JP7328500B2 - Atmospheric plasma processing equipment - Google Patents

Description

The present disclosure relates to an atmospheric pressure plasma processing apparatus that irradiates a target with active particles (plasma) generated by near-atmospheric discharge.

Conventionally, various techniques for generating plasma under atmospheric pressure are known. For example, in Patent Document 1, a high-voltage electrode and a ground electrode are provided, and a large number of openings are formed in the ground electrode. A device is disclosed through which a target can be irradiated.

Japanese Patent Publication No. 2004-535041

However, in the method of irradiating the target with the plasma that has passed through the ground electrode as in Patent Document 1, the effective irradiation distance tends to be short. As a result, the shape of the target tends to be restricted, and it is also disadvantageous in terms of workability.

The present disclosure has been made in view of the problems of the prior art, and one of the technical problems to be solved is to provide an atmospheric pressure plasma processing apparatus that suitably irradiates a target with plasma generated by near-atmospheric pressure discharge. one.

An atmospheric pressure plasma processing apparatus according to a first aspect of the present disclosure includes an electrode plate to which a voltage is applied as a high voltage electrode, a dielectric disposed on the ground electrode side surface of the electrode plate, and an irradiation window having a plurality of openings spaced apart from each other, and a gas to be used for discharge is supplied between at least the dielectric and the irradiation window. and a plurality of conductive small pieces attached to regions of the surface of the dielectric on the ground electrode side facing the openings, and the irradiation window. When a ground electrode is arranged downstream of the gas, a discharge is generated in the opening by applying a voltage to the electrode plate, and a plurality of discharge gases containing active particles generated by the discharge are generated. from the opening toward the ground electrode.
An atmospheric pressure plasma processing apparatus according to a second aspect of the present disclosure includes an electrode plate to which a voltage is applied as a high voltage electrode, a dielectric disposed on the ground electrode side surface of the electrode plate, and an irradiation window having a plurality of openings spaced apart from each other, and a gas to be used for discharge is supplied between at least the dielectric and the irradiation window. and a gas supply path for performing the irradiation, wherein the irradiation window includes a plate-like member made of an insulator in which a plurality of the openings are formed, and the irradiation window includes a conductive material on the inner surface of the opening, respectively. is attached, and a ground electrode is arranged on the downstream side of the gas with respect to the irradiation window, a discharge is generated in the opening by applying a voltage to the electrode plate, and the discharge generated by the discharge A discharge gas containing active particles is ejected from the plurality of openings toward the ground electrode.
An atmospheric pressure plasma processing apparatus according to a third aspect of the present disclosure includes an electrode plate to which a voltage is applied as a high voltage electrode, a dielectric disposed on the ground electrode side surface of the electrode plate, and An irradiation window arranged at intervals on the ground electrode side and having a plurality of openings spaced apart from each other; an intermediate electrode provided in the irradiation window; a gas supply path for supplying between a dielectric and the irradiation window, wherein a first voltage is applied when a ground electrode is arranged downstream of the gas with respect to the irradiation window. A discharge is generated in the opening by applying a second voltage between the electrode plate and the intermediate electrode and applying a second voltage between the intermediate electrode and the ground electrode, and the activation caused by the discharge is generated. A discharge gas containing particles is ejected from the plurality of openings toward the ground electrode.

An atmospheric pressure plasma processing apparatus according to a fourth aspect of the present disclosure includes an electrode plate to which a voltage is applied as a high voltage electrode, a dielectric disposed on the ground electrode side surface of the electrode plate, and an irradiation window having at least one slit-like opening formed thereon and spaced apart on the side of the ground electrode; and a gas to be used for discharge is supplied between at least the dielectric and the irradiation window. and a conductive small piece affixed to a region of the surface of the dielectric on the ground electrode side facing the opening, wherein the irradiation window is provided with a gas supply path for In the case where a ground electrode is arranged downstream of the gas, a discharge is generated in the opening by applying a voltage to the electrode plate, and the discharge gas containing active particles generated by the discharge is discharged from the opening. It is jetted in a slit shape toward the ground electrode.
An atmospheric pressure plasma processing apparatus according to a fifth aspect of the present disclosure includes an electrode plate to which a voltage is applied as a high voltage electrode, a dielectric disposed on the ground electrode side surface of the electrode plate, and an irradiation window having at least one slit-like opening formed thereon and spaced apart on the side of the ground electrode; and a gas to be used for discharge is supplied between at least the dielectric and the irradiation window. and a gas supply path for the irradiation, wherein the irradiation window includes a plate-shaped member made of an insulating material in which a plurality of the openings are formed, and a conductive material is attached to the inner surface of the opening in the irradiation window. In the case where a ground electrode is arranged downstream of the gas with respect to the irradiation window, a discharge is generated in the opening by applying a voltage to the electrode plate, and the active particles generated by the discharge discharge gas is jetted from the opening toward the ground electrode in a slit shape.
An atmospheric pressure plasma processing apparatus according to a sixth aspect of the present disclosure includes an electrode plate to which a voltage is applied as a high voltage electrode, a dielectric disposed on the ground electrode side surface of the electrode plate, and An irradiation window having at least one slit-like opening formed thereon, an intermediate electrode disposed on the irradiation window, and a gas to be used for discharge are arranged at a distance on the ground electrode side, and comprise at least the above-mentioned a gas supply path for supplying between a dielectric and the irradiation window, wherein a first voltage is applied when a ground electrode is arranged downstream of the gas with respect to the irradiation window. A discharge is generated in the opening by applying a second voltage between the electrode plate and the intermediate electrode and applying a second voltage between the intermediate electrode and the ground electrode, and the activation caused by the discharge is generated. A discharge gas containing particles is jetted from the opening toward the ground electrode in a slit shape.

According to the present disclosure, large-capacity plasma can be efficiently generated.

1 is a diagram showing an external configuration of a plasma processing apparatus according to a first embodiment; FIG. 4 is a partial cross-sectional view of the device main body; FIG. It is a front view of an irradiation window. It is a figure for demonstrating 2nd Example. FIG. 11 is a diagram for explaining an electrical configuration in the third embodiment; FIG.

Hereinafter, plasma processing apparatuses according to several embodiments will be described with reference to the drawings. Part or all of the configuration in each embodiment can be applied to each other.

"First Example"
The plasma processing apparatus 1 in the first embodiment ionizes a predetermined gas under atmospheric pressure to generate plasma. In the following description, the plasma processing apparatus 1 mainly performs plasma processing using water as a target. In recent years, plasma-treated water is expected to be applied as plasma activated medium (PAM) in the medical field, agriculture field, and the like. However, the plasma processing apparatus 1 can also target various substances other than water.

<Configuration>
First, referring to FIG. 1, a schematic configuration of a plasma processing apparatus 1 is shown. The plasma processing apparatus 1 has at least an apparatus main body 2 . Additionally, the plasma processing apparatus 1 may have at least one of the ground electrode 3, the hose 5, the wiring 9a, and the power supply unit 9 (constant voltage power supply). A hose 5 and a wiring 9a are connected to the device body 2 . The hose 5 is connected to a gas supply source such as a gas cylinder. Also, the wiring 9 a is connected to the power supply unit 9 . The power supply unit 9 outputs a pulse current with a frequency on the order of kHz to the device body 2 . In the device body 2, plasma is generated based on this pulse wave. The frequency of the output from the power supply unit 9 may be, for example, several kHz to several tens of kHz. Moreover, it is not necessarily limited to the kHz order, and may be, for example, the MHz order or the GHz order.
The device main body 2 may be used, for example, as a hand-held plasma processing device. In this case, for example, the device main body 2 may be formed with a grip portion for the user to grip.

Further, in FIG. 1, a ground electrode 3 is arranged below the plasma processing apparatus 1 separately from the apparatus main body 2 . The ground electrode 3 is electrically grounded. A SUS plate is used as the ground electrode 3 in the first embodiment. A target T for plasma processing is arranged between the ground electrode 3 and the apparatus main body 2 . If the target T is a conductor, the target T can also serve as a ground electrode.

The plasma processing apparatus 1 of the first embodiment has at least an electrode plate 11 , a dielectric 13 , an irradiation window 15 and a gas inlet 20 . Moreover, the plasma processing apparatus 1 further has a case 19 . Case 19 accommodates electrode plate 11 , dielectric 13 , and irradiation window 15 . In the first embodiment, the case 19 is formed in a cylindrical shape with a diameter of about 100 mm, and its lower surface is open to the atmosphere.

The electrode plate 11 is electrically connected to the wiring 9a, so that a voltage is applied as a high-voltage electrode. The electrode plate 11 has a flat portion and is arranged with the flat portion facing the ground electrode 3 . In the first embodiment, copper is used as the material of the electrode plate 11 as an example. More specifically, the electrode plate 11 is formed as a copper plate with a diameter of approximately 70 mm. However, the material of the electrode plate 11 is not necessarily limited to this, and various conductors can be used as the material of the electrode plate 11 .

The dielectric 13 is arranged on the ground electrode side surface of the electrode plate 11 . It is preferable that the dielectric 13 and the electrode plate 11 are arranged without leaving a gap. The entire ground electrode side surface of the electrode plate 11 may be covered with the dielectric 13 . The dielectric 13 may be integrally joined with the electrode plate 11 . Dielectric 13 prevents arcing between electrode plate 11 and ground electrode 3 . Furthermore, it is also possible to promote the uniform emission of electrons from the entire electrode. Dielectric 13 is preferably a ferroelectric. In the first embodiment, lithium niobate is used as the material of the dielectric 13 as an example. However, it is not necessarily limited to this, and other ferroelectrics such as piezo may be used. In addition, a general dielectric such as quartz may be employed as the material of the dielectric 13 without being limited to a ferroelectric.

The irradiation window 15 is spaced apart from the dielectric on the ground electrode 3 side. The irradiation window 15 of the first embodiment is a plate-like member that covers the lower side of the case 19 . In the apparatus main body 2, at least the lower surface (ground electrode side surface) of the irradiation window 15 is exposed to the atmosphere. Further, as shown in FIGS. 2 and 3, the irradiation window 15 is formed with a plurality of openings 16 spaced apart from each other. The irradiation window 15 may be an insulating member, such as insulating ceramics. The plurality of openings 16 may be formed at intervals such that the flow rate of the gas ejected from each is substantially uniform. As shown in FIG. 3, the opening 16 has a circular cross section in the first embodiment, but the cross section is not necessarily limited to this, and can be appropriately changed to an irregular shape such as a rectangle.

In the first embodiment, the distance between the irradiation window 15 and the dielectric 13 may be constant at each position. If the gap is too narrow, the flow of gas will be hindered, and if the gap is too wide, plasma generation efficiency will decrease. Therefore, as an example, in the first embodiment, the distance between the irradiation window 15 and the dielectric 13 is set within the range of 0.5 mm or more and 1.5 mm or less. However, it is not necessarily limited to this, and the interval can be changed as appropriate. A spacer 14 may be provided between the irradiation window 15 and the dielectric 13. By providing the irradiation window 15 and the dielectric 13 with the spacer 14 interposed therebetween, the above distance is maintained. may

In the first embodiment, a conductive piece 17 is adhered to a region facing each opening 16 on the lower surface (ground electrode side surface) of the dielectric 13 . When a voltage is applied to the electrode plate 11 , charges are concentrated on the small pieces 17 . This makes it easier for plasma to be generated between the electrode plate 11 and the ground electrode 3, especially at the locations where the small pieces 17 are arranged. The area of the small piece 17 may be equal to the cross-sectional area of the opening 16 (cross-sectional area in the direction intersecting the depth direction). However, the term "equal" here is not limited to the case where the area of the small piece 17 and the cross-sectional area of the opening 16 completely match, and some error may be allowed. In addition, in the first embodiment, both are formed in a circular shape with a diameter of 3 mm. Further, similarly to the cross-sectional shape of the opening 16, the shape of the small piece 17 is not limited to a circular shape, and various shapes can be appropriately adopted.

The gas inlet 20 forms a gas supply path. The gas inlet 20 introduces gas to be used for discharge into the case 19 . The gas introduced into the case 19 is discharged out of the case 19 through the opening 16 of the irradiation window 15 through the flow path indicated by the dotted line in FIG. In the process, gas is supplied at least between the dielectric 13 and the irradiation window 15 in the first embodiment. A so-called inert gas is used as the gas for discharge. As an example, in the first embodiment, helium gas is used. However, the gas is not necessarily limited to this, and a rare gas other than helium may be used. Also, a gas with low reactivity such as nitrogen may be used as the inert gas. Further, the gas inlet 20 may be provided with an unillustrated adjustment valve, and the flow rate of the gas introduced into the case 19 may be adjusted by adjusting the opening degree of the valve in the adjustment valve.

<Description of operation>
Next, the operation of the device according to the above embodiment will be described. First, the position of the apparatus main body 2 with respect to the ground electrode 3 is adjusted within a range in which ionized gas is generated between the irradiation window 15 and the ground electrode 3 and the target is irradiated with the ionized gas. In other words, the position of the device body 2 can be appropriately adjusted according to various conditions such as the type of inert gas, the flow rate, and the applied voltage. When helium gas is used as in the first embodiment, the distance from the dielectric 13 to the ground electrode 3 is adjusted to 18 mm to 35 mm. At this time, the distance between the lower surface of the irradiation window 15 and the ground electrode 3 is approximately 10 mm to 27 mm. Water is arranged as a target T between the ground electrode 3 and the irradiation window 15 . In this case, the water may be contained in a container such as a Petri dish whose upper surface is open.

Next, helium gas is introduced into the case 19 from the gas inlet 20 . The flow rate of helium gas is adjusted in the range of 3 L/min to 20 L/min (more preferably in the range of 5 L/min to 12 L/min). With the helium gas in the case 19 having an appropriate concentration, the power supply unit 9 (constant voltage power supply) is driven to apply a high voltage to the electrode plate 11 . For example, a voltage of 9 kV is applied by pulsed output at a frequency of 20 kHz.

When the application of the high voltage to the electrode plate 11 is started, the helium gas is ionized in the space between the lower surface of the dielectric 13 and the ground electrode 3, thereby generating plasma (that is, plasma discharge).

In the space described above, the helium gas is jetted to the target T from each of the plurality of openings 16 through between the dielectric 13 and the irradiation window 15 . Since the effective distance of particles (electrons, ions, and radicals) activated by ionization is short under atmospheric pressure, the wider the distance between the dielectric 13 and the irradiation window 15, the more likely wasteful ionization occurs. Conceivable. On the other hand, in the first embodiment, since the space between the dielectric 13 and the irradiation window 15 is limited, the discharge gas (that is, plasma) containing activated particles is directed through the opening 16 to the target T. , making it easier to irradiate efficiently. Further, in the plasma processing apparatus 1, since the ground electrode 3 is arranged below the irradiation window 15 (on the downstream side of the discharge gas), the space from the irradiation window 15 to the ground electrode 3 can be used for plasma processing. This makes it easier to increase the effective irradiation distance compared to the method of irradiating the target with the plasma that has passed through the ground electrode, as in Patent Document 1. Thereby, the plasma processing apparatus 1 can perform plasma processing efficiently.

Moreover, in the first embodiment, conductive small pieces 17 are adhered to regions facing the respective openings 16 on the lower surface (surface on the side of the ground electrode) of the dielectric 13. The small piece 17-opening 16-grounding Helium gas present in the space connecting the three electrodes 3 is intensively ionized. As a result, the percentage of active particles in the discharge gas with which the target T is irradiated can be improved. That is, a large volume of plasma is efficiently generated and irradiated.

In the plasma processing apparatus 1, since the discharge gas is jetted to the target T from each of the plurality of openings 16, the irradiation area of the target T with the discharge gas can be widened. Moreover, since the discharge gas is dispersed and emitted from the plurality of openings 16, when the target T is a liquid such as water, the target T is less likely to be blown away by the discharge gas. As a result, the plasma processing apparatus 1 can perform plasma processing more efficiently.

"Second embodiment"
Next, a plasma processing apparatus according to a second embodiment will be described with reference to FIG. The plasma processing apparatus according to the second embodiment further has a rod-shaped member 17a and a conductive material 16a in addition to the plasma processing apparatus according to the first embodiment. The rest of the configuration of the plasma processing apparatus according to the second embodiment may be the same as that of the first embodiment, so description thereof will be omitted unless otherwise specified.

The bar member 17a is a conductive member extending from the small piece 17 into the opening, as shown in FIG. As shown in FIG. 4, the length of the rod-shaped member 17a may be such that it penetrates the opening 16. As shown in FIG. Also, a conductive material 16 a may be attached to the inner surfaces of the plurality of openings 16 . The conductive material 16 a may be formed in a pipe shape along the opening 16 . Each of the members 16a, 17a is effective in promoting the ionization of the helium gas by facilitating the flow of current in the space connecting the small piece 17-opening 16-ground electrode 3, respectively. However, the length of the conductive material 16a does not need to match the entire length of the opening 16, and may extend up to the middle of the opening 16. FIG.

"Third embodiment"
Next, a plasma processing apparatus 100 according to a third embodiment will be described with reference to FIG. In FIG. 5, the same components as in the first and second embodiments are given the same reference numerals as in the first and second embodiments, and detailed descriptions thereof are omitted.

In the plasma processing apparatus 100 according to the third embodiment, an intermediate electrode 21 is provided between the electrode plate 11, which is a high-voltage electrode, and the ground electrode 3. As shown in FIG. A high voltage is applied between the electrode plate 11 and the intermediate electrode 21 and between the intermediate electrode 21 and the ground electrode 3 . This better prevents arcing between the electrode plate 11 and the ground electrode 3 when plasma is generated under atmospheric pressure.

As shown in FIG. 5, the intermediate electrode 21 is arranged between the ground electrode 3 and the dielectric 13 in this embodiment. At this time, it is preferably arranged near the plurality of openings 16 . In the example of FIG. 5, intermediate electrodes 21 are attached to the inner surface of each opening 16 . Moreover, each intermediate electrode 21 is formed as a separate body. The intermediate electrode 21 also serves as the conductive material in the second embodiment.

In the third embodiment, instead of the power supply unit 9 shown in FIG. 1, a first power supply unit 22 and a second power supply unit 23 are provided. The first power supply unit 22 applies a first voltage between the electrode plate 11 and the intermediate electrode 21 . As an example, the first voltage may be approximately 9 kV and 20 kHz. The second power supply unit 23 also applies a second voltage between each intermediate electrode 21 and the ground electrode 3 . As an example, the second voltage may be approximately 4.5 kV and 60 Hz.

In the third embodiment, a first voltage is applied between the electrode plate 11 and the intermediate electrode 21 arranged with the dielectric 13 interposed therebetween, so that the space between the dielectric 13 and the irradiation window 15 is WHEREIN: Plasma can be efficiently generated. Further, by applying the second voltage between the intermediate electrode 21 and the ground electrode 3, the plasma irradiation distance can be extended. At this time, by appropriately setting the value of the second voltage, the irradiation distance can be extended within a range in which arc discharge does not occur.

Also, in the third embodiment, a resistor (resistor) 24 is provided on each wiring. This resistor 24 can prevent an excessive current from occurring even if an arc discharge occurs.

As described above, in the third embodiment, the occurrence of arc discharge is suppressed more satisfactorily, so it becomes easier to use a gas such as argon gas, which has a relatively high discharge starting voltage, to generate plasma. Of course, it is significant to use the helium gas and others shown in the first embodiment.

<transformation example>
Although the present disclosure has been described above based on the embodiments, the present disclosure is not necessarily limited to the above embodiments, and various modifications are possible.

For example, the plasma processing apparatus 1 according to the above embodiment has the irradiation window 15 in which a plurality of spot-shaped openings 16 are formed. Alternatively, the plasma processing apparatus 1 may have an irradiation window in which at least one slit-like opening is formed. A plurality of slit-shaped openings may be formed, and in this case, a plurality of rows of slits may be formed as openings. In this case, conductive strips formed in the dielectric may be formed directly above each opening. The conductive strip may also be formed in an elongated shape to match the diameter of the opening. Also, a plurality of small pieces may be arranged along the direction of the slit for one opening. In the case of having such a slit-shaped opening, the discharge gas is jetted in a slit-like manner from the opening formed in the irradiation window toward the ground electrode. In this case, similarly to the above embodiment, the plasma treatment can be efficiently performed while the injection pressure is appropriately distributed. Of course, both spot-shaped openings and slit-shaped openings may be formed in one irradiation window.

1 plasma processing apparatus 2 apparatus main body 3 ground electrode 11 electrode plate 13 dielectric 16 opening 15 irradiation window 20 gas inlet

Claims (6)

an electrode plate to which a voltage is applied as a high-voltage electrode;
a dielectric disposed on the ground electrode side surface of the electrode plate;
an irradiation window arranged with a space on the ground electrode side with respect to the dielectric, and having a plurality of openings spaced apart from each other;
a gas supply path for supplying a gas to be used for discharge at least between the dielectric and the irradiation window;
a plurality of conductive small pieces affixed to areas facing the respective openings on the surface of the dielectric on the ground electrode side,
When a ground electrode is arranged downstream of the gas with respect to the irradiation window, a discharge is generated in the opening by applying a voltage to the electrode plate, and the discharge gas contains active particles generated by the discharge. from the plurality of openings toward the ground electrode. an electrode plate to which a voltage is applied as a high-voltage electrode;
a dielectric disposed on the ground electrode side surface of the electrode plate;
an irradiation window arranged with a space on the ground electrode side with respect to the dielectric, and having a plurality of openings spaced apart from each other;
a gas supply path for supplying a gas to be used for discharge at least between the dielectric and the irradiation window;
The irradiation window includes a plate-shaped member made of an insulator in which a plurality of the openings are formed, and a conductive material is attached to the inner surface of each of the openings in the irradiation window,
When a ground electrode is arranged downstream of the gas with respect to the irradiation window, a discharge is generated in the opening by applying a voltage to the electrode plate, and the discharge gas contains active particles generated by the discharge. from the plurality of openings toward the ground electrode. an electrode plate to which a voltage is applied as a high-voltage electrode;
a dielectric disposed on the ground electrode side surface of the electrode plate;
an irradiation window arranged with a space on the ground electrode side with respect to the dielectric, and having a plurality of openings spaced apart from each other;
an intermediate electrode installed in the irradiation window;
a gas supply path for supplying a gas to be used for discharge at least between the dielectric and the irradiation window;
When a ground electrode is arranged downstream of the gas with respect to the irradiation window, a first voltage is applied between the electrode plate and the intermediate electrode, and a second voltage is applied between the intermediate electrode and the intermediate electrode. Atmospheric pressure plasma treatment in which discharge is generated in the opening by applying between the ground electrode and the discharge gas containing active particles generated by the discharge, and the discharge gas containing the active particles generated by the discharge is ejected from the plurality of openings toward the ground electrode. Device. an electrode plate to which a voltage is applied as a high-voltage electrode;
a dielectric disposed on the ground electrode side surface of the electrode plate;
an irradiation window spaced apart from the dielectric on the ground electrode side and having at least one slit-shaped opening;
a gas supply path for supplying a gas to be used for discharge at least between the dielectric and the irradiation window;
a conductive small piece attached to a region facing each of the openings on the ground electrode side surface of the dielectric;
and
When a ground electrode is arranged downstream of the gas with respect to the irradiation window, a discharge is generated in the opening by applying a voltage to the electrode plate, and the discharge gas contains active particles generated by the discharge. is jetted from the opening toward the ground electrode in a slit shape. an electrode plate to which a voltage is applied as a high-voltage electrode;
a dielectric disposed on the ground electrode side surface of the electrode plate;
an irradiation window spaced apart from the dielectric on the ground electrode side and having at least one slit-shaped opening;
a gas supply path for supplying a gas to be used for discharge at least between the dielectric and the irradiation window;
and
The irradiation window includes a plate-shaped member made of an insulating material in which a plurality of the openings are formed, and the irradiation window has a conductive material attached to the inner surface of the opening,
When a ground electrode is arranged downstream of the gas with respect to the irradiation window, a discharge is generated in the opening by applying a voltage to the electrode plate, and the discharge gas contains active particles generated by the discharge. is jetted from the opening toward the ground electrode in a slit shape. an electrode plate to which a voltage is applied as a high-voltage electrode;
a dielectric disposed on the ground electrode side surface of the electrode plate;
an irradiation window spaced apart from the dielectric on the ground electrode side and having at least one slit-shaped opening;
an intermediate electrode installed in the irradiation window;
a gas supply path for supplying a gas to be used for discharge at least between the dielectric and the irradiation window;
and
When a ground electrode is arranged downstream of the gas with respect to the irradiation window, a first voltage is applied between the electrode plate and the intermediate electrode, and a second voltage is applied between the intermediate electrode and the intermediate electrode. Atmospheric pressure plasma for generating a discharge in the opening by applying between the ground electrode and the discharge gas containing active particles generated by the discharge in a slit-like shape toward the ground electrode. processing equipment.

Images