Patent Application
20090116166
The present invention relates to an apparatus and a method for generating atmospheric-pressure plasma in which high-frequency power is supplied to an antenna arranged on a substrate and a gas is introduced into a discharge tube arranged in the vicinity of the antenna to generate inductively coupled plasma under atmospheric pressure.
Conventionally, vacuum plasma generators and atmospheric-pressure plasma generators were too large to be employed in a system which was incorporated into robots and operated therein. However, in recent years, such a compact apparatus for generating atmospheric-pressure plasma has been suggested which generates inductively coupled plasma under atmospheric pressure to provide it as a plasma jet (for example, see Patent Document 1).
As shown in
Furthermore, as shown in
There is also known a method employed in a plasma processing apparatus in which a gas is introduced into a vacuum process chamber and a high frequency is applied between a pair of opposed electrodes to generate plasma, thereby etching a workpiece placed on one electrode. In the method, the selectivity of the etching is ensured as follows, or more specifically, it is ensured as follows that for an insulating film of oxide film which is predominantly etched with ions, polysilicon which is etched with both radicals and ions is etched selectively. That is, to reduce the ion energy that significantly contributes to the etching of the insulating film, the position at which the minimum amplitude of a standing wave produced in a high-frequency supply path is aligned with the position of the electrodes so that the high-frequency bias applied to the electrodes is reduced (for example, see Patent Document 2).
Note that in Patent Document 2, the frequency used is 13.56 MHz in the RF frequency band, and as the method for aligning the minimum amplitude position of the standing wave with the electrode position, a method is disclosed in which the length of a cable between a high-frequency tuner and the electrode is adjusted. This method raises a problem that the cable may take a length of a few meters to adjust the amplitude of the standing wave.
Furthermore, Patent Document 2 mentioned above also describes the configuration with a phase adjuster inserted in the high-frequency supply path. However, this configuration also raises a problem that the phase adjuster is interposed between the high-frequency power supply and the high-frequency tuner to adjust the amount of phase of the phase adjuster, causing the adjustment to be made with difficulty.
[Patent Document 1] Specification of Japanese Patent No.
[Patent Document 2] Japanese Patent Application Laid-Open No. 2002-373883
In Patent Document 1 mentioned above, disclosed are such a principle and the contents of experiments for generating a low-power plasma jet of a high-concentration plasma with stability. That is, to generate stable low-power plasma in a micro-space under atmospheric-pressure, power is efficiently supplied to the plasma by the inductive coupling scheme. This scheme makes use of a VHF band that allows for capturing part of ions and electrons in a micro-discharge tube as well as a dielectric magnetic field that is produced by a current flowing through the antenna. However, Patent Document 1 has not yet provided a sufficient technique for more efficiently generating plasma at lower power consumption and realizing improved compactness.
For example, Patent Document 1 mentioned above has disclosed the contents of an experiment that was carried out at 50 W or less. However, to realize further applications such as processing or surface reforming, it is necessary to further improve the plasma concentration of the micro-plasma jet generated using the same power.
On the other hand, the technique disclosed in Patent Document 2 mentioned above basically relates to a plasma processing apparatus which employs a parallel flat plates scheme. In addition, the technique uses a frequency of the RF frequency band and aims to reduce the high-frequency bias applied to the electrodes in order to enhance the selectivity of processing, thus never suggesting any means for solving the aforementioned problems. Also the method in which the length of the cable is adjusted to thereby adjust the minimum amplitude position of a standing wave is described. However, the method raises a problem that even when a VHF band high frequency is used, the cable is a few tens of centimeters in length, and thus it is not possible to reduce the size of the apparatus enough to accommodate it in a box, for example, with a side of about 10 cm. Furthermore, even when the phase adjuster is used, it is interposed between the high-frequency power supply and the high-frequency tuner, and thus the adjustment is made with difficulty as described above.
Furthermore, when micro-plasma is generated using the plasma chip 40 disclosed in Patent Document 1 mentioned above, the micro-antenna 42 will increase in temperature. When the plasma is generated for a long duration, the micro-antenna 42 will be lifted from the substrate 41 thereby degrading heat dissipation, possibly causing the patterned portion of the micro-antenna 42 to be burnt. In addition, an increase in the temperature of the micro-antenna 42 will cause an increase in resistance, resulting in loss of balance in the matching circuit. This in turn greatly changes the reflection wave from the micro-antenna 42 to reduce the power to be supplied to the micro-antenna 42, thereby reducing the strength of the plasma.
Furthermore, in the configuration provided with the matching circuit 46, the reactance element such as an inductance element or a capacitance element which constitutes the circuit will generate heat, which in turn will change the circuit constants of the matching circuit 46. It is thus impossible to efficiently generate the plasma P with stability.
Furthermore, a large amount of heat is also generated from the trace that connects between the micro-antenna 42 and the matching circuit 46. This will result in a change in the resistance of the trace, thereby causing a change in the circuit constants of the matching circuit 46. It is thus impossible to efficiently generate the plasma P with stability. Note that to prevent the effects of heat generated from the trace, the heat generated from the trace could be dissipated or the trace itself can be shortened. However, such a configuration that meets these methods has not yet been realized.
In this context, in view of the conventional problems mentioned above, the present invention was developed. It is therefore an object of the invention to provide an apparatus for generating atmospheric-pressure plasma in order to generate inductively coupled plasma using VHF band high-frequency power. The apparatus for generating atmospheric-pressure plasma is intended to efficiently generate plasma and reduce the size of the apparatus. It is another object of the invention is to provide a method for generating atmospheric-pressure plasma.
It is also another object to provide an apparatus for generating atmospheric-pressure plasma which can prevent the circuit constants from being changed due to heat generated from a reactance element that constitutes a circuit such as the matching circuit, the antenna, and the trace. This is intended to efficiently generate plasma with stability and realize a compact structure.
In order to achieve the objects mentioned above, an apparatus for generating atmospheric-pressure plasma of the present invention includes: a substrate; an antenna arranged on the substrate; a discharge tube arranged in the vicinity of the antenna; a high-frequency power supply for supplying VHF band high-frequency power to the antenna; a matching circuit for receiving a high frequency from the high-frequency power supply and adjusting a reflection wave; and a phase circuit connected between the matching circuit and the antenna. In the apparatus, the phase circuit has a circuit constant setting such that a position of a maximum value of a current amplitude of a standing wave is in the vicinity of the micro-antenna or a position of a minimum value of a voltage amplitude of the standing wave is in the vicinity of the micro-antenna.
Furthermore, a method for generating atmospheric-pressure plasma according to the present invention includes the steps of: supplying a VHF band high frequency to an antenna arranged on a substrate and introducing a gas into a discharge tube arranged in the vicinity of the antenna to generate plasma; allowing a matching circuit to adjust a reflection wave entering a high-frequency power supply to around 0; and adjusting a circuit constant of a phase circuit interposed between the matching circuit and the antenna so that a position of a maximum value of a current amplitude of a standing wave is in the vicinity of the antenna or a position of a minimum value of a voltage amplitude of the standing wave is in the vicinity of the antenna.
According to the configuration of the present invention described above, a current flowing through the antenna contributes greatly to the generation of the plasma. Thus, the phase circuit is interposed between the matching circuit and the antenna, so that the phase circuit serves to position the maximum value of the current amplitude of the standing wave in the vicinity of the antenna. This makes it possible to efficiently supply the input power as a current flowing through the antenna, thereby generating plasma efficiently. Furthermore, since at a high frequency, the voltage standing wave and the current standing wave are 180 degrees out of phase, the same effect can be obtained by positioning the minimum value of the voltage amplitude of the standing wave in the vicinity of the antenna.
The phase circuit can be formed of either one of or both a first reactance element disposed between one terminal of the matching circuit and one terminal of the antenna and a current-carrying path connecting therebetween, and either one of or both a second reactance element disposed between the other terminal of the matching circuit and the other terminal of the antenna and a current-carrying path connecting therebetween. That is, either one of or both the reactance elements and the current-carrying path having a predetermined length can be used to adjust the amplitude position of a standing wave. Use of the reactance elements makes it possible to provide a more compact configuration. However, the current-carrying path having a predetermined length can be also designed to provide a compact arrangement, thereby providing the same effects.
The first reactance element and the second reactance element each can be formed of at least one of a fixed inductor, a variable inductor, a fixed capacitor, and a variable capacitor.
Furthermore, the elements of the matching circuit which are connected in series to the first and second reactance elements of the phase circuit, respectively, can be coupled together to form those reactance elements of one reactance element.
Furthermore, provision of the elements constituting the matching circuit and the phase circuit on the substrate makes it possible to reduce the overall size of the apparatus for generating atmospheric-pressure plasma. Additionally, if the Radio Law is met or the safety hazards of the apparatus are cleared, it will be possible to develop such an application as the operator holds it by the hand for use.
Furthermore, the antenna is not limited to one which is patterned on a substrate but may also be configured to have a three-dimensional coil arranged on the substrate.
Furthermore, the apparatus for generating atmospheric-pressure plasma according to the present invention includes: an antenna; a discharge tube arranged in the vicinity of the antenna and having an end into which a gas is supplied; a high-frequency power supply for supplying high-frequency power to the antenna; a matching circuit interposed between the antenna and the high-frequency power supply to adjust a reflection wave from the antenna; and a phase circuit interposed between the antenna and the matching circuit for adjusting the phase in the vicinity of the antenna. In the apparatus, the antenna is disposed on a substrate, and one or more other substrates are stacked on the substrate to form a stacked substrate. Furthermore, a planar reactance element constituting the matching circuit or the phase circuit is arranged on the stacked substrate or is sandwiched between the substrates of the stacked substrate. Furthermore, the apparatus can be configured in the same manner even in the absence of the phase circuit.
According to this configuration, the reactance elements constituting the matching circuit and the phase circuit are formed in a planar shape to be arranged on the stacked substrate or sandwiched between the substrates of the stacked substrate. This allows the heat generated from the reactance elements to be dissipated to outside through the substrates smoothly and effectively. This makes it possible to prevent the circuit constants of the matching circuit and the phase circuit from being changed due to an increase in the temperature of the reactance elements. This in turn allows for efficiently supplying the high-frequency power to the antenna with stability, thereby efficiently producing the plasma with stability. Furthermore, since the planar reactance element is sandwiched between substrates of the stacked substrate, a compact configuration can be realized.
Furthermore, a three-dimensional reactance element, constituting the matching circuit or the matching circuit and the phase circuit, is arranged on the substrate having the antenna disposed thereon. This three-dimensional reactance element is covered with the substrate in contact therewith and included within the stacked substrate. This allows the heat generated from the three-dimensional reactance elements to be effectively dissipated through the substrate having them disposed thereon and the substrate covering them. It is thus possible to efficiently produce plasma with stability in the same manner.
Furthermore, the antenna, the discharge tube, both the matching circuit and the phase circuit or only the matching circuit, the trace connecting therebetween, and a coaxial connector for connecting with a power supply coaxial cable may be included in the stacked substrate. This will allow for providing an apparatus for generating atmospheric-pressure plasma, which has a compact configuration with the outer appearance of its main portion consisting of only the block-shaped stacked substrate. Only a tube for supplying a gas and the coaxial cable for supplying high-frequency power need to be connected to this configuration, thereby making it possible to perform plasma processing. It is thus possible to efficiently facilitate various types of plasma processing with stability in a simplified manner.
Furthermore, the planar antenna is sandwiched between substrates in the stacked substrate, and the planar reactance elements are disposed on the substrates sandwiching the antenna. Sandwiching the antenna between the substrates allows for effectively dissipating the heat generated from the antenna and efficiently supplying high-frequency power to the antenna with stability, thereby making it possible to efficiently produce plasma with stability. Additionally, since the substrates are also shared to dispose the planar reactance elements thereon, it is possible to reduce the area and the quantity of substrates, thereby providing a more compact configuration.
Furthermore, the discharge tube and the antenna wound multiple times around it are sandwiched between substrates of the stacked substrate, and the planar reactance element is disposed on the substrate for sandwiching the discharge tube and the antenna. This makes it possible to provide the same effects even when the antenna wound around the discharge tube is employed.
Furthermore, if the reactance element mentioned above is an inductance element which is made of a conductor arranged in a spiral fashion on the substrate, the inductance element easily generates heat. However, the inductance element can be formed in a planar shape and sandwiched between substrates of the stacked substrate, thereby allowing the heat generated to be dissipated to outside through the substrates smoothly and effectively. This will provide particularly significant effects.
Furthermore, the trace provided on a substrate is sandwiched between substrates of the stacked substrate. This allows for effectively dissipating the heat generated from the trace through the substrates. It is also possible to prevent the circuit constants of the matching circuit and the phase circuit from being changed and thus efficiently produce plasma with stability.
Furthermore, the connections of the traces formed on the substrates of the stacked substrate to be connected to each other are arranged so as to overlap each other and are then connected to each other with the substrates in intimate contact with each other being coupled to each other. This allows for providing electrical circuit connections only by the substrates constituting the stacked substrate being coupled to each other while they are in intimate contact with each other. It is thus possible to realize an inexpensive compact configuration which is simplified in configuration and can be easily assembled.
Furthermore, the substrates can be formed of a material selected from the group consisting of alumina, sapphire, aluminum nitride, silicon nitride, boron nitride, and silicon carbide, thereby providing a high thermal conductivity to the substrates and thus a high heat dissipation capability.
Furthermore, the aforementioned apparatus for generating atmospheric-pressure plasma can be mounted in the movable head of a robot system which can displace in the X, Y, and Z directions. This allows for providing a compact plasma processing apparatus which has an extremely enhanced general versatility.
A description will now be made to the embodiments of the present invention.
To begin with, with reference to
As shown in
As shown in
The matching circuit 7 allows the input of a reflection wave to the high-frequency power supply 8 to be adjusted to around 0, the reflection wave occurring when the high-frequency power is supplied to the antenna 3. More specifically, as shown in
As shown in
Furthermore, to actually configure the circuit, the LOAD element 9 and the TUNE element 10 of the matching circuit 7 are formed of a variable element, whereas the first reactance element (Element A) and the second reactance element (Element B) of the phase circuit 6 are formed of a fixed reactance element. With the LOAD element 9 and the TUNE element 10 of the matching circuit 7 being temporarily set to an adequate setting, the first reactance element (Element A) and the second reactance element (Element B) of the phase circuit 6 are selected so that the anti-node of the current amplitude of the standing wave is positioned in the vicinity of the micro-antenna 3. After that, the LOAD element 9 and the TUNE element 10 of the matching circuit 7 are varied for fine adjustments, thereby preferably facilitating the adjustment.
In the present embodiment, as shown in
In the aforementioned configuration, a gas is introduced into the discharge tube 4 through the other end opening on the side opposite to the side 2a of the substrate 2, and VHF band high-frequency power is supplied between the patterned circuits 13a and 13b on the substrate 2 from the high-frequency power supply 8. Since the phase circuit 6 has made an adjustment such that the maximum value of the current amplitude of the standing wave is positioned in the vicinity of the antenna 3, this allows the input power from the high-frequency power supply 8 to be supplied efficiently as a current flowing through the antenna 3. It is thus possible to generate plasma efficiently. Furthermore, the antenna 3, the phase circuit 6, and the matching circuit 7 are arranged on the substrate 2. This makes it possible to provide a compact apparatus, for example, such a compact apparatus that is reduced in size enough to be accommodated in a box with a side of about 10 cm.
Here, with reference to
As shown in Table 1, the element A capacitor and the element B inductor were set as combinations of 10 pF and 100 nH (Example experiment E), 22 pF and 54 nH (Example experiment F), and 120 pF and 9.9 nH (Example experiment G). Then, on each of the combinations, voltage amplitude measurements were made at various distances from point “a” (reference point) in
Furthermore, in each of Example experiments E, F, and G mentioned above, high-frequency power of 50 W at 100 MHz was supplied and an argon gas of 0.7 slm was introduced into the discharge tube. Under these conditions, measurements were made on the intensity of plasma radiation. As a result, Example experiments E and G showed as high radiation intensities as 55000 and 60000 arb.unit, respectively. However, no ignition was observed in Example experiment F. It is thus shown that the voltage amplitude of the standing wave in the vicinity of the antenna 3 can be adjusted to the minimum value, thereby generating a jet of plasma of a high concentration even using low power.
Note that as shown in
In the examples shown in
Furthermore, in the example configuration of
The apparatus 1 for generating atmospheric-pressure plasma according to the first embodiment can provide a compact configuration because the antenna 3 is provided on the substrate 2. Additionally, the phase circuit 6 is interposed between the matching circuit 7 and the antenna 3, and then is adjusted so that the current amplitude or the voltage amplitude of the standing wave occurring in the vicinity of the antenna 3 takes on the maximum value or the minimum value. When compared with the case of adjusting the cable length, this allows for providing a significantly compact configuration by which the antenna 3 can produce generally the maximum plasma. Accordingly, even when plasma is generated using the same input power, it is possible to produce the plasma nearly at its maximum concentration and radiation intensity, thereby developing applications, for example, for processing and surface reforming. Furthermore, the provision of the matching circuit 7 and the phase circuit 6 on the substrate 2 makes it possible to reduce the size of the apparatus 1 for generating atmospheric-pressure plasma and incorporate it into a robot for operation. Additionally, if the Radio Law is met or the safety hazards of the apparatus are cleared, it will be possible to develop such an application as the operator holds it by the hand for use.
Furthermore, the apparatus 1 for generating atmospheric-pressure plasma is applicable to various analyzers in the chemistry and biochemistry fields. In particular, it is also preferably applicable, for example, to the micro chemical analysis systems (μTAS: Micro Total Analysis System) which include the combinations of high-speed separation techniques of a trace amount of substance by gas chromatography or micro-capillary electrophoresis with laser induced fluorescence detections, electrochemical measurements using micro-electrodes, ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy), or ICP mass spectrograph. Furthermore, the apparatus can be utilized in various fields, for example, for cutting by melting a local portion of a workpiece such as a micro-chip used for micro-devices; processing and surface treatment such as etching, deposition of thin film, cleaning, hydrophilic processing, or repellent processing; or high-temperature processing of hazardous substances.
With reference to
As shown in
As shown in
At the center of the other end of the other half region of the first substrate 22 where the antenna 26 is not located, a substrate-side connector 31 is provided which is connected to the high-frequency power supply (not shown) and to which a cable-side connector 30 at a tip of an coaxial cable 29 for supplying high-frequency power is connected. The connector 31 and the antenna 26 are connected to each other via a trace 32 formed on the first substrate 22. Halfway through the trace 32, the reactance elements are provided which form the matching circuit 7 and the phase circuit 6 as shown in
In the present embodiment, the storage groove 27 was provided on the second substrate 23. However, it is also acceptable to provide the storage groove 27 on the first substrate 22 to store the discharge tube 28 therein.
In the present embodiment, the matching circuit 7 is made up of the LOAD-side variable capacitor 9 and the TUNE-side variable capacitor 10, both of which are a three-dimensional reactance element. Furthermore, the phase circuit 6 is made up of the inductance element 15 arranged between the LOAD-side variable capacitor 9 and the antenna 26 and the fixed capacitor 16 arranged between the TUNE-side variable capacitor 10 and the antenna 26. The fixed capacitor 16 is a three-dimensional reactance element. However, as shown in
As shown in
Note that as indicated in
The apparatus 21 for generating atmospheric-pressure plasma, configured as described above, has the planar antenna 26 sandwiched between the first and second substrates 22 and 23 in the stacked substrate 25. It is thus possible to effectively dissipate heat generated from the antenna 26 and efficiently input the high-frequency power into the antenna 26 with stability, thereby efficiently producing the plasma P with stability.
Furthermore, the planar inductance element 15 made up of a spiral conductor is disposed on the second substrate 23 for sandwiching the antenna 26 and then sandwiched by the third substrate 24. This may cause the inductance element to more easily generate heat when compared with other reactance elements. However, the heat generated from the inductance element 15 can be smoothly dissipated outwardly through the second and third substrates 23 and 24 in an effective manner. It is thus possible to prevent the circuit constants of the matching circuit 7 and the phase circuit 6 from being changed due to an increase in the temperature of the inductance element 15. This in turn makes it possible to stably input the high-frequency power into the antenna 26 with improved efficiency and efficiently produce the plasma with stability. Furthermore, since the planar inductance element 15 is also disposed on the second substrate 23 for sandwiching the antenna 26, it is possible to reduce the area and quantity of the substrates 22 to 24 that constitute the stacked substrate 25, thereby realizing a compact configuration.
Furthermore, the connections 34a and 34b, and 35a and 35b, which are to be connected to each other, respectively, are provided on the first substrate 22 and the second substrate 23 so that they overlap each other. Then, the first and second substrates 22 and 23 are coupled to each other while they are in intimate contact with each other, thereby allowing the connections 34a and 34b, and 35a and 35b to be connected to each other, respectively. This allows for providing electrical circuit connections only by coupling together the substrates 22 through 24 constituting the stacked substrate 25 while they are in intimate contact with each other. It is thus possible to realize an inexpensive compact configuration with a simple structure which can be easily assembled.
Note that in the present embodiment, the third substrate 24 was brought into intimate contact with the inductance element 15. However, without using the third substrate 24, the inductance element 15 may also be provided on the second substrate 23, thereby dissipating heat.
With reference to
In the present embodiment, as shown in
In this manner, the stacked substrate 25 made up of the first to fourth substrates 22, 23, 24, and 36 includes the antenna 26, the discharge tube 28, the matching circuit 7, the phase circuit 6, the trace 32 connecting therebetween, and the connector 31. The apparatus 21 for generating atmospheric-pressure plasma is thus composed of the single block-shaped stacked substrate 25 which has no element or trace exposed to outside.
According to this configuration, the three-dimensional reactance elements 9, 10, and 16 constituting the matching circuit 7 and the phase circuit 6 are arranged on the first substrate 22 having the antenna 26 disposed thereon. These reactance elements are covered with the fourth substrate 36 in contact therewith and included within the stacked substrate 25. The heat generated from these reactance elements can be also effectively dissipated through the first substrate 22 and the fourth substrate 36, thereby efficiently producing plasma with stability.
Furthermore, the heat generated from the antenna 26, the discharge tube 28, the matching circuit 7, the phase circuit 6, the trace 32, and the connector 31 is smoothly dissipated to outside from the outer surface of the stacked substrate 25 through the first to fourth substrates 22, 23, 24, and 36 that constitute the stacked substrate 25. It is thus ensured to prevent the circuit constants from being changed due to an increase in the temperature of not only the reactance elements constituting the matching circuit 7 and the phase circuit 6 and the antenna 26 but also the connector 31 and the trace 32. This allows for efficiently generating plasma with stability.
Furthermore, the antenna 26, the discharge tube 28, the matching circuit 7, and the phase circuit 6, the trace 32 connecting therebetween, and the connector 31 are included within the stacked substrate 25. It is thus possible to provide the apparatus 21 for generating atmospheric-pressure plasma which has a compact configuration with the outer appearance of its main portion consisting only of the block-shaped stacked substrate 25. Only the tube (not shown) for supplying a gas and the coaxial cable 29 for supplying high-frequency power need to be connected to this configuration, thereby making it possible to perform plasma processing. It is thus possible to efficiently facilitate various types of plasma processing with stability in a simplified manner.
With reference to
In the second embodiment described above, such an example was shown in which the wavelike flat-shaped antenna 26 is disposed on the first substrate 22 to be sandwiched between the first substrate 22 and the second substrate 23. In the forth embodiment, as shown in
Both end portions of the antenna 38 are disposed so as to overlap a connection 32a of the trace 32 provided on the first substrate 22 and the connection 35b for the inductance element 15, and are sandwiched by the second substrate 23 in intimate contact therewith, thereby being electrically connected to the trace 32 and the inductance element 15. As shown in
According to the present embodiment, the discharge tube 37 and the antenna 38 wound multiple times around it are sandwiched between the first and second substrates 22 and 23 of the stacked substrate 25. The planar inductance element 15 is disposed on the second substrate 23 for sandwiching the discharge tube 37 and the antenna 38. It is thus possible to provide the same effects as those of the first embodiment described above using the antenna 38 wound around the discharge tube 37.
Note that in the embodiments described above, such examples have been shown in which the three first to third substrates 22 to 24 are stacked to form the stacked substrate 25, and the fourth substrate 36 is stacked on the first substrate 22 to form the stacked substrate 25. However, the number of substrates constituting the stacked substrate 25 can be arbitrarily designed depending on the layout of the antennas 26 and 37, the discharge tubes 28 and 37, and each reactance element that constitutes the matching circuit 7 and the phase circuit 6.
In the descriptions of each of the embodiments above, such an example has been explained which has the matching circuit 7 and the phase circuit 6. However, even in the presence of only the matching circuit 7 without the phase circuit 6, the present invention can be applied to a case where the matching circuit 7 has a flat-shaped reactance element, thereby providing the same effects. Furthermore, in the embodiments described above, such an example has been shown in which only the variable capacitors 9 and 10 are used as reactance elements that constitute the matching circuit 7. However, as a matter of course, such a configuration can also be employed which uses a fixed capacitor or an inductance element. In such a case, particularly, the inductance element easily generates heat and is thus preferably sandwiched between substrates serving as a flat-shaped inductance element to be thereby included in the stacked substrate.
Furthermore, the aforementioned apparatus 21 for generating atmospheric-pressure plasma can be mounted in the movable head of a robot system which can displace in the X, Y, and Z directions. This allows for providing a compact plasma processing apparatus which has an extremely enhanced general versatility.
Furthermore, in each of the embodiments described above, only such an example has been explained which provides high-frequency power at a VHF band (30 to 500 MHZ). However, the invention is not limited thereto. The invention is also applicable to a microwave band (500 MHZ or greater), and the second to fourth embodiments can be applied to an RF band (13 to 30 MHZ).
As described above, according to the present invention, the phase circuit is interposed between the matching circuit and the micro-antenna, and the phase circuit is adjusted so that the current amplitude of a standing wave takes on the maximum value or the voltage amplitude of the standing wave takes on the minimum value in the vicinity of the micro-antenna. This allows for efficiently generating a micro-plasma jet at low-power and enhancing the concentration and radiation intensity of the plasma produced at the same input power nearly to the maximum possible limit. It is thus possible to preferably not only apply the invention to the micro-chemical analysis using micro-capillary electrophoresis but also provide high processing capabilities for developing applications such as various types of processing and surface treatment. Furthermore, the reactance elements of the matching circuit and the phase circuit are formed in a planar shape and are sandwiched between the substrates of the stacked substrate, thereby allowing the heat from the reactance elements to be effectively dissipated to outside. This makes it possible to prevent the circuit constants from being changed due to an increase in the temperature of the reactance elements, and efficiently input the high-frequency power into the antenna with stability, thereby efficiently producing the plasma with stability. It is also possible to realize a compact configuration, and thus preferably use the invention for various types of apparatus for generating atmospheric-pressure plasma, particularly, for a compact apparatus for generating atmospheric-pressure plasma to be incorporated into various types systems.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-129193 | May 2006 | JP | national |
| 2006-260602 | Sep 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/057767 | 4/6/2007 | WO | 00 | 12/15/2008 |
