JP5004088B2 - Processing method and apparatus using modulated microplasma - Google Patents

Description

  The present invention relates to a microplasma processing method and apparatus for depositing material on various kinds of materials regardless of organic and inorganic using high-frequency microplasma, and particularly to a plasma generating capillary or plasma generator. The present invention relates to a microplasma processing method and apparatus using a nozzle for use.

In recent years, a technique for depositing different materials on the surface of a material such as a substrate using plasma generated under atmospheric pressure, so-called atmospheric pressure plasma, has been developed.
In particular, material processing technology in the atmosphere using microplasma with a diameter of the order of micrometers has been developed in recent years because of the small size of the device and good operability.
The present inventors have already made some proposals regarding the local material deposition technique in the atmosphere using microplasma.

The technique described in Patent Document 1 is a technique related to the development of a local material deposition apparatus using a nozzle type high-frequency microplasma generator (hereinafter, a tube having a narrowed tip is referred to as a “nozzle” On the other hand, a straight pipe is referred to as a “thin tube”.) While supplying an inert gas such as argon into an insulating nozzle having an inner diameter of several mm or less, a high frequency is continuously applied to an electrode installed around the nozzle. It is possible to generate plasma stably in the atmosphere only by supplying the air. The source material that can be introduced into the plasma is only gas species, but it has good crystallinity only in the local region on the non-heated material by chemical vapor deposition (hereinafter referred to as “CVD method”). This is an apparatus capable of growing and depositing carbon-based materials.
However, the technology that can supply only gas species as a raw material as described above may have the following technical limitations.
When considering a process in the atmosphere that does not use any vacuum exhaust system such as gas, it is not preferable to use a gas raw material that is harmful to the human body and the environment. In a normal metal or metal compound thin film manufacturing process, a toxic gas such as an organometallic gas is used, so that the types of materials that can be deposited by the technique described in Patent Document 1 are necessarily limited.

  As means for improving this problem, the present inventors have proposed new technologies in Patent Documents 2 and 3. These techniques use a metal wire as a main raw material. This technology also uses a narrow tube or nozzle type high-frequency microplasma generator, but a metal wire as a raw material is inserted in advance into the narrow tube or nozzle, and an inert gas or a reactive gas that can be handled in the atmosphere is allowed to flow. A voltage as shown in FIG. 1 is continuously applied to the electrodes installed around the narrow tube or nozzle to continuously generate a high-frequency plasma, and the metal wire is evaporated by heat conduction or high-frequency heating from the plasma. This is a technique for condensing and solidifying the generated gas phase and droplets in a downstream area of a nozzle or a thin tube and depositing the material on a substrate or the like installed downstream. In FIG. 1, (a) shows an applied voltage waveform, and (b) shows a high-frequency output waveform.

The technique described in Patent Document 2 is based on a technique related to atmospheric pressure plasma generation in a nozzle having an inner diameter of 50 μm or less, and the generation technique, onto a low melting point substrate having a melting point of 500 ° C. or less. The present invention relates to a technique for depositing a metal or a metal compound material in a dot shape of 100 μm and a line shape of 5 to 50 μm in width.
The technique described in Patent Document 3, by utilizing the capillary hundreds [mu] m 2 on any type of ^substrate, more in techniques for depositing metal or metal compound as a thin film to several cm ² or more large area is there.
However, the techniques described in Patent Documents 2 and 3 have the following technical limitations.

  First, there is a limit to the nozzle size that can be used to generate plasma. In the plasma generation technique described in Patent Document 2, generation in a nozzle having an inner diameter of about 20 μm is the limit, and plasma generation in a smaller size nozzle is impossible. In this technique, a nozzle having an inner diameter of 100 μm or less is produced by subjecting a quartz straight pipe having an inner diameter of about 300 to 800 μm to heat tension processing. In this manufacturing process, it is possible to manufacture an ultrafine nozzle with an inner diameter of several μm at the tip of the nozzle. However, with an ultrafine nozzle having an inner diameter of about 20 μm or less, the tube wall is very thin and heat resistance deteriorates. Therefore, the tip portion is easily damaged when plasma is generated. That is, in the atmospheric pressure plasma generation method described in Patent Document 2, a nozzle having a tube wall thickness of a certain thickness or more is necessary, and this is possible in a nozzle having an inner diameter of 20 μm or more, but in an ultrafine nozzle having an inner diameter of several μm. Plasma generation at is impossible.

  Furthermore, in the techniques described in Patent Documents 2 and 3, the types of wires that can be used as raw materials are limited. Deposition from low vapor pressure wires such as tungsten and molybdenum as described in the examples in these documents is possible, but high vapor pressure, ie low melting point materials such as magnesium, tin, indium It is difficult to deposit material from wires such as. When these low melting point material wires are inserted into a thin tube or nozzle and plasma generation is attempted, the insertion wire melts and is cut into several pieces at the moment when the plasma is generated, and the cut pieces are spheroidized by surface tension. That is, although it is not impossible to efficiently deposit on the substrate, the selection range of appropriate conditions for that purpose is narrow, and a very skillful technique is required.

The same can be seen in the case of noble metal materials. If the gas flow rate in the narrow tube or nozzle or the input energy of the applied high frequency is set to an appropriate value by the methods described in Patent Documents 2 and 3, deposition on the substrate installed downstream of the narrow tube or nozzle outlet is not possible. However, since the width of the appropriate range is extremely narrow, a great deal of experience in the deposition technique is required for performing the process.
JP 2003-328138 A JP-A-2005-262111 Japanese Patent Application No. 2006-225695 JP 2006-274290 A

The present invention has been made in view of the circumstances as described above, and is a novel material deposition that improves the above-mentioned problems when using a thin tube or nozzle having an inner diameter of several millimeters as a high-frequency microplasma generator. It is an object of the present invention to provide a method and an apparatus for carrying out the method.
That is, in the technical field for depositing material only on a region of only a few μm on the surface of a material such as a substrate, it is considered essential to use an ultrafine tube or ultrafine nozzle having an inner diameter of about several μm. . To that end, it is essential to develop a method for generating plasma with a low gas temperature, and to develop a technique for preventing damage to the wall of the ultrafine nozzle tube due to heat from the plasma.
In addition, in the thin film production process using the above ultrafine plasma, when using a low melting point material wire and a noble metal wire as a raw material, in order to prevent instantaneous melting of the raw material wire, shredding in a thin tube or nozzle, It is essential to develop a plasma generation method that has properties different from those of conventional plasma.

  As a result of intensive studies to achieve the above object, the inventors have applied a high frequency applied to generate plasma in the generation of a so-called capillary tube or nozzle type high frequency microplasma generated in a nozzle having a diameter of several millimeters or less. The present inventors have found that the above problem can be solved by modulating the voltage periodically or irregularly and generating plasma intermittently.

The present invention has been completed based on these findings, and is as follows.
(1) A high frequency plasma is generated in a plasma generating capillary or a plasma generating nozzle by applying a high frequency voltage, the generated plasma is irradiated toward a substrate to be processed, and a thin film is deposited on the substrate. A plasma processing method,
As a raw material, using a low melting point wire or a noble metal wire arranged in the narrow tube or nozzle,
A microplasma processing method, wherein plasma is generated intermittently by modulating the high-frequency voltage.
(2) The microplasma processing method according to (1), wherein a voltage waveform applied for the modulation is any one of a rectangular waveform, a triangular waveform, and a sine waveform.
(3) The microplasma processing method according to (2), wherein the voltage waveform applied for the modulation has a constant period or an indefinite period.
(4) The microplasma processing method according to any one of (1) to (3), wherein an inert gas is introduced into the narrow tube or the nozzle.
(5) A thin tube for plasma generation or a nozzle for plasma generation, a high-frequency application electrode for generating plasma in the thin tube or nozzle, a high-frequency power source for plasma generation for supplying a high-frequency voltage to the electrode, a support for a substrate to be processed, And a microplasma processing apparatus for depositing a thin film on the substrate, comprising at least means for irradiating the generated plasma toward the substrate to be processed,
While placing the low melting point wire or noble metal wire as a raw material in the narrow tube or nozzle,
A microplasma processing apparatus comprising means for intermittently generating plasma by modulating the high-frequency voltage.
(6) The microplasma processing apparatus according to (5), further comprising means for applying a voltage having a rectangular, triangular, or sine waveform for the modulation.
(7) The microplasma processing apparatus according to (5), further comprising means for applying a voltage having a waveform having a constant period or an indefinite period for the modulation.
( 8 ) The microplasma processing apparatus according to any one of the above (5) to (7), characterized by having means for introducing an inert gas into the narrow tube or nozzle.

  According to the method and apparatus of the present invention, plasma is generated intermittently, so that a thin film can be deposited even on a material having a low melting point. In addition, even when an ultrafine tube or an ultrafine nozzle having an inner diameter of 20 μm or less is used as a plasma generating thin tube, it is possible to deposit a thin film without damaging the tip portion. Even when the resulting metal wire is inserted into a plasma generating capillary or nozzle, it is possible to perform these processes without melting or breaking the metal wire.

The present invention relates to a microplasma processing method and apparatus for generating a high-frequency microplasma in a nozzle or a thin tube having a diameter of several millimeters or less, and a high-frequency voltage applied to generate plasma is modulated periodically or irregularly. And generating plasma intermittently.
FIG. 2 shows the basic concept of the high-frequency modulation control of the present invention. The upper part (a) shows the so-called pulse plasma generation in which power is turned on and off to modulate the high-frequency for plasma generation. As shown in the lower part (b), generation and disappearance of plasma or generation of high output and low output of plasma can be repeated.

  In the present invention, the voltage waveform applied for modulation is not limited to the rectangular wave as shown in FIG. 2, but may be a triangular waveform or a sine waveform as shown in FIG. Moreover, it is not restricted to the thing of a fixed period like FIG. 2, FIG. 3, Even if it is an indefinite period like FIG. 4, there is no problem. What is important is to provide a time for the applied voltage to be turned off periodically or irregularly or to have a low output, and the voltage waveform may have any shape. For example, as shown in FIG. 5, it is possible to intermittently generate plasma by periodically turning off a high-frequency output that increases with time. In this case as well, it goes without saying that the same effect can be obtained even if the OFF time is provided indefinitely.

It is possible to reduce the total energy of the plasma by incorporating such a disappearance of the plasma or a low power generation state periodically or irregularly. This leads to a reduction in thermal damage to the plasma and the materials present around it. Even if the plasma generated by argon gas or argon / hydrogen mixed gas has higher enthalpy than the plasma generated by helium gas, the plasma temperature (gas temperature) is so low that it can be touched by hand. It is possible to keep on.
Therefore, plasma can be generated in a nozzle with a thin tube wall that is inferior in heat resistance, for example, in a nozzle having an inner diameter of several μm or less produced by heating and pulling a thin tube of glass or quartz.

According to the method and apparatus of the present invention, so-called patterning such as dot or line drawing by vapor deposition, which has been attempted with conventional microplasma, is also possible.
In the method and apparatus of the present invention, the material used as the substrate to be processed installed downstream of the outlet of the narrow tube or nozzle is not limited to a heat-resistant material such as metal, metal oxide, glass, ceramics, for example, paper. Even a material having no heat resistance such as can be subjected to vapor deposition without causing thermal damage.

When the method and apparatus of the present invention is applied to a material deposition technique using a metal wire inserted into a narrow tube or nozzle as a raw material, a low melting point material or a noble metal wire can be used as the raw material. It becomes.
That is, due to a decrease in the total energy of the plasma, here the heat capacity, the low melting point material and the noble metal wire are gradually melted away by etching or the like without being instantaneously melted after the generation of the modulated plasma, and installed downstream of the nozzle or the outlet of the narrow tube. It is efficiently deposited on the substrate.

In addition, the high-speed state transition from the high-output state to the low-output state or from the low-output state to the high-output state induced by the high-frequency modulation of the present invention results in the generation of active chemical species different from the continuous generation. Therefore, a reaction field different from that in the case of continuous generation can be realized, and it can be expected to bring about a new effect in material deposition.
Further, the plasma swaying caused by the high frequency modulation of the present invention also enables the generation and maintenance of plasma by applying high frequency at a low output. This is because the fluctuation of the electric field caused by the modulation of the applied high frequency promotes the movement of charged particles in the gas, and the collision between charged particles required for plasma generation and maintenance is sufficiently promoted even at low power. Because.
Actually, plasma generation at 1 W or less is also possible, and this low power generation is also one of the factors that make it possible to apply the temperature drop of the plasma, that is, the material deposition to the low melting point material. is there.

  In the present invention, not only the purpose of lowering the plasma gas temperature as described above, but also increasing the high-frequency output, it is possible to obtain a plasma having a gas temperature that is optimal for the synthesis of inorganic materials and the like. Needless to say. In this case, the effect brought about by the non-equilibrium caused by the modulation of the plasma can be expected to give a peculiar result different from the continuously generated plasma.

Hereinafter, the present invention will be described with reference to specific examples, but the present invention is not limited to these examples.
(Example of material deposition on low melting point film using low melting point metal wire)
An example in which a low melting point metal wire is used as a raw material and a low melting point metal or a metal compound is deposited on a low melting point film is shown.
FIG. 6 is a diagram showing an outline of the apparatus used in the present embodiment, in which 1 is a plasma generating thin tube, 2 is a low melting point metal wire, 3 is an arbitrary waveform generation system, 4 is a function generator, A high frequency generator, 6 is a high frequency matching device, 7 is a high frequency application electrode, 8 is a gas supply pipe, and 9 is a material to be processed. In the apparatus shown in FIG. 6, a coil-shaped electrode is used as the high-frequency application electrode 7. However, in the present invention, the shape of the high-frequency application electrode is not limited to the coil shape. It may be a tube or a metal plate.
In this example, tin having a melting point of about 230 ° C. was used as the low melting point metal and deposited on a polyethylene terephthalate (PET) film having a melting point of about 250 ° C.

  A tin wire 2 having a diameter of 100 μm is inserted into the plasma generating capillary 1, preferably a plasma generating capillary 1 having an inner diameter of 1 mm or less. 500 ccm is supplied from the supply pipe 8. A voltage waveform signal having a waveform as shown in FIG. 3 is generated by the arbitrary waveform generation system 3 and transmitted from the function generator 4 to the high-frequency power source 5. The high-frequency matching unit 6 outputs the high-frequency 450 MHz of the output waveform corresponding to the waveform. To the electrode 7 installed around the plasma generating thin tube. By applying a high frequency of 1 W output, plasma is intermittently generated in the narrow tube and is ejected from the narrow tube outlet. At this time, plasma is naturally generated without requiring ignition by a trigger or the like.

  The setting of the above device is only an example, and even if it is changed from the above, such as high frequency, function generator frequency, signal shape, electrode shape, etc., the high frequency is modulated and plasma is intermittently generated in the nozzle. If it is generated, it is obvious that the same effect as described below can be obtained, and it is not included in the present invention.

FIG. 7 is an optical micrograph of the deposit formed on the PET film placed 2 mm downstream from the outlet of the capillary tube as described above. It can be seen that the material is deposited in a circular shape centering on the plasma irradiation region, and no damage is observed due to the heat flow rate from the plasma.
FIG. 8 shows the analysis result of the deposited thin film by XPS, which shows that the tin component was ejected from the nozzle and deposited. In this process, the deposited tin component was oxidized because the thin film deposition step was performed in the atmosphere without sealing the periphery of the deposition region with an inert gas or the like. That is, when this process was performed in the atmosphere, it was shown that synthesis and vapor deposition of low melting point metal oxides were performed in one step.
FIG. 9 is a scanning electron microscopic photograph of the surface of the deposited thin film. Particles generated by evaporation or etching by intermittently generated low-temperature plasma collide and deposit on the PET film, and are dense. It can be seen that a thin film has been produced. The thin film formed according to the present invention is a thin film having a strong adhesive force that does not peel even when an external force such as bending a PET film is applied.

In this way, by making the plasma generation in the nozzle installed in the atmosphere an intermittent generation method, it becomes possible to use a low-melting-point metal wire typified by tin as a raw material. And the compound can be densely deposited on the substrate placed downstream of the nozzle.
Since the plasma generated intermittently has a low gas temperature and does not cause thermal damage to the substrate installed downstream of the nozzle, the material can be directly deposited on a low melting point material such as PET. Needless to say, the material can be deposited on the high melting point substrate.

Here, although the example of deposition of tin oxide and the example of deposition on PET were shown, this invention is not limited to these. A thin film can be produced by using any kind of low melting point material wire such as magnesium as a raw material. The material for depositing the thin film can be deposited not only on PET but also on all low melting point materials such as paper and all high melting point materials such as alumina and silicon.
Moreover, although the said example was related with the oxide, if the amount of hydrogen mixed in the argon gas is set to an appropriate amount, pure metal can be deposited by the reduction effect of the hydrogen gas.
Further, by introducing various reactive gases such as nitrogen into the plasma, a thin film of a metal compound such as nitride can be produced in the same manner as described above.

Although the thin film deposition has been described in the above embodiment, this method can also disperse nanoparticles in a certain region, not as a thin film, by shortening the process. Such a dispersion technique may have an effect of improving the adhesion of a different kind of substance to a local region of the substrate, for example, and an example of an industrial application is to improve the bonding property at the time of material bonding. The effect of can be considered.
Further, during the vapor deposition process, the nozzle or the substrate is scanned in a certain range, so that the material can be deposited over a wide area on the substrate.

(Example of material deposition on the paper surface using precious metal wires)
In this example, a noble metal was deposited on the paper surface in the atmosphere using the apparatus shown in FIG. 6 in the same manner as in the previous example except that a gold wire was used as the noble metal wire.
As in the previous example, the paper was not damaged even when the plasma was in direct contact with the paper surface installed downstream of the nozzle.

FIG. 10 is an optical micrograph of the deposit formed on the paper surface 2 mm downstream from the outlet of the thin tube. It can be seen that gold is deposited in a circular shape around the plasma irradiation region. Although the plasma was generated at a close distance of only 2 mm from the nozzle outlet, and the ejected plasma jet was brought into direct contact with the paper, no traces of paper burn were observed. This is an empirical example showing that the temperature of the plasma generated intermittently is low, for example, at room temperature.
FIG. 11 shows the result of XPS analysis of a thin film obtained under exactly the same conditions as in FIG. This result clearly shows that the deposited material is pure gold that does not contain any impurities such as oxygen and plasma generating thin tube material.

In this way, gold (melting wire in the embodiment) having a melting point of 1064 ° C. and a boiling point of 2856 ° C. is affected by the plasma in the narrow tube, and fine particles are generated and transported and deposited downstream. As described above, since the developed plasma generated intermittently has a gas temperature at room temperature, the process of generating fine particles from the wire is not controlled by melting or evaporation.
In the process of the present invention, at the moment when plasma is generated, the impact caused by the explosive increase in the pressure in the narrow tube contributes to the generation of fine particles, and in the plasma accelerated at high speed by the intermittently repeated impact. The charged particles collide with the gold wire, and as a result, the wire surface is etched or sputtered to generate fine particles.

  As described above, according to the present invention, it is possible to easily perform etching of a noble metal solid in a thin tube installed in the atmosphere. The reason why noble metal has oxidation resistance can be considered as a reason why pure noble metal that is not oxidized at all can be deposited even though the above process is performed in the atmosphere. In addition, the deposition process of the developed technology is dominated by physical factors such as etching, and it seems that one of the factors is that it is a process that does not involve the gas phase reaction of the active species generated by evaporation by heat. .

  FIG. 12 is a scanning electron micrograph of the gold fine particles deposited in the above example. Gold fine particles having a diameter of about 20 nm are deposited. The photograph shown here is an example in which fine particles are deposited with a distance of several nanometers to several tens of nanometers from each adjacent microparticle.

  The deposition mode of such fine particles can be controlled by changing the process time. Needless to say, if the process time is lengthened, it is possible to produce a continuous film as shown in FIG. 9 in the tin oxide deposition example, and by shortening the process time, FIG. It is also possible to deposit the particles in a more sparse state than the examples, ie in a more distributed manner. Such deposition as particles are dispersed, for example, may have an effect of improving the adhesion of different substances to the substrate. For example, in terms of industrial application, material bonding In this case, an effect such as improvement in bonding property can be considered.

Next, a method for generating plasma in a very fine nozzle having an inner diameter of several μm will be described.
The fine tube nozzle used in the present invention is produced by heat-stretching an insulating straight tube such as glass having an inner diameter of several mm or less, preferably a quartz tube. In order to stably generate plasma in such a fine nozzle, the following several electrode arrangement methods are possible.
FIG. 13 shows a method of combining a ring-shaped electrode and a wire. In the figure, 2 represents a metal wire, 8 represents a gas supply pipe, 10 represents a very fine nozzle, and 11 represents a ring-shaped high-frequency applying electrode. .

As shown in FIGS. 13A and 13B, one of the two ring-shaped electrodes 11 is set as a high-frequency power source, and the other is installed. Desirably, the ring-shaped electrode on the jet outlet side (upstream) is desirably connected to the high-frequency generator, and the other (downstream) ring-shaped electrode is grounded, but the reverse is also possible. Although it is desirable to insert the metal wire 2 inside the nozzle 10, plasma may be generated and maintained without it. In the case of this electrode installation method, the metal wire inserted therein may not be grounded via the upstream metal gas pipe.
With regard to the insertion depth of the wire, it may be inserted further downstream than the downstream electrode as shown in (a), or may be inserted between both electrodes as shown in (b).
In addition, as shown in FIG. 3C, a method in which one ring electrode 11 and the insertion metal wire 2 are combined is also effective. In this case, it is desirable that the ring-shaped electrode 11 is connected to the high frequency generator and the insertion wire 2 is grounded via the metal gas feed pipe 8.
Further, even if the ring-shaped electrode 11 is replaced with a coil as shown in FIG. 6 or a sandwiching electrode such as a tube or a mouth clip, the same effect can be obtained.

  Using the above device set, a modulated signal as shown in FIGS. 2 to 5 is transmitted to a high frequency to generate a modulated plasma. As described above, since the modulated plasma has a low total heat amount, the tube wall is not damaged even in the nozzle tip having a thin tube wall thickness. In addition, the effect of causing a plasma to be ejected from the tip of the nozzle having an inner diameter of several μm is brought about by the rapid pressure increase inside the nozzle corresponding to the swaying caused by the modulation.

  The plasma using this ultrafine nozzle can be applied in general material processes. That is, application to material deposition is possible, and the size of the region to be processed can be reduced to several microns or even nano order.

  The method and apparatus of the present invention not only enables material deposition, but also enables the production of polymer thin films. In addition, the present invention may have an effect of improving the adhesion of different substances to the substrate. As an example of industrial application, the use of the present invention for the purpose of improving the bondability during material bonding Can be considered.

The conceptual diagram of the continuous generation mode of high frequency microplasma. The conceptual diagram of a high frequency pulse modulation microplasma generation mode. The figure which shows the example of the output waveform of the applied voltage which can carry out modulation generation of the high frequency microplasma. The figure which shows the example of the irregularly applied voltage waveform which can carry out the modulation | alteration generation | occurrence | production of a high frequency microplasma. The figure which shows the example of the applied voltage waveform of the saw-shaped form which can carry out modulation generation of the high frequency microplasma. Schematic diagram of a modulated microplasma generator. An optical micrograph of tin oxide deposited on a PET film. The figure which shows the XPS analysis result of the tin oxide deposited on the PET film Scanning electron micrograph of tin oxide deposited on a PET film. An optical micrograph of gold deposited on paper. The figure which shows the XPS analysis result of the gold | metal | money deposited with the modulation | alteration microplasma. Scanning electron micrograph of gold microparticles deposited by modulated microplasma The figure which shows the outline | summary of the microplasma generation method in a fine nozzle.

Explanation of symbols

1: Thin tube for plasma generation 2: Metal wire 3: Arbitrary waveform generation system 4: Function generator 5: High frequency generator 6: High frequency matching device 7: High frequency application electrode 8: Gas supply tube 9: Material to be processed 10: Ultrafine nozzle 11: Ring-shaped high-frequency application electrode

Claims (8)

A microplasma processing method for generating a high-frequency plasma in a plasma generating capillary or a plasma generating nozzle by applying a high-frequency voltage, irradiating the generated plasma toward a substrate to be processed, and depositing a thin film on the substrate Because
As a raw material, using a low melting point wire or a noble metal wire arranged in the narrow tube or nozzle,
A microplasma processing method, wherein plasma is generated intermittently by modulating the high-frequency voltage.   The microplasma processing method according to claim 1, wherein a voltage waveform applied for the modulation is any one of a rectangular waveform, a triangular waveform, and a sine waveform.   The microplasma processing method according to claim 1, wherein the voltage waveform applied for the modulation has a constant period or an indefinite period. The microplasma processing method according to claim 1, wherein an inert gas is introduced into the narrow tube or the nozzle. Plasma generating narrow tube or plasma generating nozzle, high frequency applying electrode for generating plasma in the thin tube or nozzle, plasma generating high frequency power source for supplying a high frequency voltage to the electrode, substrate to be processed, and generated A microplasma processing apparatus for depositing a thin film on a substrate, comprising at least means for irradiating plasma toward a substrate to be processed,
While placing the low melting point wire or noble metal wire as a raw material in the narrow tube or nozzle,
A microplasma processing apparatus comprising means for intermittently generating plasma by modulating the high-frequency voltage. 6. The microplasma processing apparatus according to claim 5, further comprising means for applying a voltage having a rectangular, triangular, or sine waveform for the modulation. 6. The microplasma processing apparatus according to claim 5, further comprising means for applying a voltage having a waveform having a constant period or an indefinite period for the modulation. The microplasma processing apparatus according to any one of claims 5 to 7, further comprising means for introducing an inert gas into the narrow tube or the nozzle.