JP4423393B2 - Microplasma deposition method and apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for supplying a liquid raw material into a microplasma generator and performing microplasma deposition from the liquid raw material by performing reaction, decomposition or atomization by microplasma.

Conventionally, an inductively coupled microplasma generation method, a corona discharge type microplasma generation method, and the like have been developed. These microplasmas generate plasma inside the quartz tube or the injection needle by introducing gas into the inside of the quartz tube or medical injection needle and applying a high frequency from the outside via an induction coil or a mouth clip. And ejected from the tip.
Recently, material processing such as etching of a region of several hundred microns on a substrate and material deposition to a region of several hundred microns has been attempted using these (see, for example, Patent Document 1).

  Regarding the deposition of materials, a chemical vapor deposition method (CVD method) using a gas as a raw material for the deposition material is generally attempted. Recently, our research group has developed a wire spraying method in which a metal wire is inserted inside a quartz tube, and the wire is melted or evaporated by heat conduction from the plasma and induction heating by an induction coil to be ejected from the capillary tip (patent) Reference 2).

Thus, in the conventional method, it is possible to use only gas or metal wire as a raw material for deposition. However, if it becomes possible to introduce more liquid raw materials, more types of materials can be deposited with microplasma.
As a method for supplying liquid material into the microplasma, Ichiki et al. Introduced the liquid material through the liquid material supply nozzle from the direction perpendicular to the flow direction of the microplasma jet frame ejected from the tip of the microplasma generation nozzle. However, there is an example used for trace element analysis (see Non-Patent Document 1).
However, in this liquid material introduction method, the gas flow of the microplasma jet is disturbed, and the liquid material is scattered in various directions, achieving the deposition only in the microscopic area, which is a feature of deposition by microplasma. Is difficult.

The liquid sample supply unit used for normal ICP mass spectrometry is divided into a coaxial type in which the liquid sample feed pipe and the nebulizer gas pipe are coaxial, and a cross flow type in which both pipes are orthogonal. is there.
The principle of liquid sample introduction is explained by Bernoulli's theorem of fluid mechanics. In a normal ICP device, a liquid sample is generated by generating a negative pressure in the liquid sample feed pipe head by flowing a nebulizer gas at a high speed. Sucking.
However, with microplasma, the diameter of the nozzle that generates the plasma is very small, from a few microns to a few hundred microns, so it is impossible to flow gas at a speed that creates a negative pressure in the liquid sample feeding tube head. For this reason, liquid sample suction by the conventional method cannot be expected.
Therefore, it can be said that there is substantially no technique for performing microplasma deposition from a conventional liquid material.
JP 2003-328138 A Japanese Patent Application No. 2003-274612 “Plasma source science and technology” 12 (4) S16-S20 Nov 2003

The present invention aims to solve the above-mentioned problems, a system for efficiently atomizing and supplying a very small amount of solution raw material in microplasma, and using the microplasma from the solution raw material. Provided is a technique for depositing or depositing reaction products and formed fine particles on a substrate by CVD, thermal spraying, vapor deposition, or the like.
Specifically, a cross flow type micro nebulizer in which micro nozzles for liquid supply are arranged so as to be orthogonal to the plasma gas supply line is provided, and an organic liquid sample or the like is obtained using this micro nebulizer (plasma deposition apparatus). Provided is a technique for depositing (depositing or adhering) materials such as reaction products and fine particles on a substrate placed downstream of the microplasma by supplying it into the microplasma for reaction, decomposition or atomization. Also provided is a microplasma deposition technique in which a solution such as a colloid in which a powder material is dispersed in a liquid is supplied into a microplasma, and the material is vapor-deposited and sprayed onto a substrate disposed downstream.

In order to efficiently evaporate, dissociate, ionize, or melt the surface of the fine particles dispersed in the solution supplied to the microplasma, it is necessary to increase the residence time in the plasma. It is desirable that the gas flow rate that is closely related to the residence time can be controlled to the lowest possible region.
Therefore, the invention of this application has been made to solve the above-described problems, and an extremely small amount of liquid material is supplied from the upstream side of the nozzle for generating microplasma, and the diameter of the outlet is from several microns to several tens. A liquid material supply system that can be supplied from a micron nozzle by a gas pressure application method, efficiently atomized with a plasma gas flowing perpendicular to the liquid material supply nozzle, and supplied into the microplasma. is there. Furthermore, the present system is used to provide a deposition method and apparatus such as a CVD method, a vapor deposition method, and a thermal spray method using a liquid raw material.

Specifically, the present invention aims to solve the above problems,
1) A liquid is supplied upstream or in the middle of the microplasma gas supply line so as to be substantially orthogonal to the line, and the liquid is reacted, decomposed or atomized by microplasma, and reacted on a substrate installed downstream of the microplasma. A microplasma deposition method comprising depositing a product or fine particles.
2) In the upstream or midway of the microplasma gas supply line, a liquid is supplied so as to be substantially orthogonal to the line and reacted, decomposed or atomized by the microplasma, while the solid raw material is at or near the microplasma source. The solid raw material is melted and vaporized, or the gaseous raw material is supplied into the microplasma, and the reaction product comprising the material supplied from the liquid and the material supplied from the solid raw material and / or the gaseous raw material A microplasma deposition method comprising depositing an object or fine particles on a substrate placed downstream of the microplasma.
3) The reaction product or fine particles are deposited on the surface of a wire, such as metal or metal oxide, which is a substrate provided downstream of the microplasma gas supply line, or on the inner wall surface of the fine tube, Microplasma deposition method.
4) The microplasma deposition method according to any one of 1) to 3), wherein carbon nanotubes are deposited using a ferrocene ethanol solution.
5) The microplasma deposition method according to any one of 1) to 4), wherein a deposit region is prepared by adjusting a tip inner diameter of a capillary of a microplasma supply line.
6) The microplasma according to any one of 1) to 5), wherein a line pattern or a dot pattern is formed on the substrate by moving the substrate in a two-dimensional direction during the microplasma deposition. Deposition method.
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Furthermore, the present invention provides
7) From a glass tube or a quartz tube having a taper shape in which the air outlet is tapered toward the air outlet having a diameter of 1 μm to 50 μm, which is installed upstream or in the middle of the micro plasma gas supply pipe so as to be substantially orthogonal to the air supply pipe. A microplasma deposition apparatus, comprising: a liquid supply nozzle, and a substrate for depositing reaction products or fine particles disposed downstream of the microplasma gas supply pipe.
8) The microplasma deposition apparatus according to 6), wherein the liquid supply nozzle has a structure in which a glass tube or a quartz tube is bonded to a metal tube such as stainless steel with an epoxy adhesive.
9) Use a chemical-resistant tube as the liquid feed tube, insert the metal tube of the liquid supply nozzle into the tube, and tighten the nut, back or front ferrule to press-bond the metal tube of the liquid supply nozzle in the tube The microplasma deposition apparatus according to 7) or 8), characterized by comprising the above structure.
10) The microplasma deposition apparatus according to any one of 7) to 9), wherein the tip of the liquid supply nozzle is disposed at the center of the microplasma gas supply pipe.
11) The microplasma deposition apparatus according to 9) or 10), wherein the liquid injected into the tube is ejected from a liquid supply nozzle tip by applying a gas pressure from the other end of the tube.
12) An inner tube is further inserted into the microplasma gas supply pipe, and the outlet of the inner pipe is installed immediately before the outlet of the liquid supply nozzle, and the microplasma gas is supplied to the inner pipe so that the gas is supplied at high speed. 7. The microplasma deposition apparatus according to any one of 7) to 11), wherein the liquid supply nozzle is sprayed.
13) A wire or a fine tube made of a metal, metal oxide or the like as a substrate is arranged downstream of the microplasma gas supply tube, and reaction products or fine particles are deposited on the wire surface or the inner wall surface of the fine tube. The microplasma deposition apparatus according to any one of) to 12).
14) The microplasma according to any one of 7) to 13), wherein a device for supplying a solid material to melt and vaporize or a gas material supply device is provided at or near the microplasma generation source. Deposition device.
15) The microplasma deposition apparatus according to 14), wherein a metal wire serving as a solid material or a gas material supply device is disposed in a capillary for generating microplasma.
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As described above, the liquid raw material can be introduced from the upstream side of the microplasma generating nozzle. Therefore, the flow direction of the particles generated by the CVD process or the PCVD process or the microparticles in the colloidal solution is determined by the microplasma generating nozzle. It is possible to control by controlling the internal shape, and there is an excellent effect that it is possible to deposit only in a minute region.
The present invention can also realize micro-plasma CVD from a liquid source, PCVD using a solid source, or a thermal spraying process or vapor deposition without reaction in plasma. The microplasma deposition method used in the present invention includes all of them.

Further, by introducing the liquid material from the upstream of the microplasma generating nozzle, it is possible to lengthen the time during which the liquid material passes through the microplasma, that is, the residence time. This leads to efficient evaporation, dissociation, ionization, and reaction of the liquid source in the plasma, thereby achieving an efficient microplasma CVD process from the liquid source and further a microplasma CVD process using the solid source. It becomes possible.
In addition, when the liquid source is a colloidal solution in which fine particles are dispersed in a liquid, there is sufficient residence time to sufficiently melt the fine particle surface in the solution. Can be achieved.
As described above, the method and apparatus of the present invention have an unprecedented excellent effect.

The microplasma deposition apparatus used in the method of the present invention is installed upstream or in the middle of the microplasma gas supply pipe so as to be substantially orthogonal to the supply pipe. In this case, the liquid supply nozzle uses a glass tube or a quartz tube having a tapered shape in which the air outlet tapers toward the air outlet having a diameter of 1 μm to 50 μm. This can be produced, for example, by subjecting a glass tube or a quartz tube having an outer diameter of 1 mm to heat tension. The substrate on which reaction products or fine particles are deposited is installed downstream of the microplasma gas supply pipe.
In particular, the liquid supply nozzle may have a structure in which a glass tube or a quartz tube is bonded to a metal tube such as stainless steel with an epoxy adhesive. Specifically, for example, the liquid supply nozzle can be connected to a metal tube such as stainless steel having an inner diameter of 1/4 inch with an epoxy adhesive to form a liquid supply nozzle.

Further, as the liquid feeding tube, it is preferable to use a chemical resistant tube (for example, Tygon tube: trade name, the same applies hereinafter). The metal pipe of the liquid supply nozzle is inserted into this tube. The nut, the back or the front ferrule is tightened, and the metal pipe of the liquid supply nozzle is pressed and joined in the tube. This enables tight bonding.
Specifically, for example, a Tygon tube having an inner diameter of 1/4 is used as the liquid feeding pipe, the metal pipe part of the liquid supply nozzle unit is inserted into the Tygon tube, and a commercially available 1/4 inch nut, back and front ferrule are attached. Compression bonding can be performed by tightening.

In particular, it is desirable to arrange the tip of the liquid supply nozzle at the center of the microplasma gas supply pipe. For example, the liquid supply nozzle device is fastened and fixed to a commercially available 1/4 inch union tee with a nut, and the tip of the nozzle is arranged at the center of the gas feed tube to form a cross flow type nebulizer (liquid atomizer). Can do.
Then, the liquid injected into the tube is ejected from the tip of the liquid supply nozzle by applying a gas pressure from the other end of the tube.

In the microplasma deposition apparatus of the present invention, an inner pipe is further inserted into the microplasma gas supply pipe, and the outlet of the inner pipe is installed immediately before the outlet of the liquid supply nozzle. A plasma gas can be supplied and the liquid supply nozzle can be sprayed at a high speed.
Specifically, for example, a gas supply pipe of 1/8 inch is inserted immediately before the outlet of a liquid supply nozzle built in a 1/4 inch union tee, and gas is blown to the nozzle outlet at a high speed. The liquid sample can be efficiently atomized and supplied into the plasma.

In the microplasma deposition apparatus of the present invention, a wire or a micropipe such as a metal or metal oxide as a substrate is disposed downstream of a microplasma gas supply pipe, and reaction products or fine particles are placed on the wire surface or the inner wall of the micropipe. Deposit can be made.
Further, according to the present invention, it is possible to synthesize carbon nanotubes from a ferrocene ethanol solution and deposit the carbon nanotubes on a substrate disposed downstream of the generated microplasma.

  The features of the present invention will be specifically described below with reference to the drawings. In addition, the following description is for making an understanding of this invention easy, and is not restrict | limited to this. That is, modifications, embodiments, and other examples based on the technical idea of the present invention are included in the present invention.

FIG. 1 shows a schematic diagram of a liquid sample supply nozzle used in the present invention. This is produced by pulling a glass and quartz capillary having an outer diameter of 1.0 mm on a 1/8 inch metal tube 1, and a nozzle 2 having an inner diameter of 1 to 50 μm at the tip is connected to an epoxy adhesive 3. It was joined with. The tip diameter, shape, etc. of the nozzle can be controlled by adjusting the tension processing conditions.
FIG. 2 shows a specific example of a liquid supply apparatus for microplasma using the nozzle shown in FIG. These all use and combine a commercially available (Tygon) tube 4, union tee 5, nut 7, back and front ferrule 6. A stainless steel metal tube 1 (outer diameter 1/8 inch) of the liquid supply nozzle 2 shown in FIG. 1 was inserted into a tube 4 having an outer diameter of 1/4 and an inner diameter of 1/8 inch, which is a liquid feed pipe.

As shown in FIG. 2, this is inserted into a 1/4 inch union tee 5 and the front / back ferrule 6 and nut 7 are tightened to compress the tube 4 and the stainless steel metal tube 1 of the liquid supply nozzle 2. Joined.
The other end of the tube 4 was connected to a gas cylinder equipped with a gas pressure regulator for applying a liquid sample. The above-described compression bonding of the metal tube 1 and the equipment shown in the tube 4 can prevent leakage of the liquid sample from the insertion portion of the liquid supply nozzle 2 into the tube 4 and can be applied to eject the sample when supplying the liquid sample. This makes it possible to prevent the nozzle from being detached when the gas pressure is applied.

The gas feed pipe of the union tee 5 orthogonal to the liquid supply nozzle 2 is a plasma gas supply pipe, one side is connected to a gas cylinder (not shown) through a 1/4 inch metal pipe connected by a ferrule and a nut, and the other side Is connected to a microplasma generator (not shown). Existing equipment can be used for the plasma gas supply and the microplasma generator.
In this system, the plasma gas also plays the role of the nebulizer gas, and the liquid leaked from the tip of the liquid supply nozzle 2 due to the gas pressure application is atomized by the plasma gas flowing in the orthogonal pipe, and is microscopically combined with the plasma gas. Supplied into the plasma generator.

In the present invention, the apparatus shown in FIG. 3 can be provided for the purpose of improving the spray efficiency of the liquid sample. 3 that are common to FIG. 2 use the same reference numerals. 1/8 inch metal tube 8 is used for the plasma gas supply pipe, and it is inserted into a 1/4 inch union tee via a commercially available bore through reducer 9 and connected to it. Is arranged immediately before the tip of the liquid supply nozzle.
By using this 1/8 inch gas supply pipe 8, the plasma gas supply rate is simply four times that of the 1/4 inch case, so that the liquid is supplied immediately after blowing from the supply pipe. Since the sample leaked from the tip of the sample supply nozzle can be sprayed, the liquid sample can be atomized with high efficiency.

Furthermore, the present invention provides a device for supplying and melting and vaporizing a solid material or a gas material supply device at or near the microplasma generation source, and melting or vaporizing the solid material or gas in the microplasma. A raw material is supplied and further supplied to the liquid sample supply nozzle together with the microplasma, and a reaction product or fine particles comprising the material supplied from the liquid and the material supplied from the solid raw material and / or the gas raw material Can be deposited on a substrate placed downstream of the microplasma.
A technique for forming a reaction product or fine particles using a gas, liquid, or solid as a starting material can be referred to as a plasma CVD method or a plasma PCVD method.
FIG. 4 shows a microplasma PCVD method in which, for example, a metal wire 10 serving as a solid raw material is provided in a quartz capillary 11 for generating microplasma, a copper coil 13 is disposed around it, and one end thereof is coupled to a high-frequency power source 12. An example of the apparatus to be used is shown.
The solid material is melted and atomized (vaporized) by the plasma, and is supplied along with the plasma gas toward the substrate. Although not shown, a tube for introducing a reactive gas can be installed in the microplasma generating capillary 11. These can be used together, that is, the solid material and the gas material can be simultaneously supplied into the microplasma gas.

Next, an example of deposition by microplasma from a liquid material using the liquid supply system will be described.
A capillary made of quartz having a taper shape with an inner diameter from 700 μm to 50 μm toward the tip was used as the capillary for generating microplasma. Plasma gas (Ar) was supplied into the capillary at a flow rate of 30 ccm, and a 20 W high frequency (450 MHz) was applied to the induction coil wound around the capillary to generate microplasma.
Ethanol was supplied into the microplasma under the condition of a gas pressure of 0.1 MPa through a liquid sample supply nozzle having a tip inner diameter of 10 μm using the apparatus (system) shown in FIG. The vapor deposition substrate was set 500 μm downstream from the tip of the plasma generating nozzle.

FIG. 5 shows an optical micrograph of the material deposited only in the 50 μm region on the substrate. This material was composed of spherical particles having a diameter of 10 to 50 nm as seen in the scanning electron micrograph of FIG. 3 in FIG. 5 shows a transmission electron micrograph of the spherical particles. As a result of analyzing them with a transmission electron microscope and transmission electron beam diffraction, it was revealed that they were crystalline spherical graphite (see 4 in FIG. 5).
Thus, by supplying ethanol into the microplasma generated in the capillary using the liquid sample supply system provided in the present invention, crystalline graphite is easily synthesized, and the substrate is several tens of μm. It is possible to deposit in the region.

The deposition area can be controlled from 1 μm to 50 mm by further increasing the inner diameter of the tip of the capillary for microplasma generation and vice versa, and further controlling the distance between the tip of the plasma generation nozzle and the evaporation substrate. Is possible.
Further, by moving the vapor deposition substrate in a two-dimensional direction during processing, it becomes possible to draw a line pattern, a dot pattern, and the like on the substrate. The system can also be used to synthesize and deposit carbon nanotubes on a substrate.

  In this implementation, a ferrocene ethanol solution was supplied into microplasma generated under the same conditions as described above. In this case as well, as in the example shown in FIG. 5, the film was deposited only in the 50 μm region on the substrate. However, it can be seen from the scanning electron microscope observation shown in FIG. This is presumably because carbon derived from ethanol and iron derived from ferrocene reacted in microplasma, and carbon nanotubes were generated by the catalytic action of iron.

  The present invention can realize a microplasma CVD from a liquid source, and further a microplasma PCVD by supplying a liquid source into the microplasma, decomposing / reacting or atomizing them, and depositing and depositing them as solids. It is. In addition, a thermal spraying process without reaction in plasma can be realized. In this method, a solution in which fine particles of metal, metal oxide or the like are dispersed in a liquid is supplied into the microplasma through the liquid supply system of the present invention. The solvent evaporates and decomposes in the plasma, and the fine particles melt when the surface comes into contact with the plasma. These fine particles ejected from the nozzle for generating microplasma are deposited on the substrate or the fine particles already deposited. The present system can be applied to such a thermal spraying process.

It is the schematic of a liquid sample supply nozzle. It is explanatory drawing which shows the specific example of the liquid supply apparatus in microplasma. It is explanatory drawing which shows the other specific example of the liquid supply apparatus in microplasma. It is explanatory drawing of the apparatus which supplies a solid raw material into microplasma. 1 in the figure shows an optical micrograph of the deposited material, 2 in the figure is a spherical particle observed in the scanning electron micrograph, 3 in the figure is a transmission electron micrograph of the spherical particle, 4 in FIG. Is a transmission electron diffraction pattern obtained from spherical particles. It is a scanning electron micrograph which shows that the carbon nanotube was produced | generated and deposited.

Explanation of symbols

1. 1. Metal tube Nozzle 3. Adhesive 4. Tube 5. Union tea Front / back ferrule Nut 8. Metal tube 9. Bored through ready user10. Raw metal wire 11. Capillary for generating microplasma 12. High frequency power supply 13. Copper coil

Claims (15)

  In the upstream or midway of the microplasma gas supply line, a liquid is supplied so as to be substantially perpendicular to the line, and the liquid is reacted, decomposed or atomized by microplasma, and a reaction product is formed on a substrate installed downstream of the microplasma. Alternatively, a microplasma deposition method comprising depositing fine particles.   In the upstream or midway of the microplasma gas supply line, liquid is supplied so as to be almost perpendicular to the line and reacted, decomposed or atomized by the microplasma, while the solid material is supplied to the microplasma generation source or its vicinity. Then, the solid raw material is melted and vaporized, or a gas raw material is supplied into the microplasma, and a reaction product comprising the material supplied from the liquid and the material supplied from the solid raw material and / or the gas raw material or A microplasma deposition method comprising depositing fine particles on a substrate placed downstream of a microplasma.   3. The micro of claim 1 or 2, wherein the reaction product or fine particles are deposited on the surface of a wire, such as metal or metal oxide, which is a substrate provided downstream of the microplasma gas supply line, or on the inner wall surface of the fine tube. Plasma deposition method.   The microplasma deposition method according to claim 1, wherein carbon nanotubes are deposited using a ferrocene ethanol solution.   The microplasma deposition method according to any one of claims 1 to 4, wherein the deposit region is prepared by adjusting a tip inner diameter of a capillary of the microplasma supply line.   The microplasma deposition according to any one of claims 1 to 5, wherein a line pattern or a dot pattern is formed on the substrate by moving the substrate in a two-dimensional direction during the microplasma deposition. Method.   A liquid made of a glass tube or a quartz tube having a tapered shape, which is installed upstream or in the middle of the microplasma gas supply tube so as to be substantially orthogonal to the supply tube, and whose outlet is tapered toward the outlet having a diameter of 1 μm to 50 μm. A microplasma deposition apparatus comprising: a supply nozzle; and a substrate for depositing reaction products or fine particles disposed downstream of a microplasma gas supply pipe.   8. The microplasma deposition apparatus according to claim 7, wherein the liquid supply nozzle has a structure in which a glass tube or a quartz tube is bonded to a metal tube such as stainless steel with an epoxy adhesive.   A structure in which a chemical-resistant tube is used as a liquid feed pipe, the metal pipe of the liquid supply nozzle is inserted into the tube, and the nut, back or front ferrule is tightened to press-join the metal pipe of the liquid supply nozzle in the tube The microplasma deposition apparatus according to claim 7, wherein the microplasma deposition apparatus is provided. 10. The microplasma deposition apparatus according to claim 7, wherein a tip of the liquid supply nozzle is disposed at the center of the microplasma gas supply pipe.   The microplasma deposition apparatus according to claim 9 or 10, wherein the liquid injected into the tube is ejected from a tip of a liquid supply nozzle by applying a gas pressure from the other end of the tube.   An inner tube is further inserted into the microplasma gas supply pipe, and an outlet of the inner pipe is installed immediately before the outlet of the liquid supply nozzle. Microplasma gas is supplied to the inner pipe, and the gas is supplied at a high speed. The microplasma deposition apparatus according to claim 7, wherein a liquid supply nozzle is sprayed.   8. A wire or a fine tube made of metal, metal oxide or the like as a substrate is arranged downstream of the microplasma gas supply tube, and reaction products or fine particles are deposited on the wire surface or the inner wall surface of the fine tube. The microplasma deposition apparatus in any one of -12.   The microplasma deposition according to any one of claims 7 to 13, wherein a device for supplying and melting and vaporizing a solid material or a gas material supply device is provided at or near the microplasma generation source. apparatus. 15. The microplasma deposition apparatus according to claim 14, wherein a metal wire serving as a solid material is disposed in a capillary for generating microplasma or a gas material supply device is disposed.