JP2008198583A - Plasma generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma generator capable of stably generating and maintaining high-density and high-energy-efficiency inductively-coupled microplasma, and of executing a process using the plasma. <P>SOLUTION: This plasma generator equipped with an inductively-coupled plasma generation coil 9 around an insulator tube, and also equipped with electrodes 3 and 4 for generating dielectric barrier discharge inside and outside of the tube is composed. By connecting the metal electrodes and a coil part to various power sources through cables, inductively-coupled plasma by dielectric barrier discharge, in particular, microplasma having a size not larger than 1 mm which becomes difficult to stably maintain by miniaturization is generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-density microplasma generator and a material processing application.

  At present, plasma material processing technology is used in many fields such as material development and production technology, and its importance is expected to increase in the future.

  For example, taking the processing of electronic devices such as semiconductors as an example, it is a well-known fact that plasma processing technology is indispensable in the processing of such electronic devices. Such electronic devices have been increasingly miniaturized recently, and spatial and local processing on a micrometer or nanometer scale is required. Therefore, there is a demand for microplasma whose cross-sectional size is on the order of micrometers to nanometers. A plasma (microplasma) generator has already been proposed to meet such demands. (See JP-A-8-298198 and JP-A-8-306499).

  However, many of the proposed plasma generators have to set a high-pressure vessel or plasma electrode and a material to be processed with plasma in the vessel, further transport the material into the vessel, A material transport mechanism for taking out the material in the inside is also required, and as a result, the plasma generation device itself including the container is increased in size, complexity, and cost. In order to solve such a problem, a part of the inventor previously proposed a novel inductively coupled plasma (ICP) plasma generator capable of generating a high-density plasma (special feature). Application No. 2001-76877 and Japanese Patent Application No. 200012084).

  This apparatus is a thermoelectron-assisted inductively coupled microplasma generator that assists discharge by supplying thermoelectrons from induction-heated metal. With the help of thermoelectrons, the ratio of the wall (surface) that becomes the loss / disappearance part of the plasma is usually larger than the bulk part of the plasma, making it difficult to generate plasma. This facilitates the generation and maintenance of microplasma. To date, microplasma with a minimum discharge space of about 20 μm inside the tube has been successfully generated, and its plasma diagnosis has been applied to maskless film formation and etching in local regions. This plasma device is light and small, very easy to operate with human hands, low cost, and can be brought to the material to be processed and processed, and it has extremely excellent characteristics in terms of operability. Have. Moreover, such a plasma generator can be applied to environmental applications (such as decomposition of harmful substances) in addition to material processes (for example, material processing, material melting, substance synthesis, etc.).

  However, although the thermal electron source is successfully provided for miniaturization to the size of several tens of μm for the first time, the applied power is also used for induction heating of the metal, and thus energy loss cannot be ignored. In addition, problems such as difficulty in generating a lower temperature and higher density plasma due to an increase in the plasma gas temperature due to the high temperature of the electrode remain difficult, and development of new technologies is desired. Yes.

  Under the background as described above, the present invention provides a microplasma generator that can stably generate and maintain high-density, high-energy-efficiency inductively coupled microplasma and that can perform processing using plasma. The purpose is to provide.

  Dielectric Barrier Discharge Assisted Inductive Coupled Type Using Dielectric Barrier Discharge (DBD) as an Auxiliary Electron Supply Source as an Auxiliary Electron Source for Realizing Miniaturization (Microplasmaization) of Inductively Coupled Plasma It is characterized by the ability to generate microplasma and, in addition, easily bring it into any environment by connecting the plasma torch with a flexible tube.

  A plasma generator according to the present invention includes a dielectric cylindrical dielectric plasma torch, plasma gas supply means for supplying a plasma gas into the torch, and a high frequency for generating a dielectric barrier discharge by supplying high frequency power. A power source, a dielectric barrier discharge electrode material disposed so as to be located in or near the plasma generation region in the torch, a dielectric barrier discharge electrode disposed outside the torch, around the torch It is mainly composed of a coil for inductively coupled plasma generation and a high frequency power source for inductively coupled plasma generation.

  Furthermore, these plasma generators can connect a plasma gas source and a plasma torch with a flexible tube. A cable connecting the high-frequency power source and the electrode and a cable connecting the ground and the electrode are passed through the tube, while a cable connecting the high-frequency power source and the electrode inside the torch, and a cable connecting the ground and the electrode outside the torch.

  As described above, according to the present invention, high-density microplasma can be generated and maintained easily and stably in various environments such as in liquid, underground, and living organisms. As a result, various material processing using microplasma is possible under various environments.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows one schematic example of an embodiment of the low-temperature microplasma generator of the present invention.

  A dielectric cylindrical plasma torch (1) having an inner diameter of 1 to 10 μm, a plasma gas supply unit (7) for supplying plasma gas into the torch, and a high frequency power between the electrodes A high frequency power source (8) for generating body barrier discharge, an electrode material for dielectric barrier discharge (3) disposed so as to be located in or near the plasma generation region in the torch, Dielectric barrier discharge electrode material (4) disposed outside the torch, inductively coupled coil (9) wound outside the torch, and a high frequency power source for generating inductively coupled plasma 10)), wherein the plasma gas source and the plasma torch are connected by a flexible tube (2). The cable connecting the high frequency power source and the electrode (5) and the cable connecting the ground and the electrode (6) are passed through the tube, while the cable (5) connecting the frequency power source and the electrode in the torch. A cable (6) connecting the ground and the electrode was arranged outside the torch.

  Microplasma can be generated by supplying high-frequency power to the above apparatus (FIG. 1).

  An example of a photograph of the generated plasma is shown in FIG. The plasma generation conditions in this case are: plasma gas Ar (flow rate: 1 slm), frequency for DBD generation, applied voltage is 10 kHz, 2.2 kVp-p, frequency for ICMP generation is 450 MHz, and input power is 4 to 10 W. With increasing input power, the plasma was larger and the emission was brighter.

  As an example of plasma material processing (material synthesis, deposition, etching, surface treatment, etc.) using this plasma, polycarbonate surface treatment was performed. As the plasma gas, He gas was used, and the contact angle of water droplets was improved to half or less (hydrophilization) in a treatment at 5 W for 30 seconds in an atmospheric environment. This is an example of application, and it is needless to say that it can be applied to general material processes such as material synthesis, deposition, and etching.

It is the figure which showed one schematic example of the microplasma generator of this invention. Change in shape of microplasma generated by the plasma generator of the present invention under atmospheric pressure depending on power input conditions (experimental conditions; torch inner diameter 500 μm, electrode tungsten wire diameter 100 μm, plasma generation conditions are plasma gas Ar (flow rate: 1 slm) , DBD generation frequency, applied voltage is 10 kHz, 2.2 kVp-p, inductively coupled plasma generation frequency is 450 MHz, input power is 4-10 W. It is an example of the result of what hydrophilized the surface by surface treatment with polycarbonate using the microplasma generator of the present invention. The right shows the state of water droplets on the surface before treatment, and the left shows the state of water droplets on the surface after treatment.

Explanation of symbols

(1) ... Plasma torch (2) ... Flexible tube (3) ... Electrode material for dielectric barrier discharge (4) ... Electrode material for dielectric barrier discharge (5) ... High frequency Cable connecting power supply and electrode (6) ... Cable connecting ground and electrode (7) ... Plasma gas supply unit (8) ... High frequency power supply for dielectric barrier discharge (9) ... Inductive coupling type Plasma generating coil (10): Inductively coupled plasma power supply P: Plasma generating part S: Adhesive

Claims (4)

  A process plasma generator comprising an inductively coupled plasma generating coil around a dielectric tube, and an electrode for generating a dielectric barrier discharge inside and outside the tube.   The process plasma generator according to claim 1, wherein the tube made of a dielectric material such as the quartz tube according to claim 1 has an inner diameter of 10 mm to 10 µm.   A plasma generator comprising the process plasma generating coil and electrode device according to claim 1 at the tip of a flexible tube for introducing a plasma source gas and in the vicinity of the tip.   A material synthesis, deposition, etching, and surface treatment process method using the process plasma generator according to claim 1, 2 or 3.

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