CN216852480U

CN216852480U - Composite plasma source

Info

Publication number: CN216852480U
Application number: CN202123264454.4U
Authority: CN
Inventors: 寇崇善
Original assignee: Mingyuan Precision Technology Co ltd
Current assignee: Mingyuan Precision Technology Co ltd
Priority date: 2021-12-23
Filing date: 2021-12-23
Publication date: 2022-06-28
Anticipated expiration: 2031-12-23

Abstract

The utility model provides a composite plasma source, which combines the mechanism of microwave plasma and transformer coupling plasma to form the composite plasma source for gas dissociation and chemical activation. The reaction chamber of the compound plasma source is composed of two microwave resonant cavities and a plurality of groups of hollow metal tubes, after the microwave resonant cavities generate high-intensity electric fields to generate plasma, a transformer is used for coupling the high-efficiency coupling mechanism of the plasma to generate high-power and high-density plasma, so that the air conduction can be greatly improved, meanwhile, each group of hollow metal tubes are driven by each group of ferrite transformer magnetic cores to disperse power, the energy density of each hollow metal tube is reduced, the generation that the plasma enters a contraction mode from a diffusion mode (diffusion mode) is reduced, and the operable gas flow can be further improved.

Description

Composite plasma source

Technical Field

The present invention relates to a plasma source, and more particularly to a composite plasma source.

Background

Plasma (Plasma) has been widely used in semiconductor manufacturing and other industrial processes, and has the advantage of decomposing molecules of gas to produce a highly reactive mixture of neutral radicals, ions, atoms, electrons and excited molecules to provide various physical and chemical reactions required for the process. There are many different mechanisms for generating plasma, one of which is to use ferrite transformer core to generate inductively coupled plasma discharge, and the main mechanism is to use a ferrite transformer core 502 to generate an induced electric field in a ring Vacuum Chamber (Toroidal Vacuum Chamber)500, as shown in FIG. 1, so as to discharge gas. One end of the toroidal vacuum chamber 500 is a gas inlet 506 and the other end is a gas outlet 508. This is similar to the transformer principle, in that the power is connected to the primary side of the ferrite transformer core 502 and the plasma becomes the secondary side of the single turn, connected by magnetic flux to form a good coupling efficiency. The induced electric field in the Plasma drives the electron drift current to flow in a closed path along the vacuum chamber 500, and this mechanism is also referred to as Transformer Coupled Plasma (TCP). In the prior art, the ferrite transformer core 502 is connected to a driving AC power source to generate an induced electric field in the toroidal vacuum chamber 500 to excite the current in the plasma. However, the annular vacuum chamber 500 needs to provide an electrical isolation region with the ceramic annular plate 504, otherwise the ferrite transformer core 502 is short-circuited and cannot generate an induced electric field in the annular vacuum chamber 500, and the electrical isolation region needs to be small enough to generate a strong electric field to excite and maintain stable plasma, however, the strong electric field generated by the ferrite transformer core 502 is concentrated in the electrical isolation region formed by the ceramic annular plate 504 under the influence of the metal structure of the annular vacuum chamber 500, which sometimes causes the ceramic annular plate 504 to crack due to local discharge and damages the electrical isolation, even the reverse discharge damages the driving power supply, or causes the problem of falling off of the protective coating of the reaction chamber.

Anderson describes such a process in U.S. patent nos. 3,500,118 and 3,987,334. Us patent No. 4,180,763 proposes the use of ferrite core TCP for lighting applications. Reinberg et al, U.S. Pat. No. 4,431,898, teach the use of plasma to remove photoresist in semiconductor processing. This TCP technique has been applied to plasma sources that provide a large activation rate for the dissociated gas. In some high pressure, high gas flow applications, it is desirable to use a high power density plasma to chemically activate the working gas or to change the properties or composition of the gas, which can then be delivered to a vacuum processing system. Such applications are referred to as "remote plasma processing" and include: (1) remote chamber cleaning; (2) polymer watchRemote chamber ashing of the face; (3) downstream foreline cleaning and aftertreatment gas abatement in the vacuum foreline. Many of these applications involve high flow rates (greater than 1slm) of an electronegative plasma discharge gas (e.g., O)₂、NF₃、SF₆) And relatively high gas pressures (greater than 1 Torr). Therefore, high power densities are typically required to achieve the requirements of high dissociation and activation of the working gas. Under the operation condition of high pressure and high flow rate, as in many inductively coupled plasma source apparatuses, the strength of the inductive electromagnetic field of the TCP is not enough to ignite the plasma discharge, but the plasma discharge must be initiated by introducing a high strength electric field in the vacuum chamber by other means, such as adding a high voltage electrode or introducing a high ac voltage to the electrically isolated partial chamber to generate a local rf glow discharge. However, the lifetime and the rate of the high voltage discharge device are limited, and for example, it has been proposed in the literature to add a resonant circuit to the circuit to generate a high voltage (1-10kV) to effectively generate a local discharge to generate plasma, but after the plasma is generated, if the same voltage is still used, a large current will be generated to damage the power device. Therefore, a high voltage Relay (Relay) must be added to the circuit to quickly switch the power circuit to a non-resonant circuit after the plasma is generated, so as to reduce the voltage and avoid the damage of large current. However, if the relay fails or the control signal is delayed and the relay cannot be activated immediately, the power device will be damaged. On the other hand, the use of high voltage is very likely to cause the damage of the insulated components of the vacuum chamber to cause electrical short circuit, and the plating layer on the chamber wall can fall off and flow into the process chamber to cause particle pollution. For some applications, such as panel display manufacturing, large volumes of gas must be used due to the large size of the processing system (>30slm) to meet process requirements, the operating gas pressure and power density must be significantly increased with the prior art toroidal vacuum chamber configuration. However, in this case, the diameter of the cylindrical plasma (cylindrical plasma) in the vacuum chamber may become smaller due to the collision of ions and electrons, bipolar diffusion (bipolar diffusion) and the limitation of heat dissipation efficiency, so that the plasma enters the contraction mode from the diffusion mode and cannot fill the vacuum chamber, and thus a part of the gas cannot pass through the plasma reactionSo that the overall gas activation rate is reduced and the process requirements cannot be met. In severe cases, even the plasma is unstable, so that the plasma is not maintained and extinguished. Therefore, how to improve the structure of the annular vacuum chamber in the prior art to ensure the stability of the plasma is a problem to be overcome for further increasing the gas flow.

SUMMERY OF THE UTILITY MODEL

In view of the above problems in the prior art, the present invention is to improve the above drawbacks of the conventional TCP plasma technology and to provide a solution for further increasing the flow rate of the working gas. The main technique is that (1) a composite plasma source is formed by combining microwave plasma and TCP plasma, and after the microwave resonant cavity is used to generate high-intensity electric field to generate plasma, high-power and high-density plasma is generated by using TCP to plasma high-efficiency energy coupling mechanism. Therefore, on the one hand, the disadvantage of the high voltage ignition device can be eliminated, and simultaneously, the microwave is responsible for exciting and maintaining the initial plasma, so that the disadvantage of the TCP weak electric field can be solved, and the stability of the plasma can be improved. (2) The reaction Chamber is composed of two microwave resonant cavities and a plurality of groups of hollow metal tubes, compared with the annular Vacuum Chamber (Toroidal Vacuum Chamber) in the prior art, the gas conductance can be greatly improved, so that the gas pressure can be maintained in the range of several Torr under the condition of large gas flow. Meanwhile, the energy density of each hollow metal tube is reduced because the power of each group of hollow metal tubes is dispersed, and the occurrence of plasma entering a Contraction Mode from a Diffusion Mode is reduced.

To achieve the above object, the present invention provides a composite plasma source including a reaction chamber and at least one ferrite transformer core. The reaction chamber comprises a first microwave resonance chamber, a second microwave resonance chamber and at least one pair of hollow metal tubes, wherein two ends of the pair of hollow metal tubes are respectively communicated with the first microwave resonance chamber and the second microwave resonance chamber, and at least one microwave is introduced into the reaction chamber so as to excite a working gas in the reaction chamber into plasma. The ferrite transformer magnetic core comprises a ferrite magnetic core, an induction coil and a driving power supply, wherein the two hollow areas of the ferrite magnetic core are respectively sleeved on the hollow metal tubes, the induction coil is wound on the ferrite magnetic core through the two hollow areas, and the driving power supply is electrically connected with the induction coil, so that an induction electric field is generated in the hollow metal tubes of the reaction cavity, the induction electric field excites the plasma, a current with a closed path is formed in the reaction cavity, and the working gas is further dissociated to improve the density of the plasma.

Wherein the current circulates through the first microwave resonant cavity, the hollow metal tube and the second microwave resonant cavity to form the closed path.

Wherein, at least one microwave source is disposed on the first microwave resonant cavity, the second microwave resonant cavity or both the first microwave resonant cavity and the second microwave resonant cavity of the reaction cavity for guiding the microwave into the reaction cavity.

The microwave source comprises a magnetron, a central metal rod and a cylindrical outer tube which are coaxially arranged, the central metal rod is positioned in the cylindrical outer tube, one end of the central metal rod is connected with an output antenna of the magnetron, and the other end of the central metal rod extends into the reaction cavity, so that the microwave generated by the magnetron is guided into the reaction cavity through the central metal rod and the cylindrical outer tube.

Wherein the microwave source further comprises a microwave matching element for reducing a reflection amount of the microwave generated by the magnetron when the microwave is introduced into the reaction cavity through the central metal rod and the cylindrical outer tube, so that the microwave enters the reaction cavity.

The microwave matching element comprises a metal coaxial tube transversely arranged on the cylindrical outer tube, wherein the metal coaxial tube is provided with a transverse tube, a metal plate and a cross rod which are coaxially arranged, the transverse tube is transversely arranged on the cylindrical outer tube, the cross rod extends into the transverse tube from the cylindrical outer tube, and the metal plate is arranged on the cross rod.

The metal plate is movably arranged on the cross bar so as to carry out impedance matching to improve the reflection quantity of the microwave.

A diameter slowly-changing region is arranged between the output antenna and the central metal rod so as to reduce a reflection quantity of the microwave generated by the magnetron when the microwave is conducted to the central metal rod from the output antenna.

Wherein, the cylindrical outer tube is a ceramic tube.

Wherein, the cylindrical outer tube is a sealed vacuum tube.

Wherein, the two ends of the pair of hollow metal tubes are respectively communicated with the first microwave resonant cavity and the second microwave resonant cavity through at least one electric barrier region, so as to prevent the short circuit between the reaction cavity and the ferrite transformer magnetic core.

Wherein, the electric barrier region is a ceramic annular sheet.

Wherein, the first microwave resonant cavity and the second microwave resonant cavity are hollow cylinders.

Wherein the working gas has a pressure greater than 1Torr and a gas flow greater than 10 slm.

Wherein the number (and/or diameter) of the hollow metal tubes is increased corresponding to the increase of the flow rate of the working gas, thereby ensuring the stability of the plasma in the hollow metal tubes and increasing the gas conductance.

Wherein the power density of the plasma corresponds to the number of the pair of hollow metal tubes.

The number of the ferrite transformer magnetic cores is two, and the induction coils are connected in parallel to the driving power supply to supply power.

Wherein an electric field generated by the ferrite transformer core is perpendicular to a central metal rod for guiding the microwave into the reaction cavity so as to avoid interference with a microwave source for generating the microwave.

Wherein, the driving power supply is an alternating current type power supply, a direct current type power supply or a pulse type power supply.

Wherein the first microwave resonant cavity has a gas inlet and the second microwave resonant cavity has a gas outlet.

Bearing said, according to the utility model discloses a combined type electricity thick liquid source, it can have one or more following advantages:

(1) the microwave plasma and TCP plasma are combined to form a composite plasma source. (2) After the microwave resonant cavity is used to generate high-intensity electric field to generate plasma, the TCP mechanism is used to effectively couple energy to generate high-power and high-density plasma. (3) The disadvantage of high voltage ignition device can be eliminated, and the microwave is responsible for exciting and maintaining the initial plasma, so that the disadvantage of TCP weak electric field can be solved, and the stability of plasma can be improved. (4) By using the characteristic of strong electric field in the reaction chamber, a certain plasma density can be maintained even when the process conditions are adjusted, and the high-intensity electric field can be effectively excited to meet the requirement of stably generating plasma even if the pressure is 1Torr to 5 Torr. (5) The number of groups of hollow metal tubes can be increased to disperse the flow according to the gas flow of the working gas, thereby not only ensuring the stability of the plasma but also increasing the gas conductance.

(6) Because the utility model discloses a plasma has been aroused by the microwave, so the utility model discloses an electric property separation district can the broad, is favorable to life's extension and the stability of system. (7) The gas pressure can be maintained in the range of several Torr in the case of a large gas flow. (8) Because the power of each group of hollow metal tubes is dispersed, the energy density of each hollow metal tube is reduced, and the occurrence of plasma entering a Contraction Mode from a Diffusion Mode is reduced. (9) The utility model discloses utilize the electric field of high strength in the reaction chamber to arouse under high atmospheric pressure and high gas flow and stabilize electric thick liquid and provide abundant free electron to the electric field drive that generates via ferrite magnetic transformer core induction and with higher speed, form the electron drift current of closed route in the reaction chamber, and further effective free gas production high density electric thick liquid.

In order to make the jun have a better understanding and appreciation of the technical features and technical effects of the invention, the preferred embodiments and the accompanying detailed description are considered in the following.

Drawings

FIG. 1 is a schematic cross-sectional view of a toroidal vacuum chamber of a toroidal low-electric-field plasma source of the prior art.

FIG. 2 is a schematic cross-sectional view of a hybrid plasma source according to the present invention.

FIG. 3 is another view of the composite plasma source of the present invention.

FIG. 4 is a schematic cross-sectional view of a microwave source of the composite plasma source of the present invention.

FIG. 5 is a schematic cross-sectional view of a ferrite transformer core of the composite plasma source of the present invention.

Description of reference numerals:

10: reaction chamber 24: central metal bar 56: induction coil

11: gas inlet 25: diameter graded region 58: driving power supply

12: first microwave resonant cavity 26: cylindrical outer tube 100: composite plasma source

14: the second microwave resonant cavity 30: microwave matching element 200: working gas

15: gas outlet 32 a: the transverse tube 300: microwave electric field

16: hollow metal tube 32 b: metal plate 400: induced electric field

17: electrical blocking region 32 c: cross bar 500: vacuum chamber

20: the microwave source 50: ferrite transformer core 502: ferrite transformer core

22: magnetron 52: ferrite core 504: ceramic ring plate

23: output antenna 54: hollow area 506: gas inlet

508: gas outlet

Detailed Description

In order to understand the technical features, contents, advantages and effects achieved by the present invention, the present invention will be described in detail with reference to the drawings and the embodiments, wherein the drawings are used for illustration and assistance of the specification, and are not necessarily the actual proportion and the precise configuration after the present invention is implemented, so the attached drawings should not be interpreted and the scope of the right of the present invention in the actual implementation is limited by the proportion and the configuration relationship. In addition, for the sake of easy understanding, the same elements in the following embodiments are illustrated with the same reference numerals.

Furthermore, the words used throughout the specification and claims have the ordinary meaning as is usually accorded to each word used in the art, in the context of this disclosure and in the context of particular integers, unless otherwise indicated. Certain words used to describe the present authoring are discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the present authoring.

The terms "first," "second," "third," and the like, as used herein, are not intended to be limited to the specific order or sequence presented, nor are they intended to be limiting, but rather are intended to distinguish one element from another or from another element or operation described by the same technical term.

Furthermore, as used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The utility model discloses a combined type Plasma source, and combine Microwave Plasma (Microwave Plasma) and Transformer Coupled Plasma (TCP) technique to constitute combined type Plasma source in order to carry out working gas dissociation and chemical activation, thereby produce high power and high density Plasma's device and method under high pressure and high gas flow. The utility model discloses earlier with the microwave produce high strength electric field (microwave electric field) at microwave resonance cavity and make working gas form electric thick liquid, with transformer coupling electric thick liquid technique effective coupling energy again for electric thick liquid discharges and produces electron drift current, and further effectively frees working gas in order to produce high power and high density electric thick liquid.

Referring to FIGS. 2-5, a hybrid plasma source 100 includes a chamber 10 and at least one ferrite transformer core 50. The reaction chamber 10 comprises a first microwave resonance cavity 12, a second microwave resonance cavity 14 and at least a pair of hollow metal tubes 16, wherein two ends of the hollow metal tubes 16 are respectively communicated with the first microwave resonance cavity 12 and the second microwave resonance cavity 14, wherein the reaction chamber 10 uses a microwave to make the working gas 200 form plasma, and the ferrite transformer core 50 generates an induced electric field 400 (which is a TCP induced electric field) for exciting the plasma to discharge to generate current. As shown in fig. 2, the first microwave resonant cavity 12 and the second microwave resonant cavity 14 are, for example, horizontal hollow cylinders, and the pair of hollow metal tubes 16 are respectively connected to the shafts of the first microwave resonant cavity 12 and the second microwave resonant cavity 14 and are spaced apart from each other. The ferrite transformer core 50 includes a ferrite core 52, an induction coil 56, and a driving power supply 58. The ferrite core 52 has at least two hollow regions 54 respectively sleeved on the pair of hollow metal tubes 16 of the reaction chamber 10. The ferrite core 52 is, for example, in a shape of a "Chinese character ri". The induction coil 56 is wound around the ferrite core 52 by the two hollow regions 54, for example, on the middle cross bar of the "ri" shaped ferrite core 52, and the driving power source 58 is electrically connected to the two ends of the induction coil 56, for example, via wires, so as to generate an induced electric field 400 in the reaction chamber 10 (for example, in the hollow metal tube 16), wherein the induced electric field 400 can excite the stable plasma to provide sufficient free electrons, and can be driven and accelerated by the electric field induced by the ferrite core 52, so as to form a closed path current (for example, an electron drift current) in the reaction chamber 10, and further effectively ionize the gas to generate a high density plasma. The electron drift current circulates in the chamber 10 through the first microwave cavity 12, the hollow metal tube 16 and the second microwave cavity 14 to form a closed path, thereby further dissociating the working gas 200 and increasing the plasma density. The type of the working gas 200 of the present invention is not particularly limited, and any gas may be used as long as it can generate plasma, and thus the working gas 200 of the present invention can be suitably used. The size of the reaction chamber 10 and the spacing and diameter of the hollow metal tubes 16 can be determined according to practical requirements, and are not limited to the above examples.

The utility model discloses a combined type electricity thick liquid source utilizes the electric field of the first microwave resonant cavity 12 of reaction chamber 10 and the high strength in second microwave resonant cavity 14 to arouse under high atmospheric pressure and high gas flow (atmospheric pressure >1Torr, gas flow >1slm) and stabilize electric thick liquid and provide abundant free electron to the electric field drive that produces via the induction of ferrite transformer magnetic core 50 and with higher speed, form the electron drift current of closed route in reaction chamber 10, and further effectively free gas production high density electricity thick liquid. Although the transformer coupling technique can effectively transmit energy into the plasma, as with many inductively coupled plasma devices, the strength (10V/cm) of the induced electromagnetic field is not sufficient to break down the working gas 200, especially under high pressure and high gas flow rate, although the initial discharge can be generated in the reaction chamber 10 (vacuum chamber) by using a high voltage device to achieve the goal of generating plasma, the service life and the rate of the high voltage discharge device are limited, and the damage to the chamber of the reaction chamber 10 is easily caused. In particular, transformer-coupled plasma (TCP) is a mechanism with low electric field intensity, and when there is disturbance in the gas pressure or gas flow, it is very easy to make the plasma unstable or even extinguish, for example, when the process switches the flow of working gas. The present invention utilizes the characteristic that the first microwave resonant cavity 12 and the second microwave resonant cavity 14 of the reaction chamber 10 have strong microwave electric field 300, so that a certain plasma density can be maintained even when the process conditions are adjusted, thereby overcoming the disadvantage.

On the other hand, under high pressure, high flow rate and high power density, the cylindrical plasma (plasma column) in the annular vacuum chamber of the prior art is easily contracted due to the collision of ions and electrons and the limitation of bipolar diffusion (bipolar diffusion), so that the plasma cannot fill the vacuum chamber, even the plasma is unstable, and the annular vacuum chamber of the prior art can bear limited power density and pressure gas flow by using a single metal tube. In comparison, the present invention disperses the working gas flow rate by the combination of the larger microwave resonant cavity and the plurality of groups of metal tubes, and reduces the power density in each metal tube by grouping the power sources, thereby achieving the goal of high pressure and high flow rate operation.

In detail, one side of the first microwave resonant cavity 12 has a gas inlet 11 for introducing the working gas 200, one side of the second microwave resonant cavity 14 has a gas outlet 15 for discharging the working gas 200, and the gas inlet 11 and the gas outlet 15 are respectively disposed at opposite sides of the first microwave resonant cavity 12 and the second microwave resonant cavity 14. The first microwave resonant cavity 12 and the second microwave resonant cavity 14 are hollow cylinders. The hollow metal tubes 16 are preferably arranged in pairs such that the working gas 200 can flow through the hollow metal tubes 16 symmetrically, wherein the number of the hollow metal tubes 16 may be one pair, or two or more pairs, for example, and the hollow metal tubes 16 are preferably spaced apart from each other. The hollow metal tube 16 has both ends respectively communicating with each other, for exampleOn opposite sides of the first microwave resonant cavity 12 and the second microwave resonant cavity 14. Since many applications involve the generation of high flux corrosive activated particles (e.g., NF)₃、SF₆Plasma), the interior of the metal chamber 10 must be protected, so the present invention can selectively anodize the aluminum chamber 10 (including the first microwave resonant cavity 12, the second microwave resonant cavity 14 and the hollow metal tube 16) to form a protective film.

The utility model further comprises at least one microwave source 20 for generating microwave, and guiding the microwave into the reaction chamber 10, wherein the resonant frequency is 2.45GH, the power is between 800W to 1000W, and the resonant mode is TE₁₁₁The high intensity microwave electric field 300 of the first microwave cavity 12 and the second microwave cavity 14 is used to excite the working gas 200 in the reaction chamber 10 into plasma. The number of the microwave sources 20 may be one, and the microwave sources 20 are disposed on the first microwave cavity 12 or the second microwave cavity 14 of the reaction chamber 10, for example, on the side (as shown in fig. 2) or the top side, and the propagation direction of the microwaves generated by the microwave sources 20 is preferably perpendicular to the disposition direction of the hollow metal tube 16. In addition, the number of the microwave sources 20 may be two or more, for example, for being disposed on the first microwave cavity 12 and the second microwave cavity 14 of the reaction chamber 10 at the same time. As shown in fig. 5, the present invention is exemplified by four hollow metal tubes 16 and two microwave sources 20, but not limited thereto. In addition, since the number of the hollow areas 54 of the ferrite cores 52 corresponds to the hollow metal tube 16, the present invention takes two sets of ferrite cores 50 as an example, and the two sets of ferrite cores 50 are shaped like a Chinese character tian, wherein the two induction coils 56 of the two sets of ferrite cores 50 are respectively wound around the two ferrite cores 52 by the two pairs of hollow areas 54, and the two induction coils 56 are electrically connected to a driving power source 58 in parallel, for example, to supply power to the induction coils 56.

In detail, as shown in fig. 4, the microwave source 20 of the present invention is, for example, a coaxial magnetron microwave source, which includes a magnetron 22, a central metal rod 24 and a cylindrical outer tube 26, which are coaxially disposed. The magnetron 22 is disposed on the reaction chamber 10, one end of a central metal rod 24 is connected to an output antenna 23 of the magnetron 22, the other end of the central metal rod 24 extends into the reaction chamber 20, and the central metal rod 24 is disposed in a cylindrical outer tube 26, so that the microwave generated by the magnetron 22 can be introduced into the reaction chamber 20 through the central metal rod 24 and the cylindrical outer tube 26. The cylindrical outer tube 26 is preferably a sealed vacuum tube, which can prevent the plasma from directly contacting the central metal rod 24 in addition to maintaining vacuum, and can be made of ceramic, preferably alumina ceramic. The diameters of the output antenna 23 and the central metal rod 24 may for example be the same. In addition, if the diameters of the output antenna 23 and the central metal rod 24 are different, for example, one of them has a larger diameter and the other has a smaller diameter, the present invention can selectively provide a diameter graded region 25 between the output antenna 23 and the central metal rod 24, wherein the diameter of one end is larger and the diameter of the other end is smaller, so as to reduce the reflection amount when the microwave generated by the magnetron 22 is transmitted from the output antenna 23 to the central metal rod 24. Wherein, this diameter gradual change district 25 can be located the tip of output antenna 23, or is located the tip of central metal rod 24, as long as can reach the effect that reduces the microwave reflection and can be applicable to the utility model discloses.

In addition, the microwave source 20 of the present invention may further selectively include a microwave matching element 30 for reducing the reflection amount of the microwave generated by the magnetron 22 when the microwave is introduced into the reaction chamber 10 through the central metal rod 24 and the cylindrical outer tube 26, so that the microwave can be effectively transmitted into the reaction chamber 10. The microwave matching element 30 comprises a coaxial metal tube having a transverse tube 32a, a metal plate 32b and a cross bar 32c, wherein the transverse tube 32a is disposed transversely on the outer cylindrical tube 26, the cross bar 32c extends from the outer cylindrical tube 26 into the transverse tube 32a, and the metal plate 32b is disposed on the cross bar 32 c. The metal plate 32b is movably disposed on the cross bar 32c, and the position of the metal plate 32b is adjusted to perform impedance matching, so as to improve the reflection amount of the microwave, and the microwave can be effectively transmitted into the first microwave resonant cavity 12 and the second microwave resonant cavity 14 of the reaction cavity 10. The quality factor (quality factor) of the first microwave cavity 12 and the second microwave cavity 14 can exceed 2,000, so that the high-intensity electric field can be effectively excited to meet the requirement of stably generating plasma at a gas pressure of 1Torr to 5 Torr. On the other hand, in general, the collision frequency of free electrons and neutral gas molecules is about several GHz/Torr, which is close to 2.45GHz in the pressure range of several Torr and the microwave frequency, thereby facilitating the microwave to excite the plasma in the pressure range higher than 1 Torr.

As shown in fig. 2, the first microwave resonant cavity 12 and the second microwave resonant cavity 14 of the reaction chamber 10 are connected by a hollow metal tube 16, the diameter of the hollow metal tube 16 is, for example, 2.5cm, and the number and/or diameter of the hollow metal tubes 16 can be increased corresponding to the increase of the flow rate of the working gas 200. That is, the utility model discloses can be according to the size of the gas flow of working gas 200, increase the group number of hollow metal tube 16 with the dispersion flow, not only can ensure that electric thick liquid stability in hollow metal tube 16 can increase the gas conductance (gas conductance), the diameter of the gas outlet 15 of reaction chamber 10 can multiplicable be 5cm simultaneously, this diameter is less than the cutoff diameter (Cut-off) of 2.45GHz microwave, the microwave can not transmit, it is very little to second microwave cavity 14 characteristic influence. However, compared with the prior art 2.5cm, the system of the present invention has much increased air conductance and thus reduced pressure in the reaction chamber 10, which is beneficial to the microwave resonant cavity to excite the high-flow plasma. In addition, the plurality of hollow metal tubes 16 can constructively increase the power density in the hollow metal tubes 16 and the microwave resonant cavity, i.e. the power density of the plasma corresponds to the number of the hollow metal tubes 16, so as to achieve a very high density plasma state under a relatively high vacuum pressure and a high gas flow rate (>1Torr, >10slm), and achieve the function of activating the gas.

In addition, as shown in fig. 3 and 5, the set of hollow metal tubes 16 passes through a pair of central hollow areas 54 of the ferrite core 52 of the ferrite transformer core 50. The ferrite transformer core 50 is connected to an AC power source 58 to generate an induced electric field 400 in the chamber 10to excite a current in the plasma. However, the structure of the reaction chamber 10 needs to be electrically isolated, which may cause short circuit to the ferrite transformer core 50 and prevent the induced electric field 400 from being generated in the reaction chamber 10. In the present invention, the electrical isolation is achieved by using ceramic ring sheets at the junction of the hollow metal tube 16 and the first microwave cavity 12 and the second microwave cavity 14. The electric field excited by the ferrite transformer core 50 is concentrated in the electric isolation region 17 formed by the ceramic ring plate under the influence of the metal structure of the reaction chamber 10. In the conventional technique, the electric isolation region must be small enough to generate strong electric field strength to excite and maintain stable plasma, however, the strong electric field sometimes causes local discharge to cause the ceramic annular sheet to break and destroy the electric isolation, even reverse discharge damages the driving power, or causes the problem of peeling off of the protective coating of the reaction chamber. In contrast, since the plasma of the present invention is excited by the first microwave resonant cavity 12 and the second microwave resonant cavity 14, the electric field intensity of the electric barrier region is not a critical parameter, so the electric barrier region of the present invention can be wider, thereby reducing the disadvantages of the above-mentioned conventional techniques, and being beneficial to the prolonging of the service life and the stability of the system.

As shown in fig. 5, the present invention may also employ a plurality of hollow metal tubes 16 and associated two or more ferrite cores 52, with these ferrite cores 52 being powered in parallel with a separate primary current source (i.e., a drive power supply 58) to support the induced electron drift current of the plasma in the hollow metal tubes 16. FIG. 5 shows how the induced electron drift currents of the plasma in the plurality of hollow metal tubes 16 work together in the plasma in the reaction chamber 10 (the first microwave resonance chamber 12, the second microwave resonance chamber 14 and the hollow metal tubes 16). On the other hand, the electric field induced by the ferrite core 50 is 90 degrees to the central metal rod 24 inserted into the reaction chamber 10, and thus does not interfere with the microwave source 20.

Fig. 5 further shows the power circuit of the present invention for driving TCP plasma, wherein the power circuit is composed of a driving power source 58, a ferrite transformer core 50 and plasma. The present invention takes the driving power source 58 as an example of an ac power source, and the frequency of the ac power source is suitably selected to be suitable for driving the plasma, the withstand voltage and the withstand current of the power device, and the loss of the ferrite core 52, which is between about 100kHz and about 500 kHz. The ac power source may be constant power or constant current operation. The output voltage is about 250V to 350V and the maximum power is 10 kW. In the prior art, the load impedance of the ac power source varies greatly from low-density plasma to stable high-density plasma during the plasma excitation process, which poses a great challenge to the power device. In contrast, in the present invention, the initial microwave resonant cavity has excited a constant density of plasma. Therefore, the dynamic change of the load impedance can be greatly reduced, and the probability of the power element problem is reduced. In addition, the driving power supply 58 of the microwave source 20 of the present invention may be dc or pulse type, for example, the voltage may be increased to about 1kV by a switching (switching) circuit through a high voltage transformer, and then the magnetron may be driven by a voltage doubling circuit, with an operating power of 50W-1000W. With the specifications of the existing magnetron, almost total reflection can be tolerated, so that it is advantageous for exciting the starting plasma.

To sum up, the utility model discloses a combined type electric thick liquid source has following advantage: (1) the microwave plasma and TCP plasma are combined to form a composite plasma source. (2) After the microwave resonant cavity is used to generate high-intensity electric field to generate plasma, the TCP mechanism is used to effectively couple energy to generate high-power and high-density plasma. (3) The disadvantage of high voltage ignition device can be eliminated, and the microwave is responsible for exciting and maintaining the initial plasma, so that the disadvantage of TCP weak electric field can be solved, and the stability of plasma can be improved. (4) By using the characteristic of strong electric field in the reaction chamber, a certain plasma density can be maintained even when the process conditions are adjusted, and the high-intensity electric field can be effectively excited to meet the requirement of stably generating plasma even if the pressure is 1Torr to 10 Torr. (5) The number of groups of hollow metal tubes can be increased to disperse the flow according to the gas flow of the working gas, thereby not only ensuring the stability of the plasma but also increasing the gas conductance. (6) Because the utility model discloses a plasma has been aroused by the microwave, so the utility model discloses an electric property separation district can the broad, is favorable to life's extension and the stability of system. (7) The gas pressure can be maintained in the range of several Torr in the case of a large gas flow. (8) Because the power of each group of hollow metal tubes is dispersed, the energy density of each hollow metal tube is reduced, and the occurrence of plasma entering a Contraction Mode from a Diffusion Mode is reduced. (9) The utility model discloses utilize the electric field of reaction chamber high strength to arouse under high atmospheric pressure and high gas flow that stable electric thick liquid provides abundant free electron to the electric field drive that generates via ferrite transformer core responds to and with higher speed, forms the electron drift current of closed route in the reaction chamber, and further effective free gas production high density electric thick liquid.

The foregoing is by way of example only, and not limiting. It is intended that all equivalent modifications or changes made without departing from the spirit and scope of the present invention shall be included in the scope of the appended claims.

Claims

1. A composite plasma source, comprising:

a reaction chamber, which comprises a first microwave resonance cavity, a second microwave resonance cavity and at least a pair of hollow metal tubes, wherein two ends of the pair of hollow metal tubes are respectively communicated with the first microwave resonance cavity and the second microwave resonance cavity, and at least one microwave is introduced into the reaction chamber so as to excite a working gas in the reaction chamber into plasma; and

at least one ferrite transformer core, the ferrite transformer core includes a ferrite core having two hollow regions respectively sleeved on the hollow metal tube, an induction coil wound around the ferrite core by the two hollow regions and a driving power supply electrically connected to the induction coil to generate an induction electric field in the hollow metal tube of the reaction chamber, the induction electric field excites the plasma to form a current with a closed path in the reaction chamber, thereby further dissociating the working gas to increase the density of the plasma.

2. The composite plasma source of claim 1, wherein: the current circulates through the first microwave resonant cavity, the pair of hollow metal tubes and the second microwave resonant cavity to form the closed path.

3. The composite plasma source of claim 1, wherein: at least one microwave source is disposed in the first microwave resonant cavity, the second microwave resonant cavity, or both the first microwave resonant cavity and the second microwave resonant cavity of the reaction cavity for guiding the microwave into the reaction cavity.

4. The composite plasma source of claim 3, wherein: the microwave source comprises a magnetron, a central metal rod and a cylindrical outer tube which are coaxially arranged, the central metal rod is positioned in the cylindrical outer tube, one end of the central metal rod is connected with an output antenna of the magnetron, and the other end of the central metal rod extends into the reaction cavity, so that the microwave generated by the magnetron is guided into the reaction cavity through the central metal rod and the cylindrical outer tube.

5. The composite plasma source of claim 4, wherein: the microwave source further includes a microwave matching element for reducing a reflection amount of the microwave generated by the magnetron when the microwave is introduced into the reaction chamber through the central metal rod and the cylindrical outer tube, so that the microwave enters the reaction chamber.

6. The composite plasma source of claim 5, wherein: the microwave matching element comprises a metal coaxial tube transversely arranged on the cylindrical outer tube, wherein the metal coaxial tube is provided with a transverse tube, a metal plate and a cross rod which are coaxially arranged, the transverse tube is transversely arranged on the cylindrical outer tube, the cross rod extends into the transverse tube from the cylindrical outer tube, and the metal plate is arranged on the cross rod.

7. The composite plasma source of claim 6, wherein: the metal plate is movably arranged on the cross bar so as to carry out impedance matching to improve the reflection quantity of the microwave.

8. The plasma source of claim 4, wherein the output antenna has a diameter graded region with respect to the central metal rod to reduce a reflection of the microwave generated by the magnetron as the microwave is transmitted from the output antenna to the central metal rod.

9. The composite plasma source of claim 4, wherein: the cylindrical outer tube is a ceramic tube.

10. The composite plasma source of claim 4, wherein: the cylindrical outer tube is a sealed vacuum tube.

11. The composite plasma source of claim 1, wherein: the two ends of the hollow metal tube are respectively communicated with the first microwave resonant cavity and the second microwave resonant cavity through at least one electric barrier region, so as to prevent short circuit between the reaction cavity and the ferrite transformer magnetic core.

12. The composite plasma source of claim 11, wherein: the electrical isolation region is a ceramic annular sheet.

13. The composite plasma source of claim 1, wherein: the first microwave resonant cavity and the second microwave resonant cavity are hollow cylinders.

14. The composite plasma source of claim 1, wherein: the working gas has a pressure greater than 1Torr and a gas flow greater than 10 slm.

15. The composite plasma source of claim 1, wherein: the number and/or diameter of the hollow metal tubes are increased corresponding to the increase of the flow of the working gas, thereby ensuring the stability of the plasma in the hollow metal tubes and increasing the gas conduction.

16. The composite plasma source of claim 1, wherein: the power density of the plasma corresponds to the number of the pair of hollow metal tubes.

17. The composite plasma source of claim 1, wherein: the ferrite transformer cores are two in number, and the induction coils are connected in parallel to the driving power supply to supply power.

18. The composite plasma source of claim 1, wherein: an electric field generated by the ferrite transformer core is perpendicular to a central metal rod for guiding the microwave into the reaction cavity so as to avoid interference with a microwave source for generating the microwave.

19. The composite plasma source of claim 1, wherein: the driving power supply is an alternating current type power supply, a direct current type power supply or a pulse type power supply.

20. The composite plasma source of claim 1, wherein: the first microwave resonant cavity has a gas inlet and the second microwave resonant cavity has a gas outlet.