Microwave plasma treatment apparatus
|発明の名称 （英語）||Microwave plasma treatment apparatus|
|発明の概要（英語）||Provided is a microwave plasma treatment apparatus in which a complex, long gas flow path inside a dielectric substrate is eliminated, which allows plasma to be generated and sustained stably.The microwave plasma treatment apparatus makes it possible to generate highly uniform, high-density, and stable low-temperature plasma even at intermediate atmospheric pressures and high atmospheric pressures as well as low atmospheric pressures.The microwave plasma treatment apparatus includes: a dielectric substrate; a microwave input unit; a microstrip line; a ground conductor; a gas inlet; a plasma generating unit; a nozzle for blowing out plasma; etc.In the microwave plasma treatment apparatus, the gas inlet is provided at the ground conductor or the microstrip line.Furthermore, preferably, the diameter of the gas inlet is made smaller than the cutoff wavelength, which is determined according to the cross section of the gas inlet, thereby preventing leakage of microwaves.|
In recent years, research and development or production techniques such as plasma processing techniques in the material becomes an indispensable technique in many fields.A non-thermal equilibrium plasma due to its high are able to generate a high density of free radicals, and thus is widely used in low-temperature drying processes.
As in a low pressure (1 torr or less) and from the intermediate pressure (1 torr-100 torr) to atmospheric pressure at a pressure between one of the plasma source, uses a plasma stream.A plasma flow is a nozzle discharge plasma from the device, so that the wafer by using a plasma CVD of the substrate to be processed (chemical vapor phase synthesis), etching, ashing (resist ashing process), the plasma nitridation and air purification, sterilization, a process of sterilization and the like, is a useful substance.
Now, as a method for generating a plasma stream, using a direct current arc discharge or a DC pulse discharge is well-known method.However, using a direct current arc discharge or a DC pulse discharge method, an electrode can be easily deteriorated, various problems such as not using a reactive gas.
In addition, the use of a dielectric barrier discharge method is also well known.However, the use of a dielectric barrier discharge method, has a creation filamentary discharge, various problems such as high density cannot be generated free radicals.
In addition, it has also been known to have no electrode type plasma stream generating device.For example, proposes the use of VHF band (30-300 MHz) of a high frequency inductively coupled thermal plasma creation device (see Patent Document 1).However, the proposed plasma-flow generating means having an impedance matching complex, due to structural reasons to be made narrower, and because of the use of high-pressure circuit which results in device manufacturing and operational problems that there are various ways.
On the other hand, the use of microwave plasma is generated to flow the following advantages.
(1) a microwave power source is inexpensive.
(2) is capable of operating without the electrodes, the discharge sustain long life.
(3) through a simple device capable of achieving impedance matching.
(4) a microwave and a plasma coupling efficiency is good.
(5) to an external radiation loss is low, it is possible to concentrating the power at a necessary position.
(6) containing a wide range of atmospheric pressure in the pressure range to generate a stable high-density plasma.
However, the conventional use of a microwave power of the plasma-generating device, using a waveguide as a microwave transmission line of the metal tube, having a microwave transmission circuit structure size is too large and expensive and problems such as difficult to work at low power.
Recently, in order to place of the conventional waveguide, there is provided a plasma stream generating device using a micro strip line method for making, using a microwave transmission line is a low power micro strip line (refer to Patent Document 2, 3 and Non-Patent Document 1, 2).
Fig. 15 shows the use of conventional micro strip line of the flow generating means is a perspective view of an example of a plasma.The device is made up of: a microwave input unit 13, disposed in the dielectric substrate 1 an end portion of one of the cross-section; tapered section 14, the dielectric substrate 1 toward the other one of the end portion is formed; gas passage 23, is provided in the interior of the dielectric substrate 1; with microwave power transmission of the micro strip line 11, is provided in one of the surface of the dielectric substrate 1; the ground conductor 12, the dielectric substrate 1 is covered on one side of the other; the plasma generating section 25, is placed in the micro strip line 11 and the ground conductor between 12; and nozzle 24, the discharge plasma.
In the plasma stream generating means, provided on the dielectric substrate 1 on the side of the gas from the two gas inlet port 22, 23 and passes through the gas passage 22 input, 23, 25 merges the plasma generating section, a nozzle 10 mm from the width of the dielectric substrate 1 to 24 ejects to the outside.
A microwave (2.45 GHz) power, through the dielectric substrate 1 by using a microwave coaxial connector 31 is introduced into the inside, and the micro strip line 11 and the ground conductor 12 transmission between, on the position of the plasma generating section 25 is concentrated in.As a result, plasma creation, and with the air flow from the nozzles ejects to the outside of the dielectric substrate 1 to 24.
On the other hand, in a plasma process, in order to improve the productivity, to have a large width can be carried out over a large area plasma flow through plasma processing and development of a strong demand, using a micro plasma creation means, due to its structure is a dielectric substrate, such as the common ground conductor, and arranging a micro strip line, thereby enabling a scaled up (refer to Patent Document 2), it is expected that future development.
Prior Art Document
Patent Document 1: Japanese Laid-Open Publication No.2003-109795
Patent Document 2: Japanese Laid-Open Publication No.2007-299720
Patent Document 3: Japanese Laid-Open Publication No.2008-282784
Non-Patent Document 1: Susanne Schemer,et.al., "An improved microstrip plasma for optical emission spectrometry of gaseous species", Spectrochimica Acta Part B: Atomic Spectroscopy,Vol.56,pp.1585-1596 (2003).
Non-Patent Document 2: Jaeho Kim,et.al., "Microwave-excited atmospheric-pressure plasma jets using a microstrip line", Applied Physics Letters,Vol.93,191505 (2008).
1. A microwave plasma processing apparatus, characterized in, is provided with:
The dielectric substrate;
A micro strip line, from one of the 1st surface of the dielectric substrate across to the other end of the end of the set, 1st surface of the dielectric substrate is either one of the front and back surfaces;
A ground conductor, the dielectric substrate of the 1st to 2nd surface of the one of the opposite face to the other end of the end of the spanning set;
Microwave input unit, provided at one end portion of the dielectric substrate, and is used to input to the micro strip line and the ground conductor between microwave;
A plasma generator, microwaves which are used to heat the plasma is generated from the microwave input unit for inputting a space, and provided on a micro strip line and the ground conductor;
The gas inlet opening, set on a grounded conductor or on the micro strip line, and for supplying gas to the plasma creation unit; and
The nozzle, for the creation of gas and is supplied to the plasma using a microwave generated plasma, from the other of the discharge end of the dielectric substrate.
2. A microwave plasma processing apparatus according to claim 1, characterized in,
The gas inlet opening than the diameter of the small cross-section of the shield wavelength determined by the gas input port.
3. A microwave plasma processing apparatus according to claim 1 or 2, characterized in,
1st 2nd surface of the dielectric substrate surface or has a slot, a micro strip line or a ground conductor plate embedded in the groove.
4. In accordance with claim 1-3 microwave plasma processing apparatus according to any one, characterized in,
A dielectric substrate having a tapered portion, the tapered portion is toward the other side of the dielectric substrate thickness across the end of a tapered shape.
5. In accordance with claim 1-4 microwave plasma processing apparatus according to any one, characterized in,
The ground conductor or a micro strip line is provided with two or more of the gas inlet opening, through gas fed through the input to each of the different gas species, the plasma discharge characteristics and plasma processing characteristics.
6. A microwave plasma processing apparatus according to claim 5, characterized in,
The ground conductor or a micro strip line is provided with two or more gas input port, at any one gas input port of a liquid material evaporation supply unit has.
7. According to any one of claim 1-6 microwave plasma processing apparatus, characterized in,
The microwave plasma processing apparatus includes:
2nd dielectric substrate, micro strip line is provided on the dielectric substrate are provided in contact with the surface;
2nd ground conductor, from the 2nd dielectric substrate is put across the end of one of the other end is provided;
2nd plasma generating portion, is provided in the space between the 2nd microwave strip line and a ground conductor;
2nd gas input port, a ground conductor provided in the 2nd, 2nd and used to supply gas to the plasma creation unit;
2nd gas supply means, gas input port for supplying gas to the 2nd; and
2nd nozzles, for the creation of the plasma is supplied to the 2nd gas and using a microwave generated plasma, 2nd dielectric substrate from the other of the ends of the discharge.
8. A microwave plasma processing apparatus, characterized in,
Claim 1-7 microwave plasma apparatus according to any one will, through a common dielectric substrate and the ground conductor, and is laterally arranged, so that the major axis length of plasma creation.
9. A microwave plasma processing apparatus, characterized in,
Claim 1-8 microwave plasma apparatus according to any one of, supplying a noble gas, reactive gas, or a mixed gas of rare gas and reactive gas, and in low-pressure or intermediate pressure or under high gas pressure plasma creation.
|参考情報 （研究プロジェクト等）||Innovative Plasma Processing Group, AIST|
『 Microwave plasma treatment apparatus 』に関するお問合せ
- 国立研究開発法人産業技術総合研究所 ベンチャー開発・技術移転センター
- URL: http://www.aist.go.jp/aist_j/collab/patent/patent/tlo.html
- Address: 〒305-8560 茨城県つくば市梅園1-1-1 中央第一
- TEL: 029-862-6158
- FAX: 029-862-6159