rod of the microwave generated by the magnetron and the cylindrical outer tube. The composite plasma source according to claim 4, wherein the microwave is intended to reduce the amount of reflection when introduced, whereby the microwave enters the reaction chamber. The microwave matching element includes a metal coaxial tube provided in the cylindrical outer tube along the lateral direction, and the metal coaxial tube is coaxially provided with a horizontal tube, a metal plate, and a cross. The crossbar has a bar and is provided on the cylindrical outer tube along the lateral direction, and the crossbar extends from the cylindrical outer tube to the horizontal tube and is a metal plate. The composite plasma source according to claim 5, wherein is provided on the crossbar. The composite plasma source according to claim 6, wherein the metal plate is movably provided on the crossbar and impedance matching is performed to improve the reflection amount of the microwave. A radial gradient zone is provided between the output antenna and the central metal rod, whereby the amount of reflection of the microwave generated by the magnetron when conducted from the output antenna to the central metal rod is measured. The composite plasma source according to claim 4, characterized in that it is reduced. The composite plasma source according to claim 4, wherein the cylindrical outer tube is a ceramic tube. The composite plasma source according to claim 4, wherein the cylindrical outer tube is a closed vacuum tube. Both ends of the hollow metal tube each communicate with the first microwave resonance chamber and the second microwave resonance chamber via at least one electrical barrier zone, whereby the reaction chamber and the reaction chamber are described. The composite plasma source according to claim 1, wherein a short circuit is prevented from being generated between the ferrite transformer core and the core. The composite plasma source according to claim 11, wherein the electrical barrier zone is a ceramic ring. The composite plasma source according to claim 1, wherein the first microwave resonance chamber and the second microwave resonance chamber are hollow cylinders. The composite plasma source according to claim 1, wherein the air pressure of the working gas is higher than 1 Torr and the gas flow rate is higher than 10 slm. The quantity and / or diameter of the hollow metal tube increases with increasing flow rate of the working gas, thereby ensuring the stability of the plasma in the hollow metal tube and increasing air conduction. The composite plasma source according to claim 1, wherein the combined plasma source is characterized in that. The composite plasma source according to claim 1, wherein the power density of the plasma corresponds to the quantity of the hollow metal tubes. The composite plasma source according to claim 1, wherein the number of the ferrite transformer cores is two sets, and the induction coil is connected in parallel to the drive power source for supplying electric power. .. The electric field generated by the ferrite transformer core is perpendicular to the central metal rod that introduces the microwave into the reaction chamber, whereby it is possible to avoid interfering with the microwave source that generates the microwave. The composite plasma source according to claim 1. The composite plasma source according to claim 1, wherein the drive power source is an AC power source, a DC power source, or a pulse power source. The composite plasma source according to claim 1, wherein the first microwave resonance chamber has a gas inlet and the second microwave resonance chamber has a gas outlet.

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