CN211792198U - Resonant cavity type ECR plasma source device - Google Patents

Resonant cavity type ECR plasma source device Download PDF

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Publication number
CN211792198U
CN211792198U CN201921134276.3U CN201921134276U CN211792198U CN 211792198 U CN211792198 U CN 211792198U CN 201921134276 U CN201921134276 U CN 201921134276U CN 211792198 U CN211792198 U CN 211792198U
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antenna
vacuum
resonant cavity
plasma
ecr
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刘宇
张仲恺
雷久侯
曹金祥
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University of Science and Technology of China USTC
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University of Science and Technology of China USTC
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Abstract

The utility model discloses a resonant cavity formula ECR plasma source device, the utility model discloses technical scheme sets up in the vacuum cavity with the antenna seal cover, arranges the antenna that radiates the microwave in this antenna seal cover, can avoid the discharge antenna right ECR plasma pollutes in the vacuum cavity. The electron density can be further increased by adjusting the magnitude of the magnetic field required for electron cyclotron resonance by the ECR control element. The device has the advantages of simple structure and high electromagnetic wave-plasma energy coupling efficiency, and can generate electron density up to 1012cm‑3A magnitude of plasma.

Description

Resonant cavity type ECR plasma source device
Technical Field
The present invention relates to the field of plasma source generation technology, and more particularly, to a resonant cavity type ECR (electron cyclotron resonance) plasma source device.
Background
Electron Cyclotron Resonance (ECR) plasma is an important technology in the field of low-pressure low-temperature discharge. The ECR plasma source uses microwave energy to excite gas discharge, and has the advantages of long service life, stable performance, no electrode, corrosion resistance, and being capable of operating under vacuum, so that the ECR plasma source is widely used in various fields, such as a high current ion source in an accelerator, ion implantation in semiconductor manufacturing, ion beam sputtering deposition, and new concept space electric propulsion engine technology. There are many types of existing ECR plasma source arrangements, such as typical high aspect ratio and low aspect ratio ECR plasma sources, where microwaves are transmitted through a waveguide to create a plasma in a resonance region under the influence of a coil magnetic field through a glass window, or where microwave energy is delivered using a microwave transmitting antenna to create an electron cyclotron resonance region in conjunction with a permanent magnet magnetic field.
The microwave resonant cavity can be used for plasma generation, the principle is that a strong electromagnetic field is generated in the microwave resonant cavity through the resonance effect of an electromagnetic field, gas discharge is excited to generate plasma, but the electron density of the generated plasma reaches 10 under the control of the plasma oscillation frequency and the resonant cavity manufacturing process9cm-3In the magnitude, the microwave corresponding to the frequency of 2.45GHz is cut off at the boundary of non-magnetized plasma, and the energy can not enter the plasma, so that the electron density of the general microwave resonant cavity plasma source is low, and the high density requirement required by industrial application is difficult to achieve.
The inventor researches and discovers that the plasma source combining the microwave resonant cavity and the ECR discharge technology can not only use the resonant cavity to enhance the energy coupling efficiency of electromagnetic waves, but also use the ECR principle to enable electron cyclotron resonance to absorb microwave energy, thereby combining the advantages of two discharge modes and generating high-density plasma under the conditions of small space and lower microwave power consumption.
SUMMERY OF THE UTILITY MODEL
The application aims to provide a resonant cavity type ECR plasma source device, which comprises the following technical scheme:
a resonant cavity ECR plasma source apparatus comprising:
the vacuum resonant cavity is used for enabling the microwave with set frequency to generate resonance;
an antenna sealing cover disposed within the vacuum resonant cavity, the antenna sealing cover having an antenna opening for connection to an external atmosphere;
an antenna disposed in the antenna enclosure through the antenna opening, the antenna for radiating the microwaves through the antenna enclosure to the vacuum cavity;
and the ECR control element is arranged outside the vacuum resonant cavity and used for generating a magnetic field required by electron cyclotron resonance in the vacuum resonant cavity so as to generate ECR plasma in the vacuum resonant cavity.
Preferably, in the above apparatus, the vacuum resonance chamber includes: the cylinder body, the bottom of cylinder body is sealed, and its top is provided with resonance reinforcing ring.
Preferably, in the above apparatus, the ECR control element is a magnetic field coil, and is wound by a multi-turn coil and connected to a dc regulated power supply.
Preferably, in the above apparatus, the magnetic field coil is an electromagnetic coil wound with enamel wire.
Preferably, in the above apparatus, the antenna sealing cover is a quartz glass cover.
Preferably, in the above apparatus, the antenna is a rod antenna, one end of which is placed in the antenna sealing cover through the antenna opening, and the other end of which is connected to a microwave source generating circuit;
the rod antenna is internally provided with a water cooling structure.
Preferably, in the above apparatus, a side wall of the cylinder body has a passage through which cooling water circulates, and an outer side of the side wall of the cylinder body has a water inlet and a water outlet connected to a cooling water pipe.
Preferably, in the above device, the side wall of the cylinder body further has a quick connection flange for connecting a vacuum pump set and a vacuum gauge for measuring vacuum pressure.
Preferably, in the above apparatus, the side wall of the cylinder body further has a CF flange for mounting a plasma measuring device.
It can be known from the above description that the technical solution of the present invention provides a resonant cavityIn the ECR plasma source device, an antenna sealing cover is arranged in a vacuum resonant cavity, and an antenna for radiating microwave is arranged in the antenna sealing cover, so that ECR plasma in the vacuum resonant cavity can be prevented from being polluted by a discharge antenna. The electron density can be further increased by adjusting the magnitude of the magnetic field required for electron cyclotron resonance by the ECR control element. The device has the advantages of simple structure and high electromagnetic wave-plasma energy coupling efficiency, and can generate electron density up to 1012cm-3A magnitude of plasma.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a resonant cavity type ECR plasma source apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an antenna sealing cover according to an embodiment of the present invention;
FIG. 3a is a graph of axial strength of a gauss meter measuring the vacuum cavity with a field coil current of 9A;
FIG. 3b is a graph of the radial intensity of the vacuum cavity measured by a gaussmeter at a field coil current of 9A;
FIG. 3c is a diagram of the Gaussian gauge measuring the total magnetic induction in the vacuum cavity when the current of the magnetic field coil is 9A;
FIG. 4a is a schematic diagram of electron density at the center of the vacuum cavity as a function of discharge power and gas pressure;
FIG. 4b is a graph showing the electron temperature at the center of the vacuum cavity as a function of discharge power and gas pressure.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a resonant cavity type ECR plasma source apparatus according to an embodiment of the present invention, the apparatus includes: a vacuum resonant cavity 10 for resonating microwaves of a set frequency; an antenna sealing cover 4 disposed in the vacuum resonant cavity 10, the antenna sealing cover 4 having an antenna opening connected to an external atmosphere; an antenna 5 disposed in the antenna enclosure 4 through the antenna opening, the antenna 5 being configured to radiate the microwaves through the antenna enclosure 4 to the vacuum cavity 10; and the ECR control element 7 is arranged outside the vacuum resonant cavity 10 and is used for generating a magnetic field required by electron cyclotron resonance in the vacuum resonant cavity 10 so as to generate ECR plasma in the vacuum resonant cavity.
The vacuum resonant cavity 10 includes: the cylinder body, the bottom of cylinder body is sealed, and its top is provided with resonance reinforcing ring 2. The resonant cavity 10 is used as a generating container of ECR plasma, needs vacuum sealing, and is made of stainless steel material with low magnetic permeability so as to avoid noise magnetic field interference. Therefore, the cylinder body is a stainless steel cylinder and is sealed in vacuum. The outer diameter of the resonance-enhancing ring 2 may be set equal to the inner diameter of the vacuum resonance chamber 10 so as to be directly fixed to the inner wall of the vacuum resonance chamber. The difference between the inner diameter and the outer diameter of the resonance enhancement ring 2 is 22mm, namely the width of the resonance enhancement ring 2 is 22mm, so that the microwave energy coupling efficiency in the vacuum resonant cavity 10 can be effectively improved.
The inner diameter of the vacuum resonant cavity 10 satisfies a resonance condition, so that the microwaves resonate in the vacuum resonant cavity 10, increasing the microwave coupling energy. Therefore, when the vacuum resonant cavity is used for generating plasma under a microwave source with set frequency, a resonance effect can be generated, and microwave energy coupling can be effectively increased.
The inner diameter of the vacuum cavity 10 (the inner diameter of the cylindrical body) is set to be N times of the wavelength of the microwave, where N is a positive integer greater than N, for example, N may be 2, so that the diameter of the vacuum cavity 10 is N times or approximately N times of the wavelength of the microwave, so that the microwave generates resonance, for example, the frequency is 2.45GHZ, and the inner diameter of the vacuum cavity 10 may be set to be 245 mm. The diameter of the vacuum cavity 10 is approximately N times the microwave wavelength, representing: the difference between the diameter of the vacuum resonant cavity 10 and N times the microwave wavelength is not more than a set threshold to satisfy the resonance condition, and the set threshold may be set according to the actual resonance, for example, the threshold is not more than 5% of the microwave wavelength. The axial height of the vacuum resonant cavity 10 (the height of the cylindrical body) can be set to 150mm, and the height can be set based on the requirement, and is not limited to 1500 mm.
Optionally, the side wall of the cylinder body is provided with a cooling water circulation channel, and the outer side of the side wall of the cylinder body is provided with a water inlet interface 1 and a water outlet interface which are connected with a cooling water pipe. That is to say, the side wall of the vacuum resonant cavity 10 is of a sandwich structure, cooling water can be introduced to cool the inner wall, and the cooling water circulates in the sandwich, so that the plasma source can perform stable plasma discharge. Only the water inlet connection is shown in fig. 1, and the water outlet connection is not shown.
Optionally, the side wall of the cylinder body is further provided with a quick connection flange 3, and the quick connection flange 3 is used for connecting a vacuum pump set and a vacuum gauge for measuring vacuum pressure.
The side wall of the cylinder body is also provided with a CF flange 6, and the CF flange 6 is used for mounting a plasma measuring device.
The ECR control element 7 is a magnetic field coil, is wound by a plurality of turns of coils, is used for being connected with a direct current stabilized power supply, adopts the direct current stabilized power supply for supplying power, and can generate a 875Gs magnetic field area required by ECR plasma in the vacuum resonant cavity 10 when the current is less than 10A. Optionally, the magnetic field coil is an electromagnetic coil wound by enameled wires.
The antenna sealing cover 4 is a quartz glass cover. The antenna sealing cover 4 is made of quartz glass and can withstand plasma baking for a long time. The antenna sealing cover 4 isolates the antenna 5 from the vacuum environment of the vacuum resonant cavity 10, and isolates plasma in the vacuum resonant cavity 10 from the antenna 5 in the antenna sealing cover 4, so that the connection of a microwave device at the rear end of the antenna 5 can be protected while the charged antenna is prevented from polluting the plasma in the vacuum resonant cavity 10.
The antenna 5 is a rod-shaped antenna, one end of the antenna is arranged in the antenna sealing cover 4 through the antenna opening, and the other end of the antenna is connected with a microwave source generating circuit; the rod antenna is internally provided with a water cooling structure, such as a water cooling structure. After the microwave energy generated by the microwave source generating circuit is converted into the antenna 5, the microwave energy is transmitted into the vacuum resonant cavity 10 through the antenna 5, the antenna 5 is in the atmospheric environment and is not contacted with plasma, the antenna is cooled by an internal cooling structure, and the heat load generated during the transmission of the microwave energy is reduced. The rod-shaped antenna has a simple structure, a cooling structure is arranged in the rod-shaped antenna, the mode of generating an electromagnetic field is simple, and the plasma is uniformly distributed.
In the embodiment of the present invention, the structure of the antenna sealing cover 4 is as shown in fig. 2, and fig. 2 is the embodiment of the present invention provides a schematic structural diagram of the antenna sealing cover, a left side of fig. 2 is a top view of one end of the antenna sealing cover 4 with an antenna opening, and a right side of fig. 2 is a sectional view of the left side of fig. a-a'. The antenna sealing cover 4 is shown as a cylindrical structure with one end sealed and the other end having an opening to facilitate placement of the antenna 5. The antenna sealing cover 4 is installed on the top of the vacuum resonant cavity 10, and seals vacuum with the top sealing part on the vacuum resonant cavity 10, and the resonance enhancing ring 2 is attached to the inner surface of the top sealing part. The antenna opening of the antenna sealing cover 4 is communicated with the atmosphere, so that the inside of the antenna sealing cover 4 is the atmosphere, and the outer wall of the antenna sealing cover is arranged in the vacuum resonant cavity 10 and is in the vacuum environment.
Aiming at the existing microwave resonanceThe chamber plasma density is low, complicated with ECR plasma device structure, the embodiment of the utility model provides a novel resonant cavity formula ECR plasma source device, the device have magnetic field coil that magnetic field size is adjustable as ECT control element 7 to produce the required magnetic field of electron cyclotron resonance and further increase electron density, design antenna sealed cowling 4 simultaneously and seal discharge antenna 5, thereby avoid discharge antenna 4 right plasma source causes the pollution in the vacuum cavity 10. The device has simple structure and high electromagnetic wave-plasma energy coupling efficiency, and can generate electron density as high as 1012cm-3A magnitude of plasma.
Can know through the above-mentioned description the embodiment of the utility model provides a device adopts the internal diameter to strengthen the electromagnetic wave coupling effect for 245 mm's vacuum cavity 10, and this vacuum cavity 10's internal diameter is 2 times of 2.45GHz microwave wavelength, when realizing the resonance effect, and the size is less, can effectively increase the resonance effect of microwave. The resonance enhancement ring 2 with a certain width is added in the vacuum resonant cavity 10, so that the microwave energy absorption efficiency in the vacuum resonant cavity 10 can be improved. The side wall of the vacuum resonant cavity 10 has a sandwich structure, and circulating cooling water can be introduced.
Adopt quartz glass as antenna seal cover 4 moreover, carry out vacuum seal to vacuum cavity 10 top, place antenna 5 in antenna seal cover 4, keep apart with plasma, compare in the scheme of traditional discharge antenna submergence in the plasma environment, the utility model discloses antenna seal cover 4 can be so that discharge antenna 5 does not have electric charge among the technical scheme, protects microwave antenna 5 and rear end circuit, avoids antenna impurity to get into the plasma pollution plasma environment simultaneously.
An electromagnetic coil wound by enameled wires is used as the ECR control element 7. The magnetic field gradient of the traditional ECR plasma source using the permanent magnet is extremely large, so that the magnetic field in the plasma is not uniformly distributed, and the electrified coil can generate a relatively uniform magnetic field. In addition, the number of turns of a magnetic field coil wound by the traditional hollow aluminum pipe is small, the size of the magnetic field coil is large, a large-current power supply is needed to be used for supplying power, the current is usually hundreds of amperes, and the cost of the power supply is high. And the utility model discloses among the technical scheme, the multiturn enameled wire that magnetic field coil used can produce the magnetic field that surpasss 900Gs in vacuum cavity 10's central zone under the low-power consumption condition that voltage is 120 volts, electric current are 9A, produces the electron cyclotron resonance region in vacuum cavity 10. As shown in fig. 3, fig. 3 shows the distribution diagram of the axial, radial and total magnetic induction intensity measured by the gaussmeter in the vacuum cavity when the field coil current is 9A, fig. 3 includes fig. 3a, fig. 3b and fig. 3c, fig. 3a is the distribution diagram of the axial intensity measured by the gaussmeter in the vacuum cavity when the field coil current is 9A, fig. 3b is the distribution diagram of the radial intensity measured by the gaussmeter in the vacuum cavity when the field coil current is 9A, fig. 3c is the distribution diagram of the total magnetic induction intensity measured by the gaussmeter in the vacuum cavity when the field coil current is 9A, and it can be seen that when the coil current reaches 9A or more, the magnetic induction intensity in the vacuum cavity 10 in the vicinity of the microwave antenna reaches 875Gs, and the electron cyclotron resonance condition is reached.
Experimental data can be obtained, the cavity type ECR plasma source can generate a magnetic field satisfying the ECR condition intensity in the vacuum cavity, as shown in fig. 4, fig. 4 shows the electron density and the electron temperature of the plasma at the center position in the vacuum cavity measured by using the langmuir probe, and the electron density can be generated at the center of the vacuum cavity and is generally 1012cm-3The magnitude of the plasma shows that the device can meet the design requirement of a high-density plasma source under a certain discharge condition. FIG. 4 includes FIGS. 4a and 4b, in which FIG. 4a is a graph showing the variation of electron density at the center of the vacuum cavity with discharge power and gas pressure, FIG. 4b is a graph showing the variation of electron temperature at the center of the vacuum cavity with discharge power and gas pressure, and the electron density reaches 10 in low-pressure discharge12cm-3On the order of magnitude, the electron temperature is about 0.8-3.5 electron volts (eV).
Based on the above embodiment, another embodiment of the present invention further provides a method for generating an ECR plasma source, which uses the apparatus according to the above embodiment to generate an ECR plasma. The embodiment of the present invention provides a method, which can generate electron density as high as 10 by using the device of the above embodiment12cm-3The magnitude plasma is simple in implementation mode and low in cost.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The method disclosed by the embodiment corresponds to the device disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the device part for description.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in an article or device that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (6)

1. A resonant cavity ECR plasma source apparatus, comprising:
the vacuum resonant cavity is used for enabling the microwave with set frequency to generate resonance;
an antenna sealing cover disposed within the vacuum resonant cavity, the antenna sealing cover having an antenna opening for connection to an external atmosphere;
an antenna disposed in the antenna enclosure through the antenna opening, the antenna for radiating the microwaves through the antenna enclosure to the vacuum cavity;
and the ECR control element is arranged outside the vacuum resonant cavity and used for generating a magnetic field required by electron cyclotron resonance in the vacuum resonant cavity so as to generate ECR plasma in the vacuum resonant cavity.
2. The apparatus of claim 1, wherein the vacuum resonant cavity comprises: the cylinder body, the bottom of cylinder body is sealed, and its top is provided with resonance reinforcing ring.
3. The apparatus of claim 1, wherein said ECR control element is a magnetic field coil wound from a multi-turn coil for connection to a dc regulated power supply.
4. The apparatus of claim 3, wherein the magnetic field coil is a wire-wound electromagnetic coil.
5. The apparatus of claim 1, wherein the antenna enclosure is a quartz glass enclosure.
6. The device according to any of claims 1-5, wherein said antenna is a rod antenna having one end disposed in said antenna enclosure through said antenna opening and another end connected to a microwave source generating circuit;
the rod antenna is internally provided with a water cooling structure.
CN201921134276.3U 2019-07-18 2019-07-18 Resonant cavity type ECR plasma source device Active CN211792198U (en)

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CN201921134276.3U CN211792198U (en) 2019-07-18 2019-07-18 Resonant cavity type ECR plasma source device

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Application Number Priority Date Filing Date Title
CN201921134276.3U CN211792198U (en) 2019-07-18 2019-07-18 Resonant cavity type ECR plasma source device

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CN211792198U true CN211792198U (en) 2020-10-27

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