WO2020021831A1 - Plasma generation device - Google Patents

Abstract

This plasma generation device is provided with: a flow path formation section forming a flow path for causing a gas to flow in a predetermined flow direction, and having an opening for discharging the gas at the downstream end of the flow path in the flow direction; first electrodes having a pair of facing surfaces parallelly disposed so as to face each other across the flow path; second electrodes disposed separately from the first electrodes in the flow direction and having a pair of facing surfaces parallelly disposed so as to face each other across the flow path; and a power supply unit for applying an alternating-current voltage across the first and second electrodes. The facing surface of each first electrode is a flat surface that is parallel to the flow direction and that faces the other first electrode, and the facing surfaces of the first electrodes are separated from the flow path by a dielectric material. The facing surface of each second electrode is a flat surface that is parallel to the flow direction and that faces the other second electrode, and the facing surfaces of the second electrodes are separated from the flow path by a dielectric material. With this configuration, it is possible to expose a wide area to plasma without causing problems such as damage from electric current and contamination by an electrode material.

Description

Plasma generator

{Circle over (1)} The present invention relates to a technique for generating a plasma to act on the surface of an object to be treated and performing the surface treatment, and particularly relates to a plasma generator which can be used in the atmosphere.

技術 A technique for irradiating the surface of a processing object with plasma for the purpose of surface processing or modification of the processing object is known. Above all, those utilizing atmospheric pressure plasma which does not require a vacuum chamber can be suitably applied, for example, to a resist stripping process in a semiconductor substrate manufacturing process. In this case, in order to efficiently process a processing target such as a large-area substrate, a plasma generator having a wide irradiation range is required. For example, those capable of irradiating wide plasma from a slit-shaped discharge port are preferable.

技術 As a technique capable of performing such broad plasma irradiation, there is a technique described in Patent Document 1, for example. The plasma irradiation apparatus in this technique is for irradiating an aqueous solution with plasma to generate active species in the liquid. In this technique, an alternating voltage is applied to electrodes provided at both ends of a slit-shaped gas flow path, so that the gas in the flow path is turned into plasma and blown out from an ejection port.

JP 2016-169164 A

(4) The above-described conventional technique turns on plasma by passing an electric current through a gas flowing through a flow path. Here, when the surface of the processing target includes a conductor such as a semiconductor or a metal pattern, a current may flow through the processing target to damage the processing target. Further, since the electrode is exposed to the plasma generation space, the constituent material of the electrode may contaminate the processing target. For this reason, there is a demand for a plasma generator that does not cause a current to flow through a processing target and does not cause a problem of contamination by an electrode substance.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a plasma generator capable of irradiating a wide range of plasma without causing a problem of damage due to electric current and contamination by an electrode material.

In one aspect of the plasma generator according to the present invention, in order to achieve the above object, a flow path for flowing gas along a predetermined flow direction is formed, and at a downstream end of the flow path in the flow direction. A flow path forming part having an opening for discharging the gas, a first electrode having a pair of parallel opposing surfaces disposed to face each other with the flow path interposed therebetween, and the first electrode is disposed in the flow direction. A second electrode having a pair of parallel opposing surfaces spaced apart from each other with the flow path interposed therebetween and a power supply unit for applying an AC voltage between the first electrode and the second electrode; And each of the opposed surfaces of the first electrode is a plane parallel to the flow direction and opposed to the other first electrode, and a gap between the opposed surface of the first electrode and the flow path is provided. Each of the opposed surfaces of the second electrode, which is separated by a dielectric, Parallel the other of the second electrode facing the plane direction, between the channel and the facing surface of the second electrode are separated by a dielectric.

In the invention configured as described above, an electric field is formed between the first electrode and the second electrode separated in the gas flow direction by applying an AC voltage between the first and second electrodes. Although described in detail later, since each of the first electrode and the second electrode is configured to form a pair with the gas flow path therebetween, the first electrode and the second electrode are disposed between the first electrode and the second electrode in the flow path. A particularly strong electric field is formed at the site where it is located. Due to this electric field, discharge occurs in the gas flowing through the flow path, and the gas is turned into plasma. The plasma generated in this manner is discharged from the opening of the flow path forming portion together with the gas. The discharge at this time is a dielectric barrier discharge because the first electrode and the second electrode are separated from the flow path by the dielectric. For this reason, there is no problem that a current flows through the processing target or that the constituent materials of the first electrode and the second electrode adhere to the processing target.

In the first electrode, their opposing surfaces are parallel to each other, and similarly for the pair of second electrodes, their opposing surfaces are parallel to each other. By extending the opposing surfaces parallel to each other in the direction perpendicular to the gas flow direction, it is possible to expand the range in which a uniform electric field distribution can be obtained in the direction. Therefore, uniform plasma can be generated in a region extending long in the direction. Therefore, the irradiation range of the plasma in the direction can be widened.

As described above, in the present invention, plasma is generated by the dielectric barrier discharge for the gas present in the flow path. Therefore, it is possible to perform plasma irradiation without causing a problem of damage due to electric current and contamination by an electrode material. In addition, the range of plasma spread in a direction perpendicular to the gas flow direction is not limited in principle, and can be controlled by the shapes of the flow path and the electrodes. Therefore, it is possible to irradiate a wide range with plasma.

The above and other objects and novel features of the present invention will become more fully apparent from the following detailed description when read in conjunction with the accompanying drawings. However, the drawings are for explanation only, and do not limit the scope of the present invention.

FIG. 1 is an external perspective view showing a principle configuration of a plasma generator according to the present invention. It is the figure which looked at the plasma generator from another direction. It is the figure which looked at the plasma generator from another direction. It is the figure which looked at the plasma generator from another direction. FIG. 4 is a diagram illustrating an electrical behavior in the plasma generator. FIG. 4 is a diagram illustrating an electrical behavior in the plasma generator. FIG. 4 is a diagram illustrating an electrical behavior in the plasma generator. It is a figure which shows the modification of a plasma generator. It is a figure which shows the modification of a plasma generator. It is a figure which shows the modification of a plasma generator. It is a figure which shows the modification of a plasma generator. It is a figure which shows the modification of a plasma generator. It is a perspective view showing the appearance of the plasma generator of this embodiment. FIG. 2 is a partial exploded view of the plasma generator. It is a top view of a plasma generator. It is sectional drawing of a plasma generator. It is sectional drawing of a plasma generator.

実 施 An embodiment of the plasma generator according to the present invention will be described. This plasma generator can be applied to surface treatment in processing steps of various substrates such as a semiconductor substrate and a glass substrate. Further, for example, the present invention is also applicable to a surface modification treatment such as a hydrophilic treatment, a resist stripping treatment, and the like. In addition, the present invention can be used for, for example, surface modification of a print medium in a printing apparatus. First, the principle configuration and operation of the plasma generator according to the present invention will be described with reference to the drawings.

FIG. 1 is an external perspective view showing the basic configuration of the plasma generator according to the present invention. 2A to 2C are views of the plasma generator viewed from another direction. More specifically, FIG. 2A is a top view of the plasma generator, FIG. 2B is a side view thereof, and FIG. 2C is a cross-sectional view taken along line AA of FIG. 2A. Although the electrode plates 13a and 13b on the line AA appear in FIG. 2C, the sectional view taken along the line BB of FIG. 2A also shows that the electrode plates appearing on the cross section are replaced by the electrode plates 14a and 14b. If the shape is the same.

Here, an XYZ orthogonal coordinate system is set as shown in FIG. 1 in order to unify the directions in each drawing. For example, the XY plane can be considered as a horizontal plane, and the Z axis can be considered as a vertical axis. In the following, the (-Z) direction is assumed to be vertically downward. That is, in the following, when simply referring to “up”, it means the (+ Z) direction. In addition, when simply saying “down”, it means the (−Z) direction. In the following, for convenience of explanation, the main surface of the plasma generator 1 is made coincident with the XY plane, but the posture of the plasma generator 1 in actual use is not limited to this and is arbitrary.

主要 The main parts of the plasma generator 1 are the dielectric plates 11 and 12, the electrode plates 13a, 13b, 14a and 14b, the power supply unit 15, and the gas supply unit 19. The pair of dielectric plates 11 and 12 are opposed to each other in parallel with a predetermined gap G therebetween. More specifically, the dielectric plates 11 and 12 are flat plates formed of a plasma-resistant dielectric material such as quartz or ceramic. These are opposed to each other via spacers 16a and 16b defining a gap G to form a parallel plate structure. The spacer 16a extends in the Y direction at the (−X) side end of the dielectric plates 11 and 12. The spacer 16b extends in the Y direction at the (+ X) side end of the dielectric plates 11 and 12. For the material of the spacers 16a and 16b, for example, quartz, ceramic, or the like can be used.

気 体 With such a configuration, the gas flow path P is formed. That is, the gap space surrounded by the lower surface of the upper dielectric plate 11, the upper surface of the lower dielectric plate 12, and the side surfaces of the spacers 16a and 16b has a flat rectangular cross section in the X direction and extends in the Y direction. Road P. An appropriate gas is supplied from the gas supply unit 19 to the opening at the (−Y) side end of the flow path P. The gas sent into the flow path P flows in the flow path P in the (+ Y) direction, and is discharged outside through the slit-shaped opening 17 at the (+ Y) side end. Therefore, the gas flow direction in this example is the (+ Y) direction. In each of the drawings after FIG. 1, the outline arrows indicate the flow direction of the gas sent from the gas supply unit 19 to the flow path P and discharged to the outside through the flow path P.

As shown in FIGS. 1 and 2A, electrode plates 13a and 14a are provided on the upper surface of the dielectric 11 so as to be separated from each other in the Y direction. Specifically, each of the electrode plates 13a and 14a is a plate-shaped conductor plate extending along the X direction to the outside of both ends of the flow path P, and the electrode plate 14a is (+ Y ) Direction, are provided at predetermined intervals.

2B and 2C, a flat electrode plate 13b is provided on the lower surface of the dielectric plate 12 at the same position as the electrode plate 13a in the XY directions. Further, a flat electrode plate 14b is provided on the lower surface of the dielectric plate 12 at the same position as the electrode plate 14a in the XY directions. Hereinafter, a pair of the electrode plates 13a and 13b is referred to as a “first electrode” and is denoted by reference numeral 13. Similarly, a pair of the electrode plates 14a and 14b is referred to as a "second electrode" and is denoted by reference numeral 14.

Thus, the electrode plates 13a and 13b constituting the first electrode 13 are parallel to each other. The electrode plates 14a and 14b constituting the second electrode 14 are also parallel to each other. Therefore, each of the first electrode 13 and the second electrode 14 is a parallel plate electrode, that is, an electrode having a structure in which a pair of plate-like electrode plates are arranged in parallel. The electrode plates 13a and 14a are parallel to each other, and they are on the same plane. Similarly, the electrode plates 13b, 14b are parallel to each other and are coplanar. The flow path P is formed between the electrode plates 13a, 13b, 14a, 14b having such a positional relationship.

電極 The electrode plates 13a and 13b constituting the first electrode 13 are electrically connected. The electrode plates 14a and 14b constituting the second electrode 14 are electrically connected. Then, the power supply unit 15 is electrically connected between the first electrode 13 and the second electrode 14. The power supply unit 15 outputs an AC voltage having an appropriate waveform such as a sine wave, a rectangular wave, or a pulse wave, and the AC voltage is applied between the first electrode 13 and the second electrode 14. The output voltage waveform of the power supply unit 15 may include a DC component.

In such a configuration, a potential difference does not occur between the pair of electrode plates 13a and 13b in the first electrode 13 provided so as to sandwich the flow path P from the Z direction. The same applies to the pair of electrode plates 14a and 14b in the second electrode 14. On the other hand, a potential difference is generated between the electrode 13 and the electrode 14 due to the applied AC voltage, and an electric field is formed therebetween.

FIGS. 3A to 3C are diagrams showing electrical behavior in the plasma generator. 3A and 3B are diagrams schematically showing an electric field formed by applying a voltage. 3A is a diagram viewed from the X direction, and FIG. 3B is a diagram viewed from the Y direction. The broken lines in FIG. 3A indicate lines of electric force when a voltage is applied to each electrode plate.

(3) As shown in FIG. 3A, an electric field is generated in a space between the first electrode 13 ( electrode plates 13a and 13b) and the second electrode 14 ( electrode plates 14a and 14b) to which a potential difference is given. Since both sides of the flow path P are sandwiched between electrode plates having the same potential, the density of electric lines of force in the flow path P becomes particularly high, and a strong electric field is formed. By the electric field formed in this way, plasma of the gas supplied into the flow path P is generated. For example, when the gas supply unit 19 supplies an inert gas such as a rare gas (eg, argon gas), a nitrogen gas, or air to the flow path P, plasma is generated in the flow path P by these gases.

As shown in FIG. 3B, the flow path P having a cross section elongated in the X direction is sandwiched between the electrode plates 13a and 13b (or the electrode plates 14a and 14b) extending to the outside of the flow path P at both ends of X. . Since the electrode plate 13a and the electrode plate 13b (or the electrode plate 14a and the electrode plate 14b) have the same potential, the electric field E generated in the flow path P is substantially uniform in the X direction. Since the applied voltage is an AC voltage, the magnitude and direction of the electric field E periodically change. Due to such an electric field distribution, the plasma PL generated in the flow path P also has a substantially uniform density in the X direction.

By appropriately setting the dimensional relationship of each part, as shown in FIG. 3C, not only the space between the electrode plates 13a and 13b and the electrode plates 14a and 14b in the flow path P but also the outer sides thereof in the Y direction. Can be generated. In some cases, the plasma PL extends further outside the region sandwiched between the electrode plates. If a portion of the plasma PL extends outside the opening 17 at the (+ Y) side end of the flow path P, the plasma generator 1 functions as a plasma ejection device that ejects plasma from the opening 17. I do. By irradiating the processing object such as the substrate with the plasma ejected from the opening 17 in this manner, it becomes possible to perform the surface treatment on the substrate and the like.

As described above, since the plasma PL generated in the flow path P has high uniformity in the X direction, the plasma ejected from the opening 17 is also elongated in the X direction. Therefore, it is possible to perform substantially uniform plasma irradiation on a band-shaped region extending in the X direction on the surface of the processing target.

According to the experiments of the present inventors, the width of the flow path P in the X direction (reference a shown in FIG. 3B) is 15 mm, the distance between the electrodes in the Y direction (reference b in FIG. 3C) is 10 mm, and the flow direction of the gas. In FIG. 3, the distance from the electrode plate 14a, 14b on the downstream side, that is, the (+ Y) side to the opening 17 (reference numeral c shown in FIG. 3C) is 3.5 mm, and the thickness of the dielectric plates 11, 12 (reference numeral d shown in FIG. ) Is 0.3 mm and the size of the gap G (symbol e shown in FIG. 3C) is 1.5 mm, it was confirmed that a wide plasma extending in the X direction was emitted from the opening 17.

As described above, the plasma generating apparatus 1 according to the present invention has an alternating current between the first electrode 13 and the second electrode 14 whose positions are different from each other along the flow direction (Y direction) of the gas flow path P. Apply voltage. Thereby, a discharge is generated in the flow path P, and the gas is turned into plasma. The discharge at this time is a dielectric barrier discharge, and the electrodes 13 and 14 are isolated from the plasma generated in the flow path P by the dielectric. Therefore, even if the opening 17 is brought close to the conductive processing target, the discharge current does not flow through the processing target. Therefore, it is possible to prevent the processing target from being damaged by the electric current. Further, the electrode material is not mixed into the plasma, and the contamination of the processing target by the constituent material of the electrode is prevented.

Each of the two sets of electrodes 13 and 14 spaced apart in the Y direction has a pair of electrode plates facing each other across the flow path P and given the same potential. Each of the electrode plates 13a, 13b, 14a, and 14b has opposing surfaces along the X and Y directions, and the pair of electrode plates is arranged so that the opposing surfaces are parallel to each other. In the width direction of the flow path P, which is perpendicular to the Y direction, which is the gas flow direction, and parallel to each of the opposing surfaces, that is, in the X direction, each electrode plate extends outside both ends of the flow path P. For this reason, the electric field formed in the flow path P becomes substantially uniform in the X direction.

(4) With these configurations, plasma that spreads widely in the X direction and the Y direction is generated in the flow path P. By ejecting such plasma from the slit-shaped opening 17 provided at the downstream end of the flow path P, uniform plasma irradiation in the width direction can be realized on the processing target.

The structure of the above-described plasma generator 1 is based on a principle based on the technical idea of the present invention, and can be variously modified when it is realized as an apparatus. For example, each electrode plate of the plasma generator 1 has a rectangular flat plate shape. However, the opposing surfaces of the paired electrode plates need only be flat and parallel to each other, and the electrode shape of the other portions is arbitrary. For example, an electrode having a semicircular cross-sectional shape may be used. The shape of the other portions may be different between the paired electrode plates as long as the shape of the opposing surface is the same.

As described below, the shape of the plasma generator can be variously changed. In each of the modified examples described below, although the structure for forming a flow path sandwiched between a pair of electrode plates is different from the above-described principle diagram, the basic operation principle is the same as the above-described configuration. Therefore, the same components as those described above are denoted by the same reference numerals, description thereof will be omitted, and the features of each modification will be mainly described using a cross-sectional view taken along the XZ plane corresponding to the line AA in FIG. 2A. . About the structure which is not described here, it is possible to use the same thing as the plasma generator 1 mentioned above.

FIGS. 4A to 4E are diagrams showing modified examples of the plasma generator. In the modified example of the plasma generator 2 shown in FIG. 4A, the gas flow path P is formed by an integral and continuous dielectric member. That is, the plasma generator 2 includes a single flow path forming member 21 integrally formed of a dielectric material as a configuration corresponding to the dielectric plates 11 and 12 and the spacers 16a and 16b in the plasma generator 1 described above. Have. The flow path forming member 21 corresponds to a configuration in which a through-hole 22 having a flat cross section whose longitudinal direction is in the X direction is provided so as to penetrate the side surface of the rectangular parallelepiped block 20 made of a dielectric material in the Y direction. The plasma generator 2 having such a configuration also has a function similar to that of the plasma generator 1 described above. In addition, as shown by a dotted line in FIG. 4A, the flow path forming member 21 may be configured to be dividable into several pieces.

4B is a modification of the plasma generator 3 shown in FIG. 4B in which the flow path P in the above-described plasma generator 1 is divided into a plurality in the X direction by spacers 36a, 36b, and 36c. In such a configuration, the plasma generated in each of the divided flow paths is spatially synthesized outside the apparatus, so that the plasma spreading in the X direction is ejected similarly to the above-described plasma generator 1. Is possible.

4C is a modification of the plasma generator 4 shown in FIG. 4C in which the flow path in the above-described plasma generator 3 is configured by a flow path forming member 41 integrally formed like the plasma generator 2. In this case, the ejected plasma can be equivalent to that of the plasma generator 3. Also in this case, the flow path forming member 41 may be configured to be able to be divided into several pieces as shown by the dotted lines.

The plasma generator 5 of the modification shown in FIG. 4D has a through-hole provided in the flow path forming member 51 in which the cross-sectional shape is elliptical, and is different from the above-described plasma generator 4 having a through-hole having a rectangular cross-sectional shape. Is different. As described above, the shape of the through hole constituting the flow path may be appropriately changed.

4E, a plurality of tubes 61 made of a dielectric material are arranged in the X direction between an electrode plate 13a (14a) and an electrode plate 13b (14b). It has a structure. In this configuration, the internal space of the pipe 61 functions as the flow path P. Even with such a configuration, the distribution of the electric field formed by the AC voltage applied to the electrodes is common to the above examples. The plasma generated individually in each tube 61 by the action of the electric field is finally combined, so that the same plasma as in the above example can be ejected.

In addition, when the flow path is divided into a plurality of parts, the flow rate of the gas can be controlled for each divided flow path. Thus, for one type of arrangement of the electrodes, various modifications of the gas flow path can be considered.

Next, a more practical embodiment of the plasma generator based on the above principle will be described with reference to FIGS. 5A to 6C.

FIGS. 5A to 6C are views showing an embodiment of the plasma generator according to the present invention. More specifically, FIG. 5A is a perspective view showing an appearance of the plasma generator 100 of the present embodiment, and FIG. 5B is a partially exploded view thereof. FIG. 6A is a top view of the plasma generator 100. 6B and 6C are a sectional view taken along line AA and a sectional view taken along line BB of FIG. 6A, respectively. Here, for the sake of convenience, the main surface of the plasma generator 100 is assumed to be parallel to the XY plane, but the posture of the plasma generator 100 in an actual use state is arbitrary.

The plasma generator 100 includes a pair of flow path forming members 110 and 120 and a pair of cover members 150 and 160. The flow path forming members 110 and 120 are integrally formed of a dielectric material having plasma resistance such as quartz or ceramic, respectively, and correspond to the dielectric plates 11 and 12 in the above-described principle configuration. That is, the flow path forming members 110 and 120 mainly have a function of forming a gas flow path.

Specifically, as shown in FIGS. 5B and 6B, the flow path forming member 120 is provided adjacent to a thin plate-shaped thin portion 121 along the XY plane and a (−Y) direction side end thereof. Thick portion 122. Of these, the thin portion 121 corresponds to the dielectric plate 12 in the above-described principle configuration. As shown in FIG. 5B, the central portion 121b is a step portion that is further thinned as compared with both end portions 121a in the X direction of the thin portion 121.

At the (−Y) side end of the thick portion 122 of the flow path forming member 120, one or a plurality of cutouts 123 serving as the inlet 103 for receiving gas from the gas supply unit 19 are provided. ing. The thick portion 122 is provided with a groove 124 that functions as the manifold 104 that regulates the flow of the gas introduced from the inlet 103. The groove portion 124 is connected to the step portion 121b of the thin portion 121.

The other flow path forming member 110 has the same structure, specifically, a structure in which the flow path forming member 120 is turned upside down. These are superposed to form a gas flow path. That is, as shown in FIGS. 6A to 6C, the thin portion 111 of the flow path forming member 110 and the thin portion 121 of the flow path forming member 120 are overlapped with each other, so that a gap therebetween is formed in the X direction and the Y direction. An extending channel 106 is formed. The (+ Y) side end of the channel 106 serves as an opening 107 for discharging the gas sent through the channel 106. The shape of the opening 107 is a slit shape whose longitudinal direction is in the X direction, that is, thin in the Z direction and wide in the X direction.

In addition, since the thick portion 112 of the flow path forming member 110 and the thick portion 122 of the flow path forming member 120 are overlapped, they communicate with each other from the (−Y) direction side to the (+ Y) direction side. An inlet 103 and a manifold 104 are formed. The manifold 104 communicates with the flow path 106. In this manner, a gas flow path from the inlet 103 at the (−Y) side end of the flow path forming members 110 and 120 to the opening 107 at the (+ Y) side end is formed. The flow of the gas introduced from the inlet 103 is made uniform in the X direction by passing through the manifold 104, and is sent into the flow path 106.

第 The first electrode 130 and the second electrode 140 are arranged with the gas flow channel 106 interposed therebetween. Specifically, the first electrode 130 is provided on the upstream side in the (+ Y) direction, which is the gas flow direction, and the second electrode 140 is provided on the downstream side.

As described in the principle description, the first electrode 130 is connected to the electrode plate 131 attached to the upper surface of the thin portion 111 of the upper flow path forming member 110 at the same position in the XY direction at the lower flow path. And an electrode plate 132 attached to the lower surface of the thin portion 121 of the path forming member 120. As described above, the electrode plates 131 and 132 are arranged to face each other with the flow path 106 interposed therebetween through the flow path forming members 110 and 120.

Similarly, the second electrode 140 is located on the (+ Y) direction side of the electrode plate 131 and the electrode plate 141 attached to the upper surface of the thin portion 111 of the upper flow path forming member 110 at the same position in the XY direction. And an electrode plate 142 attached to the lower surface of the thin portion 121 of the lower flow path forming member 120. In this manner, the electrode plates 141 and 142 are also arranged to face each other with the flow path 106 interposed therebetween through the flow path forming members 110 and 120.

As shown in FIG. 6C, the (+ X) direction end portions 133 of the electrode plates 131 and 132 extend to the outside of the flow path forming members 110 and 120, and are electrically connected to the side of the flow path forming members 110 and 120. It is connected to the. A part thereof further extends to the (+ X) direction side. On the other hand, as shown in FIG. 6A, the (−X) direction end portions 143 of the electrode plates 141 and 142 extend to the outside of the flow path forming members 110 and 120, and a part thereof further extends in the (−X) direction. Extending to the side. The electrode plates 141 and 142 are also electrically connected to the sides of the flow path forming members 110 and 120.

カ バ ー Cover members 150 and 160 are provided to cover the thin portions 111 and 121 of the flow path forming members 110 and 120 and the first and second electrodes 130 and 140. The extending portions 133 and 143 of the first and second electrodes 130 and 140 extend to the outside of the cover members 150 and 160, and the extending portions 133 and 143 function as connection terminals with a power supply unit that outputs an AC voltage. I do.

The cover members 150 and 160 are provided for the purpose of increasing the mechanical strength of the plasma generator 100 and suppressing the exposure of the electrodes. By reducing the thickness of the dielectric layer at the portion where the electrode is provided, the voltage required for plasma generation can be suppressed. On the other hand, the mechanical strength is reduced by making the dielectric thinner. By reinforcing the thin portions 111 and 121 with the cover members 150 and 160, damage to the device can be prevented. Further, exposure of the electrodes 130 and 140 can be minimized to prevent electric shock and abnormal discharge.

In the plasma generator 100 configured as described above, an appropriate gas, for example, an argon gas is introduced from the inlet 103, and an airflow in the (+ Y) direction is formed in the flow path 106. The air flow is thinned in a flow path 106 that is narrow in the Z direction and wide in the X direction.

In this state, when an AC voltage of an appropriate magnitude is applied between the first and second electrodes 130 and 140, a dielectric barrier discharge occurs in the flow path 106 according to the above-described principle. As a result, plasma is generated in the flow path, and the gasified into plasma is discharged from the opening 107 to the outside. The flow path 106 has a flat cross-sectional shape whose longitudinal direction is the X direction, and the opening 107 has the same slit-shaped opening shape as the cross-sectional shape. The first and second electrodes 130 and 140 are provided beyond the width of the flow path 106 in the X direction. For this reason, the electric field formed in the flow path 106 is substantially uniform in the X direction.

Therefore, in the flow path 106, plasma having a substantially uniform density is generated in the X direction, and the plasma gas discharged from the opening 107 spreads in the X direction. By irradiating such a plasma to a processing target such as a substrate or a printing medium, the surface of the processing target can be efficiently processed.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention. For example, in the above-described embodiment, a pair of electrode plates constituting the first electrode pair is electrically connected in parallel to the power supply unit, so that both are at the same potential. Instead, a power supply unit may be individually connected to a pair of electrode plates, and the outputs of the power supply units may be synchronized so that both electrode plates have the same potential. The same applies to the second electrode pair.

In addition, the cross-sectional shape of the flow channel in the above embodiment is constant with respect to the gas flow direction. However, for example, in order to control the gas flow rate and the discharge range, the cross-sectional shape of the flow path may be gradually changed in the gas flow direction.

Also, for example, each of the first electrode pair and the second electrode pair may be formed in an annular shape with the Y axis as the axial direction and surrounding the flow path. Further, for example, in the above embodiment, the power supply unit is connected between the first electrode and the second electrode, but any one of the electrodes may be grounded.

As described above, in the plasma generator of the present invention, for example, the opposing surfaces between the first electrode and the second electrode may be parallel to each other as described in the specific embodiments. According to such a configuration, a uniform electric field can be formed in a flow path passing between the first electrode and the second electrode in a direction parallel to the opposing surface, and the plasma density spreading in the same direction can be made uniform. It can be.

Further, for example, the respective structures of the first electrode and the second electrode may be parallel flat plates. According to such a configuration, a device for irradiating a wide range of plasma can be realized with a simple electrode structure.

Also, for example, the first electrode and the second electrode may extend to the outside of the flow path in a direction perpendicular to the flow direction and parallel to the facing surface. According to such a configuration, it is possible to prevent the disturbance of the electric field near the end of the electrode from affecting the inside of the flow path, and to generate more uniform plasma in the flow path.

Also, for example, the cross section of the flow path in a cross section perpendicular to the flow direction may have a flat cross section whose longitudinal direction is parallel to the facing surface. Further, the flow path forming section may have a configuration having a plurality of flow paths arranged along a direction perpendicular to the flow direction and parallel to the facing surface.

Furthermore, for example, the flow path may be a gap space sandwiched between a pair of wall surfaces that are opposed to each other in parallel and close to each other. The wall surface may be formed of a pair of parallel plate-like dielectrics.

Also, for example, a configuration may be provided that includes a gas supply unit that supplies gas to the upstream end in the flow direction of the flow path. According to such a configuration, it is possible to actively control the type and amount of gas in the flow path.

The present invention can be suitably applied to the technical field of treating the surface of various processing objects with plasma. In particular, since wide plasma can be emitted into the air atmosphere with a simple configuration, it is particularly suitable for surface treatment of, for example, a substrate or a print medium.

Although the invention has been described with reference to specific embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover any such modifications or embodiments without departing from the true scope of the invention.

1,100 Plasma generator 11,12 Dielectric plate (flow path forming part)
13 (13a, 13b), 130 (131, 132) First electrode 14 (14a, 14b), 140 (141, 142) Second electrode 15 Power supply section 16a, 16b Spacer (flow path forming section)
17, 107 opening 19 gas supply section 106, P flow path 110, 120 flow path forming member (flow path forming section)

Claims (9)

1. Forming a flow path for flowing the gas along a predetermined flow direction, at a downstream end of the flow path in the flow direction, a flow path forming unit having an opening for discharging the gas,
   A first electrode having a pair of opposing surfaces parallel to each other and arranged opposite to each other across the flow path;
   A second electrode having a pair of parallel opposing surfaces that are spaced apart from the first electrode in the flow direction and that are arranged to oppose each other across the flow path;
   A power supply unit for applying an AC voltage between the first electrode and the second electrode,
   Each of the facing surfaces of the first electrode is a plane parallel to the flow direction and facing the other first electrode, and a gap between the facing surface of the first electrode and the flow path is made of a dielectric material. Isolated,
   Each of the opposed surfaces of the second electrode is a plane parallel to the flow direction and opposed to the other second electrode, and a gap between the opposed surface of the second electrode and the flow path is made of a dielectric. An isolated plasma generator.
2. The plasma generator according to claim 1, wherein the opposed surface of the first electrode and the opposed surface of the second electrode are parallel to each other.
3. 3. The plasma generator according to claim 2, wherein each of the first electrode and the second electrode has a parallel plate structure.
4. 4. The plasma generator according to claim 1, wherein the first electrode and the second electrode extend outside the flow path in a direction perpendicular to the flow direction and parallel to the facing surface. 5.
5. 4. The plasma generator according to claim 1, wherein a cross section of the flow path in a cross section perpendicular to the flow direction has a flat cross section whose longitudinal direction is parallel to the facing surface. 5.
6. The plasma generating apparatus according to claim 5, wherein the flow path is a gap space sandwiched between a pair of wall surfaces that are opposed to each other in parallel and close to each other.
7. The plasma generator according to claim 6, wherein in the flow path forming portion, a pair of parallel plate-shaped dielectrics constitute the wall surface.
8. The plasma generator according to any one of claims 1 to 4, wherein the flow path forming section has a plurality of the flow paths arranged in a direction perpendicular to the flow direction and parallel to the facing surface.
9. The plasma generator according to any one of claims 1 to 8, further comprising a gas supply unit that supplies the gas to an upstream end of the flow path in the flow direction.

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