KR20020091857A - Plasma discharging system by using multiple resonant modes - Google Patents

Abstract

The present invention relates to a discharge system for generating microwave plasma used for plasma material processing applications in superimposed resonance mode using single / multiple frequencies. Conventional microwave plasma discharge systems use a single resonant mode at a fixed single frequency, such as 2.45 GHz or 915 GHz, and mechanically tune and combine energy by varying the position, size, and shape of the tuner included in the resonator 25. Match this up to the maximum. However, the commonly used TM ₀₁₀ basic mode has a limitation in expanding according to the sample size in the resonator 25. In addition, there is an economic and technical problem, such as the uniformity of the plasma treatment state is reduced by the difference between the strong and weak electromagnetic field distribution. The present invention overcomes the limitations of the conventional single mode by exciting the multiple resonant modes through a frequency sweep to improve uniformity in the resonator by using a microwave source that is variable in frequency. In addition, in the selective tuning method using a single frequency, the energy transmission paths from the waveguide to the resonator are different from each other without using a microwave variable source that can vary in wavelength, so that even if the frequencies of the microwaves entering the resonator are fixed to each other, The principle that the other two TE, TM modes are generated is used. By using a wavelength variable source or by varying the coupling method as described above, a large-area uniform plasma can be easily obtained, unlike the prior art, which has a large limitation in large system size by overlapping several resonance modes.

Description

Plasma discharge system using multiple resonant modes {PLASMA DISCHARGING SYSTEM BY USING MULTIPLE RESONANT MODES}

The present invention relates to a plasma discharging system using multiple resonant modes, and more particularly, to a system for discharging microwave plasma used for plasma material processing.

2 is a schematic view showing an embodiment of a microwave plasma discharge system according to the related art, and includes a microwave source 11 and a cavity 12. The microwave generator 11 includes an arc detector 13, a waveguide launcher 14, a magnetron 15, a power supply 16, and a controller ( controller 17, circulator 18, dummy load 19, directional coupler 20, power meter 23, and three stage tuner 3 a stub tuner 24. The resonator 12 includes a resonator 25 and a quartz tube 26.

In the figure, the magnetron 15 in the microwave generator 11 oscillates mainly in the commercially available microwave region of 2.45 GHz or 915 GHz. The microwaves oscillated from the magnetron 15 reach the resonator 25 via the waveguide seater 14, the circulator 18, the directional coupler 20, the three-stage tuner 24, and so forth. The resonator 25 receives microwaves from the three stage tuner 24 to discharge the plasma. The circulator 18 is made of a ferrite material that controls the direction in which the microwave travels, and simulated load 19 when the microwaves oscillated from the magnetron 15 are reflected back from the resonator 25. To proceed. The simulated load 19 has a water cooling unit to absorb the reflected microwaves so that the reflected microwaves do not travel in the direction of the magnetron 15. The directional coupler 20 extracts the reflected power 21 reflected from the resonator 25 and the forward power 22 incident to the resonator 25, and provides them to the output meter 23. The output meter 23 receives the two outputs 21 and 22 provided from the directional coupler 20, respectively, and measures the output 21 reflected from the resonator 25 and the output 22 incident to the resonator 25, respectively. do. The three stage tuner 24 adjusts the impedance between the directional coupler 20 and the resonator 25 so that the microwaves are delivered to the resonator 25 with maximum coupling efficiency.

The quartz tube 26 in the resonator 25 is made of a dielectric material through which microwaves pass but gas particles do not pass, confining certain gases necessary for plasma material processing.

The conventional microwave plasma discharge system uses a single resonant mode at a fixed single frequency, such as 2.45 GHz or 915 GHz, and is mechanically tuned by changing the position, size, and shape of a tuner mounted in the resonator 25. Match to ensure maximum energy coupling. However, the commonly used TM ₀₁₀ basic mode (in the form of electromagnetic or electric field distribution) has a limitation in expanding according to the sample size in the resonator 25. In addition, there is an economic and technical problem, such as the uniformity of the plasma treatment state is reduced by the difference between the strong and weak electromagnetic field distribution.

Accordingly, the present invention has been made to solve the above-mentioned drawbacks of the prior art, and excites a multi-mode with multiple resonant modes inside the resonator, thereby limiting the resonator of the conventional plasma discharge system. It is an object of the present invention to provide a plasma discharge system using a multi-resonance mode that solves the problem of expansion of the circuit and increases the coupling efficiency of the resonator and improves the uniformity of the plasma by the multi-mode.

According to an aspect of the present invention, there is provided a system for discharging a plasma using microwaves in a superposed resonance mode using multiple frequencies: a wavelength variable microwave generation unit capable of sweeping a frequency of a microwave output; It characterized in that it comprises a resonator for generating a plasma using a multi-mode by the microwave input continuously variable frequency provided from the variable microwave generator.

1 is a block diagram showing an embodiment of a plasma discharge system using a multiple resonance mode according to the present invention;

Figure 2 is a schematic diagram showing an embodiment of a microwave plasma discharge system according to the prior art,

3 is a schematic diagram showing an embodiment of a traveling waveguide;

Figure 4 is a block diagram showing an embodiment of a microwave plasma discharge system of the superimposed resonance mode using a single frequency according to the present invention,

5 is a schematic diagram showing the superposition of the TM ₀₁₀ mode and the TE ₀₁₁ mode.

<Description of the symbols for the main parts of the drawings>

1: Driver 2: Separator

3: traveling waveguide 4: circulator

5: directional coupler 6: simulated load

7: resonator 8: waveguide using H-plane

9: waveguide using E-plane

10: output divider 31: electron gun

32: electron beam 33: RF input

34: attenuator 35: focused magnetic field

36: spiral slow wave circuit 37: RF output

38: Collector

Hereinafter, the embodiment of the present invention will be described in detail with reference to the following drawings.

1 is a block diagram showing an embodiment of a plasma discharge system using a multiple resonance mode according to the present invention, a drive (1), an isolator (2), a traveling wave tube (TWT) ( 3) a circulator 4, a directional coupler 5, a simulated load 6, and a resonator 7. The driver 1, separator 2, and traveling waveguide 3 perform a multi-frequency source function.

In the figure, the driver 1 oscillates a microwave. The separator 2 receives the microwaves from the driver 1 and passes them through and not in the opposite direction. The traveling waveguide 3 receives the microwaves oscillated from the driver 1 through the separator 2 to generate multiple frequencies having a wide bandwidth. The traveling waveguide 3 generates a microwave capable of an operating frequency of 1 to 100 GHz, a bandwidth of 10 to 20%, and an output ranging from several watts to several megawatts. Such traveling waveguides 3 are used in various applications such as communication satellites and military radars. Generally, the traveling waveguide 3 is divided into a coupled cavity type used for high power applications and a helix used mainly for broad band operation. In addition to the traveling waveguide 3, other types of microwave generators in which several resonators are connected in a line, such as klystron, may be considered. The separator 2, the circulator 4, and the simulated load 6 prevent reflection and control the microwave in the direction of travel. The directional coupler 5 measures the output incident to the resonator 7 and the output reflected from the resonator 7. The resonator 7 generates plasma using multiple modes.

As such, the system as shown in FIG. 1 is a system in which different modes are generated at each frequency as the frequency is changed. For example, in the resonator 7 where the plasma is generated by using the frequency variable source, a multiple mode is formed in which multiple modes are overlapped, and each overlapping standing wave pattern is more uniform than a single mode. Will be achieved.

The circulator 4 passes the microwaves provided by the traveling waveguide 3 in the direction of the resonator 7 without reflection. The simulated load 6 absorbs the microwaves reflected past the circulator 4 to protect the traveling waveguide 3. The simulated load 6 uses a water cooling unit provided to cool the heat generated when the microwave is absorbed. The microwaves passing through the circulator 4 are passed through the directional coupler 5 into the resonator 7 to cause the discharge of gas molecules in the resonator 7. The reflected microwave output without being coupled with the microwave output coupled into the resonator 7 can be monitored via the directional coupler 5.

In the system of FIG. 1, the multimode distribution formed according to the frequency sweep speed, the bandwidth of the microwave circle, and the output is changed. In order to improve the uniformity of the plasma generated in the resonator (7) is required to optimize the above parameters (parameters). Multi-mode operation is a system in which multiple standing wave distributions overlap and mode control is not limited by the expansion of the plasma resonator.

3 is a schematic view showing an embodiment of the traveling waveguide 3, including an electron gun 31, an electron beam 32, an RF input 33, and an attenuator ( 34), a magnetic focusing field 35, a helix slow-wave circuit 36, an RF output 37, and a collector 38. .

In the figure, when RF is injected into the spiral slow wave circuit 36 through the input terminal 33, the RF output is amplified by receiving energy by interaction with the electron beam 32 generated in the electron gun 31. Obtained from (37).

Figure 4 is a block diagram showing an embodiment of the microwave plasma discharge system of the superimposed resonance mode using a single frequency according to the present invention, the driver 1, the separator 2, the traveling wave tube 3, the circulator 4 , Directional coupler 5, simulated load 6, resonator 7, waveguide 8 using H-plane, waveguide 9 using E-plane, and output divider 10.

In the figure, the driver 1, the separator 2, the traveling waveguide 3, the circulator 4, the directional coupler 5, and the simulated load 6 are similar to those of FIG. Reference is made to the description of 1.

The output divider 10 distributes the microwave output provided from the directional coupler 5 and outputs them to both sides. The waveguide 8 using the H-plane passes a microwave of TE nature, receives one output from the output divider 10 and excites one mode to the resonator 7. The waveguide 9 using the E-plane passes a microwave of TM nature, and receives different output from the output divider 10 to excite the resonator 7 with different modes. Thus, the resonator 7 generates a given plasma using a specific mode of electromagnetic field generated by the superposition of the microwaves excited from the waveguide 8 using the H-plane and the waveguide 9 using the E-plane. .

As described above, in the present invention according to FIG. 4, a selective tuning technique of simultaneously exciting different modes to the resonator 7 using a plurality of E-planes and H-planes according to the number of modes to be excited. Can be used to form multiple modes.

5 is a schematic diagram showing the superposition of the TM ₀₁₀ mode and the TE ₀₁₁ mode.

As described above, the present invention overcomes the limitations of the conventional single mode, such as improving the uniformity in the resonator as a multi-mode operation. In the case of frequency sweeping using a microwave variable source having a variable wavelength or selective tuning using a single frequency, the multi-mode system according to the present invention has several prior arts in terms of size and uniformity because multiple resonance modes are simultaneously excited and overlapped. Limitations can be easily solved.

Claims (6)

A microwave generator for generating microwaves continuously frequency-variable within a set range; A resonator configured to resonate the microwaves applied from the microwave generator, and perform plasma discharge using energy obtained from the multi-mode microwaves generated by overlapping resonance modes generated by the variable frequencies, respectively. Plasma discharge system using a multiple resonance mode configured. The method of claim 1, The resonator may include a circulation unit configured to pass the microwaves generated by the microwave generator without reflection; A directional coupler configured to measure an output incident to the resonator and an output reflected from the resonator; And a simulated load means for absorbing the microwaves reflected past the circulation portion. The method of claim 1, The microwave generation unit is a plasma discharge system using a multiple resonance mode, characterized in that the coupling resonator type or spiral type. A microwave generator for generating a single frequency microwave; An output distribution unit for distributing the output power of the generated microwaves; First waveguide means for receiving an output from the output distributor and transferring the output to a resonator; Second waveguide means for receiving another output from the output distributor and transferring the output to the resonator; The microwaves transmitted by the first and second waveguide means are applied and resonated by E-plane coupling and H-plane coupling, respectively, and the resonance modes generated according to the coupling scheme are generated by overlapping. Plasma discharge system using a multi-resonance mode comprising a resonator for performing a plasma discharge using energy obtained from the multi-mode microwave. The method of claim 4, wherein The waveguide is a plasma discharge system using a multiple resonant mode, characterized in that the width and height is adjusted to change to the TM mode or TE mode. The method of claim 4, wherein The resonator may include a circulation unit configured to pass the microwaves generated by the microwave generator without reflection; A directional coupler configured to measure an output incident to the resonator and an output reflected from the resonator; And a simulated load means for absorbing the microwaves reflected past the circulation portion.